CLOSE

9 Nervy Facts About the Vagus Nerve

What happens in the vagus nerve, it turns out, doesn’t stay in the vagus nerve. The longest of the cranial nerves, the vagus nerve is so named because it “wanders” like a vagabond, sending out fibers from your brainstem to your visceral organs. The vagus nerve is literally the captain of your inner nerve center—the parasympathetic nervous system, to be specific. And like a good captain, it does a great job of overseeing a vast range of crucial functions, communicating nerve impulses to every organ in your body. New research has revealed that it may also be the missing link to treating chronic inflammation, and the beginning of an exciting new field of treatment that leaves medications behind. Here are nine facts about this powerful nerve bundle. 

1. The vagus nerve prevents inflammation.

With a vast network of fibers stationed like spies around all your organs, when the vagus nerve gets wind of the hallmarks of inflammation—cytokines or the inflammatory substance tumor necrosis factor (TNF)—it alerts the brain and elicits anti-inflammatory neurotransmitters via the cholinergic anti-inflammatory pathway. A certain amount of inflammation after injury or illness is normal. But an overabundance is linked to many diseases and conditions, from sepsis to the autoimmune condition rheumatoid arthritis.

2. It helps you make memories.

A University of Virginia study showed success in strengthening memory in rats by stimulating the vagus nerve, which releases the neurotransmitter norepinephrine into the amygdala, consolidating memories. Related studies were done on humans, opening promising treatments for conditions like Alzheimer’s disease.

3. It helps you breathe.

The neurotransmitter acetylcholine, elicited by the vagus nerve, literally gives you the breath of life by telling your lungs to breathe. It’s one of the reasons that botox—often used cosmetically—can be potentially dangerous, because it interrupts your acetylcholine production. You can, however, also manually stimulate your vagus nerve by doing abdominal breathing or holding your breath for four to eight counts.

4. It’s intimately involved with your heart.

The vagus nerve is responsible for controlling the heart rate via electrical impulses to the sinoatrial node of the heart, where acetylcholine release slows the pulse. The way doctors determine the “tone” or “strength” of your vagus nerve (and your cardiac health) is by measuring the time between your individual heart beats, and then plotting this on a chart over time. This is your “heart rate variability.”

5. It initiates your body’s relaxation response.

When your ever-vigilant sympathetic nervous system revs up the fight or flight responses—pouring the stress hormone cortisol and adrenaline into your body—the vagus nerve tells your body to chill out by releasing acetylcholine. Its tendrils extend to many organs, acting like fiberoptic cables that send instructions to release enzymes and proteins like prolactin, vasopressin, and oxytocin, which calm you down. People with a stronger vagus response may be more likely to recover more quickly after stress, injury, or illness.

6. It translates between your gut and your brain.

Your gut uses the vagus nerve like a walkie-talkie to tell your brain how you’re feeling via electric impulses called “action potentials". Your gut feelings are very real.

7. Overstimulation of the vagus nerve is the most common cause of fainting.

If you tremble or get queasy at the sight of blood or while getting a flu shot, you’re not weak; you’re experiencing “vagal syncope.” Your body, responding to stress, overstimulates the vagus nerve, causing your blood pressure and heart rate to drop. During extreme syncope, blood flow is restricted to your brain, and you lose consciousness. But most of the time you just have to sit or lie down for the symptoms to subside.

8. Electric stimulation of the vagus nerve reduces inflammation and may inhibit it altogether.

Truly breaking new medical ground, neurosurgeon Kevin Tracey was the first to prove that stimulating the vagus nerve can significantly reduce inflammation. Results on rats were so successful, he reproduced the experiment in humans with stunning results. The creation of implants to stimulate the vagus nerve via electronic implants showed a drastic reduction, and even remission, in rheumatoid arthritis—which has no known cure and is often treated with the toxic cancer drug methotraxate—hemorrhagic shock, and other equally serious inflammatory syndromes.

9. Vagus nerve stimulation has created a new field of medicine.  

Spurred on by the success of vagal nerve stimulation to treat inflammation and epilepsy, a burgeoning field of medical study, known as “bioelectronics,” may be the future of medicine. Using implants that deliver electric impulses to various body parts, scientists and doctors hope to treat illness with fewer medications and fewer side effects.

Original image
iStock
arrow
Health
New Test Can Differentiate Between Tick-borne Illnesses
Original image
iStock

Time is of the essence in diagnosing and treating Lyme disease and other tick-borne illnesses. Fortunately, one new test may be able to help. A report on the test was published in the journal Science Translational Medicine.

Ticks and the diseases they carry are on the rise. One 2016 study found deer ticks—the species that carries Lyme disease—in more than half of the counties in the United States.

The two most common tick-borne illnesses in the U.S. are Lyme disease and southern tick-associated rash illness (STARI). Although their initial symptoms can be the same, they’re caused by different pathogens; Lyme disease comes from infection with the bacterium Borrelia burgdorferi. We don’t know what causes STARI.

"It is extremely important to be able to tell a patient they have Lyme disease as early as possible so they can be treated as quickly as possible," microbiologist and first author Claudia Molins of the CDC said in a statement. "Most Lyme disease infections are successfully treated with a two- to three-week course of oral antibiotics." Infections that aren't treated can lead to fevers, facial paralysis, heart palpitations, nerve pain, arthritis, short-term memory loss, and inflammation of the brain and spinal cord.

But to date, scientists have yet to create an accurate, consistent early test for Lyme disease, which means people must often wait until they’re very ill. And it’s hard to test for the STARI pathogen when we don’t know what it is.

One team of researchers led by experts at Colorado State University was determined to find a better way. They realized that, rather than looking for pathogens, they could look at the way a person’s body responded to the pathogens.

They analyzed blood samples from patients with both early-stage Lyme disease and STARI. Their results showed that while all patients’ immune systems had mounted a response, the nature of that response was different.

"We have found that all of these infections and diseases are associated with an inflammatory response, but the alteration of the immune response, and the metabolic profiles aren't all the same," senior author John Belisle of CSU said.

Two distinct profiles emerged. The team had found physical evidence, or biomarkers, for each illness: a way to tell one disease from another.

Belisle notes that there’s still plenty of work to do.

"The focus of our efforts is to develop a test that has a much greater sensitivity, and maintains that same level of specificity," Belisle said. "We don't want people to receive unnecessary treatment if they don't have Lyme disease, but we want to identify those who have the disease as quickly as possible."

Original image
iStock
arrow
technology
Google Can Warn You When Your Allergies Are About to Go Haywire
Original image
iStock

How much allergy medication are you going to need today? Google can tell you. Well, it can give you a forecast, at least, as The Verge reports.

Google announced on August 16 that the search engine will now auto-populate search results for pollen and allergy information with allergy forecasts from The Weather Channel. The integration will include the most recent pollen index and allergy forecast data, showing a 5-day forecast detailing whether you’re likely to feel seasonal allergy symptoms throughout the week.

An animation shows a scroll of Google’s search results for pollen with allergy forecasts.
Google

If you have the Google app, you can set it to send push notifications when the pollen count is notably high that day, so you know to sequester yourself safely indoors. Hopefully you don't live in a city like Jackson, Mississippi, which in 2016 was named the worst city in the U.S. for allergy sufferers. There, your phone may be pinging every day.

While you can already find this information on sites like Pollen.com, having it show up immediately in search results saves you a few extra clicks, and frankly, it’s far more readable than most allergy and weather forecast sites.

Too bad a search engine can't cure our sneezes and watery eyes, though. Time to stock up on Kleenex, get a jumbo bottle of allergy meds, and maybe buy yourself a robot vacuum.

[h/t The Verge]

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios