People with Alzheimer’s disease have distinctive lesions within their brains. Individuals with diabetes also have pathological changes resembling those seen in patients with Alzheimer’s disease. People with this type of dementia appear to have impaired brain insulin metabolism. Could drugs for diabetes help ward off Alzheimer’s disease? Can metformin help delay dementia?
Using Drugs for Diabetes Against Dementia:
Studies of human brain tissue after death offer interesting insight on gene expression related to Alzheimer’s disease (PLOS One, Nov. 1, 2018). Treatment with diabetes medicines like insulin and metformin mute these changes. People who took such medicines before they died seem to have fewer pathological changes in gene expression. Such alterations are normally seen with this kind of dementia.
More than a decade ago, we interviewed Dr. Allen Roses, then VP of Genetics at GlaxoSmithKline. At that time, Dr. Roses was excited about the possibility that a compound similar to pioglitazone or other drugs for diabetes would prove helpful in delaying the onset of Alzheimer’s disease. Unfortunately, he died before that research could bear fruit.
The current research suggests that he may have been looking in a promising direction, however. Drugs for diabetes may not only be beneficial for people with type 2 diabetes, but might also help those susceptible to Alzheimer’s disease.
Epidemiology Suggests That Metformin Might Delay Dementia:
Several years ago, researchers reported at the annual conference of the Alzheimer’s Association (AAIC, July 15, 2013) that they had found a link between treatment with metformin and a reduced risk of dementia.
The investigators tracked nearly 15,000 patients with type 2 diabetes who started treatment between 1999 and 2001. The subjects had taken one of four possible drug types: metformin, sulfonylureas, thiazolidinediones (including pioglitazone) or insulin.
Normally, type 2 diabetes itself increases the risk for dementia. But five years after starting on metformin, patients had reduced their likelihood of developing cognitive decline by at least 20% compared to patients taking other diabetes drugs.
In contrast, the other medications, including insulin, were linked to an increased risk of dementia compared to metformin. This epidemiologic study has led more research to assess the true benefit of metformin against dementia.
Australian Research: Metformin vs. Dementia:
A study published in Diabetes Care (Sept. 23, 2020) adds more weight to the metformin message:
“OBJECTIVE: Type 2 diabetes (diabetes) is characterized by accelerated cognitive decline and higher dementia risk. Controversy exists regarding the impact of metformin, which is associated with both increased and decreased dementia rates. The objective of this study was to determine the association of metformin use with incident dementia and cognitive decline over 6 years in participants with diabetes compared with those not receiving metformin and those without diabetes.”
“CONCLUSIONS: Older people with diabetes receiving metformin have slower cognitive decline and lower dementia risk. Large randomized studies in people with and without diabetes will determine whether these associations can be attributed to metformin.”
You can learn more about controlling type 2 diabetes in our Guide to Managing Diabetes.