UBC Theses and Dissertations
Light, moderate, and vigorous physical activity and 9-year changes in cognitive performance : test of age moderation Stuart, Nicole
Physical activity (PA) has been linked to better cognitive performance, although less is known regarding the potential benefits of different intensities of PA on long-term cognition and if these benefits differ by age. Therefore, the present study examined age moderation in the associations of light, moderate, and vigorous intensity self-reported leisure-time PA with 9-year change in cognitive performance. On an exploratory basis, we examined inflammatory biomarkers interleukin (IL)-6, IL-8, and C reactive protein as mediators, and tested age as a moderator of this mediation. Data came from 2311 adults (aged 35-85 at baseline, 57% female) from the Midlife in the United States Study. At baseline and approximately 9 years later, physical activity was measured via questionnaire, and cognitive performance was assessed via telephone, tapping into episodic memory and executive function. In regression models, PA intensities were evaluated as predictors of later cognitive performance and age was examined as a moderator of these links. Analyses controlled for baseline cognition, depressive symptoms, and sociodemographics. When examined separately, moderate and vigorous (but not light) intensity PA each predicted better 9-year episodic memory, but only the association for moderate PA remained when controlling for all PA intensities. This association was not evident for executive functioning. Age did not moderate any these associations. In exploratory analyses (n = 906 participants who had provided blood samples), none of the inflammatory markers mediated the relationship between physical activity and later memory, and age did not moderate this relationship. These findings suggest that moderate leisure-time PA may be protective for forestalling age-related changes in episodic memory across the adult lifespan. Given that inflammatory markers did not mediate this relationship, future work should focus on delineating the underlying mechanisms.
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