Attention-deficit hyperactivity disorder (ADHD) is one of the most common psychiatric disorders among school-age children. Associated with behavioral and academic difficulties, ADHD persists into adolescence and adulthood, often with poor outcome (Barkley et al., 1990; Biederman et al., 1991). Numerous short-term, well-controlled studies have shown that stimulant medications such as methylphenidate (MPH), dextroamphetamine, and pemoline are effective in treating ADHD symptoms of restlessness, inattentiveness, and impulsivity (Jadad et al., 1999; Shukla and Otten, 1999). However, the benefits of medication are short-lived and disappear after it is discontinued.
Although few studies exist, those available suggest that long-term treatment with stimulants for ADHD has little impact on outcome for these children. Recent placebo-controlled studies of 1 to 2 years' duration suggest that stimulants continue to reduce symptoms of ADHD, but cumulative benefits in psychosocial, academic, and family functioning have not yet been documented (Jadad et al., 1999; MTA Cooperative Group, 1999). Barkley et al. (1990) and Biederman et al. (1996a) documented that children with ADHD continued to have significant academic, social, and psychiatric impairment in adolescence despite substantial use of medications and other interventions.
Given that stimulant effects dissipate rapidly, noncompliance with treatment is a likely reason for suboptimal outcome in ADHD. Available studies provide limited information about long-term adherence to stimulant medication. Most studies examined discontinuation of stimulant treatment over weeks to months and had small samples after attrition. One previous study examined adherence over a 1-year period, but combined children who did not start treatment with those who discontinued. Approximately 45% to 55% of children with ADHD terminated the treatment protocol within several months, and subjects who continued in treatment missed 25% to 35% of pills prescribed. Few predictors of medication compliance were noted. Older children, those with lower IQ, and those with greater difficulty with attention were more likely to miss doses....
