Why sometimes forgetting is good…and other surprising facts.

For most people over age 40, glitches in memory are high on their lists of health concerns. Whether it’s lost keys, forgotten names or other “senior moments,” we fear each is a sign of a deteriorating brain.

What science now tells us: Memory is not necessarily the most important measure of brain health. And no matter what your age, there are ways to improve the mind. However, many of the popular beliefs about improving mental performance are outdated and incorrect.

Most common myths…

MYTH #1: Brain health steadily declines with age. Scientists used to believe that people were born with all of the neurons (brain cells) that they’d ever have and that the ability to form new brain connections ended in adolescence.

It’s now known that the brain is the most modifiable part of the body. It’s constantly being changed by how we use it, and the changes can be measured within just hours . That’s why you can be confounded by, say, a new cell phone in the morning and then be using it proficiently by the end of the day.

While you are focused on new learning—such as writing an original report or preparing new recipes—neural activity increases and promotes the development of new neurons. But if these neurons are not put to proper use, they die.

As you age, your ability to think more broadly and deeply can continue to grow if your brain is exercised properly—thanks to the functions of your frontal lobes, the part of your brain that sits just behind and above your eyes in your skull. Even though brain health is tied to all parts of the brain, the majority of the heavy lifting is directed through the frontal lobe networks. The frontal lobes are responsible for decision making, judgment, planning and other “executive” functions. (To get an idea of how effectively you’re engaging your frontal lobes in everyday life, see box.)

My advice: Engage your frontal lobes by being curious and creative and by solving problems whenever you can. Challenge your brain by thinking deeply and extracting meaning from information you are given. Example: Think back to a favorite book that you read several years ago, and come up with five to eight different take-home messages that are applicable to different contexts. Better yet: Read it again, and then come up with the list.

MYTH #2: A good memory indicates mental robustness. Surprisingly, memory skills do not correspond to everyday-life performance as much as frontal lobe functioning. This means that you can have an excellent memory but not be very innovative, insightful, creative or mentally productive.

My advice: Don’t worry when you can’t remember everything. Although we tend to note what we forget, we rarely take stock of all the things we do remember.

A brain that gets too occupied with remembering everything works less efficiently and becomes stressed, overwhelmed and bogged down in the details. If something is important in your life—it could be your work, a hobby or even a weekly card game—you’ll remember the details that really matter.

Do not worry about, say, occasional forgotten names or unimportant tasks. But when forgetting regularly interferes with your performance, it may be a sign that something more than benign memory glitches is taking over. Many things can impair memory—not enough sleep, some medications, such as antidepressants and blood pressure drugs, and stress. Memory issues do not always mean Alzheimer’s disease. See your doctor if you’re concerned about your memory.

MYTH #3: Multitasking gives your brain a good workout. Again, not true. When you multitask, the brain has to call on different regions to handle the load. It works inefficiently because the communication isn’t synchronized. When you “overuse” your brain in this way, the frontal lobes become fatigued. This slows efficiency and decreases performance.

My advice: Whatever you’re doing, focus on that and nothing else for at least 15 minutes. Put a “do not disturb” sign on the door. Turn off your phones, and don’t check your e-mail. You’ll think more clearly in those 15 minutes than someone who multitasks for an hour.

MYTH #4: People with a high IQ have the most brainpower. Today’s IQ tests are based on measurements that were developed more than a century ago. They mainly emphasize such skills as knowledge, memory and speed in ability to perform mathematical equations—all of which were much more important in the days before computers and the Internet.

What’s more important is knowing how to use knowledge in novel ways and bringing together facts from disparate areas to create original ideas. As Einstein said, “Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.”

My advice: Whenever you’re confronted with a problem, stop and think deeply about the knowledge you already have. Connecting it and generating original ideas is crucial to brain health.

MYTH #5: Unrelenting mental work boosts brain capacity. It’s true that high achievers can put in long hours and consider lots of information when they try to solve vexing problems. But they also know when to stop looking at more information—and they reach that point earlier than most people do.

Productivity and achievement are not linked to how many hours are worked and how much information is accessed. In fact, decreasing exposure allows your frontal lobes to be deployed to focus on key data, and, even more importantly, to know what information to ignore.

Using knowledge to support a novel approach is essential to enhancing integrated reasoning and deeper-level thinking. Example: Instead of taking copious notes on specific points made in a meeting, boil down the discussion to key issues, new decisions and possibilities.

My advice: Keep your key frontal lobe operations finely tuned by blocking, discarding and ignoring less relevant tasks and information. Consolidating facts and options into big ideas and perspectives is necessary to cultivate creative thinking and problem solving.