Background: Older cancer survivors are at risk for cognitive decline. Physical activity can improve cognition, and better cognitive function may facilitate greater physical activity.
Purpose: We examined the potential bidirectional relationship between cognitive function and physical activity in older breast cancer survivors and controls.
Methods: The sample included women with newly diagnosed, nonmetastatic breast cancer (n = 395) and women without cancer (n = 374) ages 60-98. Participants were recruited as part of a larger multisite study, assessed prior to systemic therapy, and followed yearly for 36 months. Attention, processing speed, and executive function was measured using six neuropsychological tests, self-reported cognitive function using the Perceived Cognitive Impairments subscale of the Functional Assessment of Cancer Therapy-Cognitive Function , and physical activity using the International Physical Activity Questionnaire-Short Form. Separate random intercepts cross-lagged panel models were used to examine the between- and within-person effects for survivors and controls, controlling for age, education, and study site.
Results: Survivors reported significantly less physical activity than controls at baseline (1,284.92 vs. 2,085.98 MET min/week, p < .05). When survivors reported higher activity, they simultaneously had better objective cognition at 12 months (β = 0.24, p = .04) and reported better perceived cognition at 12 and 24 months (β = 0.25, p = .03), but this relationship was not seen in controls. Cognition did not predict subsequent physical activity or vice versa in either group.
Conclusions: Cognition and physical activity are cross-sectionally associated in survivors, but the expected prospective relationships were not found.
Keywords: Breast cancer; Cognition; Executive function; Older survivors; Physical activity.
Physical activity may improve cognitive function for older cancer survivors; however, cognitive function may also affect the ability to organize oneself to be physically active. We examined this potential bidirectional relationship in a sample of 395 women with newly diagnosed, nonmetastatic breast cancer, and 374 noncancer controls. These women completed cognitive tests and surveys yearly for 36 months. Surveys included their subjective cognitive function and physical activity. We examined the relationships between cognitive function (both objective and subjective) and physical activity over time (baseline, 12, 24, and 36 months). We found that when cancer survivors reported higher physical activity, they had better objective cognitive function at 12 months, and they reported better subjective cognitive function at 12 and 24 months. However, physical activity did not predict cognitive function at later time points, and cognitive function did not predict physical activity at later time points. In controls, better subjective cognitive function was related to higher physical activity overall, but there were not relationships over time or at specific time points. This was an observational study; therefore, future research should consider the potential impact of cognitive function when older cancer survivors are attempting to increase their physical activity.
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