Summary: A major study has found that treating ADHD with stimulant medication during childhood may actually lower the long-term risk of developing serious psychotic disorders, such as schizophrenia.
The research analyzed health data from nearly 700,000 people in Finland. The findings directly challenge the common fear that ADHD stimulants might trigger psychosis; instead, the data suggests a protective effect—but only when treatment begins before the age of 13.
Key Facts
- The Age Threshold: A reduced risk of adult psychosis was specifically associated with starting methylphenidate (Ritalin/Concerta) before age 13.
- Correlation vs. Causation: While a small minority of children with ADHD do develop schizophrenia later in life, this study suggests the medication is not the cause of that risk.
- Developmental Window: The protective benefit was not observed in individuals who started treatment during adolescence or adulthood, highlighting a unique “window of opportunity” in the developing childhood brain.
- Massive Scale: The study is one of the most comprehensive to date, using advanced statistical modeling to account for regional differences in prescribing practices across an entire national population.
Source: University College Dublin
A major new study, led by scientists at University College Dublin and the University of Edinburgh and funded by the St John of God Research Foundation, has found that commonly prescribed attention deficit hyperactivity disorder (ADHD) medication in childhood may lower the long‑term risk of developing serious psychotic disorders, including schizophrenia.
Treatment with methylphenidate, the most commonly prescribed ADHD medication for children, before the age of 13 was shown to be associated with a reduced risk of psychosis in adulthood.
At a time when diagnoses of ADHD are rising rapidly worldwide, concerns about whether stimulant medications might increase the risk of psychosis have fuelled public anxiety among parents, clinicians and policymakers. This new evidence directly challenges that narrative.
No increased risk — and a possible protective effect
Focusing on nearly 4,000 young people diagnosed with ADHD, the researchers found no evidence that treatment with methylphenidate, the most commonly prescribed ADHD medication for children, increased the likelihood of developing a psychotic disorder later in life.
“We know that when children with ADHD are followed into adulthood, a small but significant minority develop psychotic disorders such as schizophrenia,” said Professor Ian Kelleher, Professor of Child and Adolescent Psychiatry at the University of Edinburgh and the study’s lead researcher, “A critical question has been whether ADHD medication causes that risk, or whether this is a case where correlation does not equal causation. Our findings suggest the medication itself is not driving that risk.”
Reassurance for families and clinicians
The researchers found no evidence that treatment with methylphenidate increased the likelihood of developing a psychotic disorder later in life.
The results are likely to offer reassurance to families weighing up treatment decisions and to clinicians concerned about long term safety.
The study, published in JAMA Psychiatry, used advanced statistical methods to examine how natural differences in ADHD prescribing practices across Finnish hospital districts influenced later psychosis risk.
Analysing health data from almost 700,000 people born in Finland, the scale of the study makes it one of the most comprehensive investigations to date into the long term mental health outcomes associated with ADHD treatment.
“Overall, these findings are reassuring,” Professor Kelleher added.
“The fact that early treatment was associated with a lower long term risk of psychosis suggests these medications may do more than manage symptoms in childhood – they may also have longer term protective effects against severe mental illness, though this requires further research.”
The authors stress that the apparent protective effect was seen only in those treated during childhood.
The same benefit was not observed among individuals diagnosed and treated during adolescence or adulthood.
Growing urgency as adult ADHD diagnoses surge
Dr Colm Healy, Research Fellow at University College Dublin and lead author of the study, said the findings highlight the need for age‑specific research as adult ADHD diagnoses continue to increase.
“There are important developmental differences between the childhood brain and the teenage or adult brain. “We can’t assume that the effects of stimulant medication will be the same across different stages of life. Given the rapid rise in adult ADHD treatment, understanding these differences is now an urgent priority.”
The researchers say the findings underline the importance of early diagnosis, careful clinical assessment and evidence‑based treatment, and provide a timely counterpoint to fears surrounding ADHD medication.
Key Questions Answered:
A: While high doses or misuse of stimulants can cause temporary symptoms, this study looked at long-term outcomes. It found that for children prescribed these meds correctly, there was no increased risk of developing a permanent psychotic disorder later in life.
A: The researchers believe there are “important developmental differences” between a child’s brain and an adult’s. Early treatment might help stabilize brain development during a critical period, whereas an older brain is already more “set” in its pathways.
A: Not necessarily. While the study is reassuring, the authors emphasize the need for “careful clinical assessment.” It provides a powerful counterpoint to fear-based narratives, helping parents and doctors make decisions based on evidence rather than anxiety.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this psychosis and psychopharmacology research news
Author: David Kearns
Source: University College Dublin
Contact: David Kearns – University College Dublin
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Methylphenidate Treatment and Risk of Psychotic Disorder” by Colm Healy, Kirstie O’Hare, Ulla Lång, Johanna Metsälä, Anna Pulakka, Jane McGrath, Maria Migone, Dolores Keating, Liana Romaniuk, David Gyllenberg, Eero Kajantie, George Perrett, Jennifer Hill, Felix Elwert, and Ian Kelleher. JAMA Psychiatry
DOI:10.1001/jamapsychiatry.2026.0152
Abstract
Methylphenidate Treatment and Risk of Psychotic Disorder
Importance
Methylphenidate is the leading pharmacological treatment for attention-deficit/hyperactivity disorder (ADHD) in childhood and adolescence. Individuals with ADHD have a higher risk of psychosis, but the long-term relationship between methylphenidate and risk of developing psychotic disorders is unknown.
Objective
To estimate the relationship between methylphenidate treatment and the risk of nonaffective psychosis in children and adolescents diagnosed with ADHD.
Design, Setting, and Participants
This cohort study included instrumental variable analysis of data linkage from multiple national Finnish registries for all individuals born from 1987 to 1997 (n = 697 289). These registries were used to identify childhood and adolescent ADHD diagnoses (age <18 years) from 2003 onwards. Data were analyzed from June 2023 to December 2025.
Exposure
Cumulative amount of treatment with methylphenidate used in 4 intervention windows: within 1, 2, 3, and 4 years after ADHD diagnosis. Hospital district prescribing propensities (average prescribing within each hospital district, within each intervention window) were used as instruments.
Main Outcome and Measures
Diagnosis of nonaffective psychotic disorder (by code from International Statistical Classification of Diseases and Related Health Problems, Tenth Revision) by the end of follow-up (December 31, 2016). Instrumental variable analyses were conducted using 2-stage least squares modeling and the Anderson-Rubin test. Risk differences (RDs) were estimated for each intervention window.
Results
Among 3956 individuals diagnosed with ADHD (3181 male [80.4%], 775 female [19.6%]; median [IQR] age, 14.16 [11.78-15.93] years), 2728 (69.0%) received methylphenidate at least once. A total of 222 individuals (5.7%) were diagnosed with nonaffective psychosis by mean (SD) age 22.16 (2.39) years (range, 19.00-29.81 years).
There was substantial variation in hospital district prescribing propensity (for example, first-year range, 0.07 to 0.30). Instrumental variable analysis indicated that sustained treatment with methylphenidate (30 mg/d) was not associated with the risk of nonaffective psychosis in the overall ADHD sample (1-year RD, −0.14; 95% CI, −0.85 to 0.42; and 4-year RD, −0.15; 95% CI, −0.49 to 0.11).
Secondary analyses indicated a reduced risk of nonaffective psychosis among individuals diagnosed in childhood (age <13 years: 3-year RD, –0.24; 95% CI, –0.45 to –0.03; P = .03; 4-year RD, –0.21; 95% CI, –0.48 to –0.07; P = .02). An insufficiently strong instrument precluded the same secondary analyses in those diagnosed in adolescence.
Conclusion and Relevance
This study of national Finnish registry data for individuals with ADHD found no overall relationship between sustained treatment with methylphenidate risk of nonaffective psychosis; in secondary analyses, a potentially protective effect of methylphenidate treatment against later psychosis in children diagnosed with ADHD was found. Further research is needed to evaluate potential effects of treatment in individuals diagnosed in adolescence and adulthood.
