Advice for keeping memory sharp tends to lean on vague suggestions, do puzzles, eat well, stay engaged. Two controlled studies that measured memory directly, one tracking actual brain volume over a year, one testing recall a week after learning, point to something far more specific, two concrete daily habits with a real, measurable effect on how well memory holds up.
The clearest evidence on the physical brain comes from a 2011 study by Kirk Erickson and colleagues, published in the Proceedings of the National Academy of Sciences. The researchers randomly assigned 120 sedentary older adults to either an aerobic walking program, 40 minutes a day, three days a week, or a stretching and toning control group, and tracked them for a full year. The walking group’s hippocampus, the brain region most central to memory formation, grew by 2.12 percent on the left side and 1.97 percent on the right, effectively reversing one to two years of the volume loss that typically comes with age. The stretching control group, meanwhile, saw their hippocampus shrink by 1.4 percent over the same period, the expected pattern for sedentary older adults. The increases in hippocampal volume in the walking group were directly linked to improved spatial memory performance and to higher levels of a brain protein tied to learning and memory.
A second study helps show that a different kind of daily habit, unrelated to exercise, produces an equally striking effect on how well new information sticks. In a 2008 study by Jeffrey Karpicke and Henry Roediger, published in Science, college students learned 40 foreign-language vocabulary pairs, then were assigned to different study patterns, some kept restudying the material, others kept testing themselves on it. A week later, students who had repeatedly tested themselves recalled about 80 percent of the word pairs, compared to just 33 to 36 percent for students who had spent the same amount of time simply rereading the material. Extra study sessions produced essentially no improvement in long-term retention, while extra testing sessions produced more than a 150 percent improvement. Strikingly, the students themselves couldn’t predict this, their own guesses about how well they’d remember the material hovered around 50 percent no matter which group they were in, completely uncorrelated with what actually happened a week later.
Together, these two studies point to memory as something shaped by specific, repeatable daily actions rather than a fixed trait that simply declines with age. Erickson and colleagues’ research shows that a moderate amount of daily aerobic activity can physically regrow the brain’s memory center within a year, a striking counter to the assumption that hippocampal shrinkage is simply inevitable. Karpicke and Roediger’s research shows that the habit of actively testing oneself on new information, rather than passively rereading it, produces dramatically better retention, even though people have almost no intuitive sense that this is true. Between the two, sharpening memory looks less like a matter of luck or genetics and more like a matter of which specific daily habits a person chooses.
It’s worth being honest about what these two studies don’t establish. Erickson and colleagues’ research involved a relatively small sample of 120 sedentary older adults over one year, and while the hippocampal growth was real and significant, the effect may look somewhat different in younger adults or people who are already physically active. Karpicke and Roediger’s study focused on a specific kind of learning, foreign vocabulary pairs tested a week later, and while the testing effect has been replicated across many other kinds of material since, the exact percentages reflect that particular study’s design.
Within those honest limits, the research offers two concrete, low-cost habits worth building into an ordinary day. A daily 40-minute walk appears to do real, measurable work on the brain’s memory center. Quizzing oneself on new information, rather than simply rereading it, appears to make that information stick dramatically better. Neither requires special equipment or expertise. Both are backed by real, quotable numbers.