Personality traits and sensitivity to pain in male chronic opioid addicts

Objective: Previous evidences concerning pain mechanisms, long-term opioids use, and personality traits evolve the possibility that pain perception and opioid abuse are two related phenomena and there is a need to take into account the specific personality traits as well, in examining the relationships among them. Opioid addicts (OAs) have been shown to exhibit different personality traits and pain perception as compared with healthy subjects. The aim of the present study was to examine the relations between personality traits and pain perception among in-treatment OAs in comparison with controls. Design: Participants (54 OAs, 59 controls), all males, were exposed to the cold pressor test and were evaluated for latency of pain onset (seconds); pain intensity (0-100 visual analogue scale [VAS)]); and pain tolerance (time for hand withdrawal). Personality traits were evaluated using Cloninger's Tridimensional Personality Questionnaire, TPQ; harm avoidance, HA; reward dependence, PD; novelty seeking, NS. Results: In comparison with controls, OAs exhibited longer latencies, lower VAS scores, and shorter tolerance, and significantly higher NS, higher HA, and lower RD. Control group, but not OAs, showed a significant positive correlation between HA and VAS (r = 0.31, p = 0.02) and significant negative correlation between HA and tolerance (r = -0.29, p = 0.03). Conclusions: It is concluded that in contrast to healthy population, personality traits, as measured by the TPQ do not predict pain perception in OAs.