Secular trends in chronic respiratory diseases mortality in Brazil, Russia, China, and South Africa: a comparative study across main BRICS countries from 1990 to 2019

Background As the emerging economies, the BRICS (Brazil, Russia, India, China, and South Africa) shared 61.58% of the global chronic respiratory diseases (CRD) deaths in 2017. This study aimed to assess the secular trends in CRD mortality and explore the effects of age, period, and cohort across main BRICS countries. Methods Data were obtained from the Global Burden of Disease Study (GBD) 2019 and analyzed using the age-period-cohort (APC) model to estimate period and cohort effects between 1990 and 2019. The net drifts, local drifts, longitudinal age curves, period/cohort rate ratios (RRs) were obtained through the APC model. Results In 2019, the CRD deaths across the BRICS were 2.39 (95%UI 1.95 to 2.84) million, accounting for 60.07% of global CRD deaths. Chronic obstructive pulmonary disease (COPD) and asthma remained the leading causes of CRD deaths. The age-standardized mortality rates (ASMR) have declined across the BRICS since 1990, with the most apparent decline in China. Meanwhile, the downward trends in CRD death counts were observed in China and Russia. The overall net drifts per year were obvious in China (-5.89%; -6.06% to -5.71%), and the local drift values were all below zero in all age groups for both sexes. The age effect of CRD presented increase with age, and the period and cohort RRs were following downward trends over time across countries. Similar trends were observed in COPD and asthma. The improvement of CRD mortality was the most obvious in China, especially in period and cohort effects. While South Africa showed the most rapid increase with age across all CRD categories, and the period and cohort effects were flat. Conclusions BRICS accounted for a large proportion of CRD deaths, with China and India alone contributing more than half of the global CRD deaths. However, the declines in ASMR and improvements of period and cohort effects have been observed in both sexes and all age groups across main BRICS countries. China stands out for its remarkable reduction in CRD mortality and its experience may help reduce the burden of CRD in developing countries.

A Reevaluation of the 1990 “Minnesota Study of Twins Reared Apart” IQ Study

In 1990, Thomas J. Bouchard, Jr. and colleagues published the widely cited 1990 “Minnesota Study of Twins Reared Apart” (MISTRA) Science IQ study. To arrive at the conclusion that “IQ is strongly affected by genetic factors,” Bouchard and colleagues omitted their control group reared-apart dizygotic twin (“DZA”) IQ-score correlations. Near-full-sample correlations published after the study’s 2000 endpoint show that the reared-apart monozygotic twin (“MZA”) and DZA group IQ correlations did not differ at a statistically significant level, suggesting that the study failed the first step in determining that IQ scores are influenced by heredity. After bypassing the model-fitting technique they used in most non-IQ MISTRA studies, the researchers assumed that the MZA group IQ-score correlation alone “directly estimates heritability.” This method was based on unsupported assumptions by the researchers, and they largely overlooked the confounding influence of cohort effects. Bouchard and colleagues then decided to count most environmental influences they did recognize as genetic influences. I conclude that the MISTRA IQ study failed to discover genetic influences on IQ scores and cognitive ability across the studied population, and that the study should be evaluated in the context of psychology’s replication problem.

Effects of age, period, and birth cohort on homicide mortality in the city of São Paulo, Brazil, from 1996 to 2015

Although São Paulo is the most populous city in Brazil - one of the world’s most violent countries - a significant reduction in its homicide mortality rate (HMR) has been detected. This study aims to estimate the effects of age, period, and birth cohort on the trend of homicide mortality according to sex in the city of São Paulo, from 1996 to 2015. An ecological study was undertaken with data on deaths by homicide for both sexes, in all age brackets, in the city of São Paulo. Poisson models were adjusted for each sex to estimate the age-period-cohort effects. In total, 61,833 deaths by homicide were recorded among males and 5,109 among females. Regardless of the period, the highest HMR occurred in the 20-24 age bracket. Higher HMRs were found in those born in the 1970s and 1980s. The complete model, with age-period-cohort effects, were the best fit to the data. The risk of death by homicide declined over the periods, with lower intensity in the final five years (2011-2015), for both males (RR = 0.48; 95%CI: 0.46; 0.49) and females (RR = 0.52; 95%CI: 0.47; 0.57). A reduction was found in the risk of homicide, regardless of the sex or age bracket, and also in recent cohorts. However, the intensity of such reductions has been decreasing over time, which suggests that the public policies adopted have limited potential to maintain these achievements.

GRAPHICAL APPROACH TO AGE-PERIOD-COHORT ANALYSIS

The paper presents the graphical approach to decomposition of APC effect in cohort studies (mainly applied to demographic phenomena) using multilevel or accelerated longitudinal design. The aim of the paper is to present and visualize the pure age, period and cohort effects based on simulated data with an increment of five for each successive age, period and cohort variation. In cohort analysis on real data all of the effects are usually interrelated. The analysis shows basic patterns of two-variate APC decomposition (age within period, age within cohort, cohort within period, period within age, cohort within age, period within cohort) and reveals the trajectory of curves for each of the pure effects. The APC plots are developed using apc library of R package.

Covid-19 and Collective Memory Among Malaysians: Does Generation Matter?

The present study aims to understand the impact of Covid-19 on the collective memory among Malaysian generational cohorts. Our research draws on a nationwide survey conducted from July-September 2020 during the second pandemic wave in Malaysia. Respondents were asked to report “the national or world events or changes over the past 60 years” that seemed to them especially important and explain the reasons for their choices. As expected, the result indicated Covid-19 as the most frequently mentioned event. Despite the primacy and recency of the event, we found significant cohort effects on the collective memory of Covid-19, with lower recall recorded among the older generation as compared to the younger generation, which provided stronger support to the Critical Years Hypothesis. Interesting cohort experiences emerge in the meaning attached to Covid-19 across different generational cohorts through open-ended follow-up questions.

Temperature-induced Multi-species Cohort Effects in Sympatric Snakes

In reptiles, reproductive maturity is often determined by size rather than age. Consequently, growth early in life may influence population dynamics through effects on generation time and survival to reproduction. Because reproductive phenology and pre- and post-natal growth are temperature-dependent, environmental conditions may induce multi-species cohort effects on body size in sympatric reptiles. I present evidence of this using ten years of neonatal size data for three sympatric viviparous snakes, Dekay’s Brownsnakes (Storeria dekayi), Red-bellied Snakes (S. occipitomaculata) and Common Gartersnakes (Thamnophis sirtalis). End-of-season neonatal size varied in parallel across species such that snout-vent length was 36-61% greater and mass was 65-223% greater in years when gestating females could achieve higher April-May (vs. June-July or August-September) operative temperatures. Thus, temperature had a larger impact during follicular enlargement and ovulation than during gestation or post-natal growth. Multi-species cohort effects like these may affect population dynamics and increase with climate change.

Trends in Dementia Prevalence in the United States, 1995-2019: An Age-Period-Cohort-Interaction Analysis

Previous studies have indicated that age-specific dementia prevalence has declined in the United States and other high-income countries. However, these studies have been limited by estimating temporal change in dementia rates on a strictly period basis, with little attention to possible cohort effects. Distinguishing age, period, and cohort effects is both methodologically and theoretically important for identifying the etiological factors driving dementia decline in the population. In this study, we apply the novel Age-Period-Cohort-Interaction (APC-I) model, which defines cohort effects as the interaction between age and period main effects. The APC-I model improves on earlier APC models (e.g., the accounting method) by solving the linear dependence between predictors through theoretical clarification instead of statistical manipulation. We use the APC-I model to estimate period and cohort trends in dementia prevalence using data from the Health and Retirement Study (HRS). Our analysis points to significant period and cohort effects. Dementia prevalence declined significantly between the periods 1995-1999 and 2015-2019. At the same time, cohorts born in the 1940s had significantly lower odds of dementia than would be expected given age and period main effects. This cohort’s unique protection from dementia has been relatively stable as they have aged. Our study identifies the periods during which and cohorts for whom dementia risk has declined in the United States. Further research is needed to specify the period factors (e.g., broad based improvements in nutrition) and cohort factors (e.g., increases in educational attainment) that are responsible for these trends.