Researchers analyzed data from many clinical trials involving over 25,000 people aged five and older who met standard criteria for attention deficit hyperactivity disorder. The study looked at how different doses of common medications like methylphenidate, amphetamines, guanfacine, atomoxetine, and modafinil affected symptom control and side effects over a period of up to five years.
The results showed a clear pattern for stimulants. For methylphenidate, symptom improvement increased as the dose went up to 45 milligrams per day for children and adolescents. For amphetamines, improvement plateaued around 25 milligrams per day in younger patients and 50 milligrams per day in adults. Going higher did not provide extra benefit.
Safety concerns emerged alongside these findings. The likelihood of stopping treatment due to side effects rose with higher doses of amphetamines and methylphenidate in adults. Data for atomoxetine and modafinil did not show a clear link between dose and effect. The study authors noted that estimates for higher doses had wide uncertainty intervals, meaning the exact impact is less certain there. These findings can help doctors and patients make informed choices about dosage.