Stimulant use not causally associated with psychotic experiences

There is no evidence to support a causal link between stimulant prescriptions and psychotic experiences, according to a study.

Researchers conducted a target trial emulation using data from the Adolescent Brain Cognitive Development Study. They looked at children between 9 and 14 years of age and estimated treatment (stimulant prescription) propensities using covariates indexing demographic factors and mental illness severity.

The study outcome was the average causal effect of first stimulant prescription on psychotic experiences over a 1-year follow-up. Inverse probability of treatment weighting followed by standardization (doubly robust estimation) was used in the analysis.

The analysis included 8,391 participants from the Adolescent Brain Cognitive Development Study. Of these, 460 (5.5 percent) received at least one stimulant prescription. Unweighted analyses showed stimulant prescription to be associated with increased odds of subsequent psychotic experiences (odds ratio [OR], 1.46, 95 percent CI, 1.15–1.84). The relationship also held in the other direction, such that psychotic experiences at baseline also predicted a higher likelihood of receiving subsequent stimulant treatment (OR, 1.93, 95 percent CI, 1.57–2.37).

After applying doubly robust methods, the analysis indicated no evidence that stimulant prescription had a causal effect on the subsequent occurrence of psychotic experiences (OR, 1.09, 95 percent CI, 0.71–1.56).

The findings suggest that the association between stimulants and psychotic experiences may be confounded by factors that both increase probability of stimulant prescription and lead to psychotic experiences.