Table 1.

Characteristics (unadjusted) of cycle 2 clinical evaluation sample (n=842) and of the analytic sample of CHAP subjects (n=121) and as stratified by race^a

Abbreviations: CHAP=Chicago Health and Aging Project; MMA=methylmalonic acid; NA=not available; WMHV=white matter hyperintensity volume.

^aValues expressed as mean ± SD or %.

^bBoth measures are expressed in proportion to total cranial volume to correct for head size and multiplied by 100. WMHV is natural log transformed to create a normal distribution.

^cVitamin B12 determinations are routinely performed for all participants, but the additional markers for vitamin B12 are not. Thus, these values reflect those of the 666 clinically evaluated subjects with available blood for further analyses.

^dProbable vitamin B12 deficiency is defined as described by Allen and coworkers^11,12 using the following set of criteria: serum vitamin B12 < 258 pmol/L (or 343 pg/mL) and serum methylmalonic acid concentration >271 nmol/L, and serum MMA >2-methylcitric acid concentration.