Systematic Review on Emotion Recognition by Facial Expression and Prosody Speech in Patients with Parkinson's Disease

Perception of emotions through facial expression and speech prosody are known as effective emotional functions in the transmission of communication messages. Research on emotion recognition in patients with Parkinson's disease has less been noticed by the researchers. Therefore, the current study was conducted in order to review the literature on emotion recognition by facial expression and prosody speech in patients with Parkinson's disease. In the current review study, articles were located using specific keywords separately and in combination, including "Parkinson's disease, recognition, processing, perception, reception, vocal cue, prosodic cue, prosodic features, emotional voice and face, perceptual prosody, and facial expression". Articles were gathered from the following databases: PubMed, ScienceDirect, Wiley Online Library, Springer, Scientific Reports, and GoogleScholar. Out of 119 papers obtained, published between 1991-2017, 22 related articles were selected. Reviews showed different results; more than 80% of the studies related to perception of facial expression and  all studies related to prosody speech reported that emotion recognition in patients with Parkinson’s disease was weaker than that of control group, especially in negative control participants. More than 13% of the studies indicated no significant difference in such performance between the two groups, and the rest of studies reported variable results related to the conditions of patients associated with each study. According to the results, there were inconsistent findings in examining the relationship between Parkinson's disease and emotion recognition by facial expression or vocal prosody. The motor, cognitive or emotional injuries, which are commonly seen in the pathology of Parkinson's disease, appear to be not primarily related to deficits of emotional perceptions.