Electrical Pattern in Brain May Help Predict Stress Response
Stress Frequently Precedes Mental Illness
Chronic stress or single instances of severe stress can give rise to depression, anxiety, post-traumatic stress disorder and various other mental disorders. However, while the connection between stress and psychiatric illness is well recognized, there are still many questions about the relationship that need to be uncovered.
The biggest question is exactly why similarly stressful situations affect some people more strongly than others. Some people facing chronic or traumatic stress have difficulty coping, and develop symptoms of mental illness. Others respond much better to stressful situations and do not develop symptoms of chronic psychiatric illness.
Differences Go Beyond Genetics
Genes are known to play a large role in determining how people respond to stress, but they are not the only factor. Research has found that even identical twins—who share identical genes—may respond differently to stress. Newer research is digging further into individual brain activity to find the sources of these differences.
New research published in Nature Communications in July 2014 may provide a clue. This research, which was conducted at the Duke University Medical Center, identified an electrical pattern in the brains of mice that appears to predict how they will respond to stressful stimuli.
Specifically, the research examined the reaction between the amygdala, which contributes to the instinctive “fight-or-flight” response, and the prefrontal cortex, which suppresses the brain’s emotional reactions in favor of planning and other higher-level functions. The relationship between these two parts of the brain is found in both mice and humans.
Early Responses Predict Chronic Stress Reactions
Led by assistant professor of psychiatry and behavioral sciences, Kafui Dzirasa, the Duke team examined the mice’s responses to the first introduction of stress as well as chronic exposure to stress.
They found that the way the mice responded to stress was dependent on how effectively their prefrontal cortex managed the emotional reactions of their amygdala. Perhaps more significantly, they found that the amygdala-prefrontal cortex interplay seen during the first exposure to stress predicted the interplay between these two parts of the brain after chronic stress exposure.
The researchers found that mice that exhibited poor reactions to chronic stress exhibited an electronic brain signature in the form of greater activity along the amygdala-prefrontal cortex circuit when they were first exposed to stress.
This “signature” could help scientists identify those people who are particularly vulnerable to chronic or severe stress before that stress occurs. This could allow vulnerable individuals to receive treatment or some other form of intervention before exposure to stress can give rise to mental illness, substance use disorders or simply difficulty coping while the stress remains present.
Researchers Hope to Treat Stress Directly
Dzirasa and his fellow researchers even hope that a better understanding of the electrical signatures of poor stress responses will eventually allow for the direct treatment of stress. They believe it is possible that understanding the electrical interplay between the parts of the brain that respond to stress could allow them to prevent symptoms of stress from appearing, even when external stressors are present.
The scientists also believe that there is much more to discover about the interplay between the circuit patterns they identified and the genetic risk factors that also contribute to mental illness. Although research is identifying more and more genetic markers for different psychiatric illnesses, it is also clear that these markers alone do not clearly predict illness. Most likely, genetic risk factors and stress experiences work together to trigger psychiatric illness.