Academic journal article Generations

Healthy Body Equals Healthy Mind

Academic journal article Generations

Healthy Body Equals Healthy Mind

Article excerpt

Adopting a physically active lifestyle early on may be the best way to prevent brain decay.

The number of adults older than sixty-five is expected to increase dramatically as baby boomers age. Unfortunately, this trend is also expected to increase the prevalence of agerelated cognitive impairment and dementia. The costs associated with health and long-term-care services for dementia reached approximately $172 billion in 2010 (Alzheimer's Association, 2010). Such staggering costs demonstrate the need for research to identify effective preventions and treatments for cognitive decline.

Physical activity, such as aerobic exercise, might be both an effective prevention and treatment for late-life brain atrophy and cognitive decline. In contrast to most medications, aerobic exercise interventions are consistently associated with increased cognitive performance and greater brain volume in older adults. Physiologically, aerobic exercise is thought to improve brain health by creating new brain cells, blood vessels, and by enhancing communication between neurons (van Praag et al., 2005; Ding et al., 2006). Newly created vasculature increases blood flow and the transport of nutrients to newly formed cells, resulting in better brain function and increased brain mass.

The studies reviewed in this article used both structural and functional magnetic resonance imaging (fMRI) to examine the effects of exercise on the brain. This method takes advantage of the magnetic properties in brain tissue to create highresolution images. Different tissue types, such as axons that make up white matter, and cell bodies that make up gray matter, resonate at different magnetic frequencies. By sensing these frequencies, the magnetic resonance scanner can create a detailed image of gray and white matter and form snapshots of how the brain functions during cognitively demanding tasks. We can then identify how physical activity influences the integrity of brain circuits in late life.

Three study designs will be reviewed: epidemiological, cross-sectional, and experimental. Epidemiological research examines factors that predict disease risk or mortality at a population level, often sampling hundreds or thousands of individuals. These studies usually follow participants over time (prospectively) or assess relevant data from their past (retrospectively). In contrast, cross-sectional studies sample participant data from a single time-point to assess correlations between variables. Finally, experimental studies manipulate some variable of interest (e.g., an exercise intervention to change fitness levels). After the manipulation, data are sampled to determine whether there are causal relationships between independent and dependent variables.

What Are Normal Brain Changes?

To understand cognitive and physical brain changes that lead to cognitive aging and dementia, first we must understand normal age-related brain changes. The parietal, frontal, and temporal cortices all experience significant tissue loss throughout life. Healthy adults lose approximately 15 percent of their neocortical tissue between ages thirty and ninety, with disproportionately higher losses in areas crucial for executive control (Raz, 2000).

And, healthy adults older than fifty-five experience approximately 1 to 2 percent decline annually in hippocampal volume-an area crucial for forming and recalling memories (Raz et al., 2004). Hippocampal atrophy accelerates in patients experiencing dementia. Decreases in cortical and hippocampal volume often precede and lead to the executive function and memory declines seen in normal aging.

If age-related brain atrophy occurs because of cell shrinkage, death, and loss of vasculature, then exercise is well-suited to rebuild the decaying brain. While it was once thought that the adult brain was incapable of adapting, it is now known that the brain remains relatively plastic throughout life. Neural efficiency, capacity, and flexibility differences result in variations in the ability to withstand damage to the brain's processing system. …

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