Happy facial emotional congruence in patients with relapsing-remitting multiple sclerosis.

Background: Emotion categorization has often been studied in the relapsing-remitting form of multiple sclerosis (RR-MS), suggesting an impairment in the recognition of emotions. The production of facial emotional expressions in RR-MS has not been considered, despite their importance in non-verbal communication.

Method: Twenty-five RR-MS patients and twenty-five matched controls completed a task of emotional categorization during which their faces were filmed. The stimuli were dynamic (sound or visual), expressed by adults (women or men), and expressing happy (laughing or smiling) or negative emotion. Two independent blinded raters quantified the happy facial expressions produced. The categorization task was used as a proxy for emotional categorization, while the happy facial expressions produced assessed the production of emotions.

Results: The main analysis indicated impaired categorization of RR-MS for happy stimuli selectively, whereas their happy facial expressions were not statistically different from those of the control group. More specifically, this group effect was found for smiles (and not laughter) and for happy stimuli produced by men. Analysis of individual patient profiles suggested that 77% of patients with impaired judgments produced normal facial expressions, suggesting a high prevalence of this dissociation. Only 8% of our samples showed reverse dissociation, with happy facial expressions significantly different from those of the control group and normal emotional judgments.

Conclusion: These results corroborated the high prevalence of emotional categorization impairment in RR-MS but not for negative stimuli, which can probably be explained by the methodological specificities of the present work. The unusual impairment found for happy stimuli (for both emotional categorization and facial congruence) may be linked to the intensity of the perceived happy expressions but not to the emotional valence. Our results also indicated a mainly preserved production of facial emotions, which may be used in the future sociocognitive care of RR-MS patients with impaired emotional judgments.