Sobel and colleagues have demonstrated deformations in the basal ganglia nuclei (caudate, putamen, globus pallidus) in children with ADHD. The more prominent the deformations, the greater the severity of symptoms. Furthermore, Sobel and colleagues have shown that stimulants may normalize the deformations. Adults with ADHD also have been reported to have deficits in anterior cingulate activation while performing similar tasks to ones that children performed. This may indicate a basal ganglia nuclei dynamic in both groups.
In children, ADHD is 3–5 times more common in boys than in girls. Some studies report an incidence ratio of as high as 5:1. The predominantly inattentive type of ADHD is found more commonly in girls than in boys. In adults, the sex ratio is closer to even.
In both children and adults, the underlying brain regions predominantly thought to be involved are frontal and prefrontal; the parietal lobe and cerebellum may also be involved. Depressed dopamine activity and decreased amounts of dopamine in the caudate, and preliminary evidence in limbic regions, have been associated with inattention and enhanced reinforcing responses to intravenous methylphenidate in adults. This concludes that dopamine dysfunction may be involved with symptoms of inattention but may also contribute to the possibility of substance abuse comorbidity.
For more on the etiology and epidemiology of ADHD, read here.
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Cite this: Stephen Soreff. Fast Five Quiz: Test Yourself on Attention-Deficit/Hyperactivity Disorder in Adults - Medscape - Aug 23, 2018.