Abstract
Physical activity shows promise as a modifiable risk factor for age-related neurocognitive decline. Although a large body of literature exists on the role of physical activity in reducing age-related declines in cognition and brain morphology and function, there are inconsistencies in the evidence from observational and intervention studies. Both observation and intervention study designs in the area are limited by not adequately addressing or investigating the differential effects of physical activity by the type, frequency, duration or intensity of bouts. Consequently, guidelines for the most appropriate dose of physical activity for promoting healthy brain ageing are not available to the population or clinicians. Therefore, the aim of this thesis was to investigate the effect of physical activity dose on the neurocognitive function of adults over the age of 50.Initially, we found older adults did not accurately self-report the duration of light, moderate or vigorous physical utilising two commonly used questionnaires. Following on from this finding, a greater duration of objectively measured moderate-intensity physical activity was associated with grey matter volumes of the left and right superior frontal gyri. In comparison, neither objectively measured light- or vigorous-intensity physical activity was associated with grey matter volume or cognitive function. Next, we conducted a systematic review with meta-analysis and found exercise interventions improved cognitive function in adults over the age of 50 years, particularly when exercise was of at least moderate-intensity. Building on the findings of the initial studies, we found preliminary evidence in a population of older cancer survivors that an aerobic exercise intervention of high-intensity interval training provides a superior benefit to moderate-intensity continuous training for cognitive function. The findings of this thesis provide additional evidence for the role of physical activity in reducing age-related neurocognitive decline, moreover, they advance the literature by demonstrating the differential effects of physical activity dose. Future research building on these findings will contribute towards a greater understanding of the effect of physical activity on neurocognitive function to provide evidence-based guidelines on the optimal dose for healthy brain ageing.
| Date of Award | 2018 |
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| Original language | English |
| Supervisor | Ben RATTRAY (Supervisor), Kate PUMPA (Supervisor) & Disa Pryor (Supervisor) |