Weight loss drugs have become increasingly popular in recent years for the treatment of obesity and type 2 diabetes, but does their purpose end there? Recent research on addiction suggests otherwise.
Semaglutide and tirzepatide, more commonly known by their brand names Ozempic and Mounjaro, are a class of drugs known as incretin mimetics used to treat obesity and type 2 diabetes. Semaglutide (Ozempic) is a glucagon-like peptide-1 receptor agonist which mimics the GLP-1 hormone created in our gut that signals to the brain that we are full. Tirzepatide (Mounjaro) is a dual action agonist, targeting the both GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) receptors. GIP is a hormone released by the small intestine that stimulates insulin secretion to regulate blood sugar. A new triple agonist, Retatrutide, is in its third phase of clinical trials and works by targeting GLP-1, GIP and Glucagon receptors, which increases energy expenditure.
Individuals who have been prescribed these weight loss drugs have not just noticed a change in their eating habits, but also in their drinking and smoking habits, which was a pleasant surprise to many. This is due to the fact that the rewarding feeling you get from indulging in your favourite food or having a few pints stems from the same chemical – dopamine.
The feel-good neurotransmitter (chemical messenger) is released by the mesolimbic dopamine pathway in the brain. When you participate in an activity or consume something that the brain recognises as rewarding, the Ventral Tegmental area (VTA) activates and releases dopamine into the nucleus accumbens – the brain’s pleasure and motivation centre. The brain then associates this behaviour with the release of dopamine, so the desire for you to do it again occurs. When you consume drugs or drink alcohol, the amount of dopamine released is significantly higher in comparison to the amount released from healthier behaviours, which is why repeated usage can lead to an addiction.
Currently, the treatment for individuals with substance misuse disorders (SUD) and alcohol misuse disorder (AUD) use a combination of therapy and detoxification, in addition to medication-assisted treatment. The current medications approved for treatment are methadone, buprenorphine, and naltrexone, which are used to reduce withdrawals and cravings. These medications significantly reduce the risk of overdose and death; however, some do come with risks, for example methadone, used to treat opioid addictions, has a high misuse potential. Researchers are currently investigating the use of GLP-1s as a treatment for such addictions, and hope in future that they could be used as a complimentary aspect of the standard treatment used to tackle both substance misuse and alcohol misuse disorders.
Research investigating the effectiveness of using GLP-1s in the treatment of addictions began in the early 2010s, however in recent years the amount of research has grown significantly. Numerous clinical trials are currently in progress exploring the effect of GLP-1s on the use of substances including alcohol, nicotine, and opioids. One of the first GLP-1s to be used in this clinical context was Exendin-4 (Exenatide), a 39-amino acid peptide originally isolated from Gila monster venom which acts as a long lasting GLP-1 receptor agonist. When given to rats who were previously seen self-administering cocaine, there was a 40% reduction in drug seeking behaviour, and when given to mice a reduction in alcohol- induced locomotor stimulation and dopamine release was observed. Researchers partially attribute the promising results to an increase in the activation of inhibitory GABA neurons, a neurotransmitter responsible for reducing neuronal excitability throughout the central nervous system. Other GLP-1s such as semaglutide and liraglutide are also showing promising results. A small clinical trial with participants undergoing opioid withdrawal reported a 40% reduction in cravings compared to a placebo.
A large amount of anecdotal evidence is also readily available, with hundreds of first-hand accounts from individuals who have been prescribed weight loss drugs or are currently taking part in clinical trials (Retatrutide) mentioning reduced cravings for alcohol and nicotine.
More research is needed to establish GLP-1s as a treatment for addiction, especially due to conflicting studies which have shown no significant effect on individuals suffering from various addictions. Larger clinical trials are currently in progress to determine proper dosage, establish efficacy and to investigate long-term safety and adverse side effects.
Despite this research still being in its early stages, the promising results indicate that weight loss drugs may be used in the future as an addition to the treatment of alcohol and drug misuse disorders which affected over 300,000 people in England alone last year.