Platelet monoamine oxidase B activity did not predict destructive personality traits or violent recidivism: a prospective study in male forensic psychiatric examinees.

AIMS: This prospective study was designed to replicate previous findings of an association between the platelet monoamine oxidase B (MAO-B) activity and factors of relevance for criminal behaviour in a well-documented clinical study population.

METHODS

Subjects (n = 77, aged 17-76 years, median 30 years) were recruited among consecutive perpetrators of severe interpersonal violent and/or sexual crimes referred to forensic psychiatric investigation. Participants were extensively investigated by structured psychiatric, psychological and social workups, including state-of-the-art rating instruments and official records, and with laboratory tests including venous blood sampling for determination of MAO-B activity. A subset of 36 individuals had lumbar punctures to measure cerebrospinal fluid concentrations of monoamine neurotransmitter metabolites.

RESULTS

Platelet MAO-B activity did not show any significant correlation with assessments of childhood behavioural disorders, substance abuse, or psychosocial adversity, nor with any crime-related factors, such as scores on the Life History of Aggression Scale, the Psychopathy Checklist or recidivistic violent crime. No significant correlation was found between MAO-B and any of the monoamine metabolites. Analyses in subgroups of smokers/non-smokers did not change this overall result.

CONCLUSIONS

The findings of the present study did not support the use of MAO-B as a biological marker for aggression-related personality traits or as a predictor for violent recidivism among violent offenders.