HEALTHeNEWS

Most of us know that our pancreas produces insulin but researchers have recently learned that our brains also produce insulin. They have also discovered that this brain insulin and its growth factors are necessary for the survival of brain cells. It appears that a deficiency of this newly appreciated brain insulin may actually contribute to the progression of Alzheimer’s Disease.

While it has been previously discovered that insulin resistance, a characteristic of diabetes, is associated with neurodegeneration, one study demonstrated strong evidence of the link between diabetes and Alzheimer’s disease.Additionally, through studying a genetic abnormality in rats that blocks insulin signals in the brain, scientists found insulin and IGF (insulin-like growth factor) I and II were expressed in neurons positioned in several locations in the brain. Researchers concluded that a decrease in insulin signaling in the brain contributes to the degeneration of brain cells–an early sign of Alzheimer’s disease. These irregularities, however, do not relate to type 1 or type 2 diabetes, but serve as indicators of a different, more complex, disease process that stems from the central nervous system. Postmortem ResearchBy looking at postmortem (collected after death) brain tissue in Alzheimer’s patients, researchers discovered that growth factors were not produced at normal levels in the part of the brain responsible for memory–known as the hippocampus–causing cells in other parts of the brain to die.Insulin and IGF I were greatly reduced in all the areas of the brain affected by the progression of Alzheimer’s. Such areas include the frontal cortex, hippocampus and hypothalamus. While scientists have suspected a link between diabetes and Alzheimer’s disease, this is the first study to provide evidence of that connection.Journal of Alzheimer’s Disease February 2005; 7(1): 45-61