Individual psychological interventions and therapies for posttraumatic stress disorder and posttraumatic stress symptoms in young children: a systematic review

ABSTRACT

Context: Treatments for posttraumatic stress disorder (PTSD) in young children (ages 0–6) should be adapted to their developmental characteristics: to their cognitive, social, and emotional abilities, to their specific trauma reactions and adjustments, and finally, to their degree of dependency on adults. Due to the lack of official recommendations for the treatment of PTSD in young children and considering the high prevalence of PTSD among this population, there is a growing need for targeted psychological interventions and psychotherapies for the youngest children with PTSD or posttraumatic symptoms.

Objective: To provide an update on effective psychological interventions available for the treatment of PTSD and posttraumatic symptoms in young children (under the age of 6).

Design: Systematic review of automated searches conducted using the search engines Google Scholar, Science Direct, PsycInfo, and PubMed.

Results: This review identified 17 articles reporting on the efficacy of an individual therapy for treating PTSD or posttraumatic stress symptoms in young children. The therapies identified are TF-CBT, CPP, PCIT, DET, early pathway, EMI and EMDR.

Conclusion: No treatment can currently be identified as a level-one evidence-based treatment (Well-Established Treatment) in children younger than 6 years old with PTSD or posttraumatic symptoms. Further research is essential to validate existing findings on the effectiveness of trauma-focused therapies in young children in order to establish internationally recognized recommendations.

HIGHLIGHTS

• Due to the lack of official recommendations, there is a growing need for targeted psychological interventions and psychotherapies for the youngest children with posttraumatic symptoms. This systematic review appears to be the first comprehensive review focused on this topic.

• This work identified 17 articles reporting on the efficacy of an individual therapy for treating posttraumatic stress symptoms in young children. The therapies identified are the trauma-focused cognitive behavioural therapy, the eye movement desensitization and reprocessing, the child–parent psychotherapy, the parent–child interaction therapy, the dyadic exposure therapy, the early pathway with trauma components, and the eye movement integration therapy.

• This review discusses how each treatment proposes to respond to the needs of this specific population (cognitive, social, and emotional abilities, specific trauma reactions and adjustments, specific assessment, dependency on adults) but no treatment can currently be identified as a level-one evidence-based treatment in children younger than 6 years old with posttraumatic symptoms.

1. Introduction

1.1. Context

It is common for young children and preschoolers (ages 0–6) to be exposed to traumatic events (Woolgar et al., 2022) and adversity. Prevalence research suggests that a quarter to a half of children may have experienced at least one traumatic event in their lifetime during the preschool age (Briggs-Gowan et al., 2010; Egger & Angold, 2004; Finkelhor et al., 2015). Children under the age of 6 are notably a high-risk group for exposure to domestic or interpersonal violence and maltreatment (Fantuzzo & Fusco, 2007; Finkelhor et al., 2013; US. Department of Health & Human Services, 2018).

Following exposure to a traumatic event, children under the age of 6 are as vulnerable to develop a posttraumatic stress disorder (PTSD) as their elders. Recently, a meta-analysis estimated at 21.5% (95% CI = 13.8%−30.4%) the PTSD prevalence in preschool trauma-exposed children (Woolgar et al., 2022). This would mean that almost one-fourth of preschool-aged children meet diagnostic criteria for PTSD after an at-risk exposure.

PTSD involves alterations in memory, sensory, emotional, and behavioural mechanisms. These alterations are expressed by intrusive symptoms, avoidance symptoms, changes in mood and cognitions, changes in arousal, and a functional impairment (American Psychiatric Association, 2022).

Untreated traumatic reactions in young children would lead to chronic consequences (Scheeringa et al., 2005), seem to be strongly associated with psychiatric comorbidities (Scheeringa & Zeanah, 2008) and may be under-recognized by parents (Meiser-Stedman et al., 2017). Moreover, childhood adversities seem to be significantly associated with adult psychiatric disorders (Green et al., 2010).

Therefore, the consequences of a traumatic experience in very young children should be treated early and effectively.

1.2. Study justification

As supported by several large institutions in different countries, psychological interventions should be the first instance treatment for people with PTSD.

For adults with a diagnosis of PTSD, trauma-focused cognitive behavioural therapy (TF-CBT) or eye movement desensitization and reprocessing (EMDR) seem to be the most highly recommended therapies world-wide (APA, 2017; HAS, 2007; NICE, 2018; WHO, 2013). However, the American Psychiatric Association suggests that the evidence for interventions on children with PTSD remains insufficient to make recommendations (APA, 2017).

The United Kingdom and the National Institute for Health and Care Excellence (NICE) recommend TF-CBT or EMDR for children and young people aged 7–17 years with a diagnosis of PTSD or clinically important symptoms of PTSD (NICE, 2018). NICE also advises against the use of drug treatments for the prevention or treatment of PTSD in children.

Despite studies reporting the effectiveness of individual therapies for treating children under 6 with posttraumatic symptoms, no official recommendations or guidelines have been made for treatment of this specific population.

Given the evidence confirming that children do not recover in the absence of treatment (Meiser-Stedman et al., 2017; Scheeringa et al., 2011) and considering the absence of treatment guidelines for PTSD and traumatic reactions in children under 6, there is a strong need for targeted, effective interventions for young children with PTSD and trauma symptoms.

Since the literature suggests notable differences in trauma reactions among preschoolers (DC:0–5™: ZERO TO THREE, 2016; American Psychiatric Association, 2022; Mckinnon et al., 2019; Scheeringa, 2008), treatments for PTSD in young children should be adapted to their developmental characteristics. Young children need interventions suited to their cognitive, social, and emotional abilities, to their specific trauma reactions and adjustments, and finally, to their level of dependency on adults. Therefore, it seems important to know how to provide psychological interventions adapted to the developmental characteristics of young children with PTSD.

We found three reviews that specifically address the treatment of PTSD in young children. The first review focuses exclusively on the application of TF-CBT to Preschool-Aged Children (McGuire et al., 2021), the second investigates interventions in the context of disasters and terrorism alone (Wolmer et al., 2017), and the last one, which is not a systematic review, only focuses on three evidence-based treatments (Vanderzee et al., 2019).

We, therefore, conducted a new systematic review that includes all types of individual psychological interventions and individual therapies for young children with PTSD or trauma symptoms following all types of traumatic events.

This work aims to help paediatric clinicians identify the individual psychological interventions available to treat trauma symptoms and PTSD among very young children and to guide them in the choice of the method to be applied in public health services or in private practice. Also, this inventory may encourage researchers to increase the number of trials focusing on the treatment of PTSD in young children so that official guidelines can be written.

2. Method

2.1. Design and strategy

This study reports on a systematic review conducted using the PRISMA criteria (Liberati et al., 2009). We searched for published quantitative studies regarding the efficacy of individual psychological interventions and individual psychotherapies for treating PTSD symptoms in young children. PubMed, PsycInfo, Science Direct, and Google Scholar search engines were selected as information sources.

Specific key words were used to identify the population, the disorder, and the interventions. All combinations of the name given to the population, the disorder, and the interventions were searched for (Population X Disorder X Intervention). Keywords used to search for the disorder were PTSD, Post-Traumatic Stress Disorder, Trauma and Stress. Keywords used to search for the population were Young Child, Very Young Child, Preschooler, Toddler, Infant, Babies, Preverbal Children, and Early childhood. Keywords used to search for the interventions were Treatment, Psychological Intervention, Psychotherapy, Therapy, CBT, Cognitive Behavioural Therapy, TF-CBT, Trauma-Focused Cognitive Behavioural Therapy, EMDR, Eye Movement Desensitization and Reprocessing, CPP, Child Parent Psychotherapy, PPT, Preschool PTSD Treatment, Play Therapy, PCIT, Parent–Child Interaction Therapy, Exposure Therapy, Behavioural Therapy, and Cognitive Therapy.

The keywords were determined using the MEDLINE-PubMed system and the Medical Subject Headings (MeSH) but were also determined by the current words used in the psychological and developmental literature. The choice was made to search for different types of existing therapies in addition to searching with more comprehensive words like ‘treatment’.

The automatic search was carried out from October 2021 to June 2022. The search was updated between September 2023 and November 2023, with the same keyword combinations.

The studies were selected and sorted in predefined stages. The first step consisted in selecting the studies based on title suitability, a second step on abstract relevance, and a final step on the full reading of relevant articles. Seventeen studies were included after applying the systematic search.

Included studies were analysed qualitatively in a double read according to the STARD model (Gedda, 2015). Extracted data included the authors, the title, the year of publication, the age of the population treated, the characteristics of the sample, the method of assessment, the results of the study, the limitations, and the description of the evaluated psychological intervention. A table summarizing this data is presented below (Table 2).

Table 2.

Summary of results.

Authors	Type of study	Therapy	Participants	Measures	Results	Limits
Hitchcock et al., 2022	Randomized Controlled Trial	CBT7 – 3M	N = 37 Ages  =  3–8 years old M = 6.5 SD = 1.9 Type of traumatic exposure: Different types (e.g. accidental injury, acute medical emergency, victims, or witnesses of a physical or sexual assault or other interpersonal event involving threat of injury/life)	- DIPA (Scheeringa & Haslett, 2010) - YCPC (Scheeringa, 2010) - PEDS (Saylor et al., 1999) - Preschool feelings checklist (Luby et al., 2004)	On DSM-5 PTSD-Young Children diagnosis: at post-treatment 84.6% (n = 11) of children in the CBT-3M group lost their PTSD diagnosis relative to 6.7% (n = 1) of children in the treatment as usual group. Significant large effect size (Quade’s test) in favour of CBT-3M at post-treatment on: - Preschool Feelings Checklist, t(7.45) = 4.07, d = 1.34, 95% CI [0.62, 2.05], p = .004. At three-month follow-up all 8 of the assessed participants did not meet criteria for PTSD-YC in the CBT 3 M Group.	- Age of the sample (children between 3 and 8 years old: different developmental specificities) - Feasibility of the follow-up assessment (attrition)
Cohen & Mannarino, 1996	Randomized Controlled Trial	CBT – SAP Compare to NST	N = 86 Ages = 3–6 years old M = 4,68 SD = NR Type of traumatic exposure: Sexual Abuse	- PRESS (Martini et al., 1990) - CBCL (Achenbach & Edelbrock, 1983) - CSBI (Friedrich & al., 1992) - WBR (Cohen & Mannarino, 1993)	Significant pre to post improvements for CBT treatment on the CBCL int (t = 5.14, P < .05), CBCL ext (t = 4.28, P < .05), CSBI (t = 4.11, P < .05) & WBR total (t = 5.08, P < .05). Significant differences between the groups CBT & NST: CBT group was less symptomatic on CBCL int (t = −3.16, P < .01), CBCL ext (t = −1.58, p < .002), CSBI (t = −2.38, P < .05) & WBR total (t = −2.28, P < .05). No significant changes on the PRESS evaluation (pre to post & between groups).	- Blinded method (outcome assessors were not blinded to the intervention provided) - Assessment method (not based on the most recent diagnostic algorithms)
Cohen & Mannarino, 1997	Follow-up of a Randomized Controlled Trial (Cohen & Mannarino, 1996)	CBT – SAP Compare to NST	N = 43 Ages = 4 years and 2 months – 7 years and 11 months M = 5 years and 9 months SD = NR Type of traumatic exposure: Sexual Abuse	- CBCL - CSBI - WBR	Significant group by time interactions on CBCL Behaviour Profile Total (F = 3.78, p < 0.01) CBCL Int measures (F = 4.80, p < 0.01); CBCL Ext measures (F = 2.63, p < 0.01); WBR Total (F = 4.29, p < 0.01) from the beginning of the study to the end of the 12-month follow-up period. CBT-SAP group exhibiting significantly more improvement over time than NST group.	NR
Hébert & Daignault, 2015	Single arm interventional study	TF CBT	N = 25 Ages = 3–6 years old M = 5,26 SD = NR Type of traumatic exposure: Sexual Abuse	- CBCL (Achenbach & Rescorla, 2000, 2001) - CPTS-RI-PQ (Nader, 1994) -CDC (Putnam et al., 1993)	Significant pre to post improvements on CBCL: ->reduction of internalised (t = 4.46, P = 0.000, d = 0.89) and externalised (t = 4.17, P = 0.000, d = 0.83) behaviour problems. Significant pre to post improvements on CDC: reduction of dissociation symptoms (t = 5.34, P = 0.000, d = 1.07). Significant pre to post improvements on CPTS-RI-PQ: reduction of global PTSD score (t = 3.82, P = 0.002, d = 0.94). Treatment effects were maintained at the follow-up conducted 6 months following the end of treatment.	- No control groups - Small sample size (with attrition at the follow-up assessment) - Assessment method (not based on the most recent diagnostic algorithms)
Scheeringa et al., 2011	Randomized Controlled Trial	TF-CBT (PPT) Compare to A Waiting List (WL)	Phase 1: N = 11 Phase 2: N = 64 Ages = 36–83 months. M = 5.3 SD = 1.1 Type of traumatic exposure: Different types (e.g. acute injury, witnessed domestic violence, and victim of a natural disaster)	- PAPA (Egger et al., 2006) - DSM-IV algorithm (APA, 1994) - The PTSD-AA (Scheeringa et al., 2003) - The Adverse Events Checklist (AEC: designed for this study)	Pre-post effect size (Cohen’s d measure) for PTSD in treatment group: d = 1.48 (WL effect size d = 0.16). Time by Group interaction: F = 12.97, df = 28, p < 0.005 Pre-post effect size for PTSD after combining ‘Immediate Treatment group’ and children treated from the Wait List (d = 1.01), at 6 months (d = 1.88)	- Blinded method (not fully described) - Attrition (large amount of drop out (56.4%, n = 22, dropped in IT; 52.2%, n = 12; dropped in WL))
Caouette et al., 2021	Single arm interventional study	TF CBT - AVI	N = 33 Ages = 4–6 years old M = 4.79 SD = 0.65 Type of traumatic exposure: Sexual Abuse	- History of Victimization Form (Wolfe et al., 1987) - CBCL - Child Dissociative Checklist (CDC; Bernstein & Putnam, 1986)	Significant reduction of internalizing behaviour problems (t(30) = 2.90, p < .01, d = 0.52), significant decreasing on mean scores of dissociative symptoms (t(32) = 2.60, p < .05, d = 0.45). No significant reduction for child externalizing problems (t(30) = 1.36, p = 0.19, d = 0.24).	- No control groups - Many confounding variables - Assessment method (not based on the most recent diagnostic algorithms) - No follow-up assessment (a third evaluation period, several months after the intervention)
Salloum, Robst, et al., 2014	Single arm interventional study	SC-TF-CBT	N = 9 Ages = 3–6 years old M = 4.7 years SD = 0.87 Type of traumatic exposure: Different types (e.g. Sexual or Physical Abuse, domestic violence, homeinvasion robbery)	- DIPA - TSCYC-PTS (Briere, 2005) - The Clinical Global Impression- Severity & improvement (CGI; NIMH, 1985)	Results for Step One responders (N = 5): Cohen’s d Baseline to post DIPA – PTS (d = 1.37) TSCYC – PTS (d = 3.13) Cohen’s d baseline to follow-up: DIPA – PTS (d = 2.00) TSCYC – PTS (3.03) 83.3% (5/6) children who completed the treatment no longer met PTSD criteria after the Step One and no children responded to PTSD diagnosis at the end of treatment (Step Two). Only one child remained above the clinical cut off score on the TSCYC after the Step One treatment. Treatment gains were maintained at the follow-up, except for one case (with new traumatic experiences).	- No control groups - Small sample size
Salloum et al., 2016	Randomized Controlled Trial	SC-TF-CBT And TF-CBT	N = 53 Ages = 3–7 years old M = 5.04 years SD = 1.49 Type of traumatic exposure: Different types (e.g. Sexual Abuse, domestic violence, grief)	- TSCYC - CGI-Severity - CGI – Improvement - CBCL - DIPA	SC-TF-CBT was not inferior to standard TF-CBT on all variables except for externalizing T scores (p = .09). SC-TF-CBT group Effect size Cohen’s d Baseline to post TSCYC – PTS (d = 1.57)/3 months follow-up TSCYC – PTS (d = 1.59). TF-CBT group Effect size Cohen’s d Baseline to post TSCYC – PTS (d = 1.10)/3 months follow-up TSCYC – PTS (d = 1.39). No statistical differences in remission (PTSD diagnostic status) between SC-TF-CBT and TF-CBT at post-treatment (42.9% vs. 27.8%, p = .439, χ2(1) = 0.60) and follow-up (45.7% vs. 33.3%, p = .567, χ2(1) = 0.33).	- Small sample size - Need for larger, diverse samples for treatment trials. - Longer follow-up to assess treatment maintenance. - Limited cost data; broader research needed.
Lieberman et al., 2005	Randomized study (CPP/case management plus community referral for individual treatment)	CPP	N = 75 Ages = 3–5 years old M = 4.06 years SD = 0.82 Type of traumatic exposure: witnessed or overheard marital violence.	- Children’s Exposure to Community Violence: Parent Report Version (Richters & Martinez, 1993) - CBCL - Traumatic Stress Disorder (TSD): Semi structured Interview for Diagnostic Classification DC: 0–3 for Clinicians (ZERO TO THREE: National Center for Clinical Infant Programs, 1994) - CAPS (Blake et al., 1990).	Significant group X time interaction for the total number of TSD symptoms (F 1,59 = 10.98, p < .001, d = 0.63). Follow-up analyses: only the CPP group had a significant intake-posttest reduction in the number of TSD symptoms (t(32) = 5.46, p < .001). Significant group X time interaction for the CBCL Total scores (F1,61 = 5.77, p < .05, d = 0.24) Follow-up analyses: only the CPP group evidenced significant intake-posttest reductions (t(34) = 2.86, p < .01). At posttest: significant group difference on the PTSD diagnostic criteria (χ2 (n = 61) = 8.43, p < .01, $\mathrm{\Phi }$ = 0.37), with 6% (n = 2) of children in the CPP group and 36% (n = 10) of children in the comparison group meeting criteria for PTSD.	- Blinded method (not fully described) - Attrition (14,3%) - Long participation efforts for families (four sessions of assessment and 50 weeks of treatments) - Assessment method (not based on the most recent diagnostic algorithms) - The follow up study does not include a PTSD assessment
Ghosh Ippen et al., 2011	Reanalysis of data	CPP	N = 75 Ages = 3–6 years old M = 4.06 SD = 0.82 Type of traumatic exposure: Exposed to marital violence and different types of cumulative risk exposure (e.g. Sexual or physical Abuse, separation from the caregiver)	- CBCL - Screening Survey of Children’s Exposure to Community Violence: Parent Report Version - Semi structured Interview for Diagnostic Classification DC: 0–3 for Clinicians (Scheeringa et al., 1995)	Child improvement (across risk status): Children in CPP group were showing significant improvement on CBCL (> 4 risk exposures). They had a greater improvement on PTSD symptoms [t(73) = −3.24, p < .01, d = .75] and depression symptoms [t(73) = −2.21; p < .05]	NR
Hagan et al., 2017	Single arm interventional study	CPP	N = 199 Ages = 2–6 years old M = 49.14 months SD  = 11.9 Type of traumatic exposure: Interpersonal trauma exposure (e.g. community violence, domestic violence, caregiver death)	- TSCYC - TESI-PRR	Significant improvement on reexperiencing (M = −2.37, SE = 0.36, p < .001); hyperarousal (M = −3.03, SE = 0.40, p < .001) and avoidance symptoms (M = −1.43, SE = 0.31, p < .001).	- No comparison groups - Few assessments scale (and absence of a scale allowing the diagnosis of PTSD) -Including children under 3 years old, but assessment method designed for ages 3–12 (TSCYC) and not based on recent diagnostic algorithms -Treatment outcomes do not take age into account as a moderator despite the inclusion of very young children (< 3 years) - No follow-up assessment (a third evaluation period, several months after the intervention)
Weiner et al., 2009	Single arm interventional study	CPP	N = 65 Ages < 6 years old M = 3.7 SD = 1.6 Type of traumatic exposure: Different types (e.g. sexual abuse, physical abuse, emotional abuse, neglect)	- Child and Adolescent Needs and Strengths (CANS; Lyons, 2004)	Outcome measures at baseline and follow-up are presented by ethnicity: African American, Biracial, and Hispanic children experienced significant improvement in Traumatic Stress Symptoms and CANS domain (child strengths, life domain functioning; behavioural/emotional needs and risk behaviours). For CPP, the only significant predictors of change in traumatic stress symptoms were baseline traumatic stress symptoms (β =  .475, p = .000) and number of sessions (β = −.108,2 p = .027).	- No comparison groups - Results presented only by ethnicity - Sample diversity (foster families) - Assessment method (a single measure, not specific to young children) - Treatment outcomes do not take age into account as a moderator despite the inclusion of very young children (< 3 years)
Rachamim et al., 2021	Randomized Controlled Trial	DET & DCCT	N = 12 Ages = 2,5–5,5 years old M = 49.25 months SD = 13.84 Type of traumatic exposure: single-incident or medical trauma	- DIPA - YCPC	Significant pre to post improvements on the DIPA for DET treatment: (t = 4.53, P = .006, d = 1.85) & on the YCPC for DET treatment: (t = 3.17, P = .025, d = 1.29). Significant pre to post improvements on DIPA for DCCT treatment: (t = 3.15, P = .025, d = 1.29) No significant pre to post improvements for the DCCT treatment on the YCPC. At the 3 month follow up: Children in DET group showed significant improvements in PTSD symptoms on the DIPA and the YCPC severity scores (Md = 57.50, SD = 23.91, t = 5.89, P = .002; Md = 37.17, SD = 24.09, t = 3.78, P = .013, respectively). In the DCCT group, no significant reductions in children’s PTSD symptoms (measured by DIPA and YCPC) were found.	- Small sample size - Comparative focus (the trial wasn't designed to directly compare the efficacy of the two interventions) -Treatment outcomes do not take age into account as a moderator despite the inclusion of very young children (< 3 years)
Pearl et al., 2012	Single arm interventional study	PCIT	N = 53 Ages = Unprecise M = 5,45 years SD = 2,46 Type of traumatic exposure: Different types (e.g. Sexual or Physical Abuse, neglect, seeing a dead body)	- Childhood Trust Events Survey-Caregiver Version (CTES; Trauma Treatment Training Center, 2006) - The UCLA PTSD Index (Pynoos et al., 1998) - Eyberg Child Behaviour Inventory (ECBI; Eyberg, 1978) - CBCL - TSCYC	On ECBI: From pretreatment to posttreatment, large effect sizes were obtained on both the Intensity scale (d = 1.19) and on the Problem scale (d = 1.60). On CBCL: Every subscale showed significant improvement (p.< 05) from pretreatment to posttreatment except for Social Problems-school age version (n = 18, p = .096). On TSCYC: Significant improvement was seen on the Sexual Concerns subscale (p = .029) from pretreatment to posttreatment, and all other subscales showed significant improvement at p. < 01. Medium effect sizes were seen on Posttraumatic Stress-Total Scale (d = .74)	- No comparison groups - Attrition/dropouts - Assessment method (not based on the most recent diagnostic algorithms, assessing the PTSD symptomatology but not the diagnosis)
Love & Fox, 2019	Randomized Controlled Trial	EP (Early pathways) with new trauma informed components (from CBT treatments)	N = 64 Ages = 1–5 years old M = 39.11 months SD = 13.32 Type of traumatic exposure: NR	- TESI-PRR (Ghosh-Ippen et al., 2002) - ECBS (Holtz & Fox, 2012) - PEDS - PCRS (Fox & Nicholson, 2003)	Significant differences between the treatment group and the WL group: on the ECBS-CBS with a large effect size [F (1, 61) = 25.55, p < .001, Cohen’s d = .97]/on the PEDS-AW with a large effect size [F (1, 60) = 22.97, p < .001, Cohen’s d = 1.05]/on the PEDS-F with a medium effect size [F (1, 60) = 8.04, p < .01, Cohen’s d = .59] / on the PCRS with a medium effect size [F (1, 56) = 7.70, p < .01, Cohen’s d = .52]. Follow up analysis (after that children in the WL group received the treatment): Significant changes: on the ECBS-CBS from pretest to follow up with a medium effect size [F(2, 40) = 10.78, p < .001, Cohen’s d = .75]/on PEDS-AW with large effect sizes [F(2, 40) = 11.99, p < .001, Cohen’s d = 1.04] and PEDS-F [F (2, 40) = 8.57, p < .01,Cohen’s d = .80]/on the PCRS with large effect sizes [F(2, 30) = 10.53, p < .01,Cohen’sd = .97]. No significant differences between group on any measures at follow-up.	- Sample diversity (families living in poverty) - Attrition challenges - Assessment method: not based on the most recent diagnostic algorithms/Trial including children under 2 years old, but assessment method designed for ages 2–10 (PEDS) -Treatment outcomes do not take age into account as a moderator despite the inclusion of very young children (< 3 years)
Olivier et al., 2021	Multiple baseline experimental design	EMDR	N = 9 Ages = 4–8 years old M = 61 months, SD  = 13 Type of traumatic exposure: Diferent types (e.g. grief, domestic violence, medical trauma)	DIPA TSCYC SDQ + Daily Measures of the Two Main PTSD Symptoms	Improvements on the DIPA: 85,7% of remission (pre-post)/87,5% of remission (3 months follow-up). All participants showed a reliable reduction on the TSCYC PTSD: Reliable changes Pre-post 100% (N = 8)/Reliable changes 3 months follow-up 100% (N = 6). For the SDQ three participants showed a reliable reduction: Reliable changes Pre-post 37,5% (N = 8), / Reliable changes 3 months follow-up 50% (N = 6). Result on diary data indicate a decline in the two main PTSD symptoms during treatment.	- Small sample size - No control groups - Age of the sample (children between 4 and 8 years old: different developmental specificities) - Incomplete measurements
Van der Spuy & van Breda, 2019	Single arm interventional study	EMI	N = 12 Ages = 5–7 years old M = NR SD = NR Type of traumatic exposure: Different types (e.g. sexual abuse, domestic violence, medical trauma)	- TSCYC (Briere, 2005)	- Significant improvements in all TSCYC sub-scales, except for sexual concerns. - Eleven out of 12 children experienced a decrease in total PTS symptoms. - Decrease in intrusion, avoidance, and arousal clusters, with improvements in nine or 10 children - Effect sizes are notably large, all above 0.50, except for Dissociation, which is medium-to-large.	- Small sample size - No control groups - Exploratory Design and preliminary findings - Assessment method (a single measurement, not based on the most recent diagnostic algorithms, and assessing the PTSD symptomatology but not the diagnosis) - Sample diversity (from private practice) - No follow-up assessment (a third evaluation period, several months after the intervention)

Abbreviations: N.R., not reported; SD, standard deviation; M, mean age.

2.2. Inclusion criteria

This review includes quantitative studies written and published in English regarding the efficacy of an individual psychological intervention for treating PTSD or symptoms of PTSD in young children. The population covered was children from 0 to 6 years old, but the review also includes research with older children (up to 8 years old if the mean age was less than 6.5 years). Therefore, the included studies have samples of children aged 0–8 years.

2.3. Exclusion criteria

This review excludes articles that are not written in English, articles about case studies or about group interventions, studies about interventions focusing on parenting skills only, articles that report on qualitative studies or on quantitative studies using tools that do not assess posttraumatic symptoms, studies about preventive interventions or early interventions (e.g. less than a month between exposure to a traumatic event and treatment, since early interventions treat acute stress, while PTSD can only be identified after the persistence of trauma symptoms for more than a month). Finally, this review excludes studies describing treatments of questionable efficacy (Southam-Gerow & Prinstein, 2014) or with insignificant results.

Studies that did not include children under 6 years of age were excluded. And finally, studies that include children over 8 years old were not included, even if the analysis used age as a moderator. This choice was made because in studies that include children over 8 years old the therapy protocols have not specifically been designed for young children (taking into account their developmental characteristics). However, as mentioned in the introduction, it seems essential that the youngest children receive treatments adapted to their age and level of cognitive and verbal development.

2.4. Study selection and sorting (Table 1)

Table 1.

Identification of studies via databases and registers.

3. Results

3.1. Identified studies

The final sample comprised 17 articles that examine an individual psychotherapy or psychological intervention in young children (range: 1–8 years old) and matched our inclusion criteria. Detailed data on each of these 17 studies can be found in Table 2, and an analysis of the risks of bias (an analysis of the risks of bias carried out with the Mixed Methods Appraisal Tool of 2018 (MMAT 2018; Hong et al., 2019) for each study is available in the appendices.) for each study is available in the appendices.

Despite a large number of articles dealing with Play Therapy reviewed during the title selection stage, none of these studies were included in the review because they all involved case studies or were qualitative analyses.

It is important to note that one of the studies reviewed (Rachamim et al., 2021) described the effects of two therapies, DET (dyadic exposure therapy) and DCCT (dyadic client-centred therapy), but only one of the two protocols showed significant results in reducing posttraumatic symptoms in children. It appears that children in the DCCT group showed a significant improvement in PTSD diagnosis at posttreatment (assessed by the DIPA), but it was not maintained at follow-up. Also, children in the DCCT group did not show significant improvement in posttraumatic symptomatology (YCPC). This therapy could be described as a treatment of questionable efficacy (Southam-Gerow & Prinstein, 2014) to treat PTSD in young children. The reasons that could explain these results are not discussed by the authors, but we note that the DCCT is focused on establishing a trusting and empowering child-caregiver and therapeutic attachment. It is a non-directive supportive therapy which does not offer modules focusing on the reduction of post-traumatic symptoms presented by the child, and the manual does not contain detailed trauma-focused methods for each session, or direct suggestions to readapt cognitions and behaviours. In contrast to this, the organizations offering recommendations for PTSD in childhood such as the National Child Traumatic Stress Network (NCTSN, 2018), recommends that the trauma-focused interventions include core components such as: psychoeducation about posttraumatic stress reactions (to strengthen coping skills); teaching emotional regulation skills (to strengthen coping skills); constructing a trauma narrative (to reduce posttraumatic stress reactions); teaching safety skills; and others.

The various protocols discussed next, except for PCIT, are all described as trauma interventions.

3.1.1. Cognitive behavioural therapies – CBTs

The systematized search identified eight studies that assess the effectiveness of CBTs in young children with PTSD or posttraumatic symptoms.

CBTs are the most widely studied treatments for reducing PTSD diagnosis and symptoms in children (Cohen et al., 2017; de Roos et al., 2011) and are recognized short-term therapeutic interventions. For the specific treatment of trauma symptoms, there are dedicated protocols: trauma-focused cognitive behavioural therapy (TF-CBT).

To date, four randomized controlled trials (Cohen & Mannarino, 1996; Hitchcock et al., 2022; Salloum et al., 2016; Scheeringa et al., 2011), three single-arm interventional studies (Caouette et al., 2021; Hébert & Daignault, 2015; Salloum, Robst, et al., 2014), and one follow-up of a randomized controlled study (Cohen & Mannarino, 1997) have examined the efficacy of CBTs in individual sessions with young children (range: 3–8 years old) suffering from PTSD or posttraumatic symptoms. Only two studies have samples of more than 60 participants (Cohen & Mannarino, 1996; Scheeringa et al., 2011), and the smallest sample (a pilot) was nine participants (Salloum, Robst, et al., 2014).

Four of the eight studies (Caouette et al., 2021; Cohen & Mannarino, 1996, 1997; Hébert & Daignault, 2015) were conducted with child victims of sexual abuse, the others involved different types of traumatic events.

The conclusion of these studies is that TF-CBT and CBT are effective treatments in reducing posttraumatic symptoms (Caouette et al., 2021; Cohen & Mannarino, 1996, 1997; Hébert & Daignault, 2015; Hitchcock et al., 2022; Salloum, Robst, et al., 2014; Salloum et al., 2016) and PTSD diagnosis (Hitchcock et al., 2022; Salloum, Robst, et al., 2014; Salloum et al., 2016; Scheeringa et al., 2011) in young children with treatment gains maintained over the long term (follow-up range: 3–12 months).

Several studies show a significant improvement in comorbidities in children who received CBT treatment, including depression, oppositional defiant disorder (Hitchcock et al., 2022; Scheeringa et al., 2011), separation anxiety (Scheeringa et al., 2011), and specific phobia (Hitchcock et al., 2022). However, the odds ratios for comorbidities in the Hitchcock and collaborators study (2022) did not achieve traditional levels of significance, and the ADHD comorbidity did not seem to show improvement (Scheeringa et al., 2011).

RCTs showed that children in the control groups (treatment as usual or waiting list) did not improve (Cohen & Mannarino, 1996; Hitchcock et al., 2022; Scheeringa et al., 2011). The Stepped-Care model of TF-CBT did not appear inferior to TF-CBT in improving both PTSD diagnosis and posttraumatic stress symptoms, except in externalizing symptoms (Salloum et al., 2016).

TF-CBT emerges as the therapy with the greatest number of trials supporting its application for young children exposed to traumatic events. However, it remains difficult to establish a definite level of proof considering that most of the trials listed here evaluated different CBT protocols (PPT; Scheeringa et al., 2010; TF-CBT; Cohen et al., 2017; SC-TF-CBT; Salloum et al., 2017; CBT-3M; Hitchcock et al., 2022). However, we observe that the different protocols that the review allows to identify are all based on the same foundations. All protocols respect the general principles of the TF-CBT approach, with primary mechanisms of action having the aim to decrease the impact of cognitive distortions, to improve emotional regulation, to readapt behavioural responses, to help the children and their parents to make an adapted meaning of the trauma experienced, to help children decreased symptoms of trauma reminders and avoidance, to enhance coping skills, to improve the effectiveness of a social support (e.g. parental modules), and to restore children’s personal safety (Cohen et al., 2017). Considering the general therapeutic TF-CBT model, TF-CBT appears to meet the criteria of a level-2 or probably efficacious treatment for preschool-aged children with posttraumatic symptoms (McGuire et al., 2021; Southam-Gerow & Prinstein, 2014). To define TF-CBT with young children presenting posttraumatic symptoms as a level one or well-established intervention, two or more RCTs evaluating the same TF-CBT protocol would be necessary.

However, protocols cannot be evaluated in the same way if they are observed independently. With a good experiment showing that the treatment is superior to a control group (RCT: Cohen & Mannarino, 1996), a follow-up study, and one other trial with a good methodology, the TF-CBT model of Cohen & Mannarino (Cohen & Mannarino, 1993) could be considered a level-3, possibly efficacious treatment (Southam-Gerow & Prinstein, 2014) to treat young children with posttraumatic symptoms. With each one a good randomized controlled trial showing the treatment to be superior to a waiting list, the PPT, the SC-TF-CBT, and the CBT-3M protocols could be considered as level-3 or possibly efficacious treatments (Southam-Gerow & Prinstein, 2014) to treat young children with posttraumatic symptoms. With one single-arm interventional study, TF-CBT – AVI could be considered as a level-4 or experimental treatment (Southam-Gerow & Prinstein, 2014) to treat young children with posttraumatic symptoms.

3.1.2. Interventions focused on the child–parent relationship: child-parent psychotherapy (CPP) and parent-child interaction therapy (PCIT)

3.1.2.1. Child–parent psychotherapy

Child–parent psychotherapy (CPP) is the second most studied intervention that this review identified for the psychological treatment of young children with PTSD or posttraumatic stress symptoms. The systematized search identified four such studies.

CPP is a psychodynamic intervention and therapeutic treatment that focuses on the parent’s and child’s experience of their relationship and is considered here to be the most efficient mechanism to restore the child’s healthy developmental trajectory (Chu et al., 2021).

The efficacy of CPP for treating PTSD and posttraumatic stress symptoms in young children (range: 2–6 years old) is supported by one randomized controlled trial (Lieberman et al., 2005), one reanalysis of data (Ghosh Ippen et al., 2011) and two single arm interventional studies (Hagan et al., 2017; Weiner et al., 2009).

Of the four studies (Hagan et al., 2017; Lieberman et al., 2005), two were conducted with children exposed to interpersonal or marital violence, the others concerned different types of traumatic events.

The conclusion from these studies is that CPP is an effective treatment in reducing posttraumatic symptoms (Ghosh Ippen et al., 2011; Hagan et al., 2017; Lieberman et al., 2005) and PTSD diagnosis (Ghosh Ippen et al., 2011; Lieberman et al., 2005).

Also, the findings provide support for the efficacy of CPP with children between 2 and 6 years of age who experienced multiple traumatic and stressful life events (Ghosh Ippen et al., 2011). In a reanalysis of data from studies by Lieberman and collaborators (2005, 2006), Ghosh Ippen et al. (2011) have shown that children with four or more traumatic and stressful life events who were treated with CPP showed significantly greater improvements in PTSD symptoms, depression symptoms, PTSD diagnosis, number of co-occurring diagnoses, and behaviour problems compared to children in the comparison group. Findings also support the efficacy of CPP across racial groups and in foster care families (Weiner et al., 2009).

The different studies provide data on the improvement in child behavioural or emotional functioning (e.g. CBCL), however, no data is provided on the effect of CPP on comorbid disorders.

With a good experiment showing that the treatment is superior to a control group (RCT: Lieberman et al., 2005) and two other trials with a strong methodology, CPP could be considered a level-3, possibly efficacious treatment. One additional randomized trial controlling for PTSD symptoms and diagnosis in children would be necessary to consider CPP as a probably efficacious treatment (Southam-Gerow & Prinstein, 2014).

3.1.2.2. Parent–child interaction therapy (PCIT)

Despite a large number of articles discussing PCIT identified and reviewed during the selection stages, only one article met the criteria to be included in this systematic review. Important literature offers preliminary evidence of PCIT’s efficacy in children exposed to trauma (Warren et al., 2022), but most studies focus on the disrupting behaviours of children and on reducing future child maltreatment by caregivers, rather than on reducing posttraumatic symptoms.

PCIT is an evidence-based treatment model for young children with maladaptive behaviours due to different reasons, including trauma, oppositional defiant disorder (ODD) or attention-deficit hyperactivity disorder (ADHD).

The Trauma Treatment Training Center (TTTC) has examined the effect of parent–child interaction therapy (PCIT) on posttraumatic symptoms in young children (Pearl et al., 2012). This study has a pre-to-post design, without group comparison, and with 57 participants (mean age: 5.45 years) exposed to different types of traumatic events. Findings provide preliminary support for the efficacy of PCIT among young children with posttraumatic symptoms and dissociative symptoms.

Compared to other therapeutic models identified, no data confirmed the improvement in PTSD diagnosis with PCIT. Additionally, there is no data on therapeutic effectiveness on a comorbidity diagnosis.

To date, PCIT for posttraumatic stress symptoms in young children could be considered a level-4 or experimental treatment (Southam-Gerow & Prinstein, 2014). This conclusion does not concern the effectiveness of PCIT for treating disruptive disorders which is well supported. However, further studies that investigate the effectiveness of PCIT with a group comparison in an RCT and include specific scales for the evaluation of posttraumatic symptoms and diagnosis must be carried out in order to provide a better account of PCIT’s efficacy in treating PTSD symptoms and reducing PTSD diagnosis.

3.1.3. Early pathways, exposure therapy, EMI and EMDR

3.1.3.1. Early pathways

A randomized control trial was conducted to evaluate the effectiveness of a home-based, parent-and-child therapy programme specifically developed for toddlers and preschoolers living in poverty with trauma symptoms (Love & Fox, 2019). This treatment is based on the early pathways (EP) programme (EP; Fung & Fox, 2014; Harris et al., 2015) developed to address maladaptive behaviours in very young children living in poverty, but here it integrated new trauma-informed components (Love & Fox, 2019).

To address the specific needs of families living in poverty the authors explain that the protocol relies on an ecobiodevelopmental framework (Shonkoff et al., 2012), including the support of a safe and stimulating home environment with multiple strategies for assisting caregivers to accomplish this goal. Also, practical treatment strategies based on attachment theories and emphasize positive parenting strategies to address parent–child relationships are added to deliver a full system of parental support to decrease the environment toxic stress that could be associated with low-income conditions. Additionally, the EP treatment moves away from the contraindications usually encountered in care protocols, such as families where there is house-hold instability, serious ongoing conflict in the home, or basic needs are not being met. Finally, the treatment is delivered at home to facilitate the access. To address traumatic issues, the protocol includes many components adapted from existing programmes such as TF-CBT. In particular: a basic safety component, the trauma-informed limit setting strategies, the calming strategies, and the trauma narrative development.

Young children (range: 1–5 years old) were randomly assigned to an immediate treatment group (N = 32) or a waiting list control group (N = 32). Significant between-group differences on all posttreatment measures were found: challenging behaviours and symptoms of trauma decreased in children of the EP group, whereas children in the waiting list group continued to display their primary referral concern. After the waiting list group completed the EP treatment, significant improvements were found for both groups on all measures at six-weeks follow-up (Love & Fox, 2019). No data for the improvement in PTSD diagnosis or comorbidities were found.

With one good randomized controlled trial showing the treatment to be superior to a waiting list, the early pathways could be considered a level-3 or possibly efficacious treatment (Southam-Gerow & Prinstein, 2014).

3.1.3.2. Exposure therapy

Exposure therapy, or prolonged exposure therapy, is a trauma-focused intervention with components that include psychoeducation modules, anxiety management, and exposure (Rachamim et al., 2015). The feasibility of dyadic exposure therapy (DET), a developmentally adapted version of prolonged exposure therapy for adolescents (Foa et al., 2009), was evaluated in a randomized control trial (Rachamim et al., 2021).

The RCT compared DET with dyadic client-centred therapy (DCCT). Significant pre- to post-improvements on the DIPA and on the YCPC were found in the DET group. The results indicate that DET is an effective treatment in reducing posttraumatic symptoms and PTSD diagnosis in children between 2.5 and 5.5 years of age (M = 49.25 months). After the treatment, 83.3% of children in the DET group no longer met criteria for PTSD diagnosis. At the follow-up 3 months later, 100% of the children in the DET group no longer met criteria for PTSD compared to 66.7% in the DCCT group. The DET group was the only one to show a significant decrease in PTSD symptoms from baseline to 3-month follow-up. The study observes the number of events experienced by the children but does not describe the potential impact on treatment results. Likewise, the presence of comorbidities is described in pre-treatment, but there is no data on their improvement.

This RCT provides preliminary evidence for the efficacy of DET in young children with PTSD and posttraumatic stress symptoms, with good methodological criteria, but in a small sample (N = 12). This experiment does not seem to be sufficient to meet level-3 criteria, thus DET treatment could be considered a level-4 or experimental treatment (Southam-Gerow & Prinstein, 2014).

3.1.3.3. Eye movement desensitization and reprocessing (EMDR)

EMDR is a brief trauma-focused treatment for posttraumatic symptoms and PTSD in eight phases. A recent study provides preliminary evidence of the efficacy of EMDR in treating young children (aged 4–8 years) exposed to different types of traumatic events (Olivier et al., 2021). The EMDR treatment described in this study followed the standard protocol of Shapiro (2001) and the developmental modifications suggested by Tinker and Wilson (1999) and Greenwald (1999). Children completed six sessions of 1 hour, and no drop-out from treatment was observed. After the EMDR therapy, 85.7% of the children showed PTSD diagnostic remission. The results also indicate a decreased severity of PTSD symptoms, emotional problems, and behavioural problems. All gains were maintained at follow-up 3 months after treatment.

Results suggest that EMDR has a positive effect on anxious, depressive symptoms and anger symptoms (subscales of the TSCYC), but no data is provided on the effect of EMDR on comorbid disorder diagnosis.

This study has a multiple-baseline design and was conducted without group comparison and on a small sample (N = 9). For now, EMDR has a substantial evidence base for its effectiveness with children and adolescents, but it could be considered a level-4 or experimental treatment for young children (Southam-Gerow & Prinstein, 2014).

3.1.3.4. Eye movement integration (EMI) therapy

EMI is a brief trauma-focused treatment for posttraumatic symptoms that draws from the theories of Neuro-Linguistic Programming (NLP). Like EMDR therapy, EMI uses eye movements to reduce trauma symptoms through the integration of trauma memories. In EMI protocols, the eye movements tend to be smoother and not only horizontal.

In terms of research, trials with this therapy are quite recent. However, certain changes have already been proposed to adapt it to the youngest children. In an exploratory study with a small sample (N = 12), this method was identified as a potentially effective strategy for young children (range: 5–7 years old) with posttraumatic symptoms (Van der Spuy & van Breda, 2019). The study results show a significant reduction in all but one (sexual concerns) symptom of posttraumatic stress measured by the TSCYC. No results are provided for PTSD diagnostic improvement.

It seems that the aim of the study was to explore the feasibility of EMI in early childhood, and to explore whether this therapy could achieve rapid results. However, the children completed only one session, and only one rating scale was used.

The study used a mixed-method approach, with a pre-to-post design and without group comparison. EMI could be considered a level-4 or experimental treatment for young children (Southam-Gerow & Prinstein, 2014). We suggest that clinical studies be carried out with stronger methodological criteria (e.g. larger sample, children not exclusively from a private practice, a group comparison, more measurement scales and in particular a diagnostic instrument). These methodological improvements would provide clearer results on the effectiveness of this method with young children.

3.1.4. Synthesis

This review identified 17 articles reporting on the efficacy of 11 protocols of individual therapy for treating PTSD or posttraumatic symptoms in young children. In each study, the authors mentioned the importance of treatment protocols specifically adapted to the needs of young children.

Important methodological differences were found between the 11 care protocols identified, such as the number of sessions required (from three face-to-face sessions to one year of weekly sessions), but also the components and the theoretical background (e.g. parent–child relationship, cognitive and affective skills of the child, the need for a narrative of the traumatic story, etc.). Table 3 summarizes the key points of each intervention.

Table 3.

Protocols and theoretical background.

Protocol	Number of sessions, focus and actions	Indications	Identified studies
TF-CBT Cohen & Mannarino protocols Reference manuals: Cohen & Mannarino, 1993 Cohen et al., 2012, 2017	Number of sessions: 12–15 sessions Management of affective, behavioural, biological, cognitive, and social dysregulations through different modules: - Stabilization (psychoeducation, parenting skills, relaxation, affect modulation). - Trauma narration and processing. - Integration and consolidation (in vivo mastery, child-parent sessions, safety enhancement). Protocols include adaptations for children 3–17 years old.	Designed to treat different types of trauma exposure but only tested on victims of sexual abuse.	3 studies identified  =  Cohen & Mannarino, 1996, 1997; Hébert & Daignault, 2015.
TF-CBT PPT protocol Reference manuals: Scheeringa et al., 2010	Number of sessions: 12 sessions Management of affective, behavioural, biological, cognitive, and social dysregulations through different modules: psychoeducation, behaviour management of defiance, identification of feelings, relaxation exercises, telling the story (narrative exposure), prevention. Specially created for children from 3 to 6 years old.	Different types of trauma exposure	1 study identified  =  Scheeringa et al., 2011
SC-TF-CBT Reference manuals: Salloum, Scheeringa et al., 2014	Number of sessions: 3–12 sessions Based on classic TF-CBT components with relaxation strategies and trauma exposure, but aiming for greater feasibility by adapting the modules to parent-child sessions that can be completed at home in Step One. The role of parents is essential. 3 therapist-led sessions + homework, phone support, and psychoeducation through a website (Step One ∼ 6 weeks) 9 TF-CBT sessions (Step Two for non-responders to step one ∼ 9 weeks) Protocols can be offered to older children, but the strong parental component is ideal for children under 6 years old.	Different types of trauma exposure	2 studies identified = Salloum, Robst, et al., 2014; Salloum et al., 2016.
CBT 3M Reference manuals: Goodall et al., 2017 available online (https://c2ad.mrc-cbu.cam.ac.uk/resources/)	Number of sessions: 12 sessions TF CBT approach based on PPT but with a strong focus on three cognitive components (3 M): - Cognitive restructuring of trauma Memories. - Challenging maladaptive cognitive appraisals (Meanings). - Remediating unhelpful coping strategies (Management). And less exposure modules compared to other protocols.	Different types of trauma exposure	1 study identified  =  Hitchcock et al., 2022
AVI + CBT Reference manuals: AVI: Moss et al., 2011 TF-CBT: Cohen et al., 2017 AVI + CBT: Caouette et al., 2021	Number of sessions: 12 sessions TF-CBT approach (involving psychoeducation, parenting skills, relaxation and affective modulation, trauma narrative and in vivo components) combined to an attachment video-feedback intervention (AVI) to deal with insecure attachment. In the positive video-feedback intervention, the parent and the child are filmed during semi-structured play, then the parent watches the film sequences, and the clinician reinforces parental positive and sensitive behaviours.	Sexually abused preschoolers	1 study identified = Caouette et al., 2021
CPP Reference manuals: Lieberman et al., 2015	Number of sessions: ∼ 50 weekly sessions for one year Relational treatment to improve the parent/child relationship (secure attachment) by helping parents to create emotional safety for the child with appropriate protective behaviours and to prevent/halt developmental delay. Intervention modalities: translating behavioural meanings using play, body sensations, physical contact and language. Specially designed for children under 6 years old.	Indicated in case of exposure to domestic violence	4 studies identified  =  Lieberman et al., 2005; Ghosh Ippen et al., 2011; Hagan et al., 2017; Weiner et al., 2009
PCIT Reference manuals: Eyberg & Funderburk, 2011 http://www.pcit.org/store/c2/Manuals_and_Handouts.html	Number of sessions: ∼ 15 sessions Relational and dyadic treatment based on attachment theory, social learning, play therapy, and parenting styles. Specially designed for children under 6 years old with maladaptive behaviours.	Indicated in case of maladaptive and disruptive behaviours	1 study identified  =  Pearl et al., 2012
Trauma-focused Early Pathway Reference manuals: Love & Fox, 2019 www.marquette.edu/education/early-pathways	Number of sessions: 16 weeks depending on the individual needs of the child and family. Home-based parent-child therapy based on trauma-informed and TF-CBT components (e.g. building safety feelings, calming strategies, trauma narrative development) added to EP components (e.g. strengthening the parent-child relationship through child-led play, improving parenting skills and strategies, reinforcing the child’s pro-social behaviours and reducing the child’s challenging behaviours). Specially designed for preschoolers living in poverty.	Indicated in case of trauma symptoms	1 study identified  =  Love & Fox, 2019
Dyadic Exposure Therapy Reference Manuals: Rachamim et al., 2015 Rachamim & Mirochnik, 2014	Number of sessions: 15–17 sessions The protocol is based on the importance of confronting painful memories to regulate reactions to trauma. Treatment involves calm breathing techniques, in vivo exposure and revisiting the traumatic memory to correct erroneous expectations and maladaptive beliefs. Specially designed for children under 6 years old.	Different types of trauma exposure	1 study identified  =  Rachamim et al., 2021
EMDR Reference manuals: Shapiro, 2001 Adaptations for children: Tinker & Wilson, 1999 Greenwald, 1999; Morris-Smith & Silvestre, 2022 Storytelling: Lovett, 2015	Number of sessions: ∼ 6 sessions Based on the idea that the cognitive, emotional, and somatic aspects of trauma memories are stored inappropriately in the memory. EMDR treatment includes methods to enhance safety feelings, cognitive restructuring, use of rapid eye movements (or other bilateral simulations) and a type of confrontation/exposure to memories of the traumatic event (or to parent storytelling for the youngest children) to correct and reprocess dysfunctional responses to trauma. Protocols include adaptations for children 2–3 years old, 4–6 years old and older.	Different types of trauma exposure	1 study identified  =  Olivier et al., 2021
EMI Reference manuals: Beaulieu, 2003	Number of sessions: ∼ 2–6 sessions Based on the principles of Neuro-Linguistic Programming. EMI is at the crossroads between neurotherapy and talking therapy. The theory suggests that eye movements are linked to cognitive and neurophysiological processes. Eye movements are used to facilitate access to the recorded multisensory and affective dimensions of the traumatic experience, then to facilitate access to the dimensions of the healing networks.	Different types of trauma exposure	1 study identified  =  Van der Spuy & van Breda, 2019

4. Discussion

None of the identified care protocols could be considered well-established or level-one treatments. If the disparity between protocols makes it difficult to evaluate treatment efficacy, particularly in the case of CBTs, it nevertheless bears witness to the constant efforts of health professionals to adapt to the specific needs of the youngest children.

4.1. The case of CBTs

Efforts seem to be constantly made to improve the applicability of TF-CBT to younger children. Designs notably attempt to address concerns about the generalizability and feasibility of TF-CBT with young children (SC-TF-CBT), to adapt models to specific needs like restoring secure attachment links (CBT combined to AVI), and to create developmentally adapted components (PPT).

The various CBT protocols focusing on trauma in young children now offer considerable adaptability to their needs. CBT protocols could be chosen by care professionals based on the child's different symptoms. For example, if the child presents numerous cognitive maladjustments, CBT 3M would be preferred; or, if the child presents an insecure attachment, AVI-CBT would seem more suitable. Efforts to improve and specify protocols have also been made to adapt to family constraints. A family unable to come regularly to a care centre, for example, could benefit from an SC-TF-CBT protocol requiring only three face-to-face sessions in Step One. The stepped care protocol could also allow a professional to meet more families and children in need. For a comprehensive treatment, TF-CBT protocols like PPT or the Cohen and Mannarino manuals offer the possibility of working step by step on each symptomatic component of PTSD, in 12 sessions.

Finally, while our review identified eight articles about CBTs that corresponded to our inclusion criteria, many other studies focus on the application and effectiveness of CBTs in the youngest children with PTSD, such as case studies about PPT (Puff & Renk, 2015; Scheeringa et al., 2007; Stephenson & Renk, 2019); case studies about TF-CBT (Goodall et al., 2017; Jørgensen et al., 2019); case studies about the SC-TF-CBT (Salloum, Robst, et al., 2014); studies including older children (Allen & Hoskowitz, 2017; de Roos et al., 2011; Deblinger et al., 1990; Deblinger et al., 2011; Kane et al., 2016; Salloum et al., 2022), and practiced in group sessions (Deblinger et al., 2001).

4.2. Consideration of the child–parent relationship

Efforts to meet the specific needs of the youngest children can also be seen in protocols that consider the high dependence of young children on their parents, the importance of the co-occurring severity of parent and child posttraumatic symptoms, and the importance of the attachment quality in regulating a preschool child (e.g. CPP, PCIT, DET, and CBT-AVI).

Studies reported here about the effectiveness of Child–Parent Psychotherapy support the value of the child–parent relationship as a change mechanism in alleviating the negative impact of traumatic events (Chu et al., 2021). CPP protocols have also demonstrated a positive behavioural impact over the long term (Lieberman et al., 2006), a positive impact on attachment security (Cicchetti et al., 2006; Lieberman et al., 1991; Stronach et al., 2013). Nevertheless, in this type of long-term intervention, early termination can undermine the effects of the treatment (Weiner et al., 2009), and these year-long trials may be impractical in most practice settings (Gleason et al., 2007; Rachamim et al., 2021). To date, there is no protocol update to guide a shorter treatment with CPP.

To address this, the PCIT and the DET protocols offer shorter-term dyadic interventions, and our review identifies preliminary evidence that these therapies may be effective for treating trauma symptoms in young children.

The DET protocol appears to be an interesting approach for parent–child dyads exposed to the same traumatic events and in which parents seem to be dealing with their own posttraumatic response. DET focuses on the PTSD symptoms of both children and caregivers and seems to improve the bidirectional effects of traumatic responses in dyads (Rachamim, 2017; Rachamim et al., 2021, 2015).

PCIT is one of the strongest evidence-based treatment models for young children with behavioural challenges, with treatment outcomes that include lower parenting stress, lower reoccurrence of abuse, and decreased problematic child behaviours (Warren et al., 2022). This therapeutic approach could be suitable for children whose behavioural problems are at the forefront.

4.3. The case of EMDR and EMI

This review made it possible to identify a recent study on the applicability of EMDR to very young children. EMDR is one of the most recommended therapies for treating PTSD in adults. Compared to TF-CBT, EMDR puts less demands on cognitive and verbal skills, and it seems particularly well-suited for young children with PTSD (Olivier et al., 2021).

EMDR also seems to be the intervention for young children that requires the fewest sessions to obtain a reduction of posttraumatic symptoms. In a study involving older children and comparing the effectiveness of EMDR and TF-CBTs, treatment results (symptom reduction) were achieved more rapidly in children in the EMDR group (de Roos et al., 2011).

Over the past few years, EMDR has gained support as a protocol for treating childhood trauma, especially in studies that involve young children and older children (de Roos et al., 2011; Hensel, 2009; Meentken et al., 2020, 2021), but also in studies with preschool children in group practice (Lempertz et al., 2020). Salloum, Scheeringa et al. (2014) explain that EMDR could have been provided as a short intervention in Step One, with TF-CBT in Step Two, in their stepped care protocol that aimed to improve the feasibility of interventions for treating PTSD in children. However, this choice was not retained because it required clinicians certified in two different approaches (TF-CBT and EMDR).

EMDR seems to be a brief treatment adapted to the cognitive and verbal abilities of young children. Furthermore, EMDR addresses many of the constraints of clinical practice. However, while efforts to adapt the protocols to young children have been carried out (Greenwald, 1999; Lovett, 2015; Morris-Smith & Silvestre, 2022; Tinker & Wilson, 1999), the effectiveness of these EMDR protocols has not yet sufficiently been demonstrated.

Only one study with a small sample examines the efficacy of EMDR as a treatment for young children (Olivier et al., 2021). Additional research will be needed to confirm and expand findings on the application of EMDR to very young children, especially since very specific adaptations by age group would be necessary (Tinker & Wilson, 1999).

These recommendations could also be made regarding EMI which also involves eye movement. Although EMI has a smaller research base than EMDR, efforts to address the adaptability of this therapy to young children appear promising. This therapy seems to offer the same advantages as EMDR for young children in that it does not have significant verbal or cognitive constraints. Today, adjustments proposed for young children are based solely on the study of Van der Spuy and van Breda (2019).

4.4. A specific protocol for low-income families

Finally, this review also identified adjustments to adapt therapies to young children with posttraumatic disorders living in low-income families.

Some treatment programmes require a stricter adherence to protocol manuals. The Early Pathways protocol with trauma components was therefore specifically designed by Love and Fox (2019) to provide the greater flexibility needed to work in the context of families living in poverty and to make it more practical for families experiencing ongoing stress.

The early pathways (EP) programme was developed to address significant behaviour problems in very young children living in low-income families and has already demonstrated primary proof of its effectiveness in randomized controlled studies (Fung & Fox, 2014; Harris et al., 2015). Recently, EP has been updated to include practical treatment strategies based on attachment and trauma theories. Once again, this work demonstrates a constant effort to improve and tailor protocols to the needs of the children and their families.

5. Recommendations for future research

Several studies reviewed did not offer follow-up assessments months after the intervention, or follow-ups were conducted only three to six months after the treatment. We therefore do not know the long-term effects of the treatments being tested, yet this knowledge could appear to be of capital importance since these are treatments offered during an important developmental period of childhood.

Moreover, throughout the review, we emphasize that treatments for young children (under 6 years of age), should be adapted to the developmental specificities of this population. The protocols listed by the review are described as specifically adapted, or having been modified, to meet the constraints and requirements of early childhood (e.g. dependency on adults, cognitive, social, and emotional abilities). However, a major issue is that the authors do not specify whether they evaluated the capacities of children to understand the therapeutic techniques used. A single study (Scheeringa et al., 2011) has determined that most children were able to understand and complete the treatment protocol with treatment fidelity measures.

This question of children's ability to understand treatments is even more relevant for studies that included children under three years of age (Hagan et al., 2017; Love & Fox, 2019; Rachamim et al., 2021; Weiner et al., 2009). In fact, below the age of three children’s language and cognitive abilities are still considerably limited. Furthermore, we still have insufficient information about PTSD symptom presentations during the first three years (De Young & Landolt, 2018) and we cannot determine whether current diagnostic algorithms adequately capture PTSD in younger children (from 0 to 3 years). Even in the preschool age, the assessment of PTSD remains greatly complicated due to the children's level of cognitive development (Woolgar et al., 2022), making the assessment dependent on caregiver report. The younger the children, the more limited their cognitive abilities will be, the greater their dependence on parents will be, and the more complex the assessment of their symptomatology will be.

Therefore, further research should analyse whether children can understand and cooperate with treatment components through treatments fidelity measures. Because there is a large difference in abilities (e.g. verbal) between children in early childhood, these data could account for age as a moderator. In addition, research on the treatment of posttraumatic symptoms in children under 3 years of age should include analyses of age as a moderator for treatment outcomes, should use assessment methods based the most recent diagnostic algorithms and, finally, describe how younger children respond to the assessment.

Finally, while this review focused on the posttraumatic stress disorder, it seems essential to consider comorbid disorders (Scheeringa & Zeanah, 2008). Future research could identify more clearly which protocol could deal effectively with comorbid issues and improve patient referral depending on the dominant symptomatology. Also, it would be interesting to see more studies on possible counter-indications to the application of the protocols.

6. Limitations

This review finds its main limitations in its exclusion criteria. The fact that studies with samples of older children (over 8 years old) were not included, even if age is used as a moderator, deprived us of data. Nevertheless, a clarified and specific population is important to ensure a strong methodology (Southam-Gerow & Prinstein, 2014) and we were looking for protocols specific to the needs and abilities of younger children (under 6 years of age). Well-constructed studies published in languages other than English also had to be set aside (e.g. Bourgou et al., 2020). Finally, this research does not offer a quantitative comparison of the effectiveness of treatment methods.

7. Conclusion

In the absence of international recommendations, it was important to investigate interventions for young children with PTSD and posttraumatic symptoms. This review identifies 17 studies and 11 protocols designed for the treatment and management of posttraumatic symptoms in young children, which showed initial evidence of effectiveness. This review allows childhood mental health workers to adapt their practice to the needs of this specific population by referring them to proven therapies for the treatment of posttraumatic symptoms in young children.

To propose care as close as possible to their needs, it is essential to consider the specific developmental characteristics of the young children, the feasibility of the intervention methods considering the family’s commitment, the child's symptomatology, and the type and number of occurrences of trauma exposure.

This research identifies specific protocols for low-income families (EP), for children showing a predominance of behavioural problems (PCIT), specific protocols for intra-family violence and seeking to re-establish secure attachment (CPP, CBT + AVI), and protocols allowing joint parent–child improvement of traumatic symptoms (DET, CPP). Also, the review identifies protocols aimed at resolving step-by-step cognitive, behavioural, biological, and emotional trauma-related disorders (TF-CBTs, EMDR), which are short-term therapies, and whose recent research focus on feasibility (SC-TF-CBT). Constant efforts seem to be made to provide specific care for younger children suffering from posttraumatic consequences.

However, while the field has made considerable progress there are some limitations with the existing research that are worth noting and further issues should be addressed in future research. Therefore, while this review focused on presenting treatments that have reported preliminary evidence of effectiveness in treating young children with posttraumatic symptoms, obtaining more data on treatments that may not be effective would be of capital importance. At the stage of selecting studies, no article was excluded on the criterion of ‘non-significance’. The only protocol for which we observe non-significant results that have been published is the dyadic client-centred therapy which is described in the article that presents the dyadic exposure therapy (Rachamim et al., 2021). This is also the only protocol for which we noted that it did not have a requirement for the presentation of trauma focus components. If more articles reported on treatments that are not effective in early childhood posttraumatic symptoms, we could describe what the essential components are for effective trauma-focused treatment.

To date, no treatment can currently be identified as a level-one evidence-based treatment (Well-Established Treatment). In order to provide international recommendations, additional research will be necessary to confirm current findings on the application of therapies to very young children with PTSD or posttraumatic stress symptoms.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data are available within the article and on request from the first author.