Effect of COMT genotype on aggressive behaviour in a community cohort of schizophrenic patients.

Although the etiology of aggression is multifactorial, many studies have associated the Val158Met polymorphism of the COMT with aggression in schizophrenia. This study tests the hypothesis that Met/Met patients display more episodes of aggression and violent behaviour than Val/Val patients in a 6 year follow-up cohort of subjects with schizophrenia in contact with the South-Verona Community-based Mental Health Service. Out of the 141 subjects with an ICD-10 SCAN-confirmed diagnosis of schizophrenia, 115 completed both baseline and follow-up assessments (81.6% of the baseline cohort). Of these, 80 subjects (70%) were genotyped and rated for aggression using the Overt Aggression Scale. Met/Met homozygous patients had higher aggressive behaviour compared to Val/Val homozygous subjects. Antipsychotic dosage, alcohol and drug abuse were taken into account as confounders. The Met/Met genotype of COMT may have an effect on aggressive behaviour in schizophrenia because norepinephrine is less effectively inactivated.