The nervous and cardiovascular systems have a bidirectional relationship. This means that if there is an injury or imbalance in one system, it will impact the other.
Over the past two decades, many scientific studies have been carried out to gain a deeper insight into this complex intertwining relationship.
Heart health can be seriously impaired with an imbalance in the central nervous system, meaning that emotions can physically impact cardiovascular health.
In this article we’ll explore the heart-brain axis and look how the brain affects the heart – and vice-versa.
How Stress Can Kill You
Did you know that you can die from an extreme stressor? Researchers at Yale University School of Medicine have found that stress can actually lead to sudden death, as the sympathetic nervous system alters heart rhythm in both animals and humans.
Scientists have found that mental stress is exaggerated in people with abnormal heart rhythms. The lead researcher in the Yale study stressed (pardon the pun):
“Patients should be aware that stress really can alter arrhythmias or make heart rhythms dangerous.”
The autonomic nervous system (ANS) and the endocrine system (responsible for releasing hormones) are managed by the central nervous system (CNS). The CNS can be broken down into two parts – the sympathetic nervous system and the parasympathetic nervous system.
This delicate interplay can be thrown off balance with a hyperactive sympathetic nervous system. In this circumstance, the nervous system can seriously injure the heart.
Heart-Brain Axis: A Clinical Perspective
The heart-brain axis has become better understood from a clinical perspective in recent years and can be broken down to the following two approaches:
- The effects of cardiovascular disease on the nervous system (such as strokes).
- The effects of neurological disorders on the cardiovascular system (known as heart brain disorders).
Sudden Death and the Heart-Brain Connection
The brain-heart connection has long been known. Back in 1942, Harvard Medical School Professor of Physiology Walter B. Cannon published an interesting paper entitled “Voodoo Death,” in which he discussed death from fright.
Cannon believed that death from extreme emotions was likely because of “hyperactivity of the sympathetic nervous system”.
Cannon’s work linking intense emotions (like fear) with illness has formed the basis for much of our modern understanding of the physiological response systems. Cannon proposed that the impacts of emotions on the body could be explained as follows: “By a lasting and intense action of the sympathico-adrenal system.”
Today we would refer to the “sympathico-adrenal system” as the HPA-axis and the sympathetic nervous system.
What is the Role of the HPA Axis?
The HPA axis (hypothalamic-pituitary-adrenal axis) is the name we give to a set of interactions between the hypothalamus and the pituitary glands in the brain and adrenals, which are located on top of each kidney.
The HPA axis is our stress response system that is meant for survival purposes. Unfortunately, in modern times chronic stress is normal and people often fall ill due to excessive stress.
Factors That Cause an Autonomic Storm
Overwhelming or life-threatening events that trigger the stress response create an autonomic storm.
During an autonomic storm, the nervous system gets overly stimulated and this can even cause physical cardiac lesions.
George Engel found that sudden death could be tied to the following eight life-altering events:
- The impact of the death of a close person
- During acute grief
- On threat of loss of a close person
- During mourning (or on the anniversary of a sad event)
- On loss of status or self-esteem
- Personal danger or threat of injury
- After danger is over – recurring thoughts of the event
- Reunion, triumph or happy ending
CNS Control of Cardiovascular System
There is a complex interwoven network of neurons that are involved in the processing and control of cardiovascular function.
An area in the brain known as the “insular cortex” is thought to be responsible for the regulation of the heart-brain axis. Stimulating higher cortical centres in animal studies has shown to affect the heart.
The brain region known as the “amygdala” receives information from the prefrontal cortex and is relayed to the hypothalamus. In ideal conditions, this area should modulate the effects of intense emotions on the heart.
What is the Role of the Vagus Nerve?
The autonomic nervous system (ANS) consists of both the parasympathetic and sympathetic parts. This entire system is modulated by the vagus nerve.
The vagus nerve connects the brain to the body. Interestingly, overstimulation of the vagus nerve is the most common cause of fainting.
Stress can over stimulate the vagus nerve and impact your blood pressure and heart rate.
The Sympathetic and Parasympathetic Nervous Systems
The Sympathetic System
A series of enzymatic reactions are involved in the triggering of the sympathetic nervous system.
The sympathetic nervous system (SNS) is commonly known as the fight-or-flight response. Part of the autonomic nervous system (ANS), the sympathetic nervous system is triggered in response to perceived or real stress in our environment.
This activates a cascade of stress hormones called “catecholamines” which include adrenaline and noradrenaline.
Parasympathetic Nervous System
The parasympathetic nervous system is also known as the “rest-and-digest” phase.
This is when we relax and allow our minds and bodies space to recuperate. Just one of the systems can be activated at any time.
Therefore, finding a healthy balance and taking up healthy habits to stimulate your parasympathetic nervous system is important for immune system health.
8 Ways to Calm your Sympathetic Nervous System
A healthy balance between the sympathetic and parasympathetic activity is essential for overall health. However, all too often we find ourselves overwhelmed with stress. Here are 8 natural ways to relax your central nervous system:
- Diaphragmatic breathing
- Eat in a relaxed state
- Time in Nature
- Quality Sleep
Practising all of the above will serve to soothe your sympathetic nervous system for the betterment of your health. What are you waiting for?
Written by best-selling author and integrative nutrition health coach Rowanna Watson, who has a passion for natural health. Rowanna is an expert in all areas of holistic health, plant-based nutrition, detoxification and personal development.
Cannon’s work linking intense emotions with illness has formed the basis for much of our modern understanding of the physiological response systems.