The human brain naturally changes as we grow older. Starting in our 30s or 40s, the brain slowly becomes smaller, and some nerve cells lose their connections.
This is a normal part of aging. However, some people’s brains appear to age much faster than expected.
When this happens, the risk of memory loss, slower thinking, dementia, depression, stroke, and other brain disorders may increase.
Scientists have long wondered why some brains age more quickly than others. Lifestyle, genes, health conditions, and diet are all thought to play a role, but the full picture has remained unclear.
Now, a new study by researchers from Jilin University and China Medical University has identified an important clue. Their findings suggest that higher blood glucose levels may speed up the aging of the brain.
Glucose is a simple sugar that provides energy for the body’s cells. After eating, glucose enters the bloodstream and is moved into cells with the help of insulin.
Although the brain needs glucose to function, having too much glucose in the blood for long periods can damage blood vessels and tissues. High blood sugar is common in people with diabetes and prediabetes, but even people without diabetes can sometimes have elevated glucose levels.
The researchers analyzed information from the UK Biobank, one of the world’s largest health research databases. It contains brain scans, blood tests, genetic information, and health records from hundreds of thousands of volunteers. The team first studied MRI brain scans from more than 4,300 healthy adults.
Using over one thousand brain measurements, they trained artificial intelligence models to estimate the age of each person’s brain. The most accurate model, called LASSO regression, predicted brain age with an average error of only about 3.3 years.
The scientists then applied this model to more than 37,000 people. They calculated each person’s brain age gap, which compares brain age with actual age. A positive brain age gap means the brain appears older than expected.
Next, the researchers examined blood samples from more than 21,000 participants. They discovered nine blood molecules linked with brain aging, but glucose showed the strongest relationship. People with higher blood glucose tended to have brains that looked older on MRI scans.
The team also studied participants’ genes. Their analysis suggested that glucose itself may play a direct role in accelerating brain aging rather than simply being linked with it. Although more studies are needed, this strengthens the evidence that controlling blood sugar may help protect the brain.
Higher glucose levels were also linked with a greater risk of dementia, Alzheimer’s disease, vascular dementia, Parkinson’s disease, stroke, depression, and anxiety. People with higher glucose generally performed worse on tests of memory, thinking, movement, and mental well-being. Brain scans also showed smaller brain volumes in many different regions.
The findings do not prove that lowering blood sugar will stop brain aging, but they suggest glucose may be a modifiable risk factor. Healthy eating, regular physical activity, maintaining a healthy weight, and managing diabetes may all help keep blood glucose under better control.
The research was published in Molecular Psychiatry.
This is a strong study because it combined brain scans, blood tests, genetics, and artificial intelligence in tens of thousands of people. However, it cannot completely prove cause and effect, and future clinical studies are needed to determine whether lowering glucose slows brain aging.
Even so, the evidence suggests that keeping blood sugar in a healthy range may benefit not only the heart but also the brain throughout life.
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