Individual differences in subcortical microstructure organization reflect reaction time performances during a flanker task: a diffusion tensor imaging study in children with and without ADHD.

The results of several previous magnetic resonance imaging studies suggest that the fronto-striato-thalamic circuitry is involved in the pathophysiology of attention-deficit/hyperactivity disorder (ADHD). However, few studies have investigated the putative association between quantitative diffusion tensor imaging measurements of subcortical gray matter and subject task performances in children with ADHD. Here, we examined whether reaction time (RT) parameters during a flanker task were correlated with mean diffusivity (MD) measurements in the basal ganglia and thalamus in children with ADHD and in controls. For the study group as a whole, both the mean RT and the intra-individual variability in RTs were found to be significantly correlated with MD measurements in the right and left caudate, putamen and thalamus. In contrast, the correlation between the interference effect and MD failed to reach statistical significance. The present results may advance our understanding of the anatomical substrates of ADHD.