Emotional and nonemotional facial expressions in people with Parkinson's disease

We investigated facial expressivity in 19 people with Parkinson's disease (PD; 14 men and 5 women) and 26 healthy controls (13 men and 13 women). Participants engaged in experimental situations that were designed to evoke emotional facial expressions, including watching video clips and holding conversations, and were asked to pose emotions and imitate nonemotional facial movements. Expressivity was measured with subjective rating scales, objective facial measurements (Facial Action Coding System), and self-report questionnaires. As expected, PD participants showed reduced spontaneous facial expressivity across experimental situations. PD participants also had more difficulty than controls posing emotional expressions and imitating nonemotional facial movements. Despite these difficulties, however, PD participants' overall level of expressivity was still tied to emotional experience and social context.