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STUDY: Heart Rate and Immunity
JOURNAL: Brain, Behavior, and Immunity 2002;16:411-420
AUTHORS: Dr. Noha H. Farag
ABSTRACT: The temporary rise in blood pressure that accompanies a stressful situation can be caused by an increase in heart rate and a stiffening of blood vessels. Now, researchers report that people who are more likely to experience a rapid heart rate may also be more prone to problems with immunity.
COMMENTARY: The findings may help to explain why chronic stress can lower immunity and make some people more prone to inflammatory diseases such as atherosclerosis.
The researchers took blood samples and monitored the heart rates of 49 healthy adults who were asked to give a speech in response to two stressful scenarios. First, study volunteers talked their way out of shoplifting accusations and then confronted a car dealer for failing to honor a warranty. The volunteers were categorized as "cardiac" or "vascular" reactors. For cardiac reactors, the main stress response was an increase in the heart rate, while vascular reactors showed increased blood vessel stiffness.
The cardiac reactors showed changes in immune system activity not seen among those in the other group. Specifically, there was an increase in the numbers of certain immune cells suggesting that cardiac reactors have a greater immunological response to stress.
These cells, known as lymphocytes, are involved in the "fight or flight" response in which certain hormone levels rise to prepare the body to confront a physical or emotional challenge.
Cardiac and vascular reactors can be differentiated on the basis of immunological changes.
Interestingly, it is only cardiac responders that show a significant redistribution of lymphocytes in response to stress.