Physical activity and cognition: A narrative review of the evidence for older adults

Researchers have long been interested in understanding the potential benefits of physical activity for cognitive performance. Given that advancing age is associated with cognitive decline and is predictive of a heightened risk of clinical cognitive impairment, older adults are a vulnerable population that may particularly benefit from physical activity participation. Objectives: The goal of this narrative review is to consider evidence relative to the beneficial effects of physical activity for cognitive performance, brain structure, and brain function in older adults. Methods: The current state of the literature is presented for studies incorporating behavioral and neuroimaging outcomes. We focus on the highest quality published evidence using the Oxford Centre for Evidence-Based Medicine (2009) evaluation scheme. Thus, we consider meta-analytic reviews followed by experimental, prospective, and cross-sectional empirical evidence. In the absence of meta-analytic evidence, we present a comprehensive review and discuss exemplars of studies to illustrate important points. Results: Findings from these studies have enhanced our understanding of the potential role of physical activity in the enhancement and/or maintenance of cognitive function into advancing age. In sum, prospective evidence provides level 2a evidence and a B+ recommendation that physical activity reduces the risk of cognitive decline and clinical cognitive impairment. Experimental evidence provides level la evidence and an A- recommendation for small-to-moderate benefits for behavioral outcomes. Evidence from neuroimaging studies is less well developed and generally did not merit grade recommendations, with the exception of A- evidence for a positive effect of exercise on hippocampal volume. With respect to brain function, there is level 1b evidence of benefits using fMRI data and level 3b evidence of benefits using ERP data. Conclusions: Further advancement in this area will be reliant on large-scale RCTs of sufficient duration to pursue questions related to the mediating roles of brain structure and function in the observed behavioral benefits of physical activity.