Who stops ADHD medication early — few reliable predictors in adults, across 1 million users

Bottom line

Across health records from eight countries and regions, between 38% and 68% of adults who started ADHD medication stopped early, defined as a gap of 180 days or more between dispensations. The study tested 23 psychiatric and neurological indicators as predictors. In adults, two survived: schizophrenia and tic disorders, each raising the rate of stopping by about a quarter. Neither held up once US data were excluded. For adults and adolescents, what you were diagnosed with alongside ADHD told the researchers little about who would stop.

The research

Brikell and colleagues used health records covering 1,000,411 new ADHD medication users (44% female) who started between 2011 and 2020, then estimated how comorbidity, severity and other psychotropic medication use related to early discontinuation, separately by age group and sex.

Discontinuation rates by age at starting: children 19–61%, adolescents 37–68%, young adults 52–67%, adults 38–68%. Statistical heterogeneity was substantial and largely driven by US estimates. The authors describe marked cross-country variation, particularly in the US, and read it as evidence of system-level influences on treatment patterns.

Predictors, by age group. Children: intellectual disability, autism and use of other psychotropic medication predicted earlier stopping (hazard ratios 1.32–1.51), while conduct or oppositional defiant disorder was protective (HR 0.83, 95% CI 0.73–0.94). Adolescents: no indicator stayed significant after correcting for testing many hypotheses. Young adults: conduct or oppositional defiant disorder predicted earlier stopping (HR 1.42, 95% CI 1.30–1.55), the opposite direction from children. Adults: schizophrenia (HR 1.25, 95% CI 1.09–1.44) and tic disorders (HR 1.27, 95% CI 1.11–1.46). Excluding the US, those adult associations were no longer significant, and different ones appeared: eating disorders and antidepressant or anxiolytic use were protective in adults. Sex differences were limited.

Limits worth carrying. This is dispensing data, so it shows when a prescription stopped being filled, not why. A 180-day gap can include people who stopped by agreement with their prescriber. Records come from eight different health systems, and the authors attribute part of the variation to system-level influences.

What this means

If you are an adult wondering whether you are the kind of person who stops, the study offers no reliable profile. Comorbidity explained little, and the strongest adult predictors were small and did not replicate outside the US. The authors conclude that healthcare context shapes persistence, and the US differed most from the other countries. The companion question, why people say they stopped, has a different answer in a 2026 Danish survey covered in What predicts whether you stay on ADHD medication.

Read next on this site:

• ADHD medication — what to expect from stimulants and non-stimulants, and how the titration period goes.
• The medication cliff — when a medication that worked seems to stop working, which is a different situation from a gap in filling it.
• Shame and adult ADHD — the belief and stigma side of the decision to stop.