Fig. 2.

This is an example of the effect of dual task walking from one subject (a stride time, usual walking; b stride time dual-task walking). For this subject, the stride time variability increased from 59 to 141 ms (or from 5.6 to 118%). In general, performance of a dual task markedly decreased (p < 0.002) the ability of patients with AD to regulate the stride-to-stride variations in gait timing ( c ). The standard deviation of the stride time (the gait cycle duration) increased by 52% when subjects were asked to walk and talk at the same time. This increase was associated with impaired executive function (see text). Error bars reflect the standard error of the mean. Mean was obtained from all 28 subjects (adapted from Sheridan et al. [12]).