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Neuropsychopharmacology. 2019 Jul;44(8):1456-1463. doi: 10.1038/s41386-019-0377-9. Epub 2019 Mar 31.

Intact responses to non-drug rewards in long-term opioid maintenance treatment.

Author information

1
Norwegian Centre for Addiction Research (SERAF), Faculty of Medicine, University of Oslo, Oslo, Norway. m.h.eikemo@medisin.uio.no.
2
Division for Mental Health and Addiction, Oslo University Hospital, Oslo, Norway. m.h.eikemo@medisin.uio.no.
3
Department of Diagnostic Physics, Oslo University Hospital, Oslo, Norway. m.h.eikemo@medisin.uio.no.
4
Norwegian Centre for Addiction Research (SERAF), Faculty of Medicine, University of Oslo, Oslo, Norway.
5
Division for Mental Health and Addiction, Oslo University Hospital, Oslo, Norway.
6
Department of Psychology, University of Oslo, Oslo, Norway.
7
The Intervention Centre, Oslo University Hospital, Oslo, Norway.

Abstract

Disruption of non-drug reward processing in addiction could stem from long-term drug use, addiction-related psychosocial stress, or a combination of these. It remains unclear whether long-term opioid maintenance treatment (OMT) disrupts reward processing. Here, we measured subjective and objective reward responsiveness in 26 previously heroin-addicted mothers in >7 years stable OMT with minimal psychosocial stress and illicit drug use. The comparison group was 30 healthy age-matched mothers (COMP). Objective reward responsiveness was assessed in a two-alternative forced-choice task with skewed rewards. Results were also compared to performance from an additional 968 healthy volunteers (meta-analytic approach). We further compared subprocesses of reward-based decisions across groups using computational modelling with a Bayesian drift diffusion model of decision making. Self-reported responsiveness to non-drug rewards was high for both groups (means: OMT = 6.59, COMP = 6.67, p = 0.84, BF10 = 0.29), yielding moderate evidence against subjective anhedonia in this OMT group. Importantly, the mothers in OMT also displayed robust reward responsiveness in the behavioral task (t19 = 2.72, p = 0.013, BF10 = 3.98; d = 0.61). Monetary reward changed their task behavior to the same extent as the local comparison group (reward bias OMT = 0.12, COMP = 0.12, p = 0.96, BF10 = 0.18) and in line with data from 968 healthy controls previously tested. Computational modelling revealed that long-term OMT did not even change decision subprocesses underpinning reward behavior. We conclude that reduced sensitivity to rewards and anhedonia are not necessary consequences of prolonged opioid use.

PMID:
30928994
PMCID:
PMC6785711
[Available on 2020-07-01]
DOI:
10.1038/s41386-019-0377-9

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