Jose Belardo of Lansing, Kan., spent most of his career in the U.S. Public Health Service. He worked on the front lines of disasters in such places as Haiti, Colombia, Nicaragua and the Dominican Republic.

At home with his three kids and wife, Elaine, he’d always been unfailingly reliable, so when he forgot their wedding anniversary two years in a row, they both started to worry.

“We recognized something wasn’t right and pretty much attributed it to being overworked and tired,” Elaine said.

But the symptoms grew. Last year, when Jose was 50, he got an evaluation at the Walter Reed National Military Medical Center that included a battery of cognitive tests and an amyloid PET scan of his brain. The scan detects beta-amyloid plaques — sticky clumps of protein fragments that tend to build up particularly in the brains of people with Alzheimer’s disease (though some healthy older adults have these plaques, too).

Jose said his diagnosis of early-onset Alzheimer’s disease came as an inconvenient shock. Still, he and his wife said they believe it is better to have a diagnosis than not. Jose said he is determined not to let the shock of the diagnosis distract him from living a full life.

“I’ve got responsibilities, man. I can’t go away,” Jose said. “I’ve got kids. I’ve got graduations coming up. I’ve got all this stuff coming up. I’m not going to let Alzheimer’s take that away from me. That’s for sure.”

The prospect of having Alzheimer’s can be so scary, and the current treatment options so few, that many people dismiss memory problems or other symptoms rather than investigate them, say Alzheimer’s specialists; it’s estimated that as many as half of all cases aren’t diagnosed.

But that may soon change. Researchers are making progress in measuring beta-amyloid and other Alzheimer’s biomarkers in blood that might eventually be able to reliably, inexpensively and non-invasively identify the disease years before cognitive symptoms develop.