This may be surprising as not too long ago, we reported on a different study which found the opposite–that using metformin might lower the risk for dementia in older men.
The study from Taiwanese researchers was presented on March 29, 2017 at The 13th International Conference on Alzheimer’s and Parkinson’s Diseases in Vienna Austria by Dr. Yi-Chun Kuan from the Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan.
The researchers found that long-term use of metformin may raise the risk of neurodegenerative disease in those with type 2 diabetes.
How Harmful Might Metformin Be to the Brain?
As reported by Medscape Medical News, Yi-Chun Kuan and team conducted a cohort study to follow a total 9,300 patients with type 2 diabetes in Taiwan for up to 12 years. They checked records for these patients from the National Health research database of Taiwan including 4,651 who had metformin prescriptions and 4651 matched controls who didn’t take any metformin.
Dr. Kuan told Medscape they adjusted for age, sex, and diabetes severity and that despite this, “the cumulative incidences of Parkinson’s and dementia were significantly higher for our metformin cohort” at 12 years.
In fact, the risk for Parkinson’s disease or Alzheimer’s dementia went up over 50 percent during a 12 year period in those who took metformin when compared to those who did not. Researchers also found that “outcome risks increased progressively with higher dosage and longer duration of treatment.”
Dr. Yi-Chun Kuan said, “We’d heard about a possible protective effect from metformin. However, we found the reverse,” and she added that large-scale, prospective studies would need to be done in other countries to get clarification of the results.
Another detail the researchers noted was that outcomes increased the longer a patient was on metformin and the higher the metformin dose they took, “especially with use for more than 300 days and doses greater than 240 g.”
A limitation of the study was that the patients on metformin might also be taking other diabetes drugs like insulin or sulfonylureas and Dr. Kuan said that she and her team would like to follow up on these other possible associations.
There was also no word on what the patient’s HbA1c levels were to help indicate the state of diabetes management nor an explanation on how factors were controlled for, as medical consultant, Dr. Larry Ereshefsky told Medscape.
Could a B12 Deficiency Have Anything to Do With It?
Recently, metformin has been shown to possibly cause B12 deficiency, particularly in those who take it longterm. One of the side effects of a B12 deficiency is neuropathy, or nerve damage.
A serious B12 deficiency has been known to also cause side effects like cognitive difficulties such as memory loss.
While this study still needs a follow-up, if you are concerned about metformin or your B12 levels, talk to your health care provider who can provide testing and if needed, guidance on how to get your B12 levels up.