When someone is under chronic stress, it begins to negatively affect his or her physical and mental health. The body’s stress response was not made to be continuously engaged. Many people encounter stress from multiple sources, including work; money, health, and relationship worries; and media overload.
With so many sources of stress, it is difficult to find time to relax and disengage. This is why stress is one of the biggest health problems facing people today.
Chronic stress increases the risk of developing health problems including obesity, diabetes, heart disease, cancer, and a weakened immune system. Chronic stress also affects a person’s mental health. Many studies show a correlation between stress and the development of mood disorders such as anxiety disorders and depression.
According to the American Psychological Association’s latest stress survey, 66 percent of people regularly experience physical symptoms of stress, and 63 percent experience psychological symptoms.
Link between Stress & Mental Health
Although many studies have shown a link between stress and mental health problems, the reason behind this connection has remained unclear. Recent research from the University of California, Berkeley, has discovered new insight into why stress can be so detrimental to a person’s psyche.
Previous research has found physical differences in the brains of people with stress disorders, such as post-traumatic stress disorder (PTSD), and those without. One of the main distinctions is that the ratio of the brain’s white matter to gray matter is higher in those with stress-related mental disorders compared to those without.
People who experience chronic stress have more white matter in some areas of the brain. The UC Berkeley study wanted to find out the underlying reason for this alteration in the brain composition.
Gray matter in the brain is composed mainly of two types of cells: neurons, which process and store information, and glia, cells that support the neurons.
White matter mostly is composed of axons, which form a network of fibers to connect the neurons. It is called white matter because of the white, fatty “sheath” of myelin coating that insulates the nerves and accelerates the transmission of the signals between the cells.
For this study, the researchers focused on the cells that produce myelin in the brain to see if they could find a connection between stress and the proportion of gray brain matter to white.
The researchers performed a series of experiments on adult rats, focusing on the hippocampus region of the brain (which regulates memory and emotions). During the experiments, they found the neural stem cells behaved differently than expected. Prior to this study, the general belief was that these stem cells would only become neurons or astrocyte cells, a type of glial cell. However, under stress, these cells became another type of glial cells, oligodendrocyte, which are the myelin-producing cells. These cells also help form the synapses, which are the communication tools that allow nerve cells to exchange information.
Thus, chronic stress causes more myelin-producing cells and fewer neurons. This disrupts the balance in the brain, causing communication in the brain cells to lose its normal timing, which could lead to problems.
Stress Disorders & Brain Connectivity
This might mean that people with stress disorders, such as PTSD, have alterations in their brain connectivity. This might lead to a stronger connection between the hippocampus and the amygdala (the area that processes the fight-or-flight response). It might also cause weaker connectivity between the hippocampus and the prefrontal cortex (the area that moderates the responses).
If the amygdala and hippocampus have a stronger connection, the response to fear is more rapid. If the connection between the prefrontal cortex and the hippocampus is weaker, then the ability to calm down and shut off the stress response is impaired. Therefore, in a stressful situation, a person with this imbalance will have a stronger response with a limited ability to shut down that response.
This study shows that the oligodendrocyte cells might play a key role in long-term changes to the brain that could lead to mental health problems. The researchers also believe that the stem cells which, due to chronic stress, are becoming myelin-producing cells rather than neurons, affect cognitive function, because it is the neurons that process and transmit the electrical information necessary for learning and memory skills.
More research is required to verify these findings, including studying humans rather than rats, which the researchers have planned. However, this study provides important insight into why chronic stress affects the brain and mental health, and how early intervention can help prevent the development of certain mental health problems.