Research Shows Diabetes Rewires the Brain, Mimicking Early Alzheimer Disease

New findings from the University of Nevada, Las Vegas (UNLV), suggest that high blood sugar levels associated with type 2 diabetes rewire the brain, weakening key functions and mimicking symptoms of early Alzheimer disease.¹

Research has previously demonstrated that there are connections between blood sugar levels and brain function. For instance, a 2009 study demonstrated connections between excess glucose consumption and memory and cognitive deficiencies. Because the brain is the most energy-demanding organ, having the proper fuel for that energy is crucial.²

The brain is dependent on sugar for its main fuel | Image credit: Ekaterina | stock.adobe.com

“The brain is dependent on sugar for its main fuel,” explained Vera Novak, MD, PhD, an associate professor of medicine at Beth Israel Deaconess Medical Center and Harvard Medical School associate, in a news release. “It cannot be without it.”²

According to researchers at Harvard University, long-term diabetes has significant impacts on neurons in the brain. High blood glucose can affect functional connectivity, which links brain regions that share functional properties, and brain matter. This can cause the brain to atrophy and can lead to small-vessel disease, which restricts blood flow and causes cognitive difficulties. In severe cases, this can lead to the development of vascular dementia.²

Researchers at UNLV acknowledged this known connection, noting that patients with type 2 diabetes are more prone to psychiatric and neurodegenerative disorders, as well as a 65% higher risk of developing Alzheimer disease. However, the precise links between diabetes and neurodegenerative diseases are not well understood.³

Now, according to their study findings, the researchers say it appears that diabetes weakens the function of the anterior cingulate cortex (ACC), which suppresses reward perception and memory signals. This induces mild cognitive impairment, like that observed during the early stages of Alzheimer disease.¹

“Diabetes may be altering the brain similarly to early stages of Alzheimer disease,” said lead researcher and UNLV psychology professor James Hyman, PhD, in a news release. “Further research is needed, but these findings have the potential to help researchers unlock clues to improved diagnostic or treatment strategies for the disease.”³

To conduct their research, investigators observed brain activity and behavior in rodent models. They found that diabetic mice’s’ anticipation of a reward, such as a sweet treat, is heightened in comparison to healthy brains. Furthermore, after receiving the reward, subjects with healthy brains pause to savor it, whereas those with diabetes quickly move on to the next reward.¹

Hyperglycemic insulin levels seemed to impair the ACC’s information-processing ability surrounding rewards. This weakened reward signal was attributed to a dampened input into the ACC from the hippocampus, which is also crucial for Alzheimer disease and is involved in spatial and autobiographical memory.¹

“We think the hippocampus tells the subject where it is location-wise, and the ACC tells the subject what it is doing and that it’s getting a reward,” Hyman said in the news release. “These things should come together and make the subject remember it was just in a special, rewarding location, but this doesn’t happen with the ones that have type 2 diabetes.”³

These findings could be significant given the global prevalence of diabetes, and particularly type 2 diabetes, which is associated with obesity and can lead to chronic damage to the nerves, blood vessels, and surrounding tissues and organs. The researchers also suggest that the hippocampus-to-ACC projection could be worth exploring as a treatment target for mood disorders, which the ACC is already known to be involved with.³

REFERENCES

1. Bhasin G, Flores E, Crew LA, et al. ACC reward location information is carried by hippocampal theta synchrony and suppressed in a type 2 diabetes model. J Neuro Sci. 2025;e1546242025. doi:10.1523/JNEUROSCI.1546-24.2025

2. Sugar and the Brain. Harvard Medical School. Spring 2016. Accessed April 24, 2025. https://hms.harvard.edu/news-events/publications-archive/brain/sugar-brain#:~:text=Long%2Dterm%20diabetes%E2%80%94either%20type,brain%20to%20atrophy%20or%20shrink.

3. Study Unlocks How Diabetes Distorts Memory and Reward Processing. News release. University of Nevada, Las Vegas. March 25, 2025. Accessed April 24, 2025. https://www.unlv.edu/news/release/study-unlocks-how-diabetes-distorts-memory-and-reward-processing