UK scientists have shown that the brain area responsible for learning, memory and emotion may play a key role in putting the heart under strain in times of stress. They showed how signals from these areas destabilized the cardiac muscle of someone who already had heart disease and how they could lead to potentially fatal abnormalities in the heart's rhythms.
It has been previously thought that more primitive parts of the brain caused increased activity in the heart when under stress.

Researchers from the University College London and the Brighton and Sussex Medical School decided to study 10 patients with specific heart conditions. They measured the electrical changes at the surface of the skull while patients were performing a stressful task. They were counting backwards in sevens.

The researchers noticed that activity in the 'higher level' regions of the brain, such as the cortex closely reflected the response measured in the heart. They also spotted that a "feedback loop" was established, with these centres reacting to information being fed back from the heart by pumping out more signals to increase activity. These actions destabilized the heart muscle and opened a door to the possibility of abnormal and potentially dangerous rhythms, which could cause sudden death in vulnerable patients.

It has been previously known that stress could increase the risk of sudden death through cardiac arrest and that the brain areas responsible for regulating heart function can be unbalanced by stress. This study revealed that it was cerebral cortex might be having a significant role in these events by becoming involved in a vicious circle.
These findings could enable doctors to identify patients whose hearts are more likely to have an adverse response to stress.