A neural workout

Last week I wrote about some of the emotional benefits of regular moderate exercise. This week, several timely new articles have come out touting the cognitive advantages of even minimal daily activity. Numerous studies have shown evidence of the neurological benefits of exercise, which can foster cell growth and new cell generation (known as neurogenesis). One region that seems to be particularly impacted is the hippocampus, an area known to be involved in memory consolidation. Prior studies in mice have shown that exercise can trigger neurogenesis in the hippocampus, and in humans exercise has been linked to better performance on memory assessments and spatial learning, as well as a decreased risk for dementia. While some of these benefits are believed to be due to the new proliferation of cells in the hippocampus and other associated regions of the brain, several studies published recently suggest that exercise may serve more as a protective factor against neurological decay than boosting existing memory performance.

study presented last week at the Alzheimer's Association International Conference by doctors at the University of California, San Francisco used mathematical modeling to estimate risk factors for the development of Alzheimer's disease, and came up with seven critical variables: diabetes, hypertension, obesity, smoking, depression, cognitive inactivity, low education, and physical inactivity. Researchers predicted that these seven variables were to blame in nearly 50% of the current cases of Alzheimer's present today, and lack of exercise alone was attributed to over 20% of cases. In addition, researchers predicted that reducing these risk factors could potentially stave off over one million future cases. However, these numbers are theoretical and first author Dr. Deborah Barnes, as well as other lead researchers in the field, are careful to caution against using these numbers as hard goals and guidelines. Barnes notes that while these seven factors do increase the risk for Alzheimer's, a causal relationship has not yet definitively been established, and therefore simply changing one's behavior in regards to one or all of the variables may not be enough to prevent onset of the disease.

While the association between Alzheimer's and exercise is still tentative, there is certainly little doubt about the mental and physical benefits of daily activity. However, previous studies have largely focused on moderate to high levels of exercise in humans and animals, such as the widely recommended guidelines of 30 minutes of exertion 5 days a week. But what about those who cannot get out that much or that often? Fortunately there is new evidence that the cognitive benefits of daily activity can come from even minimal movement, akin to the normal amounts of daily exertion put forth via walking, household chores, and even fidgeting. In a longitudinal study investigating elderly adults aged 70 and up, those with the least amount of daily average energy expenditure had the greatest amounts of cognitive decline over a period of three years, whereas those who were most active had significantly less cognitive impairment both over the three year study period, as well as after a five-year follow-up. It seems that even small efforts such as walking around the block or even moving around the house, which often go unreported in other studies of physical activity, can help stave off the neural deterioration that commonly occurs as we progress into old age.

However, if you still can't be bothered to get up and start moving, you can always resort to surgical implants and get one of these to improve your memory.

Dana Smith

PhD student in Experimental Psychology at the University of Cambridge