Plasma tocopherols and risk of cognitive impairment in an elderly Italian cohort.
BACKGROUND
Evidence that vitamin E may preserve cognitive function in elderly subjects is conflicting. The most abundant and most investigated form of vitamin E in humans is alpha-tocopherol, but other antioxidant tocopherols (beta, gamma, and delta) exist in nature.


OBJECTIVE
We aimed to investigate plasma concentrations of the natural tocopherols and the tocopherol oxidation markers alpha-tocopherylquinone (alphaTQ) and 5-nitro-gamma-tocopherol (5NGT) in relation to cognitive function in the elderly.


METHODS
Baseline plasma tocopherols and their oxidation markers were measured in 761 elderly Italian subjects from a population-based cohort assessed in 1999-2000 for mild cognitive impairment (MCI) and dementia. In 2003-2004, information about cognitive status was collected for 615 of the 666 subjects without baseline cognitive impairment. Tocopherols and oxidation markers were analyzed as plasma absolute values divided by serum total cholesterol because lipids affect their blood availability. Analyses were adjusted for sociodemographic, genetic, lifestyle, and medical confounders.


RESULTS
Compared with the corresponding lowest tertile, the risk of prevalent dementia was higher for the highest tertile of delta-tocopherol/cholesterol [odds ratio (OR): 3.87; 95% CI: 1.46, 10.27] and alphaTQ/cholesterol (4.02; 1.45, 11.14), but the risk of incident dementia was not directly associated with plasma vitamin E metabolites. A U-shaped association, with lower risk for intermediate tertiles, was found for prevalent MCI with 5NGT/cholesterol (0.39; 0.17, 0.91) and for incident dementia with gamma-tocopherol/cholesterol (hazard ratio: 0.42; 95% CI: 0.22, 0.84).


CONCLUSIONS
Plasma concentrations of some non-alpha-tocopherol forms of vitamin E are associated with cognitive impairment in elderly people. However, the associations depend on concurrent cholesterol concentration and need further investigation.
Ravaglia
Giovanni
G
Department of Internal Medicine, Cardioangiology, and Hepatology, University Hospital Sant'Orsola-Malpighi, University of Bologna, Bologna, Italy. ravaglia@med.unibo.it
Forti
Paola
P
Lucicesare
Anna
A
Pisacane
Nicoletta
N
Rietti
Elisa
E
Mangialasche
Francesca
F
Cecchetti
Roberta
R
Patterson
Christopher
C
Mecocci
Patrizia
P
D000368:Aged; D000369:Aged, 80 and over; D000975:Antioxidants / Q000378:metabolism; D002784:Cholesterol / Q000097:blood*; D003072:Cognition Disorders / Q000097:blood / Q000150:complications / Q000453:epidemiology*; D015331:Cohort Studies; D016001:Confidence Intervals; D003704:Dementia / Q000097:blood* / Q000453:epidemiology* / Q000209:etiology; D018450:Disease Progression; D005260:Female; D006801:Humans; D015994:Incidence; D007558:Italy / Q000453:epidemiology; D008297:Male; D015999:Multivariate Analysis; D016017:Odds Ratio; D015995:Prevalence; D012307:Risk Factors; D024505:Tocopherols / Q000097:blood*; D014810:Vitamin E / Q000031:analogs & derivatives / Q000097:blood*
D000975:Antioxidants; D014810:Vitamin E; D002784:Cholesterol; D024505:Tocopherols