Clinical Summary: Hallucinogen-Psychosis Associations Are Confounded by Baseline Psychiatric History
Patients who present after hallucinogen-related admissions often look high risk for later psychosis, but that signal can be misleading if clinicians focus only on the substance exposure and miss the psychiatric history that came first. This study shows that baseline psychotic and other psychiatric disorders were much more common before hallucinogen-related admissions, reframing postadmission psychosis risk as a marker of underlying vulnerability rather than hallucinogen-specific causation alone.
Key Findings
- Baseline psychotic disorders were more common in the hallucinogen-related admissions cohort than in the nonhallucinogen-related admissions cohort (19.2% vs 6.3%), and baseline psychosis admissions were also higher (13.9% vs 3.7%).
- Between 30 days and 6 months following index substance-related admission, 16.4% of individuals within the hallucinogen-related index admissions cohort versus 6.6% of individuals within the nonhallucinogen-related admissions cohort received ≥1 diagnosis for psychosis (P<.001); 9.3% versus 3.3% had ≥1 subsequent admission for psychosis (P<.001).
- In unadjusted Cox models, hallucinogen-related admissions were associated with increased hazard for postindex psychosis diagnoses (HR=1.22 [95% CI =1.19–1.25]) and psychosis admissions (HR=1.16 [1.13–1.19]).
- After adjustment for baseline psychotic disorder diagnoses, the association with postindex psychosis diagnoses was reduced to HR =1.12 [1.09–1.15], and after additional adjustment for baseline clinical characteristics and demographics it was no longer significant (HR=0.97 [0.95–1.00]).
- Across adjusted models, baseline psychiatric disorders remained significant predictors of postindex diagnoses for psychosis, especially baseline psychotic admissions (HRs ranging from 1.28 to 1.35), stimulant use disorders (HRs ranging from 1.27 to 1.32), and opioid use disorder (HRs ranging from 1.28 to 1.32).
A hallucinogen-related admission does not independently signal higher short-term psychosis risk once baseline psychiatric history and other clinical factors are taken into account. In practice, premorbid psychosis and co-occurring substance use disorders matter more than the hallucinogen-related admission itself.
Practice Implications
- When evaluating psychosis after hallucinogen exposure, assess outpatient and inpatient psychiatric history; relying only on prior psychosis admissions can miss many high-risk patients because psychosis-related admissions comprised only a subset (10,719/18,131 people) of those with baseline psychotic disorders.
- Expect substantial psychiatric and substance-related comorbidity in this population: 22.5% had baseline opioid use disorder, 36.6% cannabis-related disorder, 16.2% stimulant-related disorder, and 28.1% alcohol use disorder before the first hallucinogen-related admission.
- Interpret temporality cautiously in younger patients, since the median age in the hallucinogen-related admissions cohort was 24 years [IQR=16], overlapping the typical age of onset for schizophrenia spectrum disorders.
- Plan assessment and counseling around polysubstance use rather than isolated hallucinogen exposure; only 695/6,184 individuals with ≥1 hallucinogen-related admission exclusively experienced hallucinogen-related admissions.
