Letters to the Editor
Critical Appraisal of Extended Treatment Studies in Attention-Deficit Hyperactivity Disorder
Dear Editor:
Russell Schachar and colleagues’ excellent review (1) offers a sobering and necessary balance that illustrates the current limitations of our knowledge regarding treatment effects in attention-deficit hyperactivity disorder (ADHD). With regard to the combination of pharmacologic and nonpharmacologic treatment approaches, it is instructive to note that the literature does not address an important practical issue for children responding to short-term stimulants in the classroom. We know that most treatment studies have found positive benefit for short-acting stimulants, even though these medications give a benefit for only 90 minutes, approximately. Why these short-acting medications work as well as they do throughout the school day, given their short duration of action, is an important and relatively unexplored question.
A recent article on impulse disorders casts light on this question (2). In it, Strayhorn makes the point that one aspect of working with impulse disorders concerns facilitating the development of “a positive momentum.” Perhaps this is an important clue as to why the short-acting medications work as well as they do. In theory, the longer-acting stimulants provide better coverage throughout the school day; however, many children do receive good benefit from short-acting preparations—a seeming paradox. This suggests that the sustained action of these short-acting medications might be explained in terms of the development of positive momentum. If children with ADHD “get on track” for 90 minutes at the beginning of the morning and afternoon school, their positive momentum may carry them along for the remaining time. If children are more able to achieve success in the class, albeit for a short period, their self-cognitions are more likely to be positive than negative. Perhaps this is the underlying mechanism behind the sustained benefit of short-acting medications beyond their pharmacologically effective time window. If so, facilitating positive momentum with cognitive and behavioural techniques begins to make more sense. The interaction wherein the pharmacologic effects of a short-acting stimulant allow the teacher to help the child get on a positive track may be a fruitful source of further research investigating how teachers can help children with ADHD enter the learning group.
Schachar’s article notes that currently available randomized treatment studies have some significant limitations regarding the wide array of outcomes that are important to measure for children and adolescents with this common disorder. An important and underexplored outcome is related to public health—driving safety and ADHD. Recent research emphasizes the increased risk of dangerous driving behaviour in young drivers with ADHD and other impulse disorders (3). Ongoing research in this very important area of impulsivity and dangerous driving raises the possibility of identifying high-risk groups early and developing early preventive intervention strategies for an underrecognized public health issue.
References
1. Schachar R, Jadad AR, Gauld M, Boyle M, Booker L, Snider A, and others. Attention-deficit hyperactivity disorder: critical appraisal of extended treatment studies. Can J Psychiatry 2002:47:4:337–48.
2. Strayhorn JM. Self control theory and research. Am J Child Adolesc Psychiatry 2002:41:7–16.
3. Barkley R. ADHD and accident proneness. ADHD Newsletter 2002:10:2:2–6.
Laurence Jerome, MBChB, Msc, MRCPsych, FRCPC
London, Ontario
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