It's a fact: people middle-aged or older who solve word games and brainteasers stay smarter longer than those who don't. Vetted by a neuroscientist, 399 games stimulate the formation of neurons and literally re-grow your brain. Plus they're fun. Arranged from easiest to hardest, each is labeled according to which cognitive functions they exercise, so you can create your own custom brain workouts. Softcover, 424 pages.