ED visits for hallucinogen use linked to increased risk for schizophrenia

Key takeaways:

• Hallucinogen-related ED visits were linked to higher risk for developing schizophrenia spectrum disorder (SSD).
• Hallucinogen-related ED visits similarly increased SSD risk across age.

Individuals who visited the ED for hallucinogen use had a greater risk for developing a schizophrenia spectrum disorder compared with the general population and ED visits for other substances, researchers found.

Although recreational and medicinal use of hallucinogens has substantially increased in North America, there is limited research concerning the effect of hallucinogens on risk for psychosis and schizophrenia spectrum disorder (SSD), according to the researchers.

“Such knowledge is urgently required to help clinicians, patients and individuals who use hallucinogens recreationally to understand associated risks, with implications for clinical, prevention and harm-reduction efforts,” Daniel T. Myran, MD, MPH, CCFP, FRCPC, associate scientist at Ottawa Hospital Research Institute and assistant professor in the department of family medicine at University of Ottawa, and colleagues wrote in JAMA Psychiatry.

To address this, the researchers performed a population-based, retrospective cohort study from 2008 to 2021 to determine whether visiting an ED due to hallucinogen use increased the risk for developing SSD among individuals with no history of psychosis.

The study included all residents of Ontario, Canada, aged 14 to 65 years who were eligible for the Ontario health insurance program (n = 9,244,292; 50.2% women; mean age, 40.37 years). The researchers calculated the primary outcome, development of SSD, using a medical record-validated algorithm (sensitivity, 91.6%; specificity, 61.3%). Median follow-up was 5.1 years.

Myran and colleagues found that of the total population, 5,217 (0.1%) had an ED visit related to hallucinogen use, largely due to harmful use (36.6%) and intoxication (22.2%).

Compared with the general population, this group appeared younger (mean age, 26.69 vs. 40.37 years) and was comprised of more men (70.8% vs. 49.8%). They also were more likely to have been hospitalized or visited the ED for substance abuse (50.9% vs. 2.4%) or mental health disorders (32.5% vs. 3.5%) in the past 5 years.

Results also showed the rate of incident ED visits was relatively steady from 2008 to 2012 but increased by 86.4% between 2013 and 2021 (3.4 vs. 6.4 per 100,000 individuals).

The researchers observed that within 3 years, 208 (3.99%) of the individuals who visited the ED for hallucinogen use developed SSD, compared with 13,639 (0.15%) individuals from the general population.

After adjusting for age and sex, they found that risk for developing an SSD was significantly greater for individuals with ED visits due to hallucinogen use (HR = 21.32; 95% CI, 18.58-24.47) and hallucinogen-induced psychosis (HR = 128.63; 95% CI, 93.15-177.61) compared with the general population.

Additionally, after adjusting for income, rurality, immigration status, comorbid substance use and mental health care in the past 5 years, the researchers found that individuals with a hallucinogen-use related ED visit had greater risk for SSD (HR = 3.53; 95% CI, 3.05-4.09) compared with the general population.

A secondary analysis of the fully adjusted model revealed that at 3-year follow up, individuals who visited the ED for hallucinogen use had an increased risk for SSD compared with ED visits for alcohol (HR = 4.66; 95% CI, 3.82-5.68) and cannabis (HR = 1.47; 95% CI, 1.21-1.8).

The researchers noted several limitations to this study, including a lack of data concerning the type of hallucinogen used and potential contaminants in illicitly obtained hallucinogens.

“Given rapid increases in interest in and adult use of hallucinogens and the increase in ED visits involving hallucinogens found in this study, ongoing research is needed to clarify the observed association between hallucinogen use and development of SSD,” Myran and colleagues wrote.