Insulin resistance resulting from obesity increases the risk of developing Alzheimer’s disease, according to US researchers.
A study, published in the Journal of the American Medical Association Neurology, found a strong association between insulin resistance and memory function decline.
Researchers examined brain scans in 150 late middle-aged adults, who were at risk for Alzheimer’s disease, but showed no sign of memory loss.
“People need to know that insulin resistance or related problems with metabolism can have an effect in the here and now on how they think”
The scans detected that people with higher levels of insulin resistance used less blood sugar in areas of the brain most susceptible to Alzheimer’s, meaning the brain had less energy to relay information and function.
The researchers focused on the medial temporal lobe, specifically the hippocampus – a critical region of the brain for learning and sending information to long-term memory. It is also one of the brain areas that first show massive atrophy or shrinkage due to Alzheimer’s disease.
Study author Dr Auriel Willette, a research scientist at Iowa State University, said: “If you don’t have as much fuel, you’re not going to be as adept at remembering something or doing something.”
“This is important with Alzheimer’s disease, because over the course of the disease there is a progressive decrease in the amount of blood sugar used in certain brain regions,” he said. “Those regions end up using less and less.”
It is the first study to look at insulin resistance in late middle-aged people – those with an average age was 60 – to identify a pattern of decreased blood sugar use related to Alzheimer’s and link that to memory decline, said Dr Willette.
He added that raising awareness of a link between insulin resistance and Alzheimer’s disease was important for prevention.
“People need to know that insulin resistance or related problems with metabolism can have an effect in the here and now on how they think, and it’s important to treat,” he said.
For Alzheimer’s, it’s not just people with type 2 diabetes,” he said. “Even people with mild or moderate insulin resistance who don’t have type 2 diabetes might have an increased risk for Alzheimer’s disease, because they’re showing many of the same sorts of brain and memory relationships.”
Study participants were recruited through the University of Wisconsin-Madison and Wisconsin Registry for Alzheimer’s Prevention study, an ongoing study that examines genetic, biological and lifestyle factors that contribute to dementia.