Researchers have provided initial and somewhat speculative data to suggest that the decrease in body temperature that occurs in old age may speed the progression of mechanisms implicated in Alzheimer's disease:
"We know that the incidence of Alzheimer's is low before age 65, but doubles every 5 to 6 years afterward. 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." The researchers used a type of transgenic mice that express the main manifestations of Alzheimer's disease as they age: They produce beta-amyloid, which leads to the formation of senile plaque in the brain; they are affected by a pathology that renders neurons non-functional; and they lose synaptic proteins. In these mice, memory problems begin to arise at the age of 6 months.
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 by the age of 12 months. The researchers also observed that 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. 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, beta-amyloid production had dropped substantially, and memory test results were comparable to those of normal mice. "Our findings suggest that it is worth exploring the treatment of thermoregulation among seniors suffering from Alzheimer's."