An FMRI study of the effects of psychostimulants on default-mode processing during Stroop task performance in youths with ADHD.
OBJECTIVE
The authors examined the effect of psychostimulants on brain activity in children and adolescents with ADHD performing the Stroop Color and Word Test.


METHODS
The authors acquired 52 functional MRI scans in 16 youths with ADHD who were known responders to stimulant medication and 20 healthy comparison youths. Participants with ADHD were scanned on and off medication in a counterbalanced design, and comparison subjects were scanned once without medication.


RESULTS
Stimulant medication significantly improved suppression of default-mode activity in the ventral anterior cingulate cortex in the ADHD group. When off medication, youths with ADHD were unable to suppress default-mode activity to the same degree as comparison subjects, whereas when on medication, they suppressed this activity to comparison group levels. Greater activation of the lateral prefrontal cortex when off medication predicted a greater reduction in ADHD symptoms when on medication. Granger causality analyses demonstrated that activity in the lateral prefrontal and ventral anterior cingulate cortices mutually influenced one another but that the influence of the ventral anterior cingulate cortex on the lateral prefrontal cortex was significantly reduced in youths with ADHD off medication relative to comparison subjects and increased significantly to normal levels when ADHD youths were on medication.


CONCLUSIONS
Psychostimulants in youths with ADHD improved suppression of default-mode activity in the ventral anterior cingulate and posterior cingulate cortices, components of a circuit in which activity has been shown to correlate with the degree of mind-wandering during attentional tasks. Stimulants seem to improve symptoms in youths with ADHD by normalizing activity within this circuit and improving its functional interactions with the lateral prefrontal cortex.
Peterson
Bradley S
BS
Department of Psychiatry, New York State Psychiatric Institute and College of Physicians and Surgeons, Columbia University, New York, 10032, USA. petersob@childpsych.columbia.edu
Potenza
Marc N
MN
Wang
Zhishun
Z
Zhu
Hongtu
H
Martin
Andrés
A
Marsh
Rachel
R
Plessen
Kerstin J
KJ
Yu
Shan
S
D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy* / Q000503:physiopathology; D000697:Central Nervous System Stimulants / Q000494:pharmacology / Q000627:therapeutic use*; D002648:Child; D005260:Female; D007839:Functional Laterality / Q000187:drug effects* / Q000502:physiology; D006179:Gyrus Cinguli / Q000187:drug effects / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D009434:Neural Pathways / Q000187:drug effects / Q000503:physiopathology; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D017397:Prefrontal Cortex / Q000187:drug effects / Q000503:physiopathology
D000697:Central Nervous System Stimulants