Exercise Activates Memory Neural Networks In Older Adults

A study of cognitively healthy older adults showed that just one session of moderately intense exercise increased activation in the brain circuits associated with memory. The regions of the brain that were activated by exercise included the hippocampus, which shrinks with age and is associated with cognitive impairment, such as Alzheimer’s disease.

These findings were reported in “Semantic Memory Activation After Acute Exercise in Healthy Older Adults” by Junyeon Won, Alfonso J. Alfini, Lauren R. Weiss, Corey S. Michelson, Daniel D. Callow, Sushant M. Ranadive, Rodolphe J. Gentili, and J. Carson Smith. The researchers sought to determine how moderately intense aerobic exercise affected memory performance. A growing body of research suggests that regular participation in aerobic exercise is associated with enhanced cognitive function. However, less is known about the beneficial effects of acute exercise on semantic memory; semantic memory involves the capacity to recall words, concepts, or numbers. This study investigated brain activation during a semantic memory task after a single session of exercise in healthy older adults using functional magnetic resonance imaging (fMRI).

The study examined the mental performance of 32 physically active, right-handed older adults ages 55 to 85 years old. Potential participants were excluded if they reported a history of stroke, diabetes, high blood pressure, neurological disease, major psychiatric disturbance, substance abuse, or were taking psychoactive prescription medications. Participants were pre-screened using a structured interview questionnaire which included items pertaining to MRI safety to ensure they could participate in the MRI scan. Before the first MRI scan, participants completed a seven-day physical activity recall (PAR). PAR is a semi-structured interview that estimates an individual’s time spent in physical activity, strength, and flexibility activities for the seven days prior to the interview. The participants also completed the Mini-Mental State Examination (MMSE), a 30-point questionnaire used to screen for global cognitive impairment and dementia; their mean scores were 29.3 out of 30, indicating that the participants were cognitively normal. The participants then underwent two experimental visits on separate days. During each visit, the participants engaged in 30 minutes of rest or stationary cycling exercise immediately before performing a Famous and Non-Famous name discrimination task (FNT) during fMRI scanning. The fMRI task stimuli consisted of 30 names of easily recognizable prominent entertainers, politicians, or sports figures obtained from magazines, trivia books, and the Internet and 30 names of non-famous individuals chosen from a local phone book. For this task, the participants used a clicker to categorize the names as famous or not famous. The researchers assessed accuracy and response time.

The participants in both groups correctly categorized 92% of the non-famous names, and 88% (exercise group) to 89% (rest group) of the famous names. The response times were slightly faster among the exercise group than the rest group. However, the differences in accuracy and response times could have been due to chance.

The researchers found that the FNT comparison of exercise versus rest resulted in 13 regions showing significant semantic processing-related activation after exercise. The regions that showed significant activation included the frontal lobe, inferior temporal, middle temporal, and fusiform gyri. They concluded that the fMRI results provided evidence that a single session of aerobic exercise can influence semantic memory activation in several brain regions involved in semantic memory retrieval.

Based on their findings, the researchers concluded that greater brain activation following a single session of exercise suggests that exercise may increase neural processes underlying semantic memory activation in healthy older adults. These effects were localized to the known semantic memory network, and thus did not appear to reflect a general or widespread increase in brain blood flow.

The full text of “Semantic Memory Activation After Acute Exercise in Healthy Older Adults” was published April 25, 2019, by Journal of the International Neuropsychological Society. An abstract is available online at https://www.cambridge.org/core/journals/journal-of-the-international-neuropsychological-society/article/semantic-memory-activation-after-acute-exercise-in-healthy-older-adults/07DE0F919CEFBCE268A95474DFA1BC47 (accessed May 10, 2019).

For more information, contact: J. Carson. Smith, II, Associate Professor, Department of Kinesiology and Director of Kinesiology Undergraduate Honors Program, University of Maryland, 2351 SPH Building, College Park, Maryland 20742; 301-405-0344; Email: carson@umd.edu; Website: https://sph.umd.edu/people/j-carson-smith

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