Weak social ties carried a risk on par with smoking

Researchers at Brigham Young University pooled data from 148 earlier studies, covering more than 308,000 people in total, to ask how someone's social relationships, from marriage to casual community ties, related to how long they lived.

People with stronger social relationships had about a 50 percent greater likelihood of surviving over the study periods than people with weaker ones, a gap comparable in size to the known mortality difference between smokers and nonsmokers, and larger than the gap tied to obesity or physical inactivity.

The effect held up regardless of age, sex, or how healthy someone was to begin with, and it was strongest for complex measures of social integration rather than simple ones like living alone or being married. Because the underlying studies were observational, the analysis could not fully separate cause from effect, since people who are already ill or depressed also tend to withdraw from relationships.

Connection, measured like a vital sign.