A Blood Test to Predict Alzheimer’s Disease

The news media made a big deal this month of the finding that a blood test has been developed that can predict (with 90% accuracy in persons over 70 years of age) who will develop Alzheimer’s disease within the next two to three years. A representative news article is this one, by NPR.

The development of a blood test to predict who is likely to develop Alzheimer’s disease sounds like a major breakthrough until you realize that at the moment there is no way to prevent Alzheimer’s from developing, and no cure once you have it. That raises an interesting dilemma; if you’re not going to benefit from being tested (prevention or cure), why be tested? Would you want to know you’re going to develop Alzheimer’s if there was nothing you could do about it except get your affairs in order?

One other fact to consider: there’s no evidence that the test can predict 40, 20, or even 10 years in advance who will get Alzheimer’s disease. The test has only been proven to be accurate within 2-3 years of the onset of Alzheimer’s. You’d have to get the test every year just to know that you were about to develop Alzheimer’s very soon. What would be the total cost of a test every year for a lifetime? The biggest beneficiaries would be your doctor and the blood-testing company.

The new test will certainly benefit researchers searching for ways to prevent Alzheimer’s, though. That’s because it will allow researchers to test potential preventative measures on people who are almost certain to get Alzheimer’s disease (as determined by the test) before the disease actually develops. That is, provided that people are willing to be tested and then to join a research study if they test positive.