A new study aims to examine if a relationship exists between cardiovascular events and the activity of the amygdala, a structure located in the brain which is responsible for, among other things, the processing of emotions such as stress.
Stress is a phenomenon that many people have experienced, and which can take a significant toll on the body. For example, the link between stress and cardiovascular events, such as angina, myocardial infarction, or even heart failure, has been known for some time. However, until recently the specific pathway through which stress acts to bring about these results has been largely unknown due to a lack of investigation. Researchers know that the amygdala, a structure located in the brain, is responsible for processing of emotions, including stress, and therefore hypothesized that the activity of the amygdala would be able to predict a cardiovascular event. They also looked at hemopoietic activity (bone marrow activity) and arterial inflammation, as they also believed these to be factors in the pathway that leads to a cardiovascular event.
This study published in The Lancet looked at 293 individuals, all over the age of 30, who lived in the state of Massachusetts. All of these individuals were chosen because they had undergone a PET/CT scan during the period of January 1st 2005 and December 31st 2008, at Massachusetts General Hospital. These PET/CT scans were analyzed and used to provide baseline information on the activity of the amygdala, bone marrow, spleen, as well as arterial inflammation of these participants. In addition, all of the individuals had no history of cancer, or if they had, were in remission for the duration of at least a year at the time of the scan. Also, the researchers eliminated any individuals that had a history of cardiovascular disease, autoimmune disease, or an acute or chronic inflammatory disease.
After the results of the initial scan were analyzed, participants were monitored for a follow-up period that generally lasted for 3.7 years. Through analyzing the PET/CT scans, researchers determined that individuals whose amygdalas were more active at rest tended to suffer from cardiovascular events sooner than those individuals with less active amygdalas. In addition, researchers identified that the activity of the amygdala was correlated with the activity of both the bone marrow and arterial inflammation. From this, it can be said that bone marrow and arterial inflammation are significant mediators in the pathway between the amygdala and the experience of cardiovascular events. Overall, from these findings, researchers have determined that amygdalar activity predicts the likelihood of suffering from a cardiovascular event.
The findings of this study are interesting because this is the first time that research has demonstrated, in humans, that the likelihood of suffering from a cardiovascular event is linked to amygdalar activity. As a result of this, these findings have helped to shed light on the pathway that leads to cardiovascular events, and can, therefore, influence the actions taken to decrease the risk of suffering from these events. However, while these results are exciting, they must be taken with caution. This is because the study consisted of a fairly small sample size, which may lead to trouble in generalizing the results to the public. In addition, these results, while being consistent with causation, do not actually show causation. Therefore, even though amygdalar activity can predict cardiovascular events, at the moment we cannot say definitively that one causes the other. Further studies must be completed to prove causation.
Written By: Sonia Parmar, HBSc