Modeling Etiology of Smoking During Pregnancy in Swedish Twins, Full-, and Half-Siblings, Reared Together and Apart

The Swedish military conscription register: opportunities for its use in medical research

In Sweden, conscription around age 18y was mandatory for young men until June 30, 2010. From July 1, 2017, it became mandatory again for both sexes but the proportion of summoned people for standardised testing has so far been low. This paper describes the history, structure and content of the Swedish Military Conscription Register (SMCR). We retrieved information about the SMCR from written sources and through e-mail interviews with key personnel at the Swedish Defence Conscription and Assessment Agency. We also analysed data from the SMCR between 1969 and 2018. Between 1969 and 2018 the SMCR contains digital data on approximately 2 million individuals (98.6% men). Most conscripts were born between 1951 and 1988 (n = 1,900,000; tested between 1969 and 2006). For the 1951-1987 birth cohorts, the register has a population coverage of approximately 90% for men. Conscripts underwent written tests focusing on verbal, spatial, logical and technical ability, medical, physical, and psychological tests. The medical assessment included hearing, vision, muscle and exercise capacity, height, weight, blood pressure and resting heart rate. The SMCR has been widely used to study, e.g., obesity, cardiovascular disease, mental health, crime, cardiovascular fitness, muscle strength, sick leave and disability pension. Severe disease could qualify for exemption from military service. Thus, the prevalence of such diseases is underestimated in the SMCR population. Between 1990 and 2018, about 25,000 women also volunteered for testing. The SMCR contains population-based data on physical and psychological health in about 90% of all men born between 1951 and 1987 (corresponding to testing between 1969 and 2006), and can be used to address a host of research questions.

The patterns of family genetic risk scores for eleven major psychiatric and substance use disorders in a Swedish national sample

To clarify the structure of genetic risks for 11 major psychiatric disorders, we calculated, from morbidity risks for disorders in 1st-5th degree relatives controlling for cohabitation effects, in the Swedish population born between 1932 and 1995 (n = 5,830,014), the family genetic risk scores (FGRS) for major depression (MD), anxiety disorders (AD), obsessive-compulsive disorder (OCD), bipolar disorder (BD), schizophrenia (SZ), bulimia (BUL), anorexia nervosa (AN), alcohol use disorder (AUD), drug use disorder (DUD), ADHD, and autism-spectrum disorder (ASD). For all affected individuals, we calculated their mean standardized FGRS for each disorder. The patterns of FGRS were quite similar for MD and AD, and for AUD and DUD, but substantially less similar for BUL and AN, BD and SZ, and ADHD and ASD. While OCD had high levels of FGRS for MD and AD, the overall FGRS profile differed considerably from MD and AD. ADHD FGRS scores were substantially elevated in AUD and DUD. FGRS scores for BD, OCD, AN, ASD, ADHD, and especially SZ were relatively disorder-specific while genetic risk for MD and AD had more generalized effects. The levels of FGRS for BMI, coronary artery disease, and educational attainment across our disorders replicated prior associations found using molecular genetic methods. All diagnostic categories examined had elevated FGRS for many disorders producing, for each condition, an informative FGRS profile. Using a novel method which approximates, from pedigree data, aggregate genetic risk, we have replicated and extended prior insights into the structure of genetic risk factors for key psychiatric illnesses.