P.018 Oculomotor learning as a biomarker in Huntington’s Disease (HD) patients

Abstract

Background: Huntington’s disease (HD) is an inherited neurodegenerative disorder associated with cognitive, psychiatric, and motor dysfunction. As a potential behavioural biomarker, experimental tasks assessing motor learning may thus provide a reasonable assay of HD onset and progression. The saccadic adaptation paradigm is a non-invasive, accessible method of assessing rapid learning in the oculomotor system. Evidence demonstrates that the thalamus and basal ganglia are important loci for saccadic adaptation, also known to exhibit neurodegenerative pathology before the onset of clinically observable symptoms in HD. Methods: 26 early symptomatic HD patients (Total Functional Capacity Score ≥ 10/13) and sex/age-matched controls were tested on a standard saccadic adaptation task. Eye movements were measured using infrared oculography. Learning dynamics of how quickly the participants adapted their saccade metrics were analysed using state learning models. Results: Initial findings demonstrate that the learning dynamics of HD patients are slower and more variable with respect to saccade amplitude compared to controls. Conclusions: These results demonstrate that motor learning dynamics as captured by a saccadic adaptation task reveal early motor dysfunction in HD, thus providing a discriminating tool to detect early pathological changes in HD patients. Further work is needed regarding applications as a biomarker for disease progression.