Can an active lifestyle help prevent Alzheimer’s disease?

Studies have compared the cognitive performance of mice who live alone in empty cages with those who live in large houses equipped with colorful Lego blocks for mental stimulation, running wheels for exercise, and other mice for mental stimulation. 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 high synaptic activity supported learning. Even mice whose genome was altered to develop the equivalent of Alzheimer’s disease experienced improved brain activity and performed better in maze tests that they had previously failed.

The human need for enrichment is not that different. For us, mental stimulation comes in a variety of forms, ranging from pursuing higher education or work to mentally stimulating work to reading a book, playing cards or 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.

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

When it comes to physical exercise, cognitive researchers favor aerobic exercise such as jogging and cycling over anaerobic exercise such as weight lifting. Aerobic exercise can stimulate our heart, increase blood flow to the brain, increase oxygen and nutrient delivery, protect neurons from oxidative stress, and fight inflammation. An analysis of 10 studies involving 23,000 participants combined found that physically active older people were 40% less likely to develop Alzheimer’s disease.

When it comes to social engagement, the researchers emphasize two things: maintaining a strong social network of family and friends, and regularly participating in social activities such as clubs, church services, or volunteer work. Socialization involves talking, listening, and relating with others, mobilizing multiple 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 people who have a greater 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 lifestyle and cognitive health, instead of providing them with “lifestyle treatment” and then evaluating 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 such trials of lifestyle treatments. for dementia and Alzheimer’s disease.

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 on specific tasks like recalling words from a list, the effect was not translated into overall cognitive improvement. Clinical trials on social engagement are currently lacking.

One of the reasons 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 are not interested in investing. It is also difficult to use placebos. In drug trials, participants are randomly assigned a similar sugar pill and trial drug, but there is no equivalent of a sugar pill for fortification activities. Instead, the control group either receives no intervention, a fact that cannot be easily hidden to avoid bias, or it receives other interventions that may have effects of their own confused trial 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 given a racing wheel and exercised on their own, they experienced more cognitive benefits than if they were placed on a mat. powered and made to run. . The researchers hypothesized that “the mental distress associated with forced running … attenuated the beneficial effects of voluntary exercise.” The same may be true for humans: running on a treadmill in a lab can have different effects than exercise by choice at home.

Indeed, the very nature of enrichment activities is at odds with the philosophy of modern clinical trials. Clinical trials consist of isolating and purifying chemical treatments to assess their specific effects. But real-life enrichment activities involve multiple sources of stimulation: attending a math lecture or playing cards is mentally engaging, but can involve a bit of social interaction as well. Dance and Tai Chi move our body but also force us to memorize the choreography.

When it comes to cognitive benefits, what we do matters less than what we do: reading a book, traveling with friends, learning chess, joining the choir – 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, that’s just the icing on the cake.

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