The patch, which infuses Exelon through the skin, headlines a trio of innovative potential treatments unveiled at an Alzheimer's meeting in Spain last week. Also under study are a prostate cancer drug that may help dementia and an immune therapy to ward off the sticky gunk that is Alzheimer's brain-clogging hallmark.

It can be hard to get Alzheimer's patients to swallow pills, and Exelon can cause serious nausea and vomiting. Applied once a day, the new skin patch sends Exelon straight into the bloodstream, bypassing the gut for fewer side effects and maintaining a consistent daylong dose.

Doctors noticed some men with both Alzheimer's and prostate cancer seemed to fare better cognitively while taking leuprolide. If the effect was real, it was puzzling: leuprolide blocks a hormone that in turn decreases the brain-protective sex hormones testosterone and estrogen. Then newer research suggested leuprolide had another effect, reducing beta-amyloid in mice.