COVID-19, loneliness, social isolation and risk of dementia in older people: a systematic review and meta-analysis of the relevant literature.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of non-randomized cohort studies
PubMed 34369248 · doi:10.1080/13651501.2021.1959616
What was done
Authors conducted a systematic review and random-effects meta-analysis of 10 cohort studies evaluating the association between social isolation and feelings of loneliness (SIFL) and incident dementia. Eligible studies examined community-dwelling adults aged 50 years and older without baseline dementia, with cohorts averaging 8,239 participants followed for a mean duration of 6.41 years. Analyses pooled Cox proportional hazard ratios and relative risks across the included studies.
What was found
Prolonged loneliness and social isolation were associated with a statistically significant increase in dementia risk of approximately 49% to 60% compared to non-isolated counterparts (pooled HR = 1.49, 95% CI: 1.37 to 1.61).
Why it matters
These findings quantify the longitudinal association between social disconnection and cognitive decline, emphasizing the importance of social connection in older adults.
Limits
The underlying evidence is observational, leaving open the possibility of residual confounding or reverse causality where prodromal dementia leads to social withdrawal. The analysis combined hazard ratios and relative risks across opportunistic cohorts, and the underlying primary studies reflect general pre-existing cohorts rather than direct empirical measurements of dementia incidence directly caused by COVID-19 lockdowns.
Cited by
- supports Social isolation is a risk factor for dementia.