1105 GMT March 22, 2019
The association was not seen in men, although the researchers could not determine exactly why that was so.
In the study, Finnish researchers measured what is called low verbal fluency, which is the rate at which you produce words, scicasts.com said.
"Preclinical Alzheimer's disease typically starts with episodic memory decline. However, verbal fluency is a measure of executive function, and also deficits in executive function can be found early in the disease," said study author Dr. Laura Ekblad, a researcher at the University of Turku. Executive function includes higher-order processes such as working memory, planning and problem solving.
"Not all individuals with insulin resistance will develop cognitive thinking and memory impairment or dementia later in life," she added.
Still, another expert noted that increasing evidence is linking insulin resistance and type 2 diabetes to memory troubles.
And the relationship between gender and Alzheimer's disease has been a very hot topic in research lately, said Keith Fargo, director of scientific programs and outreach at the Alzheimer's Association.
"The majority of people with Alzheimer's disease are women. Women are about twice as likely to get Alzheimer's disease. What we don't know for sure is why," Fargo said.
The current study included almost 6,000 people in Finland. Their ages ranged from 30 to 97, with a mean age of 52.5 years. The researchers tested brain health using a variety of tests, including verbal fluency. To test verbal fluency, the study volunteers were asked to name as many animals as they could in 60 seconds.
The investigators also looked at whether or not people had insulin resistance, and if they had a gene that's linked to a higher risk of Alzheimer's disease called APOE-E4.
Insulin is a hormone that helps cells use sugar from foods as fuel. When someone develops insulin resistance, they still produce enough insulin, but it doesn't work as effectively.
The researchers found that women with higher levels of insulin resistance were more likely to score poorly on the verbal fluency test.