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Table 3 Summary of findings for influence of sunlight exposure on risk of dementia

From: Vitamin D deficiency as a risk factor for dementia: a systematic review and meta-analysis

Population: General population aged between 54 and 85.3 years (median/mean)
Settings: Health examinations, geriatric hospitals
Exposure/Risk: Vitamin D deficiency
Comparison: No vitamin D deficiency (reference group)
Outcomes Comparative risk (95% CI) and narrative results Relative effect (95% CI) Number of participants (number of studies) Quality of evidence (GRADE) Comments
No exposure (no vitamin D deficiency) Exposure (vitamin D deficiency)
Incidence of dementia (Results meta-analysis) Follow-up:18.03 years (weighted mean) Study population (≥50 nmol/L or ≥ 54–159 nmol/L) (<25 nmol/L or 7–28 nmol/L) Point (raw) 1.54 (1.19 to 1.99) 18 639 subjects (5 studies) Very lowa,b
Incidence of dementia (Narrative results) Follow-up: 7 years Study population (≥25 nmol/L) (<25 nmol/L) OR 19.57 (1.11 to 343.69) 40 subjects (1 study)
  1. Abbreviations: CI confidence interval, nmol/L nanomoles per Litre, OR odds ratio
  2. aRisk of bias: Adjustment for confounders varies across study groups, Apo E ε4 genoytpe only considered in one study
  3. bIndirectness: no study investigated the direct relationship between solar radiation and dementia, vitamin D is a surrogate parameter