Chronic hyperglycemia in type 2 diabetes linked to alzheimer's disease: Study

Chronic hyperglycemia may alter working memory performance and change aspects of working memory networks.

USA: A team of neuroscientists from UNLV has confirmed the link between type 2 diabetes and Alzheimer's disease (AD) in a recent study published in the journal Communications Biology.

According to James M. Hyman, University of Nevada Las Vegas, Las Vegas, NV, USA, and colleagues, chronic hyperglycemia impairs working memory performance and alters fundamental aspects of working memory networks.

The study is in continuation with a six-year collaboration between Hyman and coauthor Jefferson Kinney for a better understanding of why diabetes increases Alzheimer's risk.

In the lieu of a rapid increase in the number of Alzheimer's disease diagnoses and the accelerated incidence of diabetes and pre-diabetes, it becomes crucial to understand the link between the two. Also, some previous studies have shown an association between diabetes mellitus, a metabolic disease associated with dysregulated glucose and insulin levels, and increased risk of AD later in life but the reason behind it is still not clear.

The researchers found that two parts of the brain that are central to forming and retrieving memories -; the hippocampus and the anterior cingulate cortex -; were over-connected, or hypersynchronized. When it came time to remember the correct information and complete a task, these two parts of the brain – which are affected early in Alzheimer's progression – were over-communicating with each other, sparking errors.

"We know synchrony is important for different parts of the brain to work together. But, we're finding more and more these days, that the key with neural synchrony is it has to happen at the right time, and it has to happen with control," Hyman said. "Sometimes, there's just too much 'talking' between certain areas and we think this leads to memory difficulties, among other things."

"It is possible that in Alzheimer's patients there's over-connection in certain areas where there should be flexibility. And in the models in our study, we're seeing evidence of that in real-time at these crucial moments to do the task." Hyman explained.

This most recent finding not only provides novel information about brain activity in the hyperglycemia model but also provides an additional important measure that can be used for continuing research.

"Our next step is to combine the biochemical markers and electrophysiology data to test specific mechanisms responsible and potential treatments," said Kinney. "This research will now be able to work towards understanding the risk as well as what may be able to be done to help."

Reference:

Wirt, R.A., Crew, L.A., Ortiz, A.A. et al. Altered theta rhythm and hippocampal-cortical interactions underlie working memory deficits in a hyperglycemia risk factor model of Alzheimer's disease. Commun Biol 4, 1036 (2021). https://doi.org/10.1038/s42003-021-02558-4