Blunted emotion judgments of body movements in Parkinson's disease

Abstract

Some of the behavioral disorders observed in Parkinson's disease (PD) may be related to an altered processing of social messages, including emotional expressions. Emotions conveyed by whole body movements may be difficult to generate and be detected by PD patients. The aim of the present study was to compare valence judgments of emotional whole body expressions in individuals with PD and in healthy controls matched for age, gender and education. Twenty-eight participants (13 PD patients and 15 healthy matched control participants) were asked to rate the emotional valence of short movies depicting emotional interactions between two human characters presented with the "Point Light Displays" technique. To ensure understanding of the perceived scene, participants were asked to briefly describe each of the evaluated movies. Patients' emotional valence evaluations were less intense than those of controls for both positive (p < 0.001) and negative (p < 0.001) emotional expressions, even though patients were able to correctly describe the depicted scene. Our results extend the previously observed impaired processing of emotional facial expressions to impaired processing of emotions expressed by body language. This study may support the hypothesis that PD affects the embodied simulation of emotional expression and the potentially involved mirror neuron system.

Figure 1

Boxplots comparing valence judgments of PD and HC participants, presented respectively as a function of the two main valence conditions (positive/negative) (top) and for each negative emotion separately (bottom). Note that the used subjective scale went from − 5 (very negative) to 5 (very positive). The y axis limits are [0;5] for positive emotions and [− 5;0] for negative emotions, except for sadness (y axis [− 5;5]). P-values (p) and effect size (r) of the Wilcoxon Mann–Whitney tests are indicated in the plot. PD = Parkinson’s disease patients, HC = Healthy controls.

Figure 2

Experimental paradigm: valence judgments of emotional body movements, using the technique “Point-Light displays”. t0 = 3-s silent movies depicting whole-body movements presented with PLD; t1 = valence judgment task; t2 = description task.