We know that stress can contribute to heart attacks and stroke, but exactly how remains an open question. Now for the first time in humans, researchers have tied that relationship to a specific part of the brain. In a study published in The Lancet, a team at Harvard Medical School found that increased activity in the amygdala is associated with higher risk of heart attack and stroke.
It was already known that people with post-traumatic stress disorder, anxiety and depression show increased function in the amygdala, a brain structure that plays a key role in generating sympathetic nervous system responses to emotional stressors. The Harvard researchers took a closer look at the relationship between stimulation of the amygdala and the development of cardiovascular events. Among the nearly 300 individuals observed for about 3.5 years, those with heightened amygdala activity experienced more events such as stroke and heart attack than those with lower levels of activity.
They found that these individuals also experienced elevated bone marrow activity and blood vessel inflammation, suggesting a possible explanation for the observed cardiovascular events. When bone marrow is overactive, this results in the increased production of white blood cells, an inflammatory response which can spur the development of plaques that clog blood vessels. The resting activity levels in the amygdala predicted cardiovascular disease independently of other known risk factors. The new findings point to avenues for future research to understand the impact of stress through both the sympathetic nervous system and inflammation.