Can an active lifestyle help prevent Alzheimer’s disease?

The studies 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 involvement. When mice lived in rich environments, their brains underwent physical changes: more neurons were generated in the memory center of the brain, the hippocampus, and strong synaptic activity supported learning. Even mice that had the genome modified to develop the equivalent of Alzheimer’s experienced improved brain activity and performed better on maze tests that they previously rejected.

The human need for enrichment is not so 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 puzzles. Using our brain helps maintain and increase its clarity. A classic study published in the journal PNAS in 2000 showed that taxi drivers in London, who have to learn to navigate thousands of locations in the city, show an expansion in the brain region responsible for space navigation.

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

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

In terms of social engagement, researchers emphasize two components: maintaining a sizeable social network of family and friends and regular participation in social activities such as clubs, religious services or volunteer work. Socialization involves speaking, listening and relating to others, mobilizing several regions of the brain that also support memory and other cognitive activities. Social support also reduces stress, which in turn can increase 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 findings come from observational studies of people’s existing lifestyles and cognitive health, as opposed to providing them with “lifestyle treatment” and then assessing cognitive outcomes. The gold standard in modern medicine is randomized, blinded, placebo-controlled studies, which are more quantifiable and more objective, and there have been few such studies on lifestyle 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 exercise could train people to do specific tasks better, such as remembering words from a list, the effect did not translate into overall cognitive improvement. Clinical trials on social involvement 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 are not interested in investing. It is also difficult to use placebos. In drug studies, a similar sugar pill and a test drug are randomly assigned to participants, but there is no equivalent of a sugar pill for enrichment activities. Instead, the control group either does not receive any intervention, which cannot be easily hidden to avoid bias, or they receive other interventions that may have their own effects and confuse the results of the studies.

Moreover, 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 treadmill and exercised of their own free will, they experienced more cognitive benefits than if they were put on a motorized treadmill and made to run. . The researchers theorized that “mental suffering associated with forced running … attenuated the beneficial effects of voluntary exercise.” The same can be said for human beings: running on a treadmill in a laboratory can have different effects than exercise at home.

Indeed, the very nature of enrichment activities is in contradiction with the philosophy of modern clinical trials. Clinical trials aim to isolate and purify chemical treatments to assess their specific effects. But real-life enrichment activities involve several sources of stimulation: Attending a math lecture or playing cards is mentally engaging, but can also involve social interaction. Dance and Tai Chi set our bodies in motion, but they also force us to memorize the choreography.

When it comes to cognitive benefits, what we do matters less than we do: we read a book, travel with friends, learn chess, join the choir – live your life as if someone were leaving the door open. Don’t we have to do this anyway? If it helps our brain, it’s just the icing on the cake.

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