Writing in Pediatrics Richard M. Schefﬂer and colleagues reported that elementary-aged children who took medication for ADHD had higher mathematics and reading scores than their unmedicated peers with ADHD. The research team identified individuals in the Early Childhood Longitudinal Study—Kindergarten Class data set whose parents repeatedly reported that they had been diagnosed with ADHD and compared the achievement data for those children with ADHD whose parents said their child had taken medication to the achievement of those children with ADHD whose parents said their child had not taken medication. The scores of the children who had taken medication were about two or three tenths of a school year higher than those of the children who had not taken medication.
Although these findings extend the scientific understanding of psychopharmacologic treatment of ADHD, it is important to note that they are essentially correlational, not experimental. Although the study is very well done (uses a good data set, sophisitcated statistical analysis, etc.), the children were not randomly assigned to medication and non-medication conditions. It is possible that (a) some other factors explain why some children were or were not medicated, and that other factor may be the cause of the differences in achievement or (b) that children who had higher achievement were simply less likely to be medicated.
Here’s the abstract:
Scheffler, R. M., Brown, T. T., Fulton, B. D., Hinshaw, S. P., Levine, P., and Stone, S. (2009). Medication use and academic achievement during elementary school positive association between attention-deficit/hyperactivity disorder. Pediatrics, 123, 1273-1279.
OBJECTIVE. Approximately 4.4 million (7.8%) children in the United States have been diagnosed with attention-deﬁcit/hyperactivity disorder, and 56% of affected children take prescription medications to treat the disorder. Attention-deﬁcit/hyperactivity disorder is strongly linked with low academic achievement, but the association between medication use and academic achievement in school settings is largely unknown. Our objective was to determine if reported medication use for attention-deﬁcit/hyperactivity disorder is positively associated with academic achievement during elementary school.
METHOD. To estimate the association between reported medication use and stan dardized mathematics and reading achievement scores for a US sample of 594 children with attention-deﬁcit/hyperactivity disorder, we used 5 survey waves between kindergarten and ﬁfth grade from the nationally representative Early Childhood Longitudinal Study—Kindergarten Class of 1998 –1999 to estimate a ﬁrst-differenced regression model, which controlled for time-invariant confounding variables.
RESULTS. Medicated children had a mean mathematics score that was 2.9 points higher than the mean score of unmedicated peers with attention-deﬁcit/hyperactivity disorder. Children who were medicated for a longer duration (at > 2 waves) had a mean reading score that was 5.4 points higher than the mean score of unmedicated peers with attention-deﬁcit/hyperactivity disorder. The medication-reading association was lower for children who had an individualized education program than for those without such educational accom modation.
CONCLUSIONS. The ﬁnding of a positive association between medication use and standardized mathematics and reading test scores is important, given the high prevalence of attention-deﬁcit/hyperactivity disorder and its association with low academic achievement. The 2.9-point mathematics and 5.4-point reading score differences are comparable with score gains of 0.19 and 0.29 school years, respectively, but these gains are insufﬁcient to eliminate the test-score gap between children with attention-deﬁcit/hyperactivity disorder and those without the disorder. Long-term trials are needed to better understand the relationship between medication use and academic achievement.
As reported in the abstract, there is more to the results. First, note that the reading differences appeared only for children whose parents reported that they were medicated for two or more surveys. Second, longer-term use of medication was associated with higher achievement in general; this finding strengthens the case that the achievement differences are the result of the therapy and blunts the correlation-cause argument I noted earlier in this post. Third, the reading achievement effect for students with IEPs was less than for those without IEPs; although additional research is needed, this finding suggests that when ADHD is co-morbid with other problems (e.g., LD), the benefits of medication may be lesser. Last, and especially important, the achievement of the children with ADHD who took medication was not improved to the “normal” level.
Link to the Pediatrics page for the study.