Design: The Newcastle 85+ Study was a prospective longitudinal study of people 85 years old and followed over 5 years in Northeast England.
Setting: Community-dwelling and institutionalized.
Participants: The analytical sample included 765 very old participants with 1-C metabolism biomarkers and cognitive measures.
Measurements: Global cognition was measured by the Standardized Mini-Mental State Examination (SMMSE) at baseline, and at 3 and 5 years of follow-up and, attention-specific cognition with the Cognitive Drug Research (CDR) System at baseline, and at 1.5 and 3.0 years of follow-up. Baseline red blood cell folate (RBC folate), plasma vitamin B12, and total homocysteine (tHcy) concentrations were determined by immunoassay. Linear mixed models were used to estimate the associations between quartiles of 1-C metabolism biomarkers and cognition over 3 (CDR) and 5 years (SMMSE).
Results: Compared with participants in the lowest quartile of RBC folate concentrations (1280 nmol/L) had 1 more point on the SMMSE at baseline (β = +1.02, SE = 0.43, P = .02). Those in quartile 4 of tHcy (>21.4 μmol/L) had 1 point less in the SMMSE at baseline than those in the lowest quartile (<13.5 μmol/L) (β = −1.05, SE = 0.46, P = .02). Plasma vitamin B12 was not predictive of global or attention-specific cognition at baseline and at follow-up. None of the 1-C metabolism biomarkers except tHcy was associated with the rate of decline in attention scores over 3 years.
RBC folate and tHcy, but not plasma vitamin B12, were associated with better global cognition in the very old at baseline but were not predictive of rate of decline over 5 years.
|Journal||Journal of the American Medical Directors Association|
|Early online date||21 Jun 2017|
|Publication status||Published - 1 Sep 2017|