Loneliness (as health risk)

Loneliness, the subjective feeling of social disconnection, is now recognised as an independent risk factor for cardiovascular disease, dementia, and early mortality. Meta-analyses by Holt-Lunstad and colleagues found that strong social relationships were associated with ~50% greater odds of survival (2010, PLOS Medicine), and that social isolation, loneliness, and living alone independently raise all-cause mortality risk by roughly 26–32% (2015, Perspectives on Psychological Science) — an effect Holt-Lunstad has compared by analogy to the mortality risk of smoking up to 15 cigarettes a day, a framing later cited in the 2023 US Surgeon General's Advisory on the epidemic of loneliness and isolation. It dysregulates inflammation, sleep, and HPA-axis stress responses. In longevity science, addressing loneliness through community, purpose, and relationships is a primary, evidence-based intervention.