In the future, blood tests may play an outsized role in the early diagnosis of people living with cognitive decline.

In a newly published story in science magazine Scientific American, neurologist and neuroscientist Suzanne Schindler explored how blood tests are becoming an important tool for the detection and early treatment of Alzheimer’s.

When an older adult is suspected of having dementia, a common response is to observe them and watch for signs of cognitive decline over time.

“Some patients improve after interventions such as stopping a medication or starting treatment for sleep apnea. Some patients continue to experience cognitive difficulties but never really worsen,” Schindler wrote. “And some patients progressively decline until it becomes clear that they have a neurological disorder. Which leads to another difficult question: Are their symptoms caused by Alzheimer’s disease?”

With the advent of new treatments and drugs pushing the memory care sector into the future, it’s that last group – people who are eventually diagnosed with cognitive decline – that could benefit the most.

When people do receive a dementia diagnosis, it is often at an advanced stage when early treatments, such as the drug lecanemab, are not as effective, Schindler wrote. Although clinicians can detect myloid proteins in cerebrospinal fluid using a technique approved by the FDA in 2022, such procedures – although safe and effective – can be scary for patients.

Another option for diagnosis are PET scans that use special imaging to detect a radioactive tracer material that binds to amyloid plaques. But those treatments are expensive, and such procedures are still not common, Schindler wrote.

By comparison, blood tests are already common in hospitals and health care settings. And crucially, the blood tests appear accurate enough to detect Alzheimer’s in the vast majority of cases.

“After much discussion with colleagues, we generally agree that blood tests used in clinical diagnosis … ideally would correctly classify 90 to 95 percent of patients,” Schindler wrote. “Some of the newest blood tests meet this high threshold, especially because they can categorize individuals as positive, negative, and intermediate.”

Already, there are more than a dozen blood tests for Alzheimer’s underway in some shape or form. And looking ahead, Schindler said she expects them to “become the dominant approach to testing for Alzheimer’s disease brain changes within a few years.”

“We could enter a time where primary care clinicians screen cognitively normal older individuals at annual visits with blood tests to see whether they have Alzheimer’s brain changes,” she wrote. “This may herald an era when Alzheimer’s disease becomes a chronic medical management issue, like high cholesterol, rather than the devastating illness that we know today.”