Substance-Induced Psychosis Associated With Increased Risk of Schizophrenia, Meta-Analysis Finds

People who experience psychosis following the use of cannabis, hallucinogens, or amphetamines (known as substance-induced psychosis) may be at a greater risk of developing schizophrenia, according to a meta-analysis in Schizophrenia Bulletin. This risk was found to be only slightly less than that observed for patients who presented with other brief psychotic disorders.

“These findings have important implications for mental health care and services. Substance-induced psychoses are common reasons for seeking mental health care,” wrote Grant Sara, M.B., of the University of Sydney and colleagues. “Yet despite this, people with substance-induced psychoses are often excluded from early psychosis services or assertive mental health care due to a perception that these are benign or self-limiting conditions.”

Sara and colleagues searched MEDLINE, PsychINFO, and Embase for peer-reviewed, English-language studies published between 1980 and 2018 that looked at how often patients with substance-induced psychoses were later diagnosed with schizophrenia. They compared this group with those who had an initial diagnosis of “brief psychosis,” “atypical psychosis,” “schizophreniform psychosis,” or “psychosis not otherwise specified” who were later diagnosed with schizophrenia.

The researchers identified 50 studies, which included more than 40,500 people. Of these studies, 25 looked at later diagnosis of schizophrenia among people who had substance-induced psychosis (following use of cannabis, hallucinogens, amphetamines, alcohol, sedatives, or opioids).

Overall 25% of people with substance-induced psychosis were later diagnosed with schizophrenia, compared with 36% of people who first presented with brief, atypical, and not otherwise specified psychoses. Among the 25 studies that looked at substance use-induced psychosis, transition to schizophrenia was highest (34%) for cannabis-induced psychoses.

“The importance of assertive intervention in this group is underlined by evidence that integrated care, which addresses substance use disorders and psychosis, can have a significant impact on course,” the researchers wrote. “Such care can double the likelihood of remission in early psychosis; reduce the risk for hospital re-admission; and lead to better symptomatic, drug use, and functional outcomes at 10-year follow-up.”

For more information, see the Psychiatric News article “Substance-Induced Psychosis Associated With Later Schizophrenia, Bipolar Disorder.”

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