DNA and Depression
Individuals who have an immediate family member with clinical depression are four to five times more likely to develop depression. Even though there are nearly 178 gene-variants responsible for depression; scientists may have isolated a certain area in the brain and genes that is responsible for pleasure. These genes can also shut-down, or mutate and cause depression. In the future, genetic therapy might be able to repair or change the brain function by adding a missing brain protein p11 to this specific area of the brain.
Small chemical groups can cause protein complexes to bind to histones and these can control genetic activity. The researchers have studied in detail a molecular complex called PRC2 which can attach small methyl groups to the histones. Protective complexes can bind to the histones when this marker is present and the genes are turned off. Their new results show that the protective complexes are lost and selected genes turned on when cells are exposed to external stress factors. This influences how the brain responds to stress and plays a key role in depression. These genetic mutations preclude certain individuals from producing enough neuropeptide Y; and are prone to have more intense negative emotional responses when subjected to stressful situations.
Further Studies into the Genetic Link to Depression
Another study in 2020 concluded that p11 affects the initial release of the stress hormone cortisol in mice by modulating the activity of specific neurons in the brain area hypothalamus. Through a completely different signalling pathway originating in the brain-stem, p11 also affects the release of two other stress hormones, adrenaline and noradrenaline. In addition, the tests showed that mice with p11 deficiency react more strongly to stress, with a higher heart rate and more signs of anxiety, compared to mice with normal p11 levels.
As a sidebar, cortisol is the most researched stress hormone related to depression. Evidence suggests that nearly half of patients presenting with major depression demonstrate a hyper-secretion of cortisol. Though there seems to be conflicting opinions regarding whether cortisol causes depression or vice versa, whether depression influences the release of cortisol.
When the fight or flight response is activated due to psychological stress, and there is no physical release of hormones, cortisol levels may build up, affecting mental wellness. In individuals who are not depressed, cortisol levels in the bloodstream peak in the morning after waking up, and decrease as the day continues. In depressed individuals cortisol does not decrease throughout the day, and instead remains elevated. It has been estimated that heightened cortisol levels in the afternoon and evening occur approximately half of depressed individuals. Some researchers have suggested that these elevated levels affect the successful transmission of the neurotransmitter serotonin, which has been associated with mood, therefore triggering depressive symptoms.
The interesting aspects of these findings are that stress can alter our body chemistry with regards to changing our DNA. Also, this discovery could possibly lead to genetic engineering and actually provide a cure for depression in the future. Read more from the following article Depression and DNA
This post was updated November 21, 2022