Atypical Brain Activation During Simple & Complex Levels of Processing in Adult ADHD

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Abstract
Objective: Executive dysfunction in ADHD is well supported. However, recent studies suggest that more fundamental impairments may be contributing. We assessed brain function in adults with ADHD during simple and complex forms of processing. Method: We used functional magnetic resonance imaging with forward and backward digit spans to investigate number repetitions and complex working memory function. If pathology is limited to higher cognitive operations, group differences should be confined to the backward condition. Results: During the forward digit span, ADHD participants exhibited greater activation of LH linguistic processing areas and increased activation of right frontal and parietal cortices. During the backward digit span, they exhibited greater activation of LH linguistic processing areas and failed to activate bilateral parietal regions important for the complex executive operations. Conclusion: Abnormal brain function among adult ADHD participants was not limited to complex executive functions. Abnormal processing of numeric stimuli was indicated during both simple and complex cognitive operations. (J. of Att. Dis. 2007;11(2) 125-140)