The purpose of this study is to evaluate the short-term efficacy and safety of levetiracetam in post-traumatic stress disorder (PTSD) and to evaluate continuation effects of levetiracetam in preventing PTSD relapse. The hypothesis is that levetiracetam will be safe and effective in preventing relapse of PTSD.

This is an investigator-initiated, single site study, consisting of two phases: 8 weeks of open label treatment with levetiracetam (500-2000 mg/day) in patients with PTSD, and in those who demonstrate at least minimal improvement, 12 weeks of randomized, double-blind treatment with either levetiracetam or matching placebo.

Inclusion Criteria:

• ages 18-65
• primary diagnosis of PTSD based on DSM-IV criteria and assessed by the MINI International Neuropsychiatric Interview (MINI)
• Davidson Trauma Scale (DTS) score of at least 40 on screening
• ability to provide written informed consent

Exclusion Criteria:

• any primary DSM-IV Axis I disorder other than PTSD
• substance abuse during the last 6 months
• a clinically unstable medical condition or clinically significant laboratory abnormalities
• suicide risk or serious suicide attempt during the last year
• concurrent use of psychotropic medications including benzodiazepines, barbiturates, antiepileptic drugs, antidepressants, buspirone, dietary supplements or herbal or homeopathic remedies with psychotropic effects
• recent (within the last 3 months) initiation of cognitive behavioral therapy
• failure of a previous trial of levetiracetam at 2000 mg/day
• pregnancy or lactation
• women of childbearing potential who are unwilling to practice an acceptable method of contraception