Paternal antisocial behavior and sons' cognitive ability: a population-based quasiexperimental study.

Parents' antisocial behavior is associated with developmental risks for their offspring, but its effects on their children's cognitive ability are unknown. We used linked Swedish register data for a large sample of adolescent men (N = 1,177,173) and their parents to estimate associations between fathers' criminal-conviction status and sons' cognitive ability assessed at compulsory military conscription. Mechanisms behind the association were tested in children-of-siblings models across three types of sibling fathers with increasing genetic relatedness (half-siblings, full siblings, and monozygotic twins) and in quantitative genetic models.

Variability in ADHD care in community-based pediatrics.

Background: Although many efforts have been made to improve the quality of care delivered to children with attention-deficit/hyperactivity disorder (ADHD) in community-based pediatric settings, little is known about typical ADHD care in these settings other than rates garnered through pediatrician self-report.

Methods: Rates of evidence-based ADHD care and sources of variability (practice-level, pediatrician-level, patient-level) were determined by chart reviews of a random sample of 1594 patient charts across 188 pediatricians at 50 different practices. In addition, the associations of Medicaid-status and practice setting (ie, urban, suburban, and rural) with the quality of ADHD care were examined.

Familial confounding of the association between maternal smoking during pregnancy and ADHD in offspring.

Background: Maternal Smoking During Pregnancy (SDP) has consistently been associated with increased risk of attention-deficit/hyperactivity disorder (ADHD) in offspring, but recent studies indicate that this association might be due to unmeasured familial confounding.

Methods: A total of 813,030 individuals born in Sweden between 1992 and 2000 were included in this nationwide population-based cohort study. Data on maternal SDP and ADHD diagnosis were obtained from national registers and patients were followed up from the age of 3 to the end of 2009.

Maternal age at childbirth and risk for ADHD in offspring: a population-based cohort study.

Background: Women who give birth at younger ages (e.g. teenage mothers) are more likely to have children who exhibit behaviour problems, such as attention-deficit/hyperactivity disorder (ADHD).

Codevelopment of ADHD and externalizing behavior from childhood to adulthood.

Background: Attention-Deficit/Hyperactivity Disorder (ADHD) frequently co-occurs with externalizing disorders, but a clear understanding of the etiologic underpinnings is hampered by the limited understanding of the codevelopment of the traits from childhood into early adulthood.

Methods: Using a birth cohort of 2600 twins, the Swedish Twin study of Child and Adolescent Development study, assessed at ages 8-9, 13-14, 16-17, and 19-20, we investigated the codevelopment of ADHD and externalizing behavior from childhood to adulthood. The analyses examined ADHD-like and externalizing traits, as rated by twins and their parents using the Attention Problems scale and Externalizing scale of the Child Behavior Checklist, and estimated cross-lagged effects (one trait at one time-point predicting the other at the next).

Autism spectrum disorders and coexisting disorders in a nationwide Swedish twin study.

Background: Evidence from twin and molecular genetic studies is accumulating that Autism Spectrum Disorder (ASD) shares substantial etiological factors with other disorders. This is mirrored in clinical practice where ASD without coexisting disorders is rare. The present study aims to examine the range of coexisting disorders in ASD in a genetically informative cohort.

Fetal growth and psychiatric and socioeconomic problems: population-based sibling comparison.

Background: It is unclear whether associations between fetal growth and psychiatric and socioeconomic problems are consistent with causal mechanisms.

Aims: To estimate the extent to which associations are a result of unmeasured confounding factors using a sibling-comparison approach.

Method: We predicted outcomes from continuously measured birth weight in a Swedish population cohort (n = 3 291 773), while controlling for measured and unmeasured confounding.

Exposure to air pollution from traffic and neurodevelopmental disorders in Swedish twins.

Background: Recent studies have reported associations between air pollution exposure and neurodevelopmental disorders in children, but the role of pre- and postnatal exposure has not been elucidated.

Aim: We aimed to explore the risk for autism spectrum disorders (ASD) and attention-deficit hyperactivity disorder (ADHD) among children in relation to pre- and postnatal exposure to air pollution from road traffic.

Methods: Parents of 3,426 twins born in Stockholm during 1992-2000 were interviewed, when their children were 9 or 12 years old, for symptoms of neurodevelopmental disorders.

Population-based, multi-generational family clustering study of social anxiety disorder and avoidant personality disorder.

Background: We aimed to provide unbiased estimates of familial risk and heritability of social anxiety disorder (SAD) and avoidant personality disorder (AVPD).

Method: We identified 18 399 individuals diagnosed with SAD and 2673 with AVPD in the Swedish National Patient Register between 1997 and 2009. Risks (odds ratios; OR) for SAD in all biological and non-biological relatives of probands, compared to relatives of unaffected individuals were calculated.

The association between Darier disease, bipolar disorder, and schizophrenia revisited: a population-based family study.

Objectives: Darier disease is an autosomal dominant skin disorder caused by mutations in the ATPase, Ca++ transporting, cardiac muscle, slow twitch 2 (ATP2A2) gene and previously reported to cosegregate with bipolar disorder and schizophrenia in occasional pedigrees. It is, however, unknown whether these associations exist also in the general population, and the objective of this study was to examine this question.

Methods: We compared a national sample of individuals with Darier disease and their first-degree relatives with matched unexposed individuals from the general population and their first-degree relatives, respectively.

Common genetic variants associated with cognitive performance identified using the proxy-phenotype method.

We identify common genetic variants associated with cognitive performance using a two-stage approach, which we call the proxy-phenotype method. First, we conduct a genome-wide association study of educational attainment in a large sample (n = 106,736), which produces a set of 69 education-associated SNPs. Second, using independent samples (n = 24,189), we measure the association of these education-associated SNPs with cognitive performance.

Fixed-effects models and diagnosing psychiatric disorders--reply.

We appreciate having the opportunity to respond to Sonis’ concerns regarding our manuscript on advancing paternal age (APA) at childbearing. It is important to note that the population and within-family estimates respond to different research questions. The population estimates examine how common it is that offspring born to fathers of different ages have psychopathology.

Anabolic androgenic steroids and violent offending: confounding by polysubstance abuse among 10,365 general population men.

Background And Aims: Anabolic androgenic steroid (AAS) use is associated with aggressive and violent behaviour, but it remains uncertain if this relationship is causal in humans. We examined the link between AAS use and violent crime while controlling for polysubstance abuse and additional suggested risk factors for violence.

Design: Cross-sectional study of a population-based sample.

Stimulant ADHD medication and risk for substance abuse.

Background: There are persistent concerns of long-term effects of stimulant ADHD medication on the development of substance abuse.

Methods: Using Swedish national registers, we studied all individuals born between 1960 and 1998 and diagnosed with ADHD (26,249 men and 12,504 women). We investigated the association between stimulant ADHD medication in 2006 and substance abuse during 2009.

Childhood family income, adolescent violent criminality and substance misuse: quasi-experimental total population study.

Background: Low socioeconomic status in childhood is a well-known predictor of subsequent criminal and substance misuse behaviours but the causal mechanisms are questioned. Aims To investigate whether childhood family income predicts subsequent violent criminality and substance misuse and whether the associations are in turn explained by unobserved familial risk factors.

Method: Nationwide Swedish quasi-experimental, family-based study following cohorts born 1989-1993 (n(total) = 526 167, n(cousins) = 262 267, n(siblings) = 216 424) between the ages of 15 and 21 years.

Bipolar disorder and its relation to major psychiatric disorders: a family-based study in the Swedish population.

Objectives: Bipolar disorder (BPD) shares genetic components with other psychiatric disorders; however, uncertainty remains about where in the psychiatric spectra BPD falls. To understand the etiology of BPD, we studied the familial aggregation of BPD and co-aggregation between BPD and schizophrenia, depression, anxiety disorders, attention-deficit hyperactivity disorder, drug abuse, personality disorders, and autism spectrum disorders.

Methods: A population-based cohort was created by linking several Swedish national registers.

Maternal smoking during pregnancy and adverse outcomes in offspring: genetic and environmental sources of covariance.

Maternal smoking during pregnancy (SDP) has been associated with several psychiatric outcomes in the offspring; studies have questioned whether the associations are causal, however. We analyzed all children born in Sweden between 1983 and 2009 to investigate the effect of SDP on multiple indicators of adverse outcomes in three areas: pregnancy outcomes (birth weight, preterm birth and being born small for gestational age), long-term cognitive abilities (low academic achievement and general cognitive ability) and externalizing behaviors (criminal conviction, violent criminal conviction and drug misuse). SDP was associated with all outcomes.

Does population density and neighborhood deprivation predict schizophrenia? A nationwide Swedish family-based study of 2.4 million individuals.

People living in densely populated and socially disorganized areas have higher rates of psychiatric morbidity, but the potential causal status of such factors is uncertain. We used nationwide Swedish longitudinal registry data to identify all children born 1967-1989 (n = 2361585), including separate datasets for all cousins (n = 1715059) and siblings (n = 1667894). The nature of the associations between population density and neighborhood deprivation and individual risk for a schizophrenia diagnosis was investigated while adjusting for unobserved familial risk factors (through cousin and sibling comparisons) and then compared with similar associations for depression.

Hypospadias and increased risk for neurodevelopmental disorders.

Background: Hypospadias (aberrant opening of the urethra on the underside of the penis) occurs in 1 per 300 newborn boys. It has been previously unknown whether this common malformation is associated with increased psychiatric morbidity later in life. Studies of individuals with hypospadias also provide an opportunity to examine whether difference in androgen signaling is related to neurodevelopmental disorders.

Birth weight as an independent predictor of ADHD symptoms: a within-twin pair analysis.

Background: Studies have found an association between low birth weight and ADHD, but the nature of this relation is unclear. First, it is uncertain whether birth weight is associated with both of the ADHD dimensions, inattentiveness and hyperactivity-impulsivity. Second, it remains uncertain whether the association between birth weight and ADHD symptom severity is confounded by familial factors.

Applying polygenic risk scores to postpartum depression.

The etiology of major depressive disorder (MDD) is likely to be heterogeneous, but postpartum depression (PPD) is hypothesized to represent a more homogenous subset of MDD. We use genome-wide SNP data to explore this hypothesis. We assembled a total cohort of 1,420 self-report cases of PPD and 9,473 controls with genome-wide genotypes from Australia, The Netherlands, Sweden and the UK.