Table 1.

Characteristics of the study population, design and treatment intervention.

Study (author, year)	Study design	Population/type of Trauma	No of participants/Gender	Age	Additional Diagnosis	Exclusion Criteria	Duration and frequency of treatment/Neurofeedback Protocol/Sensor Placement	Adjunct interventions	Control Intervention
Peniston & Kulkosky, 1991	RCT	Vietnam combat veterans with PTSD	N = 29; 29 male	36.68 ± 2.72	Not reported	Psychotic symptoms; organic dysfunction	30 sessions of Alpha/Theta training, 5 days a week; 30 min session; Sensor placement: O1	Experimental group only: Pre-training: 8 × 30-min temperature biofeedback, autogenic training and rhythmic breathing technique. Both groups were on psychotropic medications: Tricyclic antidepressants, anxiolytics and antipsychotics.	Traditional medicine: psychotropic medications combined with individual and group therapy
Kelson, 2013	RCT	Army veterans living in poverty (homeless or nearly homeless)	N = 10; 10 male	25–60 y	Bipolar disorder or drug/alcohol addiction	Psychosis	20 session over 4 weeks, 30 min session of Infra Low Frequency Training; Sensors placements based on the Othmer Protocol Guide (2012) with T3–T4 and T4–P4 as starting protocols	All were on psychotropic medication.	Not receiving EEG Biofeedback
van der Kolk et al., 2016	RCT	Adults exposed to multiple traumas (childhood caregiver emotional abuse; sexual abuse; domestic violence) and treatment resistant PTSD	N = 52; 7 male	44.40 ± 13.15	Not reported	Unstable medical condition; Disability benefits; Suicide risk; Psychotic or bipolar disorder; TBI; Seizure disorder; SUD; DV; Changing ongoing treatment during study; GAF score <40.	24 bi-weekly sessions; 30 min session of High alpha training Starting reward frequency of 10–13 Hz and inhibit frequencies of 2–6 and 22–36 Hz. Adjustment of the reward band was based on subjects’ responses. Sensor placement: T4–P4	Required to continue all ongoing treatments (psychotherapeutic and pharmacological) with no changes to their treatment regimens. Reported medication: SSRIs, benzodiazepines, anxiolytics, Bupropion, SNRI tricyclic antidepressant, stimulants, antipsychotics.	Waitlist receiving psychotherapy and medication
Noohi et al., 2017	RCT	Adult patients (war/combat) with PTSD referred to hospital	N = 30; 30 male	25–60 y	Not reported	Psychotic and bipolar disorders; Serious limiting physical illness, such as cancer or kidney problems	25 sessions four times week; 30–40 min sessions of Alpha Theta training; Sensor placement: Pz	Not reported	Not reported
Bell et al., 2019	NRSI	Traumatized individuals (childhood abuse or neglect; domestic violence; first-responders; military veterans) with PTSD and at least 6 months post traumatic event	N = 23; 23 male	44 ± 16	MDD; Anxiety disorder; ADD, Fibromyalgia/Chronic Pain; Bipolar Disorder OCD; Dysthymic Disorder	Personality disorders (Axis II DSM-V); Suicidal ideation; Psychosis; TBI; Seizure disorder; significant unstable medical conditions; Pregnancy; Personality disorder.	15 bi-weekly sessions; 20 min session of Low Resolution Electromagnetic Tomography Analysis (LORETA) Z-score neurofeedback training targeting 3 brain networks (Default Mode Salience and Central Executive Network). Sensor placement: 19 channel corresponding to the 10–20 international system	Concurrent psychotherapy and medication 18 participants on psychotropic medication, not specified.	HRV Biofeedback
Nicholson, Ros, Jetly, et al., 2020	RCT double-blind	Traumatised individuals (military veterans; first responders; physical/sexual abuse or neglect) who had not responded to at least six months of trauma-focused psychotherapy	N = 36; 10 male	42.18 ± 11.63	MDD; Somatisation disorder Specific phobia	SUD; bipolar or psychotic disorders; in another primary trauma focused treatment; previous biofeedback treatment; suicidal ideation Unstable living conditions; DV; Noncompliance with 3 Tesla fMRI safety standards; Significant untreated medical illness; Pregnancy; Neurological or pervasive developmental disorders; TBI	20 weekly sessions; 20 min session of down-regulation of alpha rhythm (8–12hz); Sensor placement: Pz	Psychotropic medication: Antidepressants; SSRIs; SNRIs; tricyclics; atypical antipsychotics; sedatives; benzodiazepines; cyclopyrrolone and stimulants (methylphenidate).	Sham neurofeedback
Askovic et al., 2020	NRSI, retrospective	Adult refugees with chronic PTSD	N = 26; 17 male	44.85 ± 9.9	Anxiety; Depression	Current substance use disorder, severe neurological conditions, developmental delay, or need for urgent medical care.	27 (SD 12) sessions over 46 weeks (SD 32 weeks); 20 min session of individualised neurofeedback training protocols to target hyperarousal symptoms (anxiety, fear, insomnia), instability and problems with attention. Sensor placement: T4–P4 T3–T4 Cz–A2 or C4–A2 Fz-A1	Trauma counselling and medication. 13 participants on psychotropic medication, not specified.	Waitlist receiving trauma counselling
Leem et al., 2021	RCT	Traumatized individuals, traumatic events occurred more than 6 months before recruitment.	N = 22; 2 male	43.98 ± 16.35	Not reported	Severe mental disease (past or recent); when it is necessary to administer continuously a substance that is judged to have an effect on the induction of symptoms.	16 bi-weekly sessions; 50 min session of Alpha-theta training; Sensor placement: Pz	Allowed to continue on any drugs or nonpharmacological treatments that were previously being taken.	Waitlist receiving treatment as usual and life style intervention
du Bois et al., 2021	NRSI (3 arms)	Genocide survivors in Rwanda, high scores for PTSD in a previous study on transgenerational transmission of PTSD	N = 29; 29 female	53.72 ± 6.094	Not reported	Not reported	7 sessions; 25 min session of down-regulation of alpha rhythm (8–12hz); Sensor placement: Pz	Not reported	No treatment/Motor Imagery
Winkeler et al., 2022	RCT	Adults admitted to an inpatient treatment programme for eating disorders diagnosed with PTSD, with a history of childhood trauma	N = 36; 36 female	27.11 ± 5.28	Eating disorder; and frequent diagnosis of depression and emotionally unstable personality disorder	Treatment experience with NFB as well as epileptic seizures in patients' history	12 sessions; 30 min of Infra-low frequency training; Sensor placement: T4–P4, T3–T4, and T4–FP2	Regular inpatient treatment programme (individual psychotherapy 75 min per week, group psychotherapy 150 min per week + body awareness therapy, creative therapy, physical activity adapted to the physical condition, psychoeducation, nutritional counselling, and mealtime support as needed.)	Media Supported Relaxation