The relationship between stress, cardiovascular health, and the brain is complex. A new study uses brain imaging and computer-learning to uncover which individuals are most at risk of stress-related cardiovascular disease.
Psychological stress, as we are all aware, affects our physiological state. In a stressful situation, our body assumes that we are in imminent danger, and heart rate and blood pressure escalate in readiness for trouble, ready to fight or fly.
Although this reaction is designed to aid our survival in the wild, if the response is triggered often, it can harm cardiovascular health. However, not everyone responds in the same way, and people respond to psychological stressors to varying degrees. Some individuals are more likely to demonstrate sharp blood pressure spikes to psychological challenges than others.
Because this subsection of the population has an elevated risk of cardiovascular disease, grasping why they respond excessively could help science to understand the mechanism in more detail, and, in the future, help to curtail it.
Stress and the brain
Cardiovascular reactions to stress are generated and regulated by regions of the brain collectively referred to as "brain areas for visceral control." They include cell groups in the:
- prefrontal cortex, which has roles including complex planning and decision-making
- insula, which is linked to homeostasis, among other tasks
- hippocampus, which regulates emotion, memory, and the autonomic nervous system
- amygdala, which controls emotions
- thalamus, which has roles such as relaying sensory and motor information and regulating alertness
- hypothalamus, which helps to regulate metabolism and the autonomic nervous system
- periaqueductal gray, which is involved in pain modulation
- pons, which is involved in sleep, breathing, swallowing, and bladder control, among other things.
- medulla, which is responsible for autonomic responses
Activity throughout these regions (and others) orchestrates the physiological response to psychologically stressful events. Researchers believe that differences in the patterns of activity across the brain areas for visceral control might account for individual variation in stress-produced cardiovascular responses, and, therefore, stress-related cardiovascular risk.
Brain imaging the stress response
In an effort to glean a deeper understanding of the "brain-body link between stress and health," a group of researchers from the University of Pittsburgh in Pennsylvania set up an experiment based on brain imaging.
The team conducted mental stress tests on participants while they were in an MRI scanner. Participants were given negative feedback while carrying out a stressful, timed computer challenge. At the same time, blood pressure and heart rates were monitored.
In all, 157 men and 153 women aged 30 to 51 were included in the study. The results are published this week in the Journal of the American Heart Association.
As expected, the stressful test induced an increase in blood pressure and heart rate compared with the participants' baseline readings. Once the team had the brain scan data, they used machine-learning techniques to tease out the specific brain pattern that marked the size of an individual's physiological stress response.
They were able to successfully predict the size of each participant's cardiovascular response from the particular patterns of activity measured in their brain.
The brain areas that were most useful in predicting the size of the physiological stress reaction were those areas considered important in deciding whether information coming in from the senses signals a threat, which included many of the brain areas for visceral control mentioned earlier.
Stress' widespread action in the brain
Medical News Today recently spoke with lead study author Peter Gianaros, Ph.D. Describing the results, he said, "The most interesting finding is that it wasn't just a single brain area that predicted stress responding."
"In other words, there doesn't seem to be just one brain area for stress. Stress is more likely to involve multiple areas across the entire brain working together to change our physiology - it's basically the whole enchilada."
Although the findings cannot conclusively draw out cause and effect, the findings are a step forward in understanding the brain-body stress repose.
"This kind of work is proof of concept, but it does suggest that, in the future, brain imaging might be a useful tool to identify people who are at risk for heart disease or who might be more or less suited for different kinds of interventions, specifically those that might be aimed at reducing levels of stress," says Dr. Gianaros.
"It's the people who show the largest stress-related cardiovascular responses who are at the greatest risk for poor cardiovascular health and understanding the brain mechanisms for this may help to reduce their risk."
Peter Gianaros, Ph.D.
MNT asked Dr. Gianaros whether, in the far future, these kinds of studies might lead to ways in which the brain could be "retrained" to respond to stress differently. He believes that this could be a possibility much further down the line, but that "work on brain stimulation and neurofeedback is still in its infancy."
The interaction between mind, body, and physical health is receiving a great deal of attention at the moment, and Dr. Gianaros plans to continue his investigations. He told MNT that he and his team are currently "applying the same brain imaging methods to see if stress-related activity can predict changes in vascular risk factors over several years."