Comparison of offenders with mental illness only and offenders with dual diagnoses.

OBJECTIVE: The study compared offenders who had severe mental illness only and offenders who had severe mental illness and substance abuse problems-dual diagnoses-to determine whether these groups differed. Offenders with dual diagnoses who were involved with the criminal justice system at different levels were compared to explore their profiles and experiences after release.
METHODS: Secondary data collected on offenders who had diagnoses of severe mental illness and of substance abuse in Massachusetts were used to examine sociodemographic, clinical characteristics, and criminal justice characteristics, service needs, and community reentry experiences in the first three months postrelease of 265 offenders with major mental illness and 436 with dual diagnoses.
RESULTS: Offenders with dual diagnoses were more likely to be female and to have a history of being on probation and of using mental health services. On release from correctional custody, they had more immediate service needs than offenders with mental illness alone, including a need for housing and sex offender treatment, and they were more likely to require an assessment for dangerousness. They were also more likely to return to correctional custody.
CONCLUSIONS: The data do not suggest that offenders with dual diagnoses have a distinct clinical background, but rather that substance abuse is an important feature that affects their real or perceived level of functioning, engagement with the criminal justice system, and dependence on social service institutions in the community.