The eye -- window into the brain?

My ophthalmologist once told me that the eye has more nerve connections to the brain than any other part of the body.  He had a number for how many connections there are, but I don't remember what it was.  I read elsewhere that some neuroscientists consider the eye to simply be an extension of the brain.  Consistent with that view, it turns out that beta amyloid can be found in the retina.  Of course, we understand the generation of beta amyloid and its destructive effect on brain cells to be a central feature of Alzheimer's disease.  So, if the eye is part of the brain, whatever is going on in the brain proper would also be going on in the eye.

My friend Mike in Virginia sent me this article last week about research into biomarkers for Alzheimer's disease and Parkinson's disease "focusing" on what can be found on the retina of the eye.  The hope is that such biomarkers can provide an early diagnosis of pre-clinical disease -- before the first symptoms appear.  This can help with research, because it is believed that emerging treatments will work better the earlier in the course of the disease they are applied. 

As far back as 2018, we have discussed the value of inexpensive and easily observed biomarkers in the diagnosis of Alzheimer's disease.  Currently, doctors and researchers may use expensive MRIs and PET scans, but there is hope that blood tests will soon provide cheaper and earlier diagnosis.  So the idea is that, in the future, pretty much the same equipment your optometrist uses to check for glaucoma can be used to help diagnose Alzheimer's disease.

The article focused on the work of the leaders of two different research teams:

• Maya Koronyo-Hamaoui at Cedars-Sinai in LA who leads a team that has been developing a technique for finding amyloid plaques in the retina using a machine similar to that used in an ophthalmologist's exam.  The cost is said to be about $285 per scan.
• Ruogu Fang, an electrical engineer specializing in AI working at the University of Florida, leads a team learning to use an iPhone image to examine blood vessels in the retina. 
  

In the case of Koronyo-Hamaoui's device, the subject drinks a liquid containing curcumin, the substance that gives the spice turmeric (and hence, curry) it's flavor.  (This will resonate with those of us who love Indian food.)  The curcumin has an affinity for beta amyloid, and it can be detected by shining blue light on it.  So blue light can be used to identify amyloid plaques developing in the retina.

Fang's iPhone technique looks for changes in blood vessels associated with Parkinson's disease, but not Alzheimer's.

Early detection of Alzheimer's disease continues to be an important area of research.  The downside is what it will mean for those seeking long term care insurance.  I remember that when I applied for long term care insurance (before I had cognitive issues), they examined me very closely for memory problems.  

 

I'll speculate.  A person with a positive test for beta amyloid, but prior to cognitive symptoms, will be unable to get insurance at a reasonable price.  The insurance companies will likely insist on the tests unless curbed by legislation.  A person who tests negative my not see a justification for the cost of insurance.  This could be destructive to the industry.

 

It may not be a wise decision to skip insurance, especially since the price might go lower with Alzheimer's patients ruled out.  There are many other causes of dementia and other debilitating diseases that afflict the elderly.  

The biomarker blood tests have not rolled out as quickly as I had hoped.  We'll see what unfolds in the coming months.