Alzheimer’s disease affects more than 6 million people in the U.S. and millions more around the world, with dementia being the most common form. The revealing biomarkers are brain-clogging amyloid plaques and abnormal tau protein. However, new blood tests have been found to detect the characteristics of Alzheimer’s disease more accurately.
Two new drugs, Kisunla and Leqembi, can remove the gooey amyloid from the brain. This can modestly slow symptoms as they worsen. However, they only work in the earliest stages of Alzheimer’s. Therefore, proving your patients qualify in time can be a challenge. It’s invasive to measure amyloid in spinal fluid; using a PET scan to spot plaques is costly; and getting an appointment can literally take months.
While blood tests have been used mostly in carefully controlled research settings, it’s been shown that they can also work in doctors’ offices, thanks to a new study in Sweden of around 1,200 patients.
As part of the study, patients who visited a primary care doctor or a specialist for memory issues were initially diagnosed using traditional examinations, had blood work done, and were sent for a spinal tap or brain scan for confirmation.
The blood testing was significantly more accurate, according to Lund University researchers. According to the findings, the initial diagnosis from primary care doctors was 61% accurate. The specialists’ was 73%. But the blood test was 91% accurate, according to the findings, which were published in the Journal of the American Medical Association.
It’s not easy to tell if Alzheimer’s causes memory issues. The only way to know is to confirm buildup of a sticky protein known as beta-amyloid with a brain scan or uncomfortable spinal tap. Instead, a lot of patients are diagnosed based on their symptoms and cognitive tests.
There are a variety of tests today, and each one measures different biomarkers in different ways. According to the Alzheimer’s Association, only blood tests proven to have a greater than 90% accuracy rate should be used by doctors and researchers. The tests most likely to meet that benchmark are called p-tau217. They measure a form of tau that correlates with how much plaque buildup someone has. A high level signals a strong likelihood the person has Alzheimer’s. A low level indicates it’s probably not the cause of memory loss.
ALZpath Inc., Roche, Eli Lilly, and C2N Diagnostics are some of the companies that are developing p-tau217 tests. However, only doctors can order the tests from the labs. The p-tau217 blood test seems to be the front-runner for Alzheimer’s and with the most validity.
The peptide p-tau217 is unique because it can only be detected when amyloid plaques are present in the brain. That means when p-tau217 is being measured, the neuron damage from tau is being measured very early on in Alzheimer’s, but only when amyloid is already present.
The Alzheimer’s Association is working on guidelines and several companies plan to try for FDA approval, which would define proper usage. In the meantime, doctors should use blood testing only in patients who have memory problems, after checking the accuracy of the type they order.
According to mathematical models based on the aging of the U.S. population, wait times for testing are going to get worse. If in 10 years a primary care doctor is still only using the current cognitive assessments to determine dementia, people will have to wait an average of about six years.
There aren’t tests for people who don’t have symptoms just yet, partly because amyloid buildup can begin two decades before the first sign of memory issues. So far, there aren’t any preventive steps other than basic advice to eat healthy, exercise, and get enough sleep.
More articles from the December 2024 issue:
- Diagnosing Alzheimer’s Disease
- Patient Medication Reviews
- A New Direction for Continuous Glucose Monitors
- The Prevalence of Osteoarthritis
- Vaccine Overview 2024-25
- Peripheral Artery Disease
- PBMs Exposed
- Cybersecurity in Your Pharmacy
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