Prefrontal oxygenation during working memory in ADHD.
OBJECTIVE
Deficits in working memory have been repeatedly found on a behavioural level in children with attention-deficit/hyperactivity disorder (ADHD). Functional brain imaging studies have revealed evidence for alterations in the prefrontal cortex associated with working memory. So far it remains unresolved whether object (OWM) and spatial visual working memory (SWM) are distinctly impaired in ADHD. We investigated this issue with the fist multi-channel functional near-infrared spectroscopy study of children with ADHD.


METHODS
We investigated 19 children with ADHD combined type (DSM-IV) and 19 controls matched for age (8-15years), sex, handedness, and intelligence during a working memory task assessing OWM and SWM separately, and a control condition (CON). Prefrontal brain activity was measured by concentration changes of oxygenated haemoglobin.


RESULTS
Working memory performance showed significant differences for conditions (OWM>SWM>CON), but no differences between groups. Cortical prefrontal activation was significantly higher for OWM and SWM in contrast to CON, again with no differences between groups.


CONCLUSIONS
We found no indication for an altered prefrontal processing during OWM and SWM tasks in ADHD children compared to controls. Reviewing the existing imaging literature on working memory in ADHD and considering the present data, we discuss possible confounding factors relevant for brain activity in previous, the current, and future investigations. Thus, it is of high importance to capture developmental trajectories, task specific discrepancies, and effects of permanent medication intake in future studies.
Schecklmann
Martin
M
University of Wuerzburg, Department of Psychiatry, Psychosomatics and Psychotherapy, University Hospital Wuerzburg, 97080 Wuerzburg, Germany. schecklman_m@klinik.uni-wuerzburg.de
Romanos
Marcel
M
Bretscher
Franziska
F
Plichta
Michael M
MM
Warnke
Andreas
A
Fallgatter
Andreas J
AJ
D000704:Analysis of Variance; D001289:Attention Deficit Disorder with Hyperactivity / Q000503:physiopathology*; D001931:Brain Mapping / Q000379:methods; D002648:Child; D004569:Electroencephalography; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D008570:Memory, Short-Term; D010100:Oxygen / Q000378:metabolism*; D017397:Prefrontal Cortex / Q000503:physiopathology*; D019265:Spectroscopy, Near-Infrared / Q000379:methods; D013647:Task Performance and Analysis
D006454:Hemoglobins; D010100:Oxygen