Why you should thank your aging brain

Harvard Women's Health Watch

At middle age, the brain begins to draw on more of its capacity for improved judgment and decision making.

If you forget a name or two, take longer to finish the crossword, or find it hard to manage two tasks at once, you're not on the road to dementia. What you're experiencing is your brain changing the way it works as you get older. And in many ways it's actually working better. Studies have shown that older people have better judgment, are better at making rational decisions, and are better able to screen out negativity than their juniors are.

Although it may take you a little longer to get to the solution, you're probably better at inductive and spatial reasoning at middle age than you were in your youth.

The older brain at work

How is it possible for older people to function better even as their brains slow? "The brain begins to compensate by using more of itself," explains Dr. Bruce Yankner, professor of genetics and co-director of the Paul F. Glenn Laboratories for the Biological Mechanisms of Aging at Harvard Medical School. He notes that MRIs taken of a teenager working through a problem show a lot of activity on one side of the prefrontal cortex, the region we use for conscious reasoning. In middle age, the other side of the brain begins to pitch in a little. In seniors, both sides of the brain share the task equally.

The cooperative effort has a payoff. "Several studies suggest that seniors who can activate both sides of the brain actually do better on tasks, while those who can't do worse," Dr. Yankner says.

Compensating for the downsides

If you've found that it's a little harder to carry on a conversation while searching your bag for your keys, MRI studies offer some clues. They show that in younger people, the area of the brain used to do a task goes dark immediately once the task is completed, while in older people it takes longer to shut down. As a result, it's harder for the older brain to take on several tasks, because not only do you need to use more of the brain for any single task, but the brain also has a harder time letting go of a task. So even after you fish out your keys, you may have trouble getting back into the conversation.

What about the moments when you find yourself driving down the street without any recollection of having passed the last few blocks? Or the times you've locked the car door with your keys in the ignition? On those occasions your brain may have slipped into the default mode, which controls processes like remembering and daydreaming that are not required for a directed task. Imaging studies show that interconnected regions of the brain dubbed the "default network" grow more active with age, indicating that as we age we spend more time daydreaming.

  • A simple exercise can help your mind stay focused on the task at hand.

    Make a list. Jot down the times when you've zoned out, forgotten what you were doing, or misplaced something you need. Were you doing something so routine—driving a familiar route or shopping at the supermarket—that you may not have to give it much conscious thought? Were you under stress, like rushing to an appointment?

  • Practice being more aware in similar situations. One way to do this is to describe what you're doing as you do it. For example: "I'm driving through the intersection of State and Elm," or "I'm putting my keys on the hall table." This play-by-play commentary is going to help you remember what you have done.

Getting regular exercise is also important. Physical exercise is the best-documented way to preserve brain function. It helps you to lay down new memories and better focus on the tasks ahead of you. Thirty minutes of moderate exercise on most days is all you need.

What the brain does better with age

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.

One way the older brain is able to repair itself

Dr. Yankner and his research team have discovered that a gene that is switched on during fetal development is reactivated in the brains of healthy older people to repair the effects of stress. The gene, called REST, turns off genes that are responsible for Alzheimer's disease. Autopsies of people who died from Alzheimer's have very little of the REST protein, while people the same age who die of other causes have high levels.

In animal studies, the team found that lithium—a drug that has been used for 50 years to treat bipolar disease—can activate the REST gene. However, because lithium has serious side effects in elderly people at the dose approved for treating bipolar disease, the group is now investigating other drugs that work in a similar way to see if they can activate REST.

Top image: Tissue from a normal aging brain, the REST gene, stained green, is present and active.


Bottom image: Tissue from a brain with Alzheimer's disease, there is very little REST activity.