Scientists at Laval University have discovered how major depression affects women and men differently as well as a blood marker that might help better diagnose and treat the disease.
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“There are important differences between men and women in depression,” said study leader Caroline Ménard, professor at the Faculty of Medicine at Laval University and researcher at the CERVO Research Center. In women, this disease is twice as common, the symptoms are different and the response to antidepressants is not the same as in men. Our work aimed to identify the causes of these differences. ”
Thus, the study, published Monday in the journal Nature Communications, analyzed the brains of people with depression at the time of their death revealed the presence of alterations located in different brain regions depending on gender. Ms. Ménard’s team was also successful in identifying a potential biomarker for depression in women.
Mouse study
In a previous study, Caroline Ménard’s team had shown that prolonged social stress in male mice reduced the tightness of the blood-brain barrier that separates the brain and the peripheral blood circulation. These changes, attributable to the loss of the claudin-5 protein, were manifested in a region of the brain involved in emotional control and reward. The researchers had made the same observations by examining the brains of men suffering from depression at the time of their death.
By repeating this experiment in female mice, Professor Ménard and her collaborators observed that the alterations in the brain barrier caused by the loss of the claudin-5 protein were localized in the prefrontal cortex. They came to the same conclusion by examining the brains of women with depression at the time of their death.
In men, however, this barrier of the prefrontal cortex was not affected. “The prefrontal cortex is involved in regulating mood, but also in anxiety and self-perception,” said Mme Ménard.
This region is not altered in male mice under chronic stress or in men with depression. These results suggest that chronic stress alters the brain barrier differently depending on gender.
New blood marker
Furthering their investigation, the researchers discovered a blood marker linked to the health of the brain barrier. This marker, soluble E-selectin, is an inflammatory molecule whose level is higher in the blood of stressed female mice. It is also present in blood samples from women with depression, but not from men.
“Even today, the diagnosis of depression is made by means of questionnaires”, noted Caroline Ménard.
His group is the first to show the importance of neurovascular health in depression and to propose soluble E selectin as a biomarker for this disease. It might be used for screening and diagnosis of depression. “It might also be used to measure the effectiveness of existing treatments or treatments in development. Before getting there, however, clinical studies on large cohorts will have to be carried out to confirm their reliability, ”she continued.
