Associate Professor, University of Toronto
Chair: Dr. Wendy E. Ward
Diet and exercise are known to have long-term positive influences on reducing the risk of neurological diseases. This symposium will highlight two key areas of interest: understanding how diet and the brain itself regulates its polyunsaturated fatty acid composition; and how physical exercise facilitates functional reorganization of neural network processing to accommodate the infrastructure of an aging neural system. Implications of current findings for developing nutritional and exercise recommendations that promote and support brain health and cognition will also be discussed. Given the aging population as well as the overall importance of diet and exercise in everyday life, it is timely to bring together these complimentary aspects that support brain health and overall healthy active living.
The impact of physical exercise on brain complexity in aging
Jennifer J. Heisz, Ph.D.
Regular physical exercise promotes cognition in aging, yet the underlying mechanisms remain unknown. One hypothesis suggests that physical activity in older adults may preserve youth-like neural structure and function. However, these studies have been unable to convincingly link neural preservation in advancing age with the cognitive benefits of physical activity. The present study reveals a novel mechanism whereby physical exercise does not preserve youthful-like brain function but rather facilitates functional reorganization of neural network processing to accommodate the infrastructure of an aging neural system. The results suggest that physical exercise acts as a catalyst for change by increasing the fundamental components for neuroplasticity. For older adults, the reorganization of brain processing may be difficult to achieve without the promotion of neuroplasticity through external factors such as physical activity. Consequently, older adults who lack the necessary supplements for plasticity will continue to process information as they did prior to age-related neural degeneration, even if that way has become suboptimal. This research is an important first step in elucidating the mechanisms through which physical exercise changes the brain to promote cognition. Future research may reveal possible synergistic effects of combining exercise and nutrition regimens in the promotion of brain dynamics in aging. The ultimate goal of this work is to inform prescriptions for exercise to keep the growing aging population both physically and mentally healthier for longer.
What the rate of fatty acid entry into the brain tells us about nutritional requirements
Dr. Richard Bazinet
The brain is especially enriched with the polyunsaturated fatty acids (PUFA) docosahexaenoic acid (DHA) and arachidonic acid, while being virtually devoid of other PUFA such as eicosapentaenoic acid (EPA). It has been suggested that the plasma supply to the brain regulates brain PUFA levels and replaces PUFA consumed in the brain. Candidate plasma pools that supply the brain with PUFA include the plasma unesterified pool, PUFA esterified to lysophosphatidylcholine or the uptake of PUFA-containing lipoproteins via lipoprotein receptors into endothelial cells of the blood brain barrier. This paper will first present recent basic studies that have examined the role of lipoprotein receptors and the kinetics of candidate plasma pools which supply the brain. Upon presenting evidence that the plasma unesterified pool is a major source of brain PUFA, especially for DHA, I will describe how rapid metabolism also maintains very low levels of certain PUFA, such as EPA. Because fatty acid uptake into the brain can be imaged in humans, we can now, for the first time, estimate brain PUFA, including DHA, requirements. The paper will conclude with a discussion on how diet can maintain brain DHA levels and function with a focus on marine and plant based omega-3 fatty acids
Associations between cardiovascular disease risk factors and executive function in the NutCog Study
Guylaine Ferland (Abstract Presentation)
Introduction: There is growing evidence for a role of cardiovascular disease risk factors (CVDRF) in the development of cognitive deficits during aging. Observational studies have shown that elevated plasma homocysteine (Hcy) and indicators of lipid metabolism are potentially modifiable risk factors for cognitive aging. Executive functions (EF) which refer to the brain components involved in the planning and control of complex tasks is one cognitive domain affected by aging. Objective: Explore the associations between circulating CVDRF markers and EF in community-dwelling elderly individuals. Methods: Plasma Hcy and serum indicators of lipid metabolism and EF were assessed in 159 men and 193 women (mean age = 77.3 y, SD=3.9) from the NutCog Study, a sub-study of the Quebec Longitudinal Study on Nutrition and Aging. EF were assessed using components of the Rey Complex-Figure copying, the Stroop test, the Browne Peterson procedure, and the (WAIS-III) Digit Symbol-Coding subtest. Associations between circulating markers and EF were assessed at recruitment and two years later using regression models. Results: Increased plasma levels of Hcy (p=0.0005) and serum triglycerides (p=0.0263) were associated with lower EF at both time points whilst higher levels of serum high density of lipoproteins (HDL) were marginally associated (p = 0.0617) with better performances. Conclusion: These preliminary results add to the hypothesis of a link between cardiovascular health and cognition in aging. The fact that CVDRF are modifiable through diet and exercise suggest that EF could be ameliorated in the elderly through lifestyle changes. The study was funded by the Réseau Québécois de recherche sur le vieillissement.
Professor and Canada Research Chair in Bone and Muscle Development, Brock University
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