Accounting for age of onset and family history improves power in genome-wide association studies.

Genome-wide association studies (GWASs) have revolutionized human genetics, allowing researchers to identify thousands of disease-related genes and possible drug targets. However, case-control status does not account for the fact that not all controls may have lived through their period of risk for the disorder of interest. This can be quantified by examining the age-of-onset distribution and the age of the controls or the age of onset for cases. The age-of-onset distribution may also depend on information such as sex and birth year. In addition, family history is not routinely included in the assessment of control status. Here, we present LT-FH++, an extension of the liability threshold model conditioned on family history (LT-FH), which jointly accounts for age of onset and sex as well as family history. Using simulations, we show that, when family history and the age-of-onset distribution are available, the proposed approach yields statistically significant power gains over LT-FH and large power gains over genome-wide association study by proxy (GWAX). We applied our method to four psychiatric disorders available in the iPSYCH data and to mortality in the UK Biobank and found 20 genome-wide significant associations with LT-FH++, compared to ten for LT-FH and eight for a standard case-control GWAS. As more genetic data with linked electronic health records become available to researchers, we expect methods that account for additional health information, such as LT-FH++, to become even more beneficial.

Shared familial risk for type 2 diabetes mellitus and psychiatric disorders: a nationwide multigenerational genetics study.

BACKGROUND: Psychiatric disorders and type 2 diabetes mellitus (T2DM) are heritable, polygenic, and often comorbid conditions, yet knowledge about their potential shared familial risk is lacking. We used family designs and T2DM polygenic risk score (T2DM-PRS) to investigate the genetic associations between psychiatric disorders and T2DM. METHODS: We linked 659 906 individuals born in Denmark 1990-2000 to their parents, grandparents, and aunts/uncles using population-based registers. We compared rates of T2DM in relatives of children with and without a diagnosis of any or one of 11 specific psychiatric disorders, including neuropsychiatric and neurodevelopmental disorders, using Cox regression. In a genotyped sample (iPSYCH2015) of individuals born 1981-2008 (n = 134 403), we used logistic regression to estimate associations between a T2DM-PRS and these psychiatric disorders. RESULTS: Among 5 235 300 relative pairs, relatives of individuals with a psychiatric disorder had an increased risk for T2DM with stronger associations for closer relatives (parents:hazard ratio = 1.38, 95% confidence interval 1.35-1.42; grandparents: 1.14, 1.13-1.15; and aunts/uncles: 1.19, 1.16-1.22). In the genetic sample, one standard deviation increase in T2DM-PRS was associated with an increased risk for any psychiatric disorder (odds ratio = 1.11, 1.08-1.14). Both familial T2DM and T2DM-PRS were significantly associated with seven of 11 psychiatric disorders, most strongly with attention-deficit/hyperactivity disorder and conduct disorder, and inversely with anorexia nervosa. CONCLUSIONS: Our findings of familial co-aggregation and higher T2DM polygenic liability associated with psychiatric disorders point toward shared familial risk. This suggests that part of the comorbidity is explained by shared familial risks. The underlying mechanisms still remain largely unknown and the contributions of genetics and environment need further investigation.

Maternal inflammation during pregnancy is associated with risk of ADHD in children at age 10.

INTRODUCTION: Maternal inflammation during pregnancy may affect early neurodevelopment in offspring as suggested by preclinical and register data. However, clinical evidence for risk of aberrant neurodevelopment later in childhood is scarce. In the population-based COPSAC2010 mother-child cohort, we investigated associations between maternal inflammation levels during pregnancy and the risk of a diagnosis of ADHD as well as the load of ADHD symptoms in the children at age 10. METHODS: The COPSAC2010 cohort consists of 700 mother-child pairs followed prospectively since pregnancy week 24.Maternal high-sensitivity C-Reactive Protein (hs-CRP) level at week 24 of gestation was investigated in relation to child neurodevelopment by age 10 using logistic and linear regression models with extensive confounder adjustment, including socioeconomic status and maternal polygenic risk of ADHD. The children completed a comprehensive examination of neurodevelopment including categorical (i.e., diagnostic) and dimensional (i.e., symptom load) psychopathology using the Kiddie Schedule for Affective Disorders and Schizophrenia Present and Lifetime Version (K-SADS-PL) and parental rated ADHD-Rating Scale (ADHD-RS). RESULTS: A total of 604 (86 %) of the 700 children in the COPSAC2010 cohort participated in the COPSYCH visit at age 10. Sixty-five (10.8 %) fulfilled a research diagnosis of ADHD (16 girls and 49 boys). Higher maternal hs-CRP level in pregnancy at week 24 (median 5.4 mg/L) was significantly associated with increased risk for a diagnosis of ADHD, adjusted OR 1.40, 95 %CI (1.16-1.70), p = 0.001. Additionally, higher maternal hs-CRP was associated with increased ADHD symptom load in the entire cohort, reflected by ADHD-RS raw scores. DISCUSSION: These clinical data demonstrated a robust association of prenatal maternal inflammation assessed by hs-CRP with a diagnosis of ADHD by age 10. Moreover, maternal inflammation was associated with ADHD symptom load in the complete cohort. Identifying inflammation as an important marker will provide a potential target for future increased awareness and prevention during pregnancy thereby ultimately improving neurodevelopmental outcomes in children.

A comprehensive analysis of age of onset and cumulative incidence of mental disorders: A Danish register study.

BACKGROUND: The age of onset (AOO), incidence and cumulative incidence of mental disorders are critical epidemiological measures, providing essential insights into the development and course of these disorders across the lifespan. This study aims to provide up-to-date estimates of the AOO, age-specific incidence, and cumulative incidence for a comprehensive range of mental disorders using data from Danish registers. METHODS: We conducted a follow-up study encompassing all Danish residents from January 1, 2004, to December 31, 2021, totaling 91,613,465 person-years. Data were sourced from the Danish Psychiatric Central Research Register, identifying individuals treated for various mental disorders in psychiatric hospitals, outpatient departments, and accident/emergency departments, that is, treated in secondary care settings. We investigated specific categories of mental disorders, including substance abuse disorders, schizophrenia, mood disorders, anxiety, eating disorders, borderline personality disorders, intellectual disabilities, pervasive developmental disorders, and behavioral and emotional disorders. Age-sex-specific incidence rates were estimated using Poisson generalized linear models, and cumulative incidence was calculated using Aalen-Johansen's competing risks model. The study provides estimates of AOO, incidence, and cumulative incidence for various mental disorders, including their age and sex distributions. RESULTS: The cumulative incidence by age 80 years for any mental disorder was 30.72% (95% confidence interval: 30.62%-30.83%) for males and 34.46% (34.35%-34.57%) for females. The most common types of mental disorders were anxiety-related disorders 16.27% (16.19%-16.36%) for males and 23.39% (23.29%-23.50%) for females, and followed by mood disorder 10.34% (10.27%-10.41%) for males and 16.67% (16.58%-16.77%) for females. For those who develop mental disorder, half will have developed their disorder by approximately age 22 years (median and interquartile range: males 21.37 (11.85-36.00); females 22.55 (16.31-36.08)). CONCLUSIONS: Approximately one in three individuals will seek treatment for at least one mental disorder in a secondary care setting by age 80. Given that half of these individuals develop mental disorders before age 22, it is crucial to tailor service planning to meet the specific needs of young individuals. Web-based interactive data-visualization tools are provided for clinical utility.

Do maternal anxiety and depressive symptoms predict anxiety in children with and without ADHD at 8 years?

Maternal anxiety and depression during pregnancy and early childhood have been associated with child anxiety and attention-deficit/hyperactivity disorder (ADHD). However, previous studies are limited by their short follow-up, few assessments of maternal symptoms, and by not including maternal and child ADHD. The present study aimed to fill these gaps by investigating whether maternal anxiety and depressive symptoms from pregnancy to child age 5 years increase the risk of child anxiety disorders at age 8 years. This study is part of the population-based Norwegian Mother, Father, and Child Cohort Study. Maternal anxiety and depressive symptoms were assessed by the Hopkins Symptom Checklist (SCL) six times from pregnancy through early childhood, and ADHD symptoms by the Adult Self-Report Scale (ASRS). At age 8 years (n = 781), symptoms of anxiety disorders and ADHD were assessed, and disorders classified by the Child Symptom Inventory-4. Logistic regression models estimated the risk of child anxiety depending on maternal symptoms. The mothers of children classified with an anxiety disorder (n = 91) scored significantly higher on the SCL (at all time points) and ASRS compared with the other mothers. In univariable analyses, maternal anxiety and/or depression and ADHD were associated with increased risk of child anxiety (odds ratios = 2.99 and 3.64, respectively), remaining significant in the multivariable analysis adjusted for covariates. Our findings link maternal anxiety, depression, and ADHD during pregnancy and early childhood to child anxiety at age 8 years.

Cognitive training for children with ADHD: composite cognitive score outcome in a randomized controlled trial.

PURPOSE OF THE ARTICLE: Cognitive training for Attention Deficit/Hyperactivity Disorder (ADHD) has shown promising, although mixed results. In post-hoc analyses, we evaluate effects of cognitive training using a novel composite cognition score as the outcome for children attending at least 16 sessions of training, dose-response of training and associations between symptoms and cognitive functioning. MATERIALS AND METHODS: Children (age 6-13) with ADHD were randomized to intervention (n = 26) or control (n = 34). For the current analysis, we restricted the intervention group to children, who completed at least 16 sessions of cognitive training (n = 26) and examined a dose response within that group. RESULTS: Cognition improved significantly in the intervention, but not control group. Amount of the completed training sessions correlated significantly with the amount of cognitive improvement. CONCLUSION: Variations in dose and frequency of training may be an important source of the variance in previous studies.

Association between Mental Disorders and Subsequent Medical Conditions.

BACKGROUND: Persons with mental disorders are at a higher risk than the general population for the subsequent development of certain medical conditions. METHODS: We used a population-based cohort from Danish national registries that included data on more than 5.9 million persons born in Denmark from 1900 through 2015 and followed them from 2000 through 2016, for a total of 83.9 million person-years. We assessed 10 broad types of mental disorders and 9 broad categories of medical conditions (which encompassed 31 specific conditions). We used Cox regression models to calculate overall hazard ratios and time-dependent hazard ratios for pairs of mental disorders and medical conditions, after adjustment for age, sex, calendar time, and previous mental disorders. Absolute risks were estimated with the use of competing-risks survival analyses. RESULTS: A total of 698,874 of 5,940,299 persons (11.8%) were identified as having a mental disorder. The median age of the total population was 32.1 years at entry into the cohort and 48.7 years at the time of the last follow-up. Persons with a mental disorder had a higher risk than those without such disorders with respect to 76 of 90 pairs of mental disorders and medical conditions. The median hazard ratio for an association between a mental disorder and a medical condition was 1.37. The lowest hazard ratio was 0.82 for organic mental disorders and the broad category of cancer (95% confidence interval [CI], 0.80 to 0.84), and the highest was 3.62 for eating disorders and urogenital conditions (95% CI, 3.11 to 4.22). Several specific pairs showed a reduced risk (e.g., schizophrenia and musculoskeletal conditions). Risks varied according to the time since the diagnosis of a mental disorder. The absolute risk of a medical condition within 15 years after a mental disorder was diagnosed varied from 0.6% for a urogenital condition among persons with a developmental disorder to 54.1% for a circulatory disorder among those with an organic mental disorder. CONCLUSIONS: Most mental disorders were associated with an increased risk of a subsequent medical condition; hazard ratios ranged from 0.82 to 3.62 and varied according to the time since the diagnosis of the mental disorder. (Funded by the Danish National Research Foundation and others; COMO-GMC ClinicalTrials.gov number, NCT03847753.).

High polygenic predisposition for ADHD and a greater risk of all-cause mortality: a large population-based longitudinal study.

BACKGROUND: Attention deficit hyperactivity disorder (ADHD) is a highly heritable, neurodevelopmental disorder known to associate with more than double the risk of death compared with people without ADHD. Because most research on ADHD has focused on children and adolescents, among whom death rates are relatively low, the impact of a high polygenic predisposition to ADHD on accelerating mortality risk in older adults is unknown. Thus, the aim of the study was to investigate if a high polygenetic predisposition to ADHD exacerbates the risk of all-cause mortality in older adults from the general population in the UK. METHODS: Utilising data from the English Longitudinal Study of Ageing, which is an ongoing multidisciplinary study of the English population aged ≥ 50 years, polygenetic scores for ADHD were calculated using summary statistics for (1) ADHD (PGS-ADHDsingle) and (2) chronic obstructive pulmonary disease and younger age of giving first birth, which were shown to have a strong genetic correlation with ADHD using the multi-trait analysis of genome-wide association summary statistics; this polygenic score was referred to as PGS-ADHDmulti-trait. All-cause mortality was ascertained from the National Health Service central register that captures all deaths occurring in the UK. RESULTS: The sample comprised 7133 participants with a mean age of 64.7 years (SD = 9.5, range = 50-101); of these, 1778 (24.9%) died during a period of 11.2 years. PGS-ADHDsingle was associated with a greater risk of all-cause mortality (hazard ratio [HR] = 1.06, 95% CI = 1.02-1.12, p = 0.010); further analyses showed this relationship was significant in men (HR = 1.07, 95% CI = 1.00-1.14, p = 0.043). Risk of all-cause mortality increased by an approximate 11% for one standard deviation increase in PGS-ADHDmulti-trait (HR = 1.11, 95% CI = 1.06-1.16, p < 0.001). When the model was run separately for men and women, the association between PGS-ADHDmulti-trait and an increased risk of all-cause mortality was significant in men (HR = 1.10, 95% CI = 1.03-1.18, p = 0.003) and women (HR = 1.11, 95% CI = 1.04-1.19, p = 0.003). CONCLUSIONS: A high polygenetic predisposition to ADHD is a risk factor for all-cause mortality in older adults. This risk is better captured when incorporating genetic information from correlated traits.

Behavioural side effects of inhaled corticosteroids among children and adolescents with asthma.

BACKGROUND: Inhalation corticosteroids (ICS) are prescribed for treatment of asthma in approximately 3% of all children in Denmark. Despite limited evidence, case reports suggest that ICS-related behavioural adverse drug events (ADEs) may be frequent. In general, underreporting of ADEs to official databases is common, and little is known about doctor's clinical experiences with behavioural ADEs when prescribing ICS for children with asthma. The objective was to investigate the extent of behavioural ADEs in children with asthma treated with ICS by comparing database findings to experiences of specialist doctors. METHODS: First, databases of the European Medicines Agency (EMA) and the Danish Medicines Agency (DKMA) were searched for reports made by healthcare professionals about behavioural ADEs in children from 2009 to 2018. Second, questionnaire data on behavioural ADEs were collected from eight of the 11 specialist doctors responsible for treating children with asthma at the six paediatric departments in Central Denmark Region and North Denmark Region. RESULTS: EMA and DKMA had registered 104 and 3 reports, respectively, on behavioural ADEs during the 10-year study period. In contrast, five of the eight specialist doctors (45.5%) had experienced patients who had developed behavioural changes during ICS treatment. However, none of the five specialist doctors had filed reports on these events to DKMA. CONCLUSION: Behaviour-related ADEs to ICS in children with asthma are likely to be highly underreported in official databases and doctors treating children with ICS should be aware of potential ADEs and consider submitting ADE reports whenever appropriate.

Temporal changes in sex- and age-specific incidence profiles of mental disorders-A nationwide study from 1970 to 2016.

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.

Temporally ordered associations between type 2 diabetes and brain disorders - a Danish register-based cohort study.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is linked with several neurodegenerative and psychiatric disorders, either as a comorbid condition or as a risk factor. We aimed to expand the evidence by examining associations with a broad range of brain disorders (psychiatric and neurological disorders, excluding late-onset neurodegenerative disorders), while also accounting for the temporal order of T2DM and these brain disorders. METHODS: In a population-based cohort-study of 1,883,198 Danish citizens, born 1955-1984 and followed until end of 2016, we estimated associations between T2DM and 16 brain disorders first diagnosed between childhood and mid-adulthood. We calculated odds ratios (OR) and hazard ratios (HR) with 95% confidence intervals (CI) in temporally ordered analyses (brain disorder diagnosis after T2DM and vice versa), adjusted for sex, age, follow-up, birth year, and parental factors. RESULTS: A total of 67,660 (3.6%) of the study population were identified as T2DM cases after age 30 and by a mean age of 45 years (SD of 8 years). T2DM was associated with most psychiatric disorders. Strongest associations were seen with other (i.e. non-anorectic) eating disorders (OR [95% CI]: 2.64 [2.36-2.94]) and schizophrenia spectrum disorder (2.73 [2.63-2.84]). Among neurological disorders especially inflammatory brain diseases (1.73 [1.57-1.91]) and epilepsy (1.67 [1.60-1.75]) were associated with T2DM. Most associations remained in both directions in the temporally ordered analyses. For most psychiatric disorders, associations were strongest in females. CONCLUSIONS: T2DM was associated with several psychiatric and neurological disorders, and most associations were consistently found for both temporal order of disorders. This suggests a shared etiology of T2DM and those brain disorders. This study can form the starting point for studies directed at further elucidating potential causal links between disorders and shared biological mechanisms.

No evidence of associations between genetic liability for schizophrenia and development of cannabis use disorder.

BACKGROUND: Cannabis use and cannabis use disorder (CUD) is increased in patients with schizophrenia. It is important to establish if this is explained by non-causal factors, such as shared genetic vulnerability. We aimed to investigate whether the polygenic risk scores (PRS) for schizophrenia and other psychiatric disorders would predict CUD in controls, patients with schizophrenia, and patients with other psychiatric disorders. METHODS: We linked nationwide Danish registers and genetic information obtained from dried neonatal bloodspots in an observational analysis. We included people with schizophrenia, other psychiatric disorders, and controls. The exposures of interest were the PRS for schizophrenia, attention-deficit hyperactivity disorder (ADHD) autism spectrum disorder, and anorexia nervosa. The main outcome of interest was the diagnosis of CUD. RESULTS: The study included 88 637 individuals. PRS for schizophrenia did not predict CUD in controls [hazard ratio (HR) = 1.16, 95% CI 0.95-1.43 per standard-deviation increase in PRS, or HR = 1.47, 95% CI 0.72-3.00 comparing highest v. remaining decile], but PRS for ADHD did (HR = 1.27, 95% CI 1.08-1.50 per standard-deviation increase, or HR = 2.02, 95% CI 1.27-3.22 for the highest decile of PRS). Among cases with schizophrenia, the PRS for schizophrenia was associated with CUD. While CUD was a strong predictor of schizophrenia (HR = 4.91, 95% CI 4.36-5.53), the inclusion of various PRS did not appreciably alter this association. CONCLUSION: The PRS for schizophrenia was not associated with CUD in controls or patients with other psychiatric disorders than schizophrenia. This speaks against the hypothesis that shared genetic vulnerability would explain the association between cannabis and schizophrenia.

Infectious mononucleosis as a risk factor for depression: A nationwide cohort study.

BACKGROUND: Infectious mononucleosis is a clinical diagnosis characterized by fever, sore throat, lymph node enlargement and often prolonged fatigue, most commonly caused by Epstein-Barr virus infection. Previous studies have indicated that infectious mononucleosis can be followed by depression; however, large-scale studies are lacking. We used nationwide registry data to investigate the association between infectious mononucleosis and subsequent depression in this first large-scale study. METHODS: Prospective cohort study using nationwide Danish registers covering all 1,440,590 singletons born (1977-2005) in Denmark by Danish born parents (21,830,542 person-years' follow-up until 2016); where 12,510 individuals had a hospital contact with infectious mononucleosis. The main outcome measures were a diagnosis of major depressive disorder (ICD-8: 296.09, 298.09, 300.4; ICD-10: F32) requiring hospital contact. RESULTS: Infectious mononucleosis was associated with a 40% increased hazard ratio (HR) for a subsequent depression diagnosis in the fully adjusted model (HR: 1.40, 95% CI: 1.26-1.56;n = 358), when compared to unexposed individuals. The increased risk of being diagnosed with depression was significant to the periods one to four years after the infectious mononucleosis diagnosis (HR: 1.40, 95% CI: 1.17-1.67;n = 121) and ≥ five years (HR: 1.40, 95% CI: 1.22-1.61;n = 207). We did not find any differences according to age (p = 0.61) nor sex (p = 0.30). CONCLUSION: In this largest study to date, infectious mononucleosis in childhood or adolescence was associated with an increased risk of a subsequent depression. Our findings have important clinical implications and identifies youth with infectious mononucleosis as a group at high risk of later depression in young adulthood.

Cumulative incidence and relative risk of sleep problems among children and adolescents with newly diagnosed neurodevelopmental disorders: A nationwide register-based study.

We estimated the absolute and relative risk of sleep problems in children and adolescents with newly diagnosed neurodevelopmental disorders. This was a population-based cohort study of individuals born in Denmark in 1993-2014 and followed in nationwide registers in 2011-2016. We estimated the 5-year cumulative incidence of sleep problems in incident cases of attention-deficit/hyperactivity disorder (ADHD; n = 12,844), autism spectrum disorder (ASD; n = 8,073), oppositional defiant disorder/conduct disorder (ODD/CD; n = 2,234) and epilepsy (n = 3,709). Hazard ratios (HRs) for sleep problems were estimated by Cox regression. The 5-year risk of sleep problems was highest in ADHD (29.2%; 95% CI, 28.4-30.1), ASD (24.2%; 95% CI, 23.1-25.3) and ODD/CD (27.1% 95% CI, 25.0%-29.2%) and lowest in epilepsy (11.3%; 95% CI, 10.2%-12.6%). For ADHD and ASD, sleep problems were more common in females than in males. Furthermore, sleep problems were predicted by high parental socioeconomic status and varied with the geographical region of residence, suggesting that different clinical practices exist across Denmark and that sleep problems may be more likely to go undetected in families of lower socioeconomic position. Compared with individuals without these disorders, the likelihood of sleep problems was increased in individuals with ADHD (HR, 33.81; 95% CI, 32.78-34.87), ASD (HR, 16.77; 95% CI, 16.15-17.41), ODD/CD (HR, 14.73; 95% CI, 13.88-15.64) and epilepsy (HR, 6.01; 95% CI, 5.67-6.37). After mutual adjustment for comorbidity, HRs were attenuated, especially in ASD, ODD/CD and epilepsy when adjusted for ADHD, suggesting that the increased risk of sleep problems in individuals with ASD, ODD/CD and epilepsy is driven largely by comorbid ADHD.

[International Consensus Statement for the Screening, Diagnosis, and Treatment of Adolescents with Concurrent Attention-Deficit/Hyperactivity Disorder and Substance Use Disorder]. / Internationale Konsenserklärung zu Screening, Diagnostik und Behandlung von Jugendlichen und Heranwachsenden mit Aufmerksamkeitsdefizit-/Hyperaktivitätsstörung und gleichzeitigen Störungen durch Substanzgebrauch.

International Consensus Statement for the Screening, Diagnosis, and Treatment of Adolescents with Concurrent Attention-Deficit/Hyperactivity Disorder and Substance Use Disorder Abstract. Background: Childhood attention-deficit/hyperactivity disorder (ADHD) is a risk factor for substance misuse and substance use disorder (SUD) in adolescence and (early) adulthood. ADHD and SUD also frequently co-occur in treatment-seeking adolescents, which complicates diagnosis and treatment and is associated with poor treatment outcomes. Research on the effect of treatment of childhood ADHD on the prevention of adolescent SUD is inconclusive, and studies on the diagnosis and treatment of adolescents with ADHD and SUD are scarce. Thus, the available evidence is generally not sufficient to justify robust treatment recommendations. Objective: The aim of the study was to obtain a consensus statement based on a combination of scientific data and clinical experience. Method: A modified Delphi study to reach consensus based upon the combination of scientific data and clinical experience with a multidisciplinary group of 55 experts from 17 countries. The experts were asked to rate a set of statements on the effect of treatment of childhood ADHD on adolescent SUD and on the screening, diagnosis, and treatment of adolescents with comorbid ADHD and SUD. Results: After 3 iterative rounds of rating and adapting 37 statements, consensus was reached on 36 of these statements representing 6 domains: general (n = 4), risk of developing SUD (n = 3), screening and diagnosis (n = 7), psychosocial treatment (n = 5), pharmacological treatment (n = 11), and complementary treatments (n = 7). Routine screening is recommended for ADHD in adolescent patients in substance abuse treatment and for SUD in adolescent patients with ADHD in mental healthcare settings. Long-acting stimulants are recommended as the first-line treatment of ADHD in adolescents with concurrent ADHD and SUD, and pharmacotherapy should preferably be embedded in psychosocial treatment. The only remaining no-consensus statement concerned the requirement of abstinence before starting pharmacological treatment in adolescents with ADHD and concurrent SUD. In contrast to the majority, some experts required full abstinence before starting any pharmacological treatment, some were against the use of stimulants in the treatment of these patients (independent of abstinence), while some were against the alternative use of bupropion. Conclusion: This international consensus statement can be used by clinicians and patients together in a shared decision-making process to select the best interventions and to reach optimal outcomes in adolescent patients with concurrent ADHD and SUD.

Exposure to air pollution in early childhood and the association with Attention-Deficit Hyperactivity Disorder.

BACKGROUND: Exposure to air pollution in early life has been linked to cognitive deficits and adverse neurodevelopmental effects. However, studies examining associations between air pollutants and Attention-Deficit/Hyperactivity Disorder (ADHD) have had conflicting findings. METHODS: Individuals born in Denmark 1992-2007 (n = 809,654) were followed for the development of ADHD from 1997 to 2013. Data on daily concentrations of nitrogen dioxide (NO2) and fine particulate matter (PM2.5) from air-modeling data at a 1 km × 1 km resolution at residences within the first five years of life, was linked with population-based data from the Danish national registers, including data on clinical diagnoses of ADHD. We estimated incidence rate ratios (IRRs) with 95% confidence intervals (CI) for ADHD, according to increases in exposures, adjusting for age, year, sex, and parental education and income. RESULTS: Exposure to NO2 and PM2.5 during early life was associated with a significantly increased risk of ADHD: IRR of 1.38 (Cl: 1.35 to 1.42) per 10 µg/m3 increase in NO2 and an IRR of 1.51 (Cl: 1.41 to 1.62) per 5 µg/m3 increase in PM2.5. In two-pollutant models, the association between NO2 and ADHD did not change (IRR 1.35; 95% CI: 1.31 to 1.39), while the association with PM2.5 was substantially attenuated (IRR 1.07; 95% CI: 0.98 to 1.16), although in stratified models an elevated association with PM2.5 was found in the lowest quintile of NO2 exposure. CONCLUSIONS: In this large nationwide prospective cohort study, residential air pollution exposure, specifically NO2, during early childhood was associated with the development of ADHD, even when adjusted for parental level of income and education.

International Consensus Statement for the Screening, Diagnosis, and Treatment of Adolescents with Concurrent Attention-Deficit/Hyperactivity Disorder and Substance Use Disorder.

BACKGROUND: Childhood attention-deficit/hyperactivity disorder (ADHD) is a risk factor for substance misuse and substance use disorder (SUD) in adolescence and (early) adulthood. ADHD and SUD also frequently co-occur in treatment-seeking adolescents, which complicates diagnosis and treatment and is associated with poor treatment outcomes. Research on the effect of treatment of childhood ADHD on the prevention of adolescent SUD is inconclusive, and studies on the diagnosis and treatment of adolescents with ADHD and SUD are scarce. Thus, the available evidence is generally not sufficient to justify robust treatment recommendations. OBJECTIVE: The aim of the study was to obtain a consensus statement based on a combination of scientific data and clinical experience. METHOD: A modified Delphi study to reach consensus based upon the combination of scientific data and clinical experience with a multidisciplinary group of 55 experts from 17 countries. The experts were asked to rate a set of statements on the effect of treatment of childhood ADHD on adolescent SUD and on the screening, diagnosis, and treatment of adolescents with comorbid ADHD and SUD. RESULTS: After 3 iterative rounds of rating and adapting 37 statements, consensus was reached on 36 of these statements representing 6 domains: general (n = 4), risk of developing SUD (n = 3), screening and diagnosis (n = 7), psychosocial treatment (n = 5), pharmacological treatment (n = 11), and complementary treatments (n = 7). Routine screening is recommended for ADHD in adolescent patients in substance abuse treatment and for SUD in adolescent patients with ADHD in mental healthcare settings. Long-acting stimulants are recommended as the first-line treatment of ADHD in adolescents with concurrent ADHD and SUD, and pharmacotherapy should preferably be embedded in psychosocial treatment. The only remaining no-consensus statement concerned the requirement of abstinence before starting pharmacological treatment in adolescents with ADHD and concurrent SUD. In contrast to the majority, some experts required full abstinence before starting any pharmacological treatment, some were against the use of stimulants in the treatment of these patients (independent of abstinence), while some were against the alternative use of bupropion. CONCLUSION: This international consensus statement can be used by clinicians and patients together in a shared decision-making process to select the best interventions and to reach optimal outcomes in adolescent patients with concurrent ADHD and SUD.

Suicidal behaviour among persons with attention-deficit hyperactivity disorder.

BACKGROUND: Persons diagnosed with attention-deficit hyperactivity disorder (ADHD) have been found to have an increased risk of suicidal behaviour, but the pathway remains to be thoroughly explored.AimsTo determine whether persons with ADHD are more likely to present with suicidal behaviour (i.e. suicide attempts and deaths by suicide) if they have a comorbid psychiatric disorder. METHOD: Using nationwide registers covering the entire population of Denmark, this cohort study of 2.9 million individuals followed from 1 January 1995 until 31 December 2014, covers more than 46 million person-years. All persons aged ≥10 years with Danish-born parents were identified and persons with a diagnosis of ADHD were compared with persons without. Incidence rate ratios (IRRs) were calculated by Poisson regression, with adjustments for sociodemographics and parental suicidal behaviour. RESULTS: Persons with ADHD were followed for 164 113 person-years and 697 suicidal outcomes were observed. This group was found to have an IRR of suicidal behaviour of 4.7 (95% CI, 4.3-5.1) compared with those without ADHD. Persons with ADHD only had a 4.1-fold higher rate (95% CI, 3.5-4.7) when compared with those without any psychiatric diagnoses. For persons with ADHD and comorbid disorders the IRR was higher yet (IRR: 10.4; 95% CI, 9.5-11.4). CONCLUSIONS: This study underlines the link between ADHD and an elevated rate of suicidal behaviour, which is significantly elevated by comorbid psychiatric disorders. In sum, these results suggest that persons with ADHD and comorbid psychiatric disorders are targets for suicide preventive interventions.Declaration of interestNone.

Parental asthma occurrence, exacerbations and risk of attention-deficit/hyperactivity disorder.

OBJECTIVE: To investigate whether intrauterine exposure to maternal asthma or asthma exacerbations increases the risk of attention-deficit/hyperactivity disorder (ADHD). METHODS: Using Danish register data, this cohort study comprised of 961,202 live singletons born in Denmark during 1997-2012. Children were followed to a maximum of 20.0 years from birth until the first of ADHD-diagnosis/prescription, emigration, death, or 31 December 2016. Cox regression models were used to evaluate the association between maternal or paternal asthma, asthma exacerbations and offspring ADHD. RESULTS: During 11.4 million person-years of follow-up, 27,780 (2.9%) children were identified as having ADHD. ADHD risk was increased among offspring born to asthmatic mothers (hazard ratio (HR) 1.41, 95% CI: 1.36-1.46) or asthmatic fathers (HR 1.13, 95% CI: 1.08-1.18). Antenatal antiasthma medication treatment did not increase offspring ADHD. However, higher risks were observed among offspring of mothers with asthma exacerbations compared with children of asthmatic mothers with no exacerbations: HR 1.12 (95% CI: 1.00-1.25) for pre-pregnancy exacerbations; 1.21 (95% CI: 1.00-1.47) for exacerbations during pregnancy; and 1.25 (95% CI: 1.08-1.44) for exacerbations after delivery. CONCLUSIONS: These results support theories regarding shared genetic and environmental risk factors having a role in the development of ADHD.

The effects of practicing target-shooting sport on the severity of inattentive, hyperactive, and impulsive symptoms in children: a non-randomised controlled open-label study in Denmark.

Purpose: Target-shooting sport requires mental effort and concentration. Training may reduce inattentiveness and distractibility. There is little knowledge if children with symptoms of attention-deficit/hyperactivity disorder (ADHD) benefit from practicing target-shooting sport. Materials and methods: Our study aims to investigate this in a non-randomised controlled open-label study of 128 children, 10-14 years of age, with ADHD-symptoms. The intervention-group (n = 64) practiced target-shooting in local shooting associations once a week for 6 months. The control group (n = 64) received treatment as usual. Primary outcome: teacher-rated ADHD-RS-IV-total score. Secondary outcomes: (a) parent-rated ADHD-RS-IV-total score; (b) teacher- and parent-rated Strengths-and-Difficulties-Questionnaire (SDQ); (c) self-rated quality of life (KIDSCREEN-27-total score); and (d) four objective measurements of ADHD-symptoms using the QbTest™. The data were collected at baseline and after 6 months. Results: When estimating the marginal effect of the intervention on our primary outcome, the teacher-rated ADHD-RS-IV, we found no significant effect (mean change between groups (contrast)=2.23; p = 0.193). However, we did find significant beneficial effects on four of the eight secondary outcomes, including the parent-rated ADHD-RS-IV-total score (contrast = 4.76; p = 0.024), the parent-rated SDQ-total score (contrast = 2.09; p = 0.027), and on the QbTest™ measurements of the Reaction Time Variation (RTVar) (contrast = 36.96; p = 0.013), and of Omission Errors (contrast = 7.57; p = 0.019). Conclusions: Despite the negative result on the primary outcome, the robust findings on these secondary outcomes in this open-label study indicate proof of concept that practicing target-shooting sport may have some beneficial effects on the severity of ADHD-symptoms in children. No adverse events were reported. Randomised trials of this non-pharmacological intervention are needed.