Diagnosing Alzheimer’s disease has been a complicated process that involves a clinical evaluation from a neurologist and either brain imaging tests or a spinal tap.
The imaging test most often used is a specific positron emission tomography (PET) scan, which shows the presence of amyloid plaques—a hallmark of Alzheimer’s—in the brain. It is costly and not universally available, while a spinal tap (lumbar puncture) is invasive and involves a needle inserted into the lower spine to collect cerebrospinal fluid to look for certain proteins that could signal Alzheimer’s.
But now doctors have a new tool: an Alzheimer’s blood test. The Food and Drug Administration recently approved the first test that uses a blood sample to help diagnose Alzheimer’s disease. The disease, which causes a decline in memory and thinking skills, affects nearly 7 million Americans—and is projected to become more prevalent.
The test, called Lumipulse and made by Japan-based Fujirebio Diagnostics, is for adults 55 and older who show signs of Alzheimer’s disease, the most common form of dementia (a broad term used to describe a decline in cognitive abilities). It is not intended to be a general screening test for people who are asymptomatic, and it is not designed to diagnose other types of dementia, such as vascular dementia, Lewy body dementia, and frontotemporal dementia.
The blood test’s convenience will allow providers to diagnose Alzheimer’s sooner, which is important because the only approved medications for Alzheimer’s disease—Leqembi and Kisunla—are geared toward slowing progression of the condition in its early stages.
“This is great news, and when it’s fully implemented, it will be a game changer in some ways,” says Sayed Azizi, MD, PhD, Yale Medicine’s clinical chief of neurodegenerative disorders. “But there are many nuances to consider.”
The test, Dr. Azizi says, fits into a larger diagnostic process and only makes sense to do after a doctor has determined that a person has memory or cognitive problems. The first step, always, is a clinical evaluation in which your symptoms and medical history are considered.
“If a patient comes to a physician with memory complaints, we offer a clinical evaluation to assess and perhaps quantify the cognitive problem,” says Dr. Azizi, adding that conditions such as diabetes, hypertension, and depression can cause memory and cognitive issues.
The Alzheimer’s blood test, Dr. Azizi explains, can help determine whether Alzheimer’s disease is the cause of the symptoms. “When it comes to dementia, 60% to 70% of cases are caused by Alzheimer’s, and the other 30% to 40% can be a sundry of different things,” Dr. Azizi says. “Because Alzheimer’s is the largest percentage, we concentrate on it and want to diagnose it so that we can treat it.”
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