1 PERFORM Centre, Concordia University, Montréal, Quebec, Canada.
2 Centre d'excellence sur le vieillissement de Québec, Centre de recherche du CHU de Québec, Canada.
3 Centre de recherche sur les soins et les services de première ligne de l'Université Laval, Canada.
4 Rotman Research Institute, Baycrest Health Sciences, Toronto, Ontario, Canada.
5 Department of Nutritional Sciences, University of Toronto, Ontario, Canada.
6 Departments of Psychiatry and Psychology, University of Toronto, Ontario, Canada.
7 Département de nutrition, Université de Montréal, Quebec, Canada.
8 Research Center, Montreal Heart Institute, Quebec, Canada.
9 Centre de recherche du Centre hospitalier de l'Université de Montréal, Quebec, Canada.
10 Département de médecine, Université de Montréal, Quebec, Canada.
11 Centre de recherche, Institut universitaire de gériatrie de Montréal, CIUSSS du Centre-sud-de-l'Île-de-Montréal, Quebec, Canada.
12 School of Dietetics and Human Nutrition, McGill University, Montréal, Quebec, Canada.
13 Division of Geriatric Medicine, McGill University, Montréal, Quebec, Canada.
14 Department of Psychology, Ryerson University, Toronto, Ontario, Canada.

Objective: This study examined the effect of dietary patterns and engagement in cognitive stimulating lifestyle behaviours on trajectory of global cognition, executive function (EF), and verbal episodic memory (VEM).

Method: Western and prudent dietary patterns were empirically derived using food frequency questionnaire responses from 350 community-dwelling older adults (mean age: 73.7 years) participating in the Québec Longitudinal Study on Nutrition and Successful Aging. Cognitive stimulating lifestyle (CSL) was represented by a binary composite indicator based on education, occupational complexity, and social engagement. Global cognition, EF, and VEM were assessed prospectively.

Results: Primary effect models revealed an association between higher Western dietary pattern score and greater rate of decline in global cognition and EF. Higher Western dietary pattern adherence also associated with poorer baseline VEM.. Primary effect models also revealed that CSL independently associated with baseline global cognition and EF. Effect modification models suggested an interactive effect between Western dietary pattern and CLS on global cognition only. No associations were found for prudent dietary pattern score.

Discussion: Contributing to existing research supporting the negative impact of consuming an unhealthy diet on cognitive function, the current study suggests increased vulnerability among older adults who do not engage in a cognitive stimulating lifestyle. These findings can inform the development of lifestyle intervention programs that target brain health in later adulthood.