Studies have shown chronic stress can raise the chance to develop mental illnesses and mood disorders. A new study conducted by the scientists from the University of California, Berkeley, now reveals how is this possible.
Delicate balance between gray and white
The brain contains two types of cells, to put it simply. There is “gray matter” and “white matter” and the balance between the two is destroyed in people suffering from post-traumatic stress. While the “gray matter” is related to intelligence, the “white matter” level is linked to myelin. The cells forming the “white matter” are coated in a layer of myelin, which is conducting the electrical impulses between the brain cells.
Too much white
Excessive “white matter” is linked to mental disorders because the normal rhythm of response to external stimuli is disrupted. People exposed to chronic stress experience an outburst of myelin cells, at the expense of neurons.
As a result, the normal timing of communication between brain cells is affected.
Rats proved the point
Researchers used rats to prove their theory and to see how the imbalance is caused. The stem cells in the hippocampus area of a rat’s brain develop only into astrocytes, under normal conditions. But, the stem cells of adult rats exposed to stressful conditions developed into oligodendrocytes – cells producing myelin. These cells are also connected to synapses’ development. Synapses are the structures which help cells communicate with each other.
Better connectivity and poor response to stimuli
Researchers concluded that people who experience post-traumatic stress disorders experience changes in brain connectivity as well. The amount of “white matter” increases and the link between the amygdala and hippocampus became stronger. As the link between the frontal cortex and the hippocampus grows weaker, the body’s answers to stress are more violent.
In other words, all these connections will tell your brain is time to over-react when you are faced with stressful situations, as there is nothing to inhibit the reaction, how it would be normal.
The last discovery made by the scientists is related to the memory loss and decreased learning ability which are found in people with post-traumatic stress disorders. Because stem cells develop into “white matter”, the “gray matter” or the intelligent cells in the brain will decrease in number as they grow old and die. The person will then experience learning issues and memory loss.
Researchers will conduct further studies and will also analyze the possibility to predict the appearance of stress disorders based on a scan of the brain.
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