Anyone reading this likely already knows at least a little bit (and maybe a lot) about D-chiro-inositol (DCI) and PCOS, and some of you may even be scratching your heads wondering what DCI or PCOS could possibly have to do with Alzheimer's Disease, a form of progressive dementia affecting an estimated 5.6 million Americans. Well, the answer is a very interesting one, so please read on, especially if you or anyone you know has a loved one struggling with Alzheimer's disease.
In recent years, researchers have built a mounting case that Alzheimer's disease is a specific form of insulin resistance some have even gone so far as to call Alzheimer's disease type III diabetes. This avenue of research grew from complementary observations from epidemiology and molecular biology. People with diabetes and insulin resistance are more likely to develop Alzheimer's disease, and the neurons in the central nervous system have some unique responses to insulin. Since then, the hypothesis of Alzheimer's disease as insulin resistance has evolved and gained experimental support.
This body of evidence lead one group of researchers to propose that D-chiro-inositol might be an effective therapy for Alzheimer's disease. They based their hypothesis on D-chiro-inositol's proven efficacy in three other health problems where insulin resistance is a primary feature: diabetes, PCOS, and preeclampsia. They also preferred to study DCI over other possible therapeutic agents because it is a nutritional supplement with a proven track record of safety, and because it appears to cross the blood-brain barrier (which is crucial for any Alzheimer's therapy to be effective).
These researchers, led by Dr. William Klein, PhD of Northwestern University, performed an extensive, well-designed, and well-controlled in vitro (outside the living body) study to test their hypothesis that DCI could be an effective therapy for Alzheimer's disease. The results were impressive to say the least. But, before they can be fully appreciated, a quick explanation of what is happening at the tissue and molecule level in the brain is in order.
At the tissue level, one of the histological hallmarks of Alzheimer's disease is amyloid- fibrils, which are a pathological accumulation of amyloid- proteins in the brain. In addition to forming fibrils, amyloid- can form diffusible ligands (diffusible meaning, in this case, mobile within the brain, and ligands being a general term for things that can bind to other things). We now know that these amyloid-derived diffusible ligands (ADDLs for short) can interact with insulin receptors. Through a long series of events, this leads to insulin resistance and decreases the amount of sugar that gets into affected neurons, effectively starving them to death. I've glossed over a lot of detail here, but you get the basics: ADDLs bind to insulin receptors and then neurons slowly starve to death.
In a nutshell, treating neurons in vitro with DCI has a similar protective effect as treating them with insulin, and treating the neurons with both insulin and DCI simultaneously has an even greater effect still. Both insulin and D-chiro-inositol were shown to protect insulin receptors found on dendrites from ADDL damage and to maintain levels of functional proteins in the dendrites at normal levels. There is really quite a bit more to the study where they also show that DCI acts as an insulin mimetic and an insulin potentiator in neurons. All in all, this study has greatly improved our understanding of Alzheimer's disease, insulin resistance and D-chiro-inositol. But, we can't count our chickens just yet a human clinical trial is necessary.
On a more personal note, about a week ago, just about the same time this leading-edge research was published, an old friend of mine lost his father to a decade-long battle with Alzheimer's. As one of the founders of a company that sells DCI, I felt a profound sadness and a great sense of irony that this new research should be published at that particular moment. I second the author's call to fast-track clinical trials related to Alzheimer's and D-chiro-inositol. We know that DCI is safe and well-tolerated from years of use in other health conditions. And now we have very good reason to believe it will help people with Alzheimer's disease as well.
If you would like to read the original study, it is available (for a fee) on PubMed, here: http://www.ncbi.nlm.nih.gov/pubmed/23073831