You may have heard that stress and anxiety shrinks your brain. I'd like to be the voice of an informed contrarian and say that this isn't true. But studies suggest that although stress doesn't exactly reduce the brain to the size of a dried-up walnut, it does seem to cause structural changes, including shrinkage in some regions.
We have known for some time that stress increases the likelihood and severity of anxiety, and boosts the risk of bodily disorders like high blood pressure and heart problems. But it is also linked to higher risk for mental conditions such as depression. And prolonged stress may even decrease the size of certain brain areas.
One large study, published in Biological Psychiatry in 2012, found that several neural regions in people who had undergone chronic stress and "adverse life events," like a loss of a loved one, were smaller compared with people who hadn't been having a hard time. Specifically, stress and adversity were associated with smaller volumes in the prefrontal cortex, insula and anterior cingulate cortex, regions that regulate emotion, self-control, and top-down cognitive processing, the researchers found.
More recent research done in the past year has elaborated upon the way that adversity and anxiety changes the brain. In a study done at the University of California-Berkeley, researchers looked at one part of the brain, the hippocampus, and found that chronic stress leads to the generation of "more myelin-producing cells and fewer neurons than normal." Myelin is a material that coats axons, or connections between nerve cells, generally known as white matter. By tampering with this balance, chronic stress may increase white matter in some cases while decreasing the gray matter composed of neurons and supportive glial cells.
The study suggests that stress could decrease the gray matter in the hippocampus, the region crucial in memory and learning, while increasing the amount of white matter, perhaps making it more connected to the amygdala, the part of the brain that helps govern the body's fight-or-flight response and is implicated in anxiety disorders.
"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," said Berkeley researcher Daniela Kaufer in a statement.
This theory goes hand-in-hand with research showing that stress tampers with brain's ability to be neuroplastic and able to produce new neurons and connections. A hormone released during stress called cortisol can also inhibit the formation of cells and reduces the size of the hippocampus.On the other hand, cortisol is linked with an increase in the activity and size of the amygdala.
Luckily, various behaviors can help reverse these changes. Exercise has been shown to increase connectivity between brain regions, a linkage which is interfered with by stress. Mindfulness practices could also help the brain spring back. One study by researchers at Massachusetts General Hospital found that those who practiced mindfulness meditation for eight weeks saw a growth and thickening of gray matter in the prefrontal cortex, the region that seems to shrink in the face of chronic stress. Moreover, meditation was linked to increases in hippocampal volume, and decreases in the size of the fight-or-flight-minded amygdala.
These findings suggest that exercise and meditation are the antidote to stress, even when it comes to brain volume; so if you find yourself chronically stressed, get moving. It can't hurt.
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