WESTERN DIET MAY ATTENUATE THE BENEFICIAL EFFECT OF MODERATE ADHERENCE OF MEDITERRANEAN DIET ON COGNITIVE DECLINE

The Mediterranean diet (MedDiet) has been associated with slower cognitive decline whereas the Western diet is reported to affect cognition adversely. Currently, there is limited knowledge of the impact on cognition of consuming both; i.e., whether eating unhealthy foods that are part of the Western diet may offset the potential benefits of consuming the healthy foods of a MedDiet. In this study, we investigated whether consumption of the Western diet modified the association of the MedDiet on cognitive change in the biracial population of the Chicago Health and Aging Project (CHAP). Analyses included 4,985 CHAP participants (63% African American, mean age=75±6.0 years, mean education=12.6±3.6 years) who completed a food frequency questionnaire and at least two cognitive assessments (a composite of 4 tests) every 3 years over an average follow-up of 6.3 years (±2.8). We computed a Western diet score based on factor analyses of reported intakes among CHAP participants of 144 food items; higher scores represent high consumption of red meat, refined grains, snacks, and sweets. Computed scores of adherence to the MedDiet score were analyzed linearly and in tertiles. For all analyses, we used mixed models with cognitive scores regressed on diet scores and model covariates for age, sex, education, race, participation in cognitive activities, physical activity, and total calorie intake. To test for effect modification, we added multiplicative terms of the diet scores: MedDiet (tertile 2, tertile 3 vs. tertile 1) and Western diet (high vs. low score). Overall MedDiet score was linearly associated with slower cognitive decline (β=0.0015, p=0.001). The association for moderate intake of the MedDiet with slower cognitive decline was modified towards null for those consuming high Western diet (p for T2 interaction=0.01) and not in those with a low Western diet. No modification of effect by the Western diet was observed for the highest MedDiet score (p for T3 interaction=0.13). Consumption of Western diet foods may attenuate the beneficial effect of moderate adherence to a Mediterranean diet on cognition. Further study is required to understand the combined effect of healthy and unhealthy food choices or associated factors on cognition.