A hormone found in body fat could develop the risk of dementia and Alzheimer's disease in older women, a study found.

"It is well established that insulin signaling is dysfunctional in the brains of patients with AD, and since adiponectin enhances insulin sensitivity, one would also expect beneficial actions protecting against cognitive decline," the researchers from Tufts University write.

"Our data, however, indicate that elevated adiponectin level was associated with an increased risk of dementia and AD in women."

Thomas M. van Himbergen, Ph.D., from the Lipid Metabolism Laboratory, Human Nutrition Research Center on Aging, and colleagues measured levels of glucose, insulin, and glycated albumin, as well as C reactive protein, lipoprotein associated phospholipase A2, and adiponectin in the plasma of patients at the 19th biennial examination (1985 - 1988) of the Framingham Heart Study.

The 840 patients (541 women, median age of 76 years at the study's beginning) were followed-up for an average of 13 years and evaluated for signs of the development of AD and all-cause dementia.

During that time, 159 patients, about 19%, developed dementia, including 125 cases of AD.

After adjustment for other dementia risk factors (age, apoE genotype, low plasma docosahexaenoic acid, weight change) only adiponectin in women was associated with an increased risk of all-cause dementia and AD.

"One of the main features of adiponectin is that it has been shown to play a role in the sensitization of insulin and therefore may become a therapeutic target for the treatment of T2D (type 2 diabetes). Surprisingly, a higher adiponectin level was found to be a predictor of all-cause and vascular mortality.

"In concurrence with the mortality findings, the current investigation shows that an elevated adiponectin level is also an independent predictor for all-cause dementia and AD in women," the authors conclude.

Adiponectin is a protein hormone produced and secreted exclusively by adipocytes (fat cells) that regulates the metabolism of lipids and glucose. Adiponectin influences the body's response to insulin. Adiponectin also has antiinflammatory effects on the cells lining the walls of blood vessels.