Research shows that diabetes medications could reduce the risk of dementia. This could link the two diseases

A recently published Korean study suggests that people with type 2 diabetes who are prescribed a certain class of medication may have a significantly lower risk of dementia.

The researchers compared the health outcomes of more than 110,000 people aged 40 to 69 with type 2 diabetes who were prescribed a drug called SGLT-2 inhibitors with those of another 110,000 patients who took a different class of drugs, DPP-4 inhibitors, and followed the participants for an average of 670 days.

The researchers found that those who took an SGLT-2 inhibitor were 35 percent less likely to develop dementia after adjusting for potential confounding factors.

Diabetes is considered a risk factor for dementia, so it's not entirely surprising that treating diabetes can reduce the risk of dementia. But why would one drug reduce the risk more than another? And how are diabetes and dementia connected anyway?

Diabetes and dementia

Insulin is a hormone produced by the pancreas. Its job is to transport glucose (sugar) from our bloodstream into our cells, where it serves as an energy source. Type 2 diabetes occurs when our pancreas doesn't produce enough insulin or our cells develop a resistance to insulin.

Dementia is caused by changes in the brain and includes a variety of conditions that affect memory, thinking, mood, and our ability to perform everyday tasks.

Diabetes has long been considered a risk factor for the two most common forms of dementia, Alzheimer's disease and vascular dementia. Both forms are characterized by cognitive decline caused by disease of the blood vessels in the brain.

We don't understand exactly why diabetes and dementia are linked in this way, but there are some possible reasons.

Diabetes, for example, increases the risk of heart disease and strokes, which damage the heart and blood vessels. When blood vessels in the brain are damaged, this can contribute to cognitive decline.

In addition, high blood sugar levels lead to inflammation, which can damage brain cells and contribute to the development of dementia.

Treating diabetes could reduce the increased risk

Better control of blood sugar levels in diabetes helps protect blood vessels and reduces inflammation in the brain.

Diabetes can initially be controlled through lifestyle changes, such as diet and exercise, but treatment may also include medications such as those taken by participants in the Korean study.

Blood sugar control was comparable in patients taking both types of medication. But why did one medication reduce the risk of dementia compared to the other?

SGLT-2 inhibitors (which stands for sodium-glucose transport protein 2) lower blood sugar by promoting its breakdown by the kidneys. These drugs have also been shown to have positive effects on other areas of health, such as improving blood pressure, promoting weight loss, and reducing inflammation and oxidative stress (a type of cell damage).

Obesity and high blood pressure are themselves risk factors for vascular dementia and Alzheimer's dementia. It is therefore quite possible that these effects of SGLT-2 inhibitors reduce the risk of dementia more than would be expected from better blood sugar control alone.

Prevention versus treatment

It is important to stress that the benefit of a drug in reducing the risk of a disease is completely independent of the belief that the drug might be useful in treating that disease. For example, the best way to reduce your risk of lung cancer is to stop smoking. However, if you have lung cancer, quitting smoking is not enough to treat it.

Because of the evidence of a link between diabetes and dementia, certain diabetes medications have been studied as treatments for Alzheimer's disease, and they have been shown to improve cognitive abilities to some extent.

Semaglutide, better known by its trade name Ozempic, belongs to another class of diabetes medications (called GLP1 receptor agonists). Semaglutide is currently being studied as a treatment for early Alzheimer's disease in two clinical trials involving more than 3,500 patients.

The reason for these studies was observations made during clinical trials of semaglutide in diabetics. These showed that patients who took the drug were less likely to develop dementia than those who received a placebo.

Similar to SGLT-2 drugs, the GLP-1 class of drugs is known to reduce inflammation in the brain. GLP-1 drugs also appear to reduce chemical reactions that lead to an abnormal form of a protein called tau, one of the pathological hallmarks of Alzheimer's disease.

What happens next?

As our knowledge of the mechanisms underlying Alzheimer's disease and other forms of dementia continues to grow, advances in treatment will also continue to advance.

It is unlikely that a single drug will be the answer to Alzheimer's disease. Cancer treatment has now advanced to the point where the use of “drug cocktails,” or combinations of drugs, is now routine.

One possible future for these diabetes drugs is that they will be used as part of a range of treatments to combat the devastating effects of dementia or even help prevent it, even in people without diabetes. But before we get to that point, we need to do more research.

This article is republished from The Conversation under a Creative Commons license. Read the original article.