Scientists at Columbia University have found a new way to predict when people at high risk for Alzheimer’s disease will show their first symptoms. This discovery could help doctors decide the best time to start preventive treatments as they become available.
The research was published in The Lancet Neurology journal. The team studied information from about 8,500 people from many different ethnic groups. They discovered that combining two tests gives much better predictions than using either examination alone.
The first test is a blood test. It measures a substance called p-tau217. The second test is a genetic test. It checks for a risky version of a gene called APOE. When researchers combined the results of both tests, they could predict when symptoms would begin, even in people who currently show no signs of the disease.
Here is what they found. Once p-tau217 levels rise in the blood, people who carry one or two copies of the high-risk APOE4 gene tend to develop symptoms within three to four years. People with other versions of the APOE gene tend to develop symptoms a bit later, within five to six years.
Dr Richard Mayeux led the study. He is the chair of the Department of Neurology at Columbia University Vagelos College of Physicians and Surgeons. He also serves as neurologist-in-chief at NewYork-Presbyterian/Columbia University Irving Medical Center. He explained that using both tests together greatly improves the accuracy of predictions. He also noted something important: the results held true across all the different ethnic groups studied.
Mayeux believes this discovery could change how doctors treat high-risk patients. Once new preventive drugs are approved, doctors could use these tests to know exactly when to start treatment for each patient.
Blood tests for p-tau217 are already changing how Alzheimer’s is diagnosed. Over the past few years, doctors have started using these tests regularly. They help confirm or rule out Alzheimer’s in older adults who show memory problems or thinking difficulties. The p-tau217 biomarker reflects two harmful changes in the brain: amyloid buildup and tau tangles.
Interestingly, some people show high p-tau217 levels before they have any symptoms at all. This raised an important question for researchers. Could this blood test alone predict who will develop Alzheimer’s in the future? Unfortunately, the answer was no. Using p-tau217 by itself was not accurate enough to make reliable predictions.
This is why Mayeux’s team decided to test a new approach. They wanted to see what would happen if they combined the p-tau217 blood test with a test for the APOE4 gene. APOE4 is already known as the strongest genetic risk factor for Alzheimer’s disease. About one in five people carries at least one copy of this gene.
Despite these promising results, Mayeux is cautious. He does not recommend that healthy people get tested right now. His reasoning is simple. Currently approved Alzheimer’s drugs are only available to patients who already show symptoms. People without symptoms cannot yet benefit from these treatments, so testing offers them no practical advantage today.
That said, the situation may change soon. Scientists are currently running a new study. It aims to discover whether antibody drugs can slow the disease when given to people who have no symptoms but do have elevated p-tau217 levels.
Many other new drugs are also being developed. Researchers hope these drugs will slow Alzheimer’s disease. This new testing approach could play a key role in future clinical trials for these drugs.
Mayeux summed up the significance of the findings. He explained that if a drug exists that can prevent the disease, doctors need to know the best time to administer it. According to their data, the ideal moment for people with the APOE4 gene is right when their p-tau217 levels start rising, roughly three years before symptoms would normally appear.
