Predictors of Working Capacity Changes Related to Huntington's Disease: A Longitudinal Study

Background: Huntington's disease (HD) is an inherited neurodegenerative disorder that is characterized by motor, cognitive, and psychiatric symptoms. Although 65% of HD expanded gene carriers report changes in employment as the first functional loss, little is known about the predictors leading to changes of working capacity. Given the impact on quality of life, understanding of these factors is of great clinical value. Objective: This study evaluates disease specific characteristics and their predictive value in loss of working capacity in HD. Methods: Longitudinal data was collected through the worldwide observational study (Enroll-HD), with 15,301 participants in total and 2,791 HD and healthy control participants meeting the inclusion criteria. Changes in working capacity were analyzed by means of a survival analysis. Predictive values of demographic factors and clinical characteristics were assessed for premanifest and manifest HD through Cox regressions. Results: HD expanded gene carriers, manifest and premanifest combined, had a 31% chance of experiencing changes in employment after three years, compared to 4% in healthy controls. Apathy was found to be the most crucial determinant of working capacity changes in premanifest HD, while executive and motor dysfunction play an important role in manifest HD. Conclusion: HD expanded gene carriers are more likely to lose working capacity compared to healthy controls. Disease progression, altered motor function, cognitive decline, and in an early stage of the disease apathetic symptoms are indicative of negative changes in working capacity. Clinicians should recognize that early disease related changes, especially apathy, can affect working capacity.