Social connection

Practical note

Graded moderate as a prognostic association (GRADE for prognostic factors starts cohort evidence high): 148 studies with 308,849 participants and a consistent direction across age, sex, initial health status and cause of death; downgraded one level for heterogeneity in how relationships were measured and possible residual confounding. The association was strongest for complex measures of social integration (OR 1.91) and weakest and not significant for living alone versus with others (OR 1.19). This is observational evidence and does not show that changing social relationships changes survival.

Sources

• Supports“Across 148 studies (308,849 participants), the random effects weighted average effect size was OR = 1.50 (95% CI 1.42 to 1.59), indicating a 50% increased likelihood of survival for participants with stronger social relationships.” (Abstract, Results) Holt-Lunstad J, Smith TB, Layton JB. 2010. PLoS Medicine. Social relationships and mortality risk: a meta-analytic review. CC BY (Creative Commons Attribution License); credit Holt-Lunstad et al., PLoS Medicine 2010
• Context“Strong social connections can lead to better health and longer life, the report says.” (Opening paragraph) World Health Organization. 2025. WHO news release (WHO Commission on Social Connection report). Social connection linked to improved health and reduced risk of early death. WHO copyright; short attributed quotes only; credit the World Health Organization

Practical note

Graded moderate as a prognostic association from a meta-analysis of confounder-adjusted cohort studies (odds ratios 1.29 for social isolation, 1.26 for loneliness, 1.32 for living alone); downgraded one level because initial health status influenced the findings, which leaves room for reverse causation. Objective isolation and subjective loneliness showed similar associations, and associations were stronger in samples with an average age under 65.

Sources

• Supports“corresponding to an average of 29%, 26%, and 32% increased likelihood of mortality, respectively.” (Abstract) Holt-Lunstad J, Smith TB, Baker M, Harris T, Stephenson D. 2015. Perspectives on Psychological Science. Loneliness and social isolation as risk factors for mortality: a meta-analytic review. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine
• Context“Loneliness is linked to an estimated 100 deaths every hour—more than 871 000 deaths annually.” (Opening paragraph) World Health Organization. 2025. WHO news release (WHO Commission on Social Connection report). Social connection linked to improved health and reduced risk of early death. WHO copyright; short attributed quotes only; credit the World Health Organization

Practical note

Graded low: a 2016 meta-analysis of longitudinal studies found pooled relative risks of 1.29 for coronary heart disease (11 studies) and 1.32 for stroke (8 studies), but the confidence intervals reach close to no effect (lower bounds 1.04), the studies were few and limited to high-income countries, and residual confounding is possible.

Sources

• Supports“Poor social relationships were associated with a 29% increase in risk of incident CHD (pooled relative risk: 1.29, 95% CI 1.04 to 1.59) and a 32% increase in risk of stroke” (Abstract, Results) Valtorta NK, Kanaan M, Gilbody S, Ronzi S, Hanratty B. 2016. Heart. Loneliness and social isolation as risk factors for coronary heart disease and stroke: systematic review and meta-analysis of longitudinal observational studies. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine
• Context“In contrast, loneliness and social isolation increase the risk of stroke, heart disease, diabetes, cognitive decline, and premature death.” (Impacts on health, quality of life and economies) World Health Organization. 2025. WHO news release (WHO Commission on Social Connection report). Social connection linked to improved health and reduced risk of early death. WHO copyright; short attributed quotes only; credit the World Health Organization

Practical note

Graded low: a 2015 meta-analysis of 19 longitudinal cohort studies found pooled relative risks of 1.41 for low social participation, 1.57 for less frequent social contact and 1.58 for more loneliness; downgraded for inconsistency (results for social network size were inconsistent and satisfaction with the network showed no significant association) and for possible reverse causation, since withdrawal from social life can be an early sign of cognitive decline.

Sources

• Supports“We conclude that social relationship factors that represent a lack of social interaction are associated with incident dementia.” (Abstract) Kuiper JS, Zuidersma M, Oude Voshaar RC, Zuidema SU, van den Heuvel ER, Stolk RP, Smidt N. 2015. Ageing Research Reviews. Social relationships and risk of dementia: A systematic review and meta-analysis of longitudinal cohort studies. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine

Practical note

Graded low, matching the review authors' own GRADE rating of low or very low: a 2026 meta-analysis of 280 studies (122 randomised trials, standardised mean difference about -0.50 in the trials) and a 2024 umbrella review of 29 systematic reviews both found benefits but noted heterogeneity and variable study quality. An earlier 2011 meta-analysis found that non-randomised designs gave larger effects than randomised ones and that, among randomised studies, interventions addressing maladaptive social cognition did best. Effects 1 to 6 months after the intervention were comparable to short-term effects.

Safety note

Loneliness that comes with persistent low mood, anxiety or thoughts of self-harm is a reason to talk to a health professional rather than rely on self-directed approaches.

Sources

• Supports“Psychological interventions appeared to be the most effective intervention strategy for reducing loneliness, demonstrating a moderate effect” (Abstract) Lasgaard M, Qualter P, Løvschall C, Laustsen LM, Lim MH, Sjøl SE, Burke L, Blæhr EE, Maindal HT, Hargaard AS, Christensen R, Christiansen J. 2026. American Psychologist. Are loneliness interventions effective for reducing loneliness? A meta-analytic review of 280 studies. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine
• Supports“This overview of SRs shows small to moderate effectiveness of social interventions in reducing social isolation and psychological ones in tackling loneliness.” (Abstract, Conclusions) Hansen T, Nes RB, Hynek K, Nilsen TS, Reneflot A, Stene-Larsen K, Tornes RA, Bidonde J. 2024. BMC Public Health. Tackling social disconnection: an umbrella review of RCT-based interventions targeting social isolation and loneliness. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine
• Context“Confidence in the estimates was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation system and graded as low or very low.” (Abstract) Lasgaard M, Qualter P, Løvschall C, Laustsen LM, Lim MH, Sjøl SE, Burke L, Blæhr EE, Maindal HT, Hargaard AS, Christensen R, Christiansen J. 2026. American Psychologist. Are loneliness interventions effective for reducing loneliness? A meta-analytic review of 280 studies. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine
• Context“Among studies that used the latter design, the most successful interventions addressed maladaptive social cognition.” (Abstract) Masi CM, Chen HY, Hawkley LC, Cacioppo JT. 2011. Personality and Social Psychology Review. A meta-analysis of interventions to reduce loneliness. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine