A new blood test may help doctors diagnose Alzheimer’s disease more quickly and accurately, a new study has found.
Alzheimer’s disease is the most common form of dementia, affecting 6.7 million Americans, a number that is expected to rise to 13 million by 2050 as the U.S. population ages rapidly.
A study of 1,213 patients in Sweden from February 2020 to January 2024 published Sunday found that a blood test focusing on one form of a protein called tau was far more accurate than a doctor’s diagnosis alone.
In the study, patients who visited their GP or specialist with complaints of memory problems received an initial diagnosis through conventional testing, had their blood drawn for tests, and underwent a confirmatory spinal tap or brain scan.
A study by researchers from Lund University found that an initial diagnosis by a general practitioner was 61% accurate, a diagnosis by a specialist was 73% accurate, but blood tests were 91% accurate.
A blood test that focuses on one form of a protein called tau is much more accurate than a doctor’s diagnosis alone, according to a new study.
Scientists believe that Alzheimer’s disease is likely caused by the buildup of abnormal proteins (amyloid and tau) in and around brain cells.
“Until recently, it was thought that it was impossible to measure pathology in the living human brain,” Dr. Jason Karlawish, co-director of the Penn Memory Center at the University of Pennsylvania, who was not involved in the study, told The New York Times.
“This work further contributes to the revolution in our ability to measure what is going on inside the living human brain.”
The primary cause of Alzheimer’s remains debated, but scientists think the damage likely results from the abnormal buildup of proteins such as amyloid and tau in and around brain cells.
In people with Alzheimer’s, amyloid proteins are not effectively cleared from the body and eventually form plaques in the brain. Tau proteins break off from neurons and form tangles.
Both of these can lead to the death of neurons, making it difficult for them to send signals throughout the brain.
The blood test measures a form of tau that correlates with the amount of plaque buildup, said Dr. Suzanne Schindler, a neurologist at Washington University in St. Louis.
High levels indicate a high likelihood of Alzheimer’s disease, while low levels indicate it is unlikely to be the cause of memory loss.
Experts said the blood test should be restricted to use by doctors and researchers and not be widely available to the public.
Maria Carillo, chief science officer at the Alzheimer’s Association, said only blood tests proven to be at least 90% accurate should be used.
The Alzheimer’s Association is working on developing guidelines, and several companies plan to seek FDA approval to clarify appropriate use.
Schindler said people without symptoms cannot be tested unless they are taking part in a research study.
Alzheimer’s disease is the most common form of dementia, affecting 6.7 million Americans.
One reason is that amyloid buildup can begin as much as 20 years before the first signs of memory loss appear, and so far there is no preventative measure beyond basic advice of a healthy diet, exercise and enough sleep.
There is currently no cure for Alzheimer’s, but new drugs such as donanemab, taken twice a day, can lower levels of a harmful brain protein called amyloid, but they only slow the disease’s progression slightly and come with dangerous side effects such as brain hemorrhage.
The drug was initially hailed as a potential treatment, but a quarter of patients in clinical trials suffered brain swelling and three died from brain swelling or bleeding caused by the drug.
Another drug, Requenvi, works similarly to donanemab but can also cause amyloid-related imaging abnormalities (ARIA), brain changes that include bleeding and swelling.
Although the drug is FDA approved, studies have shown that approximately 20 percent of people who take the drug develop ARIA, but only 20 percent of those experience symptoms.