Blood test could help diagnose Alzheimer's earlier

Diseases that limit our ability to interact with family and friends are particularly difficult. A new study in Nature Medicine shows promise for a new blood test in Alzheimer’s dementia.


Dementia is a brain disease and limits a person’s ability to function. Its symptoms include memory loss, difficulties with speech and inability to find one’s way around the house. Alzheimer’s is the most common type of dementia and typically seen in elderly patients. Once it starts, there are no cures and few options for treatment. Currently, the disease is diagnosed by excluding other causes of abnormal brain function and using a series of cognitive tests, like naming objects and drawing a clock.

Significant research efforts are underway to detect Alzheimer’s disease early. The hope is that early detection, combined with early intervention, can help slow or even reverse the disease. Until now, no blood test had been able to accurately diagnose Alzheimer’s.

In a new study, Dr. Mark Mapstone, associate professor of neurology at the University of Rochester, and colleagues followed 525 patients age 70 and older over a 5 year period. Researchers periodically drew blood from participants. They compared results between patients who developed Alzheimer’s disease versus those who did not. They found that a group of 10 molecules in the blood of normal patients was able to predict with 90 percent accuracy who would or would not develop Alzheimer’s in the next 2-3 years.

Dr. Mapstone’s results are very exciting. A blood test for Alzheimer’s, particularly one that could diagnose the disease before symptoms develop, would be a major breakthrough. It would be convenient, potentially less expensive, and less time-intensive than current methods of diagnosis.

Patients should be cautioned that the blood test needs to be confirmed in a larger group of patients before it will become widely available. In addition, early detection by itself offers little benefit to patients. The real benefit will be if early detection of Alzheimer’s actually leads to slower progression or reversal of the disease.

Although significant work is still needed going forward, Dr. Mapstone’s study may have unlocked a key step in diagnosing Alzheimer’s disease early.