Everyday Stepping Quantity and Quality Among Older Adult Fallers With and Without Mild Cognitive Impairment: Initial Evidence for New Motor Markers of Cognitive Deficits?

Background: Recent work demonstrated that the gait of people with mild cognitive impairment (MCI) differs from that of age-matched controls and, in general, that walking ability, as measured in the clinic, does not necessarily reflect actual, daily performance. We evaluated if the quantity and quality of everyday walking (ie, community ambulation) differs in older adults with MCI, compared to age-matched controls. Methods: Inclusion criteria included: age 65-90 years, able to walk at least 5 minutes unassisted, and >= 2 falls in the past 6 months. Subjects with MCI were included if they scored 0.5 on the Clinical Dementia Rating Scale. To assess stepping quantity and quality, subjects wore a tri-axial accelerometer on the lower-back for 7 days. Results: Age and gender were similar (p > .10) in MCI (n = 36, 77.8 +/- 6.4 years; 27.8% men) and controls (n = 100, 76.0 +/- 6.2 years; 22.0% men). As expected, Montreal Cognitive Assessment scores were lower (p < .001) in MCI (21.31 +/- 4.05), compared to controls (25.81 +/- 2.64). Walking time was lower (p = .016) in MCI (0.74 +/- 0.48 hours/d), compared to controls (1.05 +/- 0.66 hours/d). Within-bout walking (eg, stride regularity) was less consistent (p = .024) in MCI (0.51 +/- 0.14), compared to controls (0.58 +/- 0.14). Changes in stride regularity across bouts were lower (p < .001) in MCI (0.13 +/- 0.04), compared to controls (0.17 +/- 0.01). Conclusions: Older adults with MCI walk less and with a more variable within-bout and less variable across-bout walking pattern, as compared to cognitively-intact subjects matched with respect to age and gender. These findings extend previous clinical work and suggest that MCI affects both the quantity and quality of community ambulation.