Stress triggers the release of cortisol, also known as the stress hormone. Having some cortisol in your body isn't a bad thing. This hormone can help lower blood pressure, sugar levels, and inflammation. Moreover, brief stressful events can stimulate the formation of new nerve cells, which consequently improves mental performance. However, too much stress doesn't have these same effects. Instead, prolonged stress leads to elevated cortisol levels that can take a toll on your brain, specifically on gray matter.
Brain tissue can be divided into the gray matter that's composed of brain cells and the white matter, which contains the filaments that extend from the cells. The amount of gray matter found in specific regions of the brain is directly associated with various abilities and skills. Those who are constantly stressed tend to have less gray matter in the hippocampus and prefrontal cortex. The hippocampus is the part of the brain involved in learning and memory. Meanwhile, the prefrontal cortex is involved in the communication between different brain regions, which is important for regulating thoughts, emotions, and actions.
There's proof that the volume of the gray matter does decrease due to chronic stress. In a recent study from the journal Neurology, researchers looked at the cortisol levels, memory, thinking skills, and brain volume of 2,231 healthy middle-aged participants. The results showed that participants, especially women, with high cortisol levels did poorly on memory and cognitive tests. They also appeared to have a smaller brain volume.
“Slightly lower brain volumes and memory performance of the magnitude seen in this study are associated with a higher risk of dementia 10 to 20 years later,” said Dr. Sudha Seshadri, director of the Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases at the University of Texas (UT) Health San Antonio and one of the authors of the study.
A similar brain "shrinkage" phenomenon was observed by Dr. Monica Starkman from the University of Michigan Medical School in patients with Cushing disease. This rare condition is characterized by excess levels of cortisol in the body. According to Dr. Starkman, the hippocampus of patients who suffer from this disease was smaller compared to those in healthy normal subjects. Fortunately, this study also showed that when cortisol levels went down after treatment, the volume of their hippocampus increased along with their learning scores.
Overall, these studies suggest that chronic stress can have adverse effects on the volume of gray matter. Consequently, this can lead to problems with regards to different brain functions. (Related: Stress found to affect the brain’s speech center: Language patterns reveal a biological response to stress.)
People who are under a lot of stress tend to experience the following health problems as well: