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Stimulant treatment over five years: adherence, effectiveness, and adverse effects.

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Department of Psychiatry, The Hospital for Sick Children and the University of Toronto, Research Institute, The Hospital for Sick Children, University of Toronto, Ontario, Canada.



To evaluate the impact of adherence and medication status on effectiveness and adverse effects of stimulant use in children with attention-deficit/hyperactivity disorder (ADHD) over 5 years.


Seventy-nine of 91 participants in a 12-month randomized controlled trial of methylphenidate and parent groups enrolled in a follow-up study. Adherence to stimulants, treatment response, and adverse effects were evaluated annually for 5 years. Changes in teacher-reported symptoms and parent-reported adverse effects were compared at 2, 3, 4, and 5 years for 3 groups: adherents, nonadherents on medication, or nonadherents off medication. Controlling for age, gender, and baseline severity, adherence status and medication status were evaluated as correlates of teacher-reported ADHD symptom scores at each year using multiple regression analyses.


At 2 years, adherents (n = 41) showed greater improvement in teacher-reported symptoms than those off medication (n = 16) and equivalent response to nonadherents on stimulants (n = 16) (p =.02). At 5 years, adherents (n = 16) showed greater improvement in teacher-reported symptoms than nonadherents on stimulants (n = 15) and those off medication (n = 14) (p =.04). At year 2 medication status (beta = 4.67 [0.40-8.95, p =.033]) and at year 5 adherence status (beta = 7.23 [3.01-11.44, p =.001]) correlated with higher teacher-reported symptom scores. Clinically significant adverse effects were present for 5 years, most commonly loss of appetite.


Psychostimulants improve ADHD symptoms for up to 5 years, but adverse effects persist.

[Indexed for MEDLINE]

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