Chronic non-medical prescription opioid use and empathy for pain: Does pain make the difference?

Non-medical prescription opioid use (NMPOU) is at the heart of the opioid epidemic in the United States. Although chronic opioid use is commonly accompanied by deficits in social functioning, little is known about the impact of chronic NMPOU on social cognitive functions. Social neuroscience models suggest that empathy activates similar or even equivalent neural structures as those underpinning the first-hand experience in that emotional state (e.g., pain). Therefore, we measured subjective and psychophysiological responses during an empathy-for-pain task in 23 individuals with NMPOU, objectively confirmed by hair and urine testing, and compared them with 29 opioid-naive healthy controls. NMPOU individuals showed lower other-related and self-related unpleasantness ratings when seeing others in pain than controls. No differences between the control and NMPOU group were found in skin conductance responses and heart rate variability (HRV) assessed by root mean square of successive differences (RMSSD) in response to the task. However, RMSSD-HRV was strongly negatively correlated with self-related unpleasantness and craving in the NMPOU group. A subsequent mediation analysis showed a total effect of RMSSD-HRV on self-related unpleasantness with no mediation of craving. This indicates that stronger emotion regulation indexed by high RMSSD-HRV might have downregulating effects on sharing others' pain in NMPOU individuals but not in healthy controls, which was further accompanied by decreased ratings of personal distress and empathetic concern. These results contribute to a better understanding of social functioning in chronic opioid users, suggesting adequate emotion regulation and empathy trainings as therapeutic targets for future interventions of opioid use disorders and long-term pain treatment with opioids.