Serum vitamin B12 levels and incidence of dementia in a healthy elderly population: a report from the Bronx Longitudinal Aging Study

J Am Geriatr Soc. 1994 Sep;42(9):933-6. doi: 10.1111/j.1532-5415.1994.tb06583.x.


Objective: To determine whether low serum B12 levels are associated with an increased incidence of dementing illness.

Design: Longitudinal cohort study, 5-year follow-up.

Participants: Volunteer cohort of 410 nondemented ambulatory subjects aged 75 to 85 years.

Measurements: Annual serum B12 determinations and neuropsychological assessments including the Blessed Test of Information, Memory and Concentration (BIMC) and the Fuld Object Memory Evaluation (FOME). If subject met criteria for a major cognitive change (as defined by an increase of 4 or more points on the BIMC), a work-up that included CT, EEG, and neurologic assessment was performed. Clinical diagnoses were made according to established criteria.

Results: Mean serum B12 level of entire sample was 558 pg/mL. Twenty-two subjects had low B12 levels defined as values < 150 pg/mL. Three of these 22 subjects (13.6%) became demented, compared with 57 of 388 subjects (14.7%) with higher levels. The incidence of Alzheimer disease among the low B12 group was 4.5% compared with 7.5% in the higher B12 group. The mean B12 level at time of diagnosis in subjects who did develop Alzheimer disease was 551 pg/mL. There was no evidence of hematologic disorder among the 22 subjects with low B12. Of the 3 low B12 subjects who did become demented, none responded to monthly B12 injections.

Conclusion: A low B12 level may not be a risk factor for dementia in general or Alzheimer disease in particular.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aged
  • Aged, 80 and over*
  • Alzheimer Disease / blood
  • Dementia / blood*
  • Dementia / epidemiology
  • Humans
  • Incidence
  • Longitudinal Studies
  • New York City / epidemiology
  • Vitamin B 12 / blood*


  • Vitamin B 12