Common diabetes drug linked to lower dementia rates
New Australian research has found older diabetic patients using a drug called metformin experience slower rates of cognitive decline and dementia compared to those not using the medication. The findings build on the growing body of evidence suggesting this common drug generates compelling anti-aging effects.
Metformin is one of the most commonly prescribed drugs in the United States. It’s primarily used to manage blood sugar levels in patients with type 2 diabetes, however, over the past few years researchers have begun to investigate the drug’s surprising geroprotective qualities.
A geroprotective agent is anything that can be shown to extend the lifespan of an organism. Across several animal studies metformin has been found to confer lifespan-extending effects, and one compelling study last year even homed into on exactly how the drug may be modulating its anti-aging outcomes.
Understanding the broader systemic effects of metformin in humans has been a little more difficult. While the drug has been administered safely to tens of millions of diabetics for decades, it is challenging to separate the effects of the drug on the disease from its other potential benefits.
A robust 2017 meta-analysis crunched a massive volume of data attempting to separate metformin’s effect on improving diabetes from its potential healthspan-, or lifespan-, extending qualities. That study boldly concluded diabetics taking metformin displayed lower all-cause mortality rates and reduced incidences of cancer, compared to age-matched non-diabetic populations.
Looking at the effect of metformin on brain health, the research has been frustratingly inconsistent. Some studies suggest the drug may slow cognitive decline, while others found those taking metformin may actually experience higher rates of dementia. Confounding all this data is the simple fact that diabetics suffer a significantly higher risk of developing dementia compared to non-diabetics.
A new research study has looked a data from a project called the Sydney Memory and Ageing Study. This ongoing observational study started in 2005 and is following over 1,000 adults aged between 70 and 90 years. The general goal of the longitudinal research is to investigate the effects of aging on cognition. None of the cohort presented with signs of dementia at the beginning of the study.
Out of the 1,037 subjects, 123 had diabetes, of which around half were taking metformin. Across an average follow-up period of six years, the study found those diabetics taking metformin showed significantly slower rates of cognitive decline compared to those diabetic subjects not taking it. Even more interestingly, the study saw no difference in the rate of cognitive decline between those diabetics taking metformin and non-diabetic subjects.
"We've revealed the promising new potential for a safe and widely used medication, which could be life-changing for patients at risk of dementia and their families,” says first author on the study, Katherine Samaras. “For those with type 2 diabetes, metformin may add something extra to standard glucose lowering in diabetes care: a benefit for cognitive health.”
Of course a big question remains – how is metformin potentially slowing cognitive decline? Are these beneficial brain effects simply due to the drug improving diabetic symptoms? Or could these cognitive benefits be generated in healthy, non-diabetic cohorts as well?
"While an observational study does not provide conclusive 'proof' that metformin is protective against dementia, it does encourage us to study this and other anti-diabetic treatments for dementia prevention,” says senior author Perminder Sachdev. “Metformin has even been suggested to be anti-aging. The intriguing question is whether metformin is helpful in people with normal glucose metabolism. More work is clearly needed."
And that work is certainly underway. The Australian researchers are currently planning a large, randomized control trial to assess the effect of metformin on non-diabetic subjects at risk of dementia. Another similar study is also being planned in Europe, spanning several countries and recruiting 600 subjects to explore whether metformin can delay the onset of Alzheimer’s disease.
The new study was published in the journal Diabetes Care.
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If it has minimal side effects, this appears to be a very interesting result. Of course association is not necessarily causation.