The Association of Antioxidants and Cognition
The authors examined long-term antioxidant intake in relation to cognitive decline among older women. Beginning in 1980, Nurses' Health Study (NHS) participants completed dietary assessments every 4 years; in 1995–2001, 16,010 participants aged ≥70 years completed initial cognitive assessments, which were repeated 3 times at 2-year intervals. Long-term antioxidant intake was averaged from 1980 through the time of initial cognitive interviews. Multivariable-adjusted linear regression was used to estimate mean differences in rates of cognitive decline across categories of vitamin E, vitamin C, and carotenoid intake; statistical tests were 2-sided. No associations were evident for vitamin E or total carotenoid intake and cognitive decline (e.g., after multivariable adjustment, P-trend = 0.44 and P-trend = 0.51, respectively, for a global composite score averaging all 6 cognitive tests), although higher lycopene intake and lower vitamin C intake were related to slower cognitive decline. In alternative analyses of overall cognitive status at older ages (averaging all 4 cognitive assessments), results for vitamins E and C were generally null, but higher carotenoid intake was related to better cognition. Overall, long-term vitamin E and C intakes were not consistently related to cognition, although greater consumption of carotenoids may have cognitive benefits in older adults.
Experimental data indicate that oxidative stress plays an important role in the development of cognitive impairment and Alzheimer's disease, but epidemiologic studies have produced conflicting results on the association between antioxidant vitamins and cognition in older adults. In particular, several large clinical trials of vitamin E, vitamin C, and beta-carotene supplements have shown little effect on cognitive function, with follow-up periods of 3–7 years. However, 1 trial suggested that long-term supplementation with beta-carotene, over approximately 18 years, can confer cognitive benefits, and an additional analysis by our research group indicated that long-term exposure to vitamin E supplements might be associated with cognitive health in the Nurses' Health Study (NHS). These findings are consistent with the prevailing notion that the pathology underlying cognitive impairment begins decades prior to onset of detectable symptoms; thus, long-term antioxidant intake could be most relevant for cognitive outcomes in later life. We took advantage of multiple, repeated dietary assessments administered over 2 decades in the NHS to examine relations between long-term antioxidant intake and subsequent cognition in approximately 16,000 older women.
Abstract and Introduction
Abstract
The authors examined long-term antioxidant intake in relation to cognitive decline among older women. Beginning in 1980, Nurses' Health Study (NHS) participants completed dietary assessments every 4 years; in 1995–2001, 16,010 participants aged ≥70 years completed initial cognitive assessments, which were repeated 3 times at 2-year intervals. Long-term antioxidant intake was averaged from 1980 through the time of initial cognitive interviews. Multivariable-adjusted linear regression was used to estimate mean differences in rates of cognitive decline across categories of vitamin E, vitamin C, and carotenoid intake; statistical tests were 2-sided. No associations were evident for vitamin E or total carotenoid intake and cognitive decline (e.g., after multivariable adjustment, P-trend = 0.44 and P-trend = 0.51, respectively, for a global composite score averaging all 6 cognitive tests), although higher lycopene intake and lower vitamin C intake were related to slower cognitive decline. In alternative analyses of overall cognitive status at older ages (averaging all 4 cognitive assessments), results for vitamins E and C were generally null, but higher carotenoid intake was related to better cognition. Overall, long-term vitamin E and C intakes were not consistently related to cognition, although greater consumption of carotenoids may have cognitive benefits in older adults.
Introduction
Experimental data indicate that oxidative stress plays an important role in the development of cognitive impairment and Alzheimer's disease, but epidemiologic studies have produced conflicting results on the association between antioxidant vitamins and cognition in older adults. In particular, several large clinical trials of vitamin E, vitamin C, and beta-carotene supplements have shown little effect on cognitive function, with follow-up periods of 3–7 years. However, 1 trial suggested that long-term supplementation with beta-carotene, over approximately 18 years, can confer cognitive benefits, and an additional analysis by our research group indicated that long-term exposure to vitamin E supplements might be associated with cognitive health in the Nurses' Health Study (NHS). These findings are consistent with the prevailing notion that the pathology underlying cognitive impairment begins decades prior to onset of detectable symptoms; thus, long-term antioxidant intake could be most relevant for cognitive outcomes in later life. We took advantage of multiple, repeated dietary assessments administered over 2 decades in the NHS to examine relations between long-term antioxidant intake and subsequent cognition in approximately 16,000 older women.