Aggressive behaviour in patients with schizophrenia is associated with catechol-O-methyltransferase genotype

Background Evidence exists for an association between aggression and schizo phrenia. Although the aetiology of aggression is multifactorial, three stud ies have reported associations between polymorphisms of the catechol-O-meth yltransferase (COMT) gene and aggression in schizophrenia. Aims To replicate these findings in a larger sample using the Overt Aggress ion Scale (OAS). Method A sample of 180 people with DSM-IV schizophrenia were rated for aggr ession using the OAS. Kruskal-Wallis and contingency table analyses were ap plied to the OAS results. Results The high-activity homozygotes showed significantly higher scores of aggression, whereas the heterozygotes showed significantly lower scores. T he odds ratio for aggression for the high-activity homozygotes was 2.07 (95 % CI=1.03-4.15), whereas that for the heterozygotes was 0.54 (95% CI=0.30-1 .00). Conclusions The high-activity COMT homozygote confers a higher risk of reco rded aggression in schizophrenia. Heterozygotes had a significantly lower r isk, which may represent an example of heterosis/heterozygote advantage.