Effects of the atypical antipsychotic risperidone on hostility and aggression in schizophrenia: a meta-analysis of controlled trials.

Atypical antipsychotics have been hypothesized to be more effective than classical antipsychotics in the treatment of hostility and aggression, due to their characteristic pharmacological profile, involving serotonergic as well as dopaminergic systems. In the present quantitative review the published evidence regarding the effects of risperidone on hostility and aggression in schizophrenia is evaluated. Meta-analysis of seven controlled trials revealed significant differences between risperidone and classical antipsychotics and between risperidone and placebo, although the effect size was small. Additional analyses in which only methodological rigorous studies were included showed highly significant differences (risperidone versus classical antipsychotics) and the effect size approached the 'medium' range. We conclude that risperidone is superior to classical antipsychotics and placebo in the treatment of hostility and aggression in schizophrenia. Neuropharmacological mechanisms that might account for this effect are discussed, and directions for future research are outlined.