Abstract
Altered emotional processing, including reduced emotion facial expression and defective emotion recognition, has been reported in patients with Parkinson's disease (PD). However, few studies have objectively investigated facial expression abnormalities in PD using neurophysiological techniques. It is not known whether altered facial expression and recognition in PD are related. To investigate possible deficits in facial emotion expression and emotion recognition and their relationship, if any, in patients with PD. Eighteen patients with PD and 16 healthy controls were enrolled in this study. Facial expressions of emotion were recorded using a 3D optoelectronic system and analyzed using the facial action coding system. Possible deficits in emotion recognition were assessed using the Ekman test. Participants were assessed in one experimental session. Possible relationship between the kinematic variables of facial emotion expression, the Ekman test scores, and clinical and demographic data in patients were evaluated using the Spearman's test and multiple regression analysis. The facial expression of all six basic emotions had slower velocity and lower amplitude in patients in comparison to healthy controls (all Ps < 0.05). Patients also yielded worse Ekman global score and disgust, sadness, and fear sub-scores than healthy controls (all Ps < 0.001). Altered facial expression kinematics and emotion recognition deficits were unrelated in patients (all Ps > 0.05). Finally, no relationship emerged between kinematic variables of facial emotion expression, the Ekman test scores, and clinical and demographic data in patients (all Ps > 0.05). The results in this study provide further evidence of altered emotional processing in PD. The lack of any correlation between altered facial emotion expression kinematics and emotion recognition deficits in patients suggests that these abnormalities are mediated by separate pathophysiological mechanisms.
Highlights
Parkinson’s disease (PD) is a neurodegenerative disease characterized by motor and non-motor symptoms [1, 2]
Data of the two sides of the faces were pooled together for a subsequent between-group analysis showing no significant difference for the peak velocity and amplitude in various action units (AUs) examined between PD patients and healthy subjects (HS) (Table 2)
The analysis revealed that the kinematic variables were overall lower in PD patients than in healthy controls for all the six basic emotions analyzed (Table 2)
Summary
Parkinson’s disease (PD) is a neurodegenerative disease characterized by motor and non-motor symptoms [1, 2]. One important issue that has yet to be clarified is whether a relationship exists between facial emotion expression abnormalities and facial emotion recognition deficits in PD and whether these two deficits share the same underlying pathophysiological mechanisms [19, 21, 34]. This information would provide a deeper insight into the pathophysiology of altered emotional processing in PD patients. Few studies have objectively investigated facial expression abnormalities in PD using neurophysiological techniques It is not known whether altered facial expression and recognition in PD are related
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