Results of this study indicate that folate deficiency or possible deficiency increases the risk for Alzheimer’s Disease, while sufficient intake of folate is a protective factor against Alzheimer’s (Zhang X, et al., 2021).
The following researchers showed that high-dose of B-vitamin treatment (folic acid 0.8 mg, vitamin B6 20 mg, vitamin B12 0.5 mg) slowed shrinkage of the whole brain volume over 2 years (Douaud G, et al., 2013).
The same researchers demonstrated that B-vitamin treatment reduces, by as much as seven-fold, the cerebral atrophy in those gray matter regions of the brain specifically vulnerable to the Alzheimer’s Disease process.
Higher homocysteine levels are associated with faster gray matter atrophy but can be prevented by B-vitamin treatment. Homocysteine is an amino acid which is toxic at elevated levels.
When taking B-vitamins be sure to take the metabolite of folic acid, 5-methyltetrahydofolate, since quite a few people have a genetic predisposition making it difficult to metabolize folic acid.
References:
Gwenaëlle Douaud 1, Helga Refsum, Celeste A de Jager, Robin Jacoby, Thomas E Nichols, Stephen M Smith, A David Smith, Preventing Alzheimer's disease-related gray matter atrophy by B-vitamin treatment, Proc Natl Acad Sci U S A. 2013 Jun 4;110(23):9523-8.
Xiaohong Zhang, Guangyi Bao, Debiao Liu, Yu Yang, Xuezhi Li, Gaomei Cai, Yan Liu, Yili Wu, The Association Between Folate and Alzheimer's Disease: A Systematic Review and Meta-Analysis, Front Neurosci. 2021 Apr 14;15:661198.