Duration and timing of depression and risk of family dissolution: A register-based cohort study of newly-formed Danish families.

BACKGROUND: Depression is detrimental to partnership stability. However, it remains unclear if and how the duration and timing of depression affect the risk of family dissolution. METHODS: We conducted a Danish register-based cohort study of newly-formed cohabiting and married couples in 2008 and 2009, who were followed from the second year after family formation. Depressive episodes were defined by individual-level prescription patterns of antidepressant drugs (ATC codes N06A) in either partner. Family dissolution was characterized by the discontinuation of a shared residential address. Using Longitudinal Targeted Minimum Loss-based Estimation, we estimated the risk of family dissolution after 5 years of follow-up under various lengths and timings of depressive episodes. RESULTS: There were 102,335 families included. The covariate-adjusted risk of family dissolution in families without depressive episodes was 30.0 % (95 % CI 29.6-30.4 %) and 35.5 % (95 % CI 29.5-41.5 %) in families with at least one depressive episode during follow-up. The risk of family dissolution increased with the duration of depressive episodes to 42.2 % (95 % CI 40.8-43.6 %) for five coherent years of depression. Depression shortly after family formation carried higher risk of family dissolution; this risk was 42.3 % (95 % CI 38.4-46.3 %) for depression experienced in the first year of family formation versus 32.9 % (95 % CI 31.8-34.0 %) in the fifth year of family formation. LIMITATIONS: Proxy measures of depression by antidepressant prescriptions fails to identify milder depression. Annual measures of family dissolution precluded more fine-grained analyses of time-intervals. CONCLUSIONS: Depression is disruptive to family stability, particularly with longer duration and early onset after family formation.

Distinct age-related differences among victims in cases of suspected child abuse.

Evidence describing age-related differences among children with suspected physical and sexual child abuse is lacking. We describe findings in severe cases of suspected abuse. Cases with 756 children <15 years old were included during 2001-2013 at the Department of Forensic Medicine, Aarhus University, using forensic evaluation documents, medical records, and court proceedings. Eight percent of children <4 years old died from child abuse, 36% through violence resulting in death, and 64% by manslaughter, whereas 1% > 4 years old died, solely by manslaughter. External injuries were mainly located to head and torso in children <4 years old, changing to the upper and lower extremities in older children. Child sexual abuse was suspected in 52% of cases with living children <4 years old, 83% of children 4-7 years of age, 88% of children 8-11 years of age, and 93% of children >12 years old. Anogenital findings were mainly caused by other medical conditions in children <4 years old, hymenal clefts in the superior half of the hymenal rim were almost exclusively found in children between 8 and 11 years of age, whereas both superficial and complete hymenal clefts in the inferior half of the hymenal rim were found in children >12 years old. The present study describes age-related differences in victims of suspected child abuse. Fatal versus nonfatal child physical abuse and the significance of hymenal findings in child sexual abuse could be studied further.

Prenatal antidepressant exposure and the risk of decreased gestational age and lower birthweight: A polygenic score approach to investigate confounding by indication.

INTRODUCTION: Prenatal antidepressant exposure has been associated with lower gestational age and birthweight. Yet, unmeasured residual confounding may inflate this association. We explored if maternal genetic liability for major depression explains part of the association of antidepressant use in pregnancy with lower gestational age and birthweight. MATERIAL AND METHODS: We employed the maternal polygenic score (PGS) for major depression as a measure of genetic liability. We used generalised linear models to estimate the differences in gestational age and birthweight at each PGS quintile between children whose mothers continued antidepressant use during pregnancy (continuation group), children whose mothers discontinued antidepressant use during pregnancy (discontinuation group) and unexposed children. RESULTS: After adjusting for confounders, we found significant differences in birthweight between PGS quintiles in the continuation and unexposed group. Yet, this relationship was not linear. Furthermore, at the lowest and highest PGS quintiles, the continuation group had significantly reduced mean gestational ages (adjusted ß ranges: 1.7-4.5 days, p < 0.001-0.008) and lower mean birthweights (adjusted ß ranges: 58.6-165.4 g, p = 0.001-0.008) than the discontinuation and unexposed groups. CONCLUSION: We confirmed that antidepressant use in pregnancy was associated with small reductions in gestational age and birthweight but found that genetic liability for depression was not linearly associated with this risk. The causality of the observed associations could not be established due to the observational nature of the study. Residual confounding linked to the underlying disease was likely still present.

Identification of women at high risk of postpartum psychiatric episodes: A population-based study quantifying relative and absolute risks following exposure to selected risk factors and genetic liability.

BACKGROUND: We quantified relative and absolute risks of postpartum psychiatric episodes (PPE) following risk factors: Young age, past personal or family history of psychiatric disorders, and genetic liability. METHODS: We conducted a register-based study using the iPSYCH2012 case-cohort sample. Exposures were personal history of psychiatric episodes prior to childbirth, being a young mother (giving birth before the age of 21.5 years), having a family history of psychiatric disorders, and a high (highest quartile) polygenic score (PGS) for major depression. PPE was defined within 12 months postpartum by prescription of psychotropic medication or in- and outpatient contact to a psychiatric facility. We included primiparous women born 1981-1999, giving birth before January 1st, 2016. We conducted Cox regression to calculate hazard ratios (HRs) of PPE, absolute risks were calculated using cumulative incidence functions. RESULTS: We included 8174 primiparous women, and the estimated baseline PPE risk was 6.9% (95% CI 6.0%-7.8%, number of PPE cases: 2169). For young mothers with a personal and family history of psychiatric disorders, the absolute risk of PPE was 21.6% (95% CI 15.9%-27.8%). Adding information on high genetic liability to depression, the risk increased to 29.2% (95% CI 21.3%-38.4%) for PPE. CONCLUSIONS: Information on prior personal and family psychiatric episodes as well as age may assist in estimating a personalized risk of PPE. Furthermore, additional information on genetic liability could add even further to this risk assessment.

The association between mental disorders and subsequent years of working life: a Danish population-based cohort study.

BACKGROUND: Mental disorders can affect workforce participation via a range of mechanisms. In this study, we aimed to estimate the association between different types of mental disorders and working years lost, defined as the number of years not actively working or enrolled in an educational programme. METHODS: In this population-based cohort study, we included all people aged 18-65 years (mean 38·0 [SD 13·9]) in the Danish Civil Registration System from Jan 1, 1995 to Dec 31, 2016. Information on mental disorders was obtained from the Danish Psychiatric Central Research Register and information on labour market characteristics was obtained from administrative registers. Follow-up started at age 18 years, immigration to Denmark, or on Jan 1, 1995, whichever came later; and it ended at age 65 years, death, emigration from Denmark, disability pension, voluntary early retirement, or Dec 31, 2016 (whichever came earlier). As the main outcome, we estimated working years lost for those diagnosed with any mental disorder and 24 types of mental disorders, as well as for the general population of same age and sex. We decomposed total working years lost into periods of unemployment or sick leave, disability pension, voluntary early retirement, or death. Data on ethnicity were not available through administrative registers. FINDINGS: A total of 5 163 321 individuals, 2 642 383 men and 2 520 938 women, were followed up for 65·4 million person-years. Overall, 488 775 (9·47%) individuals were diagnosed with a mental disorder. On average, individuals with mental disorders lost an additional 10·52 (95% CI 10·48-10·57) years of working life compared with the general Danish population. Receiving a disability pension (7·54 [7·49-7·59] years) and longer periods of unemployment (2·24 [2·21-2·27] years) accounted for most of this difference. INTERPRETATION: Our findings foreground the substantial impact of mental disorders on workforce participation. There is a need to invest in programmes that reduce the burden of working years lost and assist people with mental disorders in returning to the workforce. FUNDING: Lundbeck Foundation and Danish National Research Foundation.

Postpartum depression: a developed and validated model predicting individual risk in new mothers.

Postpartum depression (PPD) is a serious condition associated with potentially tragic outcomes, and in an ideal world PPDs should be prevented. Risk prediction models have been developed in psychiatry estimating an individual's probability of developing a specific condition, and recently a few models have also emerged within the field of PPD research, although none are implemented in clinical care. For the present study we aimed to develop and validate a prediction model to assess individualized risk of PPD and provide a tentative template for individualized risk calculation offering opportunities for additional external validation of this tool. Danish population registers served as our data sources and PPD was defined as recorded contact to a psychiatric treatment facility (ICD-10 code DF32-33) or redeemed antidepressant prescriptions (ATC code N06A), resulting in a sample of 6,402 PPD cases (development sample) and 2,379 (validation sample). Candidate predictors covered background information including cohabitating status, age, education, and previous psychiatric episodes in index mother (Core model), additional variables related to pregnancy and childbirth (Extended model), and further health information about the mother and her family (Extended+ model). Results indicated our recalibrated Extended model with 14 variables achieved highest performance with satisfying calibration and discrimination. Previous psychiatric history, maternal age, low education, and hyperemesis gravidarum were the most important predictors. Moving forward, external validation of the model represents the next step, while considering who will benefit from preventive PPD interventions, as well as considering potential consequences from false positive and negative test results, defined through different threshold values.

Family History of Psychiatric Disorders as a Risk Factor for Maternal Postpartum Depression: A Systematic Review and Meta-analysis.

Importance: Current evidence on the association between family history of psychiatric disorders and postpartum depression is inconsistent; family studies have identified familial risk of postpartum depression, whereas systematic reviews and umbrella reviews, compiling all risk factors for postpartum depression, often have not. Objective: To investigate the association between family history of psychiatric disorders and risk of developing postpartum depression within 12 months post partum. Data Sources: Literature searches were conducted in PubMed, Embase, and PsycINFO in September 2021 and updated in March 2022, accompanied by citation and reference search. Study Selection: Studies eligible for inclusion comprised peer-reviewed cohort and case-control studies reporting an odds ratio (OR) or sufficient data to calculate one for the association between family history of any psychiatric disorder and postpartum depression. Study selection was made by 2 independent reviewers: title and abstract screening followed by full-text screening. Data Extraction and Synthesis: Reporting was performed using the MOOSE checklist. Two reviewers independently extracted predefined information and assessed included studies for risk of bias using the Newcastle-Ottawa Scale. Data were pooled in a meta-analysis using a random-effects model. Heterogeneity was investigated with meta-regression, subgroup, and sensitivity analyses. Publication bias was investigated using a funnel plot, and GRADE (Grading of Recommendations Assessment, Development, and Evaluation) was used to evaluate the overall certainty of the findings. Main Outcomes and Measures: The primary outcome was the pooled association between family history of psychiatric disorders and postpartum depression. Results: A total of 26 studies were included, containing information on 100 877 women. Meta-analysis showed an increased OR of developing postpartum depression when mothers had a family history of psychiatric disorders (OR, 2.08; 95% CI, 1.67-2.59; I2 = 57.14%) corresponding to a risk ratio of 1.79 (95% CI, 1.52-2.09), assuming a 15% postpartum depression prevalence in the general population. Subgroup, sensitivity, and meta-regression analyses were in line with the primary analysis. The overall certainty of evidence was deemed as moderate according to GRADE. Conclusions and Relevance: In this study, there was moderate certainty of evidence for an almost 2-fold higher risk of developing postpartum depression among mothers who have a family history of any psychiatric disorder compared with mothers without.

Family history of psychiatric disorders as a risk factor for maternal postpartum depression: a systematic review protocol.

BACKGROUND: Postpartum depression (PPD) is the most common postpartum psychiatric disorder, affecting 11-15% of new mothers, and initiatives towards early identification and treatment are essential due to detrimental consequences. Family history of psychiatric disorders is a risk factor for developing psychiatric episodes outside the postpartum period, but evidence of the association between familial risk and PPD is not clear. Hence, the objective of this systematic review is to summarize the current literature on the association between family history of psychiatric disorders and PPD. METHODS: This protocol has been developed and reported according to the PRISMA-P guidelines for systematic reviews. A comprehensive literature search will be conducted in PubMed, Embase, and PsycINFO from inception of the databases, supplemented with citation tracking and reference screening of the included studies. Two independent authors will examine all retrieved articles for inclusion in two steps: title/abstract screening and full-text screening. Eligible studies are case-control and cohort studies reporting a risk estimate for the association between family history of psychiatric disorders and PPD. Studies will be assessed for risk of bias using the Newcastle-Ottawa Scale. The association between family psychiatry and PPD will be combined in a meta-analysis using a restricted maximum likelihood method (REML). Heterogeneity will be quantified using I2 and investigated through meta-regression, subgroup and sensitivity analyses, and publication bias will be evaluated via visual inspection of a funnel plot. The overall strength and quality of the findings will be evaluated using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach. If meta-analysis is not possible, data will be synthesized narratively in text and tables. DISCUSSION: This systematic review will be the first to summarize current knowledge and present an overall estimate for the association between family history of psychiatric disorders and PPD. Evaluation of psychiatric family history as a PPD risk factor is essential to assist early identification of women at high risk of PPD in routine perinatal care. SYSTEMATIC REVIEW REGISTRATION: PROSPERO ID: 277998 (registered 10th of September 2021).

Treatment-resistant depression and labor market affiliation in the Danish welfare society: a register-based study.

PURPOSE: We explored if patients with treatment-resistant depression (TRD) go through different states of labor market affiliation during their course of illness before they return to work or obtain early retirement as compared to patients without TRD. METHODS: All adults between 18 and 58 years with a first-time hospital contact due to depression in Danish patients' registers from 2000 to 2014 were followed in a nationwide labor market database. At time of TRD (index week), TRD patients were matched with patients without TRD in a 1:2 ratio. Sequence analysis and logistic regression were applied to explore the association of TRD and labor market affiliation and measures of transitions between labor market states 52 weeks before and after the index week. RESULTS: At the index week, 14.1% of patients with TRD were in employment, whereas the proportion was 26.4% among non-TRD patients. Over time, the proportion of patients in employment increased slightly to 25.5% for TRD and 33.7% for non-TRD patients. The proportion of TRD patients with sickness absence at index was 47.0%, while the proportion was 26.2% for non-TRD patients. The adjusted odds of a below mean volatility of labor market transitions, characterized by more episodes in passive social transfer payments and disability pension, were higher among patients with TRD compared with non-TRD patients (OR 1.63, 95% CI [1.56-1.69]). Similarly, the adjusted odds of a below mean integration into employment were 1.63 higher among TRD patients compared with non-TRD patients (95% CI [1.56-1.70]). CONCLUSION: Patients with TRD have higher levels of sickness absence and lower levels of reintegration into the labor market after meeting the criteria for TRD compared with patients without TRD.

Pregnancy and postpartum psychiatric episodes in fathers: A population-based study on treatment incidence and prevalence.

BACKGROUND: For women, the perinatal period confers an increased risk of severe psychiatric disorders, but similar evidence for fathers is lacking. We examined rates of first-time and recurrent psychiatric disorders in men before and after becoming fathers. METHODS: A descriptive prospective study design was applied using information from the Danish National registers. Perinatal psychiatric episodes were assessed as incidence of first-time and prevalence (including recurrence) of recorded in- or outpatient admissions for any mental disorder and redeemed prescriptions for psychotropic medication in fathers to children born from January 1, 1998 until December 31, 2015. RESULTS: We identified 929,415 births and 543,555 unique fathers. Incidence and prevalence proportions for paternal psychiatric in- and outpatient episodes showed an increasing trend over the perinatal period and were marginally higher postpartum compared to pregnancy; e.g., median incidence proportion for inpatient treatment during pregnancy was 0.07 (95% CI: 0.04; 0.07) and 0.10 (95% CI: 0.08; 0.11) postpartum per 1000 births. No difference between the periods was found for incidence of prescriptions for psychotropic medication. Psychiatric disorders in expecting and new fathers were mainly treated in primary care with cumulative incidence of prescriptions for psychotropic medication of 14.56 per 1000 births during the first year of fatherhood. LIMITATIONS: We only capture fathers who actively sought and received treatment, and we consequently underestimate milder psychiatric episodes in expecting and new fathers. CONCLUSION: Becoming a father did not appear to trigger a substantially increased risk of severe psychiatric disorders, as it has been observed for new mothers.

Bidirectional associations between treatment-resistant depression and general medical conditions.

Depression is associated with general medical conditions (GMCs), but it is not known if treatment-resistant depression (TRD) affects GMC risk and vice versa. We estimated bidirectional associations between TRD and GMCs (prior and subsequent). All individuals aged 18-69 years, born and living in Denmark, with a first-time prescription for an antidepressant between 2005 and 2012 were identified in the Danish Prescription Registry (N = 154,513). TRD was defined as at least two shifts in treatment regimes. For prior GMCs, we estimated odds ratios (ORs) using conditional logistic regression comparing TRD patients with matched non-TRD controls adjusted for other GMCs and number of other GMCs. For subsequent GMCs, we used Cox regression to calculate hazard ratios (HRs) in TRD vs. non-TRD patients adjusted for age at first prescription, calendar time, other GMCs and number of other GMCs. Patients with TRD had higher prevalence of prior GMCs related to the immune or neurological systems; musculoskeletal disorders (women aOR: 1.35, 95% CI: 1.26-1.46, men aOR: 1.30, 95% CI: 1.19-1.42) and migraine (women aOR: 1.22, 95% CI: 1.09-1.36, men aOR: 1.25, 95% CI: 1.00-1.56). Subsequent GMCs were related to a broader spectrum; cardiovascular (women aHR: 1.43, 95% CI: 1.32-1.54, men aHR: 1.31, 95% CI: 1.19-1.43), endocrine (women aHR: 1.52, 95% CI: 1.37-1.67, men aHR: 1.24, 95% CI: 1.07-1.44), and neurological disorders (women aHR: 1.24, 95% CI: 1.13-1.35, men aHR: 1.19, 95% CI: 1.07-1.34). Our study presents a broad overview of comorbid medical conditions in patients with TRD and further studies are needed to explore the associations in detail.

Cause-specific life years lost in individuals with treatment-resistant depression: A Danish nationwide register-based cohort study.

BACKGROUND: Depression is associated with excess mortality, but it is not known how treatment-resistance influences life expectancy. We estimated cause-specific excess mortality and Life Years Lost (LYL) in patients with treatment-resistant depression (TRD). METHODS: The population included all individuals born and living in Denmark who redeemed their first prescription for an antidepressant at age 18-69 years between 2005 and 2012, identified in the Danish National Prescription Registry. TRD was defined as at least two additional and different antidepressant trials within two years. Mortality rate ratios (MRRs) were estimated with Cox regression adjusted for age at first prescription, calendar year and comorbidity. Differences in life expectancy were estimated by the Life Years Lost (LYL) method. RESULTS: The cohort included 154,513 first-time pharmacologically treated patients with depression, of whom 8,294 (5.4%) were identified as having TRD. Patients were followed for 1,032,245 person-years during which 9,795 deaths occurred. Men and women with TRD had significantly higher mortality than non-TRD (aMRR: 1.34, 95% CI 1.18-1.52 and aMRR: 1.39, 95% CI 1.19-1.63, respectively). Life expectancy for men and women with TRD was 1.21 (95% CI 0.36-2.44) and 1.24 (95% CI 0.35-2.34) years shorter than in all patients with depression. Suicide accounted for the majority of excess LYL, with 1.10 (95% CI 0.46-1.61) years in men and 0.82 (95% CI 0.44-1.27) years in women with TRD. LIMITATIONS: Using redeemed prescriptions to define TRD may increase the risk of misclassification. CONCLUSIONS: Patients not responding adequately to several treatment trials are at increased risk for premature death, particularly suicide.

Depression-related distortions in maternal reports of child behaviour problems.

Associations between maternal depression and child behaviour problems may be biased due to depression-related distortions in the maternal reports. In this study, we compared the agreement between maternal, teacher and child ratings of hyperactivity/inattention (H/I), conduct (CD) and emotional (EM) problems measured with the Strengths and Difficulties Questionnaire in a population with depressed and non-depressed mothers. The sample of 12,961 11-year-old children was drawn from the Danish National Birth Cohort. We also examined the association between maternal depression before and during the child's life and child H/I, CD and EM problems when reported by the different informants. Agreement between the informants was assessed with the Bland-Altman limits of agreement (LOA) and associations were analyzed using multiple linear regression models. We found large discrepancies between maternal and teacher ratings of child behavioural problems measured with the SDQ and less discrepancy between maternal and child self-ratings. Better agreement between informants was found in the population of depressed mothers compared to non-depressed mothers for H/I and CD problems, and not for EM symptoms. The LOA for all three subscales were wide in both populations, with the largest intervals ranging from - 6 (Lower LOA) to 3 (Upper LOA) for H/I. Statistically significant associations were found between maternal depression, and child H/I and CD problems when reported by the mother but not the teacher and only by the child, when maternal depression had been present during the child's life. Our findings emphasize the importance of considering each informants' ratings when obtaining ratings from multiple sources.

Social selection in cohort studies and later representation of childhood psychiatric diagnoses: The Danish National Birth Cohort.

Aim: This study aimed to estimate the relative representation of childhood psychiatric diagnoses and use of psychotropic medication in the Danish National Birth Cohort (DNBC) compared to the general population. Methods: The general population was identified as all childbirths in Denmark during 1998-2002 (N=344,160). Linking the DNBC (N=91,442) and the general population to the Danish national health registries, all children were followed until they received an ICD-10 psychiatric diagnosis, had a prescription of psychotropic medication or to the end of follow-up in 2013. The prevalence ratios (PRs) with corresponding 95% confidence intervals (CI) were estimated for each psychiatric diagnosis and by sex. Age at first diagnosis presented as means were compared using the one-sample t-test. Results: In the DNBC, the selected childhood psychiatric diagnoses were underrepresented by 3% (PR=0.97, 95% CI 0.94-0.99), ranging from a 20% underrepresentation for schizophrenia (PR=0.80, 95% CI 0.59-1.09) to a 6% over-representation for anxiety disorder or obsessive-compulsive disorder (PR=1.06, 95% CI 0.97-1.17). The majority of the specific diagnoses were modestly underrepresented in the DNBC compared to the general population, while use of psychotropic medication had similar representation. Girls were generally more underrepresented than boys. Depression was on average diagnosed 0.4 years earlier in the DNBC than in the general population (p=0.023). Conclusions: These findings suggest that the social selection may influence the prevalence of diagnosed childhood psychiatric disorders in the DNBC.

Incidence Rates and Cumulative Incidences of the Full Spectrum of Diagnosed Mental Disorders in Childhood and Adolescence.

Importance: Knowledge about the epidemiology of mental disorders in children and adolescents is essential for research and planning of health services. Surveys can provide prevalence rates, whereas population-based registers are instrumental to obtain precise estimates of incidence rates and risks. Objective: To estimate age- and sex-specific incidence rates and risks of being diagnosed with any mental disorder during childhood and adolescence. Design: This cohort study included all individuals born in Denmark from January 1, 1995, through December 31, 2016 (1.3 million), and followed up from birth until December 31, 2016, or the date of death, emigration, disappearance, or diagnosis of 1 of the mental disorders examined (14.4 million person-years of follow-up). Data were analyzed from September 14, 2018, through June 11, 2019. Exposures: Age and sex. Main Outcomes and Measures: Incidence rates and cumulative incidences of all mental disorders according to the ICD-10 Classification of Mental and Behavioral Disorders: Diagnostic Criteria for Research, diagnosed before 18 years of age during the study period. Results: A total of 99 926 individuals (15.01%; 95% CI, 14.98%-15.17%), including 41 350 girls (14.63%; 95% CI, 14.48%-14.77%) and 58 576 boys (15.51%; 95% CI, 15.18%-15.84%), were diagnosed with a mental disorder before 18 years of age. Anxiety disorder was the most common diagnosis in girls (7.85%; 95% CI, 7.74%-7.97%); attention-deficit/hyperactivity disorder (ADHD) was the most common in boys (5.90%; 95% CI, 5.76%-6.03%). Girls had a higher risk than boys of schizophrenia (0.76% [95% CI, 0.72%-0.80%] vs 0.48% [95% CI, 0.39%-0.59%]), obsessive-compulsive disorder (0.96% [95% CI, 0.92%-1.00%] vs 0.63% [95% CI, 0.56%-0.72%]), and mood disorders (2.54% [95% CI, 2.47%-2.61%] vs 1.10% [95% CI, 0.84%-1.21%]). Incidence peaked earlier in boys than girls in ADHD (8 vs 17 years of age), intellectual disability (5 vs 14 years of age), and other developmental disorders (5 vs 16 years of age). The overall risk of being diagnosed with a mental disorder before 6 years of age was 2.13% (95% CI, 2.11%-2.16%) and was higher in boys (2.78% [95% CI, 2.44%-3.15%]) than in girls (1.45% [95% CI, 1.42%-1.49%]). Conclusions and Relevance: This nationwide population-based cohort study provides a first comprehensive assessment of the incidence and risks of mental disorders in childhood and adolescence. By 18 years of age, 15.01% of children and adolescents in this study were diagnosed with a mental disorder. The incidence of several neurodevelopmental disorders peaked in late adolescence in girls, suggesting possible delayed detection. The distinct signatures of the different mental disorders with respect to sex and age may have important implications for service planning and etiological research.

Family dissolution and children's social well-being at school: a historic cohort study.

BACKGROUND: Family dissolution has become more common and one third of the child population in most Western countries now experience family dissolution. Studies show that children from dissolved families have lower levels of social well-being than children from intact families, but only few studies have examined the impact on social well-being specifically in the school setting. We investigated the association between family dissolution and children's social well-being at school, including the possible influence of the child's age at the time of the family dissolution. METHODS: We defined a historic cohort study of 219,226 children and adolescents aged 9-16 years and combined demographic registry data of family structure with questionnaire data on social well-being based on the Danish National Well-being Questionnaire completed in 2015. The definition of social well-being was constructed on the children's perception of sense of belonging in the school setting, in the class and the school community, as well as perceptions on safety, loneliness and bullying. We examined low social well-being according to family dissolution and used multiple logistic regression analyses to adjust for parental educational level, ethnicity and siblings and further stratified for gender and age. RESULTS: A total of 5% of the children had a low social well-being at school. Among the 31% who lived in dissolved families, we found more children with a low level of social well-being at school (adjusted OR 1.41, 95% CI 1.36;1.47) than those in intact families; especially among those who at the time of family dissolution were in the preschool age (1.55, 95% CI 1.47;1.64). CONCLUSION: Children from dissolved families had higher odds for low social well-being at school compared with children from intact families, especially those who experienced family dissolution in the preschool age. The school may be an important setting for identifying and providing help and support in children experiencing family dissolution.

The impact of childhood bullying on the daily lives of Nordic children and young adolescents.

AIM: Childhood bullying may negatively affect the mental health in children and adolescents, but few studies have explored this potential link. We aimed to investigate the association between childhood bullying and the impact of poor mental health on the daily life in a population of Nordic children and adolescents aged 5-16 years. METHODS: This cross-sectional study was based on data from the Nordic survey on Children's Health and Wellbeing (NordChild) from 2011. The study population included 4966 children from Denmark, Finland, Iceland, Norway and Sweden. Mental health was measured by a parent-reported version of the Strength and Difficulties Questionnaire. We conducted multiple logistic regression analyses to estimate the odds ratios of poor mental health in bullied compared to non-bullied children and adolescents while adjusting for sex, age, body mass index and parental socioeconomic status. RESULTS: Bullied children and adolescents were four times more likely than their non-bullied peers to have mental health problems with negative impact on their daily life at home, in their relations to friends, learning in school or leisure activities (adjusted odds ratio: 4.32; 95% CI: 3.54-5.26). CONCLUSION: This study found negative impact on the mental health in bullied children and adolescents, which affected several arenas of daily life.

The predictive validity of the Strengths and Difficulties Questionnaire for child attention-deficit/hyperactivity disorder.

We need accurate screening measures for attention-deficit/hyperactivity disorder (ADHD) to ensure that children with the disorder are referred for assessment without raising concern for children with normal behaviour. The Strengths and Difficulties Questionnaire (SDQ) provides hyperactivity-inattention (HI), conduct, emotional and peer problem subscales and impact scores that may be used for screening. The aim of the study was to investigate the predictive validity of the Danish version of the parent SDQ HI subscale at the child age of 7 years for subsequent clinically diagnosed ADHD (age 8-15 years). Participants were part of the Danish National Birth Cohort (N = 51,096), and children with ADHD were identified through the Danish National Health registries (n = 943). Receiver operating characteristic analysis showed that the screening accuracy for the HI scores was good (area under the curve = .84). With Cox multivariate regression analysis, we found that SDQ HI subscale scores ≥ 7 with impact gave a nearly 14-fold [hazard ratio (HR) = 13.59] increased risk for ADHD, while conduct and emotional problems indicated low risk (HRs of 1.62 and 1.67, respectively). For the HI subscale to be a sensitive measure for ADHD, a low cutoff (4) was needed, but gave many false screening positives (PPV = .02). Although the diagnostic accuracy of the parent version of the SDQ HI subscale for predicting ADHD was good, our results question the feasibility of screening the general child population for ADHD with only the parent SDQ HI subscale.

Characteristics of undiagnosed children with parent-reported ADHD behaviour.

There is an ongoing public debate on the diagnosis of attention deficit hyperactivity disorder (ADHD) in which critics have claimed that the disorder is over-diagnosed, while the potential under-diagnosis of children with ADHD has received little attention. In this study we estimate the number of children with parent-reported ADHD behaviour at age 7 and absence of recorded ADHD diagnosis through adolescence, and investigate whether socio-demographic characteristics of this group differed from the children diagnosed with ADHD during follow-up. Our study was based on data from the Danish National Birth Cohort, where parents of 51,527 children completed questionnaires, including the Strength and Difficulties Questionnaire (SDQ). ADHD diagnosis was identified through Danish registers and parent-reported ADHD behaviour by the specific SDQ subscale. Socio-demographic predictors of positive parent-reported SDQ ADHD behaviour and absence of recorded ADHD diagnosis in their children were examined using logistic regression analyses. Children with parent-reported ADHD behaviour and no diagnosis (1.3%) were more likely to be girls (OR 1.83; 95% CI 1.45; 2.29), more likely to have mothers with a low socioeconomic status (OR high vs. low 1.49; 95% CI 1.10; 2.02), and to live in certain regions of the country (OR: Capital vs. Southern: 2.04; 95% CI 1.51; 2.73) than children with an ADHD diagnosis. The children showed markedly impairments on all the SDQ subscales. The results demonstrate a considerable number of children with ADHD symptoms who potentially go undetected and underline the influence of socio-demographic factors in the pathway to a diagnosis of ADHD.