Consumers of state supported mental health services often may have additional diagnoses. For people with mental illness, dual diagnosis is most likely to involve substance abuse. National prevalence data suggests that about 27% of individuals with chronic serious mental illness abuse substances and that about 15% of individuals with serious mental illness also abuse substances. The experience of Alaskan providers suggests the co-occurrence of serious substance abuse is much higher.
Alaskan data is available from two principle sources. Medicaid files indicate that 8% of mental health consumers also have chronic alcoholism with psychoses. A 1997 Bristol Observatory report puts the number of community mental health center admissions also admitted to substance abuse programs at 21%, which accords with national dual diagnosis estimates. In addition, 44% of mental health consumers receiving Medicaid benefits are also identified as mental health consumers receiving services for developmental disabilities.