The experience of emotion in Parkinson's disease and normal aging: Assessing the roles of facial expressiveness and cognitive functioning

Abstract

This study was designed to assess the relationship between facial expression, self-reported emotional experience, and psychophysiological measures of emotion-related action tendencies. A secondary goal was to provide information regarding the relationship between psychophysiological action tendencies and cognitive functioning. Participants included normal elderly controls and individuals with Parkinson's disease (PD), a disorder associated with impaired involuntary facial expression and executive functioning. To assess whether decreased involuntary facial expression might alter the experience, action-tendency, or autonomic physiologic components of emotion, responses to emotion-eliciting slides were measured. Consistent with previous studies, increased corrugator EMG activity to negative slides and increased zygomatic EMG activity to positive slides were observed among controls. Individuals with PD were divided into two groups--"responders" and "non-responders"--based on facial EMG activity. "Responders" had a pattern of facial EMG consistent with controls, while "non-responders" were absent of significant involuntary facial emotion expression. Despite these differences in facial EMG activity, no group differences were observed on other measures of emotion components. Thus, compared to positive or neutral slides, negative slides elicited greater self-reported ratings of unpleasantness among control participants and both groups of PD participants. Across both groups, average startle responses were significantly smaller for positive compared to neutral, but not negative, slides. No significant effects of slide type on heart rate or SCR were observed in the primary analyses for any group. Regarding the second aim, analyses were conducted to assess the relationship between psychophysiological emotion measures and executive functioning. Several significant correlations were observed, but they were not consistent with a prior hypotheses. Implications of findings from these self-report, psychophysiological, and cognitive data for the study of emotion are discussed.