Facial emotion recognition in Parkinson's disease: Association with age and olfaction

Objective: The ability to recognize facial emotion expressions has been reported to be impaired in Parkinson's disease (PD), yet previous studies showed inconsistent findings. The aim of this study was to further investigate facial emotion recognition (FER) in PD patients and its association with demographic and clinical parameters (including motor and nonmotor symptoms). Method: Thirty-four nondemented PD patients and 24 age- and sex-matched healthy controls (HC) underwent clinical neurological and neuropsychological assessment, standardized olfactory testing with Sniffin' Sticks, and the Ekman 60 Faces Emotion Recognition Test. Results: PD patients had a significantly lower score on the total FER task than HC (p=.006), even after controlling for the potential confounding factors depression and apathy. The PD group had a specific impairment in the recognition of surprise (p=.007). The recognition of anger approached statistical significance (p=.07). Increasing chronological age and age at disease onset were associated with worse performance on the FER task in PD patients. Olfactory function along with PD diagnosis predicted worse FER performance within all study participants. Conclusion: Facial emotion recognition and especially the recognition of surprise are significantly impaired in PD patients compared with age- and sex-matched HC. The association of FER with age and olfactory function is endorsed by common structures that undergo neurodegeneration in PD. The relevance of FER in social interaction stresses the clinical relevance and the need for further investigation in this field. Future studies should also determine whether impaired FER is already present in premotor stages of PD.