One-Carbon Metabolism Biomarkers and Cognitive Decline in the Very Old: The Newcastle 85+ Study.
Nuno Mendonça, Antoneta Granic, John C Mathers and 5 others
PMID 28647580WHAT IT FOUND
In people aged 85, higher red blood cell folate and lower homocysteine at baseline were linked to better global cognitive screening scores, but neither predicted global decline over 3 to 5 years.
Vitamin B12 showed no association.
Key findings
01In adjusted models, participants in the highest red blood cell folate quartile scored 1 more point on the SMMSE at baseline than those in the lowest quartile.
02Participants in the highest homocysteine quartile scored 1 point less on the SMMSE at baseline than those in the lowest quartile.
03Red blood cell folate, plasma vitamin B12, and homocysteine were not significantly associated with the rate of global cognitive decline.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study was observational, so it cannot show that folate, vitamin B12, or homocysteine caused cognitive decline. Biomarkers were measured only at baseline, so they may not reflect status later in follow-up. Participants lost to follow-up were more likely to have higher homocysteine, more cognitive impairment, dementia or Alzheimer disease, cardiovascular disease, diabetes, and institutional living, which may have diluted the decline results. The SMMSE has a ceiling effect at 30 points, so subtle cognitive decline may not be captured. The plasma vitamin B12 assay measured total vitamin B12, including a large inert fraction, so it may not reflect active vitamin status. Reverse causality cannot be fully excluded for the baseline associations. Follow-up was 3 years for attention and 5 years for global cognition, which may be too short to detect biomarker effects.
The easy way to misread this
Do not conclude that changing folate, vitamin B12, or homocysteine will slow cognitive decline. This was an observational study of baseline biomarkers, and the biomarkers were not predictive of the rate of global cognitive decline. The associations could also reflect reverse causality.