Another study finds metformin lowers dementia risk, but there's a catch

Another study has linked the popular drug used to treat type-2 diabetes, metformin, with a decreased risk of developing Alzheimer's disease later in life, but that may not mean what you think it does. Dementia, including Alzheimer's, is believed to be caused by a variety of genetics and lifestyle factors, with the latter having a massive influence — so much so that even those who have a genetic risk for the disease may stall its onset until very late in life by adopting the right habits.

Typically speaking, the lifestyle factors that may have the biggest impact on one's dementia risk include activity levels, diet, and how often one 'exercises' their mind. When it comes to diet, a number of issues have been linked to dementia risk, including excessively high blood sugarexcessively high insulin levels...two things found in people who suffer from type-2 diabetes.

It shouldn't be surprising, then, that metformin, a drug designed to help control blood sugar and insulin, has also been linked with lowered odds of diabetics developing dementia later in life. That's according to a new study recently published by the American Diabetes Association in its Diabetes Care journal.

Existing risks

The researchers found that older adults suffering from type-2 diabetes who were treated with metformin experience 'significantly' slower decline in their executive function and overall cognition compared to diabetics who didn't take metformin. In addition, the diabetics who didn't take the drug were also found to have 'significantly higher' rates of dementia in older ages than the metformin group.

The study involved around 1,000 adults who were 70 to 90 years old at the time of the study and who didn't have dementia at the start of the research (data was pulled from the Sydney Memory and Ageing Study). The participants' cognitive functioning was tested every two years for the duration of more than six years, with researchers focusing on those who had diabetes, but who didn't have any other 'progressive malignancy' or psychiatric/neurological issues.

The key point there, of course, is that the lowered dementia risk with metformin was observed in people who had a disease that naturally put them at much greater risk than the average person. It shouldn't be surprising that taking a drug to control the two big risk factors — high blood sugar and insulin levels — would reduce the risk of developing dementia, but can metformin also help those who aren't diabetic?

Promising results

Back in late 2017, a study from Lancaster University linked metformin with a significant reversal of memory loss in mice who were suffering from Alzheimer's disease. The researchers had found that metformin worked in multiple ways to protect the brain from decline, resulting in mice with dementia that experienced improvements in brain amyloid plaque levels, increased brain growth factor, reduced oxidative stress and inflammation, and decreased rates of nerve cell loss.

At the time, that study's lead researcher Professor Christian Holscher had said:

These very promising outcomes demonstrate the efficacy of these novel multiple receptor drugs that originally were developed to treat type 2 diabetes but have shown consistent neuroprotective effects in several studies ... Clinical studies with an older version of this drug type already showed very promising results in people with Alzheimer's disease or with mood disorders.