To determine whether Tai Chi (TC) is effective in slowing cognitive decline in older populations with mild cognitive impairment (MCI), we performed a systematic review and meta-analysis of randomized controlled trials (RCTs) on Tai Chi and MCI. We searched eight electronic databases (PubMed, PsycINFO, Wanfang, Web of Science, MEDLINE, CNKI, EBSCO, and the Cochrane Central Register of Controlled Trials) for appropriate RCTs published up to August 2019. For those studies included, the data were extracted, methodological quality was evaluated, and then meta-analysis was performed using Review Manager software (version 5.3). A total of 11 of the studies were available for systematic review, which together included 1061 participants, met the inclusion criteria, and ten of these were included in the meta-analysis. For most RCTs, the methodological quality was moderate. The meta-analysis revealed that Tai Chi could significantly improve global cognitive function; memory and learning; mental speed and attention; ideas, abstraction, figural creations, and mental flexibility; and visuospatial perception. The present review adds to the evidence showing that Tai Chi is potentially beneficial in improving cognitive functions among elderly people with MCI. However, strictly designed and well-reported RCTs are required.

Objectives: Blood lipid profiles have been ambiguously reported as biomarkers of AD in recent years. This study was conducted to evaluate the correlation between blood lipid levels and AD in later-life and to explore the effectiveness and reliability of blood lipid profiles as biomarkers of AD. Methods: Database searching was conducted using PubMed, the Cochrane Library, EMBASE, and Medline. This study was designed following the Meta-analysis of Observational Studies in Epidemiology (MOOSE) criteria. Review Manager 5.3 (RevMan 5.3) software was adopted to perform meta-analysis evaluating the standard mean difference (SMD) with its 95% confidence intervals (CI). Results: A total of 5,286 participants were enrolled from 27 case-control studies in this meta-analysis. The pooled results demonstrated that total cholesterol (TC) level was significantly associated with AD in late-life (SMD = 0.17, 95% CI: [0.01, 0.32], P = 0.03), especially in the subgroup under 70 years old (SMD: 0.45, 95% CI: [0.11, 0.79], P = 0.01) and the subgroup of Western population (SMD: 0.29, 95% CI: [0.04, 0.53], P = 0.02). In the subgroup under 70 years old, the high-density lipoprotein cholesterol (HDL-C) level (SMD = −0.50, 95% CI: [−0.76, −0.25], P = 0.0001) and the low-density lipoprotein cholesterol (LDL-C) level (SMD = 0.59, 95% CI: [0.02, 1.16], P = 0.04) in the AD group were significantly lower and higher than in the control group, respectively. In the subgroup with a sample size larger than 100 subjects, the LDL-C level was significantly higher in AD patients than in the control elderly group (SMD = 0.31, 95% CI: [0.05, 0.56], P = 0.02). There was no significant association between triglyceride (TG) levels and AD in later-life (SMD = −0.00, 95% CI: [−0.12, 0.12], P = 1.00). Tang et al. Association Between Lipids and AD Conclusion: TC can be a new predictive biomarker of AD or cognitive decline in later-life. Increased TC levels are found to be associated with an elevated risk of AD. Decreased HDL-C levels and increased LDL-C levels may relate to an elevated risk of AD in subjects aged 60-70. Further comprehensive researches will be necessary in the future.

This study investigated the benefits of resistance training on cognition in patients with mild cognitive impairment. We searched the PubMed, Embase and Cochrane Library databases, and seven randomized controlled trials were reviewed. We evaluated the risk of bias using the Cochrane Collaboration’s bias assessment tool. Standard mean differences with 95% confidence intervals were calculated for statistical analysis. This meta-analysis assessed three variables: general cognitive function, executive function and working memory. The results indicate that general cognitive function improved significantly (standardized mean difference: 0.53, P=0.04), and further subgroup analyses on frequency and duration per session showed that the subgroups ‘twice a week’ (P=0.01) and ‘duration per session >60 min’ (P=0.0006) exhibited better performance than the subgroups ‘three time a week’ (P=0.47) and ‘duration per session <60 min’ (P=0.53). Additionally, a moderate effect size was found in executive function (standardized mean difference: 0.50, P=0.0003), and there was non-significant effect in working memory (P=0.14). In summary, resistance training may mitigate mild cognitive impairment by improving cognition. Larger-scale studies are recommended to demonstrate the relationship between resistance training and cognition in mild cognitive impairment.