From childhood struggles to adult strains: A systematic review of the impact of adverse childhood experiences on psycho-emotional functioning, pain outcomes, and quality of life in populations experiencing chronic pain

Abstract

Adverse childhood experiences (ACEs) are well-documented risk factors for later health problems, such as chronic pain and mental illness. We aimed to synthesise the impact of childhood trauma on psycho-emotional disorders, pain perception and cognitions, and quality of life in individuals with chronic pain. A systematic review was conducted following PRISMA guidelines for systematic reviews and meta-analyses. Eligible studies were identified by searching PubMed, PsychINFO, Embase, and Web of Science, with publication dates from 1988 to April 2023. Inclusion criteria were formulated according to the PECOS framework, and relevant research articles were screened for inclusion. Evidence from 18 studies highlights the significant impact of ACEs (and their typologies) on patients’ psycho-emotional well-being, pain outcomes, and overall quality of life, with a cumulative effect emerging. However, significant methodological limitations, such as the lack of standardised measures to classify childhood adversity, prevent us from drawing definitive conclusions about the reported associations. The findings underscore the importance of integrated approaches to pain management that centre on the patient’s life history and psycho-emotional status. Future research should address current limitations to strengthen our understanding of the role of ACEs in chronic pain research.

Introduction

Chronic pain (CP) is a major public health burden with serious consequences for patients’ mental and physical well-being, quality of life, and socioeconomic stability. ¹ CP affects one in four Europeans making it a leading cause for long-term disability, yet only a limited number of patients receive adequate medical care from pain specialists.^2,3 The negative emotional and sensory experience associated with potential or actual tissue damage highlights the multidimensional nature of CP, which is influenced by a complex interplay of biological, psychosocial, and behavioural factors.^4,5 Understanding these multifaceted elements is essential to developing effective interventions and strategies to reduce the far-reaching consequences of the disease.

Research consistently depicts high rates of mood and anxiety disorders in diverse populations with persistent pain, emphasising the crucial link between them. Evidence from a range of somatoform and musculoskeletal pathological conditions shows considerable variability in the prevalence of mood disorders, including major depressive disorder (ranging from 2% to 61%), dysthymia (1% to 9%), and bipolar disorder (1% to 21%). ⁶ Similar results emerged in patients with comorbid anxiety disorders, with prevalence rates reaching up to 10% for generalised anxiety disorder, 28% for panic disorder, 8% for agoraphobia, and 23% for post-traumatic stress disorder. ⁶ Within a biopsychosocial framework, psycho-emotional factors are recognised as important contributors to persistent pain, with strong empirical support for a well-defined bidirectional relationship between them.^7,8 As such, while pre-existing mental health diagnosis (e.g. anxiety or depression) can increase the risk for developing CP, ⁹ persistent pain may result in the development of mood and anxiety disorders. ¹⁰ Distinguishing between primary mood and anxiety disorders co-existing with pain and cases where pain is primary can help in identifying the patterns of comorbidity with a view to developing effective treatments. The psychological concept of adverse childhood experiences (ACEs) has gained significant attention within CP research and practice. ACEs are traumatic events associated with maltreatment before the age of 18 years, including physical, sexual, and psychological abuse, and neglect. ¹¹ These events can occur directly through exposure with a caregiver or indirectly through an individuals’ living environment (i.e. domestic violence, parental death, and mental illness). Each year, approximately one billion minors experience some form of adversity, with annual healthcare costs related to ACEs amounting to €487 billion across Europe. ¹² Systematic reviews and meta-analyses provide a strong relationship between ACEs and CP in adults, thus justifying the inclusion of such experiences in pain management strategies. ¹³ Accordingly, childhood adversity is a well-established contributor to later psychopathology, including mood and anxiety disorders, ¹⁴ PTSD, ¹⁵ bipolar and psychotic disorders, ¹⁶ substance-use disorders, ¹⁷ as well as self-harm and suicidal behaviours. ¹⁸ Given the profound impact of ACEs on individuals’ mental health, researchers have recently proposed that poor mental health may mediate the relationship between ACEs and CP. ¹³

ACEs are proven risk factors for CP and mental health conditions. Given their dynamic role in pain’s multidimensional aetiology, this study aims to summarise the existing literature regarding their impact on psycho-emotional state, subjective pain measures (i.e. pain perception and cognition), and quality of life in patients with CP. A secondary aim was to synthesise whether the type and frequency of ACEs influence patients’ psycho-emotional state, subjective pain measures, and quality of life. Finally, we aim to determine whether previous researchers have demonstrated a mediating effect of psycho-emotional variables on the ACE-pain relationship. By addressing this research gap, we want to illuminate the complex interplay between the variables of interest. The systematic review protocol is registered with INPLASY, an international platform for systematic reviews and meta-analyses (DOI:10.37766/inplasy2024.2.0023).

Methods

To ensure a high-quality selection, we include studies from 1998 onwards that examined ACEs as defined by Felitti and colleagues. ¹⁹ This definition includes 10 categories of ACEs, such as abuse, neglect, household dysfunction, and parental separation, in relation to lifelong physical and mental health burden.

Inclusion/exclusion criteria

Eligibility criteria were formulated according to the PECOS framework (Participants (P), Exposure (E), Comparison (C), Outcome (O), and Study Design (S)). ²⁰ The target population consisted of adults aged 18 years and older, suffering from persistent musculoskeletal disorders (e.g. back pain and neck pain) or chronic pain conditions lasting at least 3 months (e.g. migraine and fibromyalgia). Selected articles reported exposures to ACEs, including direct types (e.g. physical abuse/neglect), alone or with indirect types (e.g. domestic violence and parental death/separation). Selected studies reported psycho-emotional disorders (e.g. depression, anxiety, and/or post-traumatic stress disorder) and measured pain outcomes in terms of sensory (e.g. pain intensity) and cognitive (e.g. pain catastrophizing) factors, along with quality of life (QoL). This analysis is based on observational studies conducted in the general population or primary care settings, including cross-sectional, case–control or cohort studies (retrospective or prospective, longitudinal and population-based), and exploratory studies using quantitative sensory tests. Studies reported in English or French were considered eligible for inclusion. Finally, studies focused on non-adult populations, adverse experiences in adulthood without addressing ACEs, pain reflecting a tissue injury component, high-risk populations (e.g. homeless and prisoners), single-case studies, randomised controlled trials, animal research, as well as systematic reviews, meta-analyses, grey literature, dissertations, theses, conference proceedings, and books, were excluded.

Research strategy

In accordance with our research criteria, we searched for relevant articles in four databases known for their comprehensive coverage of biological and psychological literature: PubMed, PsychINFO, Embase, and Web of Science.

The search terms used were as follows:

• (1) (“Chronic Pain” OR “Pain Chronic” OR “Widespread Chronic Pain” OR “Chronic Pain Widespread” OR “Chronic musculoskeletal pain”).

• (2) (“adverse childhood experience*” OR “adverse childhood trauma*” OR “childhood trauma*” OR “traumatic childhood experience*” OR “childhood traumatic experience*” OR “adolescent trauma*” OR “Early Life Stress” OR “life stress early” OR “ACEs” OR “childhood adversit*” OR “Physical Abuse” OR “Physical Neglect” OR “Emotional Abuse” OR “Emotional Neglect” OR “Sexual abuse” OR “Physical punishment” OR “Physical torture” OR “Parental substance misuse” OR “Parental substance abuse” OR “Mental illness” OR “parental addiction*” OR “Domestic Violence” OR “Intimate Partner Violence” OR “Parental separation” OR “Parental divorce” OR “Family dysfunction” OR “Parental death” OR “Parental Incarceration” OR “Foster Home Care” OR “Poverty” OR “Racial segregation” OR “Social Discrimination” OR “Bullying” OR “Community violence” OR “Social Isolation”).

• (3) (“psychological disorder*” OR “emotional disorder*” OR “Depression” OR “Anxiety” OR “psychological distress” OR “Perceived distress” OR “Post traumatic stress disorder” OR “PTSD” OR “traumatic memor*” OR “Traumatic stress” OR “retraumatization” OR “retraumatisation”).

• (4) (“Pain Perception” OR “pain intensity” OR “pain affect” OR “pain interference” OR “Chronic Pain Acceptance” OR “pain belief*” OR “pain cognition*” OR “perceived life control” OR “fear avoidance” OR “pain disability”).

• (5) (“Quality of Life”).

The final search equation was constructed as follows: Articles containing search terms from category 1 AND search terms from category 2 AND (either search terms from category 3, or those from category 4, or those from category 5).

Screening and data extraction

The review was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines. ²¹ A widely used citation management system, namely, ZOTERO, was used to store all retrieved papers to ensure effective data handling and a streamlined research workflow. ²² Two collaborators (G.A and A.C) first removed all duplicates before applying a pairwise selection process to choose the suitable articles for inclusion independently. In this process, each collaborator independently screened the articles based on the title and abstract, followed by a full-text review. After the initial screening, the two collaborators compared their selections and discussed any discrepancies to reach a consensus. In cases where they could not agree on an article’s inclusion or exclusion, a third author (C.R.) was consulted to help resolve the disagreement and make the final decision. This pairwise approach helps ensure that the selection process is thorough and unbiased, improving the reliability and consistency of article inclusion.

Data collection

The following characteristics were extracted from the articles: authors’ names, country, study type, cohort size, demographics, types of chronic pain studied, types of adversity examined, and ACE assessment tools. These data can be found in Table 1.

Table 1.

Study characteristics.

Author	Country	Study type	Cohort size (controls)	Demography	Chronic pain	Type(s) of adversity studied	ACE assessment tool
23	USA	Cross-sectional	237	100%F m.a 34.8 years +/−11.3 m.p.d 67.6 months +/−86.2	Back pain, headache/migraine and multiple pain	Sexual and/or physical abuse	DAQ
24	Canada	Cross-sectional	22,996	56.8%F m.a	Migraine	Parental domestic violence	CCHS-MH
				47.5 years +/−17.7 M		Physical abuse
				43.17% M m.a 46.4+/−17.3		Sexual abuse (touching only)
						Sexual abuse (forced sexual activity)
25	USA	Cross-sectional	1351	75.3% F	Fibromyalgia 19.6%	Emotional abuse	ACE-Q
				24.5% M	Back pain 13.5%	Physical abuse
				0.2% N.S n = 1351:	Headache/migraine 6.1%	Sexual abuse
				m.a. 49.0 years+/−15.44	Lower limbs 4.8%	Emotional neglect
				m.p.d 10.08 years ± 11.58	Neck 2.7%	Physical neglect
					Shoulder/arm/hand 2.1%	Parental separation
					Pelvic/abdominal 1.8%	Domestic violence
					Other 4.2%	Substance use
						Mental illness/suicide
						Incarceration
26	USA	Longitudinal	269	79.6%F	Multiple sites 28.6%	Emotional abuse	ACE-Q
				20.4%M n = 269:	Fibromyalgia 26.8%	Physical abuse
				m.a. 49.03 years ± 16.32	Back pain 14.1%	Sexual abuse
				m.p.d 9.98 years ± 12.06	Headache/migraine 6.7%	Emotional neglect
					Extremity pain 6.3%	Physical neglect
					Other 9.7%	Parental separation
						Domestic violence
						Substance use
						Mental illness/suicide incarceration
27	USA	Cross-sectional	326	100%F m.a. 40.30 years ± 5.85	Non-specified CP	Emotional abuse	ACE-Q
				m.p.d 15.81 years ± 9.92		Physical abuse
						Sexual abuse
						Emotional neglect
						Physical neglect
						Parental separation
						Domestic violence
						Substance use
						Mental illness/suicide
						Incarceration
28	Norway	Cross-sectional	n = 11 130 19.5% Sami	55.79% F	Neck and shoulders	Emotional, physical, and/or sexual violence	Unstandardised questionnaire
			80.5%no-Samis	44.21% M	Arms
					Back pain
					Lumbar
					Hips and leg
					Head
					Chest
					Stomach
					Pelvic
					Other
29	USA	Cross-sectional	164	64% F	Legs 63%	Sexual and physical abuse during ‘childhood’ (≤14 years old) and ‘adulthood’ (age ≥14 years old)	DAQ
				46% M n = 164:	Back 56%, hip/pelvis 54%, or arm/shoulder 43%
				m.a. 38 years
				m.p.d
				5 years ±6.8 months.
30	Austria	Cross-sectional	105	100%F m.a. CPP = 32.4 years ± 8.8 m.a. CLBP = 40 years ± 9.1	CPP 40.9%	Physical/sexual abuse	Unstandardised interview
			CPP(n = 43)	m.a. Control = 29.3 years ± 8.1	CLBP 38.10%
			CLBP (n = 40)
			Controls (n = 22)
31	USA	Cross-sectional	3081	85.7%F with ACEs m.a. 30.7 years ± 16.1	Spine pain (neck and back) 41.8%	Physical and sexual:	Unstandardised questionnaire
			15.25% with reported ACEs		Headache/facial pain 8.3%	Childhood (≤13 years)
					Joint pain (e.g. knees, elbows, and hip) 6.9%	Adolescence (13–18 years)
					Extremity pain (arms, legs, feet, hands) 7.3%	Adulthood (≥18)
					Neuropathic pain 18.4%
					Abdominal and genitourinary pain 8.2%
					Widespread musculoskeletal pain 4.4 %
					Cancer pain 0.6%
					Miscellaneous pain (e.g. chest, teeth, and ribs) 4.1%
32	USA	Cross-sectional	111	100%F m.a	Fibromyalgia 100%	Physical and/or emotional abuse	Part of a 90-min standardised initial fibromyalgia research clinic intake assessment
				47.33 years ± 10.98
33	Germany	Cross-sectional	234	55.98% F	CPPS 100%	Emotional abuse	ACE-Q
				44.02% M n = 234		Physical abuse
				m.a. 47.92 years ± 17.29		Sexual abuse
						Emotional neglect
						Physical neglect
						Parental separation
						Domestic violence
						Substance use
						Mental illness/suicide
						Incarceration
34	Brazil	Case–control	154	100%F m.a. 36.5 years	CPP 100%	Sexual/physical/emotional abuse	CTQ
						Physical/emotional neglect
35	USA	Case-control	835	53%F	UCPPS 100%	Emotional/physical/sexual abuse and traumatic events	CTES
			421 = urologic chronic pelvic pain syndrome (UCPPS)	47%M m.a. 43 +/− 15
			414 = control group/healthy individuals
36	Germany	Cross-sectional	203	NsCLBP group:	nsCLBP 100%	Sexual/physical/emotional abuse, physical/emotional neglect	CTQ
			176 = CP	7 3% F m.a. 56.73 years ± 10.19
			27 = control group	Control group:
				63.0%F m.a. 57.1 years ± 11.7
37	USA	Cross-sectional	949	100%F m.a 42 ± 11	Migraine alone 73%	Physical abuse, sexual abuse, and/or fear for life due to abuse	Unstandardised questionnaire
					Migraine and tension-type 11%
					Migraine and other headache 14%
38	USA	Cross-sectional	1348	88.1% F m.a.41 years	Migraine	Emotional/physical/sexual abuse	CTQ
39	USA	Cross-sectional	1348	88.1% F m.a. 41 years	Migraine	Emotional/physical/sexual abuse	CTQ
40	USA	Cross-sectional	1348	88.1% F m.a. 41 years	Migraine	Emotional/physical/sexual abuse	CTQ

Note. F: female; M: male; m.a.: median age; m.p.d: median pain duration; CPP: chronic pelvic pain; UCPPS: urologic chronic pelvic pain syndrome (UCPPS); nsCLBP: non-specific chronic low back pain; DAQ: Drossman Abuse Questionnaire; CCHS-MH: Canadian Community Health Survey – Mental Health; ACE-Q: Adverse Childhood Experiences Questionnaire; CTQ: Childhood Trauma Questionnaire; CTES: Childhood Traumatic Events Scale.

Qualitative synthesis

The themes of interest linking ACEs, psycho-emotional illnesses, pain outcomes, and QoL were identified independently by the two researchers (G.A. and A.C.) and then combined in a qualitative synthesis. Final agreement in classifying the discussion axes was reached by the contribution of all the authors.

Quality assessment

The risk of bias for cross-sectional studies was assessed using the AXIS assessment tool (including 20 questions) and the SIGN methodological checklist for case–control studies (including 15 questions).^41,42 The quality of longitudinal studies was assessed using the Johanna Briggs Checklist, with eight questions considering data related to period prevalence and various exposures. ⁴³ All studies were independently reviewed by two researchers (A.G. and A.C.); any inconsistencies detected were resolved by mutual agreement.

Results

Study selection

A total of 18 eligible studies with 46,632 participants were identified after screening titles, abstracts, and full-texts. The search strategy and the reasons for excluding records are presented in Figure 1.

Figure 1.

PRISMA diagram of systematic search results. PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

Study characteristics

Main characteristics for all studies can be found in Table 1. The majority of studies were cross-sectional.^{23–25,27–33,36–40} There were also one longitudinal study^26,35 and two case–control studies.^34,35 Objectives and main results of the studies are summarised in Table 2.

Table 2.

Main results of the studies.

Author	Research objectives	Results	Conclusions
23	To determine the relationship between a history of physical or sexual abuse, pain experience, and depressive symptoms in women with CPP.	After controlling for age and education, none of the ACEs was linked with pain intensity. However, sexual abuse in adulthood predicted greater pain-related disability. Physical and sexual abuse in adulthood was associated with higher levels of depression. Education level was significantly associated with pain intensity, pain-related disability, and depression.	ACEs and educational background play significant roles in shaping the mental health outcomes of women with CPP. Therefore, a history of physical or sexual abuse is more strongly associated with current depressive symptoms in women with CPP than the experience of pain itself. Additionally, educational achievement is strongly linked to both the severity of pain and the presence of depression in this population.
24	To determine the number and type of ACEs in relation to the prevalence of migraine across gender. To test whether these associations persist when controlling for a range of potential explanatory factors, including lifetime measures of depression and anxiety.	Exposure to ≥3 ACEs is associated with migraines for both genders, even after adjusting for lifetime depression and anxiety, health behaviours, and risk factors. Moreover, the relationship between ACEs and migraine was independent of lifetime depression and anxiety.	There is a robust and independent connection between a higher number of ACEs and the likelihood of experiencing migraines. The anticipated neurobiological changes caused by ACEs may not be restricted to those linked to emotional problems. However, it should be noted that present research is not designed to test biological processes and hence can only assess the impact of mental problems on health.
25	To investigate the prevalence of ACEs as well as the association between the number and type(s) of ACEs and pain-related outcomes in individuals seeking treatment at a multidisciplinary treatment centre for CP.	≥4 ACEs were linked to worse pain-related outcomes and lower QoL compared to individuals reporting fewer ACEs.	There is a profound negative impact of a higher number of ACEs, on pain-related outcomes, QoL, and mental health. Childhood neglect emerged as a significant factor for mental health outcomes, regardless of the total number of ACEs.
		≥3 ACEs were linked to higher anxiety and depression levels. Childhood neglect had a significant impact on mental health outcomes regardless of the number of ACEs. Significant differences were observed in the number and type of ACEs across genders but not in the relationship between ACEs and outcome variables.
26	To examine how ACEs may influence group and treatment-related differences in pain, functioning, and psychosocial disorders in adult patients participating in an interdisciplinary pain rehabilitation programme.	While high levels of ACEs were linked to greater levels of mental health and psychosocial adjustment challenges, participants reported significantly improved treatment outcomes regardless of whether they were exposed to zero, one, two, or three ACEs. There were no variations in treatment response between groups. Participants reporting higher ACEs had more dramatic thoughts about pain and decreased confidence in their abilities to cope with pain and engage in pain-related activities. Patients with a history of age-associated trauma had a higher level of psychosocial complexity, including increased depression and anxiety symptoms and a lower QoL related to mental health.	Even though there is a positive correlation between higher ACE counts and mental health difficulties, treatment outcomes improved significantly at all ACE counts, highlighting the significance of early detection, trauma-informed care, and focused mental health interventions to address age-related trauma, reduce anxiety and depressive symptoms, and enhance older adults’ mental health-related quality of life.
27	To examine the prevalence of ACEs in a large sample of mothers suffering from CP and their role on physical and emotional functioning.	Higher maternal ACE scores were linked to lower physical and social functioning, higher levels of anxiety and depressive symptoms, greater fatigue and sleep disturbances, and greater pain intensity and pain interference in mothers.	Results highlight the far-reaching impact of ACEs on various aspects of well-being and mental health in mothers experiencing CP.
28	To examine the relationship between violence in childhood and CP, in relation to the number of pain points and perceived pain intensity among Sami and non-Sami populations, and to explore ethnic differences.	Childhood abuse was associated with CP in several body parts, irrespective of ethnic origin and gender. Childhood abuse was also associated with multiple pain sites and higher pain intensity compared to participants not exposed to childhood abuse. However, these associations were weaker and also not significant among men Sami participants.	The observed relationships between childhood abuse CP representations and outcomes appear weaker and non-significant among Sami men, suggesting possible divergence in these relationships within this particular demographic group.
29	To examine the history of physical and sexual abuse, separating penetration from other types of sexual abuse in ethnically diverse men and women with CP and to see how different types of abuse and age of occurrence are related to the experience of pain.	All kinds of childhood maltreatment were linked to worse general health. Emotional pain was linked to all maltreatment scales in childhood and aggression in adulthood, but only for men in childhood. Disability was linked to both infancy and adulthood. Men who had been assaulted as children or adults exhibited greater levels of post-traumatic stress disorder.	There is a significant long-lasting impact of childhood adversity on various aspects of health and well-being, irrespective of type of ACE with distinct gender-related patterns in emotional and aggressive outcomes.
30	To examine the interrelationships among childhood abuse, depression, and stressful life events among women with CPP and CLBP, along with a control group of pain-free female subjects. To assess the potential interactions between these factors and their collective contribution to the occurrence of adult CP syndromes.	Childhood physical abuse and depression had a significant impact on the development of chronic pain in general, while childhood sexual abuse was only correlated with CPP. Severe sexual abuse in childhood was significantly correlated with depression, but physical abuse in childhood showed no such correlation.	Findings demonstrate the significant interactions between various types of childhood maltreatment, mental health conditions, and how they interact to cause chronic pain.
31	To determine the associations between lifetime abuse history and emotional distress, fibromyalgia-related pain severity and interference, and physical functioning in populations experiencing various types of CP.	Childhood maltreatment was associated with higher levels of depression, anxiety, physical dysfunction, pain intensity, pain interference, catastrophizing, and higher fibromyalgia symptom scores. The indirect effects of each comparison group on pain intensity through depression were statistically significant, supporting the idea that depression mediates the relationship between maltreatment and pain intensity. The indirect effects of each comparison group on maltreatment were statistically significant, demonstrating that depression mediates the relationship between maltreatment and physical functioning. The indirect effects of each maltreatment comparison group were statistically significant, demonstrating that anxiety mediates the relationship between maltreatment and pain intensity. The indirect effects of each comparison group were statistically significant, demonstrating that anxiety mediates the relationship between maltreatment and physical functioning.	Findings from mediation models provide credence to a novel biopsychosocial paradigm in which the relationship between pain and abuse is significantly influenced by the interaction between fibromyalgia and emotional distress. The mediation of greater pain morbidity in people with a history of abuse is due to the presence of a concentrated pain phenotype.
32	To measure the impact of ACEs on pain sensitivity and other pain outcomes in women with FM.	There is a significant relationship between ACEs and measures of pain perception and sensitivity (i.e. decreased pain tolerance, both in terms of overall pain threshold and number of tender points, was associated with a history of physical abuse, even after adjusting for BMI, pain catastrophising, and depression). Childhood abuse was significantly associated with an increase in physical and mental fatigue. Symptoms of fatigue and depression were associated with psychological abuse during childhood more than physical abuse. No association was observed between ACEs and sleep.	These results highlight the diverse impact of ACEs on pain perception, fatigue, and mental health outcomes.
33	To determine the nature and frequency of ACEs among patients with CPP and to investigate the relationship between ACE severity, somatic symptoms, psychological factors, and pain intensity.	More than twice as many reports of emotional abuse and neglect as of physical abuse and neglect (17.1% vs. 37.2%) were reported. Compared to those reporting no ACEs, ≥3 ACEs were associated with lower physical QoL. Depression was significantly predicted by ACE severity while somatic symptoms and depression were predictors of pain intensity. Depression partially mediated the relationship between ACE severity and pain intensity.	ACEs, depression, and somatic symptoms are significant factors to be considered in the assessment and management of CPP.
34	To determine the prevalence of child physical, sexual, and/or emotional abuse and neglect experienced by women with CPP and whether these events are associated with symptoms of pain, anxiety, and/or depression.	All types of childhood maltreatment were not independently associated with the development of CPP. Although they did not affect outcome, compared to the control group in the CPP group childhood maltreatment scores were higher and have been positively linked to depression and anxiety.	Although ACEs seem to not have a direct effect on CPP, the data suggest that they may have an indirect effect on mental health outcomes. More research is needed in the complex relationship between ACEs and CPP pathophysiology.
35	To determine how self-reported ACE severity is associated with pain and urinary symptoms in UCPPS, comorbid physical, and psychological health factors, including a variety of measures of negative mood and stress, somatic/functional symptoms, and likelihood of symptom improvement/worsening at 1 year follow-up.	ACE severity was associated with higher pain comorbidity, greater levels of baseline depression, anxiety, perceived stress, pain catastrophising, functional symptoms, painful body sites, fatigue, sleep disturbance, and perceived physical well-being. Greater levels of ACE intensity were linked to greater intensity of genitourinary pain and urinary symptoms. Greater levels of ACE intensity were also associated with a lower likelihood of improvement in pain symptoms and a greater likelihood of worsening pain symptoms after 1 year, indirectly through lower perceived physical well-being. Poor physical well-being mediated the relationship between ACE severity and a lower likelihood of improvement in pain symptoms and a greater likelihood of worsening pain symptoms at 1 year.	These findings underline the significant and long-term influence of ACEs on several health outcomes in patients experiencing UCPP, highlighting the importance of including ACEs in the study and treatment of the disease.
36	To examine whether distinct types of ACEs are linked to specific changes in somatosensory function in individuals with nsCLBP.	Subjects with nsCLBP who have experienced emotional abuse may exhibit enhanced temporal summation. Regardless of the type of ACEs, child maltreatment was linked to increased sensitivity to deep pain while emotional abuse was linked to greater temporal summation of pain.	Results suggest that following ACE exposure biological mechanisms other than tissue damage-related ones may lead to long-lasting alterations in an adult’s somatosensory system.
37	To determine, whether the prevalence of ACEs is higher in women suffering from migraine and depression, as well as the effects of the degree of depression and the type and timing of the abuse.	Major depression was linked to multiple types of ACEs while this association depended on depression. ACEs were more frequently reported in women suffering from migraine and concomitant major depression than in those suffering from migraine alone. The link between childhood sexual abuse and migraine and depression was strengthened if the assault also occurred later in adulthood. Depression was worse if the abuse also occurred later in life.	It is important to consider the type and timing of ACEs to understand their impact on mental health outcomes, particularly in the context of migraine and major depression, and to highlight potential gender differences in these associations.
38	To examine the prevalence and severity of childhood abuse, the interdependence of types of abuse, and rates of revictimisation in adulthood.	Migraineurs who reported ≥3 ACEs were more likely to have been diagnosed with depression and/or compared to those who had not experienced ACEs.	All types of childhood abuse and neglect are strongly associated with past and present depression and anxiety, and the relationship strengthens as the number of types of abuse increases.
39	To assess the relationship between different types of ACEs and migraine characteristics, including type, frequency, transformation, disability, allodynia and age of onset.	Emotional abuse was associated with continuous daily headaches, severe headache-related disability, and migraine-associated allodynia. The association of maltreatment and headache frequency appears to be independent of depression and anxiety, which are related to both childhood maltreatment and chronic daily headaches.	Results highlight the distinct and direct impact of emotional abuse on headache-related outcomes.
40	To assess, in a clinical population with migraine, the relationships between different types of childhood abuse and neglect and comorbid pain conditions. To examine the mediating role of depression and anxiety disorders in the relationship between childhood maltreatment and migraine comorbidities.	A stronger relationship was observed between ACEs and pain in people who reported multiple pains and multiple types of ACEs. Emotional abuse, physical abuse, and physical neglect were linked to higher prevalence of co-occurring disorders.	This finding suggests that, in migraine sufferers, maltreatment in childhood may be a risk factor for the development of comorbid pain disorders.

Note. CPP: chronic pelvic pain; CP: chronic pain; QoL: quality of life; ACEs: adverse childhood experiences.

Measurement approaches of chronic pain and associated sensory-cognitive outcomes

There was significant heterogeneity in the types of CP studied. Some studies focused on a single pain condition^24,32–40 while others studied multiple diseases.^23,25–31 Headaches and migraines were the most frequently studied conditions,^{24–26,31,37–40} followed by back pain,^{25,26,29–31,36} multiple pains,^25,26,29,31 fibromyalgia,^25,26,33 and chronic pelvic pain (CPP).^{23,30,33–35} The objectives and main results by study are summarised in Table 2. Further, various scales were used to assess sensory and cognitive pain outcomes resulting in a total of 29 tools^{23,25–29,31–37,39} (see supplemental document Table 2). The most studied pain outcomes were pain intensity, pain-related self-efficacy, catastrophising, cognitive difficulties, fatigue, physical function, pain-related disability, pain interference, pain detection thresholds, sleep, and somatic symptoms.

Measurement of adverse events during childhood and adolescents

Each study adopted a different approach to capture childhood adversity. Most researchers used scientifically validated questionnaires that assess ACEs retrospectively, while some studies employed semi-structured interviews or used self-developed questionnaires, resulting in 10 different tools (see supplemental document Table 1).

Psychological well-being measures

Various questionnaires were used to evaluate quality of life and psycho-emotional problems (see supplemental document Table 3). Depression was the most commonly studied mood disorder, assessed in 15 studies using six different questionnaires. Twelve studies used five different questionnaires to measure anxiety, and one study assessed PTSD and psychological distress separately. Finally, quality of life was assessed in five studies using three different questionnaires.

Quality assessment

The overall quality score for the cross-sectional studies was 15, 6/20. Two studies had a quality score of seventeen,^25,37 four scored sixteen,^23,24,28,31 three scored fifteen,^36,38,39 one scored thirteen, ⁴⁰ and another scored twelve ³³ (see Table 4 in supplemental documents). Both case–control studies received acceptable quality ratings^34,35 (see supplemental documents Table 5). Finally, the longitudinal study showed strong adherence to quality standards (see supplemental documents Table 6).

Childhood adversity and its impact on chronic pain: Unravelling sensory experiences, pain cognitions, interpretations, and long-term outcomes

There was considerable variation on the methods used to investigate the relationship between ACEs and CP. Researchers examined different types of childhood maltreatment, from specific ACEs to cumulative effects, along with various CP conditions and outcomes. Despite methodological differences, significant associations emerged between ACEs and sensory experiences, cognitive components of pain, interpretations, and long-term outcomes in CP. Among participants with CPP, ACE severity predicted higher pain intensity, ³³ somatic symptoms (i.e. physical symptoms that cannot be explained by an underlying medical condition),^33,35 and a higher number of painful body maps. ³⁵ ACE severity was further linked to higher levels of perceived stress, pain catastrophising, fatigue, and worse perceived physical well-being, suggesting a complex interplay of psychological factors, emotional responses, and overall well-being. ³⁵ However, in one study, there was no independent link between CPP and any form of childhood maltreatment, possibly due to the high prevalence of ACEs, even among the healthy control group. ³⁴ Furthermore, a cumulative effect of childhood adversity was observed across different CP conditions and outcomes, indicating heightened pain representations regardless of pain types. For example, in one study, patients with ≥3 types of ACEs had greater chances to develop migraine, with odds of 2.85 and 3.26 for women and men, respectively. ²⁴ Similar effects were observed for physical (i.e. pain duration and pain intensity) and cognitive aspects of pain (i.e. pain interference, pain catastrophising, and pain self-efficacy). ²⁵ Participants having ≥4 ACEs reported greater pain intensity, higher pain interference, and lower self-efficacy than those with fewer ACEs. Similarly, participants with ≥3 ACEs were more likely to report longer pain duration compared to those with no ACEs. No gender differences were found in these associations. Interestingly, when specific ACE categories were examined, the results remained statistically insignificant across genders, suggesting that pain representations are more influenced by combined effects than specific ACE typologies. Finally, a four-point threshold emerged between ACEs and pain catastrophising, with neglect linked to higher pain catastrophising. ²⁵ Researchers also highlighted a 3-point threshold between ACEs and cognitive representations of pain at the time of patients’ admission to a pain management program (including greater catastrophising and lower perceived self-efficacy towards pain). Interestingly, these results were insignificant at discharge suggesting the program’s effectiveness regardless of ACEs. ²⁶ The cumulative impact of adversity was further linked to CP onset, with participants experiencing persistent pain from childhood reporting more ACEs than those who developed CP in adulthood. ²⁷ In the same study, more ACEs correlated with lower physical and social functioning, greater pain intensity and interference, and higher fatigue levels.

Researchers also reported pain outcomes associated with specific ACEs. For example, one study found strong links between physical abuse, sexual abuse, and fear for life due to abuse to chronic headaches, with participants experiencing higher somatic symptom severity and headache-related disability. ³⁷ Even after controlling for depression, somatic symptom severity was independently associated with childhood adversity, suggesting that ACEs’ impact is independent of current depression states. Consistently, all five types of adversity were linked to transformed migraine (i.e. a progression from episodic to more frequent and severe headaches). ³⁹ Similarly, all ACEs except sexual abuse were associated with chronic migraines. Interestingly, emotional abuse showed the strongest association with chronic and transformed migraine, and it was the only factor marginally linked to CP disability. Further, physical abuse was related to more significant impairment in the language cognitive domain, suggesting an effect on language-related cognitive outcomes. ³² This may include difficulties in effectively expressing one’s feelings and experiences related to pain through language or verbal expression of pain. Physical abuse was also linked to both sensory and emotional aspects of pain, such as increased pain sensitivity, decreased pain tolerance ³² as well as higher levels of pain affect. ²⁹ Childhood sexual abuse was associated with emotional responses towards pain with sexual penetration, predicting greater pain affect and pain disability in men. ²⁹ This finding aligns with studies showing how unresolved trauma can trigger stronger emotional responses in subsequent situations. ⁴⁴ Therefore, men may have found a less stigmatising way to express this trauma through heightened emotional responses to pain.

One study used quantitative sensory testing (QST) to investigate the association between ACEs and changes in pain perception in individuals with non-specific chronic low back pain (nsCLBP). ³⁶ Individuals with ACEs exhibited reduced pressure pain thresholds (PPTs), indicating heightened deep pain sensitivity and mechanical hyperalgesia to deep-tissue stimuli. Similarly, individuals who experienced maltreatment had a higher wind-up ratio (WUR), indicating increased spinal excitability and sensitisation processes. Interestingly, there were no alterations in thermal pain thresholds, suggesting that childhood adversity mainly affects deep pain rather than surface-level sensitivity. Emotional abuse was linked to elevated WURs, indicating its unique impact on pain perception. The researcher conceptualised emotional abuse as a critical factor in sensory pain processing through participants’ heightened attention, feelings of helplessness, and magnification of pain-related worry.

Adverse childhood experiences as precursors: Exploring the interconnection between childhood adversity, chronic pain, and comorbid disorders

Several authors have identified associations between childhood adversity, pain, and multiple comorbidities in populations experiencing CP. Tietjen and colleagues first raised the issue of obesity, noting that 30% of their study participants had a body mass index (BMI) ≥30 kg/m². ³⁸ Obesity was common in participants with a history of emotional abuse as well as physical and emotional neglect. Although regression testing showed that obesity was not significantly linked to any childhood trauma, these results suggest a possible association between child maltreatment and obesity in populations experiencing chronic migraine. The same researchers highlighted that all five childhood adversities were significantly associated with an increased number of comorbidities in the same populations. ⁴⁰ After controlling for demographic and mental health factors, emotional abuse was independently associated with a higher number of pain conditions including irritable bowel syndrome (IBS), chronic fatigue syndrome (CFS), fibromyalgia (FM), and arthritis. Similarly, physical abuse was associated with the prevalence of arthritis, while physical neglect was linked to IBS, CFS, arthritis, and interstitial cystitis. Gender differences were reported, with emotional abuse and physical neglect in women linked to more comorbidities, such as endometriosis and uterine fibroids for physical abuse and uterine fibroids for emotional neglect. Finally, they were more likely to be diagnosed with chronic headaches compared to those with no comorbidities. Similarly, participants with ≥4 comorbid conditions were more likely to report transformed migraine than those having less than three comorbid conditions. Considering the role of ACEs in this context supports the view that individuals with CP and childhood maltreatment may be at greater risk of developing multiple chronic conditions. This was also the case in populations with CPP where higher levels of child maltreatment were linked to at least one comorbid pain. ³⁵ Further, a significant relationship was observed between ACEs and CP development in various body sites, independent of gender and ethnicity differences. ²⁸ Consistent with these results, widespread musculoskeletal pain was more prevalent in participants with child maltreatment, suggesting people with ACEs might be at greater risk for physical health issues (i.e. CP) in various body parts. ³¹ Lastly, child trauma was more prominent in individuals with fibromyalgia or multiple-site pain. ²⁵ Participants in these groups were less likely to report no ACEs and more likely to report ≥4 ACEs, indicating a link between childhood trauma and the development of CP disorders. This highlights the importance of considering both physical and psychological factors when assessing and treating these conditions.

Childhood adversity and its impact on psycho-emotional disorders and quality of life

In most studies, childhood adversity has emerged as a vulnerability factor for the development and maintenance of various psycho-emotional disorders, including depression, anxiety, and post-traumatic stress disorder (PTSD).^{23,25–27,29–35,37,38,40} More specifically, ACEs were linked to severe mental health outcomes in patients with persistent headache and migraine diagnosis, such as depression alone^37,40 or in comorbidity with anxiety. ³⁸ Their initial findings suggested a four-fold increase in the odds ratio between ACEs and depression. ³⁷ Similar associations were drawn between anxiety and/or depression and ACEs in populations suffering from CPP.^{23,30,33–35} Interestingly, childhood adversity emerged as a significant predictor for developing depression in adulthood, particularly in men. ³³ These findings suggest sex differences in response to childhood maltreatment and future mental health outcomes, which merit further investigation. Further, significant associations emerged between ACEs and higher levels of depression in patients with chronic low back pain, ³⁰ a finding later replicated among several chronic musculoskeletal conditions, including fibromyalgia,^31,32 persistent spinal and extremity pain, as well as facial and other pain (e.g. chest, teeth, and ribs). ²⁹ Consistent results were noted for both anxiety and depression outcomes, although the researchers did not specify the type of CP studied. ²⁷ More importantly, a dose–response relationship was established between ACEs and psycho-emotional disturbances with greater exposure to childhood maltreatment being associated with higher levels of anxiety and depression in different chronic pain samples.^25–27,35 Interestingly, individuals reporting ≥3 ACEs showed significantly higher levels of anxiety and depression,^25,38 further highlighting the role of cumulative adversity on psycho-emotional well-being.

Several authors have examined the differential effects of different types of ACEs on psycho-emotional problems. Results vary significantly depending on the questionnaires used to measure adversity and their methodological approaches. For example, sexual abuse was strongly linked to depression in one research while physical abuse was not. ³⁰ Similarly, higher rates of depression have been reported in female populations with CPP who had experienced physical or sexual abuse compared to their counterparts without such ACEs. ²³ Echoing these results, all types of childhood adversity were strongly associated with anxiety and depression among females with CPP providing a nuanced perspective on the mental health effects associated with maltreatment in this pain condition. ³⁴ In another study, sexual and physical abuse (assessed as a single category called ‘lifetime abuse’) were linked to had higher levels of reported anxiety and depression. ³¹ Although group comparisons were not studied, it is arguable that individuals with either form of childhood abuse may be more susceptible to mental illness, especially if they suffer from persistent pain. Similarly, sexual abuse was strongly associated with major depression, particularly when the abuse occurred before age of 12 years, highlighting the age of onset as a detrimental factor with a lasting impact on the mental health of people with chronic migraines. ³⁷ The same group further highlighted that all types of childhood maltreatment were significantly associated with past and current depression in populations with migraines and chronic headaches. ³⁸ Additionally, child neglect, either alone or in combination with household dysfunction, was linked to higher levels of anxiety and depression, ²⁵ while emotional abuse was correlated to depression. ³² Finally, one study evaluated the distinct effects of childhood subtypes on PTSD symptomatology. ²⁹ Researchers highlighted childhood molestation as a significant predictor in men. As such, men may suffer from unresolved emotional trauma manifesting as emotional distress to pain, possibly due to social expectations, shame, or a lack of appropriate coping mechanisms associated with male victims. ⁴⁵

Five studies have examined the impact of childhood maltreatment on patients’ quality of life (QoL).^25,26,29,35 Nevertheless, there is consensus that ACEs decrease perceived QoL regardless of pain diagnosis. More specifically, childhood adversity has been associated with worse perceived physical^25,33,35 and mental health-related QoL.^25,26,29 Similarly, a significant association emerged between ACEs and lower self-reported QoL related to general health, ²⁹ greater reported fatigue, and sleep disturbances. ³⁵ Findings from both populations with CP and healthy control groups showed that childhood maltreatment was associated with poorer perceived physical well-being and higher levels of fatigue and sleep disturbance. ³⁵ These results highlight the pervasive and long-lasting effects of maltreatment on mental and physical health, regardless of whether the victims are chronically ill or not.

Further, a dose–response relationship emerged between ACEs and QOL, with researchers indicating that higher ACE severity or a greater number of ACEs is closely linked to reduced physical and mental well-being, as well as poorer overall health.^29,35 Interestingly, a threshold of three ACEs was linked to lower levels of physical QoL ³³ and worse mental health impairment. ²⁶ Similarly, four or more ACEs were associated with significant mental health impairment and worse perceived physical health-related impairment. ²⁵ Only one study reported comparisons between QoL and different types of ACEs. ²⁵ Compared with those who reported no adversity or only household dysfunction during childhood, child neglect, alone or in combination with household dysfunction, was associated with greater self-reported mental health impairment. Additionally, compared with those who had suffered childhood abuse, participants reporting only childhood neglect had higher rates of perceived mental health impairment. In other words, childhood neglect alone, or in combination with dysfunctional family dynamics, significantly impacts QoL and often outweighs the effects of childhood abuse in terms of perceived mental health impairment.

Childhood adversity and chronic pain: The mediating role of psycho-emotional disorders

Only two studies have explored emotional disturbances as potential mediators in the relationship between ACEs and pain outcomes.^31,33 One study confirmed that both depression and anxiety fully mediated the relationship between ACEs and pain severity, and partially mediated the relationship between ACEs and physical functioning. These results suggest that ACEs may lead to greater emotional distress, which in turn can contribute to worse pain-related outcomes. ³¹ More importantly, these mediation models show that such dynamic interactions of multiple psychological and somatic variables may influence pain outcomes more than any single factor alone. Similarly, Piontek and colleagues (2021) tested depression, anxiety, and somatic symptoms (i.e. physical complaints without a known medical cause) as potential mediators between ACE severity and pain intensity. Depression emerged as a partial mediator, suggesting that other factors may also contribute to this relationship. Anxiety did not meet the necessary assumptions for mediation model testing; nevertheless, the inability of one study to test a particular hypothesis does not preclude the existence of such a relationship in other research settings. ³³

Distinct pathways also emerged through which ACEs affect pain and mental health outcomes across genders. ³³ More precisely, in men both somatic symptoms and depression mediated the relationship between ACE severity and pain intensity, suggesting that men exposed to serious ACEs are prone to worse mental health and psychosomatic responses, which in turn negatively impact their pain experience. In women, somatic symptoms had also a direct effect on pain intensity, but ACEs did not, on depression. These findings suggest that ACEs in women may lead to different coping mechanisms and, therefore, manifest in different ways other than depression (e.g. somatic symptoms and/or other forms of anxiety).

Furthermore, three studies considered depression and anxiety as control variables without explicitly testing for mediation effects.^24,39,40 Nevertheless, such studies are essential for understanding the broader research context and discussing potential confounding factors. In one study, emotional maltreatment was strongly linked to chronic migraine, transformed migraine, and age of headache onset even after adjusting for current depression and anxiety. ³⁹ Such findings highlight the direct impact of early-life emotional trauma on various headache conditions irrespectively of patients’ current emotional states. Accordingly, both emotional and physical neglect during childhood were independently linked to a higher number of pain conditions in adulthood, even after controlling for current depression and anxiety. ⁴⁰ Finally, researchers showed that individuals with migraines often experience comorbidity mental disorders (i.e. depression and/or anxiety), related to persistent pain. However, the link between ACEs and migraines remains significant, even after controlling for these psychological factors. ²⁴ This suggests that although such psycho-emotional disturbances can influence pain outcomes, they are not the primary reasons why ACEs leads to CP conditions like migraines.

Discussion

To the best of our knowledge, this is the first review to synthesise evidence from populations with CP on the relationships among ACEs, psycho-emotional disorders, pain cognitions/interpretations, and quality of life. In accordance with our first aim, the results show that childhood adversity has detrimental effects on patients’ psycho-emotional state, pain outcomes, and perceived QoL. Specifically, ACEs have been associated with increased somatic pain expressions (i.e. heightened pain intensity and sensitivity, increased responsiveness to pain in deeper tissues, more pronounced somatic symptoms, and multiple locations of pain) as well as adverse psychosocial consequences of CP (i.e. elevated levels of catastrophic thinking, higher self-reported fatigue, and diminished perceived physical well-being).^33,35,36 Most studies linked ACEs to poorer mental health outcomes and several psycho-emotional disorders such as anxiety, depression, and PTSD.^{23,25–27,29–35,37,38,40} Finally, ACEs were associated with lower perceived physical^25,33,35 and mental health-related QoL.^25,26,29 These findings align with a large body of literature that has consistently showed the long-term effects of ACEs on health and well-being across different populations, including those with CP.^13,46,47 Furthermore, in line with the second aim, which focused on whether the type and frequency of ACEs influence patients’ psycho-emotional state, subjective pain measures, and QoL, our synthesis shows that higher number of ACEs are associated with greater psycho-emotional disturbances, worse pain outcomes, and poorer QoL. A cumulative effect was also established between ACEs and a wide range of pain outcomes, including increased risk for longer pain duration, higher pain intensity and pain interference, as well as negative cognitive interpretations about pain (i.e. pain catastrophising and pain self-efficacy). These findings underscore that it is the accumulation of adversity which has the largest impact on CP outcomes regardless of pain type.^24–26 Similarly, a dose–response relationship was confirmed between childhood adversity, mood and anxiety disorders, and overall QoL, whereby patients who reported specific thresholds of ACEs had significantly larger levels of anxiety and depression, reduced physical QoL, and finally increased mental health impairment.^{25–27,29,33,35,38} Results are also in line with the existing literature about the cumulative effect of ACEs on physical and mental health problems across the lifespan.^13,46,47 While these findings highlight strong associations between childhood adversity, CP, and mental health outcomes, none of the included studies examined the biological mechanisms underpinning these relationships. Nevertheless, it is well-established that ACEs can result in allostatic overload – a state where prolonged or repeated stress exceeds the body’s capacity for recovery leading to dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis, a central stress-response system.^48,49 This dysregulation, characterised by impaired glucocorticoid feedback and heightened cortisol reactivity, affects brain regions such as the amygdala,^49,50 hippocampus,^51,52 and prefrontal cortex, ⁵³ which regulate both emotional^54–58 and pain processing.^55,59,60 Therefore, these changes may increase susceptibility to stress-related disorders (e.g. anxiety, depression, and PTSD) and CP through shared pathways of stress sensitisation and central nervous system hyperactivity.^61,62 Future research should explore these mechanisms in populations experiencing CP using mixed-methods approaches that integrate biological and psychological data to better understand the interplay between ACEs, mental health, and pain outcomes.

Further, our synthesis shows that different ACE typologies have distinct effects on mental health, pain outcomes, and QoL. Research highlighted that both physical^32,37,39 and sexual abuse^29,37 have key influences on CP outcomes. Various interpretations can be drawn on the relationship between ACEs and mental health, with evidence suggesting that age and gender disparities influence the onset of adversity.^29,38 Interesting associations emerged between depression and various types of abuse including physical,^23,31 sexual,^23,30,31,37 and emotional abuse. ³² Additionally, childhood molestation has been linked with PTSD in men. ²⁹ Importantly, child neglect, whether experienced alone or in combination with family dysfunction, plays a more critical role than child abuse in predicting worse anxiety, depression, and QoL, particularly in terms of reported mental health impairment. ²⁵ While biopsychosocial rehabilitation programs in populations experiencing CP have been shown to provide benefits for trauma-related outcomes, even without directly engaging in a trauma-focused intervention,^25,63 our results highlight the need for targeted and holistic approaches tailored to the specific nature of the adversity to achieve optimal outcomes. For example, those with a history of physical or sexual abuse may benefit more from trauma-informed pain management interventions or cognitive-behavioural therapies that address both emotional trauma and physical pain.^64,65 Similarly, attachment-based interventions and/or emotion-focused interventions focussing on emotional regulation and rebuilding trust could be particularly effective for individuals with emotional neglect, who often exhibit impaired emotion regulation and maladaptive schemas.^66,67 Incorporating such approaches will ultimately help foster resilience and improving both pain management and psychological well-being in individuals with chronic pain.

Finally, in accordance with the third aim, two studies partially supported that psycho-emotional disorders may mediate negatively the relationship between ACEs and pain outcomes.^31,33 Although depression emerged as a potential mediator, findings suggested other factors and pathways that may intervene between CP and ACEs. As such, future researchers should target other possible contributors between these variables.

As in any review, there are several methodological limitations. First, the majority of the research was based on retrospective data, relying on participants’ recall regarding traumatic experiences. Human memory is fallible, distorted over time, and it may be emotionally biased, making it even more susceptible to inaccuracies and recall bias. ⁶⁸ The same applies to self-report questionnaires measuring ACEs, subjective levels of pain, and QoL, where measurement bias could be introduced. As such, participants may respond based on personal interpretations, where cognitive processes during memory retrieval and judgment also play a role. The accuracy and reliability of the answers are also strongly affected by personality traits and current emotional states. ⁶⁹ Most studies included participants with specific CP conditions, predominantly women, which may limit the generalisability of findings across genders and other types of CP. Furthermore, gender differences were shown to have significant effects on mental health and emotional responses to pain, especially for male survivors of childhood maltreatment.^29,33 These results highlight the need for a more in-depth understanding of different experiences. Future researchers are encouraged to follow changes over time using longitudinal designs in order to capture the dynamic nature of gender-related factors. Furthermore, it’s critical to remember that there are several types of CP, each with its own unique features and mechanisms that could influence how ACEs affect people with persistent pain. These distinct characteristics and mechanisms require an adapted approach to understanding them, and future research should take advantage of interdisciplinary collaboration and condition-specific analyses. Another limitation could be the lack of longitudinal studies which prevents us from discussing potential causal relationships between ACEs, psycho-emotional difficulties, and the development of persistent pain.

It is also important to discuss our initial speculations to include some studies in this review.^24,38–40 More precisely, in one study, the diagnosis of CP was based on self-reported medical tools, which may not provide as accurate or detailed information as clinical assessments. ²⁴ Another study included participants with a diagnosis of chronic migraines, but also patients with migraines slightly below the standard criterion for this diagnosis (i.e. ≥15 headache days including at least eight migraine days during the last 3 months). ⁷⁰ However, we decided to include these findings to capture a wider range of experiences, including people with headaches on 13 or 14 days per month, to ensure a thorough examination of the impact of ACEs on the transition from episodic to chronic migraine.

There was also considerable variation in how ACEs were defined and assessed in terms of time, with some researchers reporting ACEs based on events that occurred before the age of 18, while others captured ACEs without defining an age range. This inconsistency is further complicated by several age classifications, such as adversity occurring before the age of 18, before 16, or within specific age ranges (e.g. 13 years or younger and 14 years or older). Additionally, few studies have studied the precise developmental stage at which ACEs occurred which is crucial for understanding their impact. Future research should classify ACEs more consistently in terms of duration and age of occurrence to improve the comparability of studies and the generalisation of results. It is also essential to explore the effects of ACEs at different developmental stages to understand how they may affect emotional regulation, brain circuitry, and behaviour across the lifespan.^71,72

Another significant concern lies in the quality of the tools used to capture adversity. While most studies used validated questionnaires, some researchers developed their own tools that, at the time of administration, had not been rigorously tested.^28,31,37 Since the psychometric properties of these tools are unestablished, we have concerns about the reliability and generalisability of their findings. Moreover, ACEs assessment using semi-structured interviews is taken into consideration.^30,32 While qualitative approaches ensure that the data is rich in context, they are, by definition, usually without standardisation and quantification, thus more susceptible to interviewer bias. ⁷³ Future research should prioritise the implementation of standardised methodologies to improve the accuracy and validity of findings, facilitating meaningful comparisons across different studies. Lastly, considering the variety of measures used to evaluate a wide range of ACEs, the cumulative effects discussed in this review need to be interpreted cautiously.^{24–27,33,35,38,40} In line with previous work, we argue against the assumption that different types of adversity have the same effects; rather, we need to explore the distinct processes underlying the influence of each type of adversity. ⁷⁴ Such an approach will allow better interpretations and help overcome current methodological and conceptual limitations in research on childhood adversity. ⁷⁵

Conclusions

ACEs significantly influence mental-health, pain experiences and overall quality of life in populations with CP. Our findings conceptualise ACEs as a critical psychological factor in assessing and managing the disease, highlighting the need for holistic pain management approaches, that prioritise the patient’s life history and psycho-emotional status. There is a clear need for better and more accurate ways to measure ACEs to deepen our understanding and produce more reliable, comparable results. This will facilitate the development of early preventive interventions and psychosocial support programs that will reduce the impact of childhood trauma and improve the quality of life of people living with chronic pain.

ORCID iD

Angeliki Gkiouzeli https://orcid.org/0000-0001-6273-5502