People with a history of childhood trauma are more likely to have a euphoric response to opioids, according to a study by scientists at the University of Exeter. The findings ‘may explain the link between childhood trauma and vulnerability to opioid use disorder, with implications for treatments and the prescribing of opioids medically’, say the researchers.
The strong link between early trauma and problematic drug use in adulthood is long established. The ongoing adverse childhood experiences (ACE) study has found that people who experienced four or more types of ACE – including physical or emotional neglect or physical, emotional or sexual abuse – are ten times more likely to be involved in injecting drug use (DDN, March, page 4).
The University of Exeter study – thought to be the first of its kind – compared the effects of morphine on 52 people, roughly half of whom had a history of severe childhood abuse and neglect, as measured by the widely used childhood trauma questionnaire. Those who had no history of childhood trauma were more likely to dislike the effects of the drug and report feeling nauseous or dizzy, while those who had experienced trauma ‘felt more euphoric and had a stronger desire for another dose’. Childhood trauma may ‘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’, the study concludes.
One explanation for the different responses in the two groups could be childhood trauma’s effect on the endogenous opioid system, a pain-relief process that is sensitive to chemicals such as endorphins – ‘our natural opioids’. Childhood trauma may ‘dampen’ this system, the researchers state. ‘When a baby cries and is comforted, endorphins are released – so if loving interactions like this don’t happen, this system may develop differently and could become more sensitive to the rewarding effects of opioid drugs,’ said lead author Dr Molly Carlyle. ‘There are high rates of childhood trauma in people with addictions. Our findings show that these sorts of experiences can actually change how certain drugs feel.’
The study was a randomised, double-blind trial where physically healthy participants aged between 18 and 65 attended two sessions a week apart and received either an active dose of morphine by injection or a ‘negligible’ control dose. While the morphine doses also increased pain threshold and tolerance, this ‘did not differ between the trauma and non-trauma groups’.
‘Our findings that people who have been traumatised as children are more likely to enjoy morphine might help to reduce stigma around heroin use,’ said leader of the research group, Professor Celia Morgan. ‘Many opioid addicts are people who were traumatised in early childhood, but it is still widely believed that addiction is a weakness and that addicts simply lack self-control. This research may be a step towards treating heroin addicts with more compassion, as we would children with histories of trauma. Our study also highlights the importance of interventions aimed at high-risk children and adolescents to protect against opioid use.’
A randomised, double-blind study investigating the relationship between early childhood trauma and the rewarding effects of morphine, published in Addiction Biology at https://onlinelibrary.wiley.com/doi/10.1111/adb.13047