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Home › Research › What the research found › Every row

Every row of the evidence table

One row per finding: what was tested, which way the result went, and how the study was built. The answer by area, and where the studies disagree, are on the main page.

Every row

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Area All 382 Care, carers and services 140 Medicines 85 Genes (not modifiable) 35 All modifiable factors together 27 Diet and supplements 23 Exercise and activity 21 Sleep, mood and social life 19 Hearing and vision 8 Alcohol, tobacco and cannabis 6 Infection and vaccination 5 Heart and metabolic health 4 Injury, delirium and falls 4 Environment 3 Cognitive activity 2
Question Both Prevention 190 Treatment 192
Direction Any Benefit 144 Harm 105 No effect 38 Mixed 37 No direction reported 58
Design Any meta-analysis 57 randomised trial 44 phase 3 trial 15 systematic review 9 phase 2 trial 10 cohort study 136 phase 1 trial 2 cross-sectional study 31 case-control study 14 modelling study 20 regulatory decision 7 company announcement 1 coverage determination 1 None 35
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Showing 3 of 382 rows for Social isolation / loneliness. One row per study per exposure: a study that tested two different things appears twice, once for each.

Scroll the table sideways to see every column.

Research and outcomes, 3 rows. Every row links to its source.
Exposure Question Direction Outcome measured Design People Effect size, as the source reported it Source
Social isolation / loneliness Sleep, mood and social life Prevention Harm
why

Persisted after controlling for depression and social isolation.

 Incident all-cause dementia meta-analysis 608,561 All-cause dementia HR 1.306 (95% CI 1.197-1.426); Alzheimer's disease HR 1.393 (95% CI 1.290-1.504, 5 samples); vascular dementia HR 1.735 (95% CI 1.483-2.029, 3 samples); cognitive impairment HR 1.150 (95% CI 1.113-1.189, 16 samples) Nature Mental Health 2024
✓ Peer-reviewed PMID 39802418
Social isolation / loneliness Sleep, mood and social life Prevention Harm
why

Isolation (being alone) carried the risk (HR 1.26); loneliness (feeling alone) did not once depressive symptoms were accounted for (HR 1.04, 95% CI 0.94-1.16). That split matters, and the loneliness meta-analysis here reaches the opposite conclusion about loneliness.

 Incident dementia over a mean 11.7 years cohort study 462,619 Social isolation HR 1.26 (95% CI 1.15-1.37) for incident dementia Neurology 2022
✓ Peer-reviewed PMID 35676089
Social isolation / loneliness Sleep, mood and social life Prevention Benefit
why

Significant only for contact measured at age 60, not at 50 or 70. The authors note that keeping up contact may itself be a marker of cognitive reserve rather than a cause of it.

 Incident dementia over 28 years cohort study 10,228 HR 0.88 per SD higher social contact frequency at age 60 (95% CI 0.79-0.98) PLoS Medicine 2019
✓ Peer-reviewed PMID 31374073

How this table was built, and where it is weak →