Comparing executive function, evoked hemodynamic response, and gait as predictors of variations in mobility for older adults

ABSTRACT

Objective: Falls represent a major concern for older adults and may serve as clinically salient index events for those presenting in the prodromal stages of mild cognitive impairment. Declines in executive function performance and in gait consistency have shown promise in predicting fall risk; however, associated neurophysiological underpinnings have received less attention. In this study, we used a multimodal approach to assess fall risk in a group of older adults with and without a previous fall history.

Method: Processing speed, inductive reasoning, verbal fluency, crystallized ability, episodic memory, and executive functioning were assessed using standardized neuropsychological tests. Cognitive interference was assessed using the Multi-Source Interference Task. Spatiotemporal gait parameters were assessed with and without cognitive load using a 6.4-m instrumented walkway. Hemodynamic responses were measured using functional near-infrared spectroscopy.

Results: Whereas no group differences were observed in cognitive behavioral performance, during a cognitive interference task fallers displayed more oxygenated hemoglobin across the prefrontal cortex than nonfallers, suggesting that engaging in the cognitive task was more effortful for them overall, therefore eliciting greater cortical activation. Between-group differences in spatial as well as temporal gait parameters were also observed.

Conclusions: These results are in keeping with assertions that diminished executive control is related to fall risk. Notably, the group differences observed in prefrontal cortical activation and in gait parameters may ultimately precede those observed in cognitive behavioral performance, with implications for measurement sensitivity and early identification.

KEYWORDS:

• Aging
• fall risk
• functional near-infrared spectroscopy (fNIRS)
• multimodal assessment
• variability

Acknowledgements

Further information about the study may be obtained by contacting S. MacDonald at [email protected]

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. Although the p-value associated with the between-group differences in accuracy for the control condition approached significance, and the corresponding effect size was large (d = 0.83), these values were likely driven by restriction of range and heterogeneity in the nonfaller group. Specifically, most nonfallers and fallers alike performed at ceiling for the control condition; however, 3 nonfallers performed slightly lower (85, 90, and 92% accuracy), which resulted in the larger standard deviation for this group than for the fallers (4.64 vs. 1.04).

Additional information

Funding

This work was supported by grants from the Canadian Institutes of Health Research (Canada Graduate Scholarship, to D. H.); the Natural Sciences and Engineering Research Council of Canada [grant number 418676-2012] to S. M. and M. G-B.; and the National Institutes of Health/National Institute on Aging [grant number R21AG045575] to R. S. and S. M.