Exercise for your brain
A common fear among older adults is that our bodies will outlast our brains, that even if we do not experience dementia in our 60s or 70s, we almost certainly will if we live into our 80s and beyond.
A big part of the solution is to go to the gym, go for a walk, ride a bike or get on cross-country skis.
Dementia occurs when neurons in the brain quit working properly, lose connections with other neurons and die. Statistics support our fears about it: Half of people 85 and older may have some form of it, though severity varies widely.
We spend billions searching for ways to prevent and cure Alzheimer’s and other causes of dementia, with most of the research focused on drugs to block physiological processes that occur with neuron death and to increase levels of neurotransmitters. But a leading neuroscientist, Michael Merzenich, says that these drugs, at best, result in four to six months of improvement. More importantly, they do not address what our brains really need to maintain normal function.
We know that physical exercise can keep our bodies young — or at least younger — well into old age, and research into the effects of physical activity on brain health has increased over the last few decades. In fact, being physically active appears to be one of the best ways to reduce our chances of dementia, even if we are genetically prone to it.
The brain, which accounts for only 2 percent of body mass in humans, uses 20 percent of our oxygen, so earlier research on exercise and brain health focused on aerobic fitness. Aerobically fit people exhibit healthier vascular structures throughout their bodies, and better vascular networks result in optimal nourishment of oxygen-hungry brain cells.
Improved blood flow can improve brain health at any age, and older people who remain — or become — aerobically fit reduce their risk for cardiovascular disease and diabetes, two chronic ailments that deteriorate the brain as well as the rest of the body. They also experience fewer “little strokes” that can chip away at cognitive function.
While it is easier to establish the physical activity habit when we are young, one of the more exciting findings from this line of research is that moderate or vigorous physical activity three or more days per week can improve brain function even among people who start later in life.
Science used to be certain that the brain’s ability to change and rewire itself — called neuroplasticity — ended in young adulthood. But proof to the contrary has exploded in recent years, and physical activity is one of the best ways to preserve and improve that ability.
Exercise increases the production of brain-derived neurotrophic factor (BDNF), a key protein active in higher order thinking processes. BDNF also helps our brains maintain healthy neurons and create new ones, critical to preventing diseases such as Alzheimer’s and Parkinson’s.
More physically fit people have higher brain volume, particularly in the frontal cortex, which, like the hippocampus, appears capable of creating new neurons. And new neurons improve the number and viability of capillaries throughout the brain.
Moderate to vigorous physical activity can help even if heredity deals us a bad hand. A recent Cleveland Clinic study assessed the expression of apolipoprotein-E 4 (apo-E4) among 97 participants age 65-89 over an 18-month period. Apo-E 4 is a true bad guy, the strongest known genetic risk factor for Alzheimer’s.
Researchers grouped the participants according to physical activity level: low activity was slow walking or other low-intensity activity two or fewer days per week; high activity was moderate or vigorous activity, such as brisk walking or swimming, three or more days per week. Both groups had participants with lower and higher risk for Alzheimer’s — as measured by apo-E 4 — but all were cognitively normal at the outset.
Since the hippocampus, a brain structure essential to learning and memory, shrinks as Alzheimer’s disease progresses, the Cleveland Clinic researchers measured its size in the study participants at the beginning and end of the 18 months. They found a 3 percent decrease in hippocampal size among those with a high genetic risk and low physical activity. As expected, the size of the hippocampus was stable in those with low genetic risk, but it was also stable in participants who had high genetic risk and high physical activity.
Clearly, challenging ourselves mentally is vital to healthy aging. Our brains thrive on novelty, so acquiring new skills (i.e. learning a new language or musical instrument) preserves overall function.
According to many brain researchers, activities that combine focused concentration with physical exercise are among the best ways to preserve cognitive function as we age. Because dancing is a particularly effective example, my marathon-running husband is out of excuses.
Angelyn Frankenberg is a wellness coach and writer living in Carbondale. She has a master’s in physical education and an undergraduate degree in music.
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