Blood test for Alzheimer’s is nearing reality

LOS ANGELES — Scientists are closing in on a long-sought goal: a blood test to screen people for possible signs of Alzheimer’s disease and other forms of dementia.

On Monday at the Alzheimer’s Association International Conference, half a dozen research groups gave new results on various experimental tests, including one that seems 88 percent accurate at indicating Alzheimer’s risk.

Doctors are hoping for something to use during routine exams, where most dementia symptoms are evaluated, to gauge who needs more extensive testing. Current tools such as brain scans and spinal fluid tests are too expensive or impractical for regular check-ups.

“We need something quicker and dirtier. It doesn’t have to be perfect” to be useful for screening, said Maria Carrillo, the Alzheimer’s Association’s chief science officer.

Dr. Richard Hodes, director of the National Institute on Aging, called the new results “very promising” and said blood tests soon will be used to choose and monitor people for federally funded studies, though it will take a little longer to establish their value in routine medical care.

A blood test, rather than subjective estimates of thinking skills, could get the right people into studies sooner.

One of the experimental blood tests measures abnormal versions of the protein that forms the plaques in the brain that are the hallmark of Alzheimer’s.

The test correctly identified 92 percent of people who had Alzheimer’s and correctly ruled out 85 percent who did not have it, for an overall accuracy of 88 percent.

Another experimental test looks at neurofilament light, a protein that’s a marker of nerve damage.

Levels were significantly higher in eight conditions, and only 2 percent of healthy folks were above a threshold they set for raising concern.