Neuroscientists have observed a negative association between anterior cingulate cortex volume and depressive symptoms. Their findings, published in the journal Psychiatry Research: Neuroimaging, highlight that depression is associated with changes to the physical anatomy of the brain.
“Depression appears to be associated with a smaller and sometimes larger size within some brain regions,” explained study author E. Sherwood Brown, the Lou and Ellen McGinley Distinguished Chair in Psychiatric Research at the University of Texas Southwestern Medical Center and director of the Psychoneuroendocrine Research Program. “The anterior cingulate cortex is a brain region that is thought to be involved in emotional regulation. However, prior findings about whether the ACC volume is different in depression are somewhat mixed.”
For their new study, the researchers examined data from 1803 adults who had participated in the Dallas Heart Study, “a large study that obtained a variety of data, including regional brain volumes, on a large epidemiological sample of Dallas County residents,” Brown said. Importantly, the participants also completed the Quick Inventory of Depressive Symptomatology Self-Report, a validated assessment of depressive symptoms.
Participants were considered to have heightened levels of depressive symptoms if they reported symptoms such as sadness, unusual changes in appetite, suicidal thoughts, feeling sluggish, and losing interest in other people or activities.
Heightened levels of depressive symptoms were associated with reduced right ACC volume (but not left ACC volume) after controlling for demographic factors and intracranial volume, indicating that “this important brain region for emotional regulation may be different in people with depression,” Brown explained. The right ACC is implicated in a broad range of cognitive processes, including the regulation of emotional conflict and optimistic biases.
The researchers noted that their findings are in line with previous research that examined patients diagnosed with depression. The previous research, however, had utilized relatively small sample sizes.
“A common trade off in clinical research is between the size of the sample and the level of detail of the data,” Brown told PsyPost. “It is much easier to collect very detailed information in a small group of research participants than in thousands. In this study depressive symptom severity was assessed with a validated scale. However, we do not know with certainty which participants had an actual diagnosis of major depressive disorder. We also do not have information about their depressive symptoms over time.”
The study also cannot address the issue of causality.
“Cause and effect is difficult to determine in many studies,” Brown explained. “Smaller ACC volume could be either an effect of depression or be a risk factor for the development of depression. Studies with longitudinal designs that follow people over time would be needed to determine whether ACC volume predicts the development of depression or occurs as a consequence of depression.”
The study, “Anterior cingulate cortex in individuals with depressive symptoms: A structural MRI study“, was authored by Hicham M.Ibrahim, Alexandra Kulikova, Huy Ly, A. John Rush, and E. Sherwood Brown.