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The findings highlight the need to educate this population about the risks associated with substance use and closely monitor patients’ substance use.
Substance use disorders are known to be common in patients with schizotypal disorder, but whether these disorders might be associated with conversion to schizophrenia was previously unclear, according to lead author Carsten Hjorthøj, Ph.D., M.Sc., of Copenhagen University Hospital and colleagues.
Hjorthøj and colleagues relied on data contained in Danish registries to identify a cohort of 2,539 people born in Denmark who had been diagnosed with schizotypal disorder. The researchers then tracked the patients from schizotypal diagnosis until diagnosis of schizophrenia, death, migration, or August 10, 2014.
According to the researchers, 16.3% of those with schizotypal disorder had experienced conversion to schizophrenia after two years. After 20 years, 30.6% of individuals without any substance use disorder had experienced conversion to schizophrenia. For those with cannabis use disorder, the 20-year conversion rate was 58.2%.
Further analysis revealed that cannabis use disorders, amphetamine use disorders, and opioid use disorders were associated with conversion to schizophrenia. “These associations were not explained by concurrent use of antipsychotics, functional level before incident schizotypal disorder, or parental history of mental disorders,” Hjorthøj and colleagues wrote.
Though the findings suggest substance use disorders—in particular cannabis, amphetamines, and opioids—may be associated with conversion from schizotypal disorder to schizophrenia, the authors noted that “conversion rates are high even in those without substance use disorders, indicating a need for universal and substance-targeted prevention in individuals with schizotypal disorder.”
For related information, see the Psychiatric News article “Early End to Substance Use Linked to Better Outcome in First-Episode Psychosis.”
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