At first glance, the announcment of a blood test capable of predicting the onset of Alzheimer’s disease as much as three years in advance isn’t much to celebrate. There’s still no definitive cause, effective treatment or cure of the disease that robs many senior citizens of their memory and other brain functions.

But take another look: This is a major medical development. It promises the prospects for more advancement in the fight against this still little-understood disease.

The test detects 10 types of lipids circulating in a person’s blood — lipids that serve as biomarkers, researchers said, to predict with 90 percent accuracy whether a patient will develop the memory loss and mental decline of Alzheimer’s disease over the proceeding two to three years.

The research, conducted at the University of Rochester, Georgetown University and the University of California, Irvine, could result in practical screenings as soon as two years from now, according to the study’s leader, Howard J. Federoff, a professor of neurology at Georgetown University Medical Center.

Alzheimer’s disease is becoming more prevalent, at least partly because people are living longer and effective medical treatments have lowered fatalities from other common diseases. In 2010, there were 35 million people with Alzheimer’s disease worldwide, according to the World Health Organization, which predicts this number will double every 20 years, rising to 115 million by 2050.

In the United States alone, the cost of caring for those with Alzheimer’s and other dementias was estimated to total $203 billion in 2013, according to the Alzheimer’s Association.

While there have been many attempts to produce drugs that slow or reverse Alzheimer’s, they have all failed, Federoff said. One reason could be that the drugs are tested at too late a stage of the disease. Earlier treatment, before the onset of symptoms, could be a major factor in the efficacy of treatment.

At the very least, an accurate diagnosis of Alzheimer’s disease two or three years before the onset of its symptoms can help families prepare for the hardship ahead of them not only in arranging accommodations for the patient but also arming themselves with knowledge about what to expect.

“Our novel blood test . . . can change how patients, their families and treating physicians plan for and manage the disorder,” Federoff said.

Medical battles usually are incremental — cures are discovered and developed one step at a time.

The new blood test for Alzheimer’s disease could represent a big step toward a cure — it certainly should kindle hope in a multitude of Alzheimer’s sufferers and their families.