Visual scanning of the eye region of human faces predicts emotion recognition performance in Huntington's disease

Objective: Previous research has consistently shown that the ability to recognize emotions from facial expressions is impaired in Huntington’s disease (HD). The aim of this study was to examine whether people with the gene expansion for HD visually scan the most emotionally informative features of human faces less than unaffected individuals, and whether altered visual scanning predicts emotion recognition in HD beyond general disease-related decline. Method: We recorded eye movements of 25 participants either in the late premanifest or early stage of HD and 25 age-matched healthy control participants during a face-viewing task. The task involved the viewing of pictures depicting human faces with angry, disgusted, fearful, happy, and neutral expressions, and evaluating each face on a valence rating scale. For data analysis, we defined 2 regions of interest (ROIs) on each picture, including an eye-ROI and a nose/mouth-ROI. Emotion recognition abilities were measured using an established emotion-recognition task and general disease-related decline was measured using the UHDRS motor score. Results: Compared to the control participants, the HD participants spent less time looking at the ROIs relative to the total time spent looking at the pictures (partial η2 = 0.10), and made fewer fixations on the ROIs (partial η2 = 0.16). Furthermore, visual scanning of the eye-ROI, but not the nose/mouth-ROI, predicted emotion recognition performance in the HD group, over and beyond general disease-related decline. Conclusion: The emotion recognition deficit in HD may partly be explained by general disease-related decline in cognition and motor functioning and partly by a social-emotional deficit, which is reflected in reduced eye-viewing.