Screening bottles

Higher levels of insulin resistance are associated with speaking difficulties in women, a new study from Finland suggests.

Researchers from the University of Turku and Turku University Hospital measured insulin resistance in 5,935 adults (3.262 women) aged between 30 and 97. They then tested the participants’ verbal fluency by asking them to name as many animals as possible in 60 seconds.

Insulin resistance is a key risk factor in type 2 diabetes, and it is also associated with cognitive decline. Among the symptoms of insulin resistance include difficulty concentrating and lethargy.

The research teams evaluated the apolopoprotein E4 allele (APOE-4) during the study, which is a well-known risk factor for Alzheimer’s disease, the most common form of dementia.

Insulin resistance was observed in APOE-4 negative individuals, but not APOE-4 carriers, while higher insulin resistance was linked with decreased verbal fluency in women, but not men.

The researchers hypothesised that this gender difference could be due to white matter hyperintensities, which are lesions in the brain. These can be detected by brain imaging, and are reported to be more common in women than men.

However, they stressed that as the study was cross-sectional, the causal effects of insulin resistance on cognitive function could not be evaluated. Rather, insulin resistance could be a risk factor for cognitive decline in women.

“Although verbal fluency is not the most sensitive measure to identify early cognitive decline in adults, it associates well with insulin resistance for women and the brain regions that are negatively influenced by insulin resistance,” said the authors.

“The association between insulin resistance and cognitive functions could indicate that insulin resistance is a risk factor for Alzheimer’s disease.”

The findings of this study appear in the journal Diabetologia.