Doctors and researchers have long been seeking an accurate test for predicting the likelihood that an otherwise healthy person will develop Alzheimer’s Disease (AD). Up until this time, the only really reliable diagnosis for the disease had to be made well after the patient had developed dementia, and certainty was only possible post-mortem since distinguishing Alzheimer’s Disease from other causes of dementia had to be done by examining brain tissue, and no really safe method of biopsying brain tissue in living patients exists at this time. Other methods currently in use for predicting AD include PET scans and spinal taps, which can be risky, unreliable, impractical, and expensive.
Now, in a landmark study published in “Nature Medicine,” researchers have developed a blood test for predicting AD with 90 percent accuracy. The quest for such a test began before anybody had a clue what sort of molecules they should be looking at – DNA, RNA, proteins, or lipids? In the interests of time and convenience, they settled on lipids, as the easiest and cheapest. The study involved drawing blood from hundreds of healthy people over the age of 70 from populations in New York and California. Five years later, 28 of those seniors developed AD, or were beginning to evidence the slight cognitive problems that signal its onset. Upon examining more than 100 fats in the lipid profile of the seniors who had developed the disease, they found low levels of 10 particular lipids, when compared with the blood of the healthy seniors. The researchers then examined the blood of 54 other patients who had AD or were beginning to experience symptoms: this group also had low levels of the suspect lipids.
Dr. Mark Mapstone, of the University of Rochester Medical Center and lead author of the study, gave a sense of how the valuable the test might prove to be. The test they developed can predict Alzheimer’s Disease before the patient shows any symptoms, suggesting that the pathology may begin well before people’s memories begin to fail. He further suggested that it was possible the lipid levels might start to decrease as the brain cells began to die.
Dr. Mapstone and his team are looking to try their test in younger people in the 40s and 50s age bracket. If successful, he says, they would have the “holy grail.” Studies involving experimental drugs and treatments are much more valuable when they can be administered to a defined group that is definitely going to get the disease.
Meanwhile, research into other possible tests for Alzheimer’s is ongoing. A recently released report puts mortality from AD at around the same levels as heart disease and cancer, highlighting an urgent need to find a reliable diagnostic for the illness. The transition from experimental research and development to clinical use for a diagnostic test for AD is expected to take years, since the test will require validation by other labs will require recruitment of other test subjects to include racial and ethnic data.
Dr. Howard Federoff, neurologist at Georgetown University Medical Center expressed enthusiasm for the report, calling it a “game-changer.” Heather Snyder, spokeswoman for the Alzheimer’s Association, was more cautious, saying the study was interesting and intriguing, but very preliminary. For patients and families, a reliable test for the prediction of Alzheimer’s Disease, although perhaps unwelcome news, might be very useful in life planning – checking items off the bucket list, and making family arrangements. Although some might not want to know they were likely in for a devastating disease which is, as yet, untreatable; patients and families might want to avail themselves of counseling.
By Laura Prendergast