NEW YORK — Imagine being treated for a disease before you even have it.

That will soon be possible thanks to emerging technologies that make diagnosing illness easier and faster.

“We’re waiting for the heart attack, or we’re waiting for the lump to be discovered at stage three,” Dr. Daniel Kraft told an audience last week at the Exponential Finance conference in New York City. No more. He said it will one day be diagnosed at stage zero — and there’s already progress in this direction.

“What if we could see inside the brain of a patient 10 or 20 years before they develop clinical signs of Alzheimer’s? That’s now possible with new scans,” Kraft said.

It could also be done with new advances in blood-based biomarkers. A study, released last year, found that biomarkers could predict Alzheimer’s before it starts by using a simple blood test.

Those results are preliminary, but important: catching Alzheimer’s early is crucial, especially since the number of Americans suffering from it will increase. The Alzheimer’s Association estimates that by 2050, the number of people with the disease could triple, from 5.1 million to 13.8 million.

There’s also a new eye test that predicts dementia. The testing is still in the early stages, but it’s based on research at Duke University, which found that differences in the sizes of blood vessels in the eyes can predict dementia before its onset. That’s important because patients are usually treated after they’ve already endured irreversible brain damage.

There’s also the reinvention of the stethoscope. Kraft said some stethoscope apps can do a better job of picking up a heart murmur than he can, and what’s more, anybody can use them.

“A nurse or medical student can have the skill of a cardiologist using these apps,” Kraft said.

It’s even possible that the 200-year-old stethoscope could be completely replaced by a hand-held ultrasound device. It allows doctors to see inside someone’s chest, instead of just listening in. That picture offers doctors another way to interpret what’s happening inside the body.

Doctors are also going to get much smarter thanks to artificial intelligence.

Two years ago, IBM announced that Watson, its very smart computer system, had learned enough so it was comparable to a second-year medical student. Since then, it has been working with the Memorial Sloan-Kettering Cancer Center in New York and Wellpoint, a healthcare company, to learn even more.

That knowledge makes Watson a useful sidekick for doctors when it comes to offering opinions and helping physicians pick the right drug or the right therapy.

Kraft spoke of Watson and the massive amount of data it can organize, reference and learn from.

“As a physician, there’s no way to keep up with this avalanche of data,” Kraft said. “So we need new tools.”