Is pain empathy associated with pain indices and trauma history? A comparison between patients receiving methadone maintenance treatment and healthy controls.

Background: To study whether pain empathy and theory of mind (ToM) are related to pain indices and trauma experience, we studied opioid users receiving methadone maintenance treatment (MMT), a population with a history of traumas and a high prevalence of chronic pain. Methods: MMT patients (n = 53), substance abuse-free, with no impaired cognition (Montreal Cognitive Assessment (MoCA) ≥24), were compared to healthy controls (HC) matched by age and gender (n = 66). All participants were assessed using Reading the Mind in the Eyes (RMET) for ToM, empathy (Interpersonal Reactivity Index [IRI], Empathy Quotient Scale for Adults [EQ60]), and Pain Empathy [PE task]). An algometer was used for pain pressure threshold, and supra-pain threshold was rated using a visual analog scale (VAS). Catastrophizing, McGill pain, Negative life events (NLE), and MoCA questionnaires were administered. Substance abuse was tested in the urine of MMT patients and self-reported by HC. Results: MMT, compared to HC, were less educated with more NLE and a lower RMET (logistic regression). Groups had comparable empathy and pain indices, except for higher supra-threshold VAS rating and catastrophizing in univariate analyses. Pain empathy (PE) correlated with NLE in HC, and in MMT, with catastrophizing, which correlated with NLE, perceived stress, and pain intensity. Higher empathy was observed in 18 participants with a history of sexual abuse (83.3 % belong to the MMT group). Conclusions: Pain Empathy was found to be associated with personal suffering experience in both groups, as reflected by correlations with NLE in HC and with catastrophizing, which correlates with NLE, stress, and pain intensity, in MMT.