I’d always assumed it was true.
Of course your mind starts to go after 40. You start forgetting names and where you left the car keys. By 50, you’re doing crossword puzzles religiously, hoping to keep what’s left of your brain.
That’s how it works, doesn’t it?
The belief that your brain goes downhill as you get older is as old as Plato. Until recently, scientists have focused on finding evidence to support that theory. After all, if they can prove that everyone’s mind goes as they get older, then they’ll get more funding for medical research on the very real scourges of dementia and Alzheimer’s.
But new research is rocking that boat.
Instead of focusing on all the ways in which the aging brain loses ground, some scientists are examining ways in which older brains blast past their youthful counterparts. 
Older people may be smarter than young people. (Something our grandparents wouldn’t have been surprised to hear.)
It all comes down to how you measure intelligence.
Writer and activist Betty Friedan is best known for her 1963 classic The Feminist Mystique. Less known is the fact that, 30 years later, Friedan tackled another hot topic:
The age mystique.
The mysterious belief that we grow more incapacitated, helpless, and childlike as we age.
Science, like all human endeavors, isn’t immune to stereotyping. Aging research is particularly skewed. Results that “proved” cognitive decline with age may not be as valid as previously thought.
Of course older people are going to score worse on tests of intelligence developed for young people, Friedan argues. Their test-taking skills aren’t as fresh as those of 20-year-olds, who’ve spent the last dozen or so years memorizing things.
What really cripples older people in intelligence tests is their refusal to engage in questions on the test designers’ terms. They want context, meaning, explanation, and the option to answer with choices that aren’t on the list.
Does that mean their ability to reason abstractly is impaired … or does it mean they’ve evolved past the need to ace tests?
Friedan is betting on the latter.
It is a developmental advance on the youth’s acceptance of problems at face value, on youthful performance motivated out of compliance with authority and youth’s search for the one ‘correct’ solution.” 
For example, how well do you think you’d do on the SATs if you had to take them again?
If I had to take my SATs tomorrow, I’d never get into college.
My 17-year-old self breezed through standardized testing. But there was a lot she couldn’t do. Like write a book, for example. Writing a book takes a lot more than the ability to reason and remember. You have to feel confident with context, ambiguity, and multiple meanings. I’m a much better author now.
So, was I smarter at 17 than I am today? Surely only a scientist could take that question seriously.
Friedan notes that the bulk of gerontology studies have taken place in nursing homes, among the institutionalized elderly. Of course those folks are going to test poorly on scales of physical and mental health.
As a result of this focus on age-related decline, we overestimate our chances of going senile. Senility affects just 5% of the population. Most healthy adults retain their mental faculties until just before the end of their lives.
One of Friedan’s most frightening conclusions, supported by other age researchers, is that our expectations of age become a self-fulfilling prophecy.
If we think we’re going to become forgetful, lose our ability to learn new things, and perform at lower levels in the workplace, then we’re likely to experience exactly what we expect.
We’ll feel less motivated to challenge ourselves. We’ll choose comfort over growth. We’ll let our children or grandchildren sort out the technology for us rather than learning how to do it ourselves.
Too many older people retire to a life of watching television, doing crossword puzzles, and shuffling around the house. They don’t expect more, and in many cases they don’t want more. They’re quite content with stepping back from the fray of modern life.
But keeping your brain strong until the very end of life requires more than a daily crossword. It requires powerful expectations.
You must believe that your brain can adapt to whatever you throw at it. No matter what you want to do—go back to school, master a language, or learn a new trade—you must believe that age is no impediment.
Your brain is not faulty compared to the brain you had 20 years ago. It’s different. In many ways, it’s better.
Sure, maybe your recall of trivial facts isn’t as strong, but your mind is a mighty tool when applied to other problems, such as social and ethical issues. Your life experience provides invaluable context. You’ve seen the world change over your lifetime. That gives you the kind of perspective that young people, even those raised on a diet of history, can’t hope to understand.
Friedan challenges us to find the freedom and power inherent in age. Reuse to buy into the belief that decline is inevitable. Instead, look forward to further growth. See aging as an adventure with great rewards, including wisdom, serenity, and peace.
In the face of fears surrounding senility and memory loss, a prescription for positive thinking may feel inadequate. But ultimately the brain responds to how we use it.
What we really should be asking ourselves is:
“Am I done with learning for this lifetime … or have I just begun?”
 Betty Friedan, The Fountain of Age (New York: Simon & Schuster, 1993), 108.