Researchers Discover Brain Circuits Causing Physical Responses To Emotional Stress

October 18, 2022

Summary: Science has long known that emotional distress causes multiple physical signs due to stimulating the sympathetic nervous system, causing elevated body temperature, pulse rate, and blood pressure. Although these physical responses may be beneficial in the short run, helping initiate a fight or flight response. Still, they cause much harm in the long run, especially in those living with chronic issues like PTSD and panic disorders. In the new study, researchers discovered the neural circuit that causes these physical responses to stress, which may ultimately help find better treatments.

Mental health disorders are rising, especially emotional health disorders like PTSD and panic disorders. These conditions are known to cause physical signs, like increased heart rate, high blood pressure, increased stress response, and changes in body temperature.

If these altered physical responses remain unhandled, they might lead to changes in body function, increasing the risk of various chronic disorders. However, it is no secret that emotional disorders like anxiety, PTSD, and panic disorders tend to be chronic. Even if these conditions are treated with medications, relapses are common. Of course, there are many ways in which doctors treat both mental and physical signs of emotional disorders. Like they prescribe drugs that calm the brain and modulate emotions. But additionally, doctors also need to manage physical signs of emotional disorders and stress symptoms.

However, most of these treatments are far from adequate. For example, treating physical signs like increased heart rate and blood pressure using a specific drug helps. However, these drugs do not treat the underlying cause. Thus, a greater understanding of how emotional disorders lead to physical signs is needed. Needless to say, emotional responses develop deep inside the brain. Then there are circuits or pathways connecting it with brain centers responsible for controlling various body functions.

The Study Identifies a Brain Circuit Causing Physical Responses to Stress

In the Nagoya University, Japan study, researchers found that stress responses start deep in the limbic system (area of the brain that controls emotions). From there, the signal travels to the dorsal peduncular cortex and the dorsal tenia tecta (DP/DTT), and then this signal is forwarded to the hypothalamus, causing different physical responses. Hypothalamus is like a junction box, connecting deep brain centers to other brain areas that control the sympathetic nervous system and motor system.

It seems that emotional responses mainly stimulate the sympathetic nervous system, which stimulates various body functions, causing high blood pressure, increase in temperature, and heart rate. Although short-term physical responses are the same, the same cannot be said about long-term responses. In the short run, these responses help mammals tackle certain issues and initiate the so-called fight or flight response.

However, the problem is that many people are living with chronic anxiety disorders these days. This means that this circuit responsible for controlling the physical responses to emotional issues remains switched on for days or even months. This continual stimulation of the pathway is the reason why many stress- related disorders, anxiety and panic attacks are increasing globally.

However, as the researchers noted, we can only treat or prevent these conditions if we have a better understanding of the underlying mechanism. Researchers carried out this experiment in lab mice to understand this whole neurocircuit. To confirm that this pathway plays a role in physical responses, they next impaired the connections of DP/DTT to the hypothalamus. This resulted in much less pronounced stress-induced physical responses.

Thus, the study confirmed that it is DP/DTT that is responsible for sending the signal to the hypothalamus and that DP/DTT-to-hypothalamus pathway plays an important role in physical responses to stress and anxiety. This is one of the first studies to identify the role of this particular pathway in stress responses.

Researchers from Nagoya University say that each such finding is a step forward and would help understand the “mind-body connection.” This would ultimately help doctors better treat conditions like PTSD and panic disorders and also help prevent chronic disorders caused by prolonged stress.

By Gurpreet Singh Padda, MD, MBA