Psychedelic use linked to an increased risk of schizophrenia, research shows

Individuals who attend emergency rooms involving the use of hallucinogens are at high risk of developing schizophrenia, according to a new study by researchers from ICES, the Ottawa Hospital, the University of Ottawa's Department of Family Medicine and Bruyère. Health Research Institute.

The work has been published in JAMA Psychiatry.

These findings come as psychedelics, a type of hallucinogen, are growing in popularity in North America in both recreational and therapeutic contexts. Hallucinogens include drugs such as psilocybin, LSD, DMT (ayahuasca), and MDMA (ecstasy).

The study, which followed more than 9.2 million people in Ontario, Canada, found that those who visited a hallucinogen-related emergency room (ED) had a 21-fold higher risk of developing schizophrenia compared to the general population .

Even after taking into account an individual's co-occurring substance use and mental health disorders, the study found a 3.5-fold increased risk of schizophrenia.

“Our findings underscore a concerning link between hallucinogen use requiring emergency room care and an increased risk of schizophrenia,” says Dr. Daniel Myran, Canada Research Chair in Social Accountability at the University of Ottawa, ICES Adjunct Scientist, researcher at the University of Ottawa. Bruyère Health Research Institute and clinical researcher at the Ottawa Hospital.

“While there is tremendous enthusiasm for psychedelic therapy as a new mental health treatment, we must remember how early and limited the data are in terms of both benefits and risks,” Myran adds.

Published in the magazine JAMA Psychiatryresearchers analyzed health data from people aged 14 to 65 who lived in Ontario between 2008 and 2021.

The authors looked at changes in the number of emergency room visits involving hallucinogens over time, along with the risk of being diagnosed with schizophrenia after such visits.

Key findings:

• Although the annual number of emergency room visits involving hallucinogens was stable between 2008 and 2012, it increased by 86% between 2013 and 2021.

• Within three years of an emergency room visit involving hallucinogens, 4% of individuals were diagnosed with schizophrenia, compared with 0.15% of members of the general population followed for the same period – a risk that was 21 times higher.

• Individuals with an emergency visit involving hallucinogens had a 4.7 and 1.5 times higher risk of schizophrenia, respectively, compared to individuals with an emergency visit involving alcohol and cannabis.

The authors emphasize that their findings do not establish a causal link between hallucinogen use and schizophrenia and that much more information is needed about the risks associated with different types and patterns of hallucinogen use.

However, the study highlights the risks associated with the use of hallucinogens that require emergency care and possibly in individuals with an underlying susceptibility to psychosis or schizophrenia. The authors also emphasize the importance of further research and public health measures to better understand and mitigate these risks.

“Clinical trials of psychedelic-assisted psychotherapy have safeguards such as excluding individuals with a personal or family history of schizophrenia and close monitoring while participants are using hallucinogens. Our findings provide an early warning about potential risks of using hallucinogens outside the trial setting,” says Myran.

“It is also important that we can identify those at risk of developing serious side effects from psychedelics that require emergency care, so that future studies can screen for baseline risk of complications from psychedelic use and inform safe recruitment practices,” says Dr. Marco Solmi, research director at uOttawa's psychiatric unit and medical director of the On Track Early Intervention Service for Psychosis in Ottawa.