The Association Between Macronutrient Intake and Cognitive Function in Community-Dwelling Elders

Macronutrients as modifiable cognitive protective/risk factors have been examined with inconsistent findings. Few data are available for Mild Cognitive Impairment (MCI) and its subtypes. This thesis examines relationships between cognitive function and macronutrient intake in 813 non-demented, community-dwelling elders from the Sydney Memory and Ageing Study, and investigates age, sex and Apolipoprotein E (APOE) genotype influences. Data was derived from a cross-sectional cohort study in which participants had completed a validated food frequency questionnaire (FFQ). Intakes of energy, total fat and fatty acid subtypes, carbohydrate and its composition, fibre and protein were derived and expressed in grams consumed as a percentage of daily energy intake. Measures of cognitive function were available from a battery of neuropsychological tests encompassing six cognitive domains. A consensus diagnosis of MCI had been made according to internationally accepted MCI criteria (Winblad et al., 2004). Two MCI subtypes were defined - amnestic and non-amnestic MCI. A comprehensive array of potential confounding variables were measured and included in the analyses. The thesis first investigates the association between dietary macronutrient intake and cognitive domain scores. It then examines the association between macronutrient intake and MCI subtypes. In the first study, MUFA intake was found to increase global cognition, fine motor and memory performance, while PUFA intake was positively associated with memory performance in the total cohort. Results with MUFA were also mirrored in the younger-elderly and women groups. In this study, increased energy intake was observed to be associated with increase global cognition scores. In the second study, increased starch intake was associated with reduced odds for MCI in the total cohort. For men, increased SFA, starch and protein intakes reduced the odds for MCI while increased sugar intake was observed to increase the odds for MCI. For the younger-elderly group, increased energy and fibre intake reduced odds for MCI. In this cohort, dietary macronutrient intake was associated with cognitive performance and MCI diagnosis. Age, sex and APOE status also influenced cognitive outcomes. Longitudinal studies are required to determine if diet has a bearing on cognitive outcomes for the participants of the Sydney Memory and Ageing Study