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Prevention of dementia: a role for B vitamins?

Abstract

Dementia has reached epidemic proportions, with an estimated 4.6 million new cases worldwide each year. With an aging world population the prevalence of dementia will increase dramatically in the next few decades. Of the predicted 114 million who will have dementia in 2050 about three-quarters will live in the less-developed regions. Although strongly age -related, dementia is not an inevitable part of aging but is a true disease caused by exposure to several genetic and non-genetic risk factors. Prevention will be possible when the non genetic risk factors have been identified. Apart from age, more than 20 non-genetic risk factors have been postulated but very few have been established by randomised intervention studies. Elevated blood concentrations of total homocysteine and low-normal concentrations of B vitamins (folate, vitamins B-12 and B-6) are candidate risk factors for both Alzheimer's disease and vascular dementia. A review of the literature up to the end of 2005 shows the following. Seventy seven cross-sectional studies on > 34,000 subjects and 33 prospective studies on > 12,000 subjects have shown associations between cognitive deficit or dementia and homocysteine and/or B vitamins. Biologically plausible mechanisms have been proposed to account for these associations, including atrophy of the cerebral cortex, but a definite causal pathway has yet to be shown. Raised plasma total homocysteine is a strong prognostic marker of future cognitive decline, and is common in world populations. Low-normal concentrations of the B vitamins, the main determinant of homocysteine concentrations, are also common and occur in particularly vulnerable sections of the population, such as infants and the elderly. Large-scale randomised trials of homocysteine-lowering B vitamins are needed to see if a proportion of dementia in the world can be prevented.

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  • Publisher Full Text
  • Authors+Show Affiliations

    Oxford Project to Investigate Memory and Aging (OPTIMA), University of Oxford, UK. david.smith@pharm.ox.ac.uk

    Source

    Nutrition and health 18:3 2006 pg 225-6

    MeSH

    Aging
    Dementia
    Environment
    Genetic Predisposition to Disease
    Humans
    Risk Factors
    Vitamin B Complex

    Pub Type(s)

    Journal Article
    Review

    Language

    eng

    PubMed ID

    17180867

    Citation

    Smith, A David. "Prevention of Dementia: a Role for B Vitamins?" Nutrition and Health, vol. 18, no. 3, 2006, pp. 225-6.
    Smith AD. Prevention of dementia: a role for B vitamins? Nutr Health. 2006;18(3):225-6.
    Smith, A. D. (2006). Prevention of dementia: a role for B vitamins? Nutrition and Health, 18(3), pp. 225-6.
    Smith AD. Prevention of Dementia: a Role for B Vitamins. Nutr Health. 2006;18(3):225-6. PubMed PMID: 17180867.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Prevention of dementia: a role for B vitamins? A1 - Smith,A David, PY - 2006/12/22/pubmed PY - 2007/2/9/medline PY - 2006/12/22/entrez SP - 225 EP - 6 JF - Nutrition and health JO - Nutr Health VL - 18 IS - 3 N2 - Dementia has reached epidemic proportions, with an estimated 4.6 million new cases worldwide each year. With an aging world population the prevalence of dementia will increase dramatically in the next few decades. Of the predicted 114 million who will have dementia in 2050 about three-quarters will live in the less-developed regions. Although strongly age -related, dementia is not an inevitable part of aging but is a true disease caused by exposure to several genetic and non-genetic risk factors. Prevention will be possible when the non genetic risk factors have been identified. Apart from age, more than 20 non-genetic risk factors have been postulated but very few have been established by randomised intervention studies. Elevated blood concentrations of total homocysteine and low-normal concentrations of B vitamins (folate, vitamins B-12 and B-6) are candidate risk factors for both Alzheimer's disease and vascular dementia. A review of the literature up to the end of 2005 shows the following. Seventy seven cross-sectional studies on > 34,000 subjects and 33 prospective studies on > 12,000 subjects have shown associations between cognitive deficit or dementia and homocysteine and/or B vitamins. Biologically plausible mechanisms have been proposed to account for these associations, including atrophy of the cerebral cortex, but a definite causal pathway has yet to be shown. Raised plasma total homocysteine is a strong prognostic marker of future cognitive decline, and is common in world populations. Low-normal concentrations of the B vitamins, the main determinant of homocysteine concentrations, are also common and occur in particularly vulnerable sections of the population, such as infants and the elderly. Large-scale randomised trials of homocysteine-lowering B vitamins are needed to see if a proportion of dementia in the world can be prevented. SN - 0260-1060 UR - https://www.unboundmedicine.com/medline/citation/17180867/Prevention_of_dementia:_a_role_for_B_vitamins L2 - http://journals.sagepub.com/doi/full/10.1177/026010600601800304?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -