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

Levels of triiodothyronine (T-3) 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. T-3 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 T-3 levels than juvenile delinquents who did not display criminality in adulthood and non-criminal controls. Former juvenile delinquents with T-3 levels above the mean level found in the controls were registered for criminality 3.8 times more often than juvenile delinquents with T-3 levels below the mean level found in the control group. The results are discussed in terms of elevated T-3 levels representing a compensatory or stress phenomenon for low social adaptive ability of individuals who display persistent criminal behaviour.