Current Understanding: |
The evidence from observational epidemiologic studies suggests that higher levels of plasma total homocysteine (tHcy) may be associated with an increased risk of incident Alzheimer's disease (AD). This body of findings is consistent with findings from related studies of cognitive decline, of brain imaging, and of genetic polymorphisms predisposing individuals to hyperhomocysteinemia. Recent trials of the tHcy-lowering vitamins—B6, B12, and folate, however, have had mixed, predominantly null results. Further research will be required to know whether supplementation with B vitamins starting in midlife, when it could prevent chronic elevation of homocysteine over a longer span, would provide greater benefit. For a review of the putative mechanisms by which homocysteine may influence AD risk and detailed commentary on interpreting the findings below in a broader context, please view the Discussion. |
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