Functional Networks Of Working Memory In Children With ADHD

Main Category: ADHD
Also Included In: MRI / PET / Ultrasound;  Psychology / Psychiatry;  Mental Health
Article Date: 11 Jun 2007 - 0:00 PDT

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Besides attention problems, children with attention deficit/hyperactivity disorder (ADHD) often show deficits in working memory functions. Working memory maintains and manipulates information and is crucial for every-day functioning. Methylphenidate (MPH) is a potent medication to improve the performance in several cognitive tasks. However, it is not yet clear which effect MPH has on the underlying functional networks in the brain. Recently, 6 boys with ADHD and 6 healthy boys were studied using functional magnetic resonance imaging (fMRI). Each patient was tested twice, once with MPH and once without. During imaging in the MRI Scanner, all participants performed a working memory task with increasing difficulty.

The results of the easiest task showed no differences between groups or medication conditions. In the more difficult task, ADHD patients performed better when medicated and fMRI images showed increased frontal activation. In the most difficult task, performance of medicated patients was better than that of non-medicated patients. Likewise, brain activation increased under medication, especially in frontal and parietal regions. These areas are known to be involved in working memory processes. Activation patterns under medication resembled the ones observed in healthy boys.

These preliminary findings indicate an effect of MPH on functional networks of working memory by increasing the neural activity in parietal and frontal brain regions. This holds especially for difficult tasks. As MPH leads to activation patterns similar to the ones observed in healthy boys, the medication with MPH seems to have a "normalizing" effect on brain activation in children with ADHD.

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