Stride Time Variability During Dual Tasks Shows Potential as Diagnostic, Prognostic Biomarker of Functional Gait Disorders

Michele Tinazzi, MD, PhD

When comparing patients with functional gait disorders (FGDs) and health controls (HCs), a study showed that FGDs had poorer gait performance and less automaticity and steadiness. In overall dual-task effects, or percent changes in gait measures from single to dual tasking, only gait performance, but not stride time variability was affected, suggesting that stride time variability could be a potential diagnostic and prognostic biomarker.

Senior author Michele Tinazzi, MD, PhD, professor of neurology, University of Verona, and colleagues wrote, “Besides improving their ecological validity, standardizing research methodologies can yield a better understanding of dual-task related gait changes in different populations and advance our understanding of their neural mechanisms and gait control.

In the study, the group of investigators aimed to answer, how do different dual task paradigms shape spatio-temporal gait patterns in FGDs? To do so, 29 individuals with FGDs (mean age, 43.48 [±15.42] years) and 49 HCs underwent spatio-temporal gait analysis during a single task and during performance on a motor, a cognitive, and a visual-fixation dual-task. These analyses were performed at a self-selected speed on a 7.92-m electronic walkway (GAITRite).

The single-task entailed walking at a self-selected comfortable speed, while the motor dual-task consisted of walking down the walkway while executing prono-supination movements with the right hand on the right thigh at 1 Hz without auditory cues. The cognitive dual-task consisted of serially subtracting 7 starting from 100, while the visual-fixation task consisted of walking down the walkway while focusing on a "destination-focused" fixation circle placed at eye level in front of the individual. Each trial was repeated 3 times to obtain a mean of gait parameters and to minimize bias.

Between the 2 groups, there were no differences in age (P = .097) or sex (P = .31). In terms of patient characteristics and raw spatio-temporal gait measures, which included gait speed, stride length, and stride time variability, were all statistically significant for the main effect of task and group (all P <.04). Patients with FGDs demonstrated significantly poorer gait performance (P <.019). Additionally, no significant task x group interactions were found, indicating that dual tasks had similar effects in both groups.

In the post-hoc dual-tasking effect analysis, the main effect of the task continued to be significant for all measures (all P <.04). In contrast, the effect of the group was significant only on gait speed (F[1,76], 4.456; P = .038) and stride length (F[1,75], 8.447; P = .005), not stride time variability, which indicated slower gait speed and shorter stride length on the secondary task for patients with FGDs. Similarly, there was only a significant Task x Group interaction seen for gait speed and stride length.

Dual-tasking treatment effects were higher on the cognitive dual-task and motor dual-task in the post-hoc analysis for patients with FGDs relative to HCs. This was not observed on the visual fixation dual-task for gait speed and stride length. Similarly, higher dual-task treatment effects were observed for motor and cognitive dual-tasks for patients with FGDs (all P <.02), but not with the visual fixation dual-task when compared with HCs. Furthermore, no significant Task x Group interaction was observed for the dual-task treatment effects on stride time variability (P = .283), indicating that the effects of dual tasking were similar in the 2 groups.

"Our findings have implications for clinical practice," Tinazzi et al wrote. "Understanding the high-level attentional role in the pathophysiology of disturbances can help improve diagnosis and hypothesize potential directional intervention by practicing the executive domain through dual tasking to plan personalized intervention. Of note, the three types of dual-tasking (motor, cognitive, visual) should be integrated with the assessment of FGDs to explore the effects of different types of attentional focus. Future studies should explore the heterogeneity of FGD phenotypes and the specific gait phenotype correlates."

REFERENCE
1. Gandolfi M, Fiorio M, Geroin C, et al. Dual tasking affects performance but not automaticity in functional gait disorders: a new diagnostic biomarker. Parkinsonism Relat Disord. Published online January 24, 2023. doi:10.1016/j.parkreldis.2023.105291