Harvard Mental Health Letter

In Brief: Social relationships and longevity

Since the late 1980s, studies have suggested that people who enjoy close relationships with family and friends are more likely to live longer than people who are isolated and lonely. In an attempt to better determine just how much social relationships affect longevity, researchers conducted a meta-analysis of 148 longitudinal studies involving more than 300,000 people. Participants were 64 years old, on average, when they entered the studies, and investigators followed them an average of 7.5 years, assessing the frequency and type of social relationships they reported as well as health outcomes, including mortality.

On the basis of their review, the authors of the meta-analysis estimated that older people with adequate social relationships have a 50% greater likelihood of survival when compared with those who are isolated or have poor social relationships. They further estimated that people who have regular contact with friends, family, and neighbors have a survival advantage comparable in magnitude with kicking the smoking habit and about twice as large as the longevity benefit that comes from exercising regularly or maintaining a normal weight.

Two psychological theories exist about why social relationships are so good for health. The buffering hypothesis holds that people who enjoy close relationships with spouses, family, and friends receive emotional support that indirectly helps to sustain them at times of stress and crisis. The main effects hypothesis is more focused on direct and tangible types of support. According to this theory, family and friends may encourage an individual to make healthier lifestyle choices and to seek medical care when illness strikes.

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