Corpus callosum anatomy in chronically treated and stimulant naïve ADHD

Objective: To determine the effect of chronic stimulant treatment on corpus callosum (CC) size in children with ADHD using volumetric and area measurements. Previously published research indicated possible medication effects on specific areas of the CC. Method: Measurements of the CC from anatomical MRIs were obtained from children aged 9-16 in three diagnostic groups (a) chronically treated ADHD, (b) stimulant-naïve ADHD, and (c) typically developing children. Results: The three groups did not differ in overall CC volume. Additional analyses found differences in the area of the splenium, with the treatment-naïve group exhibiting the smallest area. Conclusions: Previously reported reductions of CC size in ADHD samples do not appear to be a result of chronic stimulant treatment. The current study suggested a trend toward normalization of splenium size for participants treated with stimulant medication.