"It keeps my mind active, and it gives me a lot of pleasure," Iacono said.

The orchestra's executive director and co-founder, Vito Saritelli, said Iacono is extremely sharp for his age.

"Music has played a good part of his longevity," said his wife, Mary Iacono, 94. "We're blessed that we're both in good health."

As scientists race to figure out how to promote healthy aging of the brain, and prevent dementia, their preliminary advice for senior citizens has become a chorus of voices: "Stay active! Have hobbies! Be socially engaged!"

Playing music, for some people, is a natural answer to all of those recommendations. Frank Iacono, for instance, has been playing violin since he was 13 -- just because he loves it.

But does music playing in particular stave off dementia? What about just listening to music? How many years do you need to engage in music before it benefits your brain?