A randomised, double-blind study investigating the relationship between early childhood trauma and the rewarding effects of morphine.

Experiences of childhood trauma (abuse and neglect) are disproportionately higher in those with opioid use disorder (OUD). Childhood trauma may affect the reinforcing and rewarding properties of opioid drugs and responses to pain, potentially via developmental changes to the endogenous opioid system. This has been supported by preclinical research, yet this has not been investigated in non-addicted humans. Physically healthy participants with either a history of severe childhood trauma or no previous history of childhood trauma attended two sessions where they received either an intramuscular active dose of morphine (0.15 mg/kg) or a very low dose control (0.01 mg/kg) in a randomised, double-blind crossover design. Sessions were held 1 week apart. Participants' physical pain threshold and tolerance were measured pre- and post-drug administration using the cold water pressor test, alongside acute subjective and behavioural responses over 2.5 h. The trauma group reported liking the effects of morphine, feeling more euphoric and wanting more of the drug over the session, as well as feeling less nauseous, dizzy, and dislike of the effects of morphine compared to the non-trauma comparison group. Morphine increased pain threshold and tolerance, yet this did not differ between the groups. Childhood trauma may therefore sensitise individuals to the pleasurable and motivational effects of opioids and reduce sensitivity to the negative effects, providing compelling evidence for individual differences in opioid reward sensitivity. This may explain the link between childhood trauma and vulnerability to OUD, with consequent implications on interventions for OUD, the prescribing of opioids, and reducing stigmas surrounding OUD.

Greater empathy in MDMA users.

BACKGROUND: 3,4-Methylenedioxymethamphetamine (MDMA) is widely known for its positive acute effects on social behaviour, such as increasing empathy, whilst also attenuating the negative impact of social exclusion. However there is a scarcity of research that investigates the long-term impact of recreational MDMA use on these fundamental social processes. METHOD: Sixty-seven individuals were split into three groups based on their drug-use history: poly-drug MDMA users ( n = 25), poly-drug users who do not use MDMA ( n = 19), alcohol-only users ( n = 23), and were tested in an independent groups design. Participants completed both a self-report measure of emotional and cognitive empathy, along with the Multifaceted Empathy Task - a computerised assessment of empathy - and the Cyberball Game - a social exclusion paradigm. RESULTS: MDMA users had significantly greater subjective emotional empathy, and greater cognitive empathy on the computer task compared with the poly-drug users who do not use MDMA. There were no significant differences in subjective responses to social exclusion between the groups. Indices of MDMA use did not correlate with empathy. CONCLUSIONS: Long-term MDMA users in this sample exhibited normal psychosocial functioning in regard to empathy and social pain and had higher subjective emotional empathy. This conflicts with previous suggestions that moderate, long-term MDMA use may cause heightened social distress, and is further evidence of the safety of the drug, which is relevant to considerations of its therapeutic use.