Biological aspects of human migration and mobility

Do contrasting socio-ecological conditions bring difference in premenstrual syndrome and its concomitants? A sedente-migrant comparative study from Eastern India

OBJECTIVES

We asked in our research whether the premenstrual syndrome (PMS) and its concomitants, differ between "sedente" and "migrant" populations hailing from the same ethnic group, owing to their living in contrasting socio-ecological conditions.

METHODS

A total of 501 Oraon adolescents (sedente: 200, migrant: 301) were studied. Data on PMS was reported retrospectively using a list of 29 standard symptoms. Principal component analysis (PCA) was applied on PMS. PCA, which resulted in six principal components (PC1 to PC6) were loaded with "behavioral and cognitive," "negative mood," "pain and fluid retention," "vestibular and breast tenderness," and "fatigue," and/or "gastrointestinal" symptoms. Step-wise hierarchical regression was applied using migration status (step 1), socio-demographic (step 2), menstrual (step 3), and nutritional and lifestyle variables (step 4) as concomitants for each principal component.

RESULTS

Significantly, a greater number of migrants reported PMS but of milder intensity, unlike the sedentes. Significant sedente-migrant differences were found in the concomitants for PMS. Multivariate analyses showed differential socio-demographic (occupational, educational and wealth status, religion), nutritional (dietary carbohydrate protein and fat, tea intake, body mass index, percent body fat, waist hip ratio, fat mass index), menstrual (age at menarche, cycle length, dysmenorrhoea) and anemic status of the sedentes and the migrants were significantly associated with PMS.

CONCLUSIONS

Sedente and migrant participants, despite hailing from the same ethnic group, sharply differed in the prevalence of PMS and its concomitants owing to their living in contrasting socio-ecological conditions.

Cardiovascular risk factors across different levels of urbanization in Brazilian Afro‐derived communities ( quilombos )

OBJECTIVES

The frequency of cardiovascular diseases has increased throughout the world. People of African descent have been disproportionately affected, particularly if they reside in urban settings. In this work, we evaluate risk factors associated with cardiovascular diseases (CVD) and other chronic diseases in rural and urban Afro-derived communities (quilombo) in Central Brazil. We also determine if there are associations between the frequency of CVD risk factors, sex, and proximity to urban environments.

METHODS

Through a cross-sectional study of participants (n = 347) within three Brazilian Afro-derived communities: Kalunga (a semi-isolated rural community; n = 214), Cocalinho (a non-isolated rural village; n = 70), and Pé do Morro (an urban community; n = 63), we collected data regarding chronic disease (i.e., CVD, diabetes, and hypertension) risk through questionnaires, anthropometrics, blood pressure, and blood samples using standard protocols. Differences between variables were tested by the Chi-square test of Pearson and Fisher's Exact Test, independent sample t-tests, analysis of variances, and Kruskal-Wallis tests (p ≤ .05).

RESULTS

The prevalence of hypertension, overweight, obesity, and other cardiovascular risk factors were higher in the non-isolated rural and urban communities than in the semi-isolated rural community. We found significant sex differences in the distribution of the CVD risk factors, with all occurring at a higher frequency among females.

CONCLUSIONS

Our findings indicate that Brazilian Afro-derived communities are currently going through an epidemiological transition. The urban lifestyle and its environmental factors are likely contributing to an escalation in cardio-metabolic disease risk. However, the magnitude of this transition differentially impacts the sexes, as females suffer a higher frequency of risk factors compared to males.

The macroecology of the COVID-19 pandemic in the Anthropocene

Severe acute respiratory syndrome coronavirus 2, the virus that causes coronavirus disease 2019 (COVID-19), has expanded rapidly throughout the world. Thus, it is important to understand how global factors linked with the functioning of the Anthropocene are responsible for the COVID-19 outbreak. We tested hypotheses that the number of COVID-19 cases, number of deaths and growth rate of recorded infections: (1) are positively associated with population density as well as (2) proportion of the human population living in urban areas as a proxies of interpersonal contact rate, (3) age of the population in a given country as an indication of that population's susceptibility to COVID-19; (4) net migration rate and (5) number of tourists as proxies of infection pressure, and negatively associated with (5) gross domestic product which is a proxy of health care quality. Data at the country level were compiled from publicly available databases and analysed with gradient boosting regression trees after controlling for confounding factors (e.g. geographic location). We found a positive association between the number of COVID-19 cases in a given country and gross domestic product, number of tourists, and geographic longitude. The number of deaths was positively associated with gross domestic product, number of tourists in a country, and geographic longitude. The effects of gross domestic product and number of tourists were non-linear, with clear thresholds above which the number of COVID-19 cases and deaths increased rapidly. The growth rate of COVID-19 cases was positively linked to the number of tourists and gross domestic product. The growth rate of COVID-19 cases was negatively associated with the mean age of the population and geographic longitude. Growth was slower in less urbanised countries. This study demonstrates that the characteristics of the human population and high mobility, but not population density, may help explain the global spread of the virus. In addition, geography, possibly via climate, may play a role in the pandemic. The unexpected positive and strong association between gross domestic product and number of cases, deaths, and growth rate suggests that COVID-19 may be a new civilisation disease affecting rich economies.

A LONGITUDINAL ANALYSIS OF INTERNAL MIGRATION, DIVORCE AND WELL-BEING IN CHINA

The rapid economic growth in China has been accompanied by increases in internal migration as well as marital dissolution. Using longitudinal data from China Health and Nutrition Surveys covering over 19,000 individuals during 1989-2011, this study modelled the inter-relationships between internal migration, divorce and individual well-being, tackling conceptual and methodological aspects such as the joint determination of variables. First, random effects probit models showed that the migration periods of husbands and wives significantly increased their respective chances of divorce. Second, results from dynamic random effects models for self-reported health showed different effects of separation periods for husbands and wives; divorce did not significantly lower health status. Third, dynamic models for systolic and diastolic blood pressures showed significant effects of migration durations of husbands and wives; men had lower systolic blood pressure following divorce thereby indicating beneficial effects for unhappily married couples. The implications of the findings are discussed.