Cognitive interventions for mild cognitive impairment and dementia: An overview of systematic reviews

Conducting an overview of systematic reviews (SRs)/Meta analyses (MAs) to assess the effectiveness of cognitive interventions on participants with mild cognitive impairment (MCI) or dementia and evaluate the methodological quality of SRs/MAs.

PubMed, EMBASE, Cochrane library, Web of science, China National Knowledge Infrastructure (CNKI) and Chinese Biomedical Databases (CBM) were systematically searched from inception to January 1, 2019 to identify SRs/MAs. Three reviewers independently screened the articles, extracted data and assessed the quality of the included studies according to the Assessing the Methodological Quality of Systematic Reviews 2 (AMSTAR-2), the Grading of Recommendations Assessment Development and Evaluation (GRADE) was used to evaluate the quality of evidence.

A total of 22 reviews were included. New meta-analyses (36 RCTs) showed that cognitive interventions were more effective than routine therapies for the alleviation of MCI and dementia symptoms (SMD: 0.62; 95%CI: 0.47, 0.78; I² = 53.9%). The results of AMSTAR-2 showed that the methodological quality of most included studies was critically low, and two reviews were low quality. The lowest score was item 10, none of reviews reported on the sources of funding for the included studies. Followed by the "provide a list of excluded studies and justify the exclusions" item with only one (4.5%) reviews conforming to this item. Results of GRADE manifested that moderate quality evidence was provided in 11 reviews (39.3%), 12 (42.9%) were low quality and 5 (17.8%) were very low.

The present SRs/MAs indicated that persons with MCI or dementia could benefit from cognitive interventions. Future trial designs should focus on measuring changes in individual specific cognitive functions. More high-quality evidence is needed to further determine the effectiveness of cognitive interventions.