Abstract
Cognitive decline, especially for those higher-order functions that allow us to do things like focus our attention, solve problems, hold information in mind, and inhibit unwanted actions, is a normal part of ageing. However, for individuals, cognitive decline represents the possibility of losing their usual competence and independence. For governments and our wider society, the prospective burden of cognitive decline associated with an ageing population represents a significant future cost for health and social services. Thus, researchers have sought accessible interventions that might help to slow age-related cognitive decline. Some of that work has pointed to activity engagement (including social, cognitive, and physical activity) as an important factor. Through three studies and a review chapter, this thesis investigates the links between higher-order cognitive functioning and two activity types: 1) physical activity and 2) volunteering in the community, which often encompasses a combination of social, cognitive, and physical activity. Each chapter has been prepared as its own journal article, and readers should refer to the published versions of each article rather than this thesis. Chapter 2, which is titled "Investigating links between habitual physical activity, cerebrovascular function, and cognitive control in healthy older adults" and published in Neuropsychologia, addresses the need to better understand the mechanisms through which physical activity might benefit cognition by investigating the role of cerebrovascular functioning. Building on the evidence that physical activity is positively linked to cognitive functioning, Chapter 3 (titled "Physical activity prevalence and correlates among New Zealand older adults" and published in the Journal of Aging and Physical Activity) examines current physical activity levels among older adults in New Zealand and considers information that might aid the development of population-level initiatives aimed at promoting physical activity in that age group. Chapter 4 (titled "Volunteering in the community: Potential benefits for cognitive aging" and published in the Journals of Gerontology, Series B: Psychological Sciences and Social Sciences) comprises a review of the evidence to date relating to the potential benefits of volunteering for cognitive functioning in older adulthood. Chapter 5 (titled "Volunteering in the community is associated with activity engagement and better cognitive functioning") reports a study that investigated links between volunteering and cognitive functioning, and whether increased engagement in social, cognitive, and physical activity could be mechanisms through which volunteering might benefit cognition. Together, this work fills some important gaps in understanding the links between activity engagement and cognitive functioning in older adults, and provides information that can be used to guide future research toward accessible ways to promote healthy cognitive ageing.