Post-traumatic stress and insanity.

Clinicians and lawyers have expressed fears over the past decade that many criminal defendants might improperly claim that post-traumatic stress disorder (PTSD) rendered them insane and not accountable for their behavior. But the largest study of the insanity defense to date indicates that insanity pleas rarely involve people diagnosed with PTSD.

Paul S. Appelbaum, a psychiatrist at the University of Massachusetts Medical Center in Worcester, and his co-workers collected data on all insanity pleas entered in 49 counties in eight states between 1980 and 1986. States included California, New York, Ohio, and Georgia. PTSD, which encompasses a range of symptoms caused by exposure to severe stress, entered the manual of psychiatric diagnoses in 1980.

Of 8,163 defendants pleading not guilty by reason of insanity, only 28 had a diagnosis of PTSD, the researchers assert in the February AMERICAN JOURNAL OF PSYCHIATRY Defendants with and without PTSD had been arrested and hospitalized for psychiatric conditions about the same number of times, they note. Those with PTSD did not commit an excess of violent crimes, and they were not more successful with insanity pleas than defendants citing other psychiatric disorders.

It remains unclear how often defendants employ PTSD in other ways, the researchers note, such as using it to argue for "diminished capacity" or as a defense in civil court cases.