In the study, which was published in the Journal of Alzheimer’s Disease, researchers looked at the effects of exercise, specifically walking, on the brain function of a group of adults with mild cognitive impairment (MCI).
People with MCI experience cognitive changes that are serious enough to be noticed but are not severe enough to interfere with daily life. Amnestic MCI primarily affects the memory, while non-amnestic MCI mostly affects thinking skills. MCI affects up to 20 percent of elderly Americans. While the cause of MCI remains uncertain, evidence suggests that it increases the risk of Alzheimer's disease and other forms of dementia. Estimates show that the economic costs caused by dementia grow at a rate of 15.94 percent annually, up from $279·6 billion in 2000 to $948 billion in 2016. Europe and North America bear the highest dementia-related economic burden globally.
The study observed 17 adults with MCI and 18 healthy adults who functioned as control; all of them were between the ages of 61 and 88. The exercise intervention lasted 12 weeks and included four 30-minute sessions of moderate intensity walks on the treadmill per week. Exercise intensity was progressively increased over the first four weeks. The participants also engaged in 10 minutes of light activity as warm-up and cool-down. The treadmill speed and grade were gradually increased per session to promote increases in aerobic fitness. It focused on changes in cerebral blood flow in specific brain regions that are known to be involved in the development of Alzheimer's disease. These are parts of the brain that affect perception, motor control, self-awareness, cognitive functioning, decision-making, anticipation, impulse control, emotion, language processing, and speech.
The researchers noted that among the group with MCI, there was a decrease in cerebral blood flow that occurred along with a notable increase in their cognitive tests. This was a significant observation because it is elevated blood flow, not reduced, that is usually thought to benefit the brain. Dr. Carson Smith, an associate professor at the University of Maryland, explained that when an adult begins to experience subtle memory loss, the brain goes on "crisis mode." The brain may then try to compensate for the inability to function at its peak by increasing cerebral blood flow. The results of the study suggest that exercise has the potential to reduce this compensatory blood flow, potentially preventing or postponing the onset of dementia. Decreased cerebral blood flow in the MCI group was also linked to improved verbal fluency.
Unlike the group with MCI, the control group exhibited increased cerebral blood flow after 12 weeks. The cognitive tests of the control group also showed improvement. While the participants of the study all showed fitness and cognitive improvements, the researchers do not yet know how long these changes will last, or what exercise program is necessary to sustain them. The results remain promising, however, because they showed improved brain function even for patients already experiencing cognitive decline. (Related: Physical exercise reduces severity of Alzheimer's symptoms.)
A decline in memory and other thinking skills is a frightening condition that currently does not have a known, specific cure. Yet, studies have already shown that physical fitness reduces the risk of dementia. The study by Smith and his team is a good addition to the growing number of studies that link exercise with cognitive health and may help arrest the increase in people living with dementia.
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