Objective: To study the efficacy of divalproex in the treatment of PTSD. To study the plasma GABA levels before and after treatment with divalproex in PTSD.

Research Design: This is an 8-week randomized, double-blind, placebo-controlled treatment trial of divalproex.

Methodology: After signing an informed consent and meeting all inclusion/exclusion criteria, the patient is randomized to either divalproex or placebo for an 8-week duration. During the study a pharmacist maintains the randomization log and administers the placebo or divalproex (500 mg/capsule) in look-a-like tablets. Patients' symptoms, side effects and compliance are assessed bi-weekly. Based on symptomology and occurrence of side effects, the investigator increases the medication in 500 mg (one tablet) increments every four days, as tolerated, until a maximum therapeutic benefit is achieved, not to exceed 3000 mg/day (6 capsules). The dosing is twice daily, with the higher dose at bedtime. Compliance is assessed by bi-weekly pill count and blinded valproic acid levels at week 4 and week 8. Patients are given supportive clinical management during the clinic visits. An investigator is available by telephone 24 hrs a day in case of emergency. Patients may be seen more often if needed. Efficacy will be measured by the following assessment scales: MADRS (Montgomery-Asberg Depression Rating Scale), Ham-A (Hamilton Anxiety Scale), CGI-s (Clinical Global Impressions-Severity of Illness Scale), CGI-I (Clinical Global Impressions-Improvement Scale), GAF (Global Assessment of Functioning), CAPS (Clinician-Administered PTSD Scale), TOP-8 (Treatment Outcome PTSD Rating Scale), and DTS (Davidson Trauma Scale). Results of this study will be used to evaluate the efficacy of divalproex in the treatment of PTSD.

Significance: Divalproex has shown promise in treating PTSD in open label trials. This study is the next step in proving divalproex's efficacy in the treatment of PTSD.