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Mentally stimulating activities may diminish the risk of mild cognitive impairment (MCI) in older people -- even in apolipoprotein E ε4 (APOE4) carriers, researchers found.

In the population-based Mayo Clinic Study of Aging, several activities -- playing games, doing crafts, using the computer, and socializing -- were each associated with a significantly decreased risk of MCI in cognitively normal people age 70 and up over a median follow-up of 4 years, , of the Mayo Clinic in Scottsdale, Ariz., and colleagues

They also found that using a computer and enjoying regular social activities were each tied to a decreased risk of incident MCI in APOE4 carriers.

"Cognitively normal elderly individuals who engage in specific mentally stimulating activities even in late life have a decreased risk of incident MCI," the researchers wrote. "The associations may vary by APOE4 carrier status."

These results "fall into the growing category of studies showing that an enriched social environment has health benefits," said , professor of neurology and epidemiology at Columbia University, who wasn't involved in the study.

Yet Elkind cautioned that since the study is observational, there are unmeasured confounders that make it difficult to draw any conclusions about whether the mentally stimulating activities caused the reduction in cognitive impairment -- or if something else did.

"An alternative explanation is that those who engage in mentally stimulating activity in late life are simply those who have always engaged in such activity, and perhaps were predisposed to do so because of some inherent characteristic that itself put them at reduced risk for later cognitive impairment," Elkind told 番茄社区app. "Or, it may be that those who engage in mental activity are actually engaging in physical activity too, and it is the physical activity that is driving the effect."

For the study, Geda and colleagues assessed 1,929 cognitively normal participants enrolled in the population-based in Olmsted County, Minn., an ongoing study of normal cognitive aging and MCI among persons 70 years or older.

Participants in the study -- which ran from April 2006 to June 2016 -- were followed to the outcome of incident MCI. All were white, the median age at baseline was 77, half were female, the median educational level was 14 years, and 26.7% were APOE4 carriers.

Mentally stimulating activity was defined as reading books, doing crafts such as knitting and quilting, computer use, playing games, and social activities such as going to movies and or to the theater. That activity was surveyed in the year prior to study enrollment, and neurocognition was assessed at baseline and re-evaluated every 15 months.

Over a median follow-up of four years, 456 participants developed new-onset MCI.

The researchers found in adjusted analyses that the following mentally stimulating activities were associated with a diminished risk of incident MCI:

• Playing games (HR 0.78, 95% CI 0.65-0.95)
• Engaging in craft activities (HR 0.72, 95% CI 0.57-0.90)
• Using the computer (HR 0.70, 95% CI 0.57-0.85)
• Social activities (HR 0.77, 95% CI 0.63-0.94)

Analyses by MCI subtype -- amnestic versus non-amnestic -- showed significant associations between a decreased risk of amnestic MCI and craft activities (HR 0.76), computer use (HR 0.75), and social activities (HR 0.74). Only computer use (HR 0.42) was associated with a diminished risk of non-amnestic MCI, but the researchers noted they may have had limited power due to a smaller sample size for non-amnestic MCI.

When assessed by APOE4 genotype, the researchers found that only computer use (HR 0.65, 95% CI 0.46 to 0.92) and social activities (HR 0.62, 95% CI 0.43 to 0.89) were associated with a decreased risk of incident MCI.

"We consistently observed the lowest risk of incident MCI in participants who engaged in any type of mentally stimulating activity and were APOE4 non-carriers compared with the reference group," they wrote. "In contrast, participants who were APOE4 carriers and did not engage in mentally stimulating activities tended to have the highest risk for incident MCI, with the exception of engaging in craft activities."

The researchers acknowledged they couldn't disentangle the reasons why reading didn't appear to have the same impact on decreasing incident MCI risk as computer use, but it may be that a "particular mental activity may require specific technical and manual skills and that these could be the factors that might be associated with a decreased risk of cognitive decline."

Elkind noted that the 14-year median level of education in the study population is "rather high compared to other populations, especially minority populations among whom the risk of dementia is higher."

He said it would be helpful to have more imaging data showing both the structure of the brain -- looking for silent infarcts, for example -- and brain function: "Ideally, the next step would be a randomized clinical trial of some sort among people who are at risk of cognitive decline to see whether those who engage in this activity have better cognitive outcomes."

Still, Elkind said it's important to recognize that more data have shown that mental, social, and physical activities all stimulate and promote brain activity and clinicians should encourage patients of all ages to engage in more "mental flossing."

"Most literature suggests that the benefits of early or mid-life activities are even greater than those of getting active later in life," he told 番茄社区app. "Because of the importance of early-life exposure to stimulation, and its effects on increasing cognitive reserve, it is important to realize that whatever benefits we are seeing in late life would likely be much greater if we could extend these activities to young children, especially those from impoverished backgrounds."

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