While patients with schizophrenia are more likely to be victims rather than perpetrators of aggressive behaviour, prior research has shown increased rates of aggressive behaviours in these patients that appear very early in the course of illness. We aimed to assess aggression in antipsychotic-naive first-episode schizophrenia patients, their healthy siblings, and controls; and to investigate correlates of aggression in the patients group.
Patients (N = 55), siblings (N = 55) and healthy controls (N = 71) were evaluated on Buss and Perry Aggression Questionnaire (AQ), Life History of Aggression (LHA), Barratt Impulsiveness Scale, and Levenson Self-Report Psychopathy Scale. Age, gender and substance use were regarded as covariates, and differences between the three groups were evaluated using analysis of covariance. Hierarchical regression was performed to determine which variables were associated with aggression level in the patients group.
The Tukey multiple comparison test showed that both patients (p < .001) and siblings (p = .023) scored higher on the LHA Aggression than controls. Siblings scored higher than controls (p = .010) for the Anger subscale of the AQ. Patients scored significantly higher than controls in the three impulsiveness dimensions; whereas siblings scored higher than controls in the motor (p = .023) and non-planning (p = .004) dimensions. Multivariate analyses showed that, after controlling for confounders, only attentional impulsiveness (β = .446, p = .0244) and psychopathy traits (β = .359, p = .010) helped predict AQ total scores among patients.
Aggression and some of its risk factors including impulsiveness are likely to be trait variables that might provide important vulnerability markers for people at heightened risk of developing psychosis.