Here is an article from Pakistan’s Mensa chapter on how to keep the brain fit, called “How to Improve Your Memory & Exercise Your Brain?” Here’s tip #2
2. Keep your brain active. The brain is not a muscle, but regularly “exercising” the brain actually does keep it growing and spurs the development of new nerve connections that can help improve memory. By developing new mental skills—especially complex ones such as learning a new language or learning to play a new musical instrument—and challenging your brain with puzzles and games you can keep your brain active and improve its physiological functioning.

