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J Am Geriatr Soc. 1994 Sep;42(9):933-6.

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

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Department of Neurology, Albert Einstein College of Medicine, Bronx, New York 10461.



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


Longitudinal cohort study, 5-year follow-up.


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


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.


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.


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

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