U.S. military veterans who are being treated for schizophrenia are much less likely to drink any alcohol than the general population. However, they are equally likely to misuse alcohol. And when they do misuse alcohol, it leads to worsening of their symptoms, according to a new study led by Dr. Alexander Young, a psychiatry professor at UCLA.

Alcohol and drug use disorders are believed to have substantial negative effects on outcomes in people with schizophrenia. However, it has not been possible to know the extent of this problem, because diagnoses and details regarding substance use are typically not documented in people’s medical records, previous research shows.

Prior studies of veterans with serious mental illness have found that heavy drinking prevents them from sticking to prescribed medication regimens. Efforts to reduce alcohol misuse and better ensure that veterans with schizophrenia take their medications would improve outcomes for them and could reduce the incidence of hospitalization.

Researchers randomly selected 801 veterans undergoing treatment for schizophrenia at Veterans Health Administration medical centers in California, New York, Louisiana and Texas. Trained assessors conducted confidential interviews to collect information about their psychiatric symptoms, how well they followed their prescription regimens, alcohol and illicit drug use, quality of life, and use of treatment services.

At these clinics, only 23 percent of those interviewed said that they drank any alcohol in the previous 30 days. Fifteen percent reported some use and 7 percent reported drinking alcohol to intoxication, or “misuse.” In contrast, 56 percent of the general population report drinking in the past month, according to the National Institute on Alcohol Abuse and Alcoholism.

The veterans in the study who misused alcohol were less likely to take their medications as prescribed, more likely to use other drugs and had worse quality of life. Both alcohol users and misusers, compared with those who didn’t drink at all, reported less use of general medical, mental health and housing services. Less use of services correlates with worse outcomes.

The findings indicate there is no safe level of alcohol use for people with schizophrenia, suggesting that clinicians should ask patients with schizophrenia about alcohol use or misuse and advise them about risks.

The study’s authors are Young and Amy Cohen, both in the department of psychiatry and biobehavioral sciences at UCLA; and Eric Pedersen and Wenjing Huang of the RAND Corporation.

The study was published in the journal Psychological Services.