Stress-Induced Brain Abnormalities May Trigger Mental Illness
It’s pretty well known that mental illness has both a genetic and an environmental component. Some people are born predisposed to anxiety, depression and other disorders, while others develop those problems in response to hardship or trauma.
Past research has shown that people with stress-related mental illnesses have noticeable brain abnormalities. Now, in a study published in the journal Molecular Psychiatry this week, researchers from the University of California, Berkeley, explain how chronic stress may cause lasting changes in the brain that leave people vulnerable to anxiety and other mood disorders. These findings could help in the development of new kinds of therapies to reduce risk of mental illness after stressful or traumatic experiences.
Gray Matter vs. White Matter
Patients with stress-caused mental illness, such as PTSD, are known to have more white matter and less gray matter in their brains than those who do not have such disorders. A quick layman’s explanation of gray and white matter:
- Gray matter: mainly made up of neurons, which are the cells responsible for storing and processing information, as well as supporting cells called glia
- White matter: composed of axons, which build the network of fibers that interconnect neurons. A white, fatty myelin sheath surrounds the axons (giving “white matter” its name) and causes electrical signals to move faster from cell to cell.
What the Berkeley researchers found is that chronic stress causes an excess of myelin in the hippocampus by creating more myelin-producing cells and fewer neurons, upsetting balance and communication in the brain. The hippocampus is the part of the brain responsible for regulating emotion and memory, and it is known to play a role in a number of emotional disorders.
These findings may demonstrate how brain connectivity is different in people with disorders such as PTSD. Kaufer explained that it’s possible that PTSD sufferers have a stronger connection between the hippocampus and the amygdala, which is responsible for the stress response, and a weaker connection between the hippocampus and the prefrontal cortex, which keeps our responses in check.
“You can imagine that if your amygdala and hippocampus are better connected, that could mean that your fear responses are much quicker, which is something you see in stress survivors,” Kaufer said. “On the other hand, if your connections are not so good to the prefrontal cortex, your ability to shut down responses is impaired.”
Insight for the Future
Kaufer is now testing this hypothesis in PTSD patients, and she’s also working to determine how chronic stress early in life may make people less resilient as they get older.
“Our findings could provide insight into how white matter is changing in conditions such as schizophrenia, autism, depression, suicide, ADHD and PTSD,” she said.