Loss of gait control assessed by cognitive-motor dual-tasks: Added value in detecting people at risk of developing Alzheimer's and Parkinson's diseases?

Abstract

Introduction Alzheimer's disease (AD) and Parkinson's disease (PD) are neurodegenerative diseases of increasing prevalence worldwide. In the absence of effective therapy, current research is focused on identifying individuals at high risk, who could be targeted in intervention trials. Today, the field of behavioral neuroscience has emerged as one of the most promising areas of research on this topic. Recently, it has been shown that the exacerbation of gait disorders in dual-task conditions, which involve the concurrent performance of a cognitive task while walking, is a characteristic feature of AD and PD. Objectives This review aims: – to summarize evidence supporting or refuting that the dual-task walking paradigm have added value for early detection of older people at risk for progression to AD or PD; – to propose new dual-task paradigms and markers for more accurate and earlier diagnosis of these diseases. Study selection The following inclusion criteria were used in this review: – used self-paced (comfortable) walking as the primary motor task; – reported gait parameters during both single- and dual-task performance, or dual-tasking effects on gait; – employed secondary cognitive tasks during dual-task walking. Results Dual-task-related gait changes precede the traditional clinical symptoms of AD and PD. Inhibition and flexibility are mostly impaired in preclinical AD and PD, respectively. Strategies in dual-task conditions may differentiate between preclinical AD and PD. A number of issues related to the application of dual-task methodology in gait (e.g., effect of type of cognitive task, choice of gait parameters, complementary use of linear and nonlinear measures) are discussed. Conclusion and perspectives We propose novel dual-task paradigms and markers based on the pathophysiological mechanisms that underlie gait disorders in each disease to advance our knowledge in this innovative area of research.