Measuring treatment effects on dual-task performance: a framework for research and clinical practice

Abstract

The relevance of dual-task walking to everyday ambulation is widely acknowledged, and numerous studies have demonstrated that dual-task interference can significantly impact recovery of functional walking in people with neurological disorders. The magnitude and direction of dual-task interference is influenced by the interaction between the two tasks, including how individuals spontaneously prioritize their attention. Therefore, to accurately interpret and characterize dual-task interference and identify changes over time, it is imperative to evaluate single and dual-task performance in both tasks, as well as the tasks relative to each other. Yet, reciprocal dual-task effects (DTE) are frequently ignored. The purpose of this perspective paper is to present a framework for measuring treatment effects on dual-task interference, specifically taking into account the interactions between the two tasks and how this can provide information on whether overall dual-task capacity has improved or a different attentional strategy has been adopted. In discussing the clinical implications of using this framework, we provide specific examples of using this method and provide some explicit recommendations for research and clinical practice.

Keywords: attention allocation; capacity sharing; cognition; cognitive-motor interference; gait rehabilitation; physical therapy; task prioritization.

Figure 1

Illustration of conceptual model for characterizing patterns of cognitive-motor dual-task interference. Figure is from Plummer et al. (2014), and adapted from conceptual framework of Plummer et al. (2013).

Figure 2

Plots showing interaction between two tasks and the patterns of dual-task interference pre and post intervention. DTE refers to Dual-task effect. DTEg is relative DTE on gait measure; DTEc is relative dual-task effect on cognitive measure. (A) Pre = mutual interference, post = improved gait interference (no change in cognitive interference); (B) Pre = mutual interference, post = improved gait interference (with improved cognitive interference); (C) Pre = gait interference with cognitive-priority trade off, post = improved gait interference (no change in cognitive DTE); (D) Pre = mutual interference, post = improved gait interference at cost to cognitive interference (worsened), therefore, no improvement but a change in strategy for dual-task performance. Data are hypothetical.