Acute Effects of Stimulant Medication on Gray Matter and White Matter Indices in Healthy Controls and Adults With ADHD.

INTRODUCTION

Short-latency changes in gray matter volume (GMV) and diffusion tensor imaging (DTI) indices have been reported for sleep deprivation, hypercapnia, short-lasting visual and nociceptive stimuli and within a couple of hours after ingestion of single-dose psychoactive drugs.

METHODS

In the current study, we investigated acute effects of single-dose stimulant medication (CS) on gray and white matter indices using voxel- and surface-based morphometry (VBM and SBM) and diffusion tensor imaging (DTI) in 78 participants, consisting of 42 healthy controls and 36 age and gender matched adults with ADHD. Heart rate and blood pressure were also measured under similar conditions as physiological covariates.

RESULTS

For the group as a whole (n = 78), acute ingestion of CS caused apparent increase in GMV in bilateral operculum, insula, cingulate and paracingulate cortices, fusiform gyrus, superior, middle and inferior gyri of the temporal cortex and in right putamen and caudate nucleus and caused an even more wide-spread right-lateralized apparent increase in cortical thickness; the apparent changes in cortical thickness were also seen in patients with ADHD but not in healthy controls. CS administration also increased fractional anisotropy (FA) in bilateral corpus collosum, corona radiata and right superior longitudinal fasciculus, with no significant differences in VBM, SBM or FA between healthy controls and ADHD patients before or after CS ingestion. Heart rate and blood pressure increased significantly for both groups after CS ingestion, with ADHD patients displaying greater increase in systolic blood pressure compared to healthy controls. No significant correlation was detected between the structural gray matter and white matter changes and changes in heart rate or blood pressure.

CONCLUSION

Combining VBM, SBM and DTI indices, our study is the first to show apparent structural changes in the brain in adults with ADHD within 1-2 h after CS ingestion. Currently it is not known what causes these apparent structural changes but notwithstanding that, these changes should be taken into account in longitudinal VBM, SBM and DTI studies.