Long-Term Tolerability and Safety of Pharmacological Treatment of Adult Attention-Deficit/Hyperactivity Disorder: A 6-Year Prospective Naturalistic Study

BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) is a behavioral disorder typically treated with stimulants and atomoxetine. Data on long-term tolerability and safety of such pharmacological treatment in subjects diagnosed in adulthood are limited. METHODS: A cohort of adults diagnosed with ADHD according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria was followed-up on an average of 6 years after first evaluation. Of 168 adults, 112 (67%) who initiated medication were available for follow-up. Data were obtained from patient record data, self-report forms, and a telephone interview. RESULTS: Of the 112 participants assessed, 57 (51%) were still on treatment with methylphenidate (MPH) at follow-up and 55 (49%) had discontinued. The 3 leading reasons for discontinuing treatment with MPH were lack of effect (29%), elevated mood or hypomania (11%), and losing contact with the prescribing physician (9%). The most common adverse effects in subjects still on treatment with MPH were decreased appetite (28%), dry mouth (24%), anxiousness/restlessness and increased pulse frequency (19% each), decreased sexual desire (17%), and perspiration (15%). Subjects still on treatment reported increased quality of life, a higher level of functioning, and a greater understanding of their way of functioning from those being close compared with nonmedicated subjects. CONCLUSIONS: The high attrition rate underscores the need for further research to identify possible modes to increase retention to treatment. Those diagnosed with ADHD and on long-term treatment with stimulants experience mild and tolerable adverse effects.