Juvenile and adult criminality : relationships to platelet MAO activity, triiodothyronine, ADHD, conduct disorder and psychopathy

Abstract: Indicators for persistent risk criminality in a group of grown up juvenile delinquents were investigated. The subjects had been examined In 'Young Lawbreakers': a study of 192 boys from an urban area, aged 11-14 years in 1959-1963. They had committed crime against property, serious enough for prosecution if not being underaged. The control group included 95 boys, matched for age, family type, social group and area of dwelling. As adults the original cohort was followed up sociologically and 199 of them also psychologically. Within a somatic-physiologic follow up, performed in 1989-91, the present study included 78 former juvenile delinquents and 47 controls (mean age 43.5 years) of the psychologically examined subjects. Biological variables, behaviour symptoms during adolescence and psychopathy related personality traits as adults were studied in relation to the subjects' cumulated registered criminality. The juvenile delinquents were classified into two groups: subjects registered for crime from 15 years of age and those who were not. Subjects from the control group, never registered for crime, were used as a normative group. All subjects were distributed into 'low' and 'high' groups according to the median platelet monoamine oxidase (MAO) activity and the mean of triiodothyronine (T3), of the control group, diagnosis of conduct disorder (CD) or not, and scores or not on the Psychopathy Check List (PCL). The presence of low platelet MAO activity increased the relative risk for persistent criminality more than three times. Of juvenile delinquents with low platelet MAO activity and PCL scores 70% persisted in crime in contrast to none of those with high platelet MAO activity and no PCL score. No correlation was found between platelet MAO activity and PCL scores. Increased levels of T3 were found to be associated with a more than three times increased risk for persistent criminality. The presence of symptoms of ADHD and CD were correlated to each other. CD was found to be the main contributor to persistent criminality. Risk indicators for persistent criminality were low platelet MAO activity. Presence of PCL scores, high level of T3 and a diagnosis of CD. Configuration Frequency Analysis revealed one significant 'type' constituted by a high number of risk indicators, 'early' debut in crime and persistent criminality, and another 'type' with no or a low number of risk indicators, 'late' debut in crime and no persistent criminality.