Low-Cost Pill Linked to Lower Dementia Risk, Study Finds

The Potential of Metformin in Dementia Prevention

Doctors are increasingly focusing on ways to prevent dementia, and one promising candidate could be a drug that has been used for decades in the treatment of diabetes. Before the rise of medications like Ozempic, metformin was already a key player in managing type 2 diabetes. This medication, which has been in use for over 100 years, works by reducing the amount of sugar produced by the liver and improving the body's response to insulin. It is the first-line treatment for more than 70% of people newly diagnosed with type 2 diabetes.

For many years, doctors have speculated that metformin might also have protective effects against dementia. However, the evidence has been mixed, with some studies suggesting it may worsen the development of Alzheimer’s disease, while others indicate it could offer brain protection. Recently, researchers from Taipei Medical University in Taiwan have added their voice to the growing body of evidence supporting metformin’s potential as a dementia preventative.

Their study focused on half a million overweight and obese individuals without diabetes and found that those who took metformin had a lower risk of developing dementia or dying from any cause, regardless of their BMI. Obesity is known to be a risk factor for dementia, as it weakens the body's defenses against brain damage and can lead to chronic inflammation, which may harm nerve cells.

Most previous research into metformin’s role in dementia prevention has centered on people with diabetes. The latest study from Taiwanese researchers is the first to examine its effects in individuals with obesity using real-world data. The researchers used an electronic health records database covering millions of patients from 66 U.S. healthcare systems, including hospitals, specialty centers, and clinics. They noted that the data reflects a diverse population, making the findings widely applicable.

The study included about 905,000 people, evenly split into two groups: those taking metformin and those not. Participants were matched for age, health, and other factors to ensure a fair comparison. The metformin group had been prescribed the drug at least twice in their lives for at least six months.

While the study did not specify why individuals were prescribed metformin, it is used for more than just diabetes. It can also treat prediabetes, metabolic disorders contributing to obesity, and conditions like polycystic ovary syndrome.

Researchers categorized participants into four groups based on BMI: overweight (25–29.9), obese class I (30–34.9), obese class II (35–39.9), and morbidly obese (over 40). After following patients for 10 years, those who took metformin showed a reduced risk of dementia across all BMI groups.

The risk reduction varied slightly depending on weight. Those with a BMI of 30 to 34.9 had an 8% lower dementia risk, while those with a BMI of 25 to 29.9 saw a 12.5% reduction. People with a BMI of 35 to 39.9 had a 4% lower risk, which researchers considered statistically insignificant due to a smaller sample size. No significant difference was observed in those with a BMI over 40.

When looking at death from any cause, metformin users also had a significantly lower risk across all BMI categories. The effect on death risk was stronger than on dementia risk. For example, those with a BMI between 25 and 29.9 had a 28% lower risk of death, while those with a BMI of 30 to 34.9 had a 27% lower risk.

The findings from the Taipei team were published in the journal Diabetes, Obesity and Metabolism. Scientists believe metformin’s impact on cognitive health may stem from its unique properties and the condition it treats. A 2013 review found that people with diabetes are 73% more likely to develop dementia and 56% more likely to develop Alzheimer’s.

In 2020, Australian researchers followed over 1,000 dementia-free seniors aged 70 to 90 in Sydney for up to six years. They tested memory and thinking skills at two and six years. The study compared three groups: people with type 2 diabetes on metformin, those with diabetes not on the drug, and those without diabetes. Results showed that metformin users had an 81% lower risk of dementia compared to those with diabetes not on the drug. Additionally, brain scans and cognitive tests indicated that metformin users experienced a slower decline in cognitive abilities.