Psychopathy is a
personality disorder characterized by specific interpersonal-affective deficits and social deviance often marked by reduced empathy and decreased affective response to the suffering of others. However, recent findings in community samples suggest that the somatosensory resonance to other's
pain measured with electroencephalography (EEG) is increased by psychopathic traits. This study aimed at comparing both the response to physical
pain and the observation of
pain being inflicted to another person in individuals with clinically significant psychopathic traits, namely patients with severe
narcissistic personality disorder (
NPD, n=11), and community controls (CC, n=13). The gating of somatosensory responses to a tactile steady-state stimulation (25 Hz) during the observation of
pain-evoking and non-painful visual stimuli of hands was measured using EEG. Pain thresholds were assessed with a quantitative sensory testing (QST) battery.
NPD compared with CC subjects showed similar thermal pain thresholds, but significantly higher
pain pressure thresholds (PPT). Significantly greater somatosensory gating (SG) during the anticipation and the observation of
pain in others was observed in
NPD compared with CC subjects, but this difference was not associated with differences in self-pain perception. SG to
pain observation was positively correlated with the Impulsivity-Egocentricity (IE) dimension of psychopathy. These findings demonstrated a stronger somatosensory resonance in the high psychopathic trait
NPD group that suggests an increased somatic representation of observed
pain despite lower dispositional empathy.