Last April, neuroscientist Sue Grigson received an e-mail from a man detailing his years-long struggle to kick addiction — first to opioids, and then to the very medication meant to help him quit.
The man had stumbled on research by Grigson, suggesting that certain anti-obesity medications could help to reduce rats’ addiction to drugs such as heroin and fentanyl. He decided to try quitting again, this time while taking semaglutide, the blockbuster GLP-1 drug better known as Ozempic. “That’s when he wrote to me,” says Grigson, who works at Pennsylvania State University College of Medicine in Hershey. “He said that he was drug- and alcohol-free for the first time in his adult life.”
Why do obesity drugs seem to treat so many other ailments?
Stories like this have been spreading fast in the past few years, through online forums, weight-loss clinics and news headlines. They describe people taking diabetes and weight-loss drugs such as semaglutide (also marketed as Wegovy) and tirzepatide (sold as Mounjaro or Zepbound) who find themselves suddenly able to shake long-standing addictions to cigarettes, alcohol and other drugs. And now, clinical data are starting to back them up.
Earlier this year, a team led by Christian Hendershot, a psychologist now at the University of Southern California in Los Angeles, reported in a landmark randomized trial that weekly injections of semaglutide cut alcohol consumption1 — a key demonstration that GLP-1 drugs can alter addictive behaviour in people with a substance-use disorder. More than a dozen randomized clinical studies testing GLP-1 drugs for addiction are now under way worldwide, with some results expected in the next few months.
Neuroscientists, meanwhile, are working out how the weight-loss drugs suppress addiction by acting on hormone receptors in brain regions that control craving, reward and motivation. They are finding that GLP-1 therapies help to blunt urges for alcohol, opioids, nicotine and cocaine through some of the same brain pathways that also quell hunger cues and overeating. “At the end of the day, the neurobiological system that is activated by rewarding substances — food, sex, drugs, rock and roll — it’s the same system,” says Roger McIntyre, a psychopharmacologist at the University of Toronto in Canada. And some researchers are testing whether, by influencing reward-related brain circuits, the drugs might help with dementia and depression as well.
Obesity drugs aren’t always forever. What happens when you quit?
The research is still in its early stages, scientists warn. “We first need to find out if it’s efficacious and safe,” says W. Kyle Simmons, a neuroimaging specialist at Oklahoma State University in Tulsa, who is leading a GLP-1 trial for alcohol reduction.
But some researchers and physicians are excited. No truly new class of addiction medicine has won approval from regulators in decades, says Elisabet Jerlhag Holm, an addiction biologist at the University of Gothenburg in Sweden. If GLP-1 drugs prove effective in bigger trials, she says, “it’s a revolution”.
Laboratory to limelight
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