A host of studies in the past decade have shown that the more mature brain actually has advantages over its younger counterpart. These findings came as a surprise to many people, who were accustomed to seeing "senior moments"—groping for the right word or taking longer to articulate your thoughts—as a sign that the brain was on the skids. Yet even in professions where youth is valued, testing has shown that maturity has advantages. For example, in a study of air-traffic controllers and airline pilots, those between ages 50 and 69 took longer than those under 50 to master new equipment, but once they had, they made fewer mistakes using it. (Keep this in mind when you're trying to conquer a new computer program or adapt to a new car!)

The mastery that comes with maturity is due to changes in your glands as well as your brain. Declining levels of testosterone—even in women—result in better impulse control. The end of the hormonal roller coaster of perimenopause may also contribute to emotional stability. After midlife, people are less likely to have emotional issues like mood swings and neuroses that interfere with cognitive function.

Most importantly, the wealth of knowledge from decades of learning and life experience enables you to better assess new situations. At midlife, most people are more adept at making financial decisions and getting to the heart of issues than they were when they were younger.

In most people, these abilities improve with age:

• Inductive reasoning. Older people are less likely to rush to judgment and more likely to reach the right conclusion based on the information. This is an enormous help in everyday problem solving, from planning the most efficient way to do your errands to managing your staff at work.

• Verbal abilities. In middle age, you continue to expand your vocabulary and hone your ability to express yourself.

• Spatial reasoning. Remember those quizzes that require you to identify an object that has been turned around? You are likely to score better on them in your 50s and 60s than you did in your teens. And you may be better at some aspects of driving, too, because you are better able to assess the distance between your car and other objects on the road.

• Basic math. You may be better at splitting the check and figuring the tip when you're lunching with friends, simply because you've been doing it for so many years.

• Accentuating the positive. The amygdala, the area of the brain that consolidates emotion and memory, is less responsive to negatively charged situations in older people than in younger ones, which may explain why studies have shown that people over 60 tend to brood less.

• Attaining contentment. Years ago, researchers were surprised to find that people seem to be more satisfied with their lives as they age, despite the losses that accumulate with passing years. This is probably because they tend to minimize the negative, accept their limitations and use their experience to compensate for them, and set reasonable goals for the future. Dr. Yankner notes that this trait may be innate, because it is prevalent even in the United States and other Western nations, which tend to value youth over age.