Disgust and Huntington's disease

The disproportionate impairment for the recognition of facial expressions of disgust in patients with Huntington's disease (HD) forms a double dissociation with the impaired recognition of fear that has been reported in amygdala patients. The dissociation has generated discussion regarding the potential existence of neural substrates dedicated to the recognition of facial signals of specific emotions. The aim of this study was to establish whether the impairment for disgust in HD was restricted solely to the domain of facial perception, or whether HD patients also demonstrate impairment in other kinds of disgust. Fourteen HD patients and fourteen age and education matched healthy controls participated in seven disparate emotion processing tasks. (1) A measure of knowledge for the situational determinants of distinct emotions; (2) recognition of emotion expressed in nonverbal vocalisations; (3) recognition of the emotional content of explicit lexical stimuli; (4) recognition of emotional content in pictures of emotion scenes; (5) a disgust experience questionnaire; (6) a measure of olfactory hedonic responsiveness; (7) a measure of gustatory perception. While verbal aspects of disgust processing were preserved, parallel impairments were revealed for olfactory disgust, vocal disgust expressions, the classification of disgusting pictures, and declarative knowledge of disgust elicitors. The finding of impaired perception of disgust signalled through different input domains suggests that the inability to recognise the facial expression in this population reflects a fundamental problem with disgust processing.