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This genetic association study assesses data from a case-cohort sample of individuals born in Denmark to provide population-based estimates of prevalence and risk associated with psychiatric disorders for recurrent copy number variants. Key Points: Question: What is the population-based prevalence and psychiatric risk associated with recurrent copy number variants (rCNVs) and how do they differ across outcomes and rCNVs? Findings: In a genetic association study of the Danish population born in 1981-2008 and followed up until 2015, most rCNV risk profiles were similar across autism, attention-deficit/hyperactivity disorder, and schizophrenia. The magnitude of risk increase correlated with locus size and gene constraint but did not differ between deletions and duplications. Meaning: Several rCNVs were more prevalent and conferred less risk of psychiatric disorders than estimated previously, which highlights the importance of population-based estimates for implementing genetics-based prediction in health care. Importance: Recurrent copy number variants (rCNVs) have been associated with increased risk of psychiatric disorders in case-control studies, but their population-level impact is unknown. Objective: To provide unbiased population-based estimates of prevalence and risk associated with psychiatric disorders for rCNVs and to compare risks across outcomes, rCNV dosage type (deletions or duplications), and locus features. Design, Setting, and Participants: This genetic association study is an analysis of data from the Lundbeck Foundation Initiative for Integrative Psychiatric Research (iPSYCH) case-cohort sample of individuals born in Denmark in 1981-2008 and followed up until 2015, including (1) all individuals (n = 92 531) with a hospital discharge diagnosis of attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), bipolar disorder, major depressive disorder (MDD), or schizophrenia spectrum disorder (SSD) and (2) a subcohort (n = 50 625) randomly drawn from the source population. Data were analyzed from January 2021 to August 2023. Exposures: Carrier status of deletions and duplications at 27 autosomal rCNV loci was determined from neonatal blood samples genotyped on single-nucleotide variant microarrays. Main Outcomes and Measures: Population-based rCNV prevalence was estimated with a survey model using finite population correction to account for oversampling of cases. Hazard ratio (HR) estimates and 95% CIs for psychiatric disorders were derived using weighted Cox proportional hazard models. Risks were compared across outcomes, dosage type, and locus features using generalized estimating equation models. Results: A total of 3547 rCNVs were identified in 64 735 individuals assigned male at birth (53.8%) and 55 512 individuals assigned female at birth (46.2%) whose age at the end of follow-up ranged from 7.0 to 34.7 years (mean, 21.8 years). Most observed increases in rCNV-associated risk for ADHD, ASD, or SSD were moderate, and risk estimates were highly correlated across these disorders. Notable exceptions included high ASD-associated risk observed for Prader-Willi/Angelman syndrome duplications (HR, 20.8; 95% CI, 7.9-55). No rCNV was associated with increased MDD risk. Also, rCNV-associated risk was positively correlated with locus size and gene constraint but not with dosage type. Comparison with published case-control and community-based studies revealed a higher prevalence of deletions and lower associated increase in risk for several rCNVs in iPSYCH2015. Conclusions and Relevance: This study found that several rCNVs were more prevalent and conferred less risk of psychiatric disorders than estimated previously. Most case-control studies overestimate rCNV-associated risk of psychiatric disorders, likely because of selection bias. In an era where genetics is increasingly being clinically applied, these results highlight the importance of population-based risk estimates for genetics-based predictions. [ABSTRACT FROM AUTHOR]

Background: Although several types of risk factors for anorexia nervosa (AN) have been identified, including birth-related factors, somatic, and psychosocial risk factors, their interplay with genetic susceptibility remains unclear. Genetic and epidemiological interplay in AN risk were examined using data from Danish nationwide registers. AN polygenic risk score (PRS) and risk factor associations, confounding from AN PRS and/or parental psychiatric history on the association between the risk factors and AN risk, and interactions between AN PRS and each level of target risk factor on AN risk were estimated. Methods: Participants were individuals born in Denmark between 1981 and 2008 including nationwide-representative data from the iPSYCH2015, and Danish AN cases from the Anorexia Nervosa Genetics Initiative and Eating Disorder Genetics Initiative cohorts. A total of 7003 individuals with AN and 45 229 individuals without a registered AN diagnosis were included. We included 22 AN risk factors from Danish registers. Results: Risk factors showing association with PRS for AN included urbanicity, parental ages, genitourinary tract infection, and parental socioeconomic factors. Risk factors showed the expected association to AN risk, and this association was only slightly attenuated when adjusted for parental history of psychiatric disorders or/and for the AN PRS. The interaction analyses revealed a differential effect of AN PRS according to the level of the following risk factors: sex, maternal age, genitourinary tract infection, C-section, parental socioeconomic factors and psychiatric history. Conclusions: Our findings provide evidence for interactions between AN PRS and certain risk-factors, illustrating potential diverse risk pathways to AN diagnosis. [ABSTRACT FROM AUTHOR]

Background Human immunodeficiency virus (HIV) infection is associated with depression. However, previous studies have not addressed familial factors. Methods Nationwide, population-based, matched cohort study of people with HIV (PWH) in Denmark between 1995 and 2021 who were matched on sex and date of birth with a comparison cohort randomly selected from the Danish population. Family-related factors were examined by inclusion of siblings of those in the cohorts. We calculated hazard ratios (HRs) for depression, receipt of antidepressants, electroconvulsive therapy (ECT), and suicide, as well as the yearly proportions of study cohorts with psychiatric hospital contact due to depression and receipt of antidepressants from 10 years before to 10 years after study inclusion. Results We included 5943 PWH and 59 430 comparison cohort members. Median age was 38 years, and 25% were women. We observed an increased risk of depression, receipt of antidepressants, ECT, and suicide among PWH in the 2 first years of observation (HR, 3.3; 95% confidence interval [CI]: 2.5–4.4), HR, 3.0 (95% CI: 2.7–3.4), HR, 2.8 (95% CI:.9–8.6), and HR, 10.7 (95% CI: 5.2–22.2), thereafter the risk subsided but remained increased. The proportions of PWH with psychiatric hospital contact due to depression and receipt of antidepressants were increased prior to and especially after HIV diagnosis. Risk of all outcomes was substantially lower among siblings of PWH than among PWH (HR for receipt of antidepressants, 1.1; 95% CI: 1.0–1.2). Conclusions PWH have an increased risk of depression. Family-related factors are unlikely to explain this risk. [ABSTRACT FROM AUTHOR]

Proportional hazards models have been proposed to analyse time-to-event phenotypes in genome-wide association studies (GWAS). However, little is known about the ability of proportional hazards models to identify genetic associations under different generative models and when ascertainment is present. Here we propose the age-dependent liability threshold (ADuLT) model as an alternative to a Cox regression based GWAS, here represented by SPACox. We compare ADuLT, SPACox, and standard case-control GWAS in simulations under two generative models and with varying degrees of ascertainment as well as in the iPSYCH cohort. We find Cox regression GWAS to be underpowered when cases are strongly ascertained (cases are oversampled by a factor 5), regardless of the generative model used. ADuLT is robust to ascertainment in all simulated scenarios. Then, we analyse four psychiatric disorders in iPSYCH, ADHD, Autism, Depression, and Schizophrenia, with a strong case-ascertainment. Across these psychiatric disorders, ADuLT identifies 20 independent genome-wide significant associations, case-control GWAS finds 17, and SPACox finds 8, which is consistent with simulation results. As more genetic data are being linked to electronic health records, robust GWAS methods that can make use of age-of-onset information will help increase power in analyses for common health outcomes. Robust genome-wide association study (GWAS) methods that can utilise time-to-event information such as age-of-onset will help increase power in analyses for common health outcomes. Here, the authors propose a computationally efficient time-to-event model for GWAS. [ABSTRACT FROM AUTHOR]

The authors investigated associations between polygenic liabilities for bipolar disorder, major depression, and schizophrenia and episode polarity among individuals with bipolar disorder. The sample consisted of 2,705 individuals diagnosed with bipolar disorder at Danish psychiatric hospitals between January 1995 and March 2017. DNA was obtained from dried blood spots collected at birth as part of routine screening. Polygenic risk scores (PRSs) for bipolar disorder, major depression, and schizophrenia were generated using a meta-PRS method combining internally and externally trained components. Associations between PRS and polarity at first episode, polarity at any episode, and number of episodes with a given polarity were evaluated for each disorder-specific PRS using logistic and negative binominal regressions adjusted for the other two PRSs, age, sex, genotype platform, and five ancestral principal components. PRS for bipolar disorder was positively associated with any manic episodes (odds ratio=1.23, 95% CI=1.09–1.38). PRS for depression was positively associated with any depressive (odds ratio=1.11, 95% CI=1.01–1.23) and mixed (odds ratio=1.15, 95% CI=1.03–1.28) episodes and negatively associated with any manic episodes (odds ratio=0.76, 95% CI=0.69–0.84). PRS for schizophrenia was positively associated with any manic episodes (odds ratio=1.13, 95% CI=1.01–1.27), but only when psychotic symptoms were present (odds ratio for psychotic mania: 1.27, 95% CI=1.05–1.54; odds ratio for nonpsychotic mania: 1.06, 95% CI=0.93–1.20). These patterns were similar for first-episode polarity and for the number of episodes within each pole. PRSs for bipolar disorder, major depression, and schizophrenia are associated with episode polarity and psychotic symptoms in a congruent manner among individuals with bipolar disorder. [ABSTRACT FROM AUTHOR]

Poor school performance is linked to higher risks of self-harm. The association might be explained through genetic liabilities for depression or educational attainment. We investigated the association between school performance and self-harm in a population-based sample while assessing the potential influence of polygenic risk scores (PRSs) for depression (PRSMDD) and for educational attainment (PRSEDU). We conducted a follow-up study of individuals born 1987–98 and followed from age 18 until 2016. The total sample consisted of a case group (23,779 diagnosed with mental disorders; schizophrenia, bipolar disorder, depression, autism, and attention deficit hyperactivity disorder (ADHD) and a randomly sampled comparison group (n = 10,925). Genome-wide data were obtained from the Neonatal Screening Biobank and information on school performance, family psychiatric history, and socioeconomic status from national administrative registers. Individuals in the top PRSMDD decile were at higher self-harm risk in the case group (IRR: 1.30; 95% CI 1.15–1.46), whereas individuals in the top PRSEDU decile were at lower self-harm risk (IRR: 0.63; 95% CI: 0.55–0.74). Poorer school performance was associated with higher self-harm risk in persons diagnosed with any mental disorder (IRR: 1.69; 95% CI: 1.44–1.99) and among the comparison group (IRR: 7.93; 95% CI: 4.47–15.18). Observed effects of PRSMDD and PRSEDU on self-harm risk were strongest for individuals with poor school performance. Associations between PRSMDD and self-harm risk and between PRSEDU and self-harm risk were found. Nevertheless, these polygenic scores seem currently of limited clinical utility for identifying individuals at high self-harm risk. [ABSTRACT FROM AUTHOR]

Background: In this study, we examined the relationship between polygenic liability for depression and number of stressful life events (SLEs) as risk factors for early-onset depression treated in inpatient, outpatient or emergency room settings at psychiatric hospitals in Denmark. Methods: Data were drawn from the iPSYCH2012 case-cohort sample, a population-based sample of individuals born in Denmark between 1981 and 2005. The sample included 18 532 individuals who were diagnosed with depression by a psychiatrist by age 31 years, and a comparison group of 20 184 individuals. Information on SLEs was obtained from nationwide registers and operationalized as a time-varying count variable. Hazard ratios and cumulative incidence rates were estimated using Cox regressions. Results: Risk for depression increased by 35% with each standard deviation increase in polygenic liability (p < 0.0001), and 36% (p < 0.0001) with each additional SLE. There was a small interaction between polygenic liability and SLEs (β = −0.04, p = 0.0009). The probability of being diagnosed with depression in a hospital-based setting between ages 15 and 31 years ranged from 1.5% among males in the lowest quartile of polygenic liability with 0 events by age 15, to 18.8% among females in the highest quartile of polygenic liability with 4+ events by age 15. Conclusions: These findings suggest that although there is minimal interaction between polygenic liability and SLEs as risk factors for hospital-treated depression, combining information on these two important risk factors could potentially be useful for identifying high-risk individuals. [ABSTRACT FROM AUTHOR]

Hernias are characterized by protrusion of an organ or tissue through its surrounding cavity and often require surgical repair. In this study we identify 65,492 cases for five hernia types in the UK Biobank and perform genome-wide association study scans for these five types and two combined groups. Our results show associated variants in all scans. Inguinal hernia has the most associations and we conduct a follow-up study with 23,803 additional cases from four study groups giving 84 independently associated variants. Identified variants from all scans are collapsed into 81 independent loci. Further testing shows that 26 loci are associated with more than one hernia type, suggesting substantial overlap between the underlying genetic mechanisms. Pathway analyses identify several genes with a strong link to collagen and/or elastin (ADAMTS6, ADAMTS16, ADAMTSL3, LOX, ELN) in the vicinity of associated loci for inguinal hernia, which substantiates an essential role of connective tissue morphology. Hernias involve protrusion of an organ or tissue through its surrounding cavity. Here the authors carry out GWAS for five types of hernia and find 81 variants, most of which are associated with inguinal hernia; downstream analysis suggests an important role for connective tissue morphology. [ABSTRACT FROM AUTHOR]

Objective: Information on mental disorders over time is critical for documenting changes in population burden, and aiding understanding of potential causal and non‐causal factors. The aim of this study was to provide temporal changes in the sex‐ and age‐specific incidence rates (IR) of mental disorders diagnosed in Danish hospitals during five decades and investigate whether such changes may be attributable to changes in administrative reporting practice. Methods: This population‐based cohort study included all people living in Denmark between 1970 and 2016. Mental disorders diagnoses were obtained from the Danish Psychiatric Central Research Register. We estimated the IR of each mental disorder (all persons, and sex‐ and age‐specific IRs) and examined the impact of two administrative changes. Results: Our study included 9 107 157 people, followed for 233.0 million person‐years. During follow‐up, 9.5% were diagnosed with at least one mental disorder. The IR for any mental disorder was 39.0 per 10,000 person‐years. Despite fluctuations, this increased between 1970–84 and 2005–2016, from 28.9 to 63.0 per 10,000 person‐years. Increases were most pronounced for younger age groups. Administrative changes did appear to influence incidence rates. Conclusion: Mental disorder IRs have increased in Denmark since 1970, with age of diagnosis shifting downwards. Both trends were likely impacted by administrative changes, while the latter is likely to be (partly) attributable to earlier detection and increased reporting of child‐onset conditions. Our findings may provide valuable context of the epidemiology of mental disorders across age groups for comparison with other studies and populations. [ABSTRACT FROM AUTHOR]

Importance: Premature mortality has been observed among people with mental disorders. Comorbid general medical conditions contribute substantially to this reduction in life expectancy.Objective: To provide an analysis of mortality associated with comorbidity between a broad range of mental disorders and general medical conditions.Design, Setting, and Participants: Population-based cohort study of 5 946 800 individuals born in Denmark from 1900 to 2015 and residing in the country at the start of follow-up (January 1, 2000, or their date of birth, whichever occurred later).Exposures: Danish health registers were used to identify people with mental disorders and general medical conditions.Main Outcomes and Measures: Considering pairs of mental disorders and general medical conditions, we calculated mortality rate ratios (MRRs) and differences in life expectancy (ie, life-years lost) to assess the association of mortality with both disorders of interest compared with the mental disorder of interest, the general medical condition of interest, and neither disorder of interest.Results: The study population comprised 2 961 397 males and 2 985 403 females, with a median (IQR) age of 32.0 years (7.3-52.9) at start of follow-up and 48.9 years (42.5-68.8) at the end. Based on all pairs of comorbid mental disorders and general medical conditions, the mean MRR compared with people without these conditions was 5.90 (median, 4.94; IQR, 3.80-7.30), and the mean reduction of life expectancy compared with the general population was 11.35 years (median, 11.08; range, 5.27-23.53; IQR, 8.22-13.72). The association with general medical condition comorbidity in those with mental disorders varied by general medical condition; for example, the addition of a neurological condition for each of the mental disorders was associated with a mean MRR of 1.22, whereas for cancer, the mean MRR for all mental disorders was 4.07.Conclusions and Relevance: In this study, shorter life expectancy was associated with comorbid mental disorders and general medical conditions compared with the entire population and also when compared with patients who had either mental disorders only or general medical conditions only. Prevention and early detection of comorbidities could reduce premature mortality in patients with mental disorders. [ABSTRACT FROM AUTHOR]

Importance: About 20% to 30% of people with schizophrenia have psychotic symptoms that do not respond adequately to first-line antipsychotic treatment. This clinical presentation, chronic and highly disabling, is known as treatment-resistant schizophrenia (TRS). The causes of treatment resistance and their relationships with causes underlying schizophrenia are largely unknown. Adequately powered genetic studies of TRS are scarce because of the difficulty in collecting data from well-characterized TRS cohorts.Objective: To examine the genetic architecture of TRS through the reassessment of genetic data from schizophrenia studies and its validation in carefully ascertained clinical samples.Design, Setting, and Participants: Two case-control genome-wide association studies (GWASs) of schizophrenia were performed in which the case samples were defined as individuals with TRS (n = 10 501) and individuals with non-TRS (n = 20 325). The differences in effect sizes for allelic associations were then determined between both studies, the reasoning being such differences reflect treatment resistance instead of schizophrenia. Genotype data were retrieved from the CLOZUK and Psychiatric Genomics Consortium (PGC) schizophrenia studies. The output was validated using polygenic risk score (PRS) profiling of 2 independent schizophrenia cohorts with TRS and non-TRS: a prevalence sample with 817 individuals (Cardiff Cognition in Schizophrenia [CardiffCOGS]) and an incidence sample with 563 individuals (Genetics Workstream of the Schizophrenia Treatment Resistance and Therapeutic Advances [STRATA-G]).Main Outcomes and Measures: GWAS of treatment resistance in schizophrenia. The results of the GWAS were compared with complex polygenic traits through a genetic correlation approach and were used for PRS analysis on the independent validation cohorts using the same TRS definition.Results: The study included a total of 85 490 participants (48 635 [56.9%] male) in its GWAS stage and 1380 participants (859 [62.2%] male) in its PRS validation stage. Treatment resistance in schizophrenia emerged as a polygenic trait with detectable heritability (1% to 4%), and several traits related to intelligence and cognition were found to be genetically correlated with it (genetic correlation, 0.41-0.69). PRS analysis in the CardiffCOGS prevalence sample showed a positive association between TRS and a history of taking clozapine (r2 = 2.03%; P = .001), which was replicated in the STRATA-G incidence sample (r2 = 1.09%; P = .04).Conclusions and Relevance: In this GWAS, common genetic variants were differentially associated with TRS, and these associations may have been obscured through the amalgamation of large GWAS samples in previous studies of broadly defined schizophrenia. Findings of this study suggest the validity of meta-analytic approaches for studies on patient outcomes, including treatment resistance. [ABSTRACT FROM AUTHOR]

Importance: Although the association between several recurrent genomic copy number variants (CNVs) and mental disorders has been studied for more than a decade, unbiased, population-based estimates of the prevalence, disease risks and trajectories, fertility, and mortality to contrast chromosomal abnormalities and advance precision health care are lacking.Objective: To generate unbiased, population-based estimates of prevalence, disease risks and trajectories, fertility, and mortality of CNVs implicated in neuropsychiatric disorders.Design, Setting, and Participants: In a population-based case-cohort study, using the Lundbeck Foundation Initiative for Integrative Psychiatric Research (iPSYCH) 2012 database, individuals born between May 1, 1981, and December 31, 2005, and followed up until December 31, 2012, were analyzed. All individuals (n = 57 377) with attention-deficit/hyperactivity disorder (ADHD), major depressive disorder (MDD), schizophrenia (SCZ), autism spectrum disorder (ASD), or bipolar disorder (BPD) were included, as well as 30 000 individuals randomly drawn from the database. Data analysis was conducted from July 1, 2017, to September 7, 2021.Exposures: Copy number variants at 6 genomic loci (1q21.1, 15q11.2, 15q13.3, 16p11.2, 17p12, and 17q12).Main Outcomes and Measures: Population-unbiased hazard ratio (HR) and survival estimates of CNV associations with the 5 ascertained psychiatric disorders, epilepsy, intellectual disability, selected somatic disorders, fertility, and mortality.Results: Participants' age ranged from 1 to 32 years (mean, 12.0 [IQR, 6.9] years) during follow-up, and 38 662 were male (52.3%). Copy number variants broadly associated with an increased risk of autism spectrum disorder and ADHD, whereas risk estimates of SCZ for most CNVs were lower than previously reported. Comparison with previous studies suggests that the lower risk estimates are associated with a higher CNV prevalence in the general population than in control samples of most case-control studies. Significant risk of major depressive disorder (HR, 5.8; 95% CI, 1.5-22.2) and sex-specific risk of bipolar disorder (HR, 17; 95% CI, 1.5-189.3, in men only) were noted for the 1q21.1 deletion. Although CNVs at 1q21.1 and 15q13.3 were associated with increased risk across most diagnoses, the 17p12 deletion consistently conferred less risk of psychiatric disorders (HR 0.4-0.8), although none of the estimates differed significantly from the general population. Trajectory analyses noted that, although diagnostic risk profiles differed across loci, they were similar for deletions and duplications within each locus. Sex-stratified analyses suggest that pathogenicity of many CNVs may be modulated by sex.Conclusions and Relevance: The findings of this study suggest that the iPSYCH population case cohort reveals broad disease risk for some of the studied CNVs and narrower risk for others, in addition to sex differential liability. This finding on genomic risk variants at the level of a population may be important for health care planning and clinical decision making, and thus the advancement of precision health care. [ABSTRACT FROM AUTHOR]

Objective: To investigate vagotomy, the severance of the vagus nerve, and its association with mental disorders, as gut‐brain communication partly mediated by the vagus nerve have been suggested as a risk factor. Methods: Nationwide population‐based Danish register study of all individuals alive and living in Denmark during the study period 1977–2016 and who had a hospital contact for ulcer with or without vagotomy. Follow‐up was until any diagnosis of mental disorders requiring hospital contact, emigration, death, or end of follow‐up on December 31, 2016, whichever came first. Data were analyzed using survival analysis and adjusted for sex, age, calendar year, ulcer type, and Charlson comorbidity index score. Results: During the study period, 113,086 individuals had a hospital contact for ulcer. Of these, 5,408 were exposed to vagotomy where 375 (6.9%) subsequently developed a mental disorder. Vagotomy overall was not associated with mental disorders (HR: 1.10; 95%CI: 0.99–1.23), compared to individuals with ulcer not exposed to vagotomy. However, truncal vagotomy was associated with an increased HR of 1.22 (95%CI: 1.06–1.41) for mental disorders, whereas highly selective vagotomy was not associated with mental disorders (HR: 0.98; 95%CI: 0.84–1.15). Truncal vagotomy was also associated with higher risk of mental disorders when compared to highly selective vagotomy (p = 0.034). Conclusions: Overall, vagotomy did not increase the risk of mental disorders; however, truncal vagotomy specifically was associated with a small risk increase in mental disorders, whereas no association was found for highly selective vagotomy. Thus, the vagus nerve does not seem to have a major impact on the development of mental disorders. [ABSTRACT FROM AUTHOR]

Introduction: An association between schizophrenia and urbanicity has long been observed, with studies in many countries, including several from Denmark, reporting that individuals born/raised in densely populated urban settings have an increased risk of developing schizophrenia compared to those born/raised in rural settings. However, these findings have not been replicated in all studies. In particular, a Western Australian study showed a gradient in the opposite direction which disappeared after adjustment for covariates. Given the different findings for Denmark and Western Australia, our aim was to investigate the relationship between schizophrenia and urbanicity in these two regions to determine which factors may be influencing the relationship. Methods: We used population-based cohorts of children born alive between 1980 and 2001 in Western Australia (N = 428,784) and Denmark (N = 1,357,874). Children were categorised according to the level of urbanicity of their mother's residence at time of birth and followed-up through to 30 June 2015. Linkage to State-based registers provided information on schizophrenia diagnosis and a range of covariates. Rates of being diagnosed with schizophrenia for each category of urbanicity were estimated using Cox proportional hazards models adjusted for covariates. Results: During follow-up, 1618 (0.4%) children in Western Australia and 11,875 (0.9%) children in Denmark were diagnosed with schizophrenia. In Western Australia, those born in the most remote areas did not experience lower rates of schizophrenia than those born in the most urban areas (hazard ratio = 1.02 [95% confidence interval: 0.81, 1.29]), unlike their Danish counterparts (hazard ratio = 0.62 [95% confidence interval: 0.58, 0.66]). However, when the Western Australian cohort was restricted to children of non-Aboriginal Indigenous status, results were consistent with Danish findings (hazard ratio = 0.46 [95% confidence interval: 0.29, 0.72]). Discussion: Our study highlights the potential for disadvantaged subgroups to mask the contribution of urban-related risk factors to risk of schizophrenia and the importance of stratified analysis in such cases. [ABSTRACT FROM AUTHOR]

Among patients with obsessive-compulsive disorder (OCD), 65–85% manifest another psychiatric disorder concomitantly or at some other time point during their life. OCD is highly heritable, as are many of its comorbidities. A possible genetic heterogeneity of OCD in relation to its comorbid conditions, however, has not yet been exhaustively explored. We used a framework of different approaches to study the genetic relationship of OCD with three commonly observed comorbidities, namely major depressive disorder (MDD), attention-deficit hyperactivity disorder (ADHD), and autism spectrum disorder (ASD). First, using publicly available summary statistics from large-scale genome-wide association studies, we compared genetic correlation patterns for OCD, MDD, ADHD, and ASD with 861 somatic and mental health phenotypes. Secondly, we examined how polygenic risk scores (PRS) of eight traits that showed heterogeneous correlation patterns with OCD, MDD, ADHD, and ASD partitioned across comorbid subgroups in OCD using independent unpublished data from the Lundbeck Foundation Initiative for Integrative Psychiatric Research (iPSYCH). The comorbid subgroups comprised of patients with only OCD (N = 366), OCD and MDD (N = 1,052), OCD and ADHD (N = 443), OCD and ASD (N = 388), and OCD with more than 1 comorbidity (N = 429). We found that PRS of all traits but BMI were significantly associated with OCD across all subgroups (neuroticism: p = 1.19 × 10−32, bipolar disorder: p = 7.51 × 10−8, anorexia nervosa: p = 3.52 × 10−20, age at first birth: p = 9.38 × 10−5, educational attainment: p = 1.56 × 10−4, OCD: p = 1.87 × 10−6, insomnia: p = 2.61 × 10−5, BMI: p = 0.15). For age at first birth, educational attainment, and insomnia PRS estimates significantly differed across comorbid subgroups (p = 2.29 × 10−4, p = 1.63 × 10−4, and p = 0.045, respectively). Especially for anorexia nervosa, age at first birth, educational attainment, insomnia, and neuroticism the correlation patterns that emerged from genetic correlation analysis of OCD, MDD, ADHD, and ASD were mirrored in the PRS associations with the respective comorbid OCD groups. Dissecting the polygenic architecture, we found both quantitative and qualitative polygenic heterogeneity across OCD comorbid subgroups. [ABSTRACT FROM AUTHOR]

This cohort study examines the association of polygenic risk score for major depression with risk of recurrence in individuals diagnosed with unipolar depression in hospital-based settings and estimates the absolute risk of recurrence based on polygenic risk. [ABSTRACT FROM AUTHOR]

Asthma with severe exacerbation is the most common cause of hospitalization among young children. We aim to increase the understanding of this clinically important disease entity through a genome-wide association study. The discovery analysis comprises 2866 children experiencing severe asthma exacerbation between ages 2 and 6 years, and 65,415 non-asthmatic controls, and we replicate findings in 918 children from the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC) birth cohorts. We identify rs281379 near FUT2/MAMSTR on chromosome 19 as a novel risk locus (OR = 1.18 (95% CI = 1.11–1.25), Pdiscovery = 2.6 × 10−9) as well as a biologically plausible interaction between functional variants in FUT2 and ABO. We further discover and replicate a potential causal mechanism behind this interaction related to S. pneumoniae respiratory illnesses. These results suggest a novel mechanism of early childhood asthma and demonstrates the importance of phenotype-specificity for discovery of asthma genes and epistasis. Genetic variants discovered through genome-wide association studies for asthma together account for a small portion of the heritability. Here, the authors identify a possible epistatic relationship between coding variants in FUT2 and ABO, especially pronounced in severe and early onset asthma. [ABSTRACT FROM AUTHOR]

Background: Links between parental socioeconomic position during childhood and subsequent risks of developing mental disorders have rarely been examined across the diagnostic spectrum. We conducted a comprehensive analysis of parental income level, including income mobility, during childhood and risks for developing mental disorders diagnosed in secondary care in young adulthood.Methods: National cohort study of persons born in Denmark 1980-2000 (N = 1,051,265). Parental income was measured during birth year and at ages 5, 10 and 15. Follow-up began from 15th birthday until mental disorder diagnosis or 31 December 2016, whichever occurred first. Hazard ratios and cumulative incidence were estimated.Results: A quarter (25.2%; 95% CI 24.8-25.6%) of children born in the lowest income quintile families will have a secondary care-diagnosed mental disorder by age 37, versus 13.5% (13.2-13.9%) of those born in the highest income quintile. Longer time spent living in low-income families was associated with higher risks of developing mental disorders. Associations were strongest for substance misuse and personality disorders and weaker for mood disorders and anxiety/somatoform disorders. An exception was eating disorders, with low parental income being associated with attenuated risk. For all diagnostic categories examined except for eating disorders, downward socioeconomic mobility was linked with higher subsequent risk and upward socioeconomic mobility with lower subsequent risk of developing mental disorders.Conclusions: Except for eating disorders, low parental income during childhood is associated with subsequent increased risk of mental disorders diagnosed in secondary care across the diagnostic spectrum. Early interventions to mitigate the disadvantages linked with low income, and better opportunities for upward socioeconomic mobility could reduce social and mental health inequalities. [ABSTRACT FROM AUTHOR]

Objective: The authors investigated the associations between polygenic liability and progression to bipolar disorder or psychotic disorders among individuals diagnosed with unipolar depression in early life.Methods: A cohort comprising 16,949 individuals (69% female, 10-35 years old at the first depression diagnosis) from the iPSYCH Danish case-cohort study (iPSYCH2012) who were diagnosed with depression in Danish psychiatric hospitals from 1994 to 2016 was examined. Polygenic risk scores (PRSs) for major depression, bipolar disorder, and schizophrenia were generated using the most recent results from the Psychiatric Genomics Consortium. Hazard ratios for each disorder-specific PRS were estimated using Cox regressions with adjustment for the other two PRSs. Absolute risk of progression was estimated using the cumulative hazard.Results: Patients were followed for up to 21 years (median=7 years, interquartile range, 5-10 years). The absolute risks of progression to bipolar disorder and psychotic disorders were 7.3% and 13.8%, respectively. After mutual adjustment for the other PRSs, only the PRS for bipolar disorder predicted progression to bipolar disorder (adjusted hazard ratio for a one-standard-deviation increase in PRS=1.11, 95% CI=1.03, 1.21), and only the PRS for schizophrenia predicted progression to psychotic disorders (adjusted hazard ratio=1.10, 95% CI=1.04, 1.16). After adjusting for PRSs, parental history still strongly predicted progression to bipolar disorder (adjusted hazard ratio=5.02, 95% CI=3.53, 7.14) and psychotic disorders (adjusted hazard ratio=1.63, 95% CI=1.30, 2.06).Conclusions: PRSs for bipolar disorder and schizophrenia are associated with risk for progression to bipolar disorder or psychotic disorders, respectively, among individuals diagnosed with depression; however, the effects are small compared with parental history, particularly for bipolar disorder. [ABSTRACT FROM AUTHOR]

Background: Residential mobility during upbringing, and especially adolescence, is associated with multiple negative mental health outcomes. However, whether associations are confounded by unmeasured familial factors, including genetic liability, is unclear.Aims: We used a population-based case-cohort study to assess whether polygenic risk scores (PRSs) for schizophrenia, bipolar disorder and major depression were associated with mobility from ages 10-14 years, and whether PRS and parental history of mental disorder together explained associations between mobility and each disorder.Method: Information on cases (n = 4207 schizophrenia, n = 1402 bipolar disorder, n = 18 215 major depression) and a random population sample (n = 17 582), born 1981-1997, was linked between Danish civil and psychiatric registries. Genome-wide data were obtained from the Danish Neonatal Screening Biobank and PRSs were calculated based on results of separate, large meta-analyses.Results: PRSs for schizophrenia and major depression were weakly associated with moving once (odds ratio 1.07, 95% CI 1.00-1.16; and odds ratio 1.10, 95% CI 1.04-1.17, respectively), but not twice or three or more times. Mobility was positively associated with each disorder, with more moves associated with greater risk. Adjustment for PRS produced slight reductions in the magnitude of associations. Adjustment for PRS and parental history of mental disorder together reduced estimates by 5-11%. In fully adjusted models mobility was associated with all three disorders; hazard ratios ranged from 1.33 (95% CI 1.08-1.62; one move and bipolar disorder) to 3.05 (95% CI 1.92-4.86; three or more moves and bipolar disorder).Conclusions: Associations of mobility with schizophrenia, bipolar disorder and depression do not appear to be attributable to genetic liability as measured here. Potential familial confounding of mobility associations may be predominantly environmental in nature. [ABSTRACT FROM AUTHOR]

Importance: Anxiety and stress-related disorders are among the most common mental disorders. Although family and twin studies indicate that both genetic and environmental factors play an important role underlying their etiology, the genetic underpinnings of anxiety and stress-related disorders are poorly understood.Objectives: To estimate the single-nucleotide polymorphism-based heritability of anxiety and stress-related disorders; to identify novel genetic risk variants, genes, or biological pathways; to test for pleiotropic associations with other psychiatric traits; and to evaluate the association of psychiatric comorbidities with genetic findings.Design, Setting, Participants: This genome-wide association study included individuals with various anxiety and stress-related diagnoses and controls derived from the population-based Lundbeck Foundation Initiative for Integrative Psychiatric Research (iPSYCH) study. Lifetime diagnoses of anxiety and stress-related disorders were obtained through the national Danish registers. Genes of interest were further evaluated in mice exposed to chronic social defeat. The study was conducted between June 2016 and November 2018.Main Outcomes and Measures: Diagnoses of a relatively broad diagnostic spectrum of anxiety and stress-related disorders.Results: The study sample included 12 655 individuals with various anxiety and stress-related diagnoses and 19 225 controls. Overall, 17 740 study participants (55.6%) were women. A total of 7308 participants (22.9%) were born between 1981-1985, 8840 (27.7%) between 1986-1990, 8157 (25.6%) between 1991-1995, 5918 (18.6%) between 1996-2000, and 1657 (5.2%) between 2001-2005. Standard association analysis revealed variants in PDE4B to be associated with anxiety and stress-related disorder (rs7528604; P = 5.39 × 10-11; odds ratio = 0.89; 95% CI, 0.86-0.92). A framework of sensitivity analyses adjusting for mental comorbidity supported this result showing consistent association of PDE4B variants with anxiety and stress-related disorder across analytical scenarios. In mouse models, alterations in Pde4b expression were observed in those mice displaying anxiety-like behavior after exposure to chronic stress in the prefrontal cortex (P = .002; t = -3.33) and the hippocampus (P = .001; t = -3.72). We also found a single-nucleotide polymorphism heritability of 28% (standard error = 0.027) and that the genetic signature of anxiety and stress-related overlapped with psychiatric traits, educational outcomes, obesity-related phenotypes, smoking, and reproductive success.Conclusions and Relevance: This study highlights anxiety and stress-related disorders as complex heritable phenotypes with intriguing genetic correlations not only with psychiatric traits, but also with educational outcomes and multiple obesity-related phenotypes. Furthermore, we highlight the candidate gene PDE4B as a robust risk locus pointing to the potential of PDE4B inhibitors in treatment of these disorders. [ABSTRACT FROM AUTHOR]

Importance: Although the usefulness of polygenic risk scores as a measure of genetic liability for major depression (MD) has been established, their association with depression in the general population remains relatively unexplored.Objective: To evaluate whether polygenic risk scores for MD, bipolar disorder (BD), and schizophrenia (SZ) are associated with depression in the general population and explore whether these polygenic liabilities are associated with heterogeneity in terms of age at onset and severity at the initial depression diagnosis.Design, Setting, and Participants: Participants were drawn from the Danish iPSYCH2012 case-cohort study, a representative sample drawn from the population of Denmark born between May 1, 1981, and December 31, 2005. The hazard of depression was estimated using Cox regressions modified to accommodate the case-cohort design. Case-only analyses were conducted using linear and multinomial regressions. The data analysis was conducted from February 2017 to June 2018.Exposures: Polygenic risk scores for MD, BD, and SZ trained using the most recent genome-wide association study results from the Psychiatric Genomics Consortium.Main Outcomes and Measures: The main outcome was first depressive episode (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision [ICD-10] code F32) treated in hospital-based psychiatric care. Severity at the initial diagnosis was measured using the ICD-10 code severity specifications (mild, moderate, severe without psychosis, and severe with psychosis) and treatment setting (inpatient, outpatient, and emergency).Results: Of 34 573 participants aged 10 to 31 years at censoring, 68% of those with depression were female compared with 48.9% of participants without depression. Each SD increase in polygenic liability for MD, BD, and SZ was associated with 30% (hazard ratio [HR], 1.30; 95% CI, 1.27-1.33), 5% (HR, 1.05; 95% CI, 1.02-1.07), and 12% (HR, 1.12; 95% CI, 1.09-1.15) increases in the hazard of depression, respectively. Among cases, a higher polygenic liability for BD was associated with earlier depression onset (β = -.07; SE = .02; P = .002).Conclusions and Relevance: Polygenic liability for MD is associated with first depression in the general population, which supports the idea that these scores tap into an underlying liability for developing the disorder. The fact that polygenic risk for BD and polygenic risk for SZ also were associated with depression is consistent with prior evidence that these disorders share some common genetic overlap. Variations in polygenic liability may contribute slightly to heterogeneity in clinical presentation, but these associations appear minimal. [ABSTRACT FROM AUTHOR]

Importance: Infections have been associated with increased risks for mental disorders, such as schizophrenia and depression. However, the association between all infections requiring treatment and the wide range of mental disorders is unknown to date.Objective: To investigate the association between all treated infections since birth and the subsequent risk of development of any treated mental disorder during childhood and adolescence.Design, Setting, and Participants: Population-based cohort study using Danish nationwide registers. Participants were all individuals born in Denmark between January 1, 1995, and June 30, 2012 (N = 1 098 930). Dates of analysis were November 2017 to February 2018.Exposures: All treated infections were identified in a time-varying manner from birth until June 30, 2013, including severe infections requiring hospitalizations and less severe infection treated with anti-infective agents in the primary care sector.Main Outcomes and Measures: This study identified all mental disorders diagnosed in a hospital setting and any redeemed prescription for psychotropic medication. Cox proportional hazards regression was performed reporting hazard rate ratios (HRRs), including 95% CIs, adjusted for age, sex, somatic comorbidity, parental education, and parental mental disorders.Results: A total of 1 098 930 individuals (51.3% male) were followed up for 9 620 807.7 person-years until a mean (SD) age of 9.76 (4.91) years. Infections requiring hospitalizations were associated with subsequent increased risk of having a diagnosis of any mental disorder (n = 42 462) by an HRR of 1.84 (95% CI, 1.69-1.99) and with increased risk of redeeming a prescription for psychotropic medication (n = 56 847) by an HRR of 1.42 (95% CI, 1.37-1.46). Infection treated with anti-infective agents was associated with increased risk of having a diagnosis of any mental disorder (HRR, 1.40; 95% CI, 1.29-1.51) and with increased risk of redeeming a prescription for psychotropic medication (HRR, 1.22; 95% CI, 1.18-1.26). Antibiotic use was associated with particularly increased risk estimates. The risk of mental disorders after infections increased in a dose-response association and with the temporal proximity of the last infection. In particular, schizophrenia spectrum disorders, obsessive-compulsive disorder, personality and behavior disorders, mental retardation, autistic spectrum disorder, attention-deficit/hyperactivity disorder, oppositional defiant disorder and conduct disorder, and tic disorders were associated with the highest risks after infections.Conclusions and Relevance: Although the results cannot prove causality, these findings provide evidence for the involvement of infections and the immune system in the etiology of a wide range of mental disorders in children and adolescents. [ABSTRACT FROM AUTHOR]

Mitochondrial DNA (mtDNA) haplogroups (hgs) are evolutionarily conserved sets of mtDNA SNP-haplotypes with characteristic geographical distribution. Associations of hgs with disease and physiological characteristics have been reported, but have frequently not been reproducible. Using 418 mtDNA SNPs on the PsychChip (Illumina), we assessed the spatio-temporal distribution of mtDNA hgs in Denmark from DNA isolated from 24,642 geographically un-biased dried blood spots (DBS), collected from 1981 to 2005 through the Danish National Neonatal Screening program. ADMIXTURE was used to establish the genomic ancestry of all samples using a reference of 100K+ autosomal SNPs in 2,248 individuals from nine populations. Median-joining analysis determined that the hgs were highly variable, despite being typically Northern European in origin, suggesting multiple founder events. Furthermore, considerable heterogeneity and variation in nuclear genomic ancestry was observed. Thus, individuals with hg H exhibited 95%, and U hgs 38.2% - 92.5%, Danish ancestry. Significant clines between geographical regions and rural and metropolitan populations were found. Over 25 years, macro-hg L increased from 0.2% to 1.2% (p = 1.1*E-10), and M from 1% to 2.4% (p = 3.7*E-8). Hg U increased among the R macro-hg from 14.1% to 16.5% (p = 1.9*E-3). Genomic ancestry, geographical skewedness, and sub-hg distribution suggested that the L, M and U increases are due to immigration. The complex spatio-temporal dynamics and genomic ancestry of mtDNA in the Danish population reflect repeated migratory events and, in later years, net immigration. Such complexity may explain the often contradictory and population-specific reports of mito-genomic association with disease. [ABSTRACT FROM AUTHOR]

Mitochondria play a significant role in human diseases. However, disease associations with mitochondrial DNA (mtDNA) SNPs have proven difficult to replicate. An analysis of eight schizophrenia-associated mtDNA SNPs, in 23,743 Danes without a psychiatric diagnosis and 2,538 schizophrenia patients, revealed marked inter-allelic differences in mitochondrial haplogroup affiliation and nuclear ancestry. This bi-genomic dependence could entail population stratification. Only two mitochondrial SNPs, m.15043A and m.15218G, were significantly associated with schizophrenia. However, these associations disappeared when corrected for haplogroup affiliation and nuclear ancestry. The extensive bi-genomic dependence documented here is a major concern when interpreting historic, as well as designing future, mtDNA association studies. [ABSTRACT FROM AUTHOR]

Otitis media infections and antibiotic treatment have been linked to the risk of developing autism spectrum disorder. Broad‐spectrum antibiotics may alter the composition of the gut flora microbiota, which is hypothesized to be involved in the regulation of the immune system. This study examines the interplay among otitis media, antibiotics, and the subsequent risk of developing autism. Based on the entire Danish population, 780,547 children were followed from birth (January 1, 1997 to December 31, 2008) until December 31, 2012. We calculated adjusted hazard ratios and absolute risks of autism with 95% confidence intervals (CIs) related to previous otitis media diagnoses and antibiotic prescriptions redeemed at Danish pharmacies. The absolute risk of autism before age 10 was increased among children with otitis media (1.2% for females and 3.3% for males) and in children who had redeemed an antibiotic prescription (0.6% and 2.7% for females and males) compared to children without a history of otitis media and antibiotics usage (0.4% for females and 1.9% for males). Similarly, we found an increased hazard ratio of autism associated with otitis media (1.83 95% CI 1.71–1.95) and antibiotics usage (1.29 95% CI 1.17–1.43). A history of both otitis media and antibiotic treatment did not further increase the risk of autism. Although the risk of autism was associated with otitis media and treatment with antibiotics, we found little evidence of a synergistic effect between otitis media infections and treatment with antibiotics. Autism Res2018, 11: 1432–1440. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. Lay Summary: We investigated whether otitis media ear infections and antibiotic treatment were associated with autism spectrum disorder. Autism was more common in children who had had an otitis media infection or who had been treated with antibiotics. Given the observational nature of our data, our study cannot be used to conclude that otitis media or use of antibiotics cause autism, as our findings may be subject to unobserved confounding. [ABSTRACT FROM AUTHOR]

Background: Attention-deficit hyperactivity disorder (ADHD) and anxiety disorders have been proposed as precursors of bipolar disorder, but their joint and relative roles in the development of bipolar disorder are unknown.AimsTo test the prospective relationship of ADHD and anxiety with onset of bipolar disorder.Method: We examined the relationship between ADHD, anxiety disorders and bipolar disorder in a birth cohort of 2 409 236 individuals born in Denmark between 1955 and 1991. Individuals were followed from their sixteenth birthday or from January 1995 to their first clinical contact for bipolar disorder or until December 2012. We calculated incidence rates per 10 000 person-years and tested the effects of prior diagnoses on the risk of bipolar disorder in survival models.Results: Over 37 394 865 person-years follow-up, 9250 onsets of bipolar disorder occurred. The incidence rate of bipolar disorder was 2.17 (95% CI 2.12-2.19) in individuals with no prior diagnosis of ADHD or anxiety, 23.86 (95% CI 19.98-27.75) in individuals with a prior diagnosis of ADHD only, 26.05 (95% CI 24.47-27.62) in individuals with a prior diagnosis of anxiety only and 66.16 (95% CI 44.83-87.47) in those with prior diagnoses of both ADHD and anxiety. The combination of ADHD and anxiety increased the risk of bipolar disorder 30-fold (95% CI 21.66-41.40) compared with those with no prior ADHD or anxiety.Conclusions: Early manifestations of both internalising and externalising psychopathology indicate liability to bipolar disorder. The combination of ADHD and anxiety is associated with a very high risk of bipolar disorder.Declaration of interestNone. [ABSTRACT FROM AUTHOR]

Importance: People with mental illness are more likely to have contact with the criminal justice system, but research to date has focused on risk of offense perpetration, while less is known about risk of being subjected to crime and violence.Objectives: To establish the incidence of being subjected to all types of criminal offenses, and by violent crimes separately, after onset of mental illness across the full diagnostic spectrum compared with those in the population without mental illness.Design, Setting, and Participants: This investigation was a longitudinal national cohort study using register data in Denmark. Participants were a cohort of more than 2 million persons born between 1965 and 1998 and followed up from 2001 or from their 15th birthday until December 31, 2013. Analysis was undertaken from November 2016 until February 2018.Exposures: Cohort members were followed up for onset of mental illness, recorded as first contact with outpatient or inpatient mental health services. Diagnoses across the full spectrum of psychiatric diagnoses were considered separately for men and women.Main Outcomes and Measures: Incidence rate ratios (IRRs) were estimated for first subjection to crime event (any crime and violent crime) reported to police after onset of mental illness. The IRRs were adjusted for cohort member's own criminal offending, in addition to several sociodemographic factors.Results: In a total cohort of 2 058 063 (48.7% male; 51.3% female), the adjusted IRRs for being subjected to crime associated with any mental disorder were 1.49 (95% CI, 1.46-1.51) for men and 1.64 (95% CI, 1.61-1.66) for women. The IRRs were higher for being subjected to violent crime at 1.76 (95% CI, 1.72-1.80) for men and 2.72 (95% CI, 2.65-2.79) for women. The strongest associations were for persons diagnosed as having substance use disorders and personality disorders, but significant risk elevations were found across almost all diagnostic groups examined.Conclusions and Relevance: Onset of mental illness is associated with increased risk of exposure to crime, and violent crime in particular. Elevated risk is not confined to specific diagnostic groups. Women with mental illness are especially vulnerable to being subjected to crime. Individual's own offending accounts for some but not all of the increased vulnerability to being subjected to crime. [ABSTRACT FROM AUTHOR]

Background: Few studies have investigated mortality risk in individuals with tic disorders.Methods: We thus measured the risk of premature death in individuals with tic disorders and with Tourette syndrome in a prospective cohort study with 80 million person-years of follow-up. We estimated mortality rate ratios and adjusted for calendar year, age, sex, urbanicity, maternal and paternal age, and psychiatric disorders to compare individuals with and without tic disorders.Results: The risk of premature death was higher among individuals with tic disorders (mortality rate ratio, 2.02; 95% CI, 1.49-2.66) and with Tourette syndrome (mortality rate ratio, 1.63; 95% CI, 1.11-2.28) compared with controls. After the exclusion of individuals with comorbid attention-deficit/hyperactivity disorder, obsessive-compulsive disorder, and substance abuse, tic disorder remained associated with increased mortality risk (mortality rate ratio, 2.30; 95% CI, 1.57-3.23), as did also Tourette Syndrome (mortality rate ratio, 1.81; 95% CI, 1.11-2.75).Conclusions: These results are of clinical significance for clinicians and advocacy organizations. Several factors may contribute to this increased risk of premature death, and more research mapping out these factors is needed. © 2017 International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]

Importance: Microdeletions and duplications have been described at the 22q11.2 locus. However, little is known about the clinical and epidemiologic consequences at the population level.Objective: To identify indicators of deletions or duplications at the 22q11.2 locus and estimate the incidence rate ratios (IRRs) and absolute risk for psychiatric disorders in clinically identified individuals with 22q11.2 deletion or duplication.Design, Setting, and Participants: A Danish nationwide register study including all individuals recorded in the Danish Cytogenetic Central Register with a 22q11.2 deletion or duplication was performed. A total of 3 768 943 individuals born in Denmark from 1955 to 2012 were followed up during the study period (total follow-up, 57.1 million person-years). Indicators of 22q11.2 deletion or duplication and cumulative incidences were estimated using a nested case-control design that included individuals from the population-based cohort. Survival analysis was used to compare risk of disease in individuals with and without the 22q11.2 deletion or duplication. The study was conducted from May 7, 2015, to August 14, 2016.Exposure: The 22q11.2 deletion or duplication.Main Outcomes and Measures: Indicators for carrying a 22q11.2 deletion or duplication, IRR, and cumulative incidences for psychiatric diagnoses (International Statistical Classification of Diseases and Related Health Problems, 10th Revision, codes F00-F99), including schizophrenia-spectrum disorders, mood disorders, neurotic stress-related and somatoform disorders, and a range of developmental and childhood disorders.Results: Among the 3 768 943 participants, 244 (124 [50.8%] male) and 58 (29 [50.0%] male) individuals were clinically identified with a 22q11.2 deletion or duplication, respectively. Mean (SD) age at diagnosis of any psychiatric disorder was 12.5 (8.3) years for individuals with deletions and 6.1 (0.9) years for duplication carriers. A parental diagnosis of schizophrenia-but not of other psychiatric diagnoses-was associated with a 22q11.2 deletion, and parental psychiatric diagnoses other than schizophrenia were associated with duplication carrier status. Both the 22q11.2 deletion (IRR, 4.24; 95% CI, 3.07-5.67) and duplication (IRR, 4.99; 95% CI, 1.79-10.72) was associated with increased risk of any psychiatric disorders. Furthermore, a highly increased risk of intellectual disability was found for the deletion (IRR, 34.08; 95% CI, 22.39-49.27) and duplication (IRR, 33.86; 95% CI, 8.42-87.87). Furthermore, individuals with the 22q11.2 deletion had an increased risk of several psychiatric disorders under study, for example, pervasive developmental disorders (IRR, 9.45; 95% CI, 5.64-14.69) and childhood autism (IRR, 8.94; 95% CI, 3.21-19.23).Conclusions and Relevance: Individuals with the 22q11.2 deletion or duplication have a significantly increased risk of developing psychiatric disorders. Survival analysis of persons carrying either the 22q11.2 deletion or duplication provides estimates of direct clinical relevance useful to assist clinical ascertainment, genetic counseling, guidance of symptomatic monitoring, and early clinical intervention. [ABSTRACT FROM AUTHOR]

Background: Anxiety disorders and depression are the most common mental disorders worldwide and have a striking impact on global disease burden. Although depression has consistently been found to increase mortality; the role of anxiety disorders in predicting mortality risk is unclear.Aims: To assess mortality risk in people with anxiety disorders.Method: We used nationwide Danish register data to conduct a prospective cohort study with over 30 million person-years of follow-up.Results: In total, 1066 (2.1%) people with anxiety disorders died during an average follow-up of 9.7 years. The risk of death by natural and unnatural causes was significantly higher among individuals with anxiety disorders (natural mortality rate ratio (MRR) = 1.39, 95% CI 1.28-1.51; unnatural MRR = 2.46, 95% CI 2.20-2.73) compared with the general population. Of those who died from unnatural causes, 16.5% had comorbid diagnoses of depression (MRR = 11.72, 95% CI 10.11-13.51).Conclusions: Anxiety disorders significantly increased mortality risk. Comorbidity of anxiety disorders and depression played an important part in the increased mortality. [ABSTRACT FROM AUTHOR]

Background: Attention-deficit/hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder with early onset. ADHD is associated with significant morbidity and mortality, partly due to delayed diagnosis. Identification of children at high risk for developing ADHD could lead to earlier diagnosis and potentially change the negative trajectory of the illness for the better. Since early psychosocial adversity is considered to be a likely etiological risk factor for ADHD, markers of this construct may be useful for early identification of children at high risk. Therefore, we sought to investigate whether Rutter’s indicators of adversity (low social class, severe marital discord, large family size, paternal criminality, maternal mental disorder, and placement in out-of-home care) assessed in infancy could serve as early predictors for the development of ADHD. Methods and Findings: Using data from the Danish nationwide population-based registers, we established a cohort consisting of all 994,407 children born in Denmark between January 1st 1993 and December 31st 2011 and extracted dichotomous values for the six Rutter’s indicators of adversity at age 0–12 months (infancy) for each cohort member. The cohort members were followed from their second birthday and the association between the sum of Rutter’s indicators of adversity (RIA-score) in infancy and subsequent development of ADHD was estimated by means of Cox regression. Also, the number needed to screen (NNS) to detect one case of ADHD based on the RIA-scores in infancy was calculated. During follow-up (9.6 million person-years), 15,857 males and 5,663 females from the cohort developed ADHD. For both males and females, there was a marked dose-response relationship between RIA-scores assessed in infancy and the risk for developing ADHD. The hazard ratios for ADHD were 11.0 (95%CI: 8.2–14.7) and 11.4 (95%CI: 7.1–18.3) respectively, for males and females with RIA-scores of 5–6, compared to males and females with RIA-scores of 0. Among males with RIA-scores of 5–6, 37.6% (95%CI: 27.0–50.7) had been diagnosed with ADHD prior to the age of 20, corresponding to a NNS of 3.0 (95%CI: 2.2–4.0). Conclusions: Rutter’s indicators of adversity assessed in infancy strongly predicted ADHD. This knowledge may be important for early identification of ADHD. [ABSTRACT FROM AUTHOR]

Objective: Cross-sectional studies have shown associations between 22q11.2 deletion syndrome and schizophrenia. However, large-scale prospective studies have been lacking. We, therefore, conducted the first large-scale population based study on the risk of being diagnosed with schizophrenia in persons identified with 22q11.2 deletion syndrome. Methods: Danish nationwide registers were linked to establish a cohort consisting of all Danish citizens born during 1955–2004 and the cohort was followed from January 1, 1994 until December 31, 2013. Data were analyzed using survival analyses and adjusted for calendar year, age, sex, and parental mental health history. Results: A total of 156 individuals with 22q11.2 deletion syndrome were identified, out of which 6 individuals were diagnosed with schizophrenia spectrum disorders following identification with 22q11 deletion syndrome. Identified carriers of 22q11.2 deletion had an 8.13(95% CI: 3.65–18.09) fold increased risk of schizophrenia spectrum disorder. Conclusions: Carriers of a 22q11.2 deletion who had been clinically identified had a highly increased risk of schizophrenia spectrum disorders. [ABSTRACT FROM AUTHOR]

Importance: Evidence suggests that long-term trajectories of major depressive disorder (MDD) are heterogeneous. The Danish Psychiatric Central Research Register (DPCRR) provides a rare opportunity to examine patterns and correlates of long-term trajectories in a large sample of patients with moderate to severe MDD.Objective: To characterize patterns and correlates of 10-year course trajectories of MDD in the DPCRR.Design, Setting, and Participants: A cohort containing 11 640 individuals born in Denmark in 1955 or later with their first recorded MDD diagnosis in the DPCRR between 1995 and 2002 was established. Patients were followed for 10 years from the date of their initial MDD diagnosis. Data were obtained from Danish civil and psychiatric national registers in June 2013 and were analyzed from April 4, 2014, to December 17, 2015. Correlates of trajectory class membership were sex, characteristics of the first recorded MDD episode (ie, age, severity, inpatient treatment, and record of suicide attempt or self-harm), and psychiatric diagnoses in parents (ie, depression, bipolar disorder, schizophrenia-spectrum disorders, substance abuse, and anxiety or somatoform disorders).Main Outcomes and Measures: The outcome variable was past-year contact at a psychiatric hospital with a main diagnosis of MDD during each of the 10 years following the initial MDD diagnosis. Trajectories were modeled using latent class growth analysis.Results: The sample included 11 640 individuals (7493 [64.4%] women) aged 18 to 48 years (mean [SD], 31.4 [7.3]) at their first recorded MDD diagnosis. Four trajectory classes were identified: brief contact (77.0%) (characterized by low probability of contact after 2 years); prolonged initial contact (12.8%) (characterized by high decreasing probability of contact during the first 5 years); later reentry (7.1%) (characterized by moderate probability of contact during the second 5 years); and persistent contact (3.1%) (characterized by high or moderate probability of contact throughout). Female sex (odds ratio [OR] range, 1.82-2.22), inpatient treatment (OR range, 1.40-1.50), and severity at first recorded MDD episode (OR range: moderate, 1.61-1.84; severe, 1.93-2.23; and psychotic, 2.73-3.07) were associated with more severe trajectories. Parental anxiety (OR, 1.34 [95% CI, 1.10-1.63]) and depression (OR, 1.63 [95% CI, 1.28-2.09]) were associated with the prolonged initial contact and later reentry classes, respectively. Parental schizophrenia was associated with the persistent contact class (OR range, 2.55-3.04).Conclusions and Relevance: Most people treated for moderate to severe MDD in Danish psychiatric hospitals do not receive additional MDD treatment after 2 years; however, a minority receive specialty treatment for up to a decade. Observable heterogeneity in the course may be indicative of underlying etiologic differences. [ABSTRACT FROM AUTHOR]

Importance: Several mental disorders have consistently been found to be associated with decreased life expectancy, but little is known about whether this is also the case for obsessive-compulsive disorder (OCD).Objective: To determine whether persons who receive a diagnosis of OCD are at increased risk of death.Design, Setting, and Participants: Using data from Danish registers, we conducted a nationwide prospective cohort study with 30 million person-years of follow-up. The data were collected from Danish longitudinal registers. A total of 3 million people born between 1955 and 2006 were followed up from January 1, 2002, through December 31, 2011. During this period, 27,236 people died. The data were analyzed primarily in June 2015.Main Outcomes and Measures: We estimated mortality rate ratios (MRRs), adjusted for calendar year, age, sex, maternal and paternal age, place of residence at birth, and somatic comorbidities, to compare persons with OCT with persons without OCD.Results: Of 10,155 persons with OCD (5935 women and 4220 men with a mean [SD] age of 29.1 [11.3] years who contributed a total of 54,937 person-years of observation), 110 (1.1%) died during the average follow-up of 9.7 years. The risk of death by natural or unnatural causes was significantly higher among persons with OCD (MRR, 1.68 [95% CI, 1.31-2.12] for natural causes; MRR, 2.61 [95% CI, 1.91-3.47] for unnatural causes) than among the general population. After the exclusion of persons with comorbid anxiety disorders, depression, or substance use disorders, OCD was still associated with increased mortality risk (MRR, 1.88 [95% CI, 1.27-2.67]).Conclusions and Relevance: The presence of OCD was associated with a significantly increased mortality risk. Comorbid anxiety disorders, depression, or substance use disorders further increased the risk. However, after adjusting for these and somatic comorbidities, we found that the mortality risk remained significantly increased among persons with OCD. [ABSTRACT FROM AUTHOR]

Background: Despite substantial similarities and overlaps in the pathophysiology of obsessive-compulsive disorders (OCD) and autism spectrum disorders, little is known about the clinical and etiologic cohesion of these two disorders. We therefore aimed to determine the patterns of comorbidity, longitudinal risks, and shared familial risks between these disorders. Methods: In a prospective study design we explored the effect of a prior diagnosis of OCD in patients and parents on the susceptibility to autism spectrum disorders and vice versa. Analyses were adjusted for sex, age, calendar year, parental age and place at residence at time of birth. As measures of relative risk incidence rate ratios (IRR) and accompanying 95% confidence intervals (CIs) were employed. Results: The risk of a comorbid diagnosis of OCD in individuals with autism spectrum disorder and aggregation of autism spectrum disorders in offspring of parents with OCD were increased. Individuals first diagnosed with autism spectrum disorders had a 2-fold higher risk of a later diagnosis of OCD (IRR = 2.18, 95% CI = 1.91–2.48), whereas individuals diagnosed with OCD displayed a nearly 4-fold higher risk to be diagnosed with autism spectrum disorders (IRR = 3.91, 95% CI = 3.46–4.40) later in life. The observed associations were somewhat stronger for less severe types of autism spectrum disorders without a comorbid diagnosis of mental disabilities. Conclusions: The high comorbidity, sequential risk, and shared familial risks between OCD and autism spectrum disorders are suggestive of partially shared etiological mechanisms. The results have implications for current gene-searching efforts and for clinical practice. [ABSTRACT FROM AUTHOR]

Anxiety disorders and anorexia nervosa are frequently acknowledged to be highly comorbid conditions, but still, little is known about the clinical and aetiological cohesion of specific anxiety diagnoses and anorexia nervosa. Using the comprehensive Danish population registers, we aimed to determine the risk of anorexia nervosa in patients with register-detected severe anxiety disorders. We also explored whether parental psychopathology was associated with offspring's anorexia nervosa. Anxiety disorders increased the risk of subsequent anorexia nervosa, with the highest risk observed in obsessive-compulsive disorder. Especially, male anxiety patients were at an increased risk for anorexia nervosa. Furthermore, an increased risk was observed in offspring of fathers with panic disorder. A diagnosis of an anxiety disorder, specifically obsessive-compulsive disorder, constitutes a risk factor for subsequent diagnosis of anorexia nervosa. These observations support the notion that anxiety disorders and anorexia nervosa share etiological mechanisms and/or that anxiety represents one developmental pathway to anorexia nervosa. Copyright © 2015 John Wiley & Sons, Ltd and Eating Disorders Association. [ABSTRACT FROM AUTHOR]

Background Clinical and population-based studies report increased prevalence of autism spectrum disorders (ASD) in individuals with anorexia nervosa and in their relatives. No nationwide study has yet been published on co-occurrence of these disorders. Aims To investigate comorbidity of ASD in individuals with anorexia nervosa, and aggregation of ASD and anorexia nervosa in their relatives. Method In Danish registers we identified all individuals born in 1981-2008, their parents, and full and half siblings, and linked them to data on hospital admissions for psychiatric disorders. Results Risk of comorbidity of ASD in probands with anorexia nervosa and aggregation of ASD in families of anorexia nervosa probands were increased. However, the risk of comorbid and familial ASD did not differ significantly from comorbid and familial major depression or any psychiatric disorder in anorexia nervosa probands. Conclusions We confirm aggregation of ASD in probands with anorexia nervosa and in their relatives; however, the relationship between anorexia nervosa and ASD appears to be non- specific. [ABSTRACT FROM AUTHOR]

Introduction: Childhood adversity is gaining increasing attention as a plausible etiological factor in the development of psychotic disorders. Childhood residential mobility is a potential risk factor that has received little attention in this context. Methods: We used registry data to estimate associations of residential mobility with narrow and broad schizophrenia and bipolar disorder across the course of childhood among 1.1 million individuals born in Denmark 1971–1991 and followed from age 15 through 2010. We assessed effect modification by sex, family history of mental disorder, the presence of siblings close in age, and distance moved. Results: In individual-year models adjusted for family history, urbanicity at birth, and parental age, mobility at all ages except the year of birth was associated with heightened risk of narrow and broad schizophrenia, and risk increased with age at moving and with the number of moves. Further adjustment for mobility at all ages 0–15 revealed associations mainly during the latter half of childhood, which were strongest during adolescence. Associations between mobility and bipolar disorder were fewer and weaker compared to schizophrenia. There was modest evidence of interaction with family history of psychiatric diagnosis, but little evidence for interaction by sex, the presence of closely-aged siblings, or distance moved. Schizophrenia associations did not appear attributable to increased mobility among adolescents with earlier onset. Conclusions: Mobility may increase risk for psychotic disorders, particularly schizophrenia. Children may be especially vulnerable during adolescence. Future research should investigate the importance of school changes and the potential for interaction with genetic risk. [ABSTRACT FROM PUBLISHER]

Objective: Schizophrenia is associated with excess physical comorbidity. Yet, to our knowledge, large studies are lacking on the associations with somatic diseases before the onset of schizophrenia. The authors conducted a nationwide study of the full spectrum of treated somatic diseases before the first diagnosis of schizophrenia. Method: Nationwide sample of the Danish population consisting of singletons (n = 954351) born 1977–1993 and followed from birth to 2009, during which period 4371 developed schizophrenia. Somatic diagnoses at all general hospital contacts (admitted or outpatient care at a somatic hospital) from 1977 to 2009 were used as exposures. The incidence rate ratio (IRR) of schizophrenia was calculated using Poisson regression adjusted for confounders. Results: Among the 4371 persons who developed schizophrenia from 1992 to 2009, a total of 4180 (95.6%) persons had a previous somatic hospital contact. A history of any somatic hospital contact was associated with an elevated risk of schizophrenia (IRR = 2.04, 95% CI = 1.77–2.37). A wide range of somatic diseases and conditions were associated with an increased risk of schizophrenia, including epilepsy (IRR = 2.26, 95% CI = 1.93–2.62), nutritional or metabolic disorders (IRR = 1.57, 95% CI = 1.39–1.77), circulatory system diseases (IRR = 1.63, 95% CI= 1.38–1.92), and brain injury (IRR = 1.58, 95% CI = 1.45–1.72). Conclusions: A wide range of potential etiological factors could have contributed to the observed associations, including genetic or physiological overlaps between conditions, and interacting immunological, behavioral, and neurodevelopmental factors. [ABSTRACT FROM PUBLISHER]