Cortical Correlates of Balance During Single and Dual Tasks in Huntington’s Disease: A Preliminary fNIRS Study

Objective Examine cortical activation patterns in Huntington’s disease (HD) under single-task (ST) and dual-task (DT) balance conditions compared to controls using portable functional near-infrared spectroscopy (fNIRS). Background Individuals with HD have difficulty multitasking while performing balance tasks, so previously automatic tasks may require more attentional resources to maintain stability and prevent falls. Our understanding of the neural mechanisms underlying the relationship between impaired cognition 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 balance in HD. Methods Eighteen HD (56.2 ± 9.8 years) and 20 age-matched control participants (57.4 ± 11.2 years) completed ST/ DT balance testing with eyes open (EO) or eyes closed (EC) wearing inertial sensors and fNIRS to collect spatiotemporal balance variables with concurrent prefrontal (PFC) and posterior parietal (PPC) cortical activity monitoring. The cognitive DT was the Controlled Oral Word Association Test during 3, 30-second trials. Results Individuals with HD had significantly lower PPC activity during the EO DT condition compared to controls ( P = .007). Unlike controls, there were no differences in PFC or PPC activation across balance conditions in HD, despite significantly worsening postural sway during DT conditions ( P < .0001). Conclusion Our findings suggest that individuals with HD are unable to increase cortical activation during challenging DT conditions suggesting a recruitment ceiling was reached during ST conditions. Furthermore, individuals with HD may not be able to increase cortical recruitment in response to increasing task difficulty.