Stress makes our brain more susceptible to mental illness

Experts already know that people suffering from chronic stress are prone to experiencing mental health problems - such as anxiety and mood disorders - later in life.

The human brain is made up of "gray matter" and "white matter" and scientists have noticed that the proportions of white versus gray matter are different in people with stress illnesses, compared with other people. White matter gets its name from the white, fatty "sheath" of myelin coating it - the electrically insulating layer that forms around nerves and accelerates the transmission of electrical signals between cells. The new study focused on cells in the brain that produce myelin - the electrically insulating layer that forms around nerves.

The researchers found that an excess of white matter is found in some areas of the brain in people who experience chronic stress. It seems that the experience of chronic stress causes more myelin-producing cells to be generated, with fewer neurons than normal. The consequence of this is that the excess of myelin causes the "delicate balance" of the brain to be disrupted, with communication between brain cells slipping out of their normal timing.

People with stress undergo changes in brain connectivity also. Post traumatic stress disorder patients might have weaker connectivity between the hippocampus and the prefrontal cortex, which moderates our responses. In them, the ability to shut down responses will be impaired.