Forget everything you’ve heard about mental decline starting in your thirties. A new study suggests your brain may keep getting sharper well into your forties, allowing for a much higher cognitive skill peak, but only if you keep it engaged.
Researchers from Stanford and the University of Cambridge followed thousands of German adults over several years. They tracked how each individual’s literacy and numeracy skills changed. However, instead of comparing different age groups all at once—a method that often confuses generational differences with aging—they looked at how the same individuals’ abilities evolved over the years.
This gave them a much clearer window into how our cognitive skills really shift as we grow older. So when do human cognitive skills peak? Well, according to the data, literacy and numeracy both continue to improve into the early forties.
Literacy then levels off and stays fairly strong, while numeracy starts to dip some. But even that decline isn’t universal. Adults who use reading and math skills regularly—at work or in everyday life—can maintain or even improve their cognitive skills well into their fifties.
This study disproves a longstanding belief that mental decline is inevitable. In fact, how often you use your cognitive skills plays a bigger role in when they peak than age alone does. The more engaged your brain is—reading, problem-solving, etc—the longer you can delay or avoid any decline.
Obviously, there are other factors to take into account here—like cognitive diseases, including Alzheimer’s—but it’s nice to know that we aren’t all relegated to a life of slow cognitive decline just for existing. Having a better understanding of when our cognitive skills are important, especially as more jobs demand complex thinking and adaptability—something our use of AI may be affecting as well.
But this research also shows that the peak isn’t a hard limit—it’s a potential you can stretch by staying mentally active. In fact, it’s best to think of your brain as a muscle that grows stronger with use and weaker when you neglect it.
So, if you’re in your thirties, forties, or even beyond, this new research suggests you may not have hit your cognitive skill peak just yet. Keep challenging your mind with puzzles, video games, and other avenues of learning. Who knows, your best thinking years might still be ahead of you.
