A comparison of the patterns of drug use among patients with and without severe mental illness.

We compared the patterns of substance use among patients with severe mental illness (SMI) served by three community treatment teams, substance users with non-severe mental illness (NSMI), and substance abusers without mental illness (no mental illness: NMI). There were highly significant differences in substance use patterns among the groups: among patients with SMI, the order of drug preference was alcohol, cocaine, cannabis, and then heroin; in the NMI group, it was cocaine, alcohol, heroin, and then cannabis; while in the NSMI group, it was alcohol, cocaine, heroin, and then cannabis. The data suggest that the choice of drugs by individuals with SMI may be determined by factors related to their illness, in addition to the price and availability of the particular drug.