For years, doctors have used an expensive brain scan to detect symptoms of Alzheimer's disease.
But researchers at Washington University have found that a simple blood test could be similarly effective, according to a study published this month in the journal Neurology. A blood test to diagnose early symptoms could help make finding a cure easy or cheaper and even guide treatment for the disease in the future, the study’s authors say.
“For a long time, a blood test for Alzheimer’s disease was referred to among the Alzheimer’s researcher community as the holy grail,” said Suzanne Schindler, a Wash U neurologist and author of the study. “Really, until three years ago, a lot of people thought this was far in the future.”
Alzheimer’s patients develop tangles and plaques of amyloid protein in their brains. Scientists have not determined the plaques are what cause Alzheimer’s memory loss, but they do know those proteins are present in the brain decades before symptoms start.
Doctors use a technology called a PET scan to detect those protein plaques and diagnose the disease, Schindler said. She and fellow researchers studied 150 patients and found that a blood test run through a tool called a spectrometer could detect the plaques with roughly the same effectiveness as a PET scan.
In some cases, Schindler said, the blood test predicted future Alzheimer’s symptoms better than the brain scan.
PET scans can cost $5,000 and typically are not covered by insurance, she said. And to get tested, patients need to travel to centers that have the machine. With a blood draw, the blood travels — not the person. Researchers can more easily and cheaply test for amyloid plaques.
“In terms of ease, I don’t think there’s any comparison,” Schindler said.
Scientists are starting to agree that early detection of those plaques is crucial to developing a cure. Several prospective treatments that have attacked the protein after patients began showing symptoms have failed.
Scientists think that a cure will target it during those early phases, Schindler said.
“There have been a lot of drug trials for Alzheimer’s disease that have failed,” she said. “And we think they have failed because they enrolled participants who already had significant dementia, and at that point it’s much more difficult to treat the disease.”
A blood test would make it easy to identify people in the early stages of the disease to target for testing clinical trials, which could eventually lead to a cure, she said.
“Most of them wouldn’t develop Alzheimer’s disease over the study period, so you have to have a way to identify people who are at high risk for developing Alzheimer’s disease,” Schindler said.
Far in the future, a blood test could be part of normal treatment and screening, she said.
“I could imagine maybe 20 or 30 years from now that when you go to see your primary care doctor, they take your blood and send it to check … to see if you have diabetes or high cholesterol, they also send it for an amyloid test,” she said. “If it’s positive, they start you on a medication that would prevent you from ever getting Alzheimer’s disease.”
Follow Sarah on Twitter: @petit_smudge