A lack of social connection has been found to be as deadly as smoking 15 cigarettes a day, and to be an even stronger predictor of mortality than obesity, according to new meta-analyses of more than 100 studies involving hundreds of thousands of subjects.
The evidence suggests policymakers should treat social connectivity as a matter of public health, according to Julianne Holt-Lunstad, professor of psychology and neuroscience at Brigham Young University in Provo, Utah.
According to the new research, just feeling lonely or living alone are each stronger predictors of mortality than obesity.
“I was able to analyze the cumulative data on how being socially connected, or lacking social connections, influences our longevity,” Holt-Lunstad said. “Yes, this should be a public health issue.”
Holt-Lunstad’s conclusions are drawn from two meta-analyses, which she presented at the 125th Annual Convention of the American Psychological Association in Washington DC on Saturday.
The first draws on 148 studies involving more than 300,000 participants that reveals greater social connection is associated with a 50 percent reduced risk of early death — and poor social connectivity is as strong an indicator of mortality as smoking 15 cigarettes a day.
The second analysis, which drew on 70 studies representing more than 3.4 million people, examined the role that three similar but distinct factors have on mortality: social isolation, loneliness, and living alone.
RELATED: Loneliness and Self-Centeredness Amplify Each Other in a Vicious Feedback Loop
Holt-Lunstad is careful to distinguish between those terms. Social isolation indicates a lack of contact with others, whereas loneliness is merely the subjective feeling of being lonely, no matter how many close relationships you appear to be from the outside.
Holt-Lunstad’s analysis found that all three had a significant and similar effect on the risk of premature death — and that each one, alone, was a stronger predictor of mortality than obesity.
In other words, just feeling lonely often is worse for your health than obesity.
“We only looked at disease-related mortality, and we didn’t take into account accidents or suicide,” Holt-Lunstad said. “And of course, being socially isolated and lonely are also associated with increased risk for suicide. So ours is actually a conservative estimate.”
In Holt-Lunstad’s research, “social connection” refers to more than just the amount of contact someone has with others. It also accounts for the type of relationships and the subjective perception of the quality of those relationships.
There are several reasons why connectivity is thought to boost health.
Strong social bonds are believed to help people cope with stress, which has been linked to a wide range of illnesses. Friends and family may encourage loved ones to take better care of themselves, or to see a doctor when something seems wrong. Relationships are associated with having a sense of meaning and purpose in life — which are themselves correlated with better self-care and less risk-taking.
“There’s a growing body of evidence that our relationships have direct influence on health-relevant physiological processes including blood pressure, inflammation, cellular aging and immune processes,” Holt-Lunstad said.
If the lack of social connection is a health hazard, the data suggests that it’s getting worse, Holt-Lunstad said.
Approximately 42.6 million adults over age 45 in the United States may be suffering from chronic loneliness, according to a loneliness study conducted by the American Association of Retired Persons.
In addition, the most recent US census data shows more than a quarter of the population lives alone, more than half of the population is unmarried, and marriage rates and the number of children per household have declined.
RELATED: To Friend or Unfriend? How Your Relationship Style Plays Out in Social Networks
One big remaining unknown is whether our growing dependence on digital communication, like text messaging and social media, have a mitigating effect on the health hazards associated with low levels of in-person social connection.
Much of the data Holt-Lunstad used for her mega-analyses was gathered from studies performed before cell phones proliferated widely.
It’s not yet clear whether staying better connected to your friends through your phone has the same health benefits as meeting up with them in person, she said.
“There’s reason to suggest it may not be,” she said. “But I hate to make that assumption, because we don’t know.”
For now, Holt-Lunstad points out, we do know that there’s at least one thing a phone can’t replicate that’s been proven to have stress-reducing properties: physical touch.
WATCH: Why Loneliness Can Be Deadly