Seasonality of bipolar disorders in a forensic setting.

The authors studied 180 men who were found not guilty by reason of insanity (NGBRI) and committed to a forensic hospital for treatment. The 57 men diagnosed as bipolar disorder committed the crime for which they were found NGBRI (and which was, therefore, the result of mental illness) significantly more frequently during the 6 months August through January. The crimes committed by those in the bipolar group who were 31 years or older showed even seasonality. The crimes committed by the 123 men found NGBRI but not diagnosed as bipolar showed no seasonality. During the past 5 years on the forensic unit, the seclusion time, which was due primarily to manic behavior, was significantly higher during the 4 months December through March. These observations establish a seasonality of mania that appears age-related.