Researchers reviewed 148 studies (amounting to 308,849 participants) and found that stronger social connections resulted in a 50% increased likelihood in survival where participants had stronger social connections. This remained consistent across age, gender, initial health status, cause of death and follow up period. The researchers concluded that the influence of social relationships on risk for mortality is comparable with well-established risk factors for mortality such as smoking and alcohol consumption and exceeds the influence of other risk factors such as physical inactivity and obesity. As such social connectedness should be taken as seriously as other factors that influence mortality.
Holt-Lunstad J, Smith TB, Layton JB (2010) Social Relationships and Mortality Risk: A Meta-analytic Review. PLoS Med 7(7): e1000316. https://doi.org/10.1371/journal.pmed.1000316