An association between psychiatric disorders in childhood and the later development of major depressive disorders (MDD) has been suggested. However, no prospective population-based cohort study has been able to directly compare the risks of MDD following a broad spectrum of child and adolescent psychiatric disorders.

To use a large, register-based cohort to establish whether or not psychiatric disorders in childhood lead to a higher risk of later MDD and, if so, which disorders are associated with the highest risks.

To estimate and compare the risk of later MDD in children diagnosed with one of ten psychiatric disorders

Using Danish population-based registers all persons born in Denmark from 1990 through 2000 were identified and followed from their 5^th birthday through 2012. Cumulative incidences and incidence rate ratios of MDD following each of ten exposure disorders were calculated

We followed 960,026 persons, contributing 8,778,331 person-years. Among these 7,787 were diagnosed with MDD (incidence=1.7/1000 pyrs).

Diagnosis of any psychiatric disorder led to an absolute risk of MDD within eight years of 1.6% in males and 4.98% in females with early onset (ages 0-14) and 7.02% in males and 15.98% in females with late onset (ages 14-18).

For all groups, anxiety and eating disorders were associated with the highest risks of MDD.

Most disorders were associated with a significantly increased risk of later MDD and children with anxiety and eating disorders carry the greater risk. Future research should focus on common pathways between depression and other psychiatric disorders.

To examine 5 years trajectories of secondary-treated late-life major depressive disorder (MDD), and evaluate whether pre-existing cerebrovascular disease and related risk factors are associated with more severe trajectories of late-life MDD.

Data were obtained from Danish registers. The sample included 11,184 adults ≥ 60 at index MDD diagnosis. Trajectories of in or outpatient contact at psychiatric hospitals for MDD over the 5 years period following index MDD diagnosis were modeled using latent class growth analysis. Risk factors included cerebrovascular disease, cardiovascular disease, hypertension, diabetes, and vascular dementia defined based on hospital diagnoses and prescription medications, demographic characteristics and characteristics of the index MDD diagnosis.

The final model included classes with consistently low (66%), high decreasing (19%), consistently high (9%) and moderate fluctuating (6%) probabilities of contact at a psychiatric hospital for MDD during the 5 year period following the index MDD diagnosis (Fig. 1). Older age, greater severity, inpatient treatment and > 12 antidepressant prescriptions within 5 years of the index MDD diagnosis predicted membership in more severe trajectory classes. Cerebrovascular disease and related risk factors were not associated with trajectory class membership.

A substantial proportion (34%) of individuals diagnosed with MDD in late-life require specialized psychiatric treatment for extended periods of time. We found no evidence that cerebrovascular disease or related risk factors predicted course trajectories in secondary-treated late-life MDD.

The authors have not supplied their declaration of competing interest.

The postpartum period is well-known risk period for the first onset of autoimmune thyroid disorders (AITDs) as well as first onset of psychiatric disorders. These two disorders are some of the most prevalent medical conditions postpartum, often misdiagnosed and disabling if left untreated. Our study was designed to explore the possible bidirectional association between AITDs and psychiatric disorders during the postpartum period.

A population-based cohort study through linkage of Danish national registers, which comprised 312 779 women who gave birth to their first child during 1997–2010. We conducted Poisson regression analysis to estimate the incidence rate ratio (IRR) of psychiatric disorders among women with first-onset AITDs, the IRR of AITDs among women with first-onset psychiatric disorders as well as the overlap between these disorders using a comorbidity index.

Women with first-onset AITDs postpartum were more likely to have first-onset psychiatric disorders than women who did not have postpartum AITDs (IRR = 1.88, 95% confidence interval (CI): 1.25–2.81). Women with first-onset postpartum psychiatric disorders had a higher risk of AITDs than women with no psychiatric disorders (IRR = 2.16, 95% CI: 1.45–3.20). The comorbidity index 2 years after delivery was 2.26 (95% CI: 1.61–2.90), indicating a comorbidity between first-onset AITDs and psychiatric disorders.

First-onset AITDs and psychiatric disorders co-occur in the postpartum period, which has relevance to further studies on the etiologies of these disorders and why childbirth in particular triggers the onset.

Childbirth is a potent trigger for the onset of psychiatric illness in women including postpartum depression (PPD) and postpartum psychosis (PP). Medical complications occurring during pregnancy and/or childbirth have been linked to postpartum psychiatric illness and sociodemographic factors. We evaluated if pregnancy and obstetrical predictors have similar effects on different types of postpartum psychiatric disorders.

A population-based cohort study using Danish registers was conducted in 392 458 primiparous women with a singleton delivery between 1995 and 2012 and no previous psychiatric history. The main outcome was first-onset postpartum psychiatric episodes. Incidence rate ratios (IRRs) were calculated for any psychiatric contact in four quarters for the first year postpartum.

PPD and postpartum acute stress reactions were associated with pregnancy and obstetrical complications. For PPD, hyperemesis gravidarum [IRR 2.69, 95% confidence interval (CI) 1.93–3.73], gestational hypertension (IRR 1.84, 95% CI 1.33–2.55), pre-eclampsia (IRR 1.45, 95% CI 1.14–1.84) and Cesarean section (C-section) (IRR 1.32, 95% CI 1.13–1.53) were associated with increased risk. For postpartum acute stress, hyperemesis gravidarum (IRR 1.93, 95% CI 1.38–2.71), preterm birth (IRR 1.51, 95% CI 1.30–1.75), gestational diabetes (IRR 1.42, 95% CI 1.03–1.97) and C-section (IRR 1.36, 95% CI 1.20–1.55) were associated with increased risk. In contrast, risk of PP was not associated with pregnancy or obstetrical complications.

Pregnancy and obstetrical complications can increase the risk for PPD and acute stress reactions but not PP. Identification of postpartum women requiring secondary care is needed to develop targeted approaches for screening and treatment. Future work should focus on understanding the contributions of psychological stressors and underlying biology on the development of postpartum psychiatric illness.

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

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

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

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

Recent evidence suggests that postpartum psychiatric episodes may share similar etiological mechanisms with immune-related disorders. Pre-eclampsia is one of the most prevalent immune-related disorders of pregnancy. Multiple clinical features are shared between pre-eclampsia and postpartum psychiatric disorders, most prominently a strong link to first pregnancies. Therefore, we aimed to study if pre-eclampsia is a risk factor for first-onset postpartum psychiatric episodes.

We conducted a cohort study using the Danish population registry, with a total of 400 717 primiparous women with a singleton delivery between 1995 and 2011. First-lifetime childbirth was the main exposure variable and the outcome of interest was first-onset postpartum psychiatric episodes. The main outcome measures were monthly incidence rate ratios (IRRs), with the period 11–12 months after birth as the reference category. Adjustments were made for age, calendar period, reproductive history, and perinatal maternal health including somatic and obstetric co-morbidity.

Primiparous women were at particularly high risk of first-onset psychiatric episodes during the first month postpartum [IRR 2.93, 95% confidence interval (CI) 2.53–3.40] and pre-eclampsia added to that risk (IRR 4.21, 95% CI 2.89–6.13). Having both pre-eclampsia and a somatic co-morbidity resulted in the highest risk of psychiatric episodes during the 3-month period after childbirth (IRR 4.81, 95% CI 2.72–8.50).

We confirmed an association between pre-eclampsia and postpartum psychiatric episodes. The possible explanations for this association, which are not mutually exclusive, include the psychological impact of a serious medical condition such as pre-eclampsia and the neurobiological impact of pre-eclampsia-related vascular pathology and inflammation.

Depression is known to run in families, but the effects of parental history of other psychiatric diagnoses on depression rates are less well studied. Few studies have examined the impact of parental psychopathology on depression rates in older age groups.

We established a population-based cohort including all individuals born in Denmark after 1954 and alive on their 10th birthday (N = 29 76 264). Exposure variables were maternal and paternal history of schizophrenia, bipolar disorder, depression, anxiety or ‘other’ psychiatric diagnoses. Incidence rate ratios (IRRs) were estimated using Poisson regressions.

Parental history of any psychiatric diagnosis increased incidence rates of outpatient (maternal: IRR 1.88, p < 0.0001; paternal: IRR 1.68, p < 0.0001) and inpatient (maternal: IRR 1.99, p < 0.0001; paternal: IRR 1.83, p < 0.0001) depression relative to no parental history. IRRs for parental history of non-affective disorders remained relatively stable across age groups, while IRRs for parental affective disorders (unipolar or bipolar) decreased with age from 2.29–3.96 in the youngest age group to 1.53–1.90 in the oldest group. IRR estimates for all parental diagnoses were similar among individuals aged ⩾41 years (IRR range 1.51–1.90).

Parental history of any psychiatric diagnosis is associated with increased incidence rates of unipolar depression. In younger age groups, parental history of affective diagnoses is more strongly associated with rates of unipolar depression than non-affective diagnoses; however, this distinction disappears after age 40, suggesting that parental psychopathology in general, rather than any one disorder, confers risk for depression in middle life.