Incarceration associated with homelessness, mental disorder, and co-occurring substance abuse.

Objective: This study assessed relationships between homelessness, mental disorder, and incarceration.

Methods: Using archival databases that included all 12,934 individuals who entered the San Francisco County Jail system during the first six months of 2000, the authors assessed clinical and behavioral characteristics associated with homelessness and incarceration.

Results: In 16 percent of the episodes of incarceration, the inmates were homeless, and in 18 percent of the episodes, the inmates had a diagnosis of a mental disorder; 30 percent of the inmates who were homeless had a diagnosis of a mental disorder during one or more episodes. Seventy-eight percent of the homeless inmates with a severe mental disorder had co-occurring substance-related disorders. Inmates with dual diagnoses were more likely to be homeless and to be charged with violent crimes than other inmates. Multiple regression analyses showed that inmates who were homeless and had co-occurring severe mental disorders and substance-related disorders were held in jail longer than other inmates who had been charged with similar crimes.

Conclusions: People who were homeless and who were identified as having mental disorders, although representing only a small proportion of the total population, accounted for a substantial proportion of persons who were incarcerated in the criminal justice system in this study's urban setting. The increased duration of incarceration associated with homelessness and co-occurring severe mental disorders and substance-related disorders suggests that jails are de facto assuming responsibility for a population whose needs span multiple service delivery systems.