Objective: To examine the cortical control of gait and balance in HD under single-task (ST) and dual-task (DT) conditions compared to healthy controls using portable functional near infrared spectroscopy (fNIRS).

Background: Individuals with Huntington’s disease (HD) have difficulty multitasking while navigating their environment, so that previously automatic tasks may require more attentional resources to maintain mobility and prevent falls. Our understanding of the neural mechanisms underlying the relationship between impaired cognition and gait and balance in HD is minimal. fNIRS provides a noninvasive means to functionally image the brain under ecologically valid conditions to understand the neural underpinnings of impaired gait and balance in HD.

Method: Eighteen HD (56.2 + 9.8 yrs.) and 20 age-matched healthy control (HC) participants (57.4 + 11.2 yrs.) completed ST/ DT gait and balance testing wearing inertial sensors and fNIRS to collect spatiotemporal gait and balance variables with concurrent prefrontal (PFC) and posterior parietal (PPC) cortical activity monitoring. The cognitive DT for balance was the Controlled Oral Word Association test (COWAT) during 3, 30 sec trials and that for gait was the Digit Vigilance task during 3 trials of a one minute, 10-meter walk test.

Results: Individuals with HD had greater PFC and PPC activation during ST walking vs. HC (p= 0.01 and 0.049, respectively) but no difference in the DT condition. They had significantly lower PPC activity during an eyes open/DT balance condition compared to HC (p= 0.01). Unlike HC, there were no differences in PFC or PPC activation across balance conditions in HD, despite significantly worsening postural sway during DT conditions (p < 0.01). However, better COWAT scores were associated with increased PFC activation during DT sway in HD (p=0.03).

Conclusion: More attentional resources from the PFC appear to be necessary in HD during ST (but not DT) gait due to decreased gait automaticity. Together with our findings of reduced PPC activation in HD compared to HC during a DT balance task, we suggest that individuals with HD reached a recruitment ceiling at low difficulty levels (i.e. ST) and were thus unable to recruit beyond that ceiling when task difficulty increased (i.e. DT).

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MDS Abstracts - https://www.mdsabstracts.org/abstract/cortical-control-of-gait-and-balance-during-single-and-dual-tasks-in-huntingtons-disease-an-fnirs-study/