Gait control: a specific subdomain of executive function?

Seventy-eight healthy older adults (mean age 69.9 ± 0.9 years, 59% women) were divided into 3 groups according to stride time variability (STV) tertiles while steady state walking. Coefficient of variation of stride time was used as a marker of STV. Scores on cognitive tests evaluating information updating and monitoring (Digit Span test), mental shifting (Trail Making Test part A and part B) and cognitive inhibition (Stroop Color Word test) were used as measures of ESD.The full adjusted and the stepwise backward logistic regression models showed that the highest tertile (i.e., the worst performance) of STV was only associated with lower Digit Span performance (Odds ratio = 0.78 with P = 0.020 and Odds ratio = 0.81 with P = 0.019).Information updating and monitoring are associated with STV in the sample of studied participants, suggesting that walking may be a complex motor task depending specifically of this subdomain of executive functions.Walking is considered as an automatic motor activity mainly controled by subcortical and spinal regions [1]. Stride-to-stride variability of stride time (STV) is a measure of the reliability of lower limb movements and is a dependable marker of the rhythmic stepping mechanism [2,3]. A low STV (i.e.; under 5%) reflects an efficient gait control [3]. The past decade highlighted that cognitive functions, and in particular executive functions (EF), are associated with STV and play an important role in gait control even in routine walking condition [4-7]. EF are heterogeneous cognitive functions [8]. Based on Miyake's model, executive functions-mental set may be divided in 3 main separate executive subdomains (ESD), which are information updating and monitoring, mental shifting and cognitive inhibition [8]. Little is known about the association between these ESD and STV among healthy participants [7]. Safe gait requires to analyse an important flow of visual, vestibular and proprioceptive information, and to update these information