Diet and cognitive decline at middle age: the role of antioxidants

To assess the relationship between dietary intake of antioxidants (vitamin C, vitamin E, β-carotene, lutein, flavonoids and lignans) and cognitive decline at middle age, analyses were performed on data from the population based Doetinchem Cohort Study. Habitual diet and cognitive function were assessed twice with a 5-year interval in 2613 persons aged 43-70 year at baseline (1995-2002). Diet was assessed with a validated 178-item semi-quantitative FFQ. Cognitive function was assessed with a neuropsychological test battery, consisting of the 15 Words Learning Test, the Stroop Test, the Word Fluency test, and the Letter Digit Substitution Test. Scores on global cognitive function, memory, processing speed, and cognitive flexibility were calculated. In regression analyses, quintiles of antioxidant intake were associated with change in cognitive domain scores. Results showed that higher lignan intake was linearly associated with less decline in global cognitive function (P= 0.01), memory (P< 0.01) and processing speed (P= 0.04), with about two times less declines in the highest v. the lowest quintile. In the lowest quintile of vitamin E intake, decline in memory was twice as fast as in all higher quintiles (P< 0.01). Global cognitive decline in the highest lutein intake group was greater than in the lowest intake group (P< 0.05). Higher flavonoid intake was associated with greater decline in cognitive flexibility (P for trend = 0.04). Intakes of other antioxidants were not associated with cognitive decline. We conclude that within the range of a habitual dietary intake, higher intake of lignans is associated with less cognitive decline at middle age.