Mapping Associations Between Gait Decline and Fall Risk in Mild Cognitive Impairment

OBJECTIVES Compared to their cognitively healthy counterparts, older adults with mild cognitive impairment (MCI) exhibit higher risk of falls, specifically with injuries. We sought to determine whether fall risk in MCI is associated with decline in higher-level brain gait control. DESIGN Longitudinal study. SETTING Community-dwelling adults from the Gait and Brain Study Cohort. PARTICIPANTS A total of 110 participants, aged 65 years or older, with MCI. MEASUREMENTS Biannual assessments for medical characteristics, cognitive performance, fall incidence, and gait performance for up to 7 years. Seven spatiotemporal gait parameters, including variabilities, were recorded using a 6-meter electronic walkway. Principal components analysis was used to identify independent gait domains related to higher-level (pace and variability domains) and lower-level (rhythm domain) brain control. Associations between gait decline and incident falls were studied with Cox regression models adjusted for baseline covariates. RESULTS Of participants enrolled, 40% experienced at least one fall (28% of them with injuries) over a mean follow-up of 31.6 +/- 23.9 months. From the pace domain, slower gait speed (adjusted hazard ratio [aHR] per 10-cm/s decrease = 4.62; 95% confidence interval [CI] = 1.84-11.61; P = .001) was associated with severe injurious falls requiring emergency room (ER) visit; from the variability domain, stride time variability (aHR per 10% increase during follow-up = 2.17; 95% CI = 1.02-4.63; P = .04) was associated with higher risk of all injurious falls. Rhythm domain was not associated with fall risk. Decline in pace domain was significantly associated with falls with ER visit (aHR = 3.67; 95% CI = 1.46-9.19; P = .005). After adjustments for multiple comparisons, gait speed and pace domain remained significantly associated with falls with ER visits. No statistically significant associations were found between gait domains and overall falls (P >= .06). CONCLUSION Higher risk of injurious falls in older adults with MCI is associated with decline in gait parameters related to higher-level brain control.