Alzheimer's blood test may spot disease in healthy people 3 years ahead of time

Georgetown researchers say they've developed a blood test for Alzheimer's that can spot whether a healthy person will develop cognitive declines indicative of the degenerative brain disease within 3 years.

The test identified 10 lipids -- or fats -- in the blood that were "biomarkers" that might predict disease onset and was 90 percent accurate, researchers reported March 9 in Nature Medicine.

If it is validated further, the test could provide an easier and faster way to diagnose the increasingly common brain disease. Currently, Alzheimer's is diagnosed through a complete medical assessment with cognitive tests, neurological exams (like a PET scan) and blood tests to rule out other conditions that cause dementia -- often after people have already developed memory loss and other symptoms.

A test that can spot the disease signs three years early might also allow researchers to test whether a drug could delay or prevent Alzheimer's.

"Our novel blood test offers the potential to identify people at risk for progressive cognitive decline and can change how patients, their families and treating physicians plan for and manage the disorder," study co-author Dr. Howard J. Federoff, a professor of neurology and executive vice president for health sciences at Georgetown University Medical Center in the District of Columbia, said in a statement.

Alzheimer's is a devastating disease that affects about 4.7 million Americans, rates that are expected to triple to nearly 14 million by 2050. Worldwide, disease rates are expected to double every 20 years until reaching 115.4 million by 2050, according to the World Health Organization

Current Alzheimer's drugs have failed to slow disease progression and are a "better than nothing" option to treat some symptoms temporarily. But according to the Georgetown scientists who developed the test, that may be due to the fact they are tested too late in the disease process.

"It's like giving somebody Lipitor after they've had their fifth heart attack and are in heart failure. It's too little too late," said CBS News chief medical correspondent Dr. Jon LaPook. "And the thinking is if we give it way earlier in the preventive stage, it will be more effective."

Researchers tested 525 healthy adults aged 70 and older by giving them blood tests at various points during the five-year study. By study's end, 74 people met the criteria for either mild Alzheimer's or amnestic mild cognitive impairment, a condition in which cognitive changes -- in this case memory loss -- are serious enough to be noticed by others, buy not to the point where they interfere with daily functioning.

Of the 74 patients, 46 were diagnosed at the beginning of the study, and 28 developed the cognitive declines during the study.

In year three of the study, the researchers compared 53 people who developed cognitive declines to 53 cognitively-normal people and discovered the differences in lipids.

They honed in on 10 lipids, which appeared to be caused by the breakdown of membranes in brain cells. The researchers verified these findings in the other 21 people who had cognitive declines.

"The lipid panel was able to distinguish with 90 percent accuracy these two distinct groups: cognitively normal participants who would progress to MCI or AD within two to three years, and those who would remain normal in the near future," said Federoff.

LaPook pointed out there is still more work to be done, since two out of 20 people who didn't have a cognitive issue had false positive results.

"If the test holds out over time, this could really change the way we think of risk about Alzheimer's disease," Dr. James Galvin, a professor of neurology at New York University Langone Medical Center, told CBS This Morning.

He predicts a blood test like this could come out in two to three years, and the extra heads up on a diagnosis could help patients make life decisions about their caregiving, spend more time with their grandchildren or take that trip they've always wanted.

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