Background: Previous reports have shown elevated plasma total homocysteine (tHcy) levels in elderly person with impaired cognition.
Objective: To study the association between cognitive status and plasma tHcy levels in centenarians.
Design: Cross-sectional survey.
Setting: Centenarians living in two northern Italian provinces.
Participants: Thirteen cognitively normal centenarians, ten cognitively impaired not-demented centenarians, and 34 demented centenarians with a clinical diagnosis of Alzheimer's disease (AD).
Measurements: Blood levels of homocysteine's biological determinants vitamin B12, folate, and vitamin B6.
Results: Elevated plasma tHcy levels (>17 micromol/l) were common in the general population (77% of normal centenarians, 100% of cognitively impaired not-demented centenarians, 82% of AD centenarians). Demented centenarians had the lowest folate serum levels. Low or borderline vitamin B12 serum levels (<221 pmol/l) and low vitamin B6 plasma levels (<11.7 nmol/l) were found in 33 and 66% of all centenarians independently of cognitive status. Among demented centenarians only plasma tHcy correlated inversely with both serum vitamin B12 and folate. No significant difference was found for plasma tHcy levels among the three diagnostic groups, even after adjusting for B vitamin levels.
Conclusions: Hyperhomocysteinemia is very common among centenarians, probably due to vitamin deficiencies, but does not seem to be associated with cognitive impairment.