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<\/p>\nWhy do obesity drugs seem to treat so many other ailments?<\/p>\n
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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.<\/p>\n
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> \u2014 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.<\/p>\n 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<\/a>. \u201cAt the end of the day, the neurobiological system that is activated by rewarding substances \u2014 food, sex, drugs, rock and roll \u2014 it\u2019s the same system,\u201d 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.<\/p>\n Obesity drugs aren\u2019t always forever. What happens when you quit?<\/p>\n <\/a><\/p>\n The research is still in its early stages, scientists warn. \u201cWe first need to find out if it\u2019s efficacious and safe,\u201d says W. Kyle Simmons, a neuroimaging specialist at Oklahoma State University in Tulsa, who is leading a GLP-1 trial for alcohol reduction.<\/p>\n 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, \u201cit\u2019s a revolution\u201d.<\/p>\n Laboratory to limelight<\/p>\n It took some years for the current buzz around GLP-1 drugs in addiction medicine to build. Researchers originally developed them to control blood sugar in people with type 2 diabetes by mimicking the hormone GLP-1. Soon it became clear that the drugs could curb appetite and promote weight loss<\/a>, too. They act on hormone receptors located in the pancreas and gut \u2014 where they help to regulate blood sugar and signal fullness \u2014 but also in key regions of the brain that control reward and motivation, dialling down the urge for tasty, calorie-laden food.<\/p>\n By the early 2010s, Jerlhag Holm was wondering whether the drugs could blunt other urges. She published a trio of papers showing that they could dampen cravings in rats and mice hooked on alcohol2<\/a>, nicotine3<\/a> and stimulants such as amphetamine and cocaine4<\/a>. Her team also showed5<\/a> that GLP-1 therapy could reduce animal behaviours that resemble relapse, which is when people return to drugs after a period of abstinence.<\/p>\n Some people report anecdotally that GLP-1 drugs are helping them to quit long-standing nicotine addictions.Credit: Tolga Akmen\/AFP\/Getty<\/p>\n Yet her findings barely registered among addiction researchers, she says, and pharmaceutical companies showed no interest either. \u201cI was quite alone for a long time,\u201d says Jerlhag Holm.<\/p>\n But Lorenzo Leggio, a physician-scientist at the US National Institutes of Health in Baltimore, Maryland, noticed the work. He had also been following clues that GLP-1 might influence addictive behaviour and, in 2015, joined forces with Jerlhag Holm to uncover the first evidence of a connection between the hormone and alcohol dependence in humans. The team found that a common variant of the GLP-1 receptor gene was linked to heavier drinking6<\/a>.<\/p>\n Using post-mortem human brain tissue, Leggio\u2019s lab later showed that people with alcohol-use disorder have elevated levels of GLP-1 receptors in key reward-related regions of the brain7<\/a>. Leggio suspects that this reflects an adaptive response: alcohol dampens the body\u2019s GLP-1 production, and so the brain boosts expression of the hormone\u2019s receptors to preserve sensitivity to it in circuits that govern reward and motivation.<\/p>\n These results, together with a growing number of animal studies, solidified GLP-1\u2019s connection to addictive behaviour. Yet it was not until May 2023 that the story spilled into the public eye. The Atlantic magazine published an article about people taking semaglutide who said their urge to smoke or drink had faded. \u2018Did Scientists Accidentally Invent an Anti-addiction Drug?\u2019 it was headlined. \u201cThat was definitely a turning point,\u201d says Leggio, who suddenly found himself getting calls from journalists.<\/p>\n The first few rigorous trials, however, had largely disappointing results. A 2022 study in Denmark, led by psychiatrist Anders Fink-Jensen at the University of Copenhagen, found that weekly treatment with exenatide \u2014 a \u2018first-generation\u2019 GLP-1 compound used since 2005 to treat diabetes but never approved for weight loss \u2014 did not substantially reduce the number of heavy drinking days in people diagnosed with alcohol dependence8<\/a>. A 2023 trial in Switzerland likewise found that dulaglutide, another older GLP-1 drug, did not help people to quit smoking9<\/a>.<\/p>\n How obesity drugs quiet \u2018food noise\u2019 in the brain<\/p>\n <\/a><\/p>\n But other results suggested that the drugs might have an effect. In a trial10<\/a> involving 20 people with opioid-use disorder, led by Grigson and psychologist Scott Bunce, also at Pennsylvania State University, treatment with liraglutide \u2014 another first-generation GLP-1 drug \u2014 reduced opioid craving by roughly 40%. And when Fink-Jensen\u2019s team used functional magnetic resonance imaging (fMRI) to look at the brains of people taking exenatide in their clinical trial, they saw muted activity in reward-related regions when the participants viewed images of alcoholic drinks8<\/a>.<\/p>\n But the first-generation drugs tested in these preliminary studies are much less potent than agents such as semaglutide or tirzepatide. These second-generation compounds bind more tightly to the GLP-1 receptor, stay active in the body for longer and have shown greater benefits across a range of health conditions<\/a>. So, could these latest drugs change the behaviour of people struggling with substance misuse?<\/p>\n Blunting the buzz<\/p>\n That\u2019s what researchers are now examining in a raft of clinical trials with hotly anticipated results. Fink-Jensen and his colleagues have already tested whether the high dose of semaglutide approved for weight loss can cut alcohol intake in 108 people with alcohol-use disorder and obesity, in a clinical trial that wrapped up earlier this year. He says the results should be published in early 2026.<\/p>\n![\"\"](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2025\/12\/d41586-025-03911-x_27075824.jpg\"\/)
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