Academic performance of opposite-sex and same-sex twins in adolescence:A Danish national cohort study

Testosterone is an important hormone in the sexual differentiation of the brain, contributing to differences in cognitive abilities between males and females. For instance, studies in clinical populations such as females with congenital adrenal hyperplasia (CAH) who are exposed to high levels of androgens in utero support arguments for prenatal testosterone effects on characteristics such as visuospatial cognition and behaviour. The comparison of opposite-sex (OS) and same-sex (SS) twin pairs can be used to help establish the role of prenatal testosterone. However, although some twin studies confirm a masculinizing effect of a male co-twin regarding for instance perception and cognition it remains unclear whether intra-uterine hormone transfer exists in humans. Our aim was to test the potential influences of testosterone on academic performance in OS twins. We compared ninth-grade test scores and teacher ratings of OS (n = 1812) and SS (n = 4054) twins as well as of twins and singletons (n = 13,900) in mathematics, physics/chemistry, Danish, and English. We found that males had significantly higher test scores in mathematics than females (.06–.15 SD), whereas females performed better in Danish (.33–.49 SD), English (.20 SD), and neatness (.45–.64 SD). However, we did not find that OS females performed better in mathematics than SS and singleton females, nor did they perform worse either in Danish or English. Scores for OS and SS males were similar in all topics. In conclusion, this study did not provide evidence for a masculinization of female twins with male co-twins with regard to academic performance in adolescence

Variability Matters

Much of science, including public health research, focuses on means (averages). The purpose of the present paper is to reinforce the idea that variability matters just as well. At the hand of four examples, we highlight four classes of situations where the conclusion drawn on the basis of the mean alone is qualitatively altered when variability is also considered. We suggest that some of the more serendipitous results have their origin in variability

Risk of epilepsy in opposite-sex and same-sex twins: a twin cohort study

Abstract Background There is a complex interaction between female and male sex hormones and the risk of epilepsy. Whether prenatal exposure to higher levels of sex hormones affects the development of epilepsy in childhood or later in life is not well known. The sex hormone environment of fetuses may be affected by the sex of the co-twin. We estimated the risk of epilepsy for twins with an opposite-sex (OS) co-twin compared with twins with a same-sex (SS) co-twin. Methods From the Danish Twin Registry, we identified OS female twins (n = 11,078), SS female twins (n = 19,186), OS male twins (n = 11,080), and SS male twins (n = 20,207) born between 1977 and 2009. The SS twins include monozygotic twins, dizygotic twins, and twins with unknown zygosity. These children were followed up from day 29 after birth until diagnosis of epilepsy, death, emigration, or end of follow-up (31 December 2011) whichever came first. Information on diagnosis of epilepsy was obtained from the Danish National Patient Registry. We calculated hazard ratios (HRs) and 95% confidence intervals (CIs) for epilepsy in the OS twins using a Cox proportional hazards regression model compared with the SS twins. To account for the correlation of twins from the same mother when estimating standard errors, we used the cluster option in Stata. Results We identified 152 OS female twins, 282 SS female twins, 162 OS male twins, and 335 SS male twins diagnosed with epilepsy corresponding to an incidence rate of 9.9 and 9.7 per 10,000 person years for the OS and SS female twins, and 10.6 and 10.9 per 10,000 person years for the OS and SS male twins, respectively. We found a similar risk of epilepsy among the OS and SS female twins [HR = 1.01; 95% CI 0.83–1.24] as well as among the OS and SS male twins [HR = 0.94; 95% CI 0.78–1.14] Conclusions In this population-based study of Danish twins, we did not find difference in the risk of epilepsy between twins with an OS co-twin and twins with a SS co-twin. This applied to both female and male twins. The study therefore does not support the hypothesis that subtle hormone difference in fetal life due to co-twin may play a role in the development of epilepsy later in life

Spousal order of migration, gender, and hospitalization among immigrants in Denmark

Caputo J, Carollo A, Mussino E, et al. Spousal order of migration, gender, and hospitalization among immigrants in Denmark. Scandinavian Journal of Public Health. 2020: 140349482094472.Background: Certain migration contexts that may help clarify immigrants’ health needs are understudied, including the order in which married individuals migrate. Research shows that men, who are healthier than women across most populations, often migrate to a host country before women. Using Danish register data, we investigate descriptive patterns in the order that married men and women arrive in Denmark, as well as whether migration order is related to overnight hospitalizations. Methods: The study base includes married immigrants who lived in Denmark between January 1, 1980 and December 31, 2014 ( N = 13,680). We use event history models to examine the influence of spousal migration order on hospitalizations. Results: The order that married individuals arrive in Denmark is indeed highly gendered, with men tending to arrive first, and varies by country of origin. Risk of hospitalization after age 50 does not depend on whether an individual migrated before, after, or at the same time as their spouse among either men or women. However, among those aged 18+, men migrating before their wives are more likely to experience hospitalizations within the first 5 years of arrival. Conclusions: These findings provide the first key insights about gendered migration patterns in Denmark. Although spousal order of migration is not related to overnight hospitalization among women, our findings provide preliminary evidence that men age 18+ who are first to arrive experience more hospitalization events in the following 5 years. Future research should explore additional outcomes and whether other gendered migration contexts are related to immigrants’ health

Assessment of quality of life for frail, elderly patients post-ICU discharge: a protocol for a scoping review

Introduction Rises in average life expectancy, increased comorbidities and frailty among older patients lead to higher admission rates to intensive care units (ICU). During an ICU stay, loss of physical and cognitive functions may occur, causing prolonged rehabilitation. Some functions may be lost permanently, affecting quality of life (QoL). There is a lack of understanding regarding how many variables are relevant to health-related outcomes and which outcomes are significant for the QoL of frail, elderly patients following discharge from the ICU. Therefore, this scoping review aims to identify reported variables for health-related outcomes and explore perspectives regarding QoL for this patient group.Methods and analysis The Joanna Briggs Institute guidelines for scoping reviews will be employed and original, peer-reviewed studies in English and Scandinavian languages published from 2013 to 2023 will be included. The search will be conducted from July 2023 to December 2023, according to the inclusion criteria in Embase, MEDLINE, PsycINFO and CINAHL. References to identified studies will be hand-searched, along with backward and forward citation searching for systematic reviews. A librarian will support and qualify the search strategy. Two reviewers will independently screen eligible studies and perform data extraction according to predefined headings. In the event of disagreements, a third reviewer will adjudicate until consensus is achieved. Results will be presented narratively and in table form and discussed in relation to relevant literature.Ethics and dissemination Ethical approval is unnecessary, as the review synthesises existing research. The results will be disseminated through a peer-reviewed publication in a scientific journal