Abstract
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.
Highlights
Increasing numbers of people are living with mild cognitive impairment (MCI) or dementia worldwide[1,2,3] against the background of increased longevity
The cohort of 1037 participants (55⋅2 % female, n 572) had an average age of 78⋅8 years, a mean education level of 11⋅6 years (11⋅0 years for women; 12⋅3 years for men) and a mean BMI of 25⋅7 kg/m2 (25⋅3 kg/m2 for women; 26⋅1 kg/m2 for men) at baseline; 15⋅8 % were from non-English-speaking background (NESB)
Dietary data were missing for 6⋅9 % (n 63 incomplete and n 9 misreported); global cognition data were missing for 0⋅5 % (n 5) at baseline and 38⋅9 % (n 403) at wave 4 (Supplementary Table S3)
Summary
Increasing numbers of people are living with mild cognitive impairment (MCI) or dementia worldwide[1,2,3] against the background of increased longevity. Positive effects on cognitive health have been reported, in association with higher adherence to healthy dietary patterns such as the Mediterranean, Dietary Approaches to Stop Hypertension (DASH) and Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diets as well as prudent healthy diets generated through data-driven methods. Among these diets, the Mediterranean diet is the most investigated by numerous studies including the US study. The DASH diet, less studied than the Mediterranean diet[17], was positively associated with better cognitive function among older adults by studies such as the MAP[13], the Cache County Study[18] and the Nurse’s Health Study[19]. The MIND diet was investigated by the MAP[13,20] and the Nurse’s Health Study[21] and has been suggested as having the strongest association with less cognitive decline and dementia risk, when compared to Mediterranean and DASH diets[17], but more evidence on the MIND diet is required
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