Who uses it and who loses it? Personality, activity engagement and cognitive health in old age
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Identifying strategies to promote cognitive health in older age is a key research priority as older adults continue to make up a growing proportion of the global population. The ‘use it or lose it’ theory proposes that leading a more active, engaged lifestyle can be cognitively protective. Cross-sectional studies provide support for this, with evidence suggesting that older adults who are mentally, physically, socially and creatively active in their everyday lives may also have higher levels of cognitive ability and experience lower levels of cognitive decline. Intervention studies can provide further insight, going beyond cross-sectional associations to explore causality by testing the effect of increased engagement in an experimental paradigm. It is essential that such interventions consider the importance of individual differences; in particular, evidence suggests that individual differences in personality might predict activity engagement, and in turn cognitive health. It is therefore possible that individual differences in personality might influence engagement level within an intervention, and in turn the degree of benefit received. The PhD research reported in the present thesis examined these possibilities using data collected from a large-scale, activity-based intervention study known as The Intervention Factory. This study tested the cognitive benefits of activity engagement in a more real-world environment by using existing, community based classes and groups. A sample of 336 adults aged 65 and over without any diagnosed cognitive impairments were recruited and completed baseline assessments. Cross-sectional data at baseline were used to examine whether lifestyle variables such as activity engagement mediated any associations between Big Five personality traits and cognitive ability across several domains. Higher Openness to Experience and lower Neuroticism and Extraversion predicted higher levels of cognitive performance, but there was no evidence to suggest these associations were mediated by activity engagement. The PhD research then examined whether personality might influence activity engagement and cognitive change within the context of an intervention. A systematic review of the literature found ten studies that had previously explored this question; there was some evidence that higher Openness to Experience was linked to greater cognitive gains when studies used novel intervention methods. This theory was then tested within the context of The Intervention Factory specifically. Participants were pseudo-randomly allocated to one of five activity groups (computer classes, dance/exercise/sport classes, social/bingo groups, language classes or handicraft/woodcraft classes) or a no-contact control group and attended their activity for around ten weeks. None of the activity groups showed evidence of significantly greater cognitive improvements compared to the control group over the course of the intervention. There was also no reliable evidence that individual personality traits predicted adherence or moderated intervention-related cognitive change. While these results did not support the efficacy of real-world activities to promote cognitive health, several challenges were identified that will inform and encourage future research in this area. These challenges included issues arising from non-random group allocation, difficulty recruiting an effective control group and variability in intervention delivery when translated to a more real-world setting. Addressing these challenges in future studies will provide further opportunities to explore the potential cognitive benefits of real world activities, and whether any benefits vary at the individual level.