If you do a little research, you will learn that the longest and most complex cranial nerve in the body, the vagus nerve, connects the brain to all the vital organs.
The gut-brain axis relies on this communication highway, which also controls our immune response and parasympathetic nervous system. Keep reading to discover five startling truths about the vagus nerve.
1. The vagus nerve provides communication between the gut and the brain
The enteric nervous system, which you may not be aware of, is like a “second brain” that resides in your gut. The ENS, which consists of 100-500 million neurons, controls certain aspects of digestion, such as fluid secretion and muscle contraction.
Although the gut and brain may seem like strange bedfellows, they are intimately connected and in constant communication. They can communicate through different pathways, but the vagus nerve is the fastest and most important of these channels. It carries messages from the enteric nervous system to the central nervous system and vice versa, similar to a fiber optic cable.
It is interesting to note that most of the vagus nerve signals go from the gut to the brain. Incredibly, the ENS is the only organ in the body that has the ability to function independently of the brain.
According to some studies, microbiota transplantation can induce behavioral changes that can be reversed by severing the vagus nerve. For example, mice whose microbiota have been changed to that of depressed donors show increased levels of pessimism, known as anhedonia.
This is important because this behavior changes when the vagus nerve is severed, indicating that the microbiota can influence mood through vagal transmission. Fascinating, right?
2. The vagus nerve can be stimulated to reduce epileptic seizures
Vagus nerve stimulation (VNS) therapy can help reduce the frequency and severity of seizures in people whose epilepsy does not respond to medication alone, or in people who cannot have brain surgery.
The FDA has approved the use of VNS, a type of bioelectronic medication, for those with treatment-resistant epilepsy. Although it has been used as an epilepsy medication since the 1990s, it is still only used occasionally.
The generator is surgically inserted into the collarbone as part of VNS. The process takes only one to two hours, and the device resembles a pacemaker.
This generator is then set up to send regular moderate electrical impulses to the brain via the vagus nerve, after which a short wire is wrapped around the left vagus nerve.
Although it may sound like something out of a horror movie, the treatment is usually well tolerated; the most common side effects are hoarseness, headaches, and sore throat.
Although researchers do not know how VNS treats epilepsy, it is believed that the electrical signals calm the brain’s erratic electrical activity. They can achieve this by activating neurotransmitters that reduce seizure activity.
Some patients also claim that their mood, memory and attention have improved. This is why you can actually find non-invasive VNS devices that you can use to get these benefits. You can visit vagus.net to learn more about these devices.
3. Treatment-resistant depression can be improved by vagus nerve stimulation
Vagus nerve stimulation for treatment-resistant epilepsy received FDA approval shortly after stories of an unintended mood-enhancing side effect began to circulate.
In light of these observations, some researchers have considered VNS as a potential treatment for persistent depression.
In one trial, 200 people with treatment-naïve depression received vagus nerve stimulation.
No improvement was noted in the first two months, but after a year, 20-30% of subjects showed significant improvement, with half reporting that their symptoms had almost completely disappeared. However, other people’s symptoms do not change or even get worse.
In light of these findings, the FDA approved VNS as a last-resort treatment for people who have not responded to four or more treatment options. VNS is hypothesized to correct imbalances in depressed patients by promoting the generation of feel-good neurotransmitters.
4. Fainting may be the result of an overreaction of the vagus nerve
The vagus nerve could have played a role in any fainting you experienced after the injection or seeing blood. Vasovagal syncope, or overreaction of the vagus nerve, can sometimes lead to unconsciousness.
In other words, certain stimuli cause a strong parasympathetic response, significantly reducing heart rate and blood pressure. If the brain does not receive enough blood for a short period of time, the person may lose consciousness.
The vagus nerve regulates these physiological changes, resulting in inadequate blood flow to the brain. Vasovagal syncope accounts for a staggering 80% of fainting spells in people under the age of forty. It’s not clear why this happens, but one idea is that the body is preparing for damage and trying to reduce blood loss.
5. Stomach problems can be the result of damage to the vagus nerve
Many medical conditions, such as type 2 diabetes and surgery on the stomach or esophagus, can damage the vagus nerve. A hoarse voice, a weak gagging reaction, and trouble swallowing are signs of damage.
In addition to these symptoms, damage to the vagus nerve can also cause stomach problems. For example, gastroparesis, a long-term condition in which the stomach cannot empty food properly, is known to be caused by damage to the vagus nerve.
As mentioned earlier, the vagus nerve controls various digestive processes, including muscle contractions (peristalsis) that move food through the intestinal system.
The signals that trigger peristalsis can be disrupted when the vagus nerve is damaged, leading to a wide range of digestive problems such as diarrhea, bloating, nausea, cramping, and more.
The vagus nerve is an important part of the digestive system. It helps in many great things and can lead to problems as well if it is damaged. We hope these interesting facts help you learn more about this all-important nerve.