Drug and alcohol use

How is drug and alcohol use related to schizophrenia? 

Drug and alcohol use, abuse or dependence are concerns due to the association with high rates of suicide, HIV, homelessness, aggression and incarceration. Moreover, comorbid substance use places additional burden on patients, families, psychiatric services, and government resources due to high rates of treatment non-adherence and relapse.

What is the evidence for comorbid drug and alcohol use?

Moderate quality evidence shows the lifetime prevalence of any illicit drug misuse, abuse or dependence in people with schizophrenia ranges between 17% for those in rehabilitation and long-term settings, to 70% in community health settings.

The lifetime prevalence rates of alcohol misuse, abuse or dependence ranges between 29% for those in rehabilitation and long-term settings to 75% in community health settings. Prevalence of alcohol use is higher in studies using the Diagnostic and Statistical Manual of Mental Disorders (DSM) III-revised diagnostic criteria compared to studies using DSM-IV, or the International Classification of Diseases (ICD) 9 or 10. Prevalence is also higher in samples aged 30 to 40 years and in studies published between 1990 and 1995.

The lifetime prevalence of cannabis use disorders in people with schizophrenia is around 27%, with current prevalence around 16%. The prevalence of any cannabis use in first episode psychosis patients is around 33-38%, and around 53% for those at ultra high risk for psychosis. Prevalence is higher in males and in people under 30 years of age. The initiation of cannabis use is usually around 6-7 years prior to onset of psychosis, and continuation of cannabis use declines after treatment.

The rate of stimulant use disorders in people with psychosis is around 9%. Studies including patients with affective psychosis as well as patients with schizophrenia, studies of inpatients, cannabis users, and studies from USA and Australia report the highest rates of stimulant use.

Any lifetime substance use, particularly cannabis, is associated with an earlier age of onset of psychosis.

April 2019

Last updated at: 4:11 am, 18th April 2019
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