OBJECTIVE: This was a 12-week randomized, placebo-controlled trial to assess the 
efficacy of quetiapine monotherapy in the treatment of posttraumatic stress 
disorder (PTSD).
METHOD: Eighty patients were randomly assigned to treatment with either 
quetiapine or placebo. The primary outcome measure was the 
Clinician-Administered PTSD Scale (CAPS). Secondary efficacy measures included 
the CAPS subscales, the Davidson Trauma Scale, the Positive and Negative 
Syndrome Scale (PANSS), the Clinical Global Impressions (CGI) scales for 
severity of Illness and improvement, the Hamilton Depression Rating Scale 
(HAM-D), and the Hamilton Anxiety Rating Scale (HAM-A). Safety measurements 
included adverse events, vital signs, the Abnormal Involuntary Movement Scale, 
the Barnes Akathisia Scale, the Simpson-Angus Scale, and the Arizona Sexual 
Experiences Scale.
RESULTS: After a 1-week placebo run-in, quetiapine was started at a daily dosage 
of 25 mg and increased to a maximum of 800 mg; the average was 258 mg (range, 
50-800 mg). Reductions in CAPS total, re-experiencing, and hyperarousal scores 
were significantly greater for the quetiapine group than for the placebo group. 
Greater improvements were also observed for quetiapine in scores on the Davidson 
Trauma Scale, CGI severity and improvement ratings, PANSS positive symptom and 
general psychopathology subscales, HAM-A, and HAM-D than for placebo. Adverse 
events were generally mild and expected based on prior studies of quetiapine in 
this and other patient population. There were no differences in safety measures 
between groups.
CONCLUSION: Quetiapine monotherapy was efficacious in the treatment of PTSD. 
These findings suggest quetiapine as a single agent is effective in treating 
military PTSD.