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Anxiety is a fear whose cause is difficult to discern. A new American study has just shown that increased heart rate can create anxiety. The results could thus clarify certain gray areas on the treatment of chronic anxiety disorders.
Emotions, such as fear and anxiety, can cause the heart to beat faster. A study conducted on mice by researchers at Stanford University in California found that the reverse was also possible. The results, published in the journal Natureshow that the rapid heartbeat generates anxiety in the body.
Do bodily sensations follow emotion or vice versa?
This study comes to answer a question that has intrigued the medical profession for more than a century: do bodily sensations follow emotion or the reverse? To test the phenomenon, the team of American researchers turned to optogenetics, a method that consists of using light to control cellular activity. Scientists have created an optical pacemaker, a tiny vest that incorporates an LED light aimed at the chest. When a mouse’s vest emits a pulse of light, the animal’s heart muscles fire, causing the heart to beat.
The team trained the animals to expect to receive a shock by pressing a lever for a water reward. Using the optogenetic system, scientists artificially accelerated the heart rate of mice from 660 to 900 beats per minute. At this point, the rodents no longer have the reflex to press the lever or find other solutions, which makes them anxious. On the other hand, when the mice do not perceive danger, the heart rate does not influence them. The researchers thus concluded that the brain and the heart actually work together to produce anxiety.
Rethinking treatments for anxiety
By measuring the mice’s brain activity, the researchers found that the insula became more active when the heart rate increased, particularly in a state of anxiety. The insula is a region associated with both emotions and the processing of bodily signals. The researchers then deduce that the insula becomes an intermediary between the heart and the brain in moments of anxiety. It integrates signals from the heart reacting to threats from the environment before transmitting the information to the involved areas of higher cognition.
“The insula area is known to be involved in interoception – the ability to perceive internal states of the body, including heart rate, hunger, temperature and pain“, explains the study.”The insular cortex receives all kinds of information from throughout the body, so it could play a general role in a wide range of emotional states.“, says Dr. Karl Deisseroth, lead author of the study and a professor specializing in psychiatry and behavioral sciences, in the Press release.
This finding could help rethink treatment methods for chronic anxiety disorders. The team of researchers now intends to repeat this system to analyze the links between the human brain and other organs, such as the intestines, or even the muscles of the face.