Predictors of violence in mental illness: the role of substance abuse and associated factors

This paper examines the hypothesis that rates of substance misuse and violence are similar between male patients admitted to secure psychiatric care and their age-matched male siblings. Forty-two consecutive male admissions and 18 of their male siblings were interviewed to determine rates of mental illness, violence and past substance use. Hair analysis was performed. Both groups showed high rates of substance misuse and offending. However, rates were higher among patients, suggesting that their substance misuse and violence cannot all be explained by familial factors alone. History of conduct disorder (CD), more common in patients, was associated with drug misuse and violent offending. This supports evidence from other sources, suggesting that CD can be an important intermediary step in the development of substance use disorders and violence in those who subsequently develop major mental illness. A history of antisocial behaviour should be considered when assessing risk in patients with a mental disorder and a substance misuse problem.