Brain insulin resistance linked to Alzheimer's, diabetes

Alzheimer's disease impairs insulin signalling in the brain, making a person with the most common form of dementia more likely to develop diabetes, suggests a new research conducted in mice.

The findings showed that mice with Alzheimer's have insulin resistance, which is a precursor to type II diabetes, in the hypothalamus the area of the brain that regulates metabolism of nutrients such as fatty acids, glucose, and amino acids in tissues including muscle, liver, and fat.

Also, the mice showed elevated levels of a particular group of amino acids in the blood, which acted as a biomarker of impaired brain insulin signalling.

"This is the first study to suggest that Alzheimer's disease pathology increases susceptibility to diabetes due to impaired insulin signalling in the hypothalamus," said lead author Christoph Buettner, associate professor at Icahn School of Medicine at Mount Sinai in New York, US.

Further, the study, published in the journal Alzheimer's and Dementia, provides a rationale that therapies developed to improve insulin signalling in the brain may reduce the likelihood that a patient with Alzheimer's disease develops diabetes, the researchers stated.

"Our findings represent a turning point in the understanding of the relationship between Alzheimer's disease, type II diabetes and insulin resistance," said co-author Sam Gandy, professor at Icahn School of Medicine at Mount Sinai.

In addition, ageing also is known to be one of the top risk factors for both diseases, and several previous epidemiological studies have supported the hypothesis that diabetes increases a person's risk for Alzheimer's disease.