Gait speed or gait variability, which one to use as a marker of risk to develop Alzheimer disease? A pilot study

Previous literature demonstrates the interest of gait analysis to predict cognitive decline in old people. This pilot study aims to determine if gait speed or gait variability is a marker able to early identify, among mild cognitive impairment (MCI) subjects, those at risk to develop Alzheimer's disease (AD) in the future. 13 MCI subjects were included in 2007. Their gait parameters (walking speed, stride length and gait frequency, regularity and symmetry) were measured in 2007 and 2008 in simple task (ST) and in dual task (DT) using a triaxial accelerometer (Locometrix(A (R))). Among the 13 MCI subjects included in 2007, 10 were assessed in 2008. So, 23 (13 in 2007 + 10 in 2008) gait tests were collected. In 2011, MCI people were considered as "MCI+" when they developed AD (between baseline and 2011) and as "MCI-aEuroe if they did not. Among the 23 gait tests, 15 were from MCI+ (9 gait tests in 2007 and 6 in 2008) and 8 from MCI- (4 gait tests in 2007 and 4 gait tests in 2008). Mann-Whitney non-parametric U test was used to compare gait parameters of MCI+ and MCI-. Gait speed, symmetry and regularity were lower in MCI+ than in MCI-. Despite the small sample size, the results presented in this original pilot study are in line as the infrequent previous literature related to this topic. The authors discuss lacks and strengths of this work. These results suggest that both gait speed and gait variability could be markers to early identify MCI at risk to develop AD.