Air Pollution and Incidence of Dementia: A Systematic Review and Meta-analysis.

BACKGROUND AND OBJECTIVES: Studies of association between air pollution and incidence of dementia have shown discrepant results. The aim of this study was to evaluate the association between air pollution and dementia. METHODS: In this systematic review and meta-analysis, PubMed, MEDLINE, EMBASE, PsycINFO, Scopus, and Web of Science were searched and updated in August 2021. Population-based cohort studies that reported on hazard ratio (HR) of dementia in association with exposure to fine particulate matter (PM2·5), nitrogen oxides (NOX), nitrogen dioxide (NO2), or ozone (O3) in those aged >40 years were included. Data were extracted by 2 independent investigators. The main outcome was the pooled HR for dementia per increment of pollutant, calculated using a random-effects model. Results were reported in accordance with PRISMA guidelines. The protocol was registered in PROSPERO (registration number: CRD42020219036). RESULTS: A total of 20 studies were included in the systematic review, and 17 provided data for the meta-analysis. The total included population was 91,391,296, with 5,521,111 (6%) being diagnosed with dementia. A total of 12, 5, 6, and 4 studies were included in the meta-analyses of PM2·5, NOX, NO2, and O3, respectively. The risk of dementia increased by 3% per 1 µg/m3 increment in PM2·5 (HR, 1.03; 95% CI [1.02-1.05]; I2 = 100%). The association between dementia per 10 µg/m3 increment in NOX (HR, 1.05; 95% CI [0.99-1.13]; I2 = 61%), NO2 (HR, 1.03; 95% CI [1.00-1.07]; I2 = 94%), and O3 levels (HR, 1.01; 95% CI [0.91-1.11]; I2 = 82%) was less clear, although a significant association could not be ruled out, and there was high heterogeneity across studies. DISCUSSION: Existing evidence suggests a significant association between exposure to PM2·5 and incidence of dementia and nonsignificant association between dementia and NOX, NO2, and O3 exposure. However, results should be interpreted in light of the small number of studies and high heterogeneity of effects across studies.

Relation of fasting and postprandial and plasma glucose with hemoglobinA1c in diabetics.

CONTEXT: Control of plasma glucose could prevent the progression of most of the complications of diabetes and hemoglobinA1c (HbA1c) is the most important criterion controlling these long-term complications. AIMS: This study was performed to assess the effect of fasting plasma glucose (FPG) and two- hour postprandial plasma glucose (2hpp) levels on HbA1c. MATERIALS AND METHODS: In this descriptive, cross-sectional study; 300 patients were enrolled, assessed, and followed up at the clinic of the Diabetic Center of the University of Medical Science, Hamadan, Iran. All studied patients were diagnosed type 1 or 2 diabetes mellitus. Sampling was performed; we assessed FPG and 2hpp plasma glucose at baseline and at every two weeks to one month-as needed. HbA1c was assessed at the end of study. Results were analyzed by Pierson Covariance and Multiple Regression methods. RESULTS: The mean plasma glucose in three groups of HbA1c (good to fair) were 148.5 +/- 56.80 mg/dl at fasting, and 199.70 +/- 53.01 mg/dl at two hours after breakfast (2hpp) and mean concentration of HbA1c were 8.41 +/- 1.1 %. The plasma glucose level and HbA1c were 0.312 for fasting and, 0.416 for 2hpp at covariant value. CONCLUSION: The postprandial (after breakfast) plasma glucose has closer association to glycosylated hemoglobin than fasting plasma glucose, therefore evaluating postprandial plasma glucose should be our focus.