Objective:

To describe chorea severity over time in individuals with Huntington disease (HD) stratified by Total Functional Capacity (TFC).

Background:

Chorea, the most common motor symptom in HD, negatively affects quality of life and TFC. Addressing chorea is crucial to reduce the burden of motor symptomatology in HD. Chorea has been reported to increase initially, plateau, and potentially decrease over time; however, longitudinal data assessing chorea severity by disease stage are limited. 

Design/Methods:

Participants were adults from Enroll-HD, a global, longitudinal, observational registry for individuals with or at risk for HD (data cut 2013–31 October 2020). The manifest population was stratified by baseline TFC score as a proxy for HD stage (TFC 7–‍13/stage 1–‍2 [early], 3–‍6/stage 3 [middle], 0–‍2/stage 4–‍5 [late]). Chorea severity was assessed by Total Maximal Chorea (TMC) score at baseline and at annual visits. Patients with ≥4 years of follow-up were selected for estimating chorea progression over time. 

Results:

The manifest population was grouped by HD stage: early, n=7441; middle, n=2330; late, n=1120. Baseline TMC scores (mean [SD]) increased as HD stage progressed (early, 8.0 [4.7]; middle, 10.4 [5.8]; late, 10.6 [6.9]). For participants with ≥4 years of follow-up (n=1271), TMC scores increased over time in early-stage HD (n=963; years 1–‍2, 8.5 [5.0]; years 2–‍3, 9.1 [5.3]; years 3–‍4, 9.5 [5.6]), but plateaued at high levels in middle- (n=222; 10.6 [5.3]; 10.6 [6.0]; 10.1 [5.7], respectively) and late-stage HD (n=86; 10.4 [6.6]; 9.8 [6.9]; 9.7 [6.2]). 

Conclusions:

Chorea severity increased in early-stage HD, and plateaued in middle- and late-stage HD. Chorea severity did not decrease longitudinally in any stage; however, the limited sample size for the follow-up period should be considered. These results support the need for increased awareness about the potential for persistent chorea in late-stage HD.