Background Quantitative digital motor assessments such as the Q-Motor Finger Tapping have been shown to detect progression (TRACK-HD) and drug effects in multiple clinical trials. We here report cross-sectional results of the novel Isometric Force Matching task that had been introduced in the TRACK-HD study as part of the Q-Motor assessment battery to assess grasping force in a more defined environment.

Aims To evaluate the potential of the Q-Motor Force Matching task as quantitative endpoint to objectively assess motor dysfunction in clinical studies in HD.

Methods A target force level and current sensor force level were displayed on a computer screen. Participants of the TRACK-HD study (year 2011, gene carriers=220, controls=110) were instructed to grasp a force sensor-equipped device, which was firmly attached to a table surface, in precision grip, and to adjust the applied force to best match the displayed target force level using visual feedback. For group comparisons, we used a CAG-Age dependent parametric survival model (Langbehn 2004).

Results Q-Motor Force Matching shows high correlations with clinical scales, CAG-Age product scores and imaging variables. Differentiation between gene carriers and non-gene carriers was very good (p<0.001) for groups of gene carriers with a Survival Score of <=0.75.

Conclusions We could show that Q-Motor Isometric Force Matching assessment is feasible in multicenter clinical studies in HD and can differentiate between patient groups. The task design allows to also add cognitive challenges, which we want to explore in further experiments, along with longitudinal performance.

Acknowledgment TRACK-HD study team and CHDI-Foundation