Head injury is a risk factor for AD. The magnitude of the risk is proportional to severity and heightened among first-degree relatives of AD patients. The influence of head injury on the risk of AD appears to be greater among persons lacking APOE-epsilon4 compared with those having one or two epsilon4 alleles, suggesting that these risk factors may have a common biologic underpinning.

Background and Aims During the current Coronavirus Disease 2019 (COVID-19) pandemic, patients with diabetes face disproportionately more. This study was performed to clarify anti-inflammatory effects of anti-diabetic agents on COVID-19 in patients with diabetes. Methods and Results Relevant literature was searched on 15 databases up to November 14, 2020 and was updated on April 13, 2021. The pooled ORs along with 95% CIs were calculated to evaluate combined effects. 31 studies with 66,914 patients were included in qualitative and quantitative synthesis. Meta-analysis showed that metformin was associated with a statistically significant lower mortality (pooled OR = 0.62, 95% CI, 0.50–0.76, p = 0.000) and poor composite outcomes (pooled OR = 0.83, 95% CI, 0.71–0.97, p = 0.022) in diabetic patients with COVID-19. Significance of slight lower mortality remained in sulfonylurea/glinides (pooled OR = 0.93, 95% CI, 0.89–0.98, p = 0.004), but of poor composite outcomes was not (pooled OR = 1.48, 95% CI, 0.61–3.60, p = 0.384). Dipeptidyl peptidase-4 inhibitors (DPP-4 inhibitors) were associated with statistically non-significant lower mortality (pooled OR = 0.95, 95% CI, 0.72–1.26, p = 0.739) or poor composite outcomes (pooled OR = 1.27, 95% CI, 0.91–1.77, p = 0.162) of COVID-19 in diabetic patients. Conclusion Metformin might be beneficial in decreasing mortality and poor composite outcomes in diabetic patients infected with SARS-CoV-2. DPP-4 inhibitors, sulfonylurea/glinides, SGLT-2 inhibitors, and GLP-1RA wouldn't seem to be adverse. There's insufficient evidence to conclude effects of other anti-diabetic agents. Limited by retrospective characteristics, with relative weak capability to verify causality, more prospective studies, especially RCTs are needed. Registration number: PROSPERO-CRD42020221951.

Background Famotidine was reported to potentially provide benefits to Coronavirus Disease 2019 (COVID-19) patients. However, it remains controversial whether it is effective in treating COVID-19. Aims This study aimed to explore whether famotidine use is associated with reduced risk of the severity, death, and intubation for COVID-19 patients. Methods This study was registered on International Prospective Register of Systematic Reviews (PROSPERO) (ID: CRD42020213536). A comprehensive search was performed to identify relevant studies up to October 2020. I-squared statistic and Q-test were utilized to assess the heterogeneity. Pooled risk ratios (RR) and 95% confidence intervals (CI) were calculated through the random effects or fixed effects model according to the heterogeneity. Subgroup analyses, sensitivity analysis, and publication bias assessment were also conducted. Results Five studies including 36,635 subjects were included. We found that famotidine use was associated with a statistically non-significant reduced risk of progression to severe disease, death, and intubation for Coronavirus Disease 2019 (COVID-19) patients (pooled RR was 0.82, 95% CI = 0.52–1.30, P = 0.40). Conclusion Famotidine has no significant protective effect in reducing the risk of developing serious illness, death, and intubation for COVID-19 patients. More original studies are needed to further clarify whether it is associated with reduced risk of the severity, death, and intubation for COVID-19 patients.

Background The effect of using Angiotensin-converting enzyme inhibitors (ACEIs) and Angiotensin-receptor blockers (ARBs) on the risk of coronavirus disease 2019 (COVID-19) is a topic of recent debate. Although studies have examined the potential association between them, the results remain controversial. This study aims to determine the true effect of ACEI/ARBs use on the risk of infection and clinical outcome of COVID-19. Methods Five electronic databases (PubMed, Web of science, Cochrane library, China National Knowledge Infrastructure database, medRxiv preprint server) were retrieved to find eligible studies. Meta-analysis was performed to examine the association between ACEI/ARBs use and the risk of infection and clinical outcome of COVID-19. Results 22 articles containing 157,328 patients were included. Use of ACEI/ARBs was not associated with increased risk of infection (Adjusted OR: 0.96, 95% CI: 0.91-1.01, I2=5.8%) or increased severity (Adjusted OR: 0.90, 95% CI: 0.77-1.05, I2=27.6%) of COVID-19. The use of ACEI/ARBs was associated with lower risk of death from COVID-19 (Adjusted OR: 0.66, 95% CI: 0.44-0.99, I2=57.9%). Similar results of reduced risk of death were also found for ACEI/ARB use in COVID-19 patients with hypertension (Adjusted OR: 0.36, 95% CI: 0.17-0.77, I2=0). Conclusion This study provides evidence that ACEI/ARBs use for COVID-19 patients does not lead to harmful outcomes and may even provide a beneficial role and decrease mortality from COVID-19. Clinicians should not discontinue ACEI/ARBs for patients diagnosed with COVID-19 if they are already on these agents. Keywords: COVID-19; Angiotensin-converting enzyme inhibitor; Angiotensin-receptor blockers; risk; systematic review; meta-analysis