SERUM VITAMIN-B-12 LEVELS AND INCIDENCE OF DEMENTIA IN A HEALTHY ELDERLY POPULATION - A REPORT FROM THE BRONX LONGITUDINAL AGING STUDY

OBJECTIVE: To determine whether low serum B-12 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 B-12 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 B-12 level of entire sample was 558 pg/mL. Twenty-two subjects had low B-12 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 B-12 group was 4.5% compared with 7.5% in the higher B-12 group. The mean B-12 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 B-12. Of the 3 low B-12 subjects who did become demented, none responded to monthly B-12 injections. CONCLUSION: A low B-12 level may not be a risk factor for dementia in general or Alzheimer disease in particular.