An association of cognitive function with mobile metrics of community walking in older cancer survivors: A pilot study.

Introduction: Older cancer survivors have an elevated risk for mobility dysfunction compared to their cancer-free peers. Despite the established link between cognitive function and community walking in older cancer-free adults, little is known about this relationship in older cancer survivors. This pilot study aimed to evaluate the association of performance-based and self-reported cognitive function with mobile metrics of community walking collected by a wearable Fitbit device.

Materials and methods: This study enrolled older cancer survivors (mean age 73 years old, range 65-83; 98 % White; 50 % female) within five years of completing primary treatment. Cognitive function, specifically executive function and processing speed was collected with the digit symbol substitution test (DSST) and self-reported cognition was evaluated by the Patient Reported Outcomes Measurement Information System- Cognitive (PROMIS-Cog). Continuous walking data from Fitbit wearable devices were collected passively over four weeks. To examine associations between DSST and PROMIS-Cog with mobile measures of walking, we conducted bivariate correlation and multivariable linear regression analyses adjusting for age, education, and number of comorbidities.

Results: In bivariate analyses, higher DSST scores were correlated with higher step count and peak cadence and lower fragmentation of walking in daily life (r = 0.48-0.51, p < 0.01). Higher PROMIS-Cog scores were correlated with higher peak cadence (r = 0.32, p < 0.05), trended towards correlation with step count (r = 0.30, p = 0.06), and were not correlated with fragmentation of walking (r = -0.24, p = 0.13). In multivariable models adjusting for age, presence of graduate level education, and number of comorbidities, higher DSST scores were independently associated with higher peak cadence, step count, and demonstrated a trend towards lower fragmentation of walking in daily life, but PROMIS-Cog was not independently associated with any mobility metrics. Similar results for association of DSST with walking when models included adjustment for PROMIS-depression scale, receipt of chemotherapy treatment, or when education was defined by presence of a bachelor's degree.

Discussion: This study suggests an association between cognitive functions of executive function and processing speed with mobile metrics of community walking in older cancer survivors. Understanding how cognitive function affects walking may help identify new rehabilitation targets for older cancer survivors.