Experts at the University of Texas Southwestern Medical Center found that a decrease in the volume of the anterior cingulate cortex, an important area of the brain for processing emotions, is associated with the appearance of symptoms of depression. They mentioned this in an article in the journal Psychiatric Research: Neuroimaging.
The researchers looked at data from 1,803 adult volunteers who had undergone extensive examinations, including brain MRI scans, and also completed a questionnaire on symptoms of depression. Some volunteers reported sadness, lethargy, loss of interest in other people and activities, loss of appetite, and suicidal thoughts.
More pronounced symptoms of depression were associated with a decrease in the volume of the right side of the anterior cingulate cortex, an area of the brain involved in regulating heart rate and blood pressure and implicated in cognitive functions. control of emotions and impulses.
The changes mainly affected men, less pronounced in women.
“This region of the brain that is important for emotional regulation may differ in people with depression,” the authors write. “The right side of the anterior cingulate cortex is involved in a wide variety of cognitive processes, including regulation of emotional conflict and optimistic bias.”
A similar relationship has been found in previous studies, but this is the first time it has been possible to demonstrate it on such a large sample. In addition, the researchers took into account not only information about people with clinically confirmed depression, but also the symptoms of this disease.
The scientists explain that the results of the study do not mention a causal relationship. Decreased anterior cingulate cortex can be both a cause and a consequence of depressive symptoms.
“The cingulate gyrus, which is part of the cingulate cortex, is the highest cortical part of the limbic system of the brain, which is responsible for the formation of the emotional background of all brain processes. Therefore, in a new study on a large sample of patients, researchers found that the brain with clinical depression, one of its main symptoms, It is not surprising that they found a decrease in the volume of the anterior part of this gyrus in its right hemisphere, only a violation of the emotional sphere, ”said a neurophysiologist, MV Lomonosov Professor Alexander Kaplan, head of the Neurophysiology Laboratory of the Biology Faculty of Lomonosov Moscow State University. remains a secret.
Usually, a functional decrease in the volume of the brain structure occurs due to a significant decrease in the number of neural connections between neurons.
This occurs when the function of this construct becomes overly specialized and the variable range of its states decreases. Kaplan explains that some areas of the cortex of grandmaster-level chess players, for example, become thinner. – It is possible that being psychologically “stuck” in some traumatic conditions of life leads to similar structural changes in the anterior cingulate gyrus, which translates the initially mild depressive state into a stable clinical form. Why only men when women all over the world are two to three times more likely to be depressed in their lifetime? Perhaps this is due to the initial hormonal differences between men and women, which can increase or slow down the development of structural changes in the cingulate gyrus, ”says the scientist.
Features of the structure of the brain are indeed associated with the risk of developing depression, but conclusions should not be drawn based only on the size of one region, says Olga Sysoeva, a leading researcher of the Russian Institute of Higher Nervous Activity and Neurophysiology. Academy of Sciences, candidate of psychological sciences Olga Sysoeva noted in a conversation with socialbites.ca.
“To speak of one or two structures is an oversimplification. For example, decreased production of the same serotonin affects the entire functioning of the brain in general. There are certain patterns in which some areas of the brain are involved a little more and others a little less, but overall the brain is complex and works within a system,” he explained. – The neocortex (main part of the human cerebral cortex), especially the amygdala, is connected to many areas with the anterior cortex, and with depression these connections are weakened. It turns out that a person has impaired information processing, control, participation in emotions. Symptoms may develop after taking certain medications. Other authors have shown that the risk of age-related depression increases with age, which may be associated with a reduction in brain volumes.
“Of course, depression affects many mental functions, particularly in its clinical expression, which indirectly indicates the presence of structural changes in many brain formations. In particular, a meta-analysis of neuroimaging data in major depression, including the orbitofrontal cortex and rectus gyrus of depressed patients, compared with controls. shows an increase in the volume of the basal ganglia, thalamus, hippocampus, and frontal lobe,” Kaplan adds.
In addition, it is often problematic to distinguish any predominant factor in the development of depression—and that features of the brain, certain genes, and life conditions all contribute. All these factors mutually affect each other and each can play a decisive role.
“There is a genetic factor in depressive disorders. The expression of genes associated with susceptibility to depression may change under the influence of external conditions. For example, dysfunction of the gene responsible for serotonin production has been associated with an increased risk of depression at certain exposures.
So, if you had a lot of childhood stressors and also had certain genetic traits, your risk of depression goes up.
The protein SERT, a serotonin transporter, is located at the cingulate cortex junction to the amygdala. So if a person has a particular genotype, this link is less. It can be argued that factors influencing the size and connectivity of the cingulate cortex with the amygdala lead to less resistance to external events that subsequently trigger depression,” explains Sysoeva.
Most of the research on the relationship of brain structure to the risk of developing depression or other diseases is relatively comparative, revealing differences between different groups of people. However, Sysoeva said that in the future there is a chance that comprehensive examinations, including MRI of the brain, will make it possible to reliably assess the risks for an individual patient.
“Man is a very complex system and the brain is always in interaction with external factors. In medicine, we are moving towards the fact that a person will be considered a whole organism with its own individual characteristics. According to certain patterns, it will be possible to determine whether the patient has a tendency to depression, what type of depression, and which therapy the person will respond best to. There are studies that take into account how the size and centers of the cingulate cortex respond to drugs, especially selective serotonin reuptake inhibitors. And it turned out that those with a larger cingulate cortex responded better to treatment. With 100% accuracy, I think it would never be possible to draw conclusions, but attributing people to certain groups is quite realistic. It is difficult, but some estimates based on the size of brain regions might be good if other factors are taken into account,” says Sysoeva.
Kaplan says it’s currently unlikely, even with fMRI, to identify a person’s susceptibility to depression at an early age, especially before puberty. For adults, the presence of morphometric manifestations of clinical depression, such as in the case of a decrease in the volume of the anterior cingulate gyrus, may be the basis for an unfavorable prognosis. However, the scientist concludes that the probability of this prediction coming true may not be high enough for the patient to bother himself with this prediction.