Intellectual disability (ID) has been linked to substance use-related problems (SUP). However, previous research is limited by the small sample sizes, lack of general population comparison and have not accounted for familial confoundings. The role of other psychiatric comorbidities also remains unknown.

To examine the risk of SUP in individuals with mild-ID and assess whether the associations depend on other psychiatric comorbidities, controlling for potential familial confounding.

Population-based cohort study of individuals born in Sweden 1973-2003. We identified 19,078 individuals with mild-ID, 953,900 reference individuals from the general population, and 20,722 full-siblings of individuals with mild-ID. Conditional logistic regression models were used to compare individuals with mild-ID to the general population and their full-siblings regarding the risk of SUP, including alcohol and substance use disorders, alcohol and substance-related somatic diseases, substance-related crime, and substance-related death. Analyses were repeated stratified by the presence of psychiatric comorbidities.

Individuals with mild-ID had increased risks of any SUP (adjusted OR [95%CI]: 1.41 [1.35, 1.47]), compared to the general population, including alcohol-related somatic diseases (3.27 [1.92, 5.59]), alcohol (2.05 [1.91, 2.22]) and drug-use disorder (1.79 [1.69, 1.91]), and alcohol (1.36 [1.19, 1.49]) and drug-related crime (1.27 [1.19, 1.36]). The risk of SUP for individuals with mild ID was particularly elevated with comorbid mood (3.74 [3.47, 4.04]), anxiety (3.30 [3.09, 3.53]) and attention-deficit/hyperactivity disorders (2.61 [2.44, 2.80]). Increased risk of SUP remained significant when controlling for familial confounding.

Individuals with mild-ID, especially those with other psychiatric comorbidities, are at increased risks of SUP.

No significant relationships.

Even though 0.3-0.8% percent of the male population are born with hypospadias, it is not known if this is associated with an increased risk for psychiatric morbidity later in life.

The aim of this study was to assess the association between hypospadias and risk of psychiatric disorders in affected individuals.

The association between hypospadias and psychiatric disorders was examined in a population-based cohort study using Swedish registers. Individuals born in Sweden between 1973 and 2009 were included in the study. Among them, 11,156 patients with hypospadias were identified and matched with 1,098,714 distinct controls by year of birth and county. The following outcomes were evaluated: 1- suicide attempt, 2- psychotic, 3- mood, 4-anxiety, 5- eating, 6- personality disorders, 7- disorders due to psychoactive substance use, 8- ADHD, 9- pervasive developmental disorders, 10- intellectual disabilities, and 11- other childhood emotional disorders.

After adjusting for socio-economic and perinatal factors, malformations and/or genetic syndromes, patients with hypospadias were more likely to be diagnosed with pervasive developmental disorders (OR 1.4; 95% CI 1.1-1.6), intellectual disabilities (OR 1.8; 95% CI 1.6-2.1), ADHD (OR 1.2; 95% CI 1.0-1.4) and other childhood emotional disorders (OR 1.3; 95% CI 1.1-1.4) compared to the controls. No relation between other psychiatric diagnosis and hypospadias was found.

Hypospadias is associated with an increased risk of neurodevelopmental disorders.

Studies on the individual gender-specific risk and familial co-aggregation of suicidal behaviour in autism spectrum disorder (ASD) are lacking.

We conducted a matched case-cohort study applying conditional logistic regression models on 54 168 individuals recorded in 1987–2013 with ASD in Swedish national registers: ASD without ID n = 43 570 (out of which n = 19035, 43.69% with ADHD); ASD + ID n = 10 598 (out of which n = 2894 individuals, 27.31% with ADHD), and 270 840 controls, as well as 347 155 relatives of individuals with ASD and 1 735 775 control relatives.

The risk for suicidal behaviours [reported as odds ratio OR (95% confidence interval CI)] was most increased in the ASD without ID group with comorbid ADHD [suicide attempt 7.25 (6.79–7.73); most severe attempts i.e. requiring inpatient stay 12.37 (11.33–13.52); suicide 13.09 (8.54–20.08)]. The risk was also increased in ASD + ID group [all suicide attempts 2.60 (2.31–2.92); inpatient only 3.45 (2.96–4.02); suicide 2.31 (1.16–4.57)]. Females with ASD without ID had generally higher risk for suicidal behaviours than males, while both genders had highest risk in the case of comorbid ADHD [females, suicide attempts 10.27 (9.27–11.37); inpatient only 13.42 (11.87–15.18); suicide 14.26 (6.03–33.72); males, suicide attempts 5.55 (5.10–6.05); inpatient only 11.33 (9.98–12.86); suicide 12.72 (7.77–20.82)]. Adjustment for psychiatric comorbidity attenuated the risk estimates. In comparison to controls, relatives of individuals with ASD also had an increased risk of suicidal behaviour.

Clinicians treating patients with ASD should be vigilant for suicidal behaviour and consider treatment of psychiatric comorbidity.

Most studies underline the contribution of heritable factors for psychiatric disorders. However, heritability estimates depend on the population under study, diagnostic instruments, and study designs that each has its inherent assumptions, strengths, and biases. We aim to test the homogeneity in heritability estimates between two powerful, and state of the art study designs for eight psychiatric disorders.

We assessed heritability based on data of Swedish siblings (N = 4 408 646 full and maternal half-siblings), and based on summary data of eight samples with measured genotypes (N = 125 533 cases and 208 215 controls). All data were based on standard diagnostic criteria. Eight psychiatric disorders were studied: (1) alcohol dependence (AD), (2) anorexia nervosa, (3) attention deficit/hyperactivity disorder (ADHD), (4) autism spectrum disorder, (5) bipolar disorder, (6) major depressive disorder, (7) obsessive-compulsive disorder (OCD), and (8) schizophrenia.

Heritability estimates from sibling data varied from 0.30 for Major Depression to 0.80 for ADHD. The estimates based on the measured genotypes were lower, ranging from 0.10 for AD to 0.28 for OCD, but were significant, and correlated positively (0.19) with national sibling-based estimates. When removing OCD from the data the correlation increased to 0.50.

Given the unique character of each study design, the convergent findings for these eight psychiatric conditions suggest that heritability estimates are robust across different methods. The findings also highlight large differences in genetic and environmental influences between psychiatric disorders, providing future directions for etiological psychiatric research.

Many studies have addressed the question of whether mental disorder is associated with creativity, but high-quality epidemiological evidence has been lacking.

To test for an association between studying a creative subject at high school or university and later mental disorder.

In a case–control study using linked population-based registries in Sweden (N = 4 454 763), we tested for associations between tertiary education in an artistic field and hospital admission with schizophrenia (N = 20 333), bipolar disorder (N = 28 293) or unipolar depression (N = 148 365).

Compared with the general population, individuals with an artistic education had increased odds of developing schizophrenia (odds ratio = 1.90, 95% CI = [1.69; 2.12]) bipolar disorder (odds ratio = 1.62 [1.50; 1.75]) and unipolar depression (odds ratio = 1.39 [1.34; 1.44]. The results remained after adjustment for IQ and other potential confounders.

Students of artistic subjects at university are at increased risk of developing schizophrenia, bipolar disorder and unipolar depression in adulthood.

None.

Associations between parenting and child outcomes are often interpreted as reflecting causal, social influences. However, such associations may be confounded by genes common to children and their biological parents. To the extent that these shared genes influence behaviours in both generations, a passive genetic mechanism may explain links between them. Here we aim to quantify the relative importance of passive genetic v. social mechanisms in the intergenerational association between parent–offspring relationship quality and offspring internalizing problems in adolescence.

We used a Children-of-Twins (CoT) design with data from the parent-based Twin and Offspring Study of Sweden (TOSS) sample [909 adult twin pairs and their offspring; offspring mean age 15.75 (2.42) years], and the child-based Swedish Twin Study of CHild and Adolescent Development (TCHAD) sample [1120 adolescent twin pairs; mean age 13.67 (0.47) years]. A composite of parent-report measures (closeness, conflict, disagreements, expressions of affection) indexed parent–offspring relationship quality in TOSS, and offspring self-reported internalizing symptoms were assessed using the Child Behavior Checklist (CBCL) in both samples.

A social transmission mechanism explained the intergenerational association [r = 0.21 (0.16–0.25)] in our best-fitting model. A passive genetic transmission pathway was not found to be significant, indicating that parental genetic influences on parent–offspring relationship quality and offspring genetic influences on their internalizing problems were non-overlapping.

These results indicate that this intergenerational association is a product of social interactions between children and parents, within which bidirectional effects are highly plausible. Results from genetically informative studies of parenting-related effects should be used to help refine early parenting interventions aimed at reducing risk for psychopathology.

Universal screening for postpartum depression is recommended in many countries. Knowledge of whether the disclosure of depressive symptoms in the postpartum period differs across cultures could improve detection and provide new insights into the pathogenesis. Moreover, it is a necessary step to evaluate the universal use of screening instruments in research and clinical practice. In the current study we sought to assess whether the Edinburgh Postnatal Depression Scale (EPDS), the most widely used screening tool for postpartum depression, measures the same underlying construct across cultural groups in a large international dataset.

Ordinal regression and measurement invariance were used to explore the association between culture, operationalized as education, ethnicity/race and continent, and endorsement of depressive symptoms using the EPDS on 8209 new mothers from Europe and the USA.

Education, but not ethnicity/race, influenced the reporting of postpartum depression [difference between robust comparative fit indexes (∆*CFI) < 0.01]. The structure of EPDS responses significantly differed between Europe and the USA (∆*CFI > 0.01), but not between European countries (∆*CFI < 0.01).

Investigators and clinicians should be aware of the potential differences in expression of phenotype of postpartum depression that women of different educational backgrounds may manifest. The increasing cultural heterogeneity of societies together with the tendency towards globalization requires a culturally sensitive approach to patients, research and policies, that takes into account, beyond rhetoric, the context of a person's experiences and the context in which the research is conducted.

Advanced paternal age at childbirth is associated with psychiatric disorders in offspring, including schizophrenia, bipolar disorder and autism. However, few studies have investigated paternal age's relationship with eating disorders in offspring. In a large, population-based cohort, we examined the association between paternal age and offspring eating disorders, and whether that association remains after adjustment for potential confounders (e.g. parental education level) that may be related to late/early selection into fatherhood and to eating disorder incidence.

Data for 2 276 809 individuals born in Sweden 1979–2001 were extracted from Swedish population and healthcare registers. The authors used Cox proportional hazards models to examine the effect of paternal age on the first incidence of healthcare-recorded anorexia nervosa (AN) and all eating disorders (AED) occurring 1987–2009. Models were adjusted for sex, birth order, maternal age at childbirth, and maternal and paternal covariates including country of birth, highest education level, and lifetime psychiatric and criminal history.

Even after adjustment for covariates including maternal age, advanced paternal age was associated with increased risk, and younger paternal age with decreased risk, of AN and AED. For example, the fully adjusted hazard ratio for the 45+ years (v. the 25–29 years) paternal age category was 1.32 [95% confidence interval (CI) 1.14–1.53] for AN and 1.26 (95% CI 1.13–1.40) for AED.

In this large, population-based cohort, paternal age at childbirth was positively associated with eating disorders in offspring, even after adjustment for potential confounders. Future research should further explore potential explanations for the association, including de novo mutations in the paternal germline.

Prior studies suggest parental and perinatal risk factors are associated with later offending. It remains uncertain, however, if such risk factors are similarly related to sexual offending.

We linked socio-demographic, family relations, and perinatal (obtained at birth) data from the nationwide Swedish registers from 1973 to 2009 with information on criminal convictions of cases and control subjects. Male sex offenders (n = 13 773) were matched 1:5 on birth year and county of birth in Sweden to male controls without sexual or non-sexual violent convictions. To examine risk-factor specificity for sexual offending, we also compared male violent, non-sexual offenders (n = 135 953) to controls without sexual or non-sexual violent convictions. Predictors included parental (young maternal or paternal age at son's birth, educational attainment, violent crime, psychiatric disorder, substance misuse, suicide attempt) and perinatal (number of older brothers, low Apgar score, low birth weight, being small for gestational age, congenital malformations, small head size) variables.

Conditional logistic regression models found consistent patterns of statistically significant, small to moderate independent associations of parental risk factors with sons’ sexual offending and non-sexual violent offending. For perinatal risk factors, patterns varied more; small for gestational age and small head size exhibited similar risk effects for both offence types whereas a higher number of older biological brothers and any congenital malformation were small, independent risk factors only for non-sexual violence.

This nationwide study suggests substantial commonalities in parental and perinatal risk factors for the onset of sexual and non-sexual violent offending.

Self-harm among young adults is a common and increasing phenomenon in many parts of the world. The long-term prognosis after self-harm at young age is inadequately known. We aimed to estimate the risk of mental illness and suicide in adult life after self-harm in young adulthood and to identify prognostic factors for adverse outcome.

We conducted a national population-based matched case-cohort study. Patients aged 18-24 years (n = 13 731) hospitalized after self-harm between 1990 and 2003 and unexposed individuals of the same age (n = 137 310 ) were followed until December 2009. Outcomes were suicide, psychiatric hospitalization and psychotropic medication in short-term (1-5 years) and long-term (>5 years) follow-up.

Self-harm implied an increased relative risk of suicide during follow-up [hazard ratio (HR) 16.4, 95% confidence interval (CI) 12.9–20.9). At long-term follow-up, 20.3% had psychiatric hospitalizations and 51.1% psychotropic medications, most commonly antidepressants and anxiolytics. There was a six-fold risk of psychiatric hospitalization (HR 6.3, 95% CI 5.8–6.8) and almost three-fold risk of psychotropic medication (HR 2.8, 95% CI 2.7–3.0) in long-term follow-up. Mental disorder at baseline, especially a psychotic disorder, and a family history of suicide were associated with adverse outcome among self-harm patients.

We found highly increased risks of future mental illness and suicide among young adults after self-harm. A history of a mental disorder was an important indicator of long-term adverse outcome. Clinicians should consider the substantially increased risk of suicide among self-harm patients with psychotic disorders.

Advancing paternal age has been linked to psychiatric disorders. These associations might be caused by the increased number of de novo mutations transmitted to offspring of older men. It has also been suggested that the associations are confounded by a genetic liability for psychiatric disorders in parents. The aim of this study was to indirectly test the confounding hypotheses by examining if there is a genetic component to advancing paternal age and if men with a genetic liability for psychiatric disorders have children at older ages.

We examined the genetic component to advancing paternal age by utilizing the twin model in a cohort of male twins (N = 14 679). We also studied ages at childbirth in men with or without schizophrenia, bipolar disorder and/or autism spectrum disorder. Ages were examined in: (1) healthy men, (2) affected men, (3) healthy men with an affected sibling, (4) men with healthy spouses, (5) men with affected spouses, and (6) men with healthy spouses with an affected sibling.

The twin analyses showed that late fatherhood is under genetic influence (heritability = 0.33). However, affected men or men with affected spouses did not have children at older ages. The same was found for healthy individuals with affected siblings. Instead, these men were generally having children at younger ages.

Although there is a genetic component influencing late fatherhood, our data suggest that the associations are not explained by psychiatric disorders or a genetic liability for psychiatric disorders in the parent.

Twin studies have been criticized for upwardly biased estimates that might contribute to the missing heritability problem.

We identified, from the general Swedish population born 1960–1990, informative sibships containing a proband, one reared-together full- or half-sibling and a full-, step- or half-sibling with varying degrees of childhood cohabitation with the proband. Estimates of genetic, shared and individual specific environment for drug abuse (DA), alcohol use disorder (AUD) and criminal behavior (CB), assessed from medical, legal or pharmacy registries, were obtained using Mplus.

Aggregate estimates of additive genetic effects for DA, AUD and CB obtained separately in males and females varied from 0.46 to 0.73 and agreed with those obtained from monozygotic and dizygotic twins from the same population. Of 54 heritability estimates from individual classes of informative sibling trios (3 syndromes × 9 classes of trios × 2 sexes), heritability estimates from the siblings were lower, tied and higher than those from obtained from twins in 26, one and 27 comparisons, respectively. By contrast, of 54 shared environmental estimates, 33 were lower than those found in twins, one tied and 20 were higher.

With adequate information, human populations can provide many methods for estimating genetic and shared environmental effects. For the three externalizing syndromes examined, concerns that heritability estimates from twin studies are upwardly biased or were not generalizable to more typical kinds of siblings were not supported. Overestimation of heritability from twin studies is not a likely explanation for the missing heritability problem.

Major depressive disorder (MDD) is moderately heritable, however genome-wide association studies (GWAS) for MDD, as well as for related continuous outcomes, have not shown consistent results. Attempts to elucidate the genetic basis of MDD may be hindered by heterogeneity in diagnosis. The Center for Epidemiological Studies Depression (CES-D) scale provides a widely used tool for measuring depressive symptoms clustered in four different domains which can be combined together into a total score but also can be analysed as separate symptom domains.

We performed a meta-analysis of GWAS of the CES-D symptom clusters. We recruited 12 cohorts with the 20- or 10-item CES-D scale (32 528 persons).

One single nucleotide polymorphism (SNP), rs713224, located near the brain-expressed melatonin receptor (MTNR1A) gene, was associated with the somatic complaints domain of depression symptoms, with borderline genome-wide significance (pdiscovery = 3.82 × 10−8). The SNP was analysed in an additional five cohorts comprising the replication sample (6813 persons). However, the association was not consistent among the replication sample (pdiscovery+replication = 1.10 × 10−6) with evidence of heterogeneity.

Despite the effort to harmonize the phenotypes across cohorts and participants, our study is still underpowered to detect consistent association for depression, even by means of symptom classification. On the contrary, the SNP-based heritability and co-heritability estimation results suggest that a very minor part of the variation could be captured by GWAS, explaining the reason of sparse findings.

Given the frequency with which families change residences, the effects of childhood relocations have gained increasing research attention. Many researchers have demonstrated that childhood relocations are associated with a variety of adverse outcomes. However, drawing strong causal claims remains problematic due to uncontrolled confounding factors.

We utilized longitudinal, population-based Swedish registers to generate a nationally representative sample of offspring born 1983–1997 (n = 1 510 463). Using Cox regression and logistic regression, we examined the risk for numerous adverse outcomes after childhood relocation while controlling for measured covariates. To account for unmeasured genetic and environmental confounds, we also compared differentially exposed cousins and siblings.

In the cohort baseline model, each annual relocation was associated with risk for the adverse outcomes, including suicide attempt [hazard ratio (HR) 1.19, 95% confidence interval (CI) 1.19–1.20]. However, when accounting for offspring and parental covariates (HR 1.08, 95% CI 1.07–1.09), as well as genetic and environmental confounds shared by cousins (HR 1.07, 95% CI 1.05–1.09) and siblings (HR 1.00, 95% CI 0.97–1.04), the risk for suicide attempt attenuated. We found a commensurate pattern of results for severe mental illness, substance abuse, criminal convictions, and low academic achievement.

Previous research may have overemphasized the independent association between relocations and later adverse outcomes. The results suggest that the association between childhood relocations and suicide attempt, psychiatric problems, and low academic achievement is partially explained by genetic and environmental confounds correlated with relocations. This study demonstrates the importance of using family-based, quasi-experimental designs to test plausible alternate hypotheses when examining causality.