Drop in body temperature linked to aging aggravates manifestations of Alzheimer's disease

http://www.eurekalert.org/pub_releases/2016-04/ul-dib040716.php

Public Release: 7-Apr-2016
Drop in body temperature linked to aging aggravates manifestations of Alzheimer's disease
Université Laval

The drop in body temperature associated with aging could aggravate the main manifestations of Alzheimer's, suggests a study published in the latest issue of Neurobiology of Aging by Université Laval researchers. Although the phenomenon was demonstrated using transgenic mice, researchers believe that the findings are convincing enough to warrant further investigation in humans.

"We know that the incidence of Alzheimer's is low before age 65, but doubles every 5 to 6 years afterward," explains the study's lead author Frédéric Calon, professor at the Université Laval Faculty of Pharmacy and researcher at Centre de recherche du CHU de Québec-Université Laval. "We also know that metabolism and body temperature decrease as people get older. We therefore tested the hypothesis that the changes in the body's thermoregulation that occur with age amplify the main manifestations of Alzheimer's and that a vicious circle can even set in because the disease expresses itself in certain areas of the brain involved in temperature regulation."

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By comparing these transgenic mice with normal ones, researchers first established that the transgenic mice were less able to effectively maintain their body temperature as they aged. The difference reached almost 1° Celsius [1.8 F] by the age of 12 months. The researchers also observed that the manifestations of Alzheimer's were markedly more pronounced in transgenic mice when they were exposed to low temperatures: "The abnormal tau proteins responsible for neuron deterioration increase more in transgenic mice than normal mice, and the loss of synaptic proteins is more pronounced," explains Professor Calon.

Conversely, researchers observed that exposure to a high ambient temperature mitigated some manifestations of Alzheimer's disease. After one week in a 28°C environment, the transgenic mice's body temperature had increased by 1°C [82 F], beta-amyloid production had dropped substantially, and memory test results were comparable to those of normal mice.

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