Vitamin B₁₂ status, cognitive decline and dementia: a systematic review of prospective cohort studies

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#aged #aged-80-and-over #biomarkers #cognition #cognition-disorders

Vitamin B₁₂ status, cognitive decline and dementia: a systematic review of prospective cohort studies

O'Leary et al., 2012 | Br J Nutr | Systematic Review

Citation

O'Leary Fiona, Allman-Farinelli Margaret, Samman Samir. Vitamin B₁₂ status, cognitive decline and dementia: a systematic review of prospective cohort studies. Br J Nutr. 2012-Dec-14;108(11):1948-61. doi:10.1017/S0007114512004175

Abstract

Poor vitamin B₁₂ status may lead to the development of cognitive decline and dementia but there is a large variation in the quality, design of and results reported from these investigations. We have undertaken a systematic review of the evidence for the association between vitamin B₁₂ status and cognitive decline in older adults. A database search of the literature to 2011 was undertaken, using keywords related to vitamin B₁₂ and cognition. All prospective cohort studies assessing the association of serum vitamin B₁₂ or biomarkers were included. Quality assessment and extraction of the data were undertaken by two researchers. The quality assessment tool assigns a positive, neutral or negative rating. Of 3772 published articles, thirty-five cohort studies (n 14 325 subjects) were identified and evaluated. No association between serum vitamin B₁₂ concentrations and cognitive decline or dementia was found. However, four studies that used newer biomarkers of vitamin B₁₂ status (methylmalonic acid and holotranscobalamin (holoTC)) showed associations between poor vitamin B₁₂ status and the increased risk of cognitive decline or dementia diagnosis. In general, the studies were of reasonable quality (twenty-one positive, ten neutral and four negative quality) but of short duration and inadequate subject numbers to determine whether an effect exists. Future studies should be of adequate duration (at least 6 years), recruit subjects from the seventh decade, choose markers of vitamin B₁₂ status with adequate specificity such as holoTC and/or methylmalonic acid and employ standardised neurocognitive assessment tools and not screening tests in order to ascertain any relationship between vitamin B₁₂ status and cognitive decline.

Key Findings

Future studies should be of adequate duration (at least 6 years), recruit subjects from the seventh decade, choose markers of vitamin B₁₂ status with adequate specificity such as holoTC and/or methylmalonic acid and employ standardised neurocognitive assessment tools and not screening tests in order to ascertain any relationship between vitamin B₁₂ status and cognitive decline.

Outcomes Measured

  • Requires manual extraction

Population

Field Value
Population older adults
Sample Size 325
Age Range See abstract
Condition cognitive

MeSH Terms

  • Aged
  • Aged, 80 and over
  • Biomarkers
  • Cognition
  • Cognition Disorders
  • Cognitive Dysfunction
  • Dementia
  • Disease Progression
  • Female
  • Humans
  • Male
  • Methylmalonic Acid
  • Middle Aged
  • Nutritional Status
  • Transcobalamins
  • Vitamin B 12
  • Vitamin B 12 Deficiency

Evidence Classification

  • Level: Systematic Review
  • Publication Types: Journal Article, Systematic Review
  • Vertical: vitamin-b12-cognition

Provenance

Source extracted via PubMed E-utilities API on 2026-04-09