The Ways Loneliness Could Change Your Brain and Body


People were already alone before the coronavirus the pandemic hit. Before COVID-19 locked people at home and made closeness to others an unsettling experience, researchers realized that Americans were lonelier than ever.

A 2018 study by healthcare insurer Cigna found that 54% of 20,000 Americans surveyed said they felt lonely. In just over a year, that figure has risen to 61%. Gen Z adults between the ages of 18 and 22 are expected to be the loneliest generation, overtaking baby boomers, Gen X and Millennials, despite being more connected than ever.

Loneliness has reached epidemic proportions, said Doug Nemecek, chief medical officer at Cigna.

More troubling: A growing body of research suggests that being alone for an extended period of time could be bad for people’s physical and mental well-being.

This same Cigna study placed the associated health risks on par with smoking and obesity.

A 2018 article in The Lancet described the situation as follows: “Imagine a condition that makes a person irritable, depressed and self-centered, and is associated with a 26% increased risk of premature mortality.”

But these are strange times. Due to COVID-19, keeping a distance from others is the surest way to stay healthy, although it can make feelings of isolation worse. It’s a new reason to consider how loneliness can impact everything from your brain to your heart to your immune system.

why we feel alone

Loneliness can conjure up images of being separated from friends and family, but the feeling runs much deeper than having no plans on a Friday night or going to bed at a wedding. Throughout evolution, being part of a group has meant protection, sharing the workload, and increasing the chances of survival. After all, humans take a long time to mature. We need our tribes.

“It’s very painful not to be part of a group,” said Julianne Holt-Lundstad, professor of psychology and neuroscience at Brigham Young University. “We have to manage our environment entirely on our own, without the help of others, which puts our brains on high alert, but also signals the rest of our body to be on high alert.”

Staying in this state of alert, this state of high stress, means wear and tear on the body. According to the Mayo Clinic, stress hormones like cortisol and norepinephrine can contribute to insomnia, weight gain, and anxiety during long periods of exposure.

The pandemic, Holt-Lundstad pointed out, is perhaps the most stressful experience many people have had in their lifetime. Daily life has been turned upside down, unemployment has skyrocketed and more than 6 million people worldwide have been infected. Normally, immense challenges like these would cause you to seek comfort and support from family and friends. But due to the nature of the virus, people are at least more physically alone than ever, making it all the more difficult to deal with.

studying loneliness

Loneliness is something almost everyone can relate to, but scientists are still struggling to understand how and why it affects health. One of the fundamental issues of the research: Loneliness is a subjective feeling that cannot really be measured. Even the size of a person’s social network cannot guarantee how lonely they feel.

Holt-Lundstad said it’s about asking people how they feel in the polls, either directly (how often would you say you’re lonely?) or indirectly (do you feel like you lack company ?).

NASA has studied the effects of isolation and confinement on astronauts for years, reaching some of the same conclusions as countless other studies: isolation conditions can lead to cognitive and behavioral problems. Elsewhere, however, researchers are studying the biological aspects of loneliness and how it physically affects the body.

It may mean looking at the brains.

Researchers at the Rush Alzheimer’s Disease Center in Chicago studied 823 elderly people over a four-year period. They used questionnaires to assess loneliness, classifications of dementia and Alzheimer’s disease, as well as tests of participants’ thinking, learning and memory, and assigned a loneliness score between 1 and 5. They found that a person’s risk factor for Alzheimer’s disease increased by 51% for each point on the scale.

Autopsies were performed on those who died during the study. Loneliness has not been shown to cause the “characteristic brain changes associated with Alzheimer’s disease, including nerve plaques and tangles, or tissue damage from lack of blood flow.” However, a researcher involved in the study, Robert S. Wilson, said loneliness could make people more vulnerable to the “deleterious effects of age-related neuropathology.”

“Solitude [can] be a good predictor of accelerated cognitive decline,” said Turhan Canli, professor of integrative neuroscience at Stony Brook University.


Scientists study loneliness and gene expression.

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The exact link between loneliness and health problems is not fully understood. One idea, Canli said, is that if someone is lonely and feeling bad, they might be less likely to take care of themselves. They might not eat well. They can drink too much, worry a lot, sleep too little. Such habits can have longer term effects.

Canli also talked about the work he’s been involved in with another Rush Alzheimer’s Disease Center researcher, David Bennett, exploring how different genes are expressed in people who are or are not alone.

Some 30 years ago, Bennett initiated a longitudinal study in which participants agreed not only to submit to annual physical and psychological exams, but also to donate their brains when they died. The researchers looked at two brain regions related to cognition and emotion. They found genes associated with cancer, cardiovascular disease and inflammatory disease expressed in those who were more alone.

“There’s actually a network of connections between these different genes through which they can affect each other,” Canli said, “that could be an underlying genetic reason why these diseases might appear based on loneliness.”

This does not mean that loneliness causes heart disease. There is more research to be done, including the role that heritability plays in gene expression. Previous work by a UCLA researcher named Steve Cole has suggested a possibility: the release of certain hormones under the stress of prolonged loneliness could activate certain genes linked to health problems.

“Subjective experience has to be translated somehow in the brain into biology, and so that’s what we’re looking at now,” Canli said.

A better understanding of these relationships could one day influence the therapies designed to treat patients.

The future of loneliness

Even as states begin to ease lockdown orders and restrictions on restaurants, bars and other public places, the role social distancing might play in society is unknown. In April, Harvard researchers said intermittent social distancing may be needed until 2022.

NASA astronaut Scott Kelly, who spent 340 days in space, wrote an article for The New York Times in March offering advice based on his experience. Kelly recommends keeping a journal, sticking to a schedule, and having a hobby.

Nemeck, from Cigna, noted that now more than ever, it’s more important to check in on others and be open to having honest conversations about feelings of loneliness, while fighting the stigma attached to that feeling.

“We need to reach out to friends and make sure we maintain those connections and have meaningful conversations,” he said. “It’s important for all of us to be comfortable asking others how they are feeling.”


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