Substance abuse may increase risk for schizophrenia

Substance abuse, particularly cannabis and alcohol, were associated with increased risk for schizophrenia, according to data presented at the International Early Psychosis Association meeting.

“Several studies have tested whether use of substances can cause schizophrenia. However, due to methodological limitations in the existing literature, uncertainties remain,” Stine Mai Nielsen, MSc, of Copenhagen University Hospital, Denmark, and colleagues wrote.

To assess associations between substance abuse and risk for schizophrenia, researchers conducted a nationwide prospective register-based cohort study of all residents born in Denmark from 1955 to 1999 (n = 3,133,968).

Overall, 204,505 participants were diagnosed with substance abuse and 21,305 were diagnosed with schizophrenia.

Substance abuse increased risk for schizophrenia (HR = 6.04; 95% CI, 5.84-6.26), with strongest associations for cannabis (HR = 5.2; 95% CI, 4.86-5.57) and alcohol (HR = 3.38; 95% CI, 3.24-3.53) use.

Researchers found that risk was significant 10 to 15 years prior to substance abuse diagnosis.

“Our results illustrate a robust association between almost any type of substance abuse and an increased risk of developing schizophrenia later in life,” the researchers concluded. – by Amanda Oldt

Reference:

Nielsen SM, et al. Abuse of alcohol and illicit substances and risk of developing schizophrenia: A nationwide population based register study. Presented at: International Early Psychosis Association Annual Meeting; Oct. 20-22, 2016; Milan.

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