Stimulating the vagus nerve reveals medical potential for a range of health conditions
Science Photo Library/Alamy
The US Food and Drug Administration (FDA) has granted approval for a vagus nerve stimulation device aimed at treating rheumatoid arthritis. This marks the first time a device like this has been authorized for an autoimmune disorder, opening possibilities for broader medical uses.
The small, tablet-sized device is surgically placed alongside the vagus nerve, which consists of nerve fibers connecting the brain to vital organs. It automatically administers electrical pulses that stimulate the nerves and help reduce inflammation for up to a decade.
Rheumatoid arthritis, similar to other autoimmune disorders, leads to excessive inflammation, causing the body to mistakenly attack its own tissues, resulting in pain, swelling, and potential organ damage. Treatment typically involves strong anti-inflammatory medications that suppress the immune system, increasing vulnerabilities to infections and cancer. Nearly 75% of rheumatoid arthritis patients express dissatisfaction with current therapies and have discontinued them due to adverse side effects.
In clinical trials, 242 participants with moderate to severe rheumatoid arthritis were tested, showing that about 35% of those receiving vagus nerve stimulation for 12 weeks experienced at least a 20% reduction in symptoms compared to only 24% in the placebo group. Less than 2% faced serious side effects, and none developed severe infections.
“Utilizing a safe computer chip as an alternative to expensive, minimally effective medications with significant side effects presents an appealing option for many patients,” remarked Kevin Tracy from the Feinstein Institute of Medicine in New York. He originated the device approximately two decades ago while working with Setpoint Medical, a US medical technology firm that is no longer operational.
This approval signifies a pivotal advancement toward potentially treating various inflammation-related ailments, including heart failure, diabetes, and neurodegenerative disorders such as Parkinson’s disease, through vagus nerve stimulation. Stavros Zanos at the Feinstein Medical Institute emphasizes that SetPoint Medical’s device is already being evaluated in clinical trials for conditions like multiple sclerosis and inflammatory bowel disease.
Your brain communicates with your body through a network of 12 critical neural pathways that travel down your spine and extend throughout the body. Among these, the vagus nerve stands out as perhaps the most vital. This nerve influences digestion, heart rate, reflexes, and respiration.
This is why researchers are particularly fascinated by the vagus nerve’s functions, especially regarding how these bodily activities can influence your mood. Consider it a superhighway linking our brains and bodies.
Vagus nerve function
Unlike the quick “fight or flight” reactions managed by the sympathetic nervous system, the vagus nerve triggers a slower, restful, and digestive response associated with the parasympathetic nervous system. This nerve comprises two thick cords of neurons (nerve cells) that originate from the brain.
The majority of the neurons in the vagus nerve are sensory (around 100,000 on each side of the body), relaying information from the organs to the brain, activated by sensory stimuli from the surrounding environment. The remaining neurons are motor neurons, transmitting signals from the brain to various organs, directly influencing muscle activity.
The vagus nerve is a vital component of the parasympathetic nervous system, influencing various bodily functions including respiration, heart rate, swallowing, sneezing, digestion, appetite, immune responses, and even orgasm.
This wide-ranging capability results from its diverse neuronal cell types that enable the detection of various sensory signals from different organs. Some neurons respond to chemical signals like blood oxygen levels or bacterial secretions in the gut, while others pick up mechanical signals from blood vessels and the stretching of intestines.
Consequently, vagus nerve neurons mainly relay information to the brain about the body’s status, enabling the brain to process this information and respond to maintain balance. However, some neurons transmit signals in reverse, facilitating communication between the brain and intestines, as well as controlling certain mouth and throat muscles involved in speech and gag reflexes.
The vagus nerve’s roles are numerous, and there may be functions we’re yet to discover. However, we know some ways to leverage its activity. For instance, doctors sometimes recommend “Valsalva Maneuvers” to activate the vagus nerve and decelerate rapid heart rates. Activities like coughing, bearing down as if on the toilet, or even handstands can be effective.
Read more about stress:
Long, twisty nerves
The term “vagus” translates to “wandering” in Latin, which aptly describes the vagus nerve. It extends from the brain down to the base of the spine and colon, branching out to critical organs such as the heart, lungs, liver, and intestines along its path.
As the longest cranial nerve in the human body, it plays a key role in the parasympathetic nervous system, regulating automatic functions like digestion while the body is at rest. Historically, it was termed the pneumonia nerve, due to its connections to both the lungs and stomach.
How is the vagus nerve connected to our happiness?
In stressful situations, our sympathetic nervous system triggers “fight or flight” responses for quick reactions, whereas the parasympathetic system operates more gradually to foster relaxation. It’s crucial for recovering calmness following stress.
Thanks to the vagus nerve, our brains can detect changes in breathing and heart rate, facilitating a balancing act between the two nervous systems. Although the sympathetic and parasympathetic systems don’t always sync perfectly, they can operate independently or in harmony. Disruptions in their balance may lead to digestive issues or mental health disorders. Chronic stress is linked to an overactive sympathetic response, a phenomenon noted in individuals suffering from depression.
Vagus nerve and heart
A key metric often utilized is heart rate variability, which measures the intervals between consecutive heartbeats. Healthy heart rhythms typically exhibit slight variations; low variability may indicate an overactive sympathetic nervous system, indicating the body remains in a persistent state of combat or flight, while the vagus and parasympathetic responses struggle to keep pace.
Despite being a popular tool, questions regarding the true effectiveness of heart rate variability as an indicator of balance between the two systems continue to emerge. Heart rate monitors can supply this data, yet it’s best not to become overly fixated on the figures.
Historically, stomach ulcers were often treated by severing the vagus fibers beneath the ribcage, based on the belief that the vagus nerve significantly contributes to acid production in the stomach, resulting in pain. Today, with advancements in medication, such surgical procedures are less common, yet they illustrate the repercussions of damaging a nerve with extensive branches.
Cutting the vagus nerve can eliminate its supply to the stomach, pancreas, small intestine, and portions of the colon. Without further surgical intervention, patients may find it difficult to pass solid waste. Those with gastroparesis face similar challenges, generally due to vagus nerve damage caused by diabetes, medications, or infections.
Moreover, more severe damage higher up the vagus nerve may lead to different consequences. For example, the chickenpox virus can attack the nervous system and rarely cause vagus nerve lesions, resulting in the inability to swallow, headaches, and ear inflammation. Preliminary research from Spain indicates that some of the symptoms associated with long COVID may also relate to vagus nerve damage, encompassing respiratory, vocal, and gastrointestinal issues.
Should I get a vagus nerve stimulator?
Current evidence indicates that devices designed for vagus nerve stimulation are generally safe. However, researchers express concerns about the rising tendency for home use of neurostimulators.
Individuals seeking alternatives to technology may opt for activities like yoga, meditation, hypnotherapy, and deep breathing exercises, believed to enhance the parasympathetic nervous system’s function and bolster vagus nerve activity. Additionally, there’s evidence suggesting that cold exposure through swimming or bathing can stimulate the vagus nerve, activating the parasympathetic system. Splashing cold water on your face may also have a similar effect.
While using an inexpensive device or signing up for a yoga retreat may appear to be a convenient fix when you’re not feeling well, consulting with your doctor for serious health concerns is always a wise approach.
Read more about how to relax:
What is vagus nerve stimulation?
The vagus nerve stimulation concept originated in the late 19th century when neurologist James Leonard Corning created an electrical stimulation device for treating epilepsy. Although it was initially set aside, it has evolved to help over 100,000 patients with epilepsy via implants or adjustments for brain lesions.
Several studies suggest that some individuals can reduce seizure frequency by as much as 75% with implants, with longer use amplifying benefits. Devices developed by US medical company Cyberonics are also approved for severe depression and chronic headaches.
However, surgical implantation isn’t the only form of nerve stimulation. You can access the vagus nerve via ear and neck branches, using devices like TENS machines commonly utilized for labor pain relief. Ear clips, such as those developed by Nurosym, offer stylish neuromodulators intended for individuals seeking relief from anxiety, depression, or fatigue.
Research on vagus nerve stimulation is rapidly growing, with ongoing trials exploring its efficacy in conditions like burns, obesity, hypertension, rheumatoid arthritis, Alzheimer’s disease, and tinnitus. The well-documented link between the vagus nerve and gut function also suggests potential therapeutic applications for common gastrointestinal disorders like IBS. However, accumulating evidence to support these treatments must take time.
It is the longest cranial nerve that extends from the brain to the large intestine, transmitting signals bidirectionally through neurotransmitters and gut hormones.
The vagus nerve fibers harbor 200,000 sensory nerve cells, with the ears being the sole area where these fibers reach the body’s surface.
The vagus nerve’s “bypass,” which enables direct impulses between the uterus and brain, may allow women with spinal injury to achieve orgasm.
Vagus nerve stimulation influences gamma-aminobutyric acid neurotransmitters associated with ADHD, hinting at potential therapeutic applications.
The medical term for fainting is vasovagal syncope, occurring when the vagus nerve is overstimulated, leading to a sudden drop in heart rate and blood pressure.
Read more about the human body:
To submit your question, please email Questions@sciencefocus.com (don’t forget to include your name and location)
Urinary tract infections often cause you to need to urinate more often than usual
Simple Images/Getty Images
Pain that persists even after a urinary tract infection appears to be cured may be caused by an overgrowth of nerve cells in the bladder.
Urinary tract infections (UTIs) are most commonly caused by bacteria. Escherichia coli From the feces, it reaches the urethra, bladder, and kidneys. Common symptoms include pain when urinating and an urge to urinate more frequently than usual. These infections primarily affect women, but About half of them will develop a urinary tract infection at some point in their lives.
“One of the big problems with urinary tract infections is that the recurrence rate is very high,” he says. Soman Abraham At Duke University, North Carolina. “However, after treatment, some people may experience the same symptoms of a urinary tract infection even if the infection is gone.”
To understand the root of the ongoing symptoms, Abraham and his colleagues reported persistent pelvic pain due to recurrent urinary tract infections, even though examination revealed no pain.8 analyzed bladder tissue biopsies taken from human women. Escherichia coli in their urine. They also collected biopsies from three women who were not known to have had urinary tract infections. The study did not include transgender people.
The researchers found that women with persistent UTI symptoms had an abnormal overgrowth of nerve cells in their bladders compared to other women. These nerve cells also contained high levels of a peptide called substance p, which causes pain and inflammation.
The researchers then gave the mice recurring urinary tract infections and found that they showed similar persistent signs of pain even after the infection had subsided. When the researchers looked closely at the mouse bladders, they found that immune cells called mast cells, which are located near nerve cells, were highly activated. Mast cells produce so-called nerve growth factors, which stimulate the production of nerve cells.
Antibiotics used to treat UTIs are often less selective for the bacteria they target, affecting beneficial bacterial strains around nerve cells. This damages nerve cells, causing mast cells to work overtime to help replace them, Abraham says.
In the final part of the experiment, the researchers induced urinary tract infections in another set of mice before treating them with a compound that suppresses the production of nerve growth factor. He then induced two more urinary tract infections and found that the mice showed no signs of lingering pain.
The research team hopes the results will help develop effective treatments to prevent ongoing symptoms in people. “You can actually prevent these nerves from growing, which can prevent pain and urinary frequency,” Abraham says.
This website uses cookies so that we can provide you with the best user experience possible. Cookie information is stored in your browser and performs functions such as recognising you when you return to our website and helping our team to understand which sections of the website you find most interesting and useful.
Strictly Necessary Cookies
Strictly Necessary Cookie should be enabled at all times so that we can save your preferences for cookie settings.
