Association of adherence to the Australian Dietary Guidelines with cognitive performance and cognitive decline in the Sydney Memory and Ageing Study: a longitudinal analysis

This study investigated associations of adherence to the Australian Dietary Guidelines (ADG) with cognitive performance and cognitive decline over 6 years. We used longitudinal data from the Sydney Memory and Aging Study comprising 1037 community-dwelling non-demented participants aged 70–90 years. Dietary intake was assessed at baseline using the Dietary Questionnaire for Epidemiological Studies Version 2. Adherence to the ADG was scored using the Dietary Guideline Index 2013 (DGI-2013). Cognition was assessed using neuropsychological tests in six cognitive domains and global cognition at baseline and 2, 4 and 6 years later. Linear mixed models analysed the association between adherence to the ADG and cognitive function and cognitive decline over 6 years. Results indicated that overall adherence to the ADG was suboptimal (DGI-2013 mean score 43⋅8 with a standard deviation of 10⋅1; median score 44, range 12–73 with an interquartile range of 7). The percent of participants attaining recommended serves for the five food groups were 30⋅2 % for fruits, 11⋅2 % for vegetables, 54⋅6 % for cereals, 28⋅9 % for meat and alternatives and 2⋅1 % for dairy consumption. Adherence to the ADG was not associated with overall global cognition over 6 years (β = 0⋅000; 95 % CI: −0⋅007, 0⋅007; P = 0⋅95). Neither were DGI-2013 scores associated with change in global cognitive performance over 6 years (β = 0⋅002; 95 % CI: −0⋅002, 0⋅005; P = 0⋅41) nor in any individual cognitive domains. In conclusion, adherence to the ADG was not associated with cognitive health over time in this longitudinal analysis of older Australians. Future research is needed to provide evidence to support specific dietary guidelines for neurocognitive health among Australian older adults.