Blood tests for Alzheimer's disease? When?

It seems like every month there's a new story in the news about the advancement of another blood test for Alzheimer's disease.  A couple of tests are out there, but they're rarely used.  Yes, they're new, but why not use them more often?

We have discussed blood tests on this blog several times in the past, noting that they could shake the availability of long-term care insurance for many people.  The blood tests appear to identify the disease well before the first symptoms appear, so insurance companies will be unwilling to insure people long term who are found during screening to be already developing the disease.

Here's an interesting article from the Washington Post via Yahoo News about what's going on with this.  (Ah, The Washington Post.  Sixty years ago, I would get out of bed each morning at 4:30 or so to go deliver the Post on my paper route.) 

The Post article explains that the medical and health care communities are not ready to proceed with making the tests generally available for people with no symptoms.  The tests are being used to screen candidates for Alzheimer's drug clinical trials to ensure people with memory loss are actually suffering from the disease.  But what about use in a primary care setting?  What about primary care providers diagnosing people who may be suffering from normal pressure hydrocephalus (NPH)?  They have very similar symptoms to Alzheimer's disease, but the treatment is usually different.  NPH is often misdiagnosed as Alzheimer's disease.  Tests for NPH can be quite intrusive -- such as a spinal tap.  So why not screen out Alzheimer's disease first?

Medicare and health insurance companies are not ready to cover the blood tests.  Out of pocket, costs run from $500 to $1,200.  This is a lot cheaper than an amyloid PET scan (more than $5,000), which is the current gold standard for diagnosing Alzheimer's disease.  Of course, the final diagnosis is in the autopsy, but most people don't want to wait that long.

The article emphasizes that opinion on the tests is quite divided.  Some would make the tests freely available now, while others believe that the consequences of their use must be better understood before they're more broadly used.  No one has said anything about the possibility that the tests could disrupt the availability of long-term care insurance, but I'd bet that's a factor.