Onset of cognitive impairment, diet quality and adherence to dietary guidelines over 12 years: The Personality and Total Health Cohort Study

Abstract

Around 55 million people worldwide live with dementia, and more are expected due to population ageing. We aimed to investigate associations between healthy diet and mild cognitive impairment and dementia in 1753 older adults aged 60-64 from the PATH (Personality and Total Health Through Life Cohort) study. Healthy diet was defined by the Mediterranean-DASH diet Intervention for Neurological Delay (MIND) and two dietary guideline quality scores (Dietary Guideline Index (DGI) and Index Diet Quality (IDQ)), which were calculated from baseline FFQ. Higher dietary scores indicated higher diet quality. Incidence of Alzheimer's disease/vascular dementia (National Institute of Neurological Disorders criteria) and mild cognitive impairment (Winbald criteria) was assessed after 12 years of follow-up using validated questionnaires with nominated proxies. Logistic regression explored associations between dietary scores and cognitive function, adjusting for demographics, lifestyle factors and medical preconditions. Adjusted logistic regression comparing the per unit linear increase in diet scores showed MIND (OR = 0·82, 95 % CI = 0·68, 0·99), but not DGI (0·99 (0·97, 1·00)) or IDQ (1·12 (0·95, 1·32)), was significantly associated with lower odds of developing cognitive impairment. In conclusion, a healthier neuroprotective dietary pattern is associated with better cognitive function over time, whereas dietary patterns generated from general dietary guidelines did not show a significant association. Further research and well-designed clinical studies are needed to determine the effects of the MIND diet on cognitive impairment in older adults without a family history of dementia.