Statistics Canada says nearly three quarters of a million Canadians have Alzheimer's or some other form of dementia. One new case is diagnosed in Canada every five minutes.  Researchers in the US are close to developing a simple blood test that can diagnose Alzheimer's.  The science is complex.  So are the implications.
It's a blood test that measures something called autoantibodies. Our immune system makes antibodies to fight off viruses and other infections.  Those are the good kind.  The body also makes autoantibodies - antibodies that attack your own body tissues.  Every one of us possesses thousands of these autoantibodies in our blood stream.  Turns out that diseases like Alzheimer's cause typical changes in the profile of those autoantibodies.  Doctors call these autoantibodies biomarkers. These can be measured in a blood test that gives doctors a very accurate read on whether or not you have Alzheimer's.

Biomarkers are also being tested in Parkinson's and other chronic diseases.

Robert Nagele and colleagues at Rowan University School of Osteopathic Medicine measured a panel of these biomarkers in people with mild to moderate Alzheimer's disease and compared them to a group of people of the same age who don't have Alzheimer's.  The test was both highly sensitive at detecting people with Alzheimer's - which means it's unlikely to miss people who have the disease. It was also highly specific, which means the test is unlikely to label someone with Alzheimer's who doesn't actually have it.  

Nagele present his latest findings at a meeting of the American Osteopathic Association, as reported in Medical News Today.

Not only does the test allow early diagnosis of Alzheimer's it also offers the possibility of diagnosing Alzheimer's before symptoms appear.  That enables the person to make lifestyle changes that could slow down the progression of the disease. These include things like losing weight, getting more exercise as well as getting cholesterol, triglycerides and diabetes under control.  A test that affords very early detection would also identify a group of patients who would be good subjects for clinical trials of possible drug treatments.

Researchers familiar with this line of study say that a blood test for Alzheimer's based on biomarkers is considered the holy grail of early detection.  Researchers at UCLA reported in March of this year that the test is feasible.  But some say not enough people with Alzheimer's have been tested to draw firm conclusions.  They say the expertise on testing is confined to a small number of researchers, and that no one knows how well the test will stand up when labs around the world begin doing the test.  

Last year, an interest group made up of leading Alzheimer's researchers from academia and from the pharmaceutical industry was formed to developed gold standards on individual blood tests, testing procedures, and how to interpret the tests.

The implications of easy-to-do blood testing are huge.  There are commercial interests working on just that - similar to getting your genome sequenced.  It's one thing for a test like that to tell you've got Alzheimer's; quite another to know what to do with that information.  For instance, it's common for people diagnosed with Alzheimer's to become depressed.  Someone who gets a positive test for Alzheimer's is going to need a lot of support from their doctor. Beyond the personal implications, does your insurance provider have a right to know the result?  You may think you're entitled to privacy, but if you don't tell your provider, they may be able to say you had a preexisting illness and didn't tell them.

I'm not with cutting edge researchers on this one.  I think a biomarkers blood test would be very helpful were effective treatment available.  Given the current barren landscape, it is little more than a recruitment machine for drug companies looking for subjects for clinical trials.