Association between antioxidant nutritional indicators and the incidence of dementia: results from the PAQUID prospective cohort study.

OBJECTIVE

To analyse the relation between antioxidant vitamins A, E, and malondialdehyde (MDA) lipoperoxidation product plasma concentrations with incident dementia.

DESIGN

: A nested case-control within the PAQUID (Personnes Agées QUID) cohort.

SETTING

The PAQUID population-based prospective cohort in southwestern France.

SUBJECTS

Among 626 subjects with blood collection at baseline, 46 developed a dementia during the follow-up and were considered to be cases. Each case was matched (on age and sex) to three controls.

RESULTS

Plasma vitamin E concentrations were lower among cases (mean value at 22.62 micromol/l (s.d.: 7.38) vs 24.99 (s.d.: 6.73 among controls). The same trend was observed for vitamin A concentrations, but the difference was not significant. On the contrary, MDA concentrations tended to be higher (mean value 1.35 micromol/l (s.d.: 0.53) vs 1.23 (s.d.: 0.44)) among cases. In logistic regression models, plasma values were split into tertiles. Adjusted for confounders, the risk of dementia was significantly increased in the lowest vitamin E tertile (< or =21.0 micromol/l) (OR=3.12, P=0.033) compared to the highest one (> or =25.5 micromol/l). The risk of Alzheimer's disease was also increased, with borderline significance (OR=3.06, P=0.053). Risks associated with vitamin A were nonsignificant. Similarly, there was a trend to an increased risk of dementia in the highest tertile of MDA (OR=1.67, P=0.31).

CONCLUSIONS

These results suggest that subjects with low plasma vitamin E concentrations are at a higher risk of developing a dementia in subsequent years.