Can an active lifestyle help prevent Alzheimer’s?

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

The human need to get rich is not that different. For us, mental stimulation takes many forms, from pursuing higher education or working on a mentally challenging job to reading a book, playing cards, or doing puzzles. The use of our brain helps maintain and increase its sharpness. A classic study published in the journal PNAS in 2000 showed that London taxi drivers, who have to learn to navigate thousands of places in the city, show an enlargement of the brain region responsible for space navigation.

Studies also show that people who frequently engage in mental stimulation activities can preserve their cognitive function and prevent the onset of Alzheimer’s. For example, in a study of a community in Chicago, a score was obtained from older adults for participating in mental stimulation activities using a 5-point scale, with 5 being the most common and 1 the least common. Four years later, those with higher scores were found to be less likely to develop Alzheimer’s. In fact, a one-point increase in activity score was associated with a 64% reduction in disease risk.

When it comes to exercise, cognitive researchers favor aerobic exercises like jogging and cycling over anaerobic exercises like weight lifting. Aerobic exercise can pump the heart, increase blood flow to the brain, increase the supply of oxygen and nutrients, protect neurons from oxidative stress, and fight inflammation. An analysis of 10 studies with 23,000 participants combined found that physically active older adults were 40% less likely to develop Alzheimer’s.

In terms of social engagement, researchers highlight two components: maintaining a sizeable social network of family and friends, and regularly participating in social activities such as clubs, religious services, or volunteer work. Socializing involves talking, listening, and relating to others, mobilizing various regions 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 a lower cognitive decline and a lower risk of dementia.

All of these results come from observational studies that analyze people’s existing lifestyle and cognitive health, rather than providing them with “lifestyle treatment” and then assessing cognitive outcomes. The gold standard of modern medicine is randomized, blinded, placebo-controlled trials, which are more quantifiable and objective, and there have been few trials of such treatments for dementia and Alzheimer’s.

Those that exist have shown disparate results. For example, a study published in the journal Applied Neuropsychology in 2003 found that while mental exercises could train people to do better specific tasks such as remembering words from a list, the effect did not translate into improvement. general cognitive. Clinical trials on social engagement are currently lacking.

One of the reasons why the cognitive benefits of lifestyle enrichment have not been sufficiently studied is that non-pharmacological treatments such as exercise cannot be easily patented, so pharmaceutical companies do not they are interested in investing. It is also difficult to use placebos. In drug trials, participants are assigned a similar sugar pill and a test drug at random, but there is no equivalent to a sugar pill for enrichment activities. In contrast, the control group does not receive any intervention, a fact that cannot be easily hidden to avoid bias, or receives other interventions that may have their own effects and confuse the test results.

In addition, the benefits of enrichment activities may not reproduce well in a laboratory environment. A study published in the journal Neurobiology of Disease in 2009 found that when transgenic Alzheimer’s mice were provided with a treadmill and exercised voluntarily, they experienced more cognitive benefits than if they were placed on a motorized treadmill. and let them run. . The researchers theorized that “mental distress associated with forced running … mitigated the beneficial effects of voluntary exercise.” The same can happen to humans: Running on a treadmill in a lab can have different effects than exercising at home.

In fact, the very nature of enrichment activities contrasts with the philosophy of modern clinical trials. Clinical trials consist of isolating and purifying chemical treatments to evaluate their specific effects. But real-life enrichment activities involve multiple sources of stimulation: attending a math conference or playing cards is mentally appealing, but it can also involve quite a bit of social interaction. Dance and Tai Chi make our body move, but it also forces us to memorize choreographies.

When it comes to cognitive benefits, what we do is less important: reading a book, traveling with friends, learning chess, joining the heart, living your life as if someone left the door open. Isn’t that what we’re supposed to do anyway? If it ends up helping our brains, it’s just the icing on the cake.

-Ms. Yu is a professor of technical and scientific communication at Kansas State University. This essay is adapted from his new book “Mind Thief: The History of Alzheimer’s,” which will be published next month by Columbia University Press.