Physical fitness is known to ease the process of aging. A new study from Japan’s University of Tsukuba has revealed that there is a direct link between brain activity and mental and physical performance. In the study, older adults who had higher levels of physical fitness responded the fastest when completing a cognitive task.
The study’s hypothesis is based on previous research regarding the differences in brain function between older and younger people. In young people, the brain’s prefrontal cortex (PFC) mostly processes tasks related to short-term memory, words, and recognizing familiar objects in left side of the brain. In contrast, older adults tend to do more processing in the right side of the PFC and, in fact, make use of both sides of the PFC. The brain becomes less efficient with age. This shift from the left to the right side reflects the brain’s efforts to reorganize itself to become more efficient.
To test how physical fitness impacted right-side and left-side processing in the PFC, the researchers conducted fitness and cognitive tests with 60 men, aged 64 to 75 years. The men completed an aerobic fitness test, in which the participants demonstrated wide variance in fitness levels. The researchers measured attention and reaction time using the Stroop test. The Stroop test involves responding to colors and words for colors. The respondents were asked to say what color a word was (for example, green) instead of what color the word named (for example, blue). During the test, the researchers also measured brain activity using a type of neuroimaging called functional near-infrared spectroscopy (fNIRS).
All the participants demonstrated activity in both sides of the prefrontal cortex during the Stroop test, but there were some differences between fitter and less fit participants. Men whose brain activity favored the left side while responding to the Stroop test had faster reaction times. This suggests that older adults whose brain activity makes use of the left-side PFC have better cognitive function. The fNIRS data revealed that the fitter men also had shorter reaction times and more youthful brain patterns than their less-fit peers.
Lead study author Dr. Hideaki Soya explains what might cause this effect. “One possible explanation suggested by the research is that the volume and integrity of the white matter in the part of the brain that links the two sides declines with age. There is some evidence to support the theory that fitter adults are able to better maintain this white matter than less fit adults, but further study is needed to confirm this theory.”
This research is published in the journal NeuroImage.
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