Brain development is encoded in the set of genes we are born with, our chromosomes.
Chromosomes are composed of 50% DNA and 50 % protein molecules carrying epigenetic marks. The epigenome, these chemical markers and switches are attached to the DNA with the role of genetic regulation, activating the expression of the genes or shutting them off. The embryo is a mere bundle of identical stem cells. Through cell division, each cell inherits the same genes but with a different epigenome. The formations of the brain (and each body tissue) are due to a particular combination of silent and active genes.
Both the DNA and the epigenome are critical to the healthy development of the embryo and eventually to the human born. Up until recently, researchers believed the epigenetic pattern is determined during early stages of fetal development. They discovered chemicals that cause epigenetic interferences in the embryo, for example folate for preventing spina bifida, a spinal column malformation disease; or fetal alcohol syndrome, which results in behavioral problems and low IQ.
Pregnancy is still an extremely critical period, but new studies have discovered the epigenetic pattern in the brain can continue to change after birth. Childhood and life experiences can physically rearrange the epigenome, and change how the brain cells work.
Depression is possibly an epigenetic disease
One study found depression in mice changed the epigenome pattern in part of the brain called nucleus accumbens. It’s no coincidence since the nucleus accumbens plays an important role in the brain’s reward system, determining how much we value things and get pleasure from them. In another study the researchers found these same epigenetic pattern changes in the same brain region, while examining brains of human cadavers, who at some point in there lifetime were diagnosed as suffering from depression.
One form of epigenetics is seen in changes to the histone code, coiled around the DNA. These changes cause interferences to the chemical signals for activating the gene, thus shutting off its expression. Animal studies have discovered treatment with a drug, which loosens this coiling around the DNA. By allowing the cells to reconnect with the genes the researchers eliminated many symptoms of depression.
The implications of this new research raise the possibility to alter the epigenetic pattern through medication to relieve mental patients of their debilitating symptoms as depression and severe anxiety.