Criminality and psychopathy as related to thyroid activity in former juvenile delinquents.

Levels of triiodothyronine (T3) and thyroid-stimulating hormone (TSH), psychopathy-related personality traits and criminality from the age of 15 years onward were examined in 70 former juvenile delinquents and 35 control subjects aged 38-46 years. T3 levels were significantly associated with criminality but not with psychopathy-related personality traits. TSH levels were not related to any of these variables. Juvenile delinquents who displayed persistent criminal behaviour were found to have higher mean T3 levels than juvenile delinquents who did not display criminality in adulthood and non-criminal controls. Former juvenile delinquents with T3 levels above the mean level found in the controls were registered for criminality 3.8 times more often than juvenile delinquents with T3 levels below the mean level found in the control group. The results are discussed in terms of elevated T3 levels representing a compensatory or stress phenomenon for low social adaptive ability of individuals who display persistent criminal behaviour.