The association of exposure to air pollution and depression in women; a cross-sectional study of a middle-income country

Association between urbanization and metabolic syndrome in low- and middle-income countries: A systematic review and meta-analysis

AIMS

The prevalence of metabolic syndrome (MetS) is on the rise in an increasingly urbanized world. The study aimed to review the association between urbanization and MetS in low- and middle-income countries (LMICs).

DATA SYNTHESIS

A comprehensive search of five databases (MEDLINE, Web of Science, Scopus, EMBASE, and CENTRAL) was performed in January 2022 and updated in October 2022. Peer-reviewed studies that met the eligibility selection criteria were included. Search terms were used for the main concepts which are MetS, dietary patterns, and urbanization in LMICs. Study selection was done in two stages and in duplicate. Random effects models were used to calculate the overall pooled prevalence and main study-level characteristics. Out of 9,773 identified studies, nineteen were included in the systematic review and meta-analysis. The studies were done on 313,644 participants (149,616 urban and 164,028 rural). The pooled risk ratio (RR, 95% confidence interval) of MetS between urban and rural dwellers was RR = 1.24; 95%CI [1.15, 1.34] (I2 = 96.0%, P < 0.0001). A relatively higher prevalence of MetS among urban than rural residents has been observed, especially with the International Diabetes Federation criteria (RR = 1.54; 95%CI [1.21, 1.96]; I2 = 65.0%), and in the population in India (RR = 2.19; 95%CI = 1.24, 3.88, I2 = 85%). Overall, the role of dietary patterns in the development of MetS was inconsistent, and few studies showed a lower risk of MetS with adherence to recommended healthy dietary patterns.

CONCLUSIONS

There was an association between urbanization and the high prevalence of MetS. Interventions and policies to reduce the risk of MetS are needed.

The Relationship between Ambient Fine Particulate Matter (PM2.5) Pollution and Depression: An Analysis of Data from 185 Countries

Several studies have identified a relationship between air pollution and depression, particularly in relation to fine particulate matter (PM2.5) exposure. However, the strength of this association appears to be moderated by variables such as age, gender, genetic vulnerability, physical activity, and climatic conditions, and has not been assessed at a cross-national level to date. Moreover, certain studies in this field have yielded negative results, and there are discrepancies between the results obtained in high-income countries and those from low- and middle-income countries. The current study examines cross-sectional and longitudinal associations between the incidence of depression in each country, based on Global Burden of Disease Study data, and the average national level of PM2.5 based on the World Health Organization’s database, over the past decade (2010–2019). The observed associations were adjusted for age, gender, level of physical activity, income, education, population density, climate, and type of depression. It was observed that while PM2.5 levels showed significant cross-sectional associations with the incidence of depression, longitudinal analyses were not suggestive of a direct causal relationship. These findings are discussed in the light of recent contradictory results in this field, and the need to consider the intermediate roles of a number of individual and environmental factors.