IF YOU TAKE a GLP-1 agonist like Ozempic or Zepbound, you can see changes to your waistline and your blood sugar within weeks. What might be less obvious is how the drug is affecting your brain. Research suggests these popular weight-loss medications can influence everything from daily behavior to risk of age-related memory loss, and neuroscientists are working overtime to discover exactly how these drugs affect the brain.
“It is a hot topic,” says Kevin Williams, Ph.D., a neuroscientist at the University of Texas Medical Branch. “If you can understand how these drugs are accessing the brain and where they are acting, then potentially that could guide future drug development to be able to better target these regions.”
But how, exactly, can they affect your brain? Experts answer your top questions:
Do GLP-1s Reduce Food Noise?
FOOD NOISE ISN’T a grumbling in your stomach when you’re hungry. It happens when you feel like your life revolves around food.
“Some examples that people cite are not being able to focus during a meeting because you’re thinking about the pizza that will be served sometime during the meeting, or going to an event with your friends and loved ones and not being able to think of something else other than the food,” says Daisuke Hayashi, M.S., a Ph.D. candidate and nutrition researcher at Penn State University.
We all react to environmental cues that tell us it’s time to eat, like the scent of fries wafting through the air. These cues stimulate your brain’s mesolimbic reward pathway. You crave food, seek it, and feel pleasure eating it. However, some people are extra reactive to food cues.
“It’s like your brain is doing all of the things that it has evolved to do, but at a much higher level,” says Hayashi. “This is likely to help explain why some people are more susceptible than others to developing obesity, binge eating disorder, and maladaptive eating behaviors.”
When people take GLP-1s, they often report that their food noise goes away. For some, it’s an a-ha moment because they realize for the first time how intrusive the food noise used to be. GLP-1s can help by slowing down gastric emptying and increasing your release of the hormone insulin to help you feel full longer. Research also suggests these drugs might act on GLP-1 receptors in your brain to reduce cravings.
If you think you struggle with food noise, tell your healthcare provider and ask for a referral to a registered dietitian.
“It’s really important that patients are well educated by a dietitian when they make those changes to their lifestyle,” says Hayashi. “Just changing how they respond to food cues without providing the appropriate support for lifestyle change can backfire.”
Do GLP-1s Slow Down Brain Aging?
EVIDENCE IS STACKING up that GLP-1 agonists might help your brain stay sharp as you age. New research in the journal International Immunopharmacology showed that obese people treated with a GLP-1 agonist had a 37 percent lower risk of Alzheimer’s disease, a 41 percent lower risk of Lewy body dementia, and a 56 percent lower risk of vascular dementia than people in similar health who didn’t take these medications. People who took semaglutide (Ozempic) also had a 43 percent lower risk of Parkinson’s disease.
In a recent study in the New England Journal of Medicine, the GLP-1 lixisenatide (Adlyxin) slowed the progression of early Parkinson’s Disease.
“Prognosticating Parkinson’s is not possible, and some people go on to have a devastating course,” says Roger S. McIntyre, M.D., FRCPC, professor of psychiatry and pharmacology at the University of Toronto. “If you have a treatment that is modest in its ability to acutely affect symptoms but can really meaningfully alter the long-term course, that’s a win.”
“Ozempic and its cousins might also IMPROVE INSULIN SIGNALING in your gray matter, PROTECTING THE BRAIN CELLS you use for thinking.”
Ozempic and its cousins started as type 2 diabetes drugs, and they help your body use insulin to regulate blood sugar. They might also improve insulin signaling in your brain’s gray matter, protecting the brain cells you use for thinking, says Michal Schnaider Beeri, Ph.D., director of the Herbert and Jacqueline Krieger Klein Alzheimer’s Research Center at Rutgers University. “Insulin is critical to brain function,” says Beeri.
In addition, GLP-1s might assist the blood vessels that bring nutrients and oxygen to your brain. “These drugs work in our vasculature,” says Stefan Trapp, Ph.D., professor of autonomic neuroscience and metabolic disease at University College London. “They might improve the blood flow to our brain, and that would be a way of protecting the brain and reducing cell death.”
Do GLP-1s Help You Recover From Addiction?
“I’M SEEING THIS clinically, anecdotally, and I’m glad that we have some studies on this as well, that people who have an alcohol addiction or drug addiction have a reduction in both of those whenever they start taking these medications,” says Layla Abushamat, MD, MPH, an endocrinologist at Baylor College of Medicine.
GLP-1s could help you reduce alcohol intake, quit smoking or vaping, or even cut the risk of opioid overdose, research suggests.
One explanation is that these medications might help to normalize overactive reward circuits in your brain to make vices less enticing, according to a study review published in Physiology and Behavior. Reward circuits that release the feel-good neurotransmitter dopamine play a big role in food craving, and “they are activated and overactivated during addiction as well,” says Trapp.
If you struggle with addiction along with obesity or type 2 diabetes, tell your doctor so they can consider how a GLP-1 might fit into your treatment mix.
Do GLP-1s Boost Your Mental Health?
MAYBE. IN A a recent study review, researchers in Italy concluded that GLP-1s might reduce depression symptoms and suicidal thoughts. However, some users have also reported increases in depression, anxiety, and suicidal thoughts.
“The effects of GLP-1 receptor agonists on depression are controversial,” says study author Maria Letizia Petroni, MD, MPhil, associate professor in dietetics and clinical nutrition at the University of Bologna.
Here are some reasons why the drugs might help you feel happier. GLP-1 agonists might make neurons—nerve cells in the brain—more resilient. “In the brain of an adult living with depression, something has gone awry with the plasticity and the protection of the neuronal population,” says McIntyre.
A review of six studies found that people with type 2 diabetes who were treated with GLP-1 agonists reduced depressive symptoms more than people on other treatments. By lowering blood sugar, the drugs might protect tiny blood vessels in the brain from harm, the researchers say.
Another potential benefit is that by taking a GLP-1, you might be able to counter the weight-gain-inducing effects of other medications you take for mental health. “Very often our medications, unfortunately, in psychiatry, cause a lot of weight gain,” says McIntyre.
The flip side is that not everyone gives these drugs a glowing review when it comes to mental health. One recent study of reports from the FDA’s Adverse Event Reporting System database found that less than 5 percent of complaints about GLP-1s were related to psychiatric symptoms, but GLP-1s were more likely than other medications to be linked to nervousness, stress, eating disorders, fear of injection, insomnia, binge eating, fear of eating, and self-induced vomiting. It’s unclear whether the drugs contributed to these problems or whether these side effects were linked with a preexisting psychiatric disorder, the researchers say.
So, what should you expect?
“In the vast majority of patients an improvement of mental symptoms is expected following weight loss obtained with behavioral treatment associated to GLP-1 receptor agonists,” says Petroni. “Nevertheless, in some instances a worsening of depressive symptoms may occur as a consequence of weight loss (well documented in series of bariatric surgery patients) and/or as a possible side effect of GLP-1 receptor agonist therapy.”
Before taking these drugs, make sure your healthcare provider knows about any mental health diagnoses or concerns you have and any medications you take. Ask for referrals for intensive behavioral treatment, like group therapy, along with your GLP-1 agonist.
And if you notice any new symptoms related to your brain (or any other body part), tell the doctor who prescribed your medication.
Do GLP-1s Give You Brain Fog?
MAYBE YOU’VE NOTICED that some Reddit users say Ozempic causes brain fog and fatigue. While “brain fog” isn’t a medical term, a recent study in Frontiers in Pharmacology found that malaise—a general unwell feeling—and fatigue rank among the top 13 complaints about semaglutide on the FDA’s Adverse Event Reporting System database. Fatigue was the fourth most common symptom shared on patient forums.
Fatigue often accompanies weight loss, says Gary A. Sforzo, Ph.D., FACSM, professor emeritus, School of Health Sciences and Human Performance at Ithaca College. The reasons aren’t totally clear, but one explanation could be that as you take in fewer calories and reduce your blood sugar, your energy levels might dip, too. After all, blood sugar is a critical fuel source for your brain and body. As a result, you might feel fatigue, followed by some brain fog.
When you take these medications, you will eat less than usual, but don’t skimp on water. “Dehydration will compound these problems, so staying well hydrated may mitigate the problems,” he says.
