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Drug and alcohol misuse

How is drug and alcohol misuse related to schizophrenia? 

Drug and alcohol misuse, abuse or dependence are concerns for people with schizophrenia due to the association with poorer clinical and social outcomes, including 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 misuse?

Moderate quality evidence suggests the lifetime prevalence rates of any illicit drug misuse, abuse or dependence range from 17% in rehabilitation and long-term settings, to 70% in community health settings. Any lifetime substance use, particularly cannabis, is associated with an earlier age of onset of psychosis.

Moderate quality evidence suggests prevalence of any cannabis use in first episode psychosis patients is around 33-38%, and moderate to low quality evidence suggests lifetime prevalence of cannabis use disorders in people with schizophrenia is around 27%, with current prevalence around 16%. Prevalence is higher in males compared to females, in people under 30 years of age compared with people over 30 years of age, and in people with first episode schizophrenia compared with people with chronic schizophrenia. The initiation of cannabis use is around 6-7 years prior to onset of psychosis, and continuation of cannabis use declines after treatment.

Moderate quality evidence suggests the rate of stimulant use disorders in people with psychosis is around 9%. Studies including patients with affective psychosis, inpatients, cannabis users, and those from USA and Australia report the highest rates of stimulant use.

Moderate quality evidence suggests lifetime prevalence rates of alcohol misuse, abuse or dependence in people with schizophrenia range from 29% in rehabilitation and long-term settings to 75% in community health settings. Prevalence is higher in studies using the Diagnostic and Statistical Manual of Mental Disorders (DSM) III-revised diagnostic criteria compared to studies using DSM-IV, International Classification of Diseases (ICD) 9 or 10. Prevalence is higher in samples aged 30 to 40 years compared with other age groups, and in studies published between 1990 and 1995 compared with earlier publications.

Also see the Course and Outcomes drug and alcohol use topic, the Risk Factor substance use topic, the Psychosocial Treatments for dual diagnosis topic, and the Pharmaceutical Treatments for dual diagnosis topic.


March 2016

Page last updated: 5:12  4 February 2019

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