Brain training is big business these days. There are online brain training websites, phone apps, and gadgets. There are even retail stores devoted to games and technology designed to stimulate your mind and keep it sharp, well into old age.

The goal of brain training is to improve cognitive function through repetitive exercises, like problem-solving and memory games. It's all in an effort to stave off dementia. And there's a good reason to worry about it.

Worldwide, nearly 36 million people are living with Alzheimer's disease or dementia. But unless there's some kind of breakthrough, in just 17 years, that number will double.  And by 2050, rates could exceed 115 million!

But do you need fancy $400 software - or a cognitive coach - to keep you sharp? Not according to Rush University Medical Center. They say some pretty low-tech activities can work just as well - like writing letters and reading the newspaper. 

In their study, they followed 200 seniors who averaged 81 years old. And those who did simple mental exercises had brains that were much “younger” than those that didn’t. That’s because, as we age, the structure of our brain gets less dense. But challenging our gray matter slows the deterioration and actually increases the number of nerve fibers and connections that send information around our brain – making us able to think faster, and better able to retrieve memories.

Bottom line: Any type of activity that engages your thought process boosts your brain health. That includes playing cards and board games, like chess, going to the theatre and the library and reading books, newspapers and magazines.