Illustration: Kieran Blakey

The Nuance

Activating the Vagus Nerve Might Lower Your Covid-19 Risk

While physical distancing and masks are crucial, social interaction could calm the immune system and turn down inflammation

Like other apes, humans are social animals. We evolved to live in codependent communities, and we do poorly if deprived of interpersonal contact.

Everyone has a different threshold for social interaction. But nearly all of us tend to become distressed when cut off from others, and our immune system responds to this distress by ramping up its defenses. A new study in the journal Neuroscience & Biobehavioral Reviews finds that social isolation is associated with a rise in inflammation-promoting molecules, including some that are implicated in severe Covid-19. And past research has linked loneliness to poor cellular immune health and increased viral loads during an infection.

All of these cellular and immune changes are worrying in the context of SARS-CoV-2. Inflammation is a unifying feature of illness, and out-of-control inflammation seems to be a common feature of severe Covid-19.

“People [who have Covid-19] are not dying because of a high viral load, they’re dying because of a high cytokine load,” says Stephen Porges, PhD, a distinguished university scientist at Indiana University. Cytokines are immune cells that can turn up or down inflammation. In many cases of severe Covid-19, pro-inflammatory cytokines surge, and the resulting inflammation causes organ damage and death.

“Our nervous system requires social interaction. Without that information, our bodies can’t calm down.”

Porges says that this now infamous “cytokine storm” can build up for a number of reasons. Medical conditions such as obesity and diabetes — both of which are established risk factors for severe Covid-19 — tend to raise a person’s cytokine load, he says. But so does social isolation.

“Our nervous system requires social interaction,” Porges says. “Without that information, our bodies can’t calm down.”

In some of his work published during the pandemic, he’s made the case that safe and appropriately distanced social engagement is an underappreciated element of Covid-19 prevention and care. In one recent paper, he and his coauthors point out that corticosteroids — drugs designed to turn down the body’s production of pro-inflammatory molecules — have become a mainstay of Covid-19 treatment. But for the most part, public-health officials have done little to promote safe social interaction as a method of calming the immune system and turning down inflammation.

This is where the vagus nerve enters the picture, and particularly an underappreciated branch of the nerve that exerts a calming effect through positive social interaction.

The vagus nerve and social interaction

When people experience anxiety or distress, including the type that stems from social isolation, what they’re actually experiencing is a swell of sympathetic nervous system activity. This system speeds up the heart, slows digestion, and causes a number of other physiological changes that are known collectively as the body’s stress response.

Stress and sympathetic nervous system activity are normal and healthy in moderation. “But if the autonomic nervous system is always in fight-or-flight mode — if it never goes to relaxation — then there’s a loss of balance,” says Peter Payne, a researcher affiliated with the Department of Microbiology and Immunology at Dartmouth College. This loss of balance underlies the immune system dysregulation and runaway inflammation that are associated with chronic stress, and that also seem to play a role in cases of severe Covid-19.

Payne says that the parasympathetic nervous system (PNS) provides the counterweight to this stressed-out state. Sometimes called the “rest and digest” system, PNS activity is associated with feelings of calmness and relaxation. “It’s a very positive and recuperative state,” he says.

The vagus nerve — which is actually a network of nerves that links the brain and immune system to the heart, the gut, and other organs — governs PNS activity. When the vagus nerve is active, Payne says, it acts like a brake on stress and all of its immune-stoking effects in the body.

There are many ways to activate the vagus nerve and its stress-lowering powers. Payne mentions deep breathing, yoga, meditation, and other relaxation techniques that entail “shutting down” or stepping back from life’s stressors. But the vagus nerve has two main branches — one of which seems to have developed in humans much more recently than the other. Payne says that this newer branch seems closely tied to positive social interaction, and it may exert a more robust calming effect on the nervous system.

“In evolutionary terms, activating this branch is a much more advanced way of dealing with distress and balancing the nervous system,” he says.

How to activate the vagus nerve when close contact is risky

Porges says that this newer branch of the vagus nerve is connected to the muscles of the face, head, and throat. This may explain why social interaction — smiling, laughing, talking, listening, emoting — all seem to switch on the vagus nerve and its calming influence.

“What we think of as talking is a form of co-regulation,” he says. “You’re projecting your autonomic state through your tone of voice, and you’re also receiving that from the person you’re talking with.”

“If we don’t have social interaction, the threat of the pandemic is exacerbated.”

While social contact should not take precedence over social distancing, he says that in-person interaction is optimal, and seems safe if people are outside and appropriately distanced and masked. If that’s not possible he says that video-based calls — Zoom, FaceTime, and so on — are good surrogates because they preserve most modes of normal interpersonal exchange. Plus, you can see people’s whole faces. If a video call isn’t possible, a phone call is a good stand-in. “Intonation of voice is an important safety cue we share with one another,” he says. “Think about a mother calming a crying baby, or how a dog responds to its owner’s tone of voice.”

Texting or emails are better than nothing, but inferior to a call. Apart from not being able to see or hear the other person, texting can involve a lot of waiting and even elements of anxiety. “You can get nervous if you don’t get a response,” he points out.

So much of modern medicine is focused on interventions — whether those take the form of a drug, a surgery, or an apparatus like a ventilator. All of those measures have their place. But Porges says that we should also utilize “the body’s own resources” to combat Covid-19, and that includes its ability to calm itself and its inflammatory activity through social interaction.

“The take-home message is that we need to connect as much as we can in any way we know how to,” he adds. “If we don’t have social interaction, the threat of the pandemic is exacerbated.”

I write about health and science. I live in Detroit with my wife and kids. I’m trying to learn German, but my progress so far is nicht gut.

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