title: Vitamin B-12 status and neurologic function in older people: a cross-sectional analysis of baseline trial data from the Older People and Enhanced Neurological Function (OPEN) study.
abstract: BACKGROUND
  Aging is associated with a progressive decline in vitamin B-12 status. Overt vitamin B-12 deficiency causes neurologic disturbances in peripheral and central motor and sensory systems, but the public health impact for neurologic disease of moderately low vitamin B-12 status in older people is unclear. Evidence from observational studies is limited by heterogeneity in the definition of vitamin B-12 status and imprecise measures of nerve function.
  
  
  OBJECTIVE
  We aimed to determine whether vitamin B-12 status is associated with electrophysiologic indexes of peripheral or central neurologic function in asymptomatic older people with moderately low vitamin B-12 status.
  
  
  METHODS
  We used a cross-sectional analysis of baseline data from the Older People and Enhanced Neurological Function study conducted in Southeast England. This trial investigated the effectiveness of vitamin B-12 supplementation on electrophysiologic indexes of neurologic function in asymptomatic older people (mean age: 80 y) with moderately low vitamin B-12 status (serum vitamin B-12 concentrations ≥107 and <210 pmol/L without anemia, n = 201). Vitamin B-12 status was assessed with the use of total vitamin B-12, holotranscobalamin, and a composite indicator of vitamin B-12 status (cB-12). Electrophysiologic measures of sensory and motor components of peripheral and central nerve function were assessed in all participants by a single observer.
  
  
  RESULTS
  In multivariate models, there was no evidence of an association of vitamin B-12, holotranscobalamin, or cB-12 with any nerve conduction outcome. There was also no evidence of an association of vitamin B-12 status with clinical markers of neurologic function.
  
  
  CONCLUSIONS
  This secondary analysis of high-quality trial data did not show any association of any measure of vitamin B-12 status with either peripheral or central neurologic function or any clinical markers of neurologic function in older people with moderately low vitamin B-12 status. The results of this study are unlikely to be generalizable to a less healthy older population with more severe vitamin B-12 deficiency. This trial was registered at www.controlled-trials.com as ISRCTN54195799.
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, United Kingdom;
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Miles
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, United Kingdom;
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Allen
authors.affiliation: Department of Clinical Neurosciences, King's College, London, United Kingdom; and.
authors.forename: Kerry
authors.initials: K
authors.lastname: Mills
authors.affiliation: Clinical Trial Service Unit & Epidemiological Studies Unit, University of Oxford, Oxford, United Kingdom.
authors.forename: Robert
authors.initials: R
authors.lastname: Clarke
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, United Kingdom;
authors.forename: Ricardo
authors.initials: R
authors.lastname: Uauy
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, United Kingdom; alan.dangour@lshtm.ac.uk.
authors.forename: Alan D
authors.identifier: http://orcid.org/0000-0001-6908-1273
authors.initials: AD
authors.lastname: Dangour
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D058070:Asymptomatic Diseases / Q000453:epidemiology; D015415:Biomarkers / Q000097:blood; D002493:Central Nervous System Diseases / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control; D015986:Confounding Factors, Epidemiologic; D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D004311:Double-Blind Method; D058620:Elder Nutritional Physiological Phenomena; D055724:Electrophysiological Phenomena; D004739:England / Q000453:epidemiology; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D009431:Neural Conduction; D009460:Neurologic Examination; D009752:Nutritional Status; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control; D012720:Severity of Illness Index; D014805:Vitamin B 12 / Q000627:therapeutic use; D014806:Vitamin B 12 Deficiency / Q000097:blood / Q000178:diet therapy / Q000453:epidemiology / Q000503:physiopathology*
chemical_list: D015415:Biomarkers; D014805:Vitamin B 12
keywords: central nerve conduction; neurologic; older people; peripheral conduction; vitamin B-12