Oral administration of Placebo, 90 minutes prior to a brief memory reactivation session, performed by a trained nurse, once a week for six consecutive weeks.

Difference on score on the Post Traumatic Stress Disorder Checklist for DSM-5 (PCL-5) between inclusion and 3 months after the beginning of the treatment. PCL-5 is a 20-item self-report measure of the DSM-5 symptoms of PTSD used as a continuous measure. A decrease of 10 points on the PCL is usually considered as a clinically significant improvement. It has been used worldwide and among adolescents (Wang, 2015; Cao, 2017) Scores consist of a total symptom severity score (from 0 to 80)

Consistent with the likert scale:

0 = Not at all

1. = A little bit
2. = Moderately
3. = Quite a bit
4. = Extremely

Higher scores mean a worse outcome.

Difference on score on the Post Traumatic Stress Disorder Checklist for DSM-5 (PCL-5) between inclusion and 6 months after the beginning of the treatment. PCL-5 is a 20-item self-report measure of the DSM-5 symptoms of PTSD used as a continuous measure. A decrease of 10 points on the PCL is usually considered as a clinically significant improvement. It has been used worldwide and among adolescents (Wang, 2015; Cao, 2017) Scores consist of a total symptom severity score (from 0 to 80)

Consistent with the likert scale:

0 = Not at all

1. = A little bit
2. = Moderately
3. = Quite a bit
4. = Extremely

Higher scores mean a worse outcome.

Difference on score on the Post Traumatic Stress Disorder Checklist for DSM-5 (PCL-5) between inclusion and 12 months after the beginning of the treatment. PCL-5 is a 20-item self-report measure of the DSM-5 symptoms of PTSD used as a continuous measure. A decrease of 10 points on the PCL is usually considered as a clinically significant improvement. It has been used worldwide and among adolescents (Wang, 2015; Cao, 2017) Scores consist of a total symptom severity score (from 0 to 80)

Consistent with the likert scale:

0 = Not at all

1. = A little bit
2. = Moderately
3. = Quite a bit
4. = Extremely Higher scores mean a worse outcome.

Difference in functional impairment score of CPC-DSM5 at inclusion visit, before each dispensation of treatment (once per week for 6 weeks), one week after the end of treatment and 3, 6 and 12 months after the beginning of treatment. Functional impairment score will be assessed using CHILD PTSD CHECKLIST PARENT questionnaire. CPC is a self-questionnaire of 12 items. The total severity score ranges from 0 to 80 and is calculated by summing the ratings of the first 20 items. The CPSS-5-I also yields subscale scores for intrusion (Items 1-5), avoidance (Items 6-7), changes in cognition and mood (Items 8-14), and increased arousal and reactivity (Items 15-20).

The interviewer rates the seven impairment items on a scale of 0 (not at all) to 4 (6 or more times a week/almost always), resulting in an impairment score that ranges from 0 to 28. The total impairment score does not contribute to the overall severity score.

Difference in Categorical diagnosis of PTSD using SCID-5 questionnaire at inclusion visit, before each dispensation of treatment (once per week for 6 weeks), one week after the end of treatment and 3, 6 and 12 months after the beginning of treatment. SCID-5 is for Structured Clinical Interview for DSM-5 is a semi-structured interview guide for making the major DSM-5 diagnoses used for the diagnosis of PTSD and depression.

Difference in Child Depression Inventory (CDI) score between inclusion visit and one week after the end of treatment, 6 months and 12 months after the beginning of treatment. There are 27 items quantifying symptoms such as depressed mood, hedonic capacity, vegetative functions, self-evaluation, and interpersonal behaviors. Each item consists of three statements graded in order of increasing severity from 0 to 2; children and adolescents select the one that characterized their symptoms best during the past 2 weeks. The item scores are combined into a total depression score, which ranges from 0 to 54. A higher CDI score means a higher depressive state.

Difference in Adolescent Dissociative Experience (DES-A) score at inclusion visit, one week after the end of treatment, 6 and 12 months after the beginning of treatment. DES-A is a 28-items selfquestionnaire. Each item reaches to 0 (never happening) to 10 (always happening)

Scores for Behavioral and Somatic Disorders and for School/social functioning using Youth Self report (CBCL/YSR, parents/children) at inclusion visit , one week after the end of treatment, 6 and 12 months after the beginning of treatment. The YSR is a 112-item self-report designed for children and adolescents (ages 11-17) and largely used worldwide. It assesses behavioral competency and behavioral problems and parallels the Child Behavior Checklist (CBCL). The questionnaire provides scores for the following syndrome scales: anxious/depressed, withdrawn/depressed, somatic complains, social problems, thought problems, rule-breaking behavior, and aggressive behavior. The questionnaire provides scores for DSM-oriented scales.

The YSR consists of 112 questions, scored on a three-point Likert scale (0=absent,

1= occurs sometimes, 2=occurs often) Higher scores mean a worse outcome.

Difference in acute suicidal risk using Mini Kid questionnaire at inclusion visit , one week after the end of treatment, 6 and 12 months after the beginning of treatment. The Mini-International Neuropsychiatric Interview for Children and Adolescents (MINI Kid) is a short, structured diagnostic interview for DSM-IV and ICD-10 psychiatric disorders in children and adolescents. Only part C will be used to assess diagnosis of acute suicidal risk. Scores reaches from 0 to 10 Higher scores mean a worse outcome.

Evaluation of the tolerance to treatment at each dispensation of treatment (once per week for 6 weeks) by the research nurse: Clinical evaluation