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Abstract
Chronic musculoskeletal pain is common in older adults and often leads to lower physical activity. Yet, some older adults with pain remain physically active, thereby seemingly resilient to pain’s negative effect on physical activity. This dissertation tests the central hypothesis that behavioral and neural measures of motivation protect against the detrimental effects of pain on physical activity across three cohorts: Aim 1 in the Cardiovascular Health Study (n = 902, median age = 73, 65% female, 14% Non-White), Aim 2 using longitudinal data from the Health, Aging and Body Composition study (n = 2,209, median age = 73, 51% female, 39% Black), Aim 3 in the Study of Muscle, Mobility, and Aging-Brain (n = 130, median age = 75, 54% female, 8% Non-White).
The main finding of Aim 1 was that approximately 1 in 5 older adults with pain met or exceeded recommended leisure time physical activity (LTPA) levels, indicating this form of pain resilience is not uncommon. In this cross-sectional analysis, higher social network scores and less “difficulty getting going" were associated with higher LTPA, independent of demographics and other health factors. Aim 2 extended these findings longitudinally, showing that perceived energy positively predicted LTPA over the following nine years, and this was independent of pain. These results support my hypothesis that in persons with pain, motivation may positively influence LTPA. Aim 3 deepened this line of inquiry by examining PET-derived measures of striatal [ 11C]DTBZ binding, a neurobiological correlate of motivation, and state of the art objective measures of physical activity. In this cross-sectional analysis higher striatal [ 11C]DTBZ binding showed a trend with higher step count, independent of pain. In secondary analyses, higher striatal [ 11C]DTBZ binding was associated with more moderate-to-vigorous activity, also independent of pain. However, in this sample pain was not significantly associated with physical activity.
Together, these findings reveal that both behavioral and neurobiological markers of motivation are associated with physical activity in older adults, even in the presence of pain, and suggests new targets for interventions to promote healthy and active aging.