The Ways Loneliness Can Change Your Brain and Body

People were lonely before the coronavirus pandemic hit. Before COVID-19 stranded people at home and made being close to others a nerve-wracking experience, researchers realized that Americans were lonelier than ever.

A 2018 survey by health insurer Cigna found that 54% of the 20,000 Americans surveyed reported feeling lonely. In just over a year, the number rose to 61%. Generation Z adults aged 18-22 are arguably the loneliest generation, surpassing 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 worryingly, a growing body of research suggests that prolonged loneliness can be bad for people’s physical and mental well-being.

That same study by Cigna placed the associated health risks on a par with smoking and obesity.

A 2018 article in The Lancet described the situation this way: “Imagine a condition that makes a person irritable, depressed and egocentric, and is associated with a 26% increase in the risk of premature death.”

But these are strange times. Due to COVID-19, keeping distance from others is the safest way to stay healthy, despite the fact that it can amplify feelings of isolation. It’s another reason to think about how loneliness can affect everything from your brain to your heart to your immune system.

Why do we get lonely?

Loneliness may 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 bachelorette parties. Evolutionarily speaking, being part of a group meant protection, sharing the workload, and a greater chance of survival. After all, people take a long time to grow up. We need our tribes.

“It’s very disturbing when we’re not part of a group,” said Julianne Holt-Lundstad, a professor of psychology and neuroscience at Brigham Young University. “We have to deal with our environment all by ourselves, without the help of others, which puts our brain in a state of alert, but also signals the rest of our body to be in a state of alert.”

Staying in that state of alert, that high state of stress, means wear and tear on the body. According to the Mayo Clinic, stress hormones such as cortisol and norepinephrine can contribute to insomnia, weight gain and anxiety with prolonged exposure.

The pandemic, Holt-Lundstad noted, is possibly the most stressful experience many people have had in their lives. Daily life has been turned upside down, unemployment has skyrocketed and more than 6 million people around the world have been infected. Normally, huge challenges like that would make you seek the reassurance and support of family and friends. But due to the nature of the virus, at least people are more physically alone than ever, making it that much harder to deal with.

Studying Loneliness

Loneliness is something almost anyone can relate to, but scientists are still trying to understand how and why it affects health. One of the fundamental challenges 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 are.

Holt-Lundstad said it’s a matter of asking people how they feel in surveys, either directly (how often would you say you’re lonely?) or indirectly (do you feel like you don’t have company?).

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

That may mean looking at the brain.

Researchers at the Rush Alzheimer’s Disease Center in Chicago studied 823 older adults over a four-year period. They used questionnaires to rate loneliness, classifications of dementia and Alzheimer’s disease, as well as tests of the participants’ thinking, learning and memory, and gave a loneliness score between 1 and 5. They found that a person’s risk factor for the disease 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 “signature brain changes associated with Alzheimer’s disease, including nerve plaques and tangles, or tissue damaged by lack of blood flow.” However, a researcher involved in the study, Robert S. Wilson, said loneliness can make people more vulnerable to the “harmful effects of age-related neuropathology.”

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


Scientists look at loneliness and gene expression.

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Exactly how loneliness is related to health problems is not fully understood. One idea, Canli said, is that if someone is lonely and not feeling well, they are less likely to take care of themselves. They may not eat well. They may drink too much, worry a lot, sleep too little. Habits like that can have long-term effects.

Canli also spoke about his work with another researcher at the Rush Alzheimer’s Disease Center, David Bennett, who studies how different genes are expressed in people who may or may not be lonely.

Some 30 years ago, Bennett embarked on a longitudinal study in which participants agreed not only to annual physical and psychological checkups, but also to donate their brains when they died. Researchers looked at two brain regions linked to cognition and emotion. They found genes associated with cancer, cardiovascular and inflammatory diseases that were expressed in those who were lonelier.

“There’s actually a network of connections between these different genes that allows them to influence each other,” Canli said, “that could be an underlying genetic reason why these diseases can appear as a function of loneliness.”

That’s not to say loneliness causes heart disease. There is more research to be done, including the role that heredity plays in gene expression. Previous work by a UCLA researcher named Steve Cole suggested one possibility: The release of certain hormones while under the stress of persistent loneliness could activate certain genes linked to health problems.

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

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

The future of loneliness

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

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

Nemeck, of Cigna, noted that now more than ever it is more important to check in with others and be open to honest conversations about feelings of loneliness, while brushing aside the stigma associated with the feeling.

“We need to reach out to some friends and make sure we maintain those connections and have meaningful conversations,” he said. “It’s important that we all feel comfortable asking other people how they feel.”