The relationship between anxiety disorders and dimensional representations of DSM-IV personality disorders: A co-twin control study

BACKGROUND

There is substantial comorbidity between personality disorders (PDs) and anxiety disorders (ADs). Sharing of familial risk factors possibly explains the co-occurrence, but direct causal relationships between the disorders may also exist.

METHODS

2801 persons from 1391 twin pairs from the Norwegian Institute of Public Health Twin Panel were assessed for all DSM-IV PDs and ADs. Bivariate Poisson-regression analyses were performed to assess whether PDs predicted ADs at three different levels: All PDs combined, PDs combined within DSM-IV-clusters and each individual PD separately. Next, bivariate co-twin control analyses were executed within monozygotic (MZ) and dizygotic (DZ) twin pairs. A similar analytic strategy was employed in multivariate models including PDs as independent variables.

RESULTS

PDs predicted ADs at all levels of analysis in bivariate regression models. Bivariate co-twin control analyses demonstrated an increased risk of ADs in all PDs combined, all PD-clusters and in schizotypal, paranoid, borderline, antisocial, avoidant and dependent PD. In the multivariate regression model, all PD-clusters and schizotypal, borderline, avoidant and obsessive-compulsive PD predicted ADs. Only borderline and avoidant PD predicted ADs in the multivariate co-twin control analysis.

LIMITATIONS

Over-adjustment may explain the results from the multivariate analyses. The cross-sectional study design hampers causal inference.

CONCLUSIONS

Comorbidity between ADs and PDs can be largely accounted for by shared familial risk factors. However, the results are also consistent with a direct causal relationship partly explaining the co-occurrence. Our results indicate specific environmental factors for comorbidity of ADs and borderline and avoidant PDs that are not shared with other PDs.

Longitudinal associations between social anxiety disorder and avoidant personality disorder: A twin study

Social anxiety disorder (SAD) and avoidant personality disorder (AvPD) are frequently co-occurring psychiatric disorders with symptomatology related to fear of social situations. It is uncertain to what degree the 2 disorders reflect the same genetic and environmental risk factors. The current study addresses the stability and co-occurrence of SAD and AvPD, the factor structure of the diagnostic criteria, and genetic and environmental factors underlying the disorders at 2 time points. SAD and AvPD were assessed in 1,761 young adult female twins at baseline and 1,471 of these approximately 10 years later. Biometric models were fitted to dimensional representations of SAD and AvPD. SAD and AvPD were moderately and approximately equally stable from young to middle adulthood, with increasing co-occurrence driven by environmental factors. At the first wave, approximately 1 in 3 individuals with AvPD had SAD, increasing to 1 in 2 at follow-up. The diagnostic criteria for SAD and AvPD had a two-factor structure with low cross-loadings. The relationship between SAD and AvPD was best accounted for by a model with separate, although highly correlated (r = .76), and highly heritable (.66 and .71) risk factors for each disorder. Their genetic and environmental components correlated .84 and .59, respectively. The finding of partially distinct risk factors indicates qualitative differences in the etiology of SAD and AvPD. Genetic factors represented the strongest time-invariant influences, whereas environmental factors were most important at the specific points in time.

A longitudinal, population-based twin study of avoidant and obsessive-compulsive personality disorder traits from early to middle adulthood

BACKGROUND

The phenotypic stability of avoidant personality disorder (AVPD) and obsessive-compulsive personality disorder (OCPD) has previously been found to be moderate. However, little is known about the longitudinal structure of genetic and environmental factors for these disorders separately and jointly, and to what extent genetic and environmental factors contribute to their stability.

METHOD

AVPD and OCPD criteria were assessed using the Structured Interview for DSM-IV Personality in 2793 young adult twins (1385 pairs, 23 singletons) from the Norwegian Institute of Public Health Twin Panel at wave 1 and 2282 (986 pairs, 310 singletons) of these on average 10 years later at wave 2. Longitudinal biometric models were fitted to AVPD and OCPD traits.

RESULTS

For twins who participated at both time-points, the number of endorsed sub-threshold criteria for both personality disorders (PDs) decreased 31% from wave 1 to wave 2. Phenotypic correlations between waves were 0.54 and 0.37 for AVPD and OCPD, respectively. The heritability estimates of the stable PD liabilities were 0.67 for AVPD and 0.53 for OCPD. The genetic correlations were 1.00 for AVPD and 0.72 for OCPD, while the unique environmental influences correlated 0.26 and 0.23, respectively. The correlation between the stable AVPD and OCPD liabilities was 0.39 of which 63% was attributable to genetic influences. Shared environmental factors did not significantly contribute to PD variance at either waves 1 or 2.

CONCLUSION

Phenotypic stability was moderate for AVPD and OCPD traits, and genetic factors contributed more than unique environmental factors to the stability both within and across phenotypes.

A longitudinal twin study of borderline and antisocial personality disorder traits in early to middle adulthood

BACKGROUND

Antisocial personality disorder (ASPD) and borderline personality disorder (BPD) share genetic and environmental risk factors. Little is known about the temporal stability of these etiological factors in adulthood.

METHOD

DSM-IV criteria for ASPD and BPD were assessed using structured interviews in 2282 Norwegian twins in early adulthood and again approximately 10 years later. Longitudinal biometric models were used to analyze the number of endorsed criteria.

RESULTS

The mean criterion count for ASPD and BPD decreased 40% and 28%, respectively, from early to middle adulthood. Rank-order stability was 0.58 for ASPD and 0.45 for BPD. The best-fitting longitudinal twin model included only genetic and individual-specific environmental factors. Genetic effects, both those shared by ASPD and BPD, and those specific to each disorder remained completely stable. The unique environmental effects, however, changed substantially, with a correlation across time of 0.19 for the shared effects, and 0.39 and 0.15, respectively, for those specific to ASPD and BPD. Genetic effects accounted for 71% and 72% of the stability over time for ASPD and BPD, respectively. The genetic and environmental correlations between ASPD and BPD were 0.73, and 0.43, respectively, at both time points.

CONCLUSION

ASPD and BPD traits were moderately stable from early to middle adulthood, mostly due to genetic risk factors which did not change over the 10-year assessment period. Environmental risk factors were mostly transient, and appear to be the main source of phenotypic change. Genetic liability factors were, to a large extent, shared by ASPD and BPD.

Psychosocial factors associated with bulimia nervosa during pregnancy: An internal validation study

OBJECTIVE

The aim of this paper was to internally validate previously reported relations (Knoph Berg et al., Aust N Z J Psychiatry, 42, 396-404, 2008) between psychosocial factors and bulimia nervosa (BN) outcomes during pregnancy.

METHOD

This study is based on the Norwegian Mother and Child Cohort Study (MoBa) conducted by the Norwegian Institute of Public Health. Participants were women enrolled during pregnancy (N = 69,030). Internal validity was evaluated by way of bootstrapped parameter estimates using the overall sample and a split sample calibration approach.

RESULTS

Bootstrap bias estimates were below the problematic threshold, and extend earlier findings (Knoph Berg et al., Aust N Z J Psychiatry, 42, 396-404, 2008) by providing support for the validity of the models at the population level of all pregnant women in Norway. Bootstrap risk ratios indicated that prevalence, incidence, and remission of BN during pregnancy were significantly associated with psychosocial factors. The split sample procedure showed that the models developed on the training sample did not predict risks in the validation sample.

DISCUSSION

This study characterizes associations between psychosocial exposures and BN outcomes among pregnant women in Norway. Women with lifetime and current self-reported psychosocial adversities were at a much higher risk for BN during pregnancy. Psychosocial factors were associated with BN remission during pregnancy, inviting the prospect of enhancing therapeutic interventions. We consider the findings in the context of reproducibility in science.

Medication Use before, during, and after Pregnancy among Women with Eating Disorders: A Study from the Norwegian Mother and Child Cohort Study

INTRODUCTION

Little is known about medication use among women with eating disorders in relation to pregnancy.

AIMS

To explore patterns of and associations between use of psychotropic, gastrointestinal and analgesic medications and eating disorders in the period before, during and after pregnancy.

METHOD

This study is based on the Norwegian Mother and Child Cohort Study (MoBa). A total of 62,019 women, enrolled at approximately 17 weeks' gestation, had valid data from the Norwegian Medical Birth Registry and completed three MoBa questionnaires. The questionnaires provided diagnostic information on broadly defined anorexia nervosa (AN), bulimia nervosa (BN), binge eating disorder (BED) and recurrent self-induced purging in the absence of binge eating (EDNOS-P), along with self-reported use of medication six months before, during, and 0-6 months after pregnancy.

RESULTS

The prevalence of eating disorder subtypes before and/or during pregnancy was: 0.09% AN (n = 54), 0.94% BN (n = 585), 0.10% EDNOS-P (n = 61) and 5.00% BED (n = 3104). The highest over-time prevalence of psychotropic use was within the AN (3.7-22.2%) and EDNOS-P (3.3-9.8%) groups. Compared to controls, BN was directly associated with incident use of psychotropics in pregnancy (adjusted RR: 2.25, 99% CI: 1.17-4.32). Having AN (adjusted RR: 5.11, 99% CI: 1.53-17.01) or EDNOS-P (adjusted RR: 6.77, 99% CI: 1.41-32.53) was directly associated with use of anxiolytics/sedatives postpartum. The estimates of use of analgesics (BED) and laxatives (all eating disorders subtypes) were high at all time periods investigated.

CONCLUSIONS

Use of psychotropic, gastrointestinal, and analgesic medications is extensive among women with eating disorders in the period around pregnancy. Female patients with eating disorders should receive evidence-based counseling about the risk of medication exposure versus the risk of untreated psychiatric illness during pregnancy and postpartum.

Measurement of Total and Free Urinary Phenol and Paraben Concentrations over the Course of Pregnancy: Assessing Reliability and Contamination of Specimens in the Norwegian Mother and Child Cohort Study

BACKGROUND

Exposures to environmental phenols and parabens may be harmful, especially in utero. Prior studies have demonstrated high within-person variability of urinary concentrations across pregnancy.

OBJECTIVES

We sought to measure phenol and paraben biomarker concentrations for the Norwegian Mother and Child Cohort (MoBa) study, assess within-person variability, and investigate any possible external phenol or paraben contamination of specimens.

METHODS

We collected three spot urine samples at approximately 17, 23, and 29 weeks gestation in a hospital setting and added a preservative containing ethyl paraben. We measured urinary concentrations and within-person variability for phenols and parabens in a MoBa sample (n = 45), including a subgroup of 15 participants previously randomly selected for a bisphenol A (BPA) exposure study who had unusually high total BPA concentrations. Additionally, we compared reliability results for total, conjugated, and free concentrations of phenolic compounds.

RESULTS

We detected total and free BPA, butyl paraben, propyl paraben, and methyl paraben in 100% of samples, total benzophenone-3 in 95% of samples, and infrequently detected free benzophenone-3 and total and free 2,4-dichlorophenol and 2,5-dichlorophenol. Intraclass correlation coefficients (ICCs) for total, conjugated, and free concentrations ranged from relatively low for BPA to moderate for propyl paraben. ICCs were generally similar overall and by subgroup.

CONCLUSIONS

Using conjugated concentrations improved reliability estimates only for BPA. Measuring total and free concentrations, an approach that may be useful for future studies, allowed us to identify likely BPA and butyl paraben contamination of archived MoBa urine specimens.

Later emotional and behavioral problems associated with sleep problems in toddlers: a longitudinal study

IMPORTANCE

Childhood sleep problems have been linked to a range of adverse health outcomes, but there is limited knowledge as to the temporal association between sleep problems and subsequent emotional and behavioral problems in young children.

OBJECTIVE

To examine whether sleep problems in toddlers aged 18 months are related to both concurrent and subsequent emotional and behavioral problems in preschool children aged 5 years.

DESIGN, SETTING, AND PARTICIPANTS

A large population-based longitudinal study was conducted in September 2014 using data from the Norwegian Mother and Child Cohort Study conducted at the Norwegian Institute of Public Health from June 1, 1999, to December 31, 2008. A total of 32 662 children or pregnancies were included.

EXPOSURES

Sleep was assessed by mother-reported child sleep duration and nocturnal awakenings.

MAIN OUTCOMES AND MEASURES

Emotional and behavioral problems were measured with items from the Child Behavior Checklist and operationalized according to recommended clinical cutoffs, corresponding to T scores of greater than 65 (93rd percentile). Risk ratios (RRs) were calculated using negative binomial regression, controlling for emotional and behavioral problems at 18 months and other relevant covariates.

RESULTS

Short sleep duration (≤10 hours) in 556 children (1.7%) and frequent nocturnal awakenings (≥3 times) in 1033 children (3.2%) at 18 months significantly predicted both concurrent and later incidence of emotional and behavioral problems at 5 years. The longitudinal RRs were generally larger for internalizing problems, with adjusted RRs of 1.59 (95% CI, 1.23-2.08) for both short sleep duration and 1.57 (95% CI, 1.28-1.93) for nocturnal awakenings; RRs for externalizing problems were 1.77 (95% CI, 1.37-2.30) and 1.25 (95% CI, 1.00-1.58), respectively. Additional adjustment for emotional and behavioral problems at 18 months slightly reduced the strength of these associations, and all RRs remained significant in the fully adjusted models.

CONCLUSIONS AND RELEVANCE

Early sleep problems predict later development of emotional and behavioral problems. Intervention studies are needed to examine whether sleep programs targeting early childhood may avert the onset of later adverse outcomes.

A longitudinal twin study of cluster A personality disorders

BACKGROUND

While cluster A personality disorders (PDs) have been shown to be moderately heritable, we know little about the temporal stability of these genetic risk factors.

METHOD

Paranoid PD (PPD) and schizotypal PD (STPD) were assessed using the Structured Interview for DSM-IV Personality in 2793 young adult twins from the Norwegian Institute of Public Health Twin Panel at wave 1 and 2282 twins on average 10 years later at wave 2. Using the program Mx, we fitted a longitudinal latent factor model using the number of endorsed criteria for PPD and STPD.

RESULTS

The stability over time of the criteria counts for PPD and STPD, estimated as polychoric correlations, were +0.34 and +0.40, respectively. The best-fit longitudinal model included only additive genetic and individual-specific environmental factors with parameter estimates constrained to equality across the two waves. The cross-wave genetic and individual-specific environmental correlations for a latent cluster A factor were estimated to equal +1.00 and +0.13, respectively. The cross-time correlations for genetic and environmental effects specific to the individual PDs were estimated at +1.00 and +0.16-0.20, respectively. We found that 68% and 71% of the temporal stability of PPD and STPD derived, respectively, from the effect of genetic factors.

CONCLUSION

Shared genetic risk factors for two of the cluster A PDs are highly stable in adults over a 10-year period while environmental risk factors are relatively transient. Over two-thirds of the long-term stability of the common cluster A PD liability can be attributed to genetic influences.

Weight-for-length trajectories in the first year of life in children of mothers with eating disorders in a large Norwegian Cohort

OBJECTIVE

To describe weight-for-length (WFL) trajectories in the children (birth-12 months) of mothers with and without eating disorders.

METHOD

This study is based on the Norwegian Mother and Child Cohort Study (MoBa) conducted by the Norwegian Institute of Public Health. We categorized women (N = 57,185) based on diagnosis prior to and during pregnancy: anorexia nervosa, bulimia nervosa, eating disorder not otherwise specified-purging subtype, binge eating disorder, or no eating disorder. The primary analysis included a shape invariant model fitted with nonlinear mixed effects to compare growth rates across eating disorder subtypes.

RESULTS

The children of mothers reporting any eating disorder had a lower WFL growth rate from birth to 12 months than the children of mothers without eating disorders, even after adjusting for relative birth weight and some confounders known to affect growth.

DISCUSSION

In this cohort, child WFL was related to maternal eating disorder status before and/or during pregnancy. These differences in growth trajectories warrant further study of long-term health outcomes and, if replicated, tailoring counseling to mothers with eating disorders during pregnancy.

Association of maternal report of infant and toddler gastrointestinal symptoms with autism: evidence from a prospective birth cohort

IMPORTANCE

Gastrointestinal (GI) comorbidities are frequently described in association with autism spectrum disorder (ASD). However, the prevalence of GI disturbances and the age at which such problems first appear are unclear, and their specificity for ASD compared with other neurodevelopmental disorders is uncertain.

OBJECTIVE

To compare maternal report of GI symptoms during the first 3 years of life in children with ASD, developmental delay (DD), and typical development (TD).

DESIGN, SETTING, AND PARTICIPANTS

This large prospective cohort study consists of participants in the Norwegian Mother and Child Cohort Study. During a 10-year period (January 1, 1999, through December 31, 2008), women throughout Norway were recruited at the first prenatal ultrasonographic visit (approximately 18 weeks' gestation). The study enrolled 95,278 mothers, 75,248 fathers, and 114,516 children. Our analyses are based on MoBa data released through October 1, 2013, and NPR diagnoses registered through December 31, 2012, and include children born from January 1, 2002, through December 31, 2008, with completed age 18- and 36-month questionnaires.

EXPOSURES

We defined 3 groups of children: children with ASD (n = 195), children with DD and delayed language and/or motor development (n = 4636), and children with TD (n = 40 ,95).

MAIN OUTCOMES AND MEASURES

The GI symptoms were based on maternal report of constipation, diarrhea, and food allergy/intolerance.

RESULTS

Children with ASD were at significantly increased odds of maternally reported constipation (adjusted odds ratio [aOR], 2.7; 95% CI, 1.9-3.8; P < .001) and food allergy/intolerance (aOR, 1.7; 95% CI, 1.1-2.6; P = .01) in the 6- to 18-month-old age period and diarrhea (aOR, 2.3; 95% CI, 1.5-3.6; P < .001), constipation (aOR, 1.6; 95% CI, 1.2-2.3; P < .01), and food allergy/intolerance (aOR, 2.0; 95% CI, 1.3-3.1; P < .01) in the 18- to 36-month-old age period compared with children with TD. Similar results for these symptom categories were observed in comparisons with children with DD, but ORs were slightly lower. Mothers of children with ASD were significantly more likely to report 1 or more GI symptom in either the 6- to 18-month or the 18- to 36-month-old age period and more than twice as likely to report at least 1 GI symptom in both age periods compared with mothers of children with TD or DD.

CONCLUSIONS AND RELEVANCE

In this large prospective cohort, maternally reported GI symptoms are more common and more often persistent during the first 3 years of life in children with ASD than in children with TD or DD.

Parent ratings of executive function in young preschool children with symptoms of attention-deficit/-hyperactivity disorder

BACKGROUND

Recent research has demonstrated that deficits in basic, self-regulatory processes, or executive function (EF), may be related to symptoms of attention-deficit/hyperactivity disorder (ADHD) already during the preschool period. As the majority of studies investigating these relations in young children have been based primarily on clinically administered tests, it is not clear how early symptoms of ADHD may be related to observations of EF in an everyday context. The preschool version of the Behavior Rating Inventory of Executive Function (BRIEF-P) was developed to provide information about EF through observable, behavioral manifestations of self-regulation, and is the most commonly used rating scale for EF assessment in children.

METHODS

Relations between symptoms of ADHD reported in the Preschool Age Psychiatric Assessment interview (PAPA), and EF as measured by the BRIEF-P (parent form), were investigated in a large, nonreferred sample of preschool children (37-47 months, n = 1134) recruited from the Norwegian Mother and Child Cohort Study (MoBa) at the Norwegian Institute of Public Health. The inventory's discriminative ability was examined in a subsample consisting of children who met the diagnostic criteria for either ADHD, oppositional defiant disorder (ODD) or anxiety disorder, and typically developing controls (n = 308). The four groups were also compared with regard to patterns of EF difficulties reported in the BRIEF-P.

RESULTS

Of the five BRIEF-P subscales, Inhibit and Working Memory were the two most closely related to ADHD symptoms, together explaining 38.5% of the variance in PAPA symptom ratings. Based on their scores on the Inhibit and Working Memory subscales (combined), 86.4% of the children in the ADHD and TD groups were correctly classified. ADHD symptoms were associated with more severe difficulties across EF domains, and a different EF profile in comparison to children with other symptoms (anxiety, ODD) and to typically developing controls.

CONCLUSIONS

Early symptoms of ADHD were linked to parent-reported difficulties primarily within inhibition and working memory, suggesting that deficiencies within these two EF domains characterize early forms of ADHD. Our findings support the clinical utility of the BRIEF-P as a measure of EF in young preschool children with symptoms of ADHD.

Genome-wide analysis of attention deficit hyperactivity disorder in Norway

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is a highly heritable neuropsychiatric condition, but it has been difficult to identify genes underlying this disorder. This study aimed to explore genetics of ADHD in an ethnically homogeneous Norwegian population by means of a genome-wide association (GWA) analysis followed by examination of candidate loci.

MATERIALS AND METHODS

Participants were recruited through Norwegian medical and birth registries as well as the general population. Presence of ADHD was defined according to DSM-IV criteria. Genotyping was performed using Illumina Human OmniExpress-12v1 microarrays. Statistical analyses were divided into several steps: (1) genome-wide association in the form of logistic regression in PLINK and follow-up pathway analyses performed in DAPPLE and INRICH softwares, (2) SNP-heritability calculated using genome-wide complex trait analysis (GCTA) tool, (3) gene-based association tests carried out in JAG software, and (4) evaluation of previously reported genome-wide signals and candidate genes of ADHD.

RESULTS

In total, 1.358 individuals (478 cases and 880 controls) and 598.384 autosomal SNPs were subjected to GWA analysis. No single polymorphism reached genome-wide significance. The strongest signal was observed at rs9949006 in the ENSG00000263745 gene (OR=1.51, 95% CI 1.28-1.79, p=1.38E-06). Pathway analyses of the top SNPs implicated genes involved in the regulation of gene expression, cell adhesion and inflammation. Among previously identified ADHD candidate genes, prominent association signals were observed for SLC9A9 (rs1393072, OR=1.46, 95% CI = 1.21-1.77, p=9.95E-05) and TPH2 (rs17110690, OR = 1.38, 95% CI = 1.14-1.66, p=8.31E-04).

CONCLUSION

This study confirms the complexity and heterogeneity of ADHD etiology. Taken together with previous findings, our results point to a spectrum of biological mechanisms underlying the symptoms of ADHD, providing targets for further genetic exploration of this complex disorder.

Socioeconomic status and sick leave granted for mental and somatic disorders: a prospective study of young adult twins

Background

Low socioeconomic status (SES), indicated by low income and education, has consistently been found to be a strong predictor of sick leave. Several possible pathways from SES to sick leave have been described in previous literature, but there are also evidence indicating that the association can be confounded by common underlying factors. This study utilizes a population-based sample of employed young adult twins to estimate (i) the degree to which education and income are prospectively related to sick leave granted for mental, somatic, and any disorder, and (ii) whether these associations are confounded by familial factors.

Methods

Registry data on educational attainment and income at age 30 and subsequent sick leave were available for 6,103 employed young adult twins, among which there were 2,024 complete twin pairs. The average follow-up time was 6.57 years. Individual-level associations and fixed effects within twin pairs were estimated.

Results

Low education and income were associated with sick leave granted for both mental and somatic disorders, and with sick leave granted for any disorder. Associations were attenuated within dizygotic twin pairs and reduced to non-significance within monozygotic twin pairs, suggesting influence of familial factors on the associations between SES and sick leave.

Conclusions

Low SES is associated with a higher level of sick leave granted for both mental and somatic disorders among young adults, but these associations are confounded by factors that are common to co-twins. Education and income are therefore not likely to strongly affect sick leave in young adulthood.

Factor structure of the Behavior Rating Inventory of Executive Functions (BRIEF-P) at age three years

The preschool period is an important developmental period for the emergence of cognitive self-regulatory skills or executive functions (EF). To date, evidence regarding the structure of EF in preschool children has supported both unitary and multicomponent models. The aim of the present study was to test the factor structure of early EF as measured by the Behavior Rating Inventory of Executive Function-Preschool version (BRIEF-P). BRIEF-P consists of five subscales and three broader indexes, hypothesized to tap into different subcomponents of EF. Parent ratings of EF from a nonreferred sample of children recruited from the Norwegian Mother and Child Cohort Study (N = 1134; age range 37-47 months) were subjected to confirmatory factor analyses (CFA). Three theoretically derived models were assessed; the second-order three-factor model originally proposed by the BRIEF-P authors, a "true" first-order one-factor model and a second-order one-factor model. CFA fit statistics supported the original three-factor solution. However, the difference in fit was marginal between this model and the second-order one-factor model. A follow-up exploratory factor analysis (EFA) supported the existence of several factors underlying EF in early preschool years, with a considerable overlap with the five BRIEF-P subscales. Our results suggest that some differentiation in EF has taken place at age 3 years, which is reflected in behavior ratings. The internal consistency of the BRIEF-P five clinical subscales is supported. Subscale interrelations may, however, differ at this age from those observed in the preschool group as a whole.

Multiple births and maternal mental health from pregnancy to 5 years after birth: A longitudinal population-based cohort study

<p><em>Background:</em> There is a lack of population-based studies on multiple births and maternal mental health. Having a high-risk pregnancy by bearing two or more children is a stressful life event, and the challenges of parenting two or more children probably also lead to a high level of parental stress. There are a few results on multiple births and maternal mental health from studies on in vitro fertilization samples. The only previous cohort study on multiple birth and maternal mental health included a single measure of depressive symptoms at 9 months postpartum. We aim to estimate the relative risk for depression and anxiety after multiple birth in a population-based prospective cohort study while adjusting for factors prior and subsequent to fertilization.</p><p><em>Methods</em>: We used data from 87,807 pregnancies included in the Norwegian Mother and Child Cohort study. Information on multiple birth was retrieved from the Norwegian Medical Birth Registry, and maternal mental health was assessed at 17th and 30th week of gestation and 0.5, 1.5, 3, and 5 years postpartum. There were 1,842 plural births included in the study (i.e. 1,821 twin births and 21 higher order births). We predicted maternal mental health at each time point, subsequently adjusting for 1) factors prior to fertilization (e.g. maternal age and in vitro fertilization); 2) factors during pregnancy (e.g. hypertensive states); 3) factors at delivery (e.g. cesarean section); 4) child-related postnatal complications (e.g. intracranial hemorrhage); and 5) concurrent depression or anxiety after pregnancy.</p><p><em>Results</em>: Adjusted for antecedents of plural birth, mothers expecting a plural birth had a normal risk for anxiety (RR=1.05; 95% CI 0.92-1.20) and depression (RR=1.02; 95% CI 0.89-1.16) at 17th week of gestation. However, plural birth was associated with maternal depression at 1.5, 3, and 5 years postpartum and maternal anxiety at 3 years postpartum. The trend was for the association to increase across time, and mothers of multiplets had a significant higher risk for depression at 5 years (RR=1.77; 95% CI 1.33-2.35). Fully adjusted the RR for depression was 1.51 (95% CI 1.10-2.08). By adjusting depression for concurrent anxiety, and vice versa we found the effect of multiple pregnancy to be specific to depression and not anxiety.</p><p><em>Conclusions:</em> Mothers expecting multiplets have normal mental health during pregnancy. After birth there is an increasing risk for depression up to 5 years of age. Our findings indicate that more is simply more, and mothers of multiplets have need for additional support several years postpartum</p>

The Autism Birth Cohort (ABC):a study of autism spectrum disorders in MoBa

Background: Autism spectrum disorders (ASDs) are characterized by persistent deficits in social communication and interaction and restricted, repetitive patterns of behavior, interests or activities. In most cases, the cause of ASD is likely to be a combination of genetic predisposition and environmental exposures occurring in fetal life or early infancy. Consequently, a prospective pregnancy cohort like MoBa represents an ideal platform for studies of ASDs in children.Methods: The Autism Birth Cohort (ABC) Study has identified potential ASD cases in MoBa through questionnaire- based screening, parental and professional referrals, and linkages to the Norwegian Patient Register. ASD diagnoses have been ascertained through in-person clinical assessments and medical record reviews.Current results: By the end of 2012, the ABC Study had identified 518 ASD cases in MoBa. The ASD prevalence in school-age children is 0.7-0.8%, which is in line with nationwide estimates for Norway. The most important source of ASD case identification was registry linkages, while only a minority was detected through early screening. Published findings show that screening at 18 months misses the majority of ASD cases. Analyses of risk factors for ASDs have shown that maternal use of folic acid supplements in early pregnancy may lower the child’s risk of developing ASDs and that paternal obesity appears to increase the child’s risk of ASDs.Future plans: ASD case identification will continue through annual registry linkages and subsequent reviews of medical records. Analyses of plasma samples and RNA samples will be conducted to investigate prenatal and perinatal microbial exposures, innate immune and inflammatory responses, biomarkers of autism risk, and exposures to xenobiotics. Analyses of deciduous teeth will also investigate the effect of medications and environmental toxins. Exome sequencing of DNA from ASD cases and their parents is ongoing, and will elucidate the role of de novo DNA mutations in the pathogenesis of ASDs. Future epidemiological analyses will explore the results of the 36-month screening for ASDs, the diagnostic stability and developmental trajectories in ASD children, and psychiatric and medical comorbidities in ASDs.

Eating Disorders, Pregnancy, and the Postpartum Period: Findings from the Norwegian Mother and Child Cohort Study (MoBa)

This review summarizes studies on eating disorders in pregnancy and the postpartum period that have been conducted as part of the broader Norwegian Mother and Child Cohort Study (MoBa). Prior to the 2000s, empirical literature on eating disorders in pregnancy was sparse and consisted mostly of studies in small clinical samples. MoBa has contributed to a new era of research by making population-based and large-sample research possible. To date, MoBa has led to 19 studies on diverse questions including the prevalence, course, and risk correlates of eating disorders during pregnancy and the postpartum. The associations between eating disorder exposure and pregnancy, birth and obstetric outcomes, and maternal and offspring health and well-being, have also been areas of focus. The findings indicate that eating disorders in pregnancy are relatively common and appear to confer health risks to mother and her child related to sleep, birth outcomes, maternal nutrition, and child feeding and eating.

Personality disorders are important risk factors for disability pensioning

PURPOSE

To determine whether personality disorders (PDs) are associated with increased risk of disability pensioning in young adults, independent of other common mental disorders.

METHODS

2,770 young adults from the general population were assessed for PDs by the Structured Interview for DSM-IV Personality, and for common mental disorders by the Composite of International Diagnostic Interview. These data were linked to the Norwegian National Insurance Administration's recordings of disability benefits for a 10-year period. Logistic regression analyses were applied to investigate the association between PDs and disability pensioning. The analyses were conducted for three types of PD measures: categorical diagnoses (any PD), dimensional scores of individual PDs and higher order components retrieved by principal component analyses.

RESULTS

Having any PD was strongly associated with disability pensioning, regardless of disability diagnosis. The estimated odds ratio (OR) was substantially higher for PDs [OR 4.69 (95% confidence interval (CI) 2.6-8.5)] than for mood disorders [OR 1.3 (CI 0.7-2.3)] and anxiety disorders [OR 2.3 (CI 1.3-4.3)]. Measured dimensionally, all PD traits except antisocial traits were significantly associated with disability pensioning. After adjusting for co-occurring traits of other PDs, only schizoid, dependent and borderline PD traits showed a significant positive association with disability pension, while antisocial traits showed a significant negative association. The principal component analyses showed that negative affectivity, psychoticism, and detachment was associated with an increased risk of disability pensioning, while antagonism/disinhibition and obsessivity were not.

CONCLUSIONS

PDs are strongly associated with disability pensioning in young adults, and might be more important predictors of work disability than anxiety and depressive disorders. Certain aspects of pathologic personalities are particularly important predictors of disability.

Early age of alcohol initiation is not the cause of alcohol use disorders in adulthood, but is a major indicator of genetic risk. A population-based twin study

BACKGROUND AND AIMS

An early age of alcohol initiation (AAI) is associated with and has been hypothesized to be a cause of alcohol use disorders (AUD) in adulthood. Results from twin studies, however, indicate that AAI is an indicator of risk for AUD. We aimed to test a causal hypothesis versus a risk indicator hypothesis for the relationship between early AAI and AUD.

DESIGN

A population-based twin study using biometric twin modelling.

SETTING

Norway.

PARTICIPANTS

A population-based sample of 1336 Norwegian twins.

MEASUREMENTS

Life-time DSM-IV AUDs were assessed by structured clinical interview and AAI by questionnaire.

FINDINGS

The risk indicator model in which the association between AAI and AUD was explained by common vulnerability was the best fitted to the data. The heritability was 37% [95% confidence interval (CI) = 21%, 53%] for AAI and 62% (95% CI = 51%, 73%) for AUD. Genetic risk for AAI accounted for 44% (95% CI = 17%, 71%) of the total genetic risk for AUD and the correlation between genetic factors for AAI and AUD was -0.66 (95%CI -0.87, -0.46). Individual-specific environmental risk for AAI explained only 1% (95% CI = 0%, 3%) of the risk for AUD. Shared environmental factors did not influence AUD, but accounted for 25% (95% CI = 7%, 35%) of the variance in AAI.

CONCLUSIONS

The association between early age of alcohol initiation and alcohol use disorders in later life does not reflect a causal relationship, but is due almost entirely to common genetic risk factors.

Maternal eating disorder and infant diet. A latent class analysis based on the Norwegian Mother and Child Cohort Study (MoBa)

Knowledge of infant diet and feeding practices among children of mothers with eating disorders is essential to promote healthy eating in these children. This study compared the dietary patterns of 6-month-old children of mothers with anorexia nervosa, bulimia nervosa, binge eating disorder, and eating disorder not otherwise specified-purging subtype, to the diet of children of mothers with no eating disorders (reference group). The study was based on 53,879 mothers in the Norwegian Mother and Child Cohort Study (MoBa). Latent class analysis (LCA) was used to identify discrete latent classes of infant diet based on the mothers' responses to questions about 16 food items. LCA identified five classes, characterized by primarily homemade vegetarian food (4% of infants), homemade traditional food (8%), commercial cereals (35%), commercial jarred baby food (39%), and a mix of all food groups (11%). The association between latent dietary classes and maternal eating disorders were estimated by multinomial logistic regression. Infants of mothers with bulimia nervosa had a lower probability of being in the homemade traditional food class compared to the commercial jarred baby food class, than the referent (O.R. 0.59; 95% CI 0.36-0.99). Infants of mothers with binge eating disorder had a lower probability of being in the homemade vegetarian class compared to the commercial jarred baby food class (O.R. 0.77; 95% CI 0.60-0.99), but only before adjusting for relevant confounders. Anorexia nervosa and eating disorder not otherwise specified-purging subtype were not statistically significantly associated with any of the dietary classes. These results suggest that maternal eating disorders may to some extent influence the child's diet at 6 months; however, the extent to which these differences influence child health and development remains an area for further inquiry.

A genome-wide association study of anorexia nervosa

Anorexia nervosa (AN) is a complex and heritable eating disorder characterized by dangerously low body weight. Neither candidate gene studies nor an initial genome-wide association study (GWAS) have yielded significant and replicated results. We performed a GWAS in 2907 cases with AN from 14 countries (15 sites) and 14 860 ancestrally matched controls as part of the Genetic Consortium for AN (GCAN) and the Wellcome Trust Case Control Consortium 3 (WTCCC3). Individual association analyses were conducted in each stratum and meta-analyzed across all 15 discovery data sets. Seventy-six (72 independent) single nucleotide polymorphisms were taken forward for in silico (two data sets) or de novo (13 data sets) replication genotyping in 2677 independent AN cases and 8629 European ancestry controls along with 458 AN cases and 421 controls from Japan. The final global meta-analysis across discovery and replication data sets comprised 5551 AN cases and 21 080 controls. AN subtype analyses (1606 AN restricting; 1445 AN binge-purge) were performed. No findings reached genome-wide significance. Two intronic variants were suggestively associated: rs9839776 (P=3.01 × 10(-7)) in SOX2OT and rs17030795 (P=5.84 × 10(-6)) in PPP3CA. Two additional signals were specific to Europeans: rs1523921 (P=5.76 × 10(-)(6)) between CUL3 and FAM124B and rs1886797 (P=8.05 × 10(-)(6)) near SPATA13. Comparing discovery with replication results, 76% of the effects were in the same direction, an observation highly unlikely to be due to chance (P=4 × 10(-6)), strongly suggesting that true findings exist but our sample, the largest yet reported, was underpowered for their detection. The accrual of large genotyped AN case-control samples should be an immediate priority for the field.

Gestational and postpartum weight change patterns in mothers with eating disorders

BACKGROUND

Although pregnancy can be associated with adaptive changes in weight and eating behaviour for women with eating disorders, less is known about whether these changes are maintained in the postpartum period. We used a longitudinal design to examine gestational and postpartum weight trajectories in mothers with and without eating disorders in the Norwegian Mother and Child Cohort Study (MoBa) conducted by the Norwegian Institute of Public Health.

METHODS

Fifty-six women reported anorexia nervosa (AN), 636 bulimia nervosa, 3327 binge eating disorder and 69 eating disorder not otherwise specified, purging type. The referent group included 61,233 mothers with no eating disorder. We used a mixed effects model to predict weight change over time by eating disorder subtype.

RESULTS

Mothers with AN, bulimia nervosa, binge eating disorder and eating disorder not otherwise specified had greater increases in body mass index (BMI) during pregnancy and greater decreases in BMI over the first 6 months postpartum. Women with AN shifted from the underweight BMI range before pregnancy to the normal weight range at 36 months postpartum

CONCLUSIONS

Patterns of maternal weight gain and retention during the perinatal period vary across eating disorder subtype and warrant clinical attention.

Reliability of triclosan measures in repeated urine samples from Norwegian pregnant women

Triclosan (TCS) is a synthetic antibacterial chemical that is used in personal care products and is measurable in urine. Urinary TCS has been associated with allergy in children in Norway and the United States. A reasonable degree of temporal reliability of TCS urinary concentrations has been reported among US children as well as for Puerto Rican pregnant women. We examined the reliability of TCS measures in urine among Norwegian pregnant women. TCS was measured in spot urine samples collected in gestational weeks 17, 23, and 29 from 45 women in The Norwegian Mother and Child Cohort Study (MoBa) enrolled in 2007 and 2008. Spearman's rank correlation coefficient (rs) and intraclass correlation coefficient (ICC) statistics were calculated. Fifty-six percent of the 45 women had a least one sample with a value above the method limit of detection (2.3 μg/l). The correlation coefficients were 0.61 for TCS concentrations at 17 and 23 weeks and 0.49 for concentrations at 17 and 29 weeks. For the three time points, the ICC was 0.49. The reliability of TCS concentrations in repeated urine samples from pregnant Norwegian women was reasonably good, suggesting a single urine sample can adequately represent TCS exposure during pregnancy.

Childhood trauma and personality disorder criterion counts: a co-twin control analysis

Correlational studies consistently report relationships between childhood trauma (CT) and most personality disorder (PD) criteria and diagnoses. However, it is not clear whether CT is directly related to PDs or whether common familial factors (i.e., shared environment and/or genetic factors) better account for that relationship. The current study used a cotwin control design to examine support for a direct effect of CT on PD criterion counts. Participants were from the Norwegian Twin Registry (N = 2,780), including a subset (n = 898) of twin pairs (449 pairs, 45% monozygotic [MZ]) discordant for CT meeting DSM-IV Posttraumatic Stress Disorder Criterion A. All participants completed the Norwegian version of the Structured Interview for DSM-IV Personality. Significant associations between CT and all PD criterion counts were detected in the general sample; however, the magnitude of observed effects was small, with CT accounting for no more than approximately 1% of variance in PD criterion counts. A significant, yet modest, interactive effect was detected for sex and CT on Schizoid and Schizotypal PD criterion counts, with CT being related to these disorders among women but not men. After common familial factors were accounted for in the discordant twin sample, CT was significantly related to Borderline and Antisocial PD criterion counts, but no other disorders; however, the magnitude of observed effects was quite modest (r2 = .006 for both outcomes), indicating that the small effect observed in the full sample is likely better accounted for by common genetic and/or environmental factors. CT does not appear to be a key factor in PD etiology.