ACHE and dementia: Results of analysis of covariance with a repeated measures (n = 240) design analyzing the influence of anti-dementia drugs effect (i.e., no anti-dementia drug, acetylcholinesterase inhibitors or memantine), time effect (i.e., time between before and after anti-dementia drugs introduction) and their interaction on the coefficient Cov of stride time (dependent variable) among participants (n = 120)