Effects of exercise interventions for specific cognitive domains in old adults with mild cognitive impairment A protocol of subgroup meta-analysis of randomized controlled trials

Background: Mild cognitive impairment (MCI) is the clinical prognosis that leads to dementia. Early intervention of MCI is critical to protect against dementia. Exercise intervention has gained popularity for the management of MCI. Most current studies have focused only on improvements made by exercise interventions on the global/general cognitive function and/or a specific cognitive function. However, no studies have been performed on a subgroup analysis of the effects of exercise interventions on different cognitive domains of the elderly with MCI. The exploration of this issue will help to clarify the influence and through a preliminary analysis identify the level of influence of exercise interventions on particular cognitive domains, and it will provide the theoretical framework for the construction of precise exercise intervention strategies for MCI patients. Methods: A systematic review of electronic databases (MEDLINE, Embase, The Cochrane Library, Web of Science, CNKI, the Wan Fang Database, and CBM), supplemented by expert contact, reference and citation checking, and gray literature searches have been conducted. There is no restriction on language or publication status. Cochrane Handbook for Systematic Reviews of Interventions and add another 3 items according to PEDpro, including "the type of statistical analyses used (true intention-to-treat vs other)," "eligibility criteria," and "baseline comparability," are used to assess the risk of bias. Primary outcomes of interest are standardized measurements of executive functions, memory, language, processing speed, and attention. If possible, we conduct a meta-analysis to synthesize the evidence for each outcome. Results: This study will provide a high-quality synthesis of current evidence of exercise for MCI patients. Conclusion: The conclusion of this systematic review will provide evidence to judge whether exercise is an effective intervention for patient with MCI and preliminary ranking of the effects of exercise on specific cognitive domains. Prospero registration number: CRD42018093902