Psychology and wellbeing - Alzheimer's Disease, A Third Form Of Diabetes?

Insulin may be as important for the mind as it is for the body. Research in the last few years has raised the possibility that Alzheimer's memory loss could be due to a novel third form of diabetes.

Now scientists at Northwestern University have discovered why brain insulin signaling, crucial for memory formation, would stop working in Alzheimer's disease. They have shown that a toxic protein found in the brains of individuals with Alzheimer's removes insulin receptors from nerve cells, rendering those neurons insulin resistant. (The protein, known to attack memory-forming synapses, is called an ADDL for "amyloid ß-derived diffusible ligand.")

With other research showing that levels of brain insulin and its related receptors are lower in individuals with Alzheimer's disease, the Northwestern study sheds light on the emerging idea of Alzheimer's being a "type 3" diabetes.

In the brain, insulin and insulin receptors are vital to learning and memory. When insulin binds to a receptor at a synapse, it turns on a mechanism necessary for nerve cells to survive and memories to form.

"We found the binding of ADDLs to synapses somehow prevents insulin receptors from accumulating at the synapses where they are needed," said William L. Klein, who led the research team.

The clinical data strongly support a theory in which ADDLs accumulate at the beginning of Alzheimer's disease and block memory function by a process predicted to be reversible.

"With proper research and development the drug arsenal for type 2 diabetes, in which individuals become insulin resistant, may be translated to Alzheimer's treatment," said Klein. "I think such drugs could supercede currently available Alzheimer's drugs."

This research is published in the FASEB Journal.

This story is adapted from Science Daily

Illustration:
A et B: neurons
4. Synapse
5. Réceptors
(Source: Wikipedia)

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