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

<bold>Background: </bold>Evidence exists for an association between aggression and schizophrenia. Although the aetiology of aggression is multifactorial, three studies have reported associations between polymorphisms of the catechol-O-methyltransferase (COMT) gene and aggression in schizophrenia.<bold>Aims: </bold>To replicate these findings in a larger sample using the Overt Aggression Scale (OAS).<bold>Method: </bold>A sample of 180 people with DSM-IV schizophrenia were rated for aggression using the OAS. Kruskal-Wallis and contingency table analyses were applied to the OAS results.<bold>Results: </bold>The high-activity homozygotes showed significantly higher scores of aggression, whereas the heterozygotes showed significantly lower scores. The odds ratio for aggression for the high-activity homozygotes was 2.07 (95% Cl=1.03-4.15), whereas that for the heterozygotes was 0.54 (95% Cl=0.30-1.00). CONCLUSIONS; The high-activity COMT homozygote confers a higher risk of recorded aggression in schizophrenia. Heterozygotes had a significantly lower risk, which may represent an example of heterosis/heterozygote advantage. [ABSTRACT FROM AUTHOR]