Can an active lifestyle help to ward off Alzheimer’s?

Studies have compared the cognitive performance of rats living alone in empty cages with those living in large houses equipped with colorful Lego blocks for mental stimulation, exercise racing wheels and other rats for social involvement. When rats 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 that had their genomes altered to develop the equivalent of Alzheimer’s experienced increased brain activity and did better in labyrinth tests that they had previously failed.

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 solving puzzles. Using our brain helps to maintain and increase its sharpness. A classic study published in PNAS magazine in 2000 showed that London taxi drivers, who must learn to navigate thousands of points in the city, have an enlargement of the brain region responsible for space navigation.

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

When it comes to physical exercise, cognitive researchers prefer aerobic exercise, such as running and cycling, rather than anaerobic exercise, such as weight lifting. Aerobic exercise can make our hearts pump, 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 elderly people were 40% less likely to develop Alzheimer’s.

As for social engagement, the researchers emphasize two components: maintaining a considerable social network of family and friends and participating regularly in social activities such as clubs, religious services or volunteer work. Socializing involves talking, listening and relating to other people, mobilizing various regions of the brain that also support memory and other cognitive activities. Social support also reduces stress, which can, in turn, improve cognitive function. Studies show that elderly people who have a larger social network and participate in more social activities have less cognitive decline and less risk of dementia.

All of these findings come from observational studies that examine people’s existing lifestyle and cognitive health, rather than 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 objective, and there are few studies of this type of lifestyle treatment for dementia and Alzheimer’s.

Those that exist have shown mixed 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, such as remembering words on a list, the effect did not translate into general cognitive improvement. Currently, clinical trials on social engagement are lacking.

One reason the cognitive benefits of lifestyle enrichment have not been sufficiently studied is that non-pharmacological treatments, such as physical exercise, cannot be easily patented, so pharmaceutical companies are not interested in investing. It is also difficult to use placebos. In drug testing, a similar sugar pill and a test drug are randomly assigned to participants, but there is no equivalent to a sugar pill for enrichment activities. Instead, the control group does not receive intervention, a fact that cannot be easily hidden to avoid prejudice, or it receives some other interventions that can have effects on its own and confuse the test results.

In addition, the benefits of enrichment activities may not reproduce well in a laboratory setting. A study published in the journal Neurobiology of Disease in 2009 found that when transgenic mice with Alzheimer’s were given a running wheel and exercised on their own, they experienced more cognitive benefits than if they were placed on a motorized treadmill and made to run. The researchers theorized that “the mental suffering associated with forced running … mitigated the beneficial effects of voluntary exercise”. The same may be true for humans: running on a treadmill in a laboratory can have different effects than exercising by choice at home.

In fact, the very nature of enrichment activities is at odds with the philosophy of modern clinical trials. Clinical trials try to isolate and purify chemical treatments to assess their specific effects. But real life enrichment activities involve several sources of stimulation: Attending a math class or playing cards is mentally engaging, but it can also involve a lot of social interaction. Dance and tai chi move our bodies, but they also require 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 – live your life as if someone has left the gate open. Isn’t that what we should be doing anyway? If it ends up helping our brain, it’s just icing on the cake.

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