Joint occurrence of depression and aggression in children and adults with mental retardation.

The relationship between aggression and depression was evaluated for 528 adults, adolescents and children, who were rated on either the adult or child versions of the Reiss instruments for dual diagnosis (Reiss 1988; Reiss & Valenti-Hein 1990). Criterion levels of depression were evident in about four times as many aggressive as nonaggressive subjects. Anger was significantly associated with both aggression and depression. Although anger may play a mediational role in the correlation between aggression and depression, in this study there was a significant correlation even after the effects of anger were held constant. The findings provide an initial step toward improving diagnostic specificity when evaluating aggressive behaviour in people with mental retardation.