Eight motor-manifest HD participants were assessed for speech and gait at baseline visit and approximately eight weeks after they were treated with deutetrabenazine. For speech analysis, we utilized 1) perceptual ratings of dysarthria severity and speech intelligibility based on paragraph readings tasks, 2) acoustic measures of diadochokinetic rate (DDK) based on rapid syllable repetitions, and 3) kinematic measures (duration, range of motion, speed, trial-to-trial performance variability) of speech motor performance based on ten sentence repetitions. For gait analysis, average and coefficient of variation in stride speed, stride length, and percent of swing phase were measured during three 10m walk tests. The total chorea score in Unified Huntington’s Disease Rating Scale (UHDRS) was also obtained.

Preliminary findings showed mixed effects on perceptual ratings, DDK performance, and speech motor performance. Dysarthria severity and intelligibility changes were associated with speech motor performance changes, but not with DDK performance changes. In terms of gait assessments, three participants had faster stride speeds, five participants had longer strides, and one participant spent more time in the swing phase. Five participants had less variation stride speed, stride length, and time in the swing phase. Participants with the greatest reduction in the UHDRS chorea score also had the greatest improvements in speech and gait.

We speculate that deutetrabenazine may not benefit all HD patients equally in speech and gait function. With more data, trends in speech and gait metric may become more clear, which can provide insight into maximizing patients’ functional independence and quality of life.