Mangialasche F, Solomon A, Kåreholt I, Hooshmand B, Cecchetti R, Fratiglioni L, Soininen H, Laatikainen T, Mecocci P, Kivipelto M. (2013) Exp Gerontol. 48(12): 1428-35. doi: 10.1016/j.exger.2013.09.006. Epub 2013 Oct 7.
Vitamin E includes eight natural antioxidant compounds (four tocopherols and four tocotrienols), but α-tocopherol has been the main focus of investigation in studies of cognitive impairment and Alzheimer's disease.
To investigate the association between serum levels of tocopherols and tocotrienols, markers of vitamin E oxidative/nitrosative damage (α-tocopherylquinone, 5-nitro-γ-tocopherol) and incidence of cognitive impairment in a population-based study.
A sample of 140 non-cognitively impaired elderly subjects derived from the Cardiovascular Risk Factors, Aging, and Dementia (CAIDE) study was followed-up for 8years to detect cognitive impairment, defined as development of mild cognitive impairment (MCI) or Alzheimer's dementia. The association between baseline serum vitamin E and cognitive impairment was analyzed with multiple logistic regression after adjusting for several confounders.
The risk of cognitive impairment was lower in subjects in the middle tertile of the γ-tocopherol/cholesterol ratio than in those in the lowest tertile: the multiadjusted odds ratio (OR) with 95% confidence interval (CI) was 0.27 (0.10-0.78). Higher incidence of cognitive impairment was found in the middle (OR (95% CI): 3.41 (1.29-9.06)) and highest (OR (95% CI): 2.89 (1.05-7.97)) tertiles of the 5-NO2-γ-tocopherol/γ-tocopherol ratio.
Analyses of absolute serum levels of vitamin E showed lower risk of cognitive impairment in subjects with higher levels of γ-tocopherol, β-tocotrienol, and total tocotrienols.
Elevated levels of tocopherol and tocotrienol forms are associated with reduced risk of cognitive impairment in older adults. The association is modulated by concurrent cholesterol concentration.
Various vitamin E forms might play a role in cognitive impairment, and their evaluation can provide a more accurate measure of vitamin E status in humans.
For an accessible news summary of this research, see:
This research builds on earlier work by the same team, showing associations between both Mild Cognitive Impairment and Alzheimer's disease and blood measures of Vitamin E (again, assessing all forms, as well as markers of Vitamin E damage). See:
Mangialasche et al 2012 - Tocopherols and tocotrienols plasma levels are associated with cognitive impairment