Effectiveness of Physical Exercise on Alzheimer’s disease. A Systematic Review

A systematic review of randomized controlled trials was conducted to determine the effect of physical exercise on physical-functional capacity, cognitive performance, neuropsychiatric symptoms, and quality of life in a population of older people with Alzheimer´s disease.Pubmed, Scopus, PEDro, Web of Science, CINAHL, Cochrane Library, grey literature and a reverse search from inception to April 2021 were searched to identify documents.Publications investigating the effect of any type of physical exercise-based intervention in any of its multiple modalities on physical-functional capacity, cognitive performance, neuropsychiatric symptoms, and quality of life were searched.The data were extracted into predesigned data extraction tables. Risk of bias was evaluated through the PEDro scale and its internal validity scale.A total of 8 different randomized controlled trials with a total sample of 562 non-overlap Alzheimer disease patients between 50-90 years and a mean age of 75.2 ± 3.9 years were eligible for analyses. Physical-functional capacity was evaluated in 6 of 8 studies and cognitive performance was evaluated in 5 of 8 studies, all of them showed improvements in these variables when compared with the controls, except for two studies in physical-functional capacity and one study for cognitive performance. In the physical-functional capacity and cognitive performance variables, aerobic physical exercise was used in isolation, or in a multimodal way, combining aerobic, strength and balance exercise, from 2 to 7 weekly sessions with doses between 30 and 90 minutes, and a duration of the program comprised of 9 weeks to 6 months. Neuropsychiatric symptoms and quality of life were evaluated in 2 of 8 studies, which the intervention groups experienced significant improvements when compared with the control groups, except for one study that found similar differences in quality of life between both groups. In the neuropsychiatric symptoms and quality of life variables, only aerobic physical exercise was used, in a more homogeneous way, from 2 to 3 weekly sessions with doses of 30 to 60 minutes, and a total program duration of 9 to 16 weeks.Despite the scarcity of studies, especially those based on multimodal proposals, and the heterogeneity in the protocols, this systematic review found moderate to limited evidence that aerobic physical exercise on its own or combined in a multimodal program that also includes strength and balance exercise can be a useful tool in the management of patients with Alzheimer's disease with the aim of maintaining and/or improving physical-functional capacity and cognitive performance. In addition, this review found moderate evidence of the positive impact that aerobic physical exercise could have in reducing neuropsychiatric symptoms and improving quality of life in patients with Alzheimer´s disease. PROSPERO registration number: CRD42021229891.