Michael Douglas praised the "little blue pill" back in 2005 for its ability to help him overcome the 25-year age difference with his wife Catherine Zeta-Jones. He probably didn't think the benefits would extend to his brain.

But that's the discovery made by researchers at the Cleveland Clinic, which has the potential to revolutionize Alzheimer's disease prevention and treatment.

The researchers went through a three-step process. First they used artificial intelligence to help them discover interactions between 1,000-plus Food and Drug Administration-approved medications and receptors in the brain and body.

Then, in the lab, they saw that sildenafil (Viagra) decreased attachment of amyloid to brain nerve cells and blocked hyperphosphorylation of tau proteins — signs that brain-interfering tangles are developing.

The researchers then used insurance claim data for 7.23 million individuals to discover that sildenafil reduced the risk of developing Alzheimer's disease in men by 69%, compared with guys who didn't take it.

There were a few women taking it for pulmonary high blood pressure — and they, too, saw a decreased risk of Alzheimer's disease.

Following users and non-users for six years, the researchers also found that sildenafil reduced the risk of Alzheimer's disease by 55% compared with losartan, and 65% compared with diltiazem (they're blood pressure meds), 63% compared with metformin, and 64% compared with glimepiride (both diabetes meds).

The next step: a randomized, controlled trial to verify the preliminary findings.

Of course, don't pop the pill without doctor supervision; and stay tuned for more data. A solution to Alzheimer's disease may be on the horizon.