Cognitive engagement means being mentally active: keeping your brain thinking and working hard. When you use your brain in new and challenging ways, new connections are built between brain cells. The more connections it has, the more nimble your brain is. This can protect your brain against the effects of injury or brain disease, possibly lowering the risk of Alzheimer's and other dementia.

As children, we are constantly learning and building a "cognitive reserve," or a bank that we carry with us into older age. As adults, we need to keep learning new things and keep our brains active.

What can I do to challenge my mind?

Many types of activities are cognitively engaging — including brain games, mental exercises and fun hobbies. The activities you choose to challenge your mind should be interesting or fun to you so you continue to learn and do them.

Try learning a new skill or language, adopting a new hobby or taking a class on something you don't know a lot about. You could learn how to play an instrument, try an art form or learn to play a strategy game. Activities challenge people differently. The key is to keep your brain working hard. Once an activity becomes easy, such as figuring out the strategy to help you solve a puzzle, it's time to add something new. Keeping your mind challenged may have short- and long-term benefits for your brain, so stay curious.