Individuals with co-occurring disorders have higher levels of psychological distress and poorer psychosocial functioning, as compared with individuals with substance dependence only. Studies identified substance abuse as a risk factor, which increases the likelihood that an individual with mental disorders may become violent.

To examine the gender differences in drug-related problems and predictors of recidivism among a sample of 1,444 offenders with co-morbid drug abuse and mental disorders participating in California's Proposition 36.

Characteristics and problem severity in multiple key life areas were assessed at intake using Addiction Severity Index, and drug treatment participation, mental health diagnoses and arrests were based on official records.

Women demonstrated greater problem severity than men in family relationships, health, psychological health, and sexual and physical abuse history. Men on the other hand had greater criminal history, high rates of attention disorder, and psychotic disorder. Logistic regression analyses showing that for the combined sample, male, young age, cocaine use (relative to methamphetamine), drug abuse severity, methadone treatment, arrest history and fewer prior treatment history were associated with higher recidivism at 12-month follow-up; lower education, cocaine use, and arrest history were related to women's recidivism, while young age, outpatient treatment, and arrest history were predictors of men's recidivism.

Although the specific type of mental disorder did not seem to be predictive of recidivism, the high rates of mental health disorder and arrest of this population is problematic. Intervention strategies taking into consideration gender-specific problems and needs can improve outcomes for both.