A recently published Korean study shows that people with type 2 diabetes who are prescribed a certain class of drugs may be at a significantly lower risk of dementia, Science Alert reported.
Researchers compared the health outcomes of more than 110,000 people aged 40 to 69 with type 2 diabetes who were prescribed drugs called SGLT-2 inhibitors with those of another 110,000 patients taking another class of drugs, DPP inhibitors -4. Participants were observed for an average of 670 days.
They found that after accounting for potential confounders, those taking an SGLT-2 inhibitor were 35% less likely to develop dementia.
Diabetes is recognized as a risk factor for dementia. So it's not entirely surprising that its treatment can reduce the risk of dementia. But why does one drug reduce risk more than another? And how are diabetes and dementia even related?
Insulin is a hormone produced by the pancreas. Its job is to move glucose (sugar) from the blood to the cells, where it serves as a source of energy. Type 2 diabetes occurs when the pancreas does not produce enough insulin or our cells develop resistance to insulin.
Dementia is caused by changes in the brain and encompasses several conditions that affect memory, thinking, mood and our ability to perform everyday tasks.
Diabetes has long been recognized as a risk factor for Alzheimer's disease and vascular dementia, the two most common forms of dementia. Both are characterized by cognitive decline caused by disease of the blood vessels in the brain.
We don't fully understand why diabetes and dementia are linked in this way, but there are several possible reasons.
For example, diabetes increases the risk of heart disease and stroke, which damage the heart and blood vessels. When the blood vessels in the brain are damaged, it can contribute to cognitive decline.
Also, high blood sugar levels cause inflammation, which can damage brain cells and contribute to the development of dementia.
Better control of blood sugar levels in diabetes helps protect blood vessels and reduces inflammation in the brain.
Diabetes can be controlled initially with lifestyle changes such as diet and exercise, but treatment can also include medications like those taken by the patients in the Korean study.
Patients taking either drug had comparable blood glucose control. But why does one reduce people's risk of developing dementia and the other not?
An SGLT-2 (which stands for sodium-glucose transport protein 2) inhibitor lowers blood glucose by increasing its removal by the kidneys.
These drugs are known to have positive effects on other areas of health, including improving blood pressure, promoting weight loss, and reducing inflammation and oxidative stress (a type of damage to our cells).
Obesity and high blood pressure are themselves risk factors for Alzheimer's disease and vascular dementia, so it may be that these effects of SGLT-2 inhibitors reduce the risk of dementia to a greater extent than would be expected on its own from better blood glucose control.
It is important to emphasize that the benefit of reducing the risk of developing a disease is different from the assumption that a drug may be useful in its treatment.
The best way to reduce the risk of lung cancer is to stop smoking. Once you already have the disease, however, quitting smoking is not enough to treat it.
Some diabetes drugs have already been studied as treatments for Alzheimer's disease. Studies show that they provide some benefit to cognition.
Semaglutide, better known by the trade name Ozempic, is a member of 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 research itself was prompted by observations during clinical trials of semaglutide in people with diabetes, which showed a lower incidence of dementia in those taking the drug compared to those taking a placebo.
Like SGLT-2 drugs, the GLP1 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 hallmarks of Alzheimer's disease.
As our knowledge of the mechanisms underlying Alzheimer's disease and other forms of dementia continues to grow, so do advances in treatment.
A single drug is unlikely to be the answer to Alzheimer's disease. Cancer treatment has evolved to the point where the use of "drug cocktails" or a combination of drugs is routine practice.
It is possible that in the future these diabetes drugs will be used as part of a range of treatments to combat devastating dementia or to prevent dementia even in people without diabetes. But more research is needed before we get to that point. | BGNES
