Chronic stress has the ability to change a person’s brain in ways that can affect memory and lead to mental illness.

Research out of the University of California, Berkeley has determined that prolonged and excessive levels of stress hormones alter the structure of the brain by causing extra white matter to be produced. Abnormalities in white matter have been associated with various mental illnesses, such as depression bipolar disorder, schizophrenia, obsessive compulsive disorder, and post-traumatic stress disorder.

Stress hormones, such as cortisol, have been shown to play a role in the way that memories are stored and retrieved as well. The constant presence of stress hormones can cause white matter to build up in areas responsible for memory, such as the hippocampus. This white matter prevents neurons in the brain from communicating effectively, creating problems with memory at both the formative and recollective stages.

Research suggests that these types of memory problems can contribute to the development of post-traumatic stress disorder. According to a study published by the National Institutes of Health, concentrations of white matter in the brain can lead to a variety of mental health concerns.

Neuroscientists at the University of California, Berkeley, either injected mice with a stress hormone called corticosterone or fitted them with straight-jackets meant to induce stress by rendering them immobile for three hours each day for seven days. They found that those with elevated levels of stress were not able to produce oligodendrocytes, a substance that helps support communication between nerves.

Not only does chronic stress cause extra white matter production, which hinders neuronal communications, but the brain appears to also be unable to insulate the neurons, further hindering the transmission of electric impulses so necessary to brain function. This discovery adds possibilities to the approaches taken to treat certain types of mental illnesses.