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Observational epidemiological surveys (WG 3) page 75
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In one American study (Mendelshon et al., 1998), cognitive function (15 tests measuring
performance in various domains known to be affected in dementia) was related to the self-
reported use of supplements (defined as any over-the-counter medication containing vitamin
A, C or E, or β-carotene, or Zn or Se) in 1059 rural non-institutionalised subjects. After
adjustment for confounders, there were no significant differences in cognitive test
performance between antioxidant users and non-users. The other American study (Perkins et
al., 1999) explored memory performance in an elderly multiethnic population sample (4 809
>60 years old). The lipophile plasma antioxidants were expressed as ratios of cholesterol. A
low ratio vitamin E/cholesterol (< 4.8) was associated with an increased OR: 2.09 (1.02-4.26),
whereas there was no association with plasma vitamin C, nor β-carotene/cholesterol ratio. In
the Rotterdam study, the data were derived from 5182 community participants (Jama et al.,
1996). Cognitive function was tested with the 30-point Mini-mental State Examination at
baseline when dietary intake was assessed through a 170 item semi-quantitative validated
food questionnaire, which was checked and verified at the visit to the research center. After
controlling for confounders, the OR for cognitive impairement was 1.90 (CI: 1.17-3.08; trend
44.9mg/day, after adjustment for all confounding
factors. The authors quoted two previous studies showing comparable results. It should be
noted that in this study vitamin C intake was very low, whereas in the Rotterdam study (Jama
et al., 1996), the vitamin C intake is quite normal (from < 77mg/day to ≥ 160mg/day).
The Australian prospective study (Paleologos et al., 1998) corroborated the British study. In
117 subjects recruited in a retirement community, vitamin C intake was assessed with a self-
administered food frequency questionnaire, and validated four weeks later by a repeat food
frequency questionnaire. Assessment of cognitive function was done four years later by the
Mini-mental State Examination. The OR for cognitive impairement was 0.32 (CI: 0.18- 0.88;
trend p=0.05) for 706mg/day versus < 62mg/day.