Physical fitness may be crucial for staying youthful as we age, according to a new study of brain activation patterns in older people.
For most people, flexibility and efficiency decline after 40 years old. We do not multitask as well and our mental processing has less clarity.
Recently, neuroscientists have begun to quantify how those cognitive changes play out in our brains. In studies comparing brain activation in young people with that of people past 40, they have found notable differences, especially during mental tasks that require attention, problem solving, decision-making and other types of high-level thinking.
Such thinking primarily involves activation of the brain’s prefrontal cortex.
In young people, activation in the cortex during these cognitive tasks tends to be highly localized. Depending on the type of thinking, young people’s brains light up almost exclusively in either the right or left portion of the prefrontal cortex.
But in older people, studies show, brain activity during the same mental tasks requires far more brainpower. They typically display activity in both hemispheres of their prefrontal cortex.
In effect, they require more of their brains’ resources to complete the same tasks that young people do with less cognitive effort. There’s a general reorganization and weakening of the brain’s function with age.
But scientists did not know if this process could be slowed down or prevented altogether.
Hideaki Soya, a professor of exercise and neuroendocrinology at the University of Tsukuba in Japan, studies the effects of exercise on the brain, and decided to take a further look into this study.
For the new study, which will appear next month in NeuroImage, Dr. Soya and his colleagues used 60 Japanese men between the ages of 64 and 75 who showed no signs of dementia or other serious cognitive decline.
They tested each man’s aerobic fitness in the laboratory.
Then on another day, they fitted each volunteer with a series of tiny probes across their foreheads and scalps. The probes used infrared light to highlight blood flow and oxygen uptake in various parts of the brain.
With the probes in place, the volunteers completed complex, computerized tests, during which names of colors appeared in type of a different color. The word blue would appear in yellow type, for instance, and the volunteers would be expected to press keys corresponding to the name, but not the hue, of the word.
This test makes considerable demands on someone’s attention and decision-making and, in young people, has been shown to dramatically light up the left hemisphere of the prefrontal cortex.
But when the scientists examined the brain activity of these older men, they found that most also required activity in their right hemispheres. They needed more of their brains to pitch in in order to complete the task, displaying the tendency of weakening brain function with age.
However, the most aerobically fit of the subjects did not follow this tendency. The fittest men showed little or no activation in their right hemispheres; they needed only their left hemisphere for the task.
In terms of attention and rapid decision-making, their brains worked like those of much younger people. They also were quicker and more accurate in their keystrokes, indicating that they attended and responded better than the less-fit volunteers.
The importance of this study is that the results showed that daily mild exercise such as walking and mild jogging may affect the way the brain works, so that an older person’s brain acts younger than it is.