Separate brain circuits drive fentanyl addiction

Distinct brain circuits drive two key components of addiction to the synthetic opioid drug fentanyl, according to a new finding published in Nature (2024, DOI: 10.1038/s41586-024-07440-x ). The research significantly revises researchers' understanding of opioid addiction, and it points to approaches for more targeted treatment. Opioids are extremely addictive, and fentanyl —which is 50–100 times as potent as morphine or heroin and causes addiction in about a quarter of people who use it—is often deadly. In 2022, almost 82,000 people in the US died of opioid overdoses , the vast majority because of fentanyl. Researchers know that opioid addiction is driven both by positive reinforcement (a pull to the substance's euphoric effects) and by negative reinforcement (an effort to avoid deeply unpleasant withdrawal symptoms). Yet how opioids hook the brain isn't fully understood. Fentanyl and other opioid compounds bind to mu opioid receptors in neurons in a part of the