Alzheimer’s Disease: Diabetes of the Third Kind?
Insulin may have some extremely important roles in the mind as well as the body.
Though best known for its role in promoting glucose uptake into cells, insulin has at least five hundred known functions in the human body. For many years nobody was sure whether insulin was important to the brain: neurons in the brain are unusual in that they do not need insulin to enter them. But then we discovered that insulin acts on other important metabolic processes in neurons. In the brain it also does duty as a chemical messenger and as a growth factor, and brain insulin signaling is crucial for the creation of memory. Over the years a number of theorists have suggested that some neurological and psychiatric illnesses could be a result of disturbances in insulin-related processes in the brain.
It is now beginning to look as if they may have been correct.
Some recent evidence has suggested that Alzheimer’s disease and diabetes mellitus share a number of common pathways and Alzheimer’s disease is associated with peripheral insulin resistance.
New research has been published by investigators from Northwestern University in the FASEB Journal – the journal of the Federation of American Societies for Experimental Biology – that may finally nail down the reason why insulin signaling may stop working in Alzheimer’s disease.
The research team used mature cultures of neurons from the hippocampus of the brain to study synapses – the connection between neurons – that have been implicated in learning and memory mechanisms. They wanted to examine the effect of a toxic protein, known to attack memory-forming synapses, that is called “ADDL” for “amyloid ß-derived diffusible ligand.” ADDLS are small, soluble aggregated proteins that accumulate in the earliest stages of Alzheimer’s disease. The researchers had previously found that ADDLs bind very specifically at synapses, which in turn initiates deterioration of their function, shape and composition. They now went on and studied the synapses and their insulin receptors before and after ADDLs were introduced. Regions of the nerve with normal numbers of insulin receptors have no ADDL binding, but when the ADDLs are added they remove insulin receptors from nerve cells, effectively making them insulin resistant.
And an insulin resistant neuron cannot participate in the formation of memories.
This finding implies that there is a fundamental connection between diabetes and Alzheimer’s disease, and this may in turn help us to see whether existing diabetes treatments might protect neurons from ADDLs and improve insulin signaling in people with Alzheimer’s disease.
The first type of diabetes is Type 1, a.k.a. insulin-dependent or juvenile onset. The second is Type 2, a.k.a. non-insulin-dependent diabetes. So is Alzheimer’s Type 3?
It has also been known for some time that physical exercise is one of the factors that may help reduce the chance of developing Alzheimer’s disease, and we may now have a mechanism by which it can help.
This is an extraordinarily interesting and important discovery that should lead to a whole new research angle, perhaps with medicines that are already available.
Dr. Richard G. Petty, MD is a world-renowned authority on the brain, and his revolutionary work on human energy systems has been acclaimed around the globe.
He is also an accredited specialist in internal and metabolic medicine, endocrinology, psychiatry, acupuncture and homeopathy. He has been an innovator and leader of the human potential movement for over thirty years and is also an active researcher, teacher, writer, professional speaker and broadcaster. He is the author of five books, including the groundbreaking and best selling CD series Healing, Meaning and Purpose. He has taught in over 45 countries and 48 states in the last ten years, but spends as much time as possible on his horse farm in Georgia.
