|
| First author, year | Inclusion criteria | Outcomes | Assessment of dementia | Number of articles included | Number of patients | Design of the included articles | Main conclusion |
|
| Goodwill, 2017 [31] | Longitudinal, cross-sectional, and interventional studies.
Data of serum 25OHD in healthy adults and its correlation with CI and dementia | Dementia and MCI | Cognitive function tests (e.g., MMSE, Boston naming test, Stroop test, Raven’s progressive matrices, clock drawing; block) | 41 studies | 9,556 | Cross-sectional (n = 20)
Longitudinal (n = 18)
Interventional (n = 3) | Significant association in cross-sectional studies (95% CI I1.09 to 1.23) and weak association in longitudinal studies.
No benefit with vitamin D supplementation (95% CI −0.05 to 0.46) |
|
| Sommer, 2017 [3] | Prospective and retrospective studies with data on serum vitamin D and dementia | Dementia: Alzheimer’s disease vascular, frontotemporal, Lewy body | Diagnostic criteria (e.g., ICD10, DSM4, NINCDS-ADRDA) | 6 studies | 18,933 | Prospective (n = 5),
Retrospective (n = 1) | Low evidence of vitamin D deficiency increasing the risk of dementia (95% CI 1.19 to 1.99) |
|
| Kuzma, 2016 [32] | Prospective studies with data on serum 25OHD and subsequent development of dementia, visual and verbal memory loss | Dementia,
Visual and verbal memory | Diagnostic criteria (e.g., NINCDS-ADRDA criteria).
Cognitive function tests (MMSE, Benton visual retention test, Reys auditory verbal learning test) | 2 studies | 1,291 | Prospective studies (n = 2) | Those moderately and severely deficient individuals with serum 25(OH)D changed (95% CI: −0.06 to 0.01) and (95% CI: −0.19 to −0.02) per year, respectively, in visual memory compared to those sufficient serum 25(OH)D were associated with a mean change of 0.01 SD (95% CI: −0.01 to 0.02) and (95% CI: −0.04 to 0.02) per year, respectively, in verbal memory compared to sufficiency |
|
| Shen, 2015 [33] | Data on 25(OH)D concentration and Alzheimer’s disease or dementia | Alzheimer’s disease and dementia | Diagnostic criteria (e.g., ICD-10, DSM- 4NINCDS-ADRDA criteria) | Alzheimer’s disease: 5 studies, 5 studies
Dementia: 5 studies, 4 studies | Alzheimer’s disease: 10,019 Dementia: 5,073 | Alzheimer’s disease: cross-sectional (n = 1), prospective (n = 4)
Dementia: cross-sectional (n = 3), prospective (n = 2) | Lower 25(OH)D status is associated with increased risk of developing AD and dementia (OR = 1.63, 95% CI 1.01–1.40) |
|
| Lopes da Silva, 2014 [34] | Data on any type of plasma nutrient status and Alzheimer’s disease | Alzheimer’s disease | Diagnostic criteria (e.g., NINCDS-ADRDA, DSM III or IV) | 5 studies | 865 | Case-control (n = 5) | No association between low levels of 25(OH)D and Alzheimer’s disease (95% CI −12.11 to 0.58) |
|
| Annweiler, 2013 [30] | Any type of observational study, data on 25(OH)D and cognition | Memory and executive dysfunction | Cognitive function tests (e.g., word list recall, serial digit recall frontal assessment battery, TMT, DST) | 17 studies | 39,975 | Cross-sectional (n = 11), prospective (n = 1) | Low serum 25(OH)D concentration found in AD when compared to controls.
No association found in longitudinal study and inconsistencies in results seen with 3 case control studies (95% CI 0.26–2.56) |
|
| van der Schaft, 2013 [35] | Observational studies with data on vitamin D (serum concentration or dietary intake and cognition) | Cognition | Cognitive function tests (e.g., MMSE, TMT, DST, n-back test, block design test) | 8 studies | 59,576 | Cross-sectional (n = 25), prospective (n = 6) | Low serum 25(OH)D was associated with higher frequency of dementia on follow-up of 4–7 years |
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