To use a large database to determine the difference in symptom profiles and disease progression between patients with early, typical, and late onset adult HD at different stages of disease.

Data were obtained from Enroll-HD. Adults with manifest HD were included. Age groups were defined as young onset (20-29 years), typical onset (30-50 years), and late onset (51+ years). Subjects in each group were categorized by TFC total score bins, from Stage I (least severe) to Stage V (most severe). Motor, cognitive, and behavioral symptoms were analyzed. We calculated descriptive statistics and Bonferroni p-value correction for pairwise comparison.

7,311 manifest HD subjects were included (612 young onset, 4,189 typical onset, and 2,510 late onset). The rate of decline in TFC score from baseline to second visit was significantly faster for young onset (-1.79 points) compared to the typical (-1.21, p<0.05) or late onset (-1.15, p<0.05) participants. Motor deficits were worse for late onset participants at early stages of HD, and worse for young onset participants at late stages. Young onset participants had a greater burden of behavioral symptoms at early and moderate stages of disease.

Younger age of onset is predictive of a faster functional decline for adults with HD when compared to those with typical and late age of onset. Motor and behavioral symptom profiles differ based on age of onset.