A prospective examination of change in executive function and physical activity in older breast cancer survivors

Abstract

Only one third of older breast cancer survivors (BCS) meet national physical activity (PA) guidelines. Theories of self-regulation and research with older adults suggest that executive function (EF) plays an important role in PA, yet the impact of lower EF on older survivors’ PA is unknown. My project addressed this gap using secondary data from the Thinking and Living with Cancer (TLC) cohort study, which examined cognitive function among older BCS pre-treatment, followed every 12 months, and contemporaneously assessed matched controls. My first aim was to test two hypotheses regarding EF change and PA and determine if these relationships differ between BCS and controls. My hypotheses were: 1) EF decline from baseline to 12 months will predict lower PA at 24 months, and 2) lower PA at 12 months will predict EF decline from 12 to 24 months. My second aim was to explore whether the effects of EF change on PA in BCS differed based on risk factors for accelerated cognitive decline (i.e., older age, more advanced cancer stage, comorbidity, and APOE ε4 genotype). The TLC study measured EF with neuropsychological tests and PA with the International Physical Activity Questionnaire-Short Form. For aims 1 and 2, I used multiple regression with multiple imputation. Primary results showed no significant effect of EF change from baseline to 12 months on PA at 24 months (β=-0.01, p=0.88) and no significant group (BCS vs. controls) by EF interaction (β=-0.05, p=0.33). Separate models in BCS and controls showed similar findings. In the entire sample, PA at 12 months significantly predicted EF change from 12 to 24 months (β=0.17, p=0.01), but there was no significant group by PA interaction (β=-0.06, p=0.54). Separate analyses by group found a significant effect of PA for controls (β=0.07, p=0.02), but not for BCS (β=0.05, p=0.27). Regarding the second aim, there were no significant interactions between EF change and the proposed risk factors on PA. Findings were largely inconsistent with theory and prior research. Continued research in this area will inform future exercise interventions to improve physical and cognitive health for the growing population of older cancer survivors.