Effects of opioid antagonism on functional MRI correlates of explicit and implicit threat processing in healthy volunteers
Abstract
Background: We need to identify novel, tractable therapeutic targets for anxiety disorders. Converging evidence suggests the endogenous opioid system plays a role in modulating affective processing, but its contribution to regulation of threat processing in humans remains unclear.
Aims: We investigated the neural correlates of non-specific opioid antagonism on explicit and implicit regulation of threatening stimuli in healthy volunteers, using functional magnetic resonance imaging (fMRI).
Method: In a randomised, double-blind, placebo-controlled, crossover design, 38 healthy participants received the opioid antagonist naltrexone (50 mg) or placebo before completing two tasks during fMRI: (a) a cognitive emotional reappraisal task probing explicit regulation and (b) a face-viewing task probing implicit processing.
Results: Contrary to our hypothesis, we found naltrexone reduced distress ratings during the reappraisal task (p = 0.044) without impairing regulation success. Explicit regulation in the reappraisal task engaged lateral prefrontal regions similarly across drug conditions. However, naltrexone attenuated ventromedial prefrontal cortex, thalamus and caudate activation when viewing negative images. Naltrexone additionally altered ventromedial prefrontal cortex activity and in task-positive regions including right premotor area and frontal pole compared with placebo when viewing emotional faces. In particular, naltrexone increased left middle frontal gyrus activity when…
How strong is the evidence?
Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design. Reported size: 38 participants or records.
Read the paper
Related studies
- Preliminary Toxicity Analysis of 3DCRT versus IMRT on the High Dose Arm of the RTOG 0126 Prostate Cancer Trial
- Adaptive Radiotherapy for Head and Neck Cancer: Initial Clinical Outcomes from a Prospective Trial
- American Association of Physicists in Medicine Task Group 263: Standardizing Nomenclatures in Radiation Oncology
- Motion Management Strategies and Technical Issues Associated with Stereotactic Body Radiotherapy of Thoracic and Upper Abdominal Tumors: A Review from NRG Oncology
- High-dose-rate interstitial brachytherapy as a monotherapy for localized prostate cancer: treatment description and preliminary results of a phase I/II clinical trial
- Highly efficient training, refinement, and validation of a knowledge-based plan quality control system for radiotherapy clinical trials
Go deeper in Evidence Hub
Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.