A common and legitimate concern that is often voiced by parents when considering medication treatment for their child’s ADHD symptoms relates to the effects of these agents on the developing
from Rubia et al., 2009
brain. Raising some alarm have been findings from some animal studies that have suggested detrimental long-term changes; however, these studies often use very high doses administered intravenously. Neruoimaging studies in people on this question have slowly been accumulating to the point that there is a critical mass to review for common findings. This review paper by Spencer and colleagues that was published in the Journal of Clinical Psychiatry offers a summary of neuroimaging studies that have examined structural and functional changes related to ADHD treatment with stimulants.
A total of 29 studies were identified that met the authors’ inclusion criteria. Among them were 20 functional MRI studies, 6 structural MRI studies, and 3 spectroscopy studies. Between studies, a great deal of variability was found related to methodology. Despite this fact, however, overall results were fairly consistent in finding that treatment with stimulants resulted in brain structure and function closer to non-ADHD controls and farther from ADHD patients who were not treated with medications. Related to the structural MRI studies, the attenuation of structural “abnormalities” tended to be in specific to particular regions rather than reflecting overall changes in grey or white matter volume. Functional MRI studies were relatively consistent regarding findings with the striatum and anterior cingulate gyrus while the prefrontal cortex showed the most variability in results across studies.
The authors concluded that oral doses of stimulants tend to attenuate the brain alterations that have been identified in ADHD.
While this study should be somewhat reassuring to both clinicians and parents alike, it is important in my view not to take these results too far. Most of the studies reviewed were naturalistic in design which means that assignment to medication or not was not random and thus other factors might account for group differences. In addition, these studies are unable to detect more subtle changes that may be occurring on a smaller scale or over long periods of time.
Reference
Spencer T, et al. Effect of Psychostimulants on Brain Structure and Function in ADHD: A Qualitative Literature Review of MRI-Based Neuroimaging Studies. J Clin Psychiatry 74(9):902-917, 2013.