The Impact of a Physical Activity Intervention on Cognitive and Mental Health Outcomes in Cancer Survivors.

Physical activity (PA) is a safe, effective non-pharmacological method for reducing many adverse symptoms among cancer survivors. However, evidence supporting the benefits of digital PA interventions on cognitive function, anxiety, and depression among survivors is inconsistent, with very few examining the fear of cancer recurrence (FCR). This trial with a cohort study aimed to examine the impact of a one-year digital PA intervention on changes in cognitive and mental health outcomes among cancer survivors. 415 participants were randomized 2:1 to an interactive PA website or flexibility control website. Anxiety, depression, FCR, and perceived cognitive function measured at baseline and at three-, six-, and 12-month follow-ups were analyzed using linear mixed models adjusted for age. Two post-hoc analyses were performed: (1) stratified by compliance with website protocol and (2) excluding participants at baseline with low anxiety, depression, or FCR, or high cognitive functioning. 94% of participants included in this analysis were women (n = 368) with a mean age of 62 years (SD = 8.5). In intent-to-treat models, the intervention was not effective in improving depression, anxiety, cognitive function, or FCR; however, among participants with high baseline FCR, engaging with the PA website intervention led to a significant reduction in FCR throughout the trial duration (compliant: 19.2 [16.8-21.6] at month 12 compared to 23.8 [21.3-26.2] at baseline). Overall, the intervention showed no meaningful effects on depression, anxiety, or perceived cognitive function. Post-hoc findings suggested reduced FCR among compliant survivors with elevated baseline FCR, warranting prospective validation. This trial was registered on ClinicalTrials.gov (NCT05356988).