We investigated the heritability of educational attainment and how it differed between birth cohorts and cultural–geographic regions. A classical twin design was applied to pooled data from 28 cohorts representing 16 countries and including 193,518 twins with information on educational attainment at 25 years of age or older. Genetic factors explained the major part of individual differences in educational attainment (heritability: a² = 0.43; 0.41–0.44), but also environmental variation shared by co-twins was substantial (c² = 0.31; 0.30–0.33). The proportions of educational variation explained by genetic and shared environmental factors did not differ between Europe, North America and Australia, and East Asia. When restricted to twins 30 years or older to confirm finalized education, the heritability was higher in the older cohorts born in 1900–1949 (a² = 0.44; 0.41–0.46) than in the later cohorts born in 1950–1989 (a² = 0.38; 0.36–0.40), with a corresponding lower influence of common environmental factors (c² = 0.31; 0.29–0.33 and c² = 0.34; 0.32–0.36, respectively). In conclusion, both genetic and environmental factors shared by co-twins have an important influence on individual differences in educational attainment. The effect of genetic factors on educational attainment has decreased from the cohorts born before to those born after the 1950s.

The COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) project is a large international collaborative effort to analyze individual-level phenotype data from twins in multiple cohorts from different environments. The main objective is to study factors that modify genetic and environmental variation of height, body mass index (BMI, kg/m²) and size at birth, and additionally to address other research questions such as long-term consequences of birth size. The project started in 2013 and is open to all twin projects in the world having height and weight measures on twins with information on zygosity. Thus far, 54 twin projects from 24 countries have provided individual-level data. The CODATwins database includes 489,981 twin individuals (228,635 complete twin pairs). Since many twin cohorts have collected longitudinal data, there is a total of 1,049,785 height and weight observations. For many cohorts, we also have information on birth weight and length, own smoking behavior and own or parental education. We found that the heritability estimates of height and BMI systematically changed from infancy to old age. Remarkably, only minor differences in the heritability estimates were found across cultural–geographic regions, measurement time and birth cohort for height and BMI. In addition to genetic epidemiological studies, we looked at associations of height and BMI with education, birth weight and smoking status. Within-family analyses examined differences within same-sex and opposite-sex dizygotic twins in birth size and later development. The CODATwins project demonstrates the feasibility and value of international collaboration to address gene-by-exposure interactions that require large sample sizes and address the effects of different exposures across time, geographical regions and socioeconomic status.

Park HA, et al. J Korean Med Sci. 2016 Jan;31(1):139-146. https://doi.org/10.3346/jkms.2016.31.1.139

It is estimated that over 60% of out-of-hospital cardiac arrest (OHCA) patients with a shockable rhythm are refractory to current treatment, never achieve return of spontaneous circulation, or die before they reach the hospital. Therefore, we aimed to identify whether field resuscitation time is associated with survival rate in refractory OHCA (rOHCA) with a shockable initial rhythm. This cross-sectional retrospective study extracted data of emergency medical service (EMS)-treated patients aged ≥ 15 years with OHCA of suspected cardiac etiology and shockable initial rhythm confirmed by EMS providers from the OHCA registry database of Korea. A multivariable logistic regression analysis was conducted for survival to discharge and good neurological outcomes in the scene time interval groups. The median scene time interval for the non-survival and survival to discharge patients were 16 (interquartile range (IQR) 13–21) minutes and 14 (IQR 12–16) minutes, respectively. In this study, for rOHCA patients with a shockable rhythm, continuing CPR for more than 15 min on the scene was associated with a decreased chance of survival and good neurological outcome. In particular, we found that in the patients whose transport time interval was >10 min, the longer scene time interval was negatively associated with the neurological outcome.

Background: Cardiopulmonary resuscitation (CPR) is a very critical phenomenon, and to prepare for it, most nurses undertake simulation training, during which learners’ stress levels should be managed. This study aims to evaluate nurses’ stress levels during CPR simulation training using heart rate variability (HRV) measured with a smartwatch and to determine the correlation between individual personality traits and stress levels. Methods: This prospective observational study was conducted from July 2020 to December 2021. For nurses participating in advanced life support training with more than six months of clinical experience, their stress levels while performing as a CPR team leader were measured. Regarding stress levels, heart rate data measured with a smartwatch were processed using Kubios HRV Standard software to generate HRV parameters. The personality of participants was evaluated using the Big Five personality test. The degree of stress according to personality was determined using HRV parameters. Consequently, the correlation between personality and stress according to the clinical experience of cardiac arrest was analyzed. Results: Of the 132 participants, 91.7% were female, and the median age of the sample was 27 years. Agreeable personality had the highest score (32.84±3.83). LF power (r = 0.18, p = 0.04) and HF power (r = 0.20, p = 0.02) showed a significant positive correlation with the agreeableness trait. In subgroup analysis according to the cardiac arrest experience, the agreeableness trait had a positive correlation with a standard deviation of NN intervals (r = 0.24, p = 0.01), root-mean-square of successive differences (r = 0.23, p = 0.02), LF Power (r = 0.26, p = 0.01), and HF power (r = 0.23, p = 0.02), but a negative correlation with mean HR (r = -0.22, p = 0.03). Conclusion: The clinical experience in cardiac arrest and agreeableness were related to acute stress during training. In the future, it is necessary to apply a scenario of a level suitable for individual personality and experience, and evaluate the level and achievement of students.