Researchers have discovered that depression and social anxiety cause noticeable structural abnormalities in the brain, according to a recent release from the Radiological Society of North America (RSNA). The findings, which will be presented at RSNA 2017 in Chicago, were discovered by researchers at Sichuan University in Chengdu, China.
According to the press release, about 16 million Americans currently live with Major Depressive Disorder (MDD), and roughly 15 million American adults have Social Anxiety Disorder (SAD). Some clinical symptoms overlap between the two conditions, suggesting they may have similar brain mechanisms. However, very little research exists comparing cognitive structural differences.
Co-authors Youjin Zhao MD, PhD and Su Lui, MD, used MRI to assess alteration in the brain's gray matter in MDD and SAD patients, focusing on the cortex thickness of the brain.
Zhao and Lui analyzed images from 37 MDD patients, 24 SAD patients and 41 healthy control patients. Zhao and Lui found that both MDD and SAD patients, compared to the healthy control group, showed gray matter in the brain's salience and dorsal attention networks, both essential in stimulating attention, attentiveness and focus. More so, both MDD and SAD patients showed cortical thickening in the insular cortex, vital for perception and self-awareness.
"Our findings provide preliminary evidence of common and specific gray matter changes in MDD and SAD patients," Zhao said. "Future studies with larger sample sizes combined with machine learning analysis may further aid the diagnostic and prognostic value of structural MRI."
The difference between MDD and SAD patients is the thickening or thinning of the cortex. Zhao explained that the relationship remains unclear between the clinical manifestations of MDD and SAD and cortical thickening in brain regions like the anterior cingulate cortex, which controls emotion, according to the press release.
"First, it is possible that a greater cortical thickness may reflect a compensatory mechanism that is related to inflammation or other aspects of the pathophysiology," she said. "Second, greater anterior cingulate cortical thickness could be the result of both the continuous coping efforts and emotion regulation attempts of MDD and SAD patients."
Additionally, the researchers also found in SAD patients signs of disorder-specific involvement of the brain's "fear circuitry" and involvement of the visual recognition network in patients with MDD, which Zhao explained may be related to impaired selective attention and memory.