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Background: Dementia is a critical global public health problem. Previous cohort studies have found that influenza vaccination can decrease the risk of dementia. Objective: This meta-analysis aimed to systematically examine the relationship between influenza vaccination and dementia risk. Methods: We searched PubMed, Embase, Web of Science, ScienceDirect, medRxiv, and bioRxiv for studies investigating dementia risk based on influenza vaccination status, up to September 14, 2022. Relative risks (RRs) and 95% confidence intervals (95% CIs) were pooled in the meta-analysis. Subgroup analyses and sensitivity analyses were conducted as well. Results: Of the 4,087 articles initially reviewed, 6 cohort studies were included in the final meta-analysis, and all eligible studies were at low risk of bias. There were 2,087,195 participants without dementia at baseline (mean age: 61.8–75.5 years, 57.05% males), and 149,804 (7.18%) cases of dementia occurred during 4.00–13.00 years of follow-up. Pooled analysis of adjusted RRs found that influenza vaccination could reduce dementia risk by 31% (RR = 0.69, 95% CI: 0.57–0.83). Subgroup analyses showed that in the study with a mean age of 75–80 years or 75%–100% males, the association was generally weakened compared with studies with a mean age of 60–75 years or 25%–50% males. The results were stable in the sensitivity analyses, and no publication bias was observed. Conclusion: Influenza vaccination in older adults was markedly associated with a decreased risk of dementia. More mechanistic studies and epidemiological studies are needed to clarify the association between influenza vaccination and decreased dementia risk.

The intersection between layered magnetic materials and topological materials combines the advantages of the two, forming a material system with both the magnetic orders and topological properties within the minimum two-dimensional unit, i.e. layered magnetic topological materials. This type of material may host Dirac points, Weyl points, nodal lines, etc. which are associated with helical or chiral electronic states ranging from insulator, semimetal to metal. This results in lots of novel physical problems and effects, which attract much attention of scientists. In this paper, we focus our attention on intrinsic magnetic topological insulator, magnetic Weyl semimetal, magnetic Dirac semimetal, and take them for example to briefly review the interplay between magnetic orders and topological orders and recent experimental results. This emergent area requires further studies to explore more new material candidates, which is a challenging frontier of condensed matter physics.

The intrinsic antiferromagnetic topological insulator MnBi2Te4 and members of its family have been the subject of theoretical and experimental research, which has revealed the presence of a variety of defects and disorders that are crucial in determining the topological and magnetic properties. This also brings about challenges in realizing the quantum states like the quantum anomalous Hall and the axion insulator states. Here, utilizing cryogenic magnetoelectric transport and magnetic measurements, we systematically investigate the effects arising from intrinsic doping by antisite defects and extrinsic doping by Sb in MnBi2Te4 epitaxial films grown by molecular beam epitaxy. We demonstrate that the nonequilibrium condition in epitaxy allows a wide growth window for optimizing the crystalline quality and defect engineering. While the intrinsic antisite defects caused by the intermixing between Bi and Mn can be utilized to tune the Fermi level position as evidenced by a p-to-n conductivity transition, the extrinsic Sb-doping not only compensates for this doping effect but also modifies the magnetism and topology of the film, during which a topological phase transition is developed. Conflicting reports from the theoretical calculations and experimental measurements in bulk crystals versus epitaxial films are addressed, which highlights the intimate correlation between the magnetism and topology as well as the balance between the Fermi-level positioning and defect control. The present study provides an experimental support for the epitaxial growth of the intrinsic topological insulator and underlines that the topology, magnetism, and defect engineering should be revisited for enabling a steady and reliable film production.