The key to staying sharp in old age is to exercise your brain throughout life. Now the latest research shows that such activity may actually slow cognitive decline and, if you do develop dementia, shorten the time you spend living with it.
The new study, which was published in Neurology, involved
nearly 300 older people, about half of whom developed dementia or mild cognitive impairment (often a precursor to dementia), over the course of six years. At the start of the study, participants reported on how frequently they engaged in mentally stimulating experiences throughout life such as extracurricular activities while in school and, more generally, reading books, writing letters, reading the newspaper and visiting libraries. (Because the research started over 20 years ago, internet related activity was not common.)
By studying brain autopsies after the participants died, the scientists found that 14% of the variability in mental decline could be attributed to the amount of intellectual activity in which people participated, both early and late in life. And that effect was seen even after the researchers accounted for other factors that influence dementia like age and education.
They also adjusted for the effect of brain changes due to diseases such as Alzheimer’s, stroke and Parkinson’s disease, which the research team said accounted for about a third of the differences in people’s cognitive decline before death. By comparison, cognitive activity accounted for nearly half as much as such pathology.
The people who were most active in late life showed a 32% slower rate of decline compared to those who maintained an average level of mental activity. And those who were the least active had a 48% faster fall into dementia.
“The beauty of this study is that they tested people at different points and followed them [through to] autopsy,” says Prashanthi Vemuri, an Alzheimer’s researcher at the Mayo Clinic who wrote an editorial accompanying the study, but was not otherwise associated with the trial. “People need to know [this] and be aware that it is possible to slow down the decline of dementia,” Vemuri says.
That’s important knowledge, given that nearly half of people over age 85 develop Alzheimer’s and the baby boom generation is rapidly approaching the age at which risk starts to increase; the lifetime risk of Alzheimer’s for women is 17% and for men is one in ten. By 2050, the Alzheimer’s Association estimates that the prevalence of dementia will double due to the increased proportion of the elderly in the population.
“Anything having to do with reading and writing counts in spades,” says the study’s lead author Robert Wilson, senior neuropsychologist at the Rush Alzheimer’s Disease Center at Rush University in Chicago. Sending emails or reading news online, he suspects, would have similar effects. “There’s no reason to think they wouldn’t be as mentally stimulating.”
How early does the mental activity have to start? Earlier research found that childhood intelligence can account for some of the differences in the brain once attributed to later-life cognitive activity. But whether it does so by increasing lifetime cognitive activity— people who grow up reading, for example, tend to be life time learners— or through some other means is not clear. The new study found that both early childhood cognitive activity and such activity in middle age were linked with slowing mental decline.
Vemuri says brain aging is similar to having money in the bank— people who are intelligent are cognitively “richer” and therefore have more reserves upon which to draw when brain function starts to decline. Consequently, it takes longer to “bankrupt” these resources. And cognitive activity throughout a lifetime can increase this “wealth.” But this study shows that greater cognitive activity not only adds funds, but actually slows the rate at which you lose intellectual resources— and that helps no matter how much you start out with.
Research also shows that engaging in more intellectual activity shortens the time during which someone is actually demented if they do get ill— meaning that it not only delays active disease, but shortens the worst part of it. “Reading, writing playing music, playing games [all of these] could be good,” says Vemuri, “I don’t want to pinpoint specific activities: keeping your brain mentally stimulated and active is what is primary.”
And it’s not just intellectual stimulation that may be important. Social engagement also seems to be crucial. “We’re finding in our studies that social interactions and group activities seem to help,” she says.
“The more, the better,” Wilson says. “But it’s not like physical exercise, [where it’s] ‘no pain, no gain.’ The metaphor should be ‘a hobby.’ In order to change structure and function, the activity needs to be sustained and to be sustained, it needs to be enjoyable. Hobbies like quilting or photography, acting and theatre, book clubs: those sorts of things. There’s no product that needs to be bought and one size won’t fit all.” What is important, he says, is that the activity is intellectually stimulating, and interesting enough to keep you occupied for more than one or two sessions.