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 juveniledelinquents were investigated. The subjects had been examined In 'YoungLawbreakers': A study of 192 boys from an urban area, aged of 11-14 yearsin 1959-1963. They had committed crime against property, serious enoughfor prosecution if not being underaged. The control group included 95 boys,matched for age, family type, social group and area of dwelling. As adults theoriginal cohort was followed up sociologically and 199 of them alsopsychologically. Within a somatic-physiologic follow up, performed in 1989-91, the present study included 78 former juvenile delinquents and 47controls (mean age 43.5 years) of the psychologically examined subjects.Biological variables, behaviour symptoms during adolescence andpsychopathy related personality traits as adults were studied in relation tothe subjects' cumulated registered criminality. The juvenile delinquentswere classified into two groups: subjects registered for crime from 15 yearsof age and those who were not. Subjects from the control group, neverregistered for crime, were used as a normative group. All subjects weredistributed into 'low' and 'high' groups according to the median plateletmonoamine oxidase (MAO) activity and the mean of triiodothyronine (T3), ofthe control group, diagnosis of conduct disorder (CD) or not, and scores or noton the Psychopathy Check List (PCL). The presence of low platelet MAOactivity increased the relative risk for persistent criminality more than threetimes. Of juvenile delinquents with low platelet MAO activity and PCL scores70% persisted in crime in contrast to none of those with high platelet MAOactivity and no PCL score. No correlation was found between platelet MAOactivity and PCL scores. Increased levels of T3 were found to be associatedwith a more than three times increased risk for persistent criminality. Thepresence of symptoms of ADHD and CD were correlated to each other. CD wasfound to be the main contributor to persistent criminality. Risk indicators forpersistent criminality were low platelet MAO activity. Presence of PCLscores, high level of T3 and a diagnosis of CD. Configuration FrequencyAnalysis revealed one significant 'type' constituted by a high number of riskindicators, 'early' debut in crime and persistent criminality, and another'type' with no or a low number of risk indicators, 'late' debut in crime andno persistent criminality.Key words: Debut age, criminality, risk, monoamine oxidase,triiodothyronine, conduct disorder, psychopathy, juvenile delinquency,longitudinal research ISBN 91-628-1999-2 Stockholm 1996