Objective: To systematically review the effect of physical exercise on cognition in older adults with and without cognitive decline.
Data sources: : Randomized controlled trials were identified by literature searches in PubMed, EMBASE, CENTRAL, PsycINFO, and AgeLine.
Study selection: Papers were included on the basis of predefined inclusion criteria.
Data extraction: Data on study population, exercise intervention, and effectiveness were extracted. Two independent reviewers assessed methodological quality.
Data synthesis: Twenty-three studies were included-15 among cognitively healthy subjects and 8 among subjects with cognitive decline. Seven studies were qualified as high-quality studies, 2 in cognitively healthy subjects and 5 in subjects with cognitive decline. In cognitively healthy subjects, significant beneficial intervention effects were observed in 5 studies on information processing, executive function, or memory. Interventions in these studies included aerobic exercise only (n = 2); strength exercise (n = 1); strength and balance exercise (n = 1); or all-round exercise including aerobic, strength, balance and flexibility training (n = 1). In subjects with cognitive decline, 5 studies observed beneficial effects on general cognition, executive functions, and memory. Interventions included aerobic (n = 3) or strength exercise combined with flexibility or balance exercise (n = 2).
Conclusions: Beneficial effects of various exercise programs on aspects of cognition have been observed in studies among subjects with and without cognitive decline. The majority of the studies, however, did not find any effect. The small number of included studies; lack of high-quality studies; and the large variability in study populations, exercise protocols, and outcome measures complicate interpretation of the results. More high-quality trials are needed to assess the effects of different types of exercise on cognitive function in older adults with and without cognitive decline.