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The hours you spend tracing countries on a globe or puzzling over a chessboard may add up to more than idle time. According to a new study, such mentally stimulating pursuits are linked to years-long delays in Alzheimer's disease and mild cognitive impairment.
Published this month in Neurology, the journal of the American Academy of Neurology, the study is among the largest of its kind, following 1,939 adults with an average age of 80 and tracing their cognitive trajectories alongside a lifetime of reported activities stretching back to childhood.
The contrast between the most and least cognitively enriched participants was stark. Those in the top 10 percent developed Alzheimer's at an average age of 94; those in the bottom 10 percent, at 88. Mild cognitive impairment showed a similar split: 85 in the highest group, 78 in the lowest.
Five years' difference for Alzheimer's. Seven for mild cognitive impairment.
"I was positively surprised," Andrea Zammit, a study co-author and an assistant professor of psychiatry and behavioral sciences at Rush University Medical Center in Chicago, said.
The results lend new momentum to a provocative proposition: that the texture of daily life - what we practice, whom we see, how we fill an idle hour - may leave a measurable imprint on the aging brain.
Last year, an analysis of roughly 10,000 people found that those who regularly listen to music or played an instrument are less likely to experience cognitive decline. Another study found that people who dance more than once a week had a 76 percent lower risk of dementia compared with those who rarely dance. Other researchers have identified a quieter hazard: loneliness, now linked to a heightened risk of dementia, prompting experts to emphasize the importance of sustaining social ties.
Timothy Hohman, a professor of neurology at the Vanderbilt Memory and Alzheimer's Center, said the study's findings - that cognitive enrichment as early as age 6 may still echo eight decades later - are "mind-blowing."
"What they show is that your cognitive engagement at certain times in your life course have big effects on your late-life cognitive performance," Hohman said.
The findings nod to the concept of "cognitive reserve"- the idea, popularized by Columbia University neuropsychologist Yaakov Stern, that the brain can adapt to damage or aging by relying on alternative networks or strategies. The theory is that mentally demanding activities over a lifetime may strengthen neural connections, giving the brain more flexibility to compensate.
Stern, who was not involved in the new study, said he was particularly struck by its inclusion of a large number of brain autopsies - nearly 1,000. Even when participants had similar levels of damage in their brains - including amyloid plaques and tau tangles that can accumulate decades before Alzheimer's symptoms become noticeable - those who had led more enriched lives were cognitively superior as measured by tests.
"This is a hopeful message," Stern said. He said this type of work may one day "help us understand why the brain is working better for some people than others."
For their analysis, Zammit and her colleagues broke life into three stages and calculated enrichment scores for each participant based on their self-reported surveys.
Those stages and some related participant activities are:
• Early life (before age 18): Being read to and reading books; access to newspapers, atlases and globes in the home; and learning a foreign language for more than five years.
• Midlife: Reading and writing; having household resources like magazine subscriptions, dictionaries and library cards; visiting a museum.
• Late life (around age 80 and older): Doing crossword puzzles, playing games such as chess and checkers.
The participants, mostly residents of northeastern Illinois near Chicago who volunteered to be part of the Rush Memory and Aging Project, were recruited from retirement facilities, care homes and other community settings, and were followed for an average of eight years. The study stops short of proving that having what Zammit calls an "active" or "busy" mind prevents Alzheimer's; it identifies a relationship, not a cause.
None of the participants had dementia when the study began, but 551 subsequently developed Alzheimer's and 719 mild cognitive impairment. Overall, in adjusting for age, sex and education, people with the higher scores in lifetime enrichment had a 38 percent lower risk of Alzheimer's and a 36 percent lower risk of mild cognitive impairment.
Many of the activities examined in the study require time, access or money - advantages that not everyone has. Higher socioeconomic status itself was linked to some protection. But Zammit said the effects of cognitive enrichment were even stronger, which is encouraging because those behaviors - like reading, learning new skills or staying socially engaged - are choices people may be able to incorporate into their daily lives, regardless of background.
Some of the activities examined in the study might seem old-fashioned - the participants, after all, grew up in a different time. But Zammit said the underlying principle isn't tethered to any one generation. The tools may have changed in the digital age; the importance for keeping your mind busy has not.
"As long as you are constantly scouring for knowledge and looking to learn, that's what we see as important here," she said.