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Stressed Out? Scientists May Have a Clue


Have you ever wondered why some people become more stressed out over an incident or event than others do? Do you tend to be more susceptible to stress than other people? Scientists have uncovered some clues as to why this may be so.

Mice are typically used in stress studies, and this new study is no exception. Scientists at University of Texas Southwestern Medical Center examined the brain cells of two groups of mice to determine how they responded to stress. Several weeks after they were exposed to a stressful event, investigators noted the mice that were more stressed out had enhanced neurogenesis, a process by which new nerve cells are produced in the brain.

Specifically, the new brain cells in the overly stressed mice survived longer than those produced by mice that were more capable of dealing with stress. These new cells were found in the hippocampus, an area of the brain associated with memory. This study is the first to link the memory of a stressful event or experience with neurogenesis in the hippocampus, according to Dr. Amelia Eisch, associate professor of psychiatry at UT Southwestern and a co-author of the study.

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This finding led the scientists to investigate what would happen if they prevented neurogenesis in both groups of mice. The result: the mice that had previously been stressed out became more resilient. Dr. Eisch noted that “This work shows that there is a period of time during which it may be possible to alter memories relevant to a social situation by manipulating adult-generated nerve cells in the brain.”

How does a stressed out mouse act? Research has shown that mice that are susceptible to stress clearly display social avoidance and depressive-like behavior, which is why these animals are typically used in studies of stress and depression. It is hoped that as scientists come to understand how the brain works in mice, it will lead to a better understanding of the human brain and behavior.

It is well accepted that stress is a cause or contributing factor in dozens of illnesses and diseases, including but not limited to asthma, heart disease, obesity, high blood pressure, insomnia, headache, gastrointestinal disorders, depression, and stroke.

It will likely be a while before scientists understand why some mice—and humans—are more likely to become stressed out than others, but this study brings them one step closer. Dr. Eisch notes that additional studies will look at which genes have a role in enhanced neurogenesis observed in mice susceptible to stress, and hopefully one day what they discover will prove helpful in understanding why we humans become so stressed out.

UT Southwestern Medical Center