People with a history of psychosis often also have attention-deficit/hyperactivity disorder (ADHD). However, treating this condition presents doctors with a clinical dilemma: psychostimulants are considered effective for ADHD, but are suspected of increasing the risk of psychotic episodes. A new international study involving the Central Institute of Mental Health (CIMH) now provides important insights: No increased risk of recurrent psychotic episodes following the initiation of pharmacological ADHD treatment was observed.
ADHD and Psychosis: A Common but Challenging Comorbidity
ADHD occurs relatively frequently in people with psychosis: according to estimates, approximately 10 to 15 percent of those affected also have ADHD. In clinical practice, this comorbidity poses a particular challenge, as the effective treatment of ADHD with psychostimulants or atomoxetine has been linked to potential risks of psychotic episodes. An international study involving the Central Institute of Mental Health (CIMH) in cooperation with the Karolinska Institutet in Stockholm, Sweden, now provides new insights on this topic: No increased risk of recurrent psychotic episodes following the initiation of pharmacological ADHD treatment was observed.
Large-scale registry study: No increase in the risk of psychosis
The results are based on a large population-based analysis of Swedish registry data from approximately 3,700 adults diagnosed with psychosis and concurrent ADHD. The study examined whether the risk of recurrent psychotic episodes changes after the initiation of treatment with psychostimulants. The analysis shows that no statistically significant increase in the risk of relapse was observed.
“Our findings challenge a widespread clinical assumption that ADHD medications should generally be avoided in people with psychosis,” says Prof. Dr. Dr. Patrick Bach, lead author of the study and head of a research group at the Central Institute of Mental Health. “We see no increased risk of recurrent episodes after treatment begins. This can give physicians greater confidence in managing this complex patient group.”
Individual risk assessment remains important
At the same time, the researchers emphasize that the findings should not be interpreted as a blanket all-clear. “Our data do not replace an individual risk assessment,” researcher Bach makes clear. “The decision for or against medication for ADHD must continue to be made on a case-by-case basis, taking into account medical history, current symptoms, and close clinical monitoring.”
The study results are particularly relevant given that ADHD is frequently underdiagnosed and, consequently, rarely treated in people with psychosis. At the same time, there is often significant reluctance in clinical practice regarding the use of stimulants. The current data suggest that this caution should be viewed in a more nuanced way.
More evidence for complex psychiatric disorders
“People with complex psychiatric comorbidities often fall through the cracks in the healthcare system,” says Bach. “Our study helps improve the evidence base for their treatment and reduce existing uncertainties.”
The findings were published in the journal “Translational Psychiatry” and further supported by a supplementary analysis from the same international research collaboration.
This second study addressed a clinically significant question: whether prescribing stimulants to patients with current or past stimulant dependence increases the risk of hospitalizations, for example due to intoxication. The analysis showed no corresponding risk signal. Rather, there was a tendency toward lower rates of stimulant-related hospitalizations after the start of treatment. These results also suggest that pharmacological treatment is possible — provided indications are carefully assessed and individual risks are weighed — without being associated with increased risks.
Both studies make an important contribution to the evidence-based advancement of treatment for patients with co-occurring mental disorders.
Publication
Bach, P, Franck, J, Hällgren, J et al. Prescription psychostimulants, atomoxetine and the risk of psychosis in adults with history of psychosis: a population-based cohort study. Transl Psychiatry 16, 226 (2026). DOI: https://doi.org/10.1038/s41398-026-03998-4
https://www.nature.com/articles/s41398-026-03998-4
Another study
Bach P, Franck J, Hällgren J, et al. Prescription psychostimulants or atomoxetine and the risk of stimulant-related hospital admissions in adults with and without stimulant use disorder: a Swedish population-based within-individual observational study. Lancet Reg Health Eur. 2026;65:101658. DOI: doi.org/10.1016/j.lanepe.2026.101658
https://www.sciencedirect.com/science/article/pii/S2666776226000700