The effect of non-pharmacological interventions on cognitive function in cancer: an overview of systematic reviews.

Purpose: A significant number of cancer survivors experience cancer-related cognitive impairment (CRCI), which can impact their ability to think, reason, make decisions, and perform daily actions. In recent years, non-pharmacological interventions for CRCI have gained significant attention. These interventions include exercise, cognitive behavioural therapy, cognitive training/remediation, dietary, mind-body, and multi-modal/complex interventions. This umbrella review provides a critical overview to inform guidelines and current practice, identify the most promising interventions, and uncover gaps in the research literature.

Methods: This umbrella review of systematic reviews was pre-registered on Open Science Framework and PROSPERO. Six databases were searched. Systematic reviews (SR) assessing any non-pharmacological interventions to improve cognition in cancer (any type) were included. The overview followed gold-standard guidelines and recommendations. The results were narratively synthesised, and descriptive statistics and effect size ranges were calculated.

Results: Sixty-four (n = 64) SRs were included. Results were synthesised into four non-pharmacological domains. Cognitive training/rehabilitation had the strongest evidence for efficacy. Physical activity/exercise showed promising efficacy; however, the variability of findings was considerable. Mind-body and psychological/behavioural therapy interventions were limited, but there was evidence for short-term effectiveness. Multi-modal/complex interventions showed potential for improving cognition in cancer but were poorly defined.

Conclusions: Overall, non-pharmacological interventions demonstrated efficacy for improving cognition in cancer. There were limited intervention characteristics within domains which were consistently related to efficacy. Three key recommendations are provided for future research: (1) adopt harmonisation and reporting guidelines; (2) develop definitional guidelines of cognitive domains for CRCI research; and (3) assess intervention and participant characteristics associated with positive versus null/negative findings.