Physiology of ADHD

Physiology is defined as the study of the function or mechanism of how a biological system works. In order to understand the onset and proliferation of ADHD, we must understand how a normal patient’s brain functions, or the patient’s physiology, before we can understand the differences that occur within a patient diagnosed with ADHD.

In one study conducted in 2004 using an MRI scanner at Yale University (2), the brains of 27 children (11 girls and 16 boys) with ADHD and those of 46 children of equal age and sex proportion were scanned and analyzed at UCLA. Elizabeth Sowell, MD and Bradley Peterson, MD observed significant differences in the brain structure of children with ADHD versus those who had not been diagnosed. Children with ADHD were observed to have brains with reduced size in the anterior temporal lobes on both sides of their brain. In areas of the brain previously identified as being regions which control attention and impulsive control, such as the posterior temporal and inferior parietal cortices, children with ADHD were found to have relatively larger increases in volumes of grey matter as compared with those who were not diagnosed. The following images show the differences in sizes of anatomy in healthy individuals brains compared with those diagnosed with ADHD.

In another study conducted by Julie Schweitzer (3), brain scans were taken in six men diagnosed with ADHD and compared with the control, which consisted of six healthy men of matched age and health characteristics. “What we’ve seen is that more areas of the brain are involved”, said Schweitzer (1), who used the latest brain technology (MRI) to reveal the brain’s inner workings. In the table shown, the relative anatomy sizes of the different regions of the men’s brains are compared.

Ultimately what the research conducted shows is that more activity is observed in brains of those with ADHD while completing tasks as compared with those who are healthy. This is thought to be caused by increased grey matter density in brains of patients diagnosed with ADHD, as well as reduced temporal lobe sizes. Check back next week for a more in depth discussion of the symptoms associated with ADHD. 

(1) "Establishing a Comprehensive ADHD Research and Treatment Program." UC Davis Health System Feature Story: Establishing a Comprehensive... N.p., n.d. Web. 16 Sept. 2013.

(2) Rosack, Jim. "Brain Scans Reveal Physiology of ADHD." Psychiatryonline.com. N.p., n.d. Web.

(3) Schweitzer, Julie, PhD. "Alterations in the Functional Anatomy of Working Memory in Adult Attention Deficit Hyperactivity Disorder." N.p., 1 Feb. 2000. Web.