Dementia is associated with low vitamin D - many studies
Dementia 49% more likely if low vitamin D - Sept 2025
Association of vitamin D with risk of dementia : a dose-response meta-analysis of observational studies
Front Neurol . 2025 Sep 10:16:1649841. doi: 10.3389/fneur.2025.1649841
Yaping Huang 1, Yun Chen 1, Yan Wu 1, Yan Wu 1, Xinyi Dai 1, Juan Feng 1, Xia Li 1
Background: The relationship between serum vitamin D levels and dementia risk remains unclear. This meta-analysis aims to evaluate the association and dose-response relationship between vitamin D levels and dementia risk.
Methods: A systematic literature search was conducted in Cochrane Library, PubMed, and Embase up to October 2024. A total of 22 studies comprising 53,122 participants were included. Pooled relative risks (RRs) and 95% confidence intervals (CIs) were calculated using random-effects models. A dose-response meta-analysis explored linear and non-linear relationships.
Results: Participants in the lowest vitamin D category had a 49% higher risk of dementia compared to those in the highest category ( RR = 1.49 , 95% CI: 1.32-1.67; I 2 = 37.8%, p = 0.039). The dose-response analysis indicated a linear association, with each 10 nmol/L increase in vitamin D associated with a 1.2% lower dementia risk (RR = 0.988, 95% CI: 0.982-0.994; p = 0.007). Although statistically significant, the magnitude of this effect suggests limited clinical relevance at the individual level, though potential public health impact may be greater in populations with widespread deficiency. No evidence of non-linearity was observed (p for non-linearity = 0.61).
Conclusions: This meta-analysis of observational studies suggests an inverse association between serum vitamin D levels and dementia risk, with a small but consistent dose-response effect. While these findings are robust across subgroups, causality cannot be inferred from observational data. Randomized controlled trials are needed to confirm whether vitamin D supplementation can reduce dementia risk.
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13% of dementia patients have liver failure (which reduces vitamin D levels) - Jan 2024
Undiagnosed Cirrhosis and Hepatic Encephalopathy in a National Cohort of Veterans With Dementia
doi:10.1001/jamanetworkopen.2023.53965 FREE PDF Vitamin D is not mentioned once
See Vitamin D Life Overview Liver and vitamin D
Vitamin D reduced Dementia in VA by 40% - Dr. Campbell March 2023
reporting on Vitamin D supplementation and incident dementia: Effects of sex, APOE, and baseline cognitive status
which is in Vitamin D Life Dementia risks reduced by Vitamin D – March 2023
67+ Vitamin D pages contain "Dementia" in title
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Vitamin D Life - Overview Alzheimer's-Cognition and Vitamin D
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Vitamin D Life - Super-Agers also have better cognition - April 2024 perhaps due to better Blood-Brain-Barrier
Dementia 1.8X more likely if low Vitamin D - April 2022
Vitamin D and brain health: an observational and Mendelian randomization study
Am J Clin Nutr . 2022 Apr 22;nqac107. doi: 10.1093/ajcn/nqac107.
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Vitamin D deficiency as a risk factor for dementia: a systematic review and meta-analysis - 2017
BMC Geriatrics volume 17, Article number: 16 (2017)
Isolde Sommer, Ursula Griebler, Christina Kien, Stefanie Auer, Irma Klerings, Renate Hammer, Peter Holzer & Gerald Gartlehner
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Background
Sunlight exposure and high vitamin D status have been hypothesised to reduce the risk of developing dementia. The objective of our research was to determine whether lack of sunlight and hypovitaminosis D over time are associated with dementia.
Methods
We systematically searched MEDLINE (via PubMed), Cochrane Library, EMBASE, SCOPUS, Web of Science, ICONDA, and reference lists of pertinent review articles from 1990 to October 2015. We conducted random effects meta-analyses of published and unpublished data to evaluate the influence of sunlight exposure or vitamin D as a surrogate marker on dementia risk.
Results
We could not identify a single study investigating the association between sunlight exposure and dementia risk. Six cohort studies provided data on the effect of serum vitamin D concentration on dementia risk. A meta-analysis of five studies showed a higher risk for persons with serious vitamin D deficiency (<25 nmol/L or 7–28 nmol/L) compared to persons with sufficient vitamin D supply (≥50 nmol/L or 54–159 nmol/L) (point estimate 1.54; 95% CI 1.19–1.99, I2 = 20%). The strength of evidence that serious vitamin D deficiency increases the risk of developing dementia, however, is very low due to the observational nature of included studies and their lack of adjustment for residual or important confounders (e.g. ApoE ε4 genotype), as well as the indirect relationship between Vitamin D concentrations as a surrogate for sunlight exposure and dementia risk.
Conclusions
The results of this systematic review show that low vitamin D levels might contribute to the development of dementia. Further research examining the direct and indirect relationship between sunlight exposure and dementia risk is needed. Such research should involve large-scale cohort studies with homogeneous and repeated assessment of vitamin D concentrations or sunlight exposure and dementia outcomes.
Quality assessment of systematic reviews of vitamin D, cognition and dementia - 2018
BJPsych Open. 2018 Jul;4(4):238-249. doi: 10.1192/bjo.2018.32.
Aghajafari F1, Pond D2, Catzikiris N3, Cameron I4.
1 Assistant Professor, Dept of Family Medicine, Cumming School of Medicine, U. of Calgary Sunridge Family Medicine Teaching Centre, Canada.
2 Professor and Head of Department of Family Medicine, University of Newcastle, Australia.
3 Research Assistant, School of Medicine and Public Health, Faculty of Medicine, The University of Newcastle, Australia.
4 Professor, Northern Clinical School, Rehabilitation Studies Unit, Sydney Medical School, The University of Sydney, Australia.
BACKGROUND: There is conflicting evidence regarding the association of vitamin D with cognition performance and dementia.
Aims We aimed to summarise the evidence on the association of vitamin D with cognitive performance, dementia and Alzheimer disease through a qualitative assessment of available systematic reviews and meta-analyses.
METHOD: We conducted an overview of the systematic reviews of all study types with or without meta-analyses on vitamin D and either Alzheimer disease, dementia or cognitive performance up to June 2017.
RESULTS:
Eleven systematic reviews were identified, nine of which were meta-analyses with substantial heterogeneity, differing statistical methods, variable methodological quality and quality of data abstraction. A Measurement Tool to Assess Systematic Reviews checklist scores ranged from 4 to 10 out of 11, with seven reviews of 'moderate' and four of 'high' methodological quality.
Out of six meta-analyses on the association between low serum concentration of 25-hydroxyvitamin D and risk of dementia, five showed a positive association . Results of meta-analyses on the association between low serum concentration of 25-hydroxyvitamin D and memory function tests showed conflicting results.
CONCLUSIONS:
This systematic evaluation of available systematic reviews provided a clearer understanding of the potential link between low serum vitamin D concentrations and dementia. This evaluation also showed that the quality of the available evidence is not optimal because of both the low methodological quality of the reviews and low quality of the original studies. Interpretation of these systematic reviews should therefore be made with care.
VITAMIN D AND DEMENTIA - 2016
J Prev Alz Dis 2016;3(1):43-52 http://dx.doi.org/10.14283/jpad.2015.68 full text and graphics at the website
T.J. Littlejohns1,2, K. Kos2, W.E. Henley2, E. Kuźma2, D.J. Llewellyn 2 [email protected]
Clinical Trials Service Unit and Epidemiological Studies Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK;
University of Exeter Medical School, University of Exeter, Exeter, UK
Emerging evidence suggests that low vitamin D concentrations are potentially involved in the pathogenesis of dementia. This is of particular interest when considering the high prevalence of vitamin D deficiency in elderly adults and the urgent need to identify modifiable risk factors for dementia. Studies have found that vitamin D is implicated in procognitive and neuroprotective functions, including the reduction of Alzheimer’s disease hallmarks such as amyloid beta and phosphorylated tau. Cross-sectional studies have consistently found that vitamin D concentrations are significantly lower in individuals with Alzheimer’s disease and cognitive impairment compared to healthy controls. Longitudinal studies support an association between low vitamin D concentrations and an increased risk of dementia and cognitive decline. Neuroimaging studies are beginning to uncover the potential neurodegenerative and cerebrovascular mechanisms that underlie these associations such as white matter hyperintensities and enlarged ventricular volume, although there is currently a lack of longitudinal studies. In contrast to observational studies, findings from interventional studies have produced mixed results on the benefits of vitamin D supplementation on dementia and cognitive outcomes. Interpretation of the findings from these studies is hampered by several major methodological limitations, such as small sample sizes, inadequate doses and inclusion of participants unlikely to benefit from vitamin D supplementation. There is a need for large double-blind randomised-control trials investigating whether vitamin D supplementation can halt or delay the risk of dementia-related outcomes in individuals with low vitamin D concentrations.
How to Communicate With People Suffering From Dementia - April 2022 - nothing about Vitamin D
- "Anne Basting says the key is to not ask questions that force those with Alzheimer’s to remember facts. Instead, focus on creative and emotional communication."
Dementia is also associated with Magnesium
Note: increased Magnesium increases the vitamin D in the blood and cells, e.g. brain cells
People getting 550 mg ( vs 330 mg) of magnesium in diet had brains which were 1 year younger at age 55 MDEdge April 2023 study
Low Serum Magnesium is Associated with Incident Dementia in the ARIC-NCS Cohort - Oct 2020 1.2X 📄 PDF
Serum magnesium is associated with the risk of dementia - 2017 BOTH high and low Mg 📄 PDF via Sci-Hub
Association between magnesium intake and cognition in US older adults: National Health and Nutrition Examination Survey (NHANES) 2011 to 2014 - Feb 2022 📄 PDF
Vitamin D Life - Dementia less likely with increased levels of Magnesium etc.
Dementia risk increased 1.5X to 1.9X: depends on type of laxative used - Feb 2023
Regular laxative use tied to increased dementia risk MDEdge
Tiny brain hemorrhages were found in 17% of people who've had a concussion—increased dementia risk - Sept 2024
Neuroimaging and Clinical Findings in Healthy Middle-Aged Adults With Mild Traumatic Brain Injury in the PREVENT Dementia Study
JAMA Netw Open. 2024;7(8):e2426774. doi:FREE PDF
32,000 hits for the search: dementia (latitude OR sunshine)
Associations between natural sunlight exposure and brain structural markers: a prospective study in the UK Biobank -2023 https://doi.org/10.1101/2023.10.12.23296944 FREE PDF
Time spent in outdoor light is associated with the risk of dementia: a prospective cohort study of 362094 participants - April 2022 https://doi.org/10.1186/s12916-022-02331-2 FREE PDF
- 1.3 increased risk if <1 hour a day of sun