How Chronic Stress Unbalances Your Brain

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The findings of researchers do not always provide quick answers to health problems, but they often remind us of the significance of our daily lifestyle choices.

For instance, recent studies about how stress affects the brain remind us of our body’s need for relaxation.

Research completed at the University of California in Berkeley revealed specific alternations that occur in a stressed brain. These changes could explain the link between chronic stress and our vulnerability to mental health problems.

The Brain on Stress

It seems that chronic stress disturbs the brain’s healthy balance between white matter and gray matter:

  • Gray matter consists largely of neuron cells that process and retain information, and supportive glial cells.
  • Our brain’s white matter is made of a network of nerve fibers or axons. The axon network interconnects our neurons. It is called white matter because of the fatty white myelin sheath that coats the axons, facilitating a speedy transfer of brain signals.

The research team found that chronic stress triggers the increased production of myelin-generating cells and a decreased production of neurons. This causes the shift in the white and gray matter ratio, altering communication patterns between areas of the brain.

Stress and Stem Cells

The Berkeley scientists focused their study on the brain’s hippocampus and discovered that chronic stress affects the development of certain stem cells there:

  1. Under stress, stem cells that normally mature into neurons or astrocytes (a type of glial cell) grow into cells called oligodendrocytes.
  2. Oligodendrocytes (also a type of glial) manufacture the myelin sheath that surrounds the axon network; they also help create the synapses (sites) where one neuron communicates with another, and influence the axon growth pathways that form synapses.

So, under duress, fewer neuron cells (gray matter) are created, and our white matter increases. Since the hippocampus is involved with memory and emotional regulation, a disruption in its communication mechanism may trigger, or play a part, in a variety of emotional disorders such as PTSD.

PTSD Theory

The researchers hypothesize that an individual could develop strong signal connectivity between the hippocampus and the brain’s fight or flight organ—the amygdala—and develop too few connections between the hippocampus and the decision making prefrontal cortex. This imbalance could account for PTSD symptoms:

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.

On the other hand, if your connections are not so good to the prefrontal cortex, your ability to shut down responses is impaired. So, when you are in a stressful situation, the inhibitory pathways from the prefrontal cortex telling you not to get stressed don’t work as well as the amygdala shouting to the hippocampus...you have a much bigger response than you should. ~ Daniela Kaufer, researcher

Source: News Center, Berkeley

 
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