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.

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. DESIGN: 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