Q. Long-term memory obviously has the tightest grip on information. Is there a limit to what our long-term memories can hold?
A. Actually, you can store as much information as you want in your long-term memory—the information that becomes a permanent part of you—without ever exceeding its capacity. It is essentially infinite. That doesn’t mean you can recall everything that you’ve ever learned; sometimes you simply can’t access the memory. People with “good” memories don’t necessarily have more data stored. They are just better at getting to it. The easiest memories to retrieve are often linked to an image or an emotion.
Q. What role does sleep play?
A. For so long we had the wrong idea about sleep, that it is down time, a waste of time. But think of the brain like a tomato. In the day it collects sunlight, goes through photosynthesis and so on. Then the sun goes down and all this restructuring of proteins takes place that allows the tomato to grow. The brain is like that, too. It takes in information while you’re awake, but then it needs to structure and lay that information down.
Q. And that takes a good night’s sleep?
A: It’s best to have at least six hours of sleep between learning activities. So if you take a tennis lesson, don’t take a golf lesson right away—and best of all, take a nap in between. Naps can be as effective as longer sleep for holding on to information. We’ve seen a 16 percent improvement in ability if a person takes a nap after learning a new skill.
Q. What about retirement? Do we lose brain function if we aren’t going through the motions of a job?
A. The ideal retirement, though not possible for many, is gradual. The workplace offers all kinds of challenges, positive and negative, that keep your brain sharp. Socialization is part of it. So when I talk to people about retiring, I ask how happy they are with their work. If they are generally happy, I say they should try to go on a little longer. But if a job is very stressful, then the brain benefits from getting out from under that load.
Q. Where are we with treatments for neuropsychiatric diseases like Alzheimer’s?
A. For the majority, we’ve come up with treatments that can slow the process. If you slow a disease’s process by 30 percent for someone in their 80s, that’s extremely helpful. Importantly, no one is certain when Alzheimer’s actually starts. It may start much earlier than we realize. What some doctors call mild cognitive impairment others see as a precursor to real disease. But it’s also important to know cases can be mild or slow.
Q: Are there actual ways to ward off dementia?
A: Most important, your knowledge base, your intelligence, matters. With Alzheimer’s, we find that more educated patients may have a lot of damage to brain tissue before they begin to show symptoms. It’s like having money in the bank when a financial crisis hits. Building up a strong cognitive reserve helps you withstand the physiological changes in the brain for longer.
Q. How can you tell the difference in loved ones—or yourself—between regular forgetfulness and signs of a real problem?
A. You have to look for real change. If someone is just a little worse than he or she used to be, that’s not as worrisome as a major change in someone who had a super power memory. We all come out of the mall and can’t remember where we parked, probably because when we arrived we were preoccupied with what we were going to buy. But if you come out and can’t remember if you drove or took the bus or someone dropped you off, that’s beyond normal forgetting. That suggests a more serious problem.