New study: GLP-1 weight loss drugs may cut dementia risk by 45%

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New evidence suggests GLP-1 weight loss drugs may cut dementia risk. Get the full story in our explainer.

For medical researchers, GLP-1 weight loss drugs must seem like the golden goose that never stops laying.

Wegovy (semaglutide) and Mounjaro (tirzepatide), for instance, were first launched as treatments for type 2 diabetes. Then, following a raft of groundbreaking clinical studies, they were rolled out as weight loss medications.

But then the benefits kept coming. Wegovy was found to reduce the risk of death from heart attack and stroke by 20% among people living with heart disease and obesity.¹ And compelling evidence emerged to suggest that semaglutide may help curb addictive behaviours like drinking and smoking.

Now, a new study points to yet another potential benefit. According to researchers from the University of Galway in Ireland, GLP-1 drugs may cut the risk of dementia by almost half.

If this sounds too good to be true, well… There are a couple of caveats to keep in mind.

What you need to know about the dementia study

1. We don't know whether the findings apply to everyone

The first point of caution is that the study only looked at the effects of GLP-1s on people living with type 2 diabetes.

Researchers found that the odds of developing dementia were 45% lower among GLP-1 patients with diabetes compared to those taking a placebo (dummy drug). However, it's known that type 2 diabetes is a risk factor for dementia. It may be that by treating the diabetes, we are also treating the complications that can lead to dementia.

No doubt – this is a good thing. However, it raises a question: can we expect GLP-1s to have the same effect on patients without diabetes?

2. We need more targeted research

The second caveat points to both a strength and a weakness of the study. See, the dementia study falls under a category of research known as 'meta-analyses'.

A meta-analysis is a study of studies. With meta-analyses, researchers don't conduct new experiments of their own. Instead, they take a bunch of related studies, gather up all their data and draw fresh conclusions from those data.

In the case of the dementia study, the team gathered data from 26 clinical trials examining the effects of glucose-lowering therapies on patients with diabetes. In total, they looked at data relating to 160,191 patients.

Picture of a scientist/researcher using a computer.

This approach was partly born out of necessity.

See, it's hard to test whether drugs affect dementia risk. That's because patients must undergo a lengthy evaluation before doctors can diagnose the disease. But an outcome like weight loss is easy to test for. You can, more or less, simply ask the patient to stand on a scale and record the result.

However, if a researcher is studying weight loss, say, and a patient happens to develop dementia, the researcher will still record the diagnosis. That's where a meta-analysis can help make things clearer. One or two dementia diagnoses during a study don't tell us much. But if we gather these data points from multiple studies and look at them together, a picture starts to emerge.

Meta-analyses are great for revealing clues like this. Without this new study, we may never have noticed a link between GLP-1s and dementia risk.

But to truly understand the whats, hows and whys, we need more targeted research. Ideally, this research would make dementia risk the main focus – and look exclusively at the effects of GLP-1s versus placebo.

Final thoughts

Despite these caveats, the new findings are compelling – not least because they point to a possible new treatment pathway for people at risk of dementia.

They also inch us closer to understanding the full effects of GLP-1 medications on the body. By drawing links between GLP-1s and dementia, they add weight to the argument that these drugs can benefit the brain as well as the gut.

The evidence is mounting. When researchers found that semaglutide may help curb alcohol cravings, experts suggested it was because the drug dampens the 'reward centres' of the brain. And scientists looked to similar conclusions when, mere weeks ago, a new study emerged looking at genetic causes of obesity in dogs and humans.

It's an exciting area of research – and we don't doubt that more evidence will come to light soon. When it does, we'll be sure to keep you posted.

SemaPen is an online weight loss injection clinic and part of the Phoenix Health Group. Follow our blog for more news about GLP-1 injections and weight loss treatments.

Sources

1. Lincoff, A.M. et al. (2023) "Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes" The New England Journal of Medicine, 389(24) https://doi.org/10.1056/NEJMoa2307563

2. Hendershot, C.S. et al. (2025) "Once-Weekly Semaglutide in Adults With Alcohol Use Disorder: A Randomized Clinical Trial" JAMA Psychiatry https://doi.org/10.1001/jamapsychiatry.2024.4789

3. Seminer, A. et al. (2025) "Cardioprotective Glucose-Lowering Agents and Dementia Risk: A Systematic Review and Meta-Analysis" JAMA Neurology https://doi.org/10.1001/jamaneurol.2025.0360

This article was reviewed by and approved by Alice Fletcher, Lead Bariatric Dietitian, on 10 April 2025.

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