Revealed masks: Facial mimicry after oxytocin administration in forensic psychopathic patients

• Published in: Journal of psychiatric research Vol. 176; pp. 422 - 429
• Main Authors: Rijnders, Ronald J.P., van Boxtel, Anton, de Wied, Minet, van Honk, Jack, Kempes, Maaike M., Bos, Peter A.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2024
• Subjects: Adult; Antisocial Personality Disorder - physiopathology; Cross-Over Studies; Electromyography; Emotions - drug effects; Emotions - physiology; Facial Expression; Facial Muscles - drug effects; Facial Muscles - physiology; Facial Muscles - physiopathology; Facial Recognition - drug effects; Facial Recognition - physiology; Humans; Imitative Behavior - physiology; Male; Oxytocin - administration & dosage; Oxytocin - pharmacology; Photic Stimulation; Reaction Time - drug effects; Reaction Time - physiology; Young Adult
• ISSN: 0022-3956; 1879-1379; 1879-1379
• DOI: 10.1016/j.jpsychires.2024.06.032

Facial mimicry serves as an evolutionarily rooted important interpersonal communication process that touches on the concepts of socialization and empathy. Facial electromyography (EMG) of the corrugator muscle and the zygomaticus muscle was recorded while male forensic psychopathic patients and controls watched morphed angry or happy facial expressions. We tested the hypothesis that psychopathic patients would show weaker short latency facial mimicry (that is, within 600 ms after stimulus onset) than controls. Exclusively in the group of 20 psychopathic patients, we tested in a placebo-controlled crossover within-subject design the hypothesis that oxytocin would enhance short-latency facial mimicry. Compared with placebo, we found no oxytocin-related significant short-latency responses of the corrugator and the zygomaticus. However, compared with 19 normal controls, psychopathic patients in the placebo condition showed significantly weaker short-latency zygomaticus responses to happy faces, while there was a trend toward significantly weaker short-latency corrugator responses to angry faces. These results are consistent with a recent study of facial EMG responses in adolescents with psychopathic traits. We therefore posit a lifetime developmental deficit in psychopathy pertaining short-latency mimicry of emotional facial expressions. Ultimately, this deficit in mimicking angry and happy expressions may hinder the elicitation of empathy, which is known to be impaired in psychopathy. •Psychopathic patients are impaired in their short-latency mimicry of emotional facial expressions.•Weaker short-latency mimicry may be a biomarker of psychopathy.•Oxytocin does not enhance short-latency mimicry in psychopathic patients.