Family aggregation of mental disorders in the nationwide Danish three generation study

Mindful Parenting Group Intervention for Parents of Children with Anxiety Disorders

Parenting behaviour and rearing style contribute to the intergenerational relationship between parental and child anxiety. Current psychological interventions for child anxiety typically do not adequately address parental mental health, parenting behaviours or the parent-child relationship. The current pilot study examines the effectiveness of a mindful parenting intervention (MPI) for parents of young children with clinical anxiety. It was hypothesised that the intervention would be associated with improvements in parental stress, mental health, and mindfulness, and a reduction in child clinical anxiety symptoms. Twenty-one parents of children aged 3-7 years diagnosed with anxiety disorders participated in an 8-week group MPI program that aimed to increase their intentional moment to moment awareness of the parent-child relationship. Parental (anxiety, depression, hostility, stress, burden, mindfulness, mindful parenting) and child (anxiety diagnoses, anxiety severity, comorbidities) outcomes were assessed at pre- and post-intervention, and at 3-month follow-up. Parents reported a significant increase in mindful parenting and a significant reduction in parent-child dysfunctional interaction, but no change in mental health symptoms. There was a significant reduction in parent-rated child anxiety symptoms, severity of child anxiety diagnosis and number of comorbid diagnoses at post and 3-month follow-up. Limitations include a lack of waitlist control, small sample size, and participants were largely mothers, from intact families and highly educated. There was attrition of 43% and outcomes were predominantly self-report. MPIs offer a novel and potentially effective method of increasing mindful parenting, decreasing dysfunctional parent-child interactions, reducing parenting stress and might also be an effective early intervention for indirectly decreasing young children's clinical anxiety symptoms. Larger-scale controlled trials of MPIs are needed.

Parental psychopathology and offspring anxiety disorders in childhood and adolescence: A Finnish nationwide register study

BACKGROUND

Research suggests an association between parental psychiatric disorders and offspring anxiety disorders, yet comprehensive studies are limited. This study aims to investigate the associations between various parental psychiatric disorders and anxiety disorders in their offspring.

METHOD

Using Finnish register data, this nested case-control study analyzed 867,175 singleton live births from 1992 to 2006, identifying 21,671 cases of anxiety disorders diagnosed between 1998 and 2016. Matched with four controls each (n = 72,414) based on age and biological sex, the study adjusted for demographic and prenatal factors using conditional logistic regression models to calculate odds ratios (aORs).

RESULTS

There was a significant association between parental psychiatric disorders and increased risk of anxiety disorders in offspring. The risk was notably higher when both parents had psychiatric disorders (aOR = 5.04; 95 % CI, 4.70-5.39; p < .001). Maternal psychiatric disorders were strongly associated with offspring anxiety than paternal disorders (aOR 1.52; 95 % CI 1.43-1.61; p < .001). This association was consistent regardless of timing of parental diagnosis. Significant associations were observed between any parental psychiatric disorder and increased risks in offspring for specific phobia, social phobia, generalized anxiety disorder, separation anxiety, and panic disorder. Maternal psychiatric disorders showed elevated risk for panic disorder and social phobia among girls and separation anxiety and generalized anxiety among boys.

CONCLUSION

The findings emphasize the significant impact of parental psychiatric health on offspring anxiety disorders, highlighting the influence of genetic and environmental factors. Addressing parental mental health is crucial in preventing childhood anxiety disorders.

Incidence Trajectories of Psychiatric Disorders After Assault, Injury, and Bereavement

Importance

Traumatic events have been associated with elevated risks of psychiatric disorders, while the contributions of familial factors to these associations remain less clear.

Objective

To determine the contribution of familial factors to long-term incidence trajectories of psychiatric disorders following potentially traumatic events.

Design, Setting, and Participants

This cohort study evaluated 3 separate cohorts of individuals residing in Sweden who were free of previous diagnosed psychiatric disorders when first exposed to assault (n = 49 957), injury (n = 555 314), or bereavement (n = 321 263) from January 1987 to December 2013, together with their unexposed full siblings, and 10 age-, sex-, and birthplace-matched unexposed individuals (per exposed individual). Cohorts were created from the Swedish Total Population Register linked to health and population registers. Data were analyzed from March 2022 to April 2023.

Exposures

Potentially traumatic events, including various types of assault, injuries, and bereavement (death of a child or of a spouse or partner), were ascertained from the Swedish national registers.

Main Outcomes and Measures

Incident psychiatric disorders were ascertained from the Swedish Patient Register. Flexible parametric and Cox models were used to estimate associations of potentially traumatic events with incident psychiatric disorders after multivariable adjustment.

Results

The median (IQR) age at exposure to assault, injury, and bereavement was 22 (18-31), 19 (8-40), and 60 (51-68) years, respectively. During a median (IQR) follow-up of 4.9 (2.2-8.2), 9.1 (4.1-15.6), and 8.1 (3.4-14.8) years, the incidence rates of any psychiatric disorder were 38.1, 13.9, and 9.0 per 1000 person-years for the exposed groups of the 3 cohorts, respectively. Elevated risk of any psychiatric disorder was observed during the first year after exposure to any assault (hazard ratio [HR], 4.55; 95% CI, 4.34-4.77), injury (HR, 3.31; 95% CI,3.23-3.38), or bereavement (HR, 2.81; 95% CI, 2.72-2.91) and thereafter (assault HR, 2.50; 95% CI, 2.43-2.56; injury HR, 1.69; 95% CI, 1.68-1.70; bereavement HR, 1.42; 95% CI, 1.40-1.44). Comparable associations were obtained in sibling comparison (first year: assault HR, 3.70; 95% CI, 3.37-4.05; injury HR, 2.98; 95% CI, 2.85-3.12; bereavement HR, 2.72; 95% CI, 2.54-2.91; thereafter: assault HR, 1.93; 95% CI, 1.84-2.02; injury HR, 1.51; 95% CI, 1.48-1.53; bereavement HR, 1.35; 95% CI, 1.31-1.38). The risk elevation varied somewhat by type of traumatic events and psychiatric disorders, with the greatest HR noted for posttraumatic stress disorder after sexual assault (sibling comparison HR, 4.52; 95% CI, 3.56-5.73 during entire follow-up period).

Conclusions and Relevance

In this study, the long-term risk elevation of psychiatric disorders after potentially traumatic events was largely independent of familial factors. The risk elevation observed immediately after these events motivates early clinical surveillance and mental health services for these vulnerable populations.

Selective mutism and the risk of mental and neurodevelopmental disorders among siblings

The siblings of children with mental disorders are more likely to experience mental health issues themselves, but there has been a lack of sibling studies on selective mutism (SM). The aim of this population-based study was to use national registers to examine associations between children with SM and diagnoses of various mental disorder in their siblings. All singleton children born in Finland from 1987 to 2009, and diagnosed with SM from 1998 to 2012, were identified from national health registers and matched with four controls by age and sex. Their biological siblings and parents were identified using national registries and the diagnostic information on the siblings of the subjects and controls was obtained. The final analyses comprised 658 children with SM and their 1661 siblings and 2092 controls with 4120 siblings. The analyses were conducted using generalized estimating equations. Mental disorders were more common among the siblings of the children with SM than among the siblings of the controls. The strongest associations were observed for childhood emotional disorders and autism spectrum disorders after the data were adjusted for covariates and comorbid diagnoses among SM subjects. The final model showed associations between SM and a wide range of disorders in siblings, with strongest associations with disorders that usually have their onset during childhood. Our finding showed that SM clustered with other mental disorders in siblings and this requires further research, especially the association between SM and autism spectrum disorders. Strong associations with childhood onset disorders may indicate shared etiologies.

Weighing psychosocial factors in relatives for the risk of psychopathology: a study of patients with depressive and anxiety disorders and their siblings

PURPOSE

Siblings of probands with depressive and anxiety disorders are at increased risk for psychopathology, but little is known about how risk factors operate within families to increase psychopathology for siblings. We examined the additional impact of psychosocial risk factors in probands-on top of or in combination with those in siblings-on depressive/anxious psychopathology in siblings.

METHODS

The sample included 636 participants (Mage = 49.7; 62.4% female) from 256 families, each including a proband with lifetime depressive and/or anxiety disorders and their sibling(s) (N = 380 proband-sibling pairs). Sixteen psychosocial risk factors were tested. In siblings, depressive and anxiety disorders were determined with standardized psychiatric interviews; symptom severity was measured using self-report questionnaires. Analyses were performed with mixed-effects models accounting for familial structure.

RESULTS

In siblings, various psychosocial risk factors (female gender, low income, childhood trauma, poor parental bonding, being single, smoking, hazardous alcohol use) were associated with higher symptomatology and likelihood of disorder. The presence of the same risk factor in probands was independently associated (low income, being single) with higher symptomatology in siblings or moderated (low education, childhood trauma, hazardous alcohol use)-by reducing its strength-the association between the risk factor and symptomatology in siblings. There was no additional impact of risk factors in probands on likelihood of disorder in siblings.

CONCLUSION

Our findings demonstrate the importance of weighing psychosocial risk factors within a family context, as it may provide relevant information on the risk of affective psychopathology for individuals.

Familial resemblance in mental health symptoms, social and cognitive vulnerability, and personality: A study of patients with depressive and anxiety disorders and their siblings

BACKGROUND

Investigating siblings of probands with affective disorders enables the identification of psychopathology-related risk features. Leveraging data from an older adult sample, as compared to most previous sibling studies, enabled us to study more definitive clinical profiling across the lifespan. We examined prevalence of depressive/anxiety disorders in siblings, proband-sibling resemblance in psychopathology-related features, and whether unaffected siblings showed higher levels of these features than healthy controls.

METHODS

The sample (N=929; M_age=50.6) consisted of 256 probands with lifetime depressive and/or anxiety disorders, their 380 siblings, and 293 healthy controls without affected relatives. Fifteen psychopathology-related features were investigated across four domains: mental health symptoms, social vulnerabilities, cognitive vulnerabilities, and personality.

RESULTS

Lifetime disorders were present in 50.3% of siblings. Prevalence was 2-3 times higher than Dutch population frequencies. We found small to medium probandsibling resemblance across psychopathology-related features (ρ=0.10-0.32). Unaffected siblings reported poorer interpersonal functioning and more negative life events, childhood trauma, and rumination than healthy controls.

LIMITATIONS

Due to the cross-sectional study design, the directionality of effects cannot be determined. No inferences can be made about potential differences in familial resemblance in psychopathology-related features between high- and low-risk families.

CONCLUSIONS

Siblings of probands with affective disorders are at higher risk for depressive/anxiety disorders. Even when unaffected, still show higher psychosocial vulnerability than healthy controls. Nevertheless, the only modest proband-sibling resemblance across psychopathology-related features suggests that individual mechanisms differentiate clinical trajectories across the lifespan. Identification of these mechanisms is crucial to improve resilience in subjects with familial risk.

The impact of parental psychopathology and sociodemographic factors in selective mutism - a nationwide population-based study

BACKGROUND

Selective mutism (SM) is nowadays considered a relatively rare anxiety disorder characterized by children failing to speak in certain situations. Research on risk factors for SM are limited in comparison to other psychiatric disorders. The aim of this study was to examine several potential risk factors for SM in a large nationwide cohort, namely parental psychopathology, parental age, maternal SES, urbanicity, maternal marital status and parental immigration status.

METHODS

This nested case-control study comprised 860 cases with SM, identified from the Finnish Hospital Discharge Register and 3250 controls matched for sex and age from the Finnish Central Population Register. Conditional logistic regression was used to examine the association between the risk factors and SM.

RESULTS

If both parents had any psychiatric disorder, this almost tripled their odds of having a child with SM (OR 2.8, 95% CI 2.0-4.0). There were increased rates of all types of psychiatric disorders in the parents of the children with SM, with a wider range of diagnoses among the mothers than fathers. Fathers over 35 years (OR 1.4, 95% CI 1.1-1.8) were significantly more likely to have children with SM. Offspring of a single mother had a 2-fold (OR = 2.0, 95% CI 1.4-3.0) increased odds of SM than mothers who were married or in a relationship.

CONCLUSIONS

Several parental psychiatric disorders were associated with offspring SM. This points towards a shared aetiology of psychiatric disorders. Findings on paternal age and single motherhood help to improve our understanding of risk factors for SM.

Mortality by diseases and medical conditions in the offspring of parents with severe mental illness

PURPOSE

The lifespan of people with severe mental illness (SMI) is shorter compared to the general population. There might be common familial pathway leading to a high co-occurrence of somatic disorders and SMI. To study this we explored the long-term mortality for natural causes in the offspring of people with SMI.

METHODS

Participants were members of the Northern Finland Birth Cohort 1966 (NFBC1966; N = 11,325). The data on cause of deaths of the members were obtained from the Population Register Center until year 2015. The data on hospital-treated psychiatric disorders of parents were obtained from nationwide Care Register for Health Care. Cumulative incidences by age were calculated in the NFBC1966 members having a parent with SMI and those who did not have. We were able to take into account multiple confounders.

RESULTS

Of the total sample of 11,325 offspring, 853 (7.4%) died during the follow-up period, 74 (8.7%) from the study cohort and 779 (91.3%) from the comparison group. These numbers included 160 stillborn children. There were 557 cases of deaths from diseases and medical conditions and 296 deaths from external causes. The adjusted risk ratio for offspring of mothers with SMI was 1.08 (0.72-1.64), and for offspring of fathers with SMI 0.58 (0.36-0.93).

CONCLUSIONS

This was the first long-term follow-up study (up to age 49) of all-cause mortality in offspring of parents with SMI. Our findings were contrary to expectations. Offspring of parents with SMI had no increased risk for dying. In fact, the risk for dying in the group of offspring of fathers with SMI was lower than in the comparison group. This study does not support the assumption of common familial pathway leading to a high co-occurrence of somatic disorders and SMI.

Shared atypical default mode and salience network functional connectivity between autism and schizophrenia

Schizophrenia and autism spectrum disorder (ASD) are two prevalent neurodevelopmental disorders sharing some similar genetic basis and clinical features. The extent to which they share common neural substrates remains unclear. Resting-state fMRI data were collected from 35 drug-naïve adolescent participants with first-episode schizophrenia (15.6 ± 1.8 years old) and 31 healthy controls (15.4 ± 1.6 years old). Data from 22 participants with ASD (13.1 ± 3.1 years old) and 21 healthy controls (12.9 ± 2.9 years old) were downloaded from the Autism Brain Imaging Data Exchange. Resting-state functional networks were constructed using predefined regions of interest. Multivariate pattern analysis combined with multi-task regression feature selection methods were conducted in two datasets separately. Classification between individuals with disorders and controls was achieved with high accuracy (schizophrenia dataset: accuracy = 83%; ASD dataset: accuracy = 80%). Shared atypical brain connections contributing to classification were mostly present in the default mode network (DMN) and salience network (SN). These functional connections were further related to severity of social deficits in ASD (p = 0.002). Distinct atypical connections were also more related to the DMN and SN, but showed different atypical connectivity patterns between the two disorders. These results suggest some common neural mechanisms contributing to schizophrenia and ASD, and may aid in understanding the pathology of these two neurodevelopmental disorders. Autism Res 2017, 10: 1776-1786. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

LAY SUMMARY

Autism spectrum disorder (ASD) and schizophrenia are two common neurodevelopmental disorders which share several genetic and behavioral features. The present study identified common neural mechanisms contributing to ASD and schizophrenia using resting-state functional MRI data. The results may help to understand the pathology of these two neurodevelopmental disorders.

Family aggregation and risk factors in substance use disorders over three generations in a nation-wide study

Objective

This nation-wide register-based study investigated how often substance use disorders (SUD) and co-morbid disorders occurred in affected families compared to control families.

Method

A total of N = 2504 child and adolescent psychiatric participants who were born between 1969 and 1986 and were registered in the Danish Psychiatric Central Research Register (DPCRR) had a mental disorder before the age of 18 and developed SUD at some point during their life-time. In addition, N = 7472 controls without any psychiatric diagnosis before age 18 and matched for age, sex, and residential region were included. Psychiatric diagnoses of the first-degree relatives were also obtained. A family load component was assessed.

Results

SUD occurred significantly more often in case families than in control families. SUD risk factors included SUD, depression, anxiety disorders, personality disorders, or conduct disorders in the family. Furthermore, male sex, more recent year of birth, and living in the capital city of Copenhagen were also significantly associated with having SUD. The family load explained 30% of the SUD manifestation in the case-probands. The findings in the total SUD group were mostly replicated in the two major subgroups of pure alcohol or multiple substance use disorders.

Discussion

These findings based on a very large and representative dataset provide additional evidence for the strong family aggregation and further risk factors in SUD. The pattern of risk factors is largely the same for the total group of SUD and the major subgroups of pure alcohol and multiple substance use disorders.

Cross-generational influences on childhood anxiety disorders: pathways and mechanisms

Anxiety disorders are common across the lifespan, cause severe distress and impairment, and usually have their onset in childhood. Substantial clinical and epidemiological research has demonstrated the existence of links between anxiety and its disorders in children and parents. Research on the pathways and mechanisms underlying these links has pointed to both behavioral and biological systems. This review synthesizes and summarizes several major aspects of this research. Behavioral systems include vicarious learning, social referencing, and modeling of parental anxiety; overly protective or critical parenting styles; and aspects of parental responses to child anxiety including family accommodation of the child's symptoms. Biological systems include aspects of the prenatal environment affected by maternal anxiety, development and functioning of the oxytocinergic system, and genetic and epigenetic transmission. Implications for the prevention and treatment of child anxiety disorders are discussed, including the potential to enhance child anxiety treatment outcomes through biologically informed parent-based interventions.

Family Aggregation and Risk Factors in Phobic Disorders over Three-Generations in a Nation-Wide Study

Objective

This nation-wide register-based study investigated how often phobic disorders (PHO) and co-morbid disorders occur in affected families compared to control families. Furthermore, the study addressed the impact of sex, year of birth, and degree of urbanization in terms of risk factors.

Method

A total of N = 746 child and adolescent psychiatric participants born between 1969 and 1986 and registered in the Danish Psychiatric Central Research Register (DPCRR) with a diagnosis of a mental disorder before the age of 18, and developed PHO at some point during their life-time until a maximum age of 40 years were included. In addition, N = 2229 controls without any diagnosis of mental disorders before age 18 and that were matched for age, sex, and residential region were included. Diagnoses of mental disorders were also obtained from the first- degree relatives as a part of the Danish Three Generation Study (3GS). A family load component was obtained by using various mixed regression models.

Results

PHO occurred significantly more often in case than in control families, in particular, in mothers and siblings. Substance use disorders (SUD), Depressive disorders (DEP), anxiety disorders (ANX) and personality disorders (PERS) in the family were significantly associated with specific phobia in the case-probands. After controlling for various mental disorders comorbid to PHO it was found that some of the family transmission could be caused by various other mental disorders in family members rather than the PHO itself. Female sex and more recent year of birth were further risk factors while region of residence was not related to the manifestation of PHO. Case-relatives did not develop PHO earlier than control relatives. After adjusting for various additional explanatory variables, the family load explained only 0.0013% of the variance in the manifestation of PHO in the case-probands

Discussion

These findings, based on a very large and representative dataset, provide evidence for the family aggregation and further risk factors in PHO. In contrast to anxiety disorders and other major mental disorders the family load of PHO in this nation-wide study was rather low.

Parental involvement: contribution to childhood anxiety and its treatment

Anxiety disorders are prevalent in youth. Despite demonstrated efficacy of cognitive behavioral therapy (CBT), approximately 40% of anxiety-disordered youth remain unresponsive to treatment. Because developmental and etiological models suggest that parental factors are relevant to the onset and maintenance of childhood anxiety, researchers have proposed and investigated family-based interventions with increased parent work in treatment, aiming to improve the efficacy of treatment for childhood anxiety. However, contrary to what theoretical models suggest, data to date did not indicate additive benefit of family-based CBT in comparison with child-centered modality. Is parent/family involvement unnecessary when treating childhood anxiety disorders? Or could there be the need for specificity (tailored family-based treatment) that is guided by a revised conceptualization that improves the implementation of a family-based intervention? The current review examines (1) relevant parental factors that have been found to be associated with the development and maintenance of childhood anxiety and (2) interventions that incorporate parental involvement. Relevant findings are integrated to formulate a "targeted" treatment approach for parental involvement in CBT for youth anxiety. Specifically, there is potential in the assessment of parent/family factors prior to treatment (for appropriateness) followed by a target-oriented implementation of parent training.

Parental history of psychiatric diagnoses and unipolar depression: a Danish National Register-based cohort study

BACKGROUND

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.

METHOD

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.

RESULTS

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).

CONCLUSIONS

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.

Autism spectrum disorder in individuals with anorexia nervosa and in their first- and second-degree relatives: Danish nationwide register-based cohort-study

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.

A nation-wide study of the family aggregation and risk factors in anorexia nervosa over three generations

OBJECTIVE

This nation-wide register-based study investigated how often anorexia nervosa (AN) and co-morbid disorders occur in affected families compared with control families. Furthermore, the study addressed the impact of sex, year of birth, and degree of urbanization in terms of risk factors.

METHOD

A total of N = 2,370 child and adolescent psychiatric subjects born between 1951 and 1996 and registered in the Danish Psychiatric Central Research Register (DPCRR) had any mental disorder before the age of 18 and developed AN at some point during their life-time. In addition, N = 7,035 controls without any psychiatric diagnosis before age 18 and matched for age, sex, and residential region were included. Psychiatric diagnoses were also obtained on the first-degree relatives as a part of the Danish Three Generation Study (3GS). A family load component was obtained by using various mixed regression models.

RESULTS

AN occurred significantly more often in case than in control families. AN Risk factors included having a sibling with AN, affective disorders in family members, and co-morbid affective, anxiety, obsessive-compulsive, personality, or substance use disorders. Furthermore, female sex, and ascending year of birth were significantly associated with having AN. Urbanization was not related to the family load of AN and case-relatives did not develop AN earlier than control relatives.

DISCUSSION

These findings based on a very large and representative dataset provide evidence for the family aggregation and further risk factors in AN.

Family load estimates and risk factors of anxiety disorders in a nationwide three generation study

The present study investigated how often anxiety disorders with different ages of onset occurred in affected families compared to control families. Furthermore, the study addressed the impact of sex, region of residence, year and month of birth, and parental age at birth. The sample included N=1373 child and adolescent psychiatric participants born between 1952 and 2000 and registered in the Danish Psychiatric Central Register (DPCR) who developed an anxiety disorder before the age of 18. N =4019 controls without any psychiatric diagnosis before age 18, were matched for age, sex, and residential region. Psychiatric diagnoses were also obtained for parents, siblings, and offspring. A family load component was obtained by using various mixed regression models. Anxiety disorders occurred significantly more often in case than in control families. Having a mother, father, or a sibling with the disorder was proven to be a risk factor. Female sex, year of birth, and region of residence were also associated with having an anxiety disorder. Furthermore, case relatives did not develop an anxiety disorder earlier than control relatives. These findings, based on a very large and representative dataset, provide further and solid evidence for the family aggregation of anxiety disorders.

Family aggregation and risk factors of obsessive-compulsive disorders in a nationwide three-generation study

BACKGROUND

This nationwide register-based study investigates how often obsessive-compulsive disorders (OCD) with different age at diagnosis occur in affected families compared to control families. Furthermore, the study addresses the impact of certain risk factors, that is, sex, degree of urbanization, year of birth, and maternal and paternal age at birth.

METHODS

A total of N = 2,057 child and adolescent psychiatric subjects born between 1952 and 2000 and registered in the Danish Psychiatric Central Research Register developed OCD before the age of 18. In addition, N = 6,055 controls without any psychiatric diagnosis before age 18 and matched for age, sex, and residential region were included. Psychiatric diagnoses were also obtained for the first-degree relatives as a part of the Danish Three-Generation Study. A family load component was obtained by using various mixed regression models.

RESULTS

OCD occurred significantly more often in case than in control families. Having a mother, father, sibling, or an offspring with the disorder was proven to be a risk factor. Maternal age above 35 years, male sex by tendency, and ascending year of birth were associated with having OCD. Furthermore, case relatives did not develop OCD earlier than control relatives. The risk of OCD in the case probands was significantly increased when first-degree family members had either OCD, or tic disorders, or affective disorders, or anxiety disorders.

CONCLUSIONS

These findings based on a very large and representative dataset provide further and very solid evidence for the high family aggregation of OCD.

A three generations nation-wide population study of family load estimates in bipolar disorder with different age at onset

OBJECTIVES

This nation-wide register-based study investigates how often bipolar disorder (BD) occurs in affected families compared to control families by estimating the family load as a random effect; this effect measures the degree of dependence among family members in relation to BD. Furthermore, the study addresses the impact of certain risk factors, namely, sex, age at onset of BD, degree of urbanization, year of birth, month of birth, and maternal and paternal age at birth.

METHOD

A total of N=1204 children and adolescent psychiatric cases born between 1950 and 1997 and registered in the Danish Central Psychiatric Register (DPCR) developed BD before the age of 58 years. N=3553 controls without any psychiatric diagnosis were matched for age, gender, and region of residence. Psychiatric diagnoses were also obtained on the relatives, e.g. parents, siblings, and offspring as a part of the Danish Three Generation Study (3GS). A family component was obtained by using different regression models.

RESULTS

Familial factors accounted for 20% of the variation in disease outcome when controlling for year and month of birth, sex, and degree of urbanization. Only female sex was associated with an increased hazard ratio of BD. Also having a mother, father or a sibling with the disorder was proven to be a significant risk factor. Furthermore, case relatives did not develop BD earlier than control relatives.

CONCLUSION

These findings based on a very large and representative dataset provide further and very solid evidence for the high family aggregation of BD.

[Anxiety disorders]

With a lifetime prevalence of approximately 17% anxiety disorders are among the most common mental disorders worldwide. The disease progression can take a chronic course leading to a considerable impairment of the affected person. The current medical classification list (ICD-10) by the World Health Organization differentiates between agoraphobia, social phobia, specific phobia, panic disorder and generalized anxiety disorder. The etiology is multicausal comprising an interaction of genetic and psychosocial factors. For treatment, psychotherapy, psychopharmacological treatment and a combination of both methods are eligible. Anxiety disorders are often associated with physical illness either as the causative factor or the consequence. In particular, anxiety has been identified as an independent risk factor for cardiovascular disease. Anxiety disorders associated with somatic diseases are often unrecognized, therefore an optimization of diagnostic and treatment strategies is necessary.

Suicidal phenotypes associated with family history of suicidal behavior and early traumatic experiences

BACKGROUND

Family history of suicidal behavior and personal history of childhood trauma are risk factors for suicidal behaviors. We hypothesize that subjects with any of these risk factors will show differential features and that subjects with both of them will display more severe phenotypes.

METHODS

This study compares three groups of suicide attempters (n=878): subjects with a family history of suicidal behavior and a personal history of early traumatic experiences, subjects with a family history of suicidal behavior or a personal history of early traumatic experiences, and subjects with neither of these two risk factors, with regards to psychopathology, personality traits and suicidal behavior.

RESULTS

Subjects with a family history of suicidal behavior and childhood trauma were younger at their first suicide attempt and made more frequent, severe and violent attempts when compared with the other groups. Differences in number and precocity of attempts remained after adjustments in a multinomial regression model. Finally, personality profiles were also substantially different in the group with higher impulsiveness, novelty seeking, affective lability and hopelessness.

LIMITATIONS

The information provided by subjects regarding childhood abuse and family history of suicidal behavior was not confirmed by other sources.

CONCLUSIONS

Suicide attempters with a family history of suicidal behavior and childhood trauma show specific characteristics that might be used to prevent future suicidal behaviors in this population. Both risk factors should be routinely investigated when assessing the suicidal risk of a patient.

Family load estimates of schizophrenia and associated risk factors in a nation-wide population study of former child and adolescent patients up to forty years of age

OBJECTIVES

This nation-wide register-based study investigates the family load of schizophrenia (SZ) across three generations in affected families compared to control families. Furthermore the study compares the family load in case vs. control families considering the age of onset of the disorder in the cases. In addition, the study addresses the impact of certain socio-demographic risk factors, i.e. sex, region of residence, year of birth, month of birth, and maternal and paternal age at birth.

METHOD

A total of N=2020 child and adolescent psychiatric cases born between 1969 and 1985 registered in the Danish Central Psychiatric Register (DCPR) before the age of 18 developed SZ before the age of 40. N=5982 controls without any psychiatric diagnosis before age 18 were matched for age, sex, and residential region. Psychiatric diagnoses were also obtained on the first-degree relatives, i.e. parents, siblings, and offspring as a part of the Danish Three Generation Study (3GS). A family load was obtained by using various mixed regression models.

RESULTS

SZ did occur more often in case than in control families. Having a mother, father or a sibling with the disorder was proven to be a risk factor. The year of birth, the region of residence, and paternal age at birth (≥ 35) were associated with SZ. However, the family load was not dependent on age of onset of the case-proband. Furthermore, case relatives did not develop SZ earlier than control relatives.

CONCLUSIONS

These findings based on a very large and representative dataset provide further and solid evidence for the high family aggregation of SZ. The year of birth, the region of residence, and paternal age at birth play an additional role in the development of the disorder.

Examination of the structure of psychopathology using latent class analysis

Several recent studies using factor analytic methods find that the structure of psychopathology reflects broad internalizing and externalizing dimensions, with the internalizing dimension being further divided into fear and distress disorders. Although these variable-centered studies have provided important insights into the structure of psychopathology, they provide limited information about the classification of individual cases. The present study examines patterns of lifetime internalizing and externalizing psychopathology in participants from the Oregon Adolescent Depression Project using latent class analysis that classifies individuals rather than variables. A 4-class solution best fits the data. The largest class (62.5%) included individuals with relatively little psychopathology; 1 class (16.4%) was largely characterized by internalizing disorders, 1 class (16.9%), largely characterized by externalizing disorders; and the final class (4.2%), characterized by both internalizing and externalizing disorders. The validity of the classes was further examined using data on psychiatric morbidity, temperament, and family aggregation of psychopathology. Classes differed on indices of positive, negative, and disinhibited temperament in ways that were consistent with theoretical predictions. Patterns of familial aggregation of psychopathology demonstrated relative specificity of transmission of different disorders. Overall, the findings support conclusions from studies of dimensional models of internalizing and externalizing disorders, and extend them to person-centered approaches to classification.

Following the genes: a framework for animal modeling of psychiatric disorders

The number of individual cases of psychiatric disorders that can be ascribed to identified, rare, single mutations is increasing with great rapidity. Such mutations can be recapitulated in mice to generate animal models with direct etiological validity. Defining the underlying pathogenic mechanisms will require an experimental and theoretical framework to make the links from mutation to altered behavior in an animal or psychopathology in a human. Here, we discuss key elements of such a framework, including cell type-based phenotyping, developmental trajectories, linking circuit properties at micro and macro scales and definition of neurobiological phenotypes that are directly translatable to humans.

Register-based studies of mental disorders

Introduction: Denmark has been pioneering international psychiatric register research for decades. In this article we review central publications, by Danish and international authors, based on data from the Danish Psychiatric Central Research Register and other related registers. Research topics: Our aim was to describe the history, development and achievements of psychiatric research, based on the Danish national registers. The studies considered in this review can be categorized as follows: i) health service research, mainly studies on prevalence and incidence, ii) studies on the outcome of mental disorders, iii) studies on the aetiology of mental disorders. Conclusion: Studies based on Danish registers have provided significant contributions to international psychiatric research. The major advantage of the registers is that they cover the entire population, which makes the conduction of nationwide population-based studies possible. Furthermore, all information in the registers is connected to each citizen’s unique personal identification number, which enables linkage between various registers and biobanks. Such linkage studies have provided important knowledge on the aetiology of mental disorders. Despite inherent limitations about internal and external validity, the Danish national registers have been extremely valuable to international psychiatric research and will continue to play an important role in years to come.

Rethinking the genetic architecture of schizophrenia

BACKGROUND

For many years, the prevailing paradigm has stated that in each individual with schizophrenia (SZ) the genetic risk is due to a combination of many genetic variants, individually of small effect. Recent empirical data are prompting a re-evaluation of this polygenic, common disease-common variant (CDCV) model. Evidence includes a lack of the expected strong positive findings from genome-wide association studies and the concurrent discovery of many different mutations that individually strongly predispose to SZ and other psychiatric disorders. This has led some to adopt a mixed model wherein some cases are caused by polygenic mechanisms and some by single mutations. This model runs counter to a substantial body of theoretical literature that had supposedly conclusively rejected Mendelian inheritance with genetic heterogeneity. Here we ask how this discrepancy between theory and data arose and propose a rationalization of the recent evidence base.

METHOD

In light of recent empirical findings, we reconsider the methods and conclusions of early theoretical analyses and the explicit assumptions underlying them.

RESULTS

We show that many of these assumptions can now be seen to be false and that the model of genetic heterogeneity is consistent with observed familial recurrence risks, endophenotype studies and other population-wide parameters.

CONCLUSIONS

We argue for a more biologically consilient mixed model that involves interactions between disease-causing and disease-modifying variants in each individual. We consider the implications of this model for moving SZ research beyond statistical associations to pathogenic mechanisms.

The genetics of neurodevelopmental disease

The term neurodevelopmental disorder encompasses a wide range of diseases, including recognizably distinct syndromes known to be caused by very rare mutations in specific genes or chromosomal loci, and also much more common disorders such as schizophrenia, autism spectrum disorders, and idiopathic epilepsy and mental retardation. After decades of frustration, the past couple of years have suddenly seen tremendous progress in unravelling the genetics of these common disorders. These findings have led to a paradigm shift in our conception of the genetic architecture of common neurodevelopmental disease, highlighting the importance of individual, rare mutations and overlapping genetic aetiology of various disorders. They have also converged on specific neurodevelopmental pathways, providing insights into pathogenic mechanisms.