Background: Although the close relationship between mobility and cognitive declines is well-known, literature has very little questioned whether improvement in walking speed over time could be associated with improvements in cognitive functions. The objective of this study was to examine the associations between a clinically meaningful improvement in walking speed and global and specific cognitive changes in older adults.
Design: Prospective cohort study.
Setting: Multidomain Alzheimer Preventive Trial (MAPT) study.
Participants: Three-hundred participants from the control group of the MAPT study (mean age 74.8 ± 4.2; 57% women).
Measurements: The 4-m usual walking speed, global cognition, memory, executive functions, and processing speed measures were collected at baseline, and at 6, 12, 24 and 36 months. Participants were categorized into three groups according to their walking speed change over the three-year study: 1/ Non-Improvers (participants not presenting an increase ≥0.05m/sec on walking speed; n=138); 2/ Improvers (increase ≥0.05m/sec; n=40); Cyclic (≥0.05m/sec improvement at some time points without maintaining it through the whole period; n=122).
Results: Adjusted mixed-effect linear regressions revealed that walking speed improvers did not significantly differ from participants who never or temporarily improved their walking speed on all of global and specific cognitive functions over three years. Nevertheless, a sensitivity analysis (excluding participants with a non-clinical walking speed improvement) indicated specific cognitive trajectories per group associated with better episodic memory scores for Improvers compared to non-improvers (β=2.41, 95% CI=.12 - 4.71; p=.039).
Conclusion: This study found that the overtime trajectories of cognitive functions did not differ as a function of clinically meaningful walking speed changes in older adults. Nevertheless, secondary analyses provided new insights on the relationship between walking speed and specific cognitive functions. The novelty of this approach (switching from declines to improvements) should be considered in future large-scale, observational longitudinal studies.
Trial registration: ClinicalTrials.gov NCT01513252.
Keywords: Walking speed; clinically relevant; executive functions; longitudinal study; memory.