Joint recognition-expression impairment of facial emotions in Huntington's disease despite intact understanding of feelings.

Patients with Huntington's disease (HD), a neurodegenerative disorder that causes major motor impairments, also show cognitive and emotional deficits. While their deficit in recognising emotions has been explored in depth, little is known about their ability to express emotions and understand their feelings. If these faculties were impaired, patients might not only mis-read emotion expressions in others but their own emotions might be mis-interpreted by others as well, or thirdly, they might have difficulties understanding and describing their feelings. We compared the performance of recognition and expression of facial emotions in 13 HD patients with mild motor impairments but without significant bucco-facial abnormalities, and 13 controls matched for age and education. Emotion recognition was investigated in a forced-choice recognition test (FCR), and emotion expression by filming participants while they mimed the six basic emotional facial expressions (anger, disgust, fear, surprise, sadness and joy) to the experimenter. The films were then segmented into 60 stimuli per participant and four external raters performed a FCR on this material. Further, we tested understanding of feelings in self (alexithymia) and others (empathy) using questionnaires. Both recognition and expression were impaired across different emotions in HD compared to controls and recognition and expression scores were correlated. By contrast, alexithymia and empathy scores were very similar in HD and controls. This might suggest that emotion deficits in HD might be tied to the expression itself. Because similar emotion recognition-expression deficits are also found in Parkinson's Disease and vascular lesions of the striatum, our results further confirm the importance of the striatum for emotion recognition and expression, while access to the meaning of feelings relies on a different brain network, and is spared in HD.