In this meta-analysis of 28 randomized controlled trials (totaling 2,063 older adults with or without mild cognitive impairment), physical exercise slightly improved working memory. In the subgroup analyses based on exercise type, only multi-component exercise and mind-body exercise improved working memory.
Working memory is a system for storing and manipulating information during complex cognitive tasks, such as learning, reasoning, and comprehending. The performance of working memory generally declines with age, potentially due to age-related neural changes in the brain.
This meta-analysis of 28 randomized controlled trials (RCTs) examined the effects of physical exercise on the working memory of 2,063 older adults aged 62–86 without dementia or mental disorders.
The participants had mild cognitive decline in 11 of the 28 trials. Four types of exercise were used: aerobic exercise (9 trials), resistance exercise (6), multi-component exercise (MCE, 6), and mind–body exercise (MBE, 7). The comparators included balance exercise, stretching, health education, and no intervention.
Subgroup analyses were performed based on the following factors: age and cognitive status of the participants; type of tool used to measure working memory; type, intensity, duration, and frequency of exercise; type of comparator; and trial duration.
In the main analysis, physical exercise improved working memory with a small effect size, a moderate degree of heterogeneity, and no publication bias.
In the subgroup analyses, working memory was improved by MCE and MBE (but not aerobic or resistance exercise), by exercise performed 1–2 or 3–4 (but not ≥5) times per week, and by exercise performed at low or moderate (but not vigorous) intensity.
The methodological quality of the included trials ranged from fair to excellent and was overall good.
The big picture
A 2017 meta-analysis of 15 trials found that chronic physical activity slightly improved working memory in healthy participants, with a moderation analysis showing that the improvements were statistically significant only in adults aged ≥65. While only 5 of the 15 trials were in older adults, the findings of this meta-analysis support the findings of the main analysis of the meta-analysis summarized here.
With regard to exercise type, in previous meta-analyses as in the present one, neither aerobic exercise nor resistance exercise improved the working memory of older adults. The relative success of MCE and MBE may be due to their combining aerobic, resistance, balance, and stretching components, resulting in complementary neurobiological and physiological effects on working memory.
With regard to exercise frequency, a 2016 meta-analysis of 18 RCTs (802 participants) found that both low and high frequencies improved cognitive function (low frequencies to a greater extent). 22 This finding contrasts with that of the present meta-analysis — which, it should be noted, included only a handful of trials in its subgroups for higher exercise frequency and vigorous intensity (which means that, in those respects, we should interpret its findings with particular caution).
Finally, let’s note that aerobic exercise and resistance exercise may improve other aspects of cognition (such as attention, processing speed, and global cognitive function) in older adults.
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