Over the long term, regular exercise is correlated with improved cognitive function in later life, a slower decline of that function with aging. This is well established. The work here is interesting for showing that even in the very short term, exercise produces improvements in specific aspects of cognitive function, such as memory. One might add these results to the very long list of good reasons to avoid a sedentary lifestyle. Exercise cannot add a large number of years to life span, and indeed in mice it has no effect on overall life span, but given that it is essentially free and produces highly reliable benefits to health and resilience, slowing and postponing age-related disease, it would be foolish to ignore it.
How quickly do we experience the benefits of exercise? A new study of healthy older adults shows that just one session of exercise increased activation in the brain circuits associated with memory - including the hippocampus - which shrinks with age and is the brain region attacked first in Alzheimer's disease. "While it has been shown that regular exercise can increase the volume of the hippocampus, our study provides new information that acute exercise has the ability to impact this important brain region."
The research team measured the brain activity (using fMRI) of healthy participants ages 55-85 who were asked to perform a memory task that involves identifying famous names and non famous ones. The action of remembering famous names activates a neural network related to semantic memory, which is known to deteriorate over time with memory loss.
This test was conducted 30 minutes after a session of moderately intense exercise (70% of max effort) on an exercise bike and on a separate day after a period of rest. Participants' brain activation while correctly remembering names was significantly greater in four brain cortical regions (including the middle frontal gyrus, inferior temporal gryus, middle temporal gyrus, and fusiform gyrus) after exercise compared to after rest. The increased activation of the hippocampus was also seen on both sides of the brain. "Just like a muscle adapts to repeated use, single sessions of exercise may flex cognitive neural networks in ways that promote adaptations over time and lend to increased network integrity and function and allow more efficient access to memories."