Background Irritability, depression, and apathy are frequently reported neuropsychiatric symptoms of Huntington's disease (HD).

Aim This study investigated the course of irritability, depression, and apathy in HD during a 2-year follow-up period.

Methods In 121 HD mutation carriers the presence of irritability, depression, and apathy was measured with the Problem Behaviours Assessment. Multivariate linear regression analysis was performed to assess their relationships with the change of the motor score of the Unified Huntington's Disease Rating Scale in pre-motor symptomatic (n=46) and motor symptomatic mutation carriers (n=75).

Results The median depression score of all participants decreased (p=0.002), whereas irritability and apathy scores did not change significantly. In the total group of mutation carriers, borderline significant associations were found between an increase in motor symptoms on the one hand, and an increase in irritability and a decrease in depression on the other hand (both p=0.05). Only in the initially pre-motor symptomatic mutation carriers, an increase in motor symptoms was significantly related to an increase in irritability (p=0.02).

Conclusion An increase in motor symptoms in initially pre-motor symptomatic mutation carriers is related to an increase in irritability, which may be an early and sensitive marker for disease progression.