Many women over 40 experience some degree of brain lock, such as forgetting why we went upstairs or whom we were just about to phone. And though we may joke about it, we can’t help but wonder if these momentary mental glitches actually mean something dire—maybe early signs of age-related memory loss? And if so, is there anything we can do to keep them from getting worse?
For answers, More turned to John Medina, PhD, director of the Brain Center for Applied Learning Research at Seattle Pacific University, affiliate professor of bioengineering at the University of Washington in Seattle, and author of Brain Rules: 12 Principles for Surviving and Thriving at Work, Home, and School.
Q | Do all human beings lose some brain capacity with age?
A | Most certainly. We all lose about 85,000 neurons a day. We can just kiss them good-bye.
Q | At what age does this decline in brain cells start?
A | We’re probably at our mental peak at 18 or 19 years old, at least for most of the cognitive performances that can be measured in the lab.
Q | What a waste of adulthood!
A | Well, in caveman days, humans didn’t live much past 23 or 24. We lived just long enough to be reproductively competent and to raise kids who could also reproduce. Which is why after age 40, we’re in genetic free fall in terms of aging. Sorry about that.
Q | How does the loss of neurons affect our ability to learn and to remember new information?
A | The effects still aren’t well-documented. But the answer to your question really depends on how we define memory. When a piece of information comes into your head, it goes through four separate processing steps, all of which you could call learning of a sort. The first step is encoding, in which information actually enters your brain through the senses: Light comes into your eyes, sound comes into your ears and so on. The second step is storage; once something gets encoded in your brain, what are you going to do with it? The third is retrieval, which is what most of us think of as memory: being able to get the information out again. Then comes the fourth and, I think, most important step, which is forgetting. Human learning is primarily subtractive. It’s controlled forgetting, learning how to forget in a smart enough way so that you can focus on what’s left in your cognitive landscape.
Q | Do we need to forget because we’re bombarded with so much information all the time?
A | Yes. The brain’s computational speed is pretty slow; it can’t process all the information that’s out there. So it has to make decisions about what it will and won’t take in. Figuring out what’s relevant and irrelevant, and then subtracting the irrelevant, is some of the most important work the human brain can do at any age.
Recently we’ve learned that most midlife memory fading isn’t about memory after all. That is, it’s not about retrieval mechanisms. It turns out that what middle-life brains have a really hard time doing is blocking out unnecessary information. As you get older, you lose your filtering ability.
A good example is not remembering where you put your keys. We sometimes call it a senior moment; it feels like you’ve forgotten something. But what’s actually happening is that lots of other input is flooding into your brain, and you’re unable to turn down that noise so that you can pay attention to the thing you’re trying to remember. As you begin to lose control of controlled forgetting, your ability to attend to things—like where you put your keys—decreases because you can’t prioritize your inputs.
Q | In your book you point out that there are significant genetic and anatomical differences between women’s brains and men’s. Does a woman’s ability to filter out information break down faster than a man’s?
A | No, not at all. Women do have a menopausal issue, and certain aspects of their changing hormone profile can amplify some of the natural effects of aging on the brain. But on the whole, the gender differences in this area are not big. More important, I think, is the fact that women assume responsibility for crucial threads in the social fabric that guys don’t. As a result, women are required to be more reliable. I’m often asked, “Can women multitask?” And the answer is no. Neither can men. The brain cannot multitask. But women often handle a variety of separate tasks during the day: They go to work, pick up the kids and still do most of the housework. It’s difficult enough to juggle all those demands when your brain is young, but as you get older, your brain becomes more easily confused by the scope of your to do list. You may, for instance, forget to pick up milk—or your kids!—on your way home from work.
Q | You also write that under chronic stress, excessive amounts of cortisol can damage the hippocampus, crippling the brain’s ability to learn and remember. What does this mean for women in midlife, who are so often dealing with stressful situations such as raising teenagers, caring for aging parents, adjusting to empty nests—and now, dealing with a severe recession?
A | The type of stress that most harms the brain arises when you feel a lack of control over negative situations, like having a tyrannical boss. It arises when you can’t control when or how often the stressor hits you and when you can’t control its severity once it arrives.
Say, for example, you experience injustice in your workplace. Maybe you were passed over for a promotion that was given to a less qualified man. A woman still earns only 77 cents on every dollar a man earns. So by the time you get to your forties, you’ve been bumping up against the glass ceiling so long you have calluses on your head! The ways in which the workforce still favors men over women can produce the type of stress that’s toxic and which, over time, can become so overwhelming it causes brain damage.
Q | How about some good news concerning memory—is there any?
A | Yes, there is. There are two things that are well-documented in the research literature that can help you control the downward mental spiral of aging. The first is to stop and take an inventory of your life. Pinpoint those areas where you feel overwhelmed and helpless, and try to take command of the situation. If you feel a general frustration in your job, sit down for a talk with your boss. Just making your feelings known can give you a sense of control. If that doesn’t help, then try to transfer to another position.
Specifically, research has shown that when people do feel in control, they can have a negative experience without being stressed. So if your manager bawls you out but you know you’re already going on job interviews, you won’t be as affected as you might have been earlier. It’s the equivalent of holding your hand over a lit stove and saying, “So what?” It’s the perception of lack of control that produces the bad reaction. It’s all psychological.
Q | And what’s the second piece of good news?
A | Let me begin by explaining that there are two different ways people age. The first I call the Mike Wallace style of aging. Wallace just turned 91, and he still has a lion of an intellect. And there’s a whole gigantic population of people who are aging just like him; they’re smart, they’re sophisticated, they retain their cognitive function well into their eighties or beyond. Then there’s a whole other population that is not aging well at all, even in their sixties. So the question was asked almost 20 years ago, “Is there an independent variable that can predict whether you are going to age like Mike Wallace or like that other segment of the population?” And the answer turns out to be yes, there is.
The first piece of data came from geriatric studies done with people over 75. Statistics showed that if you had a physically active lifestyle, your risk of Alzheimer’s was low, your risk for vascular dementia was low and even your risk for affective disorders like depression was low. If you had a sedentary lifestyle, you were debilitated, had heart attacks early and had a much higher risk for Alzheimer’s and other forms of dementia.
Studies also suggest that the ac-tive population is smarter than the sedentary population; that is, people who are active seem better able to “fully mobilize their IQ,” as we say in the lab. Active people score overwhelmingly better in cognitive abilities, spatial reaction times, and a whole range of other things than people who are sedentary.
Q | What, exactly, do you mean by an active lifestyle?
A | Active is defined as the presence of aerobic exercise as a regular part of your life, forever. It’s only been in the past three or four years that we’ve known how important this is. The bot-tom line is, aerobic exercise boosts brainpower, including the ability to pay attention to things and get back your capacity for controlled forgetting. Interestingly, strength-training exercise doesn’t produce this benefit, though it does deliver others.
Q | Can sedentary people increase their brainpower by starting an aerobic exercise program?
A | They sure as heck can! The data show that in as little as four months of exercise—in the lab we use 30-minute aerobic workouts on a treadmill three times a week—it’s not unusual to get a 100 to 200 percent improvement in the various tests that measure the ability to process information. That is, as long as compliance is 100 percent. You won’t get those results exercising once a week.
Q | And will following this routine improve your memory?
A | Yes, but preliminary research suggests memory improves only once you’ve been doing regular aerobic exercise for about three years. So this really is an argument for an immediate lifestyle change.
I actually did this myself last year. I installed a treadmill in my office and built a little platform on it where I could put my laptop. Then I did aerobic exercise five or six times a week, walking on the treadmill whenever I was on e-mail. And it worked! I’ve lost 37 pounds so far, and I’ve never felt intellectually clearer in my life.
JUDY JONES is the coauthor of three editions of An Incomplete Education.