Effects of Exercise on Inflammatory, Oxidative, and Neurotrophic Biomarkers on Cognitively Impaired Individuals Diagnosed With Dementia or Mild Cognitive Impairment: A Systematic Review and Meta-Analysis

Although the effects of physical exercise (PE) on cognitive function in dementia and mild cognitive impairment (MCI) have been largely studied, its biochemical effect is still poorly explored. The aim of this systematic review was to investigate the effects of PE on inflammatory, oxidative, and neurotrophic biomarkers of participants with MCI or dementia. Six electronic databases, (PubMed, Cochrane Central, Embase, PEDro, PsycINFO, and SportDiscus) were searched for randomized controlled trials assessing the effects of PE on serum and/or plasma biomarkers of elderly participants with MCI or dementia. After selection process, eight studies were included. Meta-analysis was performed by comparison of changes from baseline, using the random effects method. Meta-analysis showed a significant effect of aerobic exercise on interleukin-6 and tumor necrosis factor alpha decrease and positive effects on brain-derived neurotrophic factor expression. As only one study was included with oxidative biomarker assessment, the effects of PE on oxidative process remain unclear. Finally, even though it was possible to observe positive effects of PE on some biomarkers of MCI and dementia individuals, current evidence does not allow drawing specific practical recommendations such as type, frequency, intensity, or duration of PE in these population. Further researches aiming to estimate the PE effectiveness on biomarkers of MCI and Alzheimer's disease are needed.