The UC Davis-led study analyzed data from 175,000 participants over age 50 across 18 countries, using statistical models to separate the effects of loneliness and social isolation on cognitive outcomes and mortality.

The study was published in the Journal of Personality and Social Psychology on June 15 and was funded by the National Institutes of Health, with co-authors from USC, Northwestern, UCL, and several other institutions.

Reducing loneliness could lower dementia and cognitive-care costs, and hospitals and communities are urged to screen for loneliness and foster social connections for older adults.

Loneliness, the subjective feeling of being alone, emerges as a stronger predictor of cognitive decline and mortality in older adults than objective social isolation, which is merely being physically alone.

A 10% rise in loneliness reports corresponds to about an 8%–9% higher risk of severe cognitive impairment and progression from no impairment to mild impairment, while loneliness also lowers the chance of recovery from mild impairment by roughly 3%.

The findings echo Loneliness Awareness Week’s push to destigmatize loneliness, encourage conversations, and foster opportunities to build social connections.

Younger adults in England reported loneliness more than those aged 65–74, indicating loneliness is not solely an issue of older age.

Context notes clarify that loneliness is a perception that can occur even in crowded settings, whereas isolation is the physical state of being alone; the research was published on June 15 in the Journal of Personality and Social Psychology and NIH-funded.

The article points to potential mechanisms and calls for further research to understand why loneliness may be more detrimental than isolation and how identity intersections shape individuals’ loneliness experiences.

Current prevalence data show loneliness is widespread internationally, with about 22% of adults in England reporting loneliness at least some of the time in 2024, and roughly one in three adults in the USA experiencing loneliness with one in four lacking social and emotional support.

Editorial and methodological notes highlight coordinated analysis across multiple longitudinal studies to resolve prior inconsistencies and to inform public health strategies.

Beyond care costs, researchers advocate for implementing loneliness screenings in hospitals and care networks and building social infrastructures that promote genuine belonging and emotional alignment.