The study shows that both physical exercise and mental exercises such as reading books, playing games, and computer use are associated with a lower risk of mild cognitive impairment; a combination of these activities appears to pack a one-two punch that is even more beneficial.
"Our study found that engaging in physical exercise at any frequency, once a week or five times a week, and engaging in mental activities, computer use in particular, appear to have a joint effect in protecting against mild cognitive impairment," says Yonas Geda, MD, of the Mayo Clinic in Rochester, Minn.
Still, the study does not prove cause and effect, cautions Ron Peterson, MD, another Mayo Clinic researcher who worked on the study.
"It could be that people who engage in physical and mental exercise are less likely to show cognitive decline. Or maybe a person with cognitive decline is less likely to exercise and use computers," he tells WebMD.
The only way to know for sure is to follow people who engage in these activities and see if they have less mental decline over time -- a study that others are undertaking, Peterson says.
"Before you embark on such a study, you want to make sure there is a hint it will work, and that is what our study does," he says.
The findings were presented at the annual meeting of the American Academy of Neurology.
Cutting Risk of Cognitive Impairment
The study involved 926 people, ages 70 to 90, participating in the Mayo Clinic Study of Aging. All completed questionnaires asking about physical exercise and cognitive activities during the past year; 817 participants were cognitively normal and 109 had mild cognitive impairment.
Those who were cognitively normal were younger, better educated, less likely to suffer from depression, and had fewer other medical conditions, Geda says.
The results showed that:
- People who engaged in any amount of moderate exercise were 36% less likely to have mild cognitive impairment than people who did not exercise.
- People who engaged in any amount of computer use were 44% less likely to have mild cognitive impairment that people who did not use the computer.
When the researchers took into account other risk factors for mild cognitive impairment, they found that "the beneficial joint effect of moderate physical exercise and computer use was more than what would be predicted from the arithmetic sum of the two," Geda says.
The researchers did not distinguish between different types of computer use.
The findings support other research showing that both physical and mental exercises are good for the brain, says Julie Schneider, MD, of Rush University Medical Center in Chicago, who moderated the session at which the study was presented.
What is new here, she says, is the suggestion that both activities are better than either alone.
Mental Skills: Use Them or Lose Them
A second study presented at the meeting suggests that when it comes to mental skills, use them or lose them.
The researchers looked at cognitive reserve -- "the extra capacity that you have to accomplish tasks mentally," says Bruce Reed, MD, professor of neurology at the University of California at Davis.
"We all have some reserves, some have more than others," he tells WebMD. "They protect us when we get disease or injury."
The study involved about 700 elderly people who had undergone autopsies. The researchers found that the more mind-building exercises such as reading books and playing games that participants did throughout life, the greater their cognitive reserves at death.
Similarly, people with more education had greater cognitive reserve at death, the study shows.
When the researchers looked further, they found that the effect of cognitive activities was more important than education.
"If you have only a high school education and do a lot of cognitive actives throughout life, you'll have greater cognitive reserves. If you have a college education and don’t do anything with it, that predicts lower reserves and less protection against dementia and other injury," Reed tells WebMD.
"This is fascinating work that suggests that it is the cognitively stimulating activities that enhance brain reserve," says David Knopman, MD, a neurologist at the Mayo Clinic.
"The researchers have made a sophisticated attempt at addressing this question, [using] their expertise in mathematical modeling. This approach may be the best we can do for understanding this problem [as there is no] experiment to directly answer the question," Knopman tells WebMD.