It's estimated some 5 million Americans are battling Alzheimer's disease, but those numbers are expected to climb dramatically in the decades to come. Now doctors have developed a simple test that can help spot problems early. And the better news is you can take the test in the comfort of your own home.

Though she spends much of her retirement traveling the world, Emily Schornstein still finds time to help with medical research. She's a retired nurse who volunteers for studies involving Alzheimer's disease. 

"Yeah, I've gotten MRIs and CAT scans, and even an LP -- a lumbar puncture," she said.

And now Schornstein is testing a new approach. This one simply involves a pen, paper and a few minutes of her time. It's called a "SAGE Test" and a new study shows it can reveal a lot about a patient's mind.

"What we found was that this SAGE, self-administered test, correlated very well with the very detailed cognitive testing," explained Dr. Douglas Scharre with Ohio State Wexner Medical Center.

A team at Ohio State's Wexner Medical Center developed the test. They gave it to more than a 1,000 patients over five years  and found nearly 30 percent showed early signs of cognitive problems they didn't know they had.

Some of the questions involve basic math while others test memory or ask test takers to identify common objects. By repeating the test from time to time, doctors have an easy way to monitor their patients and detect even slight changes.

"If we see this change, we can catch it really early and we can start treatments much earlier than we did without a test," said Scharre.

Which is crucial. Studies show most Alzheimer's patients wait three to four years before being treated. But that's not likely to happen to Schornstein.

"It's a way to maybe help me or maybe help somebody else in the future," she said.

The test doesn't diagnose diseases like Alzheimer's, but the study suggests it is an effective screening tool.

Download the free SAGE test here, but you need to take it to your doctor to have it scored.