Can an active lifestyle help prevent Alzheimer’s?

Studies have compared the cognitive performance of mice living alone in empty cages to mice living in large houses equipped with colorful Lego blocks for mental stimulation, running wheels for exercise, and other mice for social engagement. When mice lived in rich environments, their brains underwent physical changes: more neurons were generated in the brain’s memory center, the hippocampus, and strong synaptic activity supported learning. Even mice whose genomes had been altered to develop the equivalent of Alzheimer’s disease experienced improved brain activity and performed better in maze tests they had previously failed.

The human need for enrichment is not that different. For us, mental stimulation takes many forms, from pursuing higher education or working at a mentally challenging job to reading a book, playing cards or doing puzzles. Using our brain helps maintain and increase sharpness. A classic study published in the journal PNAS in 2000 showed that London taxi drivers, who have to learn how to navigate thousands of locations around the city, show a magnification in the brain area responsible for spatial navigation.

Likewise, studies show that people who often engage in mentally stimulating activities can maintain their cognitive function and prevent the onset of Alzheimer’s disease. For example, in a study from a Chicago community, older adults were scored on how much they participated in mentally stimulating activities using a 5-point scale, with 5 being the most frequent and 1 the least frequent. Four years later, those who scored higher were less likely to develop Alzheimer’s. In fact, a one point increase in the activity score was associated with a 64% reduction in disease risk.

When it comes to exercise, cognitive researchers prefer aerobic exercises such as jogging and cycling to anaerobic exercises such as weight lifting. Aerobic exercise can make our heart beat faster, increase blood flow to the brain, stimulate the supply of oxygen and nutrients, protect neurons from oxidative stress, and fight inflammation. An analysis of 10 studies involving a total of 23,000 participants found that physically active older adults were 40% less likely to develop Alzheimer’s disease.

In terms of social engagement, researchers emphasize two components: maintaining a large social network of family and friends and participating regularly in social activities such as clubs, religious services or volunteering. Socializing involves talking, listening, and interacting with others, mobilizing various areas of the brain that also support memory and other cognitive activities. Social support also reduces stress, which in turn can improve cognitive function. Studies show that older adults who have a larger social network and participate in more social activities have less cognitive decline and a lower risk of dementia.

All of these findings come from observational studies that look at people’s existing lifestyles and cognitive health, rather than giving them a “lifestyle treatment” and then assessing cognitive results. The gold standard in modern medicine is randomized, blind, placebo-controlled trials, which are more measurable and objective, and there have been few such studies of lifestyle treatments for dementia and Alzheimer’s disease.

The ones out there have shown varying results. A study published in 2003 in the journal Applied Neuropsychology found that while mental exercise could train people to do better at specific tasks, such as memorizing words from a list, the effect didn’t translate into overall cognitive improvement. Clinical studies of social engagement are currently lacking.

One reason the cognitive benefits of lifestyle enrichment have not been studied enough is that non-pharmacological treatments such as exercise cannot be easily patented, so pharmaceutical companies are not interested in investment. It is also difficult to use placebos. In drug trials, a similar sugar pill and a test drug are randomly assigned to participants, but there is no equivalent of a sugar pill for fortification activities. Instead, the control group is either given no intervention, a fact that cannot be easily hidden to avoid bias, or they are given a number of other interventions that can affect their own and confusing study results.

In addition, the benefits of enrichment activities cannot propagate well in a laboratory setting. A study published in the journal Neurobiology of Disease in 2009 found that when transgenic Alzheimer’s mice were given a running wheel and exercised of their own free will, they experienced more cognitive benefits than when they were put on a motor-powered treadmill and made to run. . The researchers theorized that “mental stress associated with forced running … mitigated the beneficial effects of voluntary exercise.” The same can be true for humans: running on a treadmill in a lab can have different effects than exercising at home at will.

Indeed, the nature of enrichment activities is contrary to the philosophy of modern clinical research. Clinical trials are about isolating and purifying chemical treatments to assess their specific effects. But real life enrichment activities bring multiple sources of stimulation: attending a math class or playing cards is mentally engaging, but can also involve a fair amount of social interaction. Dancing and Tai Chi move our bodies, but also require that we memorize choreography.

When it comes to cognitive benefits, what we do is less important than what we do: read a book, travel with friends, play chess, join the choir – live your life as if someone left the gate open. Isn’t that what we should be doing? If it helps our brains, that’s just the icing on the cake.

-Mrs. Yu is a professor of technical and scientific communication at Kansas State University. This essay is an adaptation of her new book “Mind Thief: The Story of Alzheimer’s,” which will be published next month by Columbia University Press.