If you’re older than 26, you’re already starting to lose your marbles, says By 27, says a new study of brain function, your brain begins a slow decline toward the fog of dementia. Study author Timothy Salthouse of the University of Virginia performed cognitive tests on 2,000 healthy people between the ages of 18 and 60, studying their ability to solve puzzles, recall words and story details, and spot patterns in an assortment of symbols. He found that the age for peak mental performance is 22. By age 27, there was a marked decline in brain speed and puzzle-solving skills. Memory skills, he says, can keep pace for a longer time, remaining strong until around age 37, when they start going downhill. Fortunately, Salthouse finds, we do gain wisdom as we age, with both our vocabulary and general storehouse of knowledge growing until at least age 60.