What are the symptoms of depression?

As our living conditions gradually improve and as the pressure of life around us gradually increases, most people grow up in extremely stressful conditions. However, such excessive pressure will make us tired, and the incidence of some diseases will gradually increase. Therefore, we must pay attention to living a happy life in our lives. So let’s understand what the symptoms of depression are!

1. Causes and related factors

To date, the cause of depression is not very clear, but it is certain that many biological, psychological and social environmental factors are involved in the pathogenesis of depression. Biological factors mainly involve genetics, neurochemistry, neuroendocrine, neural regeneration and other aspects; the psychological susceptibility factors closely related to depression are pre-morbid personality traits, such as depressive temperament. Encountering stressful life events in adulthood is an important trigger for the onset of clinically significant depressive episodes. However, these factors do not act alone, and the interaction between genetics and the environment or stress factors, as well as the timing of this interaction, have an important impact on the occurrence of depression.

2. Genetics

Studies have shown that the prevalence of depression in relatives of patients is 10 to 30 times higher than that in ordinary families, and the closer the blood relationship, the higher the prevalence: 14% for parents, children, siblings, 4.8% for uncles, aunts, grandparents, etc., and 3.6% for cousins. For monozygotic twins, it is 46%, and for dizygotic twins, it is 20%. [3] From this we can see that depression is closely related to genetics.

It has been found that a total of 19 regions on chromosomes 1p, 1q, 2q, 4q, 5q, 8q, 10p, 10q, 11p, 11q, 15q, 18q, 19p and Xq are significantly linked to major depressive disorder, of which 10 regions are strongly linked. [4] Generally speaking, the physiological structures associated with depression are often also associated with genes related to depression. For example, CRHR1, FKBP5, etc. (related to the HPA axis), BDNF (Val66Met), etc. (related to brain-derived neurotrophic factor (BDNF)), etc.

Epigenetics

DNA methylation is a relatively stable gene expression regulation mode in postmitotic cells and may be involved in long-term changes in gene expression in response to stress-induced abnormalities. People have found that some depression-related factors are related to the methylation of HPA axis-related genes, the prefrontal cortex p11 promoter region, the glial cell-derived neurotrophic factor promoter region, etc.; in the promoter region involved in HPA response and antidepressant treatment, the methylation levels of certain parts have changed. For example, depressive-like symptoms induced by chronic social failure stress are accompanied by upregulation of corticotropin-releasing factor (CRF) and cause a decrease in DNA methylation in the promoter region of the CRF gene, an effect that can be reversed by imipramine.