The Norwegian Institute of Public Health twin study of mental health: examining recruitment and attrition bias

Common genetic and environmental risk for personality disorders and psychotic-like experiences in young adult twins

INTRODUCTION

Psychotic-like experiences (PLE) have been associated with the subsequent emergence of psychotic disorders as well as several other domains of psychopathology. In this twin study, we estimated the genetic and environmental correlations between PLE and 10 personality disorders (PD).

METHODS

Diagnoses of 10 PDs according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) and PLE from the Composite International Diagnostic Interview (CIDI) were retrieved for 2793 young adult twins from the Norwegian Twin Registry. Risk for having a PD and PLEs was modeled using item response theory. Biometric twin models were fitted to estimate the genetic and environmental correlations between PDs and PLEs. Co-twin control analysis was performed to estimate additional within-family risk for PLEs when having a PD.

RESULTS

Phenotypic overlap between PDs and PLEs ranged from 14% to 44% in males and from 11% to 39% in females, with the highest overlap for borderline PD in both sexes. In general, we found higher genetic correlations (r = 0.14-0.72) than environmental correlations (r = 0.06-0.28) between PDs and PLEs. The highest genetic correlations between PLE and PDs were found for borderline (r = 0.72), paranoid (r = 0.56), schizotypal (r = 0.56) and antisocial PD (r = 0.49).

CONCLUSION

We found that the co-occurrence between PDs and PLE is the best explained by shared genetic determinants, with minor contributions from environmental factors. Interestingly, borderline PD was highly genetically correlated with PLE, warranting molecular genetic studies of this association.

Per- and polyfluoroalkyl substances and sleep health in U.S. adults, NHANES 2005-2014

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals that induce oxidative inflammatory responses and disrupt the endocrine and central nervous systems, all of which can influence sleep.

OBJECTIVE

To investigate the association between PFAS exposure and sleep health measures in U.S. adults.

METHODS

We analyzed serum concentration data of four PFAS [perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA)] reported for 8913 adults in NHANES 2005-2014. Sleep outcomes, including trouble sleeping, having a diagnosis of sleep disorder, and recent daily sleep duration classified as insufficient or excessive sleep (<6 or >9 h/day) were examined. Weighted logistic regression was used to estimate the association between the sleep outcomes and each PFAS modeled continuously (log2) or in exposure tertiles. We applied quantile g-computation to estimate the effect of the four PFAS as a mixture on the sleep outcomes. We conducted a quantitative bias analysis to assess the potential influence of self-selection and uncontrolled confounding.

RESULTS

We observed some inverse associations between serum PFAS and trouble sleeping or sleep disorder, which were more consistent for PFOS (e.g., per log2-PFOS (ng/ml) and trouble sleeping OR = 0.93, 95%CI: 0.89, 0.98; sleep disorder OR = 0.89, 95%CI: 0.83, 0.95). Per quartile increase of the PFAS mixture was inversely associated with trouble sleeping and sleep disorder. No consistent associations were found for sleep duration across analyses. Our bias analysis suggests that the finding on sleep disorder could be explained by a moderate level of self-selection and negative confounding effects.

CONCLUSIONS

We found no evidence to suggest exposure to four legacy PFAS worsened self-reported sleep health among U.S. adults. While some inverse associations between specific PFAS and sleep disorder were observed, self-selection and uncontrolled confounding biases may play a role in these findings.

A randomized controlled trial of 6-month dental home visits on 24-month caries incidence in preschool children

OBJECTIVES

This paper reports on the effect of 6-month dental home visits compared to no dental home visits on 24-month caries incidence in 5- to 6-year-olds.

METHODS

5- to 6-year-olds attending kindergartens were randomized to receive either 6-month dental home visits and education leaflets (Intervention group) or education leaflets alone (Control group) over 24 months. To detect a 15% difference in caries incidence with a significance level of 5% and power of 80%, 88 children were calculated to be needed in the Intervention group and 88 in the Control. Baseline clinical data included oral examinations at the kindergartens. Follow-up visits were made on the 6th, 12th and 18th month. At the end of the 24 months, both the Intervention and Control groups were visited for oral examinations. The primary outcome was caries incidence, measured by the number and proportion of children who developed new caries in the primary molars after 24 months. The secondary outcome was the number of primary molars that developed new caries (d-pms). Frequency distributions of participants by baseline socio-demographic characteristics and caries experience were calculated. The chi-square test was used to test differences between the caries experience in the Intervention and Control groups. The t test was used to compare the mean number of primary molars developing new caries between the Intervention Group and the Control Group. The number of children needed to treat (NNT) was also calculated.

RESULTS

At the 24-month follow-up, 19 (14.4%) developed new caries in the Intervention Group, compared to 60 (60.0%) in the Control Group (p = .001). On average, 0.2 (95% CI = 0.1-0.3) tooth per child in the Intervention Group was observed to have developed new caries compared to 1.1 (95% CI = 0.8-1.3) tooth per child in the Control Group (p = .001). The number of children needed to treat (NNT) to prevent one child from developing new caries was 2.2.

CONCLUSIONS

The present study has demonstrated that 6-month home visits to families of 5- to 6-year-olds are effective in caries prevention in 5- to 6-year-olds of low-income families in a middle-income country where access to health services, including oral health promotion services, is limited.

Physical activity changes among office workers during the COVID-19 pandemic lockdown and the agreement between objective and subjective physical activity metrics

After the onset of the COVID-19 pandemic, many office workers transitioned to working-from-home (WFH) which altered routine physical activity (PA). To understand how these workers' PA were affected throughout the pandemic, PA data collected in January, April, June, and December 2020 with an activity tracker and a validated survey were analyzed. Between January and December, it was found that step counts during the weekday decreased (p < 0.01), weekday heart rate was higher than weekends (p < 0.01), activity-tracker and self-reported PA decreased (p < 0.01), and sitting time increased (p < 0.01). To understand the agreement between the objective and subjective METs, Bland-Altman analyses were completed and demonstrated an acceptable level of agreement. Findings show decreased level of PA amongst WFH office workers and that the activity tracker and survey are reliable methods of recording WFH PA.

Psychotic-like experiences from adolescence to adulthood: A longitudinal study

Psychotic-like experiences (PLEs), such as delusions and hallucinations, are regarded to occur along a spectrum and to be present also in non-help-seeking individuals from the general population. However, it remains unclear whether the occurrence of PLEs is a unique risk factor for future PLEs or a symptom of general psychopathology. In this study, we investigated whether PLEs during adolescence predict future PLEs in adulthood. A community-based cohort of 1146 young adolescents (mean age, 14.38 years) were assessed and then reassessed 6 years later (mean age, 20.15 years). Participants reported PLEs experienced in the past year, as well as symptoms of depression, anxiety, attention-deficit/hyperactivity disorder, and conduct problems. We adjusted the analysis for other forms of psychopathology and sex differences. Participants who reported PLEs in adulthood had higher ratings for all preceding and co-occurring symptoms of psychopathology. In the adjusted logistic regression model, having PLEs and, to a smaller degree, anxiety during adolescence predicted PLEs in early adulthood. The association between baseline and future PLEs did not differ between males and females, although females were more likely to report PLEs during adolescence. Participants with persistent PLEs reported more hallucinations during adolescence than those with transient symptoms. Our findings suggest that the early occurrence of PLEs is an important and independent predictor of future PLEs and should be monitored to identify individuals with a high risk of future psychopathology and to enable early interventions.

Periodontitis Is Associated with Consumption of Processed and Ultra-Processed Foods: Findings from a Population-Based Study

The association between periodontitis and lifestyle factors has been widely investigated. However, an association between periodontitis and dietary patterns has not been explored. Therefore, this study investigated the association between periodontitis and food consumption among a Southern Brazil population. Data from the 1982 Pelotas Birth Cohort were used (n = 537). The exposure, periodontitis, was clinically measured and classified using the AAP/CDC system, then two latent variables were defined: ‘initial’ and ‘moderate/severe’ periodontitis. The consumption of in natura, processed, and ultra-processed foods (NOVA classification) was the outcome and measured in calories using the food frequency questionnaire (FFQ). Confounders were sex, maternal education, smoking status, xerostomia, and halitosis. Data were analyzed by structural equation modeling. ‘Initial’ periodontitis was associated with a higher consumption of in natura food (standardized coefficient (SC) 0.102; p-value = 0.040), versus processed (SC 0.078; p-value = 0.129) and ultra-processed (SC 0.043; p-value = 0.400) foods. ‘Moderate/severe’ periodontitis was associated with higher consumption of ultra-processed foods (SC 0.108; p-value = 0.024), versus processed (SC 0.093; p-value = 0.053) and in natura (SC 0.014; p-value = 0.762) foods. ‘Moderate/severe’ periodontitis appears to be associated with the consumption of processed and ultra-processed foods.

Fathers' Mental Health and Children's Aggressive Behaviour A Study Based on Data from the Norwegian Mother, Father and Child Cohort Study (MoBa)

The aim of the study was to examine the association between fathers' prenatal psychological distress and children's aggressive behaviour in terms of hitting others, and how children's age, gender and temperament affect this association. The study is based on data from 20,155 fathers and mothers from the Norwegian Mother, Father and Child Cohort Study (MoBa). Fathers and mothers completed questionnaires at 17 or 18 weeks of gestation and mothers at children's age 18 months, and 3 and 5 years. Fathers' prenatal psychological distress was assessed by the 5-item Symptom Checklist (SCL-5), and children's temperament by 12 items from the Emotionality Activity Sociability (EAS) Temperament Survey. Increasing prenatal psychological distress in fathers was associated with an increase of hitting from 18 months to 3 years of age in boys. Children's temperament did not affect the association between fathers' prenatal psychological distress and children's aggressive behaviour.

Magical thinking in individuals with high polygenic risk for schizophrenia but no non-affective psychoses-a general population study

A strong genetic background for psychoses is well-established. Most individuals with a high genetic risk for schizophrenia, however, do not develop the disorder. We investigated whether individuals, who have a high genetic risk for schizophrenia but no non-affective psychotic disorders, are predisposed to develop milder forms of deviant thinking in terms of magical thinking. Participants came from the population-based Young Finns Study (n = 1292). The polygenic risk score for schizophrenia (PRS) was calculated on the basis of the most recent genome-wide association study (GWAS). Psychiatric diagnoses over the lifespan were collected up to 2017 from the registry of hospital care. Magical thinking was evaluated with the Spiritual Acceptance Scale (e.g., beliefs in telepathy, miracles, mystical events, or sixth sense) of the Temperament and Character Inventory in 1997, 2001, and 2012 (participants were 20-50-year-olds). We found that, among those who did not develop non-affective psychotic disorders, high PRS predicted higher magical thinking in adulthood (p = 0.001). Further, PRS predicted different developmental courses: a low PRS predicted a steady decrease in magical thinking from age 20 to 50 years, while in individuals with high PRS the decrease in magical thinking ceased in middle age so that their level of magical thinking remained higher than expected for that age. These findings remained when controlling for sex, childhood family environment, and adulthood socioeconomic factors. In conclusion, if high PRS does not lead to a non-affective psychotic disorder, it predicts milder forms of deviant thinking such as elevated magical thinking in adulthood, especially in middle age. The finding enhances our understanding of different outcomes of high genetic psychosis risk.

Attrition in longitudinal studies among patients with schizophrenia and other psychoses; findings from the STRATA collaboration

A major problem with longitudinal studies is the bias generated due to attrition, particularly apparent amongst patients suffering from psychotic disorders. Factors associated with study-participation were investigated as part of a larger research collaboration (STRATA). Out of 479 eligible participants, only 50 (10,4%) were successfully followed up. The present study investigated whether study participation differed depending on baseline characteristics. Results indicated that individuals who did not participate were more likely to report an alcohol use disorder while those who did respond were more likely to have been in full-time education for longer and be of white ethnicity. Participation did not differ depending on diagnosis, symptoms, GAF, age of onset or depression.

The cross-sectional interplay between neurochemical profile and brain connectivity

Neurochemical profile and brain connectivity are both critical aspects of brain function. However, our knowledge of their interplay across development is currently poor. We combined single-voxel magnetic resonance spectroscopy and resting functional magnetic resonance imaging in a cross-sectional sample spanning from childhood to adulthood which was reassessed in ~1.5 years (N = 293). We revealed the developmental trajectories of 20 neurochemicals in two key developmental brain regions (the intraparietal sulcus, IPS, and the middle frontal gyrus, MFG). We found that certain neurochemicals exhibited similar developmental trajectories across the two regions, while other trajectories were region-specific. Crucially, we mapped the connectivity of the brain regions IPS and MFG to the rest of the brain across development as a function of regional glutamate and GABA concentration. We demonstrated that glutamate concentration within the IPS is modulated by age in explaining IPS connectivity with frontal, temporal and parietal regions. In mature participants, higher glutamate within the IPS was related to more negative connectivity while the opposite pattern was found for younger participants. Our findings offer specific developmental insights on the interplay between the brain's resting activity and the glutamatergic system both of which are crucial for regulating normal functioning and are dysregulated in several clinical conditions.

Smartphone-Based Passive Sensing for Behavioral and Physical Monitoring in Free-Life Conditions: Technical Usability Study

BACKGROUND

Smartphone use is widely spreading in society. Their embedded functions and sensors may play an important role in therapy monitoring and planning. However, the use of smartphones for intrapersonal behavioral and physical monitoring is not yet fully supported by adequate studies addressing technical reliability and acceptance.

OBJECTIVE

The objective of this paper is to identify and discuss technical issues that may impact on the wide use of smartphones as clinical monitoring tools. The focus is on the quality of the data and transparency of the acquisition process.

METHODS

QuantifyMyPerson is a platform for continuous monitoring of smartphone use and embedded sensors data. The platform consists of an app for data acquisition, a backend cloud server for data storage and processing, and a web-based dashboard for data management and visualization. The data processing aims to extract meaningful features for the description of daily life such as phone status, calls, app use, GPS, and accelerometer data. A total of health subjects installed the app on their smartphones, running it for 7 months. The acquired data were analyzed to assess impact on smartphone performance (ie, battery consumption and anomalies in functioning) and data integrity. Relevance of the selected features in describing changes in daily life was assessed through the computation of a k-nearest neighbors global anomaly score to detect days that differ from others.

RESULTS

The effectiveness of smartphone-based monitoring depends on the acceptability and interoperability of the system as user retention and data integrity are key aspects. Acceptability was confirmed by the full transparency of the app and the absence of any conflicts with daily smartphone use. The only perceived issue was the battery consumption even though the trend of battery drain with and without the app running was comparable. Regarding interoperability, the app was successfully installed and run on several Android brands. The study shows that some smartphone manufacturers implement power-saving policies not allowing continuous sensor data acquisition and impacting integrity. Data integrity was 96% on smartphones whose power-saving policies do not impact the embedded sensor management and 84% overall.

CONCLUSIONS

The main technological barriers to continuous behavioral and physical monitoring (ie, battery consumption and power-saving policies of manufacturers) may be overcome. Battery consumption increase is mainly due to GPS triangulation and may be limited, while data missing because of power-saving policies are related only to periods of nonuse of the phone since the embedded sensors are reactivated by any smartphone event. Overall, smartphone-based passive sensing is fully feasible and scalable despite the Android market fragmentation.

Understanding trajectories of externalizing problems: Stability and emergence of risk factors from infancy to middle adolescence

Despite considerable efforts to understand the processes that underlie the development of externalizing behavior problems, it is still unclear why externalizing problems remain chronically high for some children, emerge early and cease by late childhood for others, and arise in adolescence in some cases. The purpose of this study was to examine how a wide range of child and family risk factors are linked to trajectories of externalizing behavior and how these relationships vary from infancy to middle adolescence. We used data from the community-based Norwegian Tracking Opportunities and Problems (TOPP) study sample (n = 921). A Cholesky factorization model was specified to separate stable and emerging risk doses across four developmental periods (infancy, early and middle childhood, and middle adolescence). Children in the High Stable class were characterized by substantially elevated risk levels in multiple domains throughout the study period. Children in the High Childhood Limited class had very high levels of temperamental emotionality, internalizing symptoms, and maternal mental distress, suggesting a substantial intrinsic emotional basis for their externalizing problems. Intrinsic factors seemed less salient for the Adolescent Onset class. These findings emphasize the need for a dynamic perspective on risk factors and support the importance of prevention and intervention efforts across multiple domains from early childhood and throughout adolescence.

Sleep Duration Moderates the Relationship Between Perceived Work-Life Interference and Depressive Symptoms in Australian Men and Women from the North West Adelaide Health Study

BACKGROUND

Mental health disorders are prevalent and costly to workplaces and individuals in Australia. Work-life interference is thought to contribute negatively. The interplay between work-life interference, depressive symptoms and sleep has not been explored to date in population data. The aims of this study were to establish whether sleep duration moderates the relationship between work-life interference and depressive symptoms, and whether this is expressed differentially in male and female respondents.

METHODS

Data were drawn from the North West Adelaide Health Study (NWAHS) longitudinal, representative population-based cohort study. Working members of the cohort were invited to participate in a telephone survey about their work conditions, with an 86.7% response rate achieved. Data from 823 respondents were analysed after employing purposeful selection of covariates, using multivariable regression analysis.

RESULTS

Sleep duration was found to moderate the relationship between work-life interference and depressive symptoms (F_7,815 = 26.60, p < 0.001), and accounted for 19% of the variance observed in depressive symptoms. The strongest effect of work-life interference on depressive symptoms was observed in habitual short sleepers, with the effect weakening as sleep duration increased. The relationship was observed in male and female respondents, but was stronger in females.

CONCLUSIONS

Supporting and educating workers about the benefits of sleep for managing the relationship between work-life interference and depressive symptoms may offer a novel strategy for improving worker well-being, particularly when negative facets of work-life interference are not easily remedied or 'reduced'. There is a need for education and support strategies around sleep in Australian workplaces.

Mediating role of disordered eating in the relationship between screen time and BMI in adolescents: longitudinal findings from the Research on Eating and Adolescent Lifestyles (REAL) study

OBJECTIVE

This study investigated whether the duration and type of screen time (ST) (TV viewing, recreational computer use, video gaming) is longitudinally associated with z-BMI and if these relationships are mediated by disordered eating (emotional, restrained).

DESIGN

At baseline, participants were n 1197 (T1; 60 % female) adolescents (mean age = 13·51 years) who completed surveys over 2 years. ST was assessed by a self-reported measure created by the investigative team, while emotional and restrained eating was measured by the Dutch Eating Behaviour Questionnaire (DEB-Q). Height and weight were objectively measured to quantify z-BMI.

SETTING

Thirty-one public and two private schools from the region of Ottawa, Canada.

PARTICIPANTS

Students in grades 7-12.

RESULTS

Parallel multiple mediation analyses revealed that more time spent watching TV at baseline is associated with higher z-BMI at T3 (total effect; B = 0·19, se = 0·07, P = 0·01, 95 % CI 0·05, 0·34), but no relationships were observed for total ST exposure or other types of ST and z-BMI. Disordered eating did not mediate the positive association between baseline TV viewing and z-BMI at T3.

CONCLUSIONS

TV viewing was longitudinally associated with higher z-BMI in a community-based sample of adolescents, but disordered eating behaviours did not mediate this relationship. However, other non-pathological eating behaviours may mediate the association between ST and obesity and warrant further investigation. Finding suggests that targeting reduction in youth's TV viewing may be an effective component in the prevention of childhood obesity.

How important are parents in the development of child anxiety and depression? A genomic analysis of parent-offspring trios in the Norwegian Mother Father and Child Cohort Study (MoBa)

BACKGROUND

Many studies detect associations between parent behaviour and child symptoms of anxiety and depression. Despite knowledge that anxiety and depression are influenced by a complex interplay of genetic and environmental risk factors, most studies do not account for shared familial genetic risk. Quantitative genetic designs provide a means of controlling for shared genetics, but rely on observed putative exposure variables, and require data from highly specific family structures.

METHODS

The intergenerational genomic method, Relatedness Disequilibrium Regression (RDR), indexes environmental effects of parents on child traits using measured genotypes. RDR estimates how much the parent genome influences the child indirectly via the environment, over and above effects of genetic factors acting directly in the child. This 'genetic nurture' effect is agnostic to parent phenotype and captures unmeasured heritable parent behaviours. We applied RDR in a sample of 11,598 parent-offspring trios from the Norwegian Mother, Father and Child Cohort Study (MoBa) to estimate parental genetic nurture separately from direct child genetic effects on anxiety and depression symptoms at age 8. We tested for mediation of genetic nurture via maternal anxiety and depression symptoms. Results were compared to a complementary non-genomic pedigree model.

RESULTS

Parental genetic nurture explained 14% of the variance in depression symptoms at age 8. Subsequent analyses suggested that maternal anxiety and depression partially mediated this effect. The genetic nurture effect was mirrored by the finding of family environmental influence in our pedigree model. In contrast, variance in anxiety symptoms was not significantly influenced by common genetic variation in children or parents, despite a moderate pedigree heritability.

CONCLUSIONS

Genomic methods like RDR represent new opportunities for genetically sensitive family research on complex human traits, which until now has been largely confined to adoption, twin and other pedigree designs. Our results are relevant to debates about the role of parents in the development of anxiety and depression in children, and possibly where to intervene to reduce problems.

School Climate as an Intervention to Reduce Academic Failure and Educate the Whole Child: A Longitudinal Study

BACKGROUND

Preventing student academic failure is crucial to student health and life success. Previous studies suggest a positive school climate may reduce students' risk for academic failure and contribute to academic success. The purpose of this study was to determine the longitudinal associations between school climate and academic grades in a group of middle school students who transition into high school.

METHODS

Parallel latent growth curve modeling was used to examine changes among study variables longitudinally using a sample of 2604 in 6th, 7th, and 8th-grade students across 16 regional schools located in 3 counties in West Virginia.

RESULTS

Students with higher perceptions of a positive school climate exhibited sustained or improved academic achievement over time (β = 0.22 to 0.30, p < .01). Higher positive perceptions of school climate appear to sustain students who earn As/Bs (β = 0.20 to 0.27, p < .01) and strengthen students who earn Cs/Ds/Fs (β = -0.16 to -0.46, p < .05).

CONCLUSIONS

Positive student perceptions of school climate may sustain high academic performance while strengthening students who earn Cs/Ds/Fs. School climate may be useful as an intervention to support school-based health promotion to reduce the achievement gap in the United States.

The Barcelona Brain Health Initiative: Cohort description and first follow-up

The Barcelona Brain Health Initiative is a longitudinal cohort study that began in 2017 and aims to understand and characterize the determinants of brain health maintenance in middle aged adults. A cohort of 4686 individuals between the ages of 40 and 65 years free from any neurological or psychiatric diseases was established, and we collected extensive demographic, socio-economic information along with measures of self-perceived health and lifestyles (general health, physical activity, cognitive activity, socialization, sleep, nutrition and vital plan). Here we report on the baseline characteristics of the participants, and the results of the one-year follow-up evaluation. Participants were mainly women, highly educated, and with better lifestyles compared with the general population. After one year 60% of participants completed the one-year follow-up, and these were older, with higher educational level and with better lifestyles in some domains. In the absence of any specific interventions to-date, these participants showed small improvements in physical activity and sleep, but decreased adherence to a Mediterranean diet. These changes were negatively associated with baseline scores, and poorer habits at baseline were predictive of an improvement in lifestyle domains. Of the 2353 participants who completed the one-year follow-up, 73 had been diagnosed with new neurological and neuropsychiatric diseases. Changes in vital plan at follow-up, as well as gender, sleep quality and sense of coherence at baseline were shown to be significant risk factors for the onset of these diagnoses. Notably, gender risk factor decreased in importance as we adjusted by sleep habits, suggesting its potential mediator effects. These findings stress the importance of healthy lifestyles in sustaining brain health, and illustrate the individual benefit that can be derived from participation in longitudinal observational studies. Modifiable lifestyles, specifically quality of sleep, may partially mediate the effect of other risk factors in the development of some neuropsychiatric conditions.

Mental disorders, attrition at follow-up, and questionnaire non-completion in epidemiologic research. Illustrations from the CoLaus|PsyCoLaus study

OBJECTIVE

This study aimed to investigate the associations between mental disorders recorded at baseline and participation in the subsequent follow-up interview (vs. attrition) or baseline questionnaire completion (vs. non-response) within the psychiatric arm of a population-based study.

METHODS

Participants of a physical health survey were initially invited to also participate in a semi-structured interview covering mental disorders and were reassessed approximately 5.5 years later. They were also asked to complete self-rating questionnaires at baseline. Associations between the presence of lifetime mental disorders assessed at baseline and attrition at follow-up as well as non-completion of self-rating questionnaires at baseline were established.

RESULTS

After controlling for sociodemographic variables, a significant negative association was found between anxiety disorders at baseline and attrition at follow-up (Adjusted odds ratio (AOR) = 0.84; 95% confidence interval (CI) = 0.71-1.00) and a positive association between major depressive disorders (MDD) and non-response to the self-rating questionnaires at baseline (AOR = 1.24; 95% CI = 1.05-1.45).

CONCLUSIONS

The associations of anxiety disorders during lifetime with a higher participation rate in interviews at follow-up and of MDD during lifetime with the non-completion of self-rating questionnaires are potential sources of bias and should be taken into account in future longitudinal research.

Online Delivery of Emotional Freedom Techniques for Food Cravings and Weight Management: 2-Year Follow-Up

Background: Growing obesity rates are a problem worldwide. Several studies of emotional freedom techniques (EFT), a brief psychophysiologic technique, have indicated that it may be a promising addition to traditional weight loss interventions. Objective: The current study evaluated food cravings, dietary restraint, subjective power of food, weight changes, and self-reported symptoms (e.g., somatic, anxious, and depressive) 2 years after an 8-week online self-directed EFT intervention with additional online support. Design: Participants were initially randomly allocated to a treatment or waitlist group. The treatment group was instructed to self-pace through an online EFT treatment program made up of seven modules throughout the 8-week intervention period, and the waitlist was also completed at the end of this period. Results: Analyses of the online EFT intervention program indicated significantly reduced scores for food cravings (-28.2%), power of food (-26.7%), depression (-12.3%), anxiety (-23.3%), and somatic symptoms (-10.6%) from pre to postintervention and from pre (baseline) until the 2-year follow-up and significantly improved scores for restraint (+13.4%). Further improvements were experienced for carbohydrates and fast food cravings between 6 months and 2 years. Body Mass Index and weight significantly decreased from pre- to 12 months follow-up although there were no differences at the 2-year point. Conclusions: As an online intervention program, EFT was very effective in reducing food cravings, perceived power of food, psychologic symptomatology, and improving dietary restraint and maintaining those improvements over a 2-year period. The addition of EFT to traditional weight loss interventions is timely and supported by this research.

Joint factorial structure of psychopathology and personality

BACKGROUND

Normative and pathological personality traits have rarely been integrated into a joint large-scale structural analysis with psychiatric disorders, although a recent study suggested they entail a common individual differences continuum.

METHODS

We explored the joint factor structure of 11 psychiatric disorders, five personality-disorder trait domains (DSM-5 Section III), and five normative personality trait domains (the 'Big Five') in a population-based sample of 2796 Norwegian twins, aged 19‒46.

RESULTS

Three factors could be interpreted: (i) a general risk factor for all psychopathology, (ii) a risk factor specific to internalizing disorders and traits, and (iii) a risk factor specific to externalizing disorders and traits. Heritability estimates for the three risk factor scores were 48% (95% CI 41‒54%), 35% (CI 28‒42%), and 37% (CI 31‒44%), respectively. All 11 disorders had uniform loadings on the general factor (congruence coefficient of 0.991 with uniformity). Ignoring sign and excluding the openness trait, this uniformity of factor loadings held for all the personality trait domains and all disorders (congruence 0.983).

CONCLUSIONS

Based on our findings, future research should investigate joint etiologic and transdiagnostic models for normative and pathological personality and other psychopathology.

Preventing bias from selective non-response in population-based survey studies: findings from a Monte Carlo simulation study

Background

Health researchers often use survey studies to examine associations between risk factors at one time point and health outcomes later in life. Previous studies have shown that missing not at random (MNAR) may produce biased estimates in such studies. Medical researchers typically do not employ statistical methods for treating MNAR. Hence, there is a need to increase knowledge about how to prevent occurrence of such bias in the first place.

Methods

Monte Carlo simulations were used to examine the degree to which selective non-response leads to biased estimates of associations between risk factors and health outcomes when persons with the highest levels of health problems are under-represented or totally missing from the sample. This was examined under different response rates and different degrees of dependency between non-response and study variables.

Results

Response rate per se had little effect on bias. When extreme values on the health outcome were completely missing, rather than under-represented, results were heavily biased even at a 70% response rate. In most situations, 50–100% of this bias could be prevented by including some persons with extreme scores on the health outcome in the sample, even when these persons were under-represented. When some extreme scores were present, estimates of associations were unbiased in several situations, only mildly biased in other situations, and became biased only when non-response was related to both risk factor and health outcome to substantial degrees.

Conclusions

The potential for preventing bias by including some extreme scorers in the sample is high (50–100% in many scenarios). Estimates may then be relatively unbiased in many situations, also at low response rates. Hence, researchers should prioritize to spend their resources on recruiting and retaining at least some individuals with extreme levels of health problems, rather than to obtain very high response rates from people who typically respond to survey studies. This may contribute to preventing bias due to selective non-response in longitudinal studies of risk factors and health outcomes.

The structure of genetic and environmental influences on normative personality, abnormal personality traits, and personality disorder symptoms

BACKGROUND

Can the structure of genetic and environmental influences on normative personality traits (NPTs), abnormal personality traits (APTs), and DSM-IV criteria for personality disorders (PD) fit a high or low congruence model positing, respectively, close or more limited etiologic continuity?

METHOD

Exploratory factor analysis was applied to transformed correlation matrices from Cholesky twin decompositions obtained in OpenMx. In 2801 adult twins from the Norwegian Institute of Public Health Twin Panel, NPTs and APTs were assessed by self-report using the Big Five Inventory (BFI) and PID-5-Norwegian Brief Form (PID-5-NBF), respectively. PDs were assessed at interview using the Structured Interview for DSM-IV Personality (SIDP-IV).

RESULTS

The best model yielded three genetic and three unique environmental factors. Genetic factors were dominated, respectively, by (i) high loadings on nearly all PDs and NPT/APT neuroticism and compulsivity, (ii) negative loadings on NPT agreeableness/conscientiousness and positive loadings on APT/PD measures of antisocial traits, and (iii) negative loadings on NPT extraversion and histrionic PD, and positive loadings on APT detachment and schizoid/avoidant PD. Unique environmental factors were dominated, by (i) high loadings on all PDs, (ii) high loadings on all APT dimensions and NPT neuroticism, and (iii) negative loadings on NPT extraversion and positive loadings on NPT detachment/avoidant PD.

CONCLUSIONS

Two genetic and one environmental common factor were consistent with a high congruence model while one genetic and two environmental factors were more supportive of a low congruence model. The relationship between genetic and environmental influences on personality assessed by NPTs, APTs, and PDs is complex and does not fit easily into a low or high congruence model.

Relationships Among Avoidant Personality Disorder, Social Anxiety Disorder, and Normative Personality Traits: A Twin Study

Avoidant personality disorder (AvPD) and social anxiety disorder (SAD) share risk factors to a substantial degree, and both are characterized by the experience of anxiety in social situations. The authors investigated whether these disorders are differentially related to the Big Five personality traits. They also examined the underlying genetic and environmental influences on these associations. A population-based sample of 1,761 female twins was interviewed at baseline, and 1,471 of these were re-interviewed 10 years later. Associations between AvPD, SAD, and personality traits were investigated with multivariate biometric analyses. The authors found that AvPD and SAD are differentially related to several personality traits at the phenotypic, genetic, and environmental level. The genetic and environmental liability to AvPD could be fully accounted for by the genetic and environmental factors influencing SAD and personality. The findings may increase current etiological understanding of these disorders and inform future classification and treatment efforts.

Explaining the association between anxiety disorders and alcohol use disorder: A twin study

BACKGROUND

It is unknown whether social anxiety disorder (SAD) has a unique association with alcohol use disorder (AUD) over and beyond that of other anxiety disorders, how the associations develop over time, and whether the associations are likely to be causal.

METHODS

Diagnoses of AUD, SAD, generalized anxiety disorder, panic disorder, agoraphobia, and specific phobias were assessed twice using the Composite International Diagnostic Interview among 2,801 adult Norwegian twins. The data were analyzed using logistic regression analyses and multivariate biometric structural equation modeling.

RESULTS

SAD had the strongest association with AUD, and SAD predicted AUD over and above the effect of other anxiety disorders. In addition, SAD was prospectively associated with AUD, whereas other anxiety disorders were not. AUD was associated with a slightly elevated risk of later anxiety disorders other than SAD. Biometric modeling favored a model where SAD influenced AUD compared to models where the relationship was reversed or due to correlated risk factors. Positive associations between AUD and other anxiety disorders were fully explained by shared genetic risk factors.

CONCLUSIONS

Unlike other anxiety disorders, SAD plausibly has a direct effect on AUD. Interventions aimed at prevention or treatment of SAD may have an additional beneficial effect of preventing AUD, whereas interventions aimed at other anxiety disorders are unlikely to have a similar sequential effect on AUD.

Genetically Informative Mediation Modeling Applied to Stressors and Personality-Disorder Traits in Etiology of Alcohol Use Disorder

A statistical mediation model was developed within a twin design to investigate the etiology of alcohol use disorder (AUD). Unlike conventional statistical mediation models, this biometric mediation model can detect unobserved confounding. Using a sample of 1410 pairs of Norwegian twins, we investigated specific hypotheses that DSM-IV personality-disorder (PD) traits mediate effects of childhood stressful life events (SLEs) on AUD, and that adulthood SLEs mediate effects of PDs on AUD. Models including borderline PD traits indicated unobserved confounding in phenotypic path coefficients, whereas models including antisocial and impulsive traits did not. More than half of the observed effects of childhood SLEs on adulthood AUD were mediated by adulthood antisocial and impulsive traits. Effects of PD traits on AUD 5‒10 years later were direct rather than mediated by adulthood SLEs. The results and the general approach contribute to triangulation of developmental origins for complex behavioral disorders.

Testing Genetic and Environmental Associations Between Personality Disorders and Cocaine Use: A Population-Based Twin Study

Until now, data have not been available to elucidate the genetic and environmental sources of comorbidity between all 10 DSM-IV personality disorders (PDs) and cocaine use. Our aim was to determine which PD traits are linked phenotypically and genetically to cocaine use. Cross-sectional data were obtained in a face-to-face interview between 1999 and 2004. Subjects were 1,419 twins (µage = 28.2 years, range = 19-36) from the Norwegian Institute of Public Health Twin Panel, with complete lifetime cocaine use and criteria for all 10 DSM-IV PDs. Stepwise multiple and Least Absolute Shrinkage and Selection Operator (LASSO) regressions were used to identify PDs related to cocaine use. Twin models were fitted to estimate genetic and environmental associations between the PD traits and cocaine use. In the multiple regression, antisocial (OR = 4.24, 95% CI [2.66, 6.86]) and borderline (OR = 2.19, 95% CI [1.35, 3.57]) PD traits were significant predictors of cocaine use. In the LASSO regression, antisocial, borderline, and histrionic were significant predictors of cocaine use. Antisocial and borderline PD traits each explained 72% and 25% of the total genetic risks in cocaine use, respectively. Genetic risks in histrionic PD were not significantly related to cocaine use. Importantly, after removing criteria referencing substance use, antisocial PD explained 65% of the total genetic variance in cocaine use, whereas borderline explained only 4%. Among PD traits, antisocial is the strongest correlate of cocaine use, for which the association is driven largely by common genetic risks.

Associations between personality disorders and cannabis use and cannabis use disorder: a population-based twin study

BACKGROUND AND AIMS

Individual differences in DSM-IV personality disorders (PDs) are associated with increased prevalence of substance use disorders. Our aims were to determine which combination of PDs trait scores best predict cannabis use (CU) and cannabis use disorder (CUD), and to estimate the size and significance of genetic and environmental risks in PD traits shared with CU and CUD.

DESIGN

Linear mixed-effects models were used to identify PD traits for inclusion in twin analyses to explore the genetic and environmental associations between the traits and cannabis use.

SETTING

Cross-sectional data were obtained from Norwegian adult twins in a face-to-face interview in 1999-2004 as part of a population-based study of mental health.

PARTICIPANTS

Subjects were 1419 twins (μage  = 28.2 years, range = 19-36) from the Norwegian Institute of Public Health Twin Panel with complete PD and cannabis data.

MEASUREMENTS

PD traits were assessed using DSM-IV criteria. Life-time CU and CUD were based on DSM-IV abuse and dependence criteria, including withdrawal and craving.

FINDINGS

After adjusting for age and sex, antisocial [β = 0.23, 95% confidence interval (CI) = 0.19-0.28] and borderline PDs (β = 0.20, 95% CI = 0.14-0.26) were associated strongly with CU. Antisocial (β = 0.26, 95% CI = 0.21-0.31) and borderline PDs (β = 0.12, 95% CI = 0.06-0.18) were also linked strongly to CUD. Genetic risks in antisocial and borderline PD traits explained 32-60% of the total variance in CU and CUD. Dependent and avoidant PDs explained 11 and 16% of the total variance in CU and CUD, respectively.

CONCLUSIONS

Individual differences in the liability to cannabis use and cannabis use disorder appear to be linked to genetic risks correlated with antisocial and borderline personality disorder traits.

Prevalence and stability of mental disorders among young adults: findings from a longitudinal study

BACKGROUND

Mental disorders often have onset early in life, contribute substantially to the global disease burden, and may interfere with young people's ability to complete age-relevant tasks in important developmental periods. However, knowledge about prevalence and course of mental disorders in young adulthood is sparse. The aim of the current study was to estimate prevalence and stability of mental disorders from the twenties to the thirties/forties.

METHODS

DSM-IV mental disorders were assessed with the Composite International Diagnostic Interview in two waves (1999-2004 and 2010-2011) in 1623 young adult Norwegian twins (63.2% women, aged 19-29 years in wave 1).

RESULTS

In wave 1, the 12-month prevalence of any mental disorder among people in the twenties was 19.8% (men) and 32.4% (women), anxiety disorders: 9.6% (men) and 26.7% (women), anxiety disorders excluding specific phobias: 2.5% (men) and 6.9% (women), major depressive disorder (MDD): 4.4% (men) and 7.2% (women), and alcohol use disorder (AUD): 8.7% (men) and 4.4% (women). The prevalence of any mental disorder decreased from the twenties to the thirties/forties. This was due to a decrease in AUD and specific phobias. Anxiety disorders in the twenties predicted anxiety disorders and MDD ten years later, even when controlling for the association between these disorders in the twenties. MDD in the twenties predicted MDD ten years later. At both ages, two-week and 12-month prevalence estimates differed markedly for MDD - indicating an episodic course.

CONCLUSIONS

Common mental disorders are highly prevalent among young adults in the twenties, and somewhat less prevalent in the thirties/forties. Those who suffer from one mental disorder in the twenties are at considerably increased risk for suffering from a disorder ten years later as well. This may have significant implications for young people's ability to attain education, establish a family, and participate in occupational life.

Diagnostic and genetic overlap of three common mental disorders in structured interviews and health registries

OBJECTIVE

To investigate whether diagnostic data from structured interviews, primary care and specialist care registries on major depressive disorder (MDD), anxiety disorders (AD) and alcohol use disorder (AUD) identify the same individuals, yield comparable comorbidity estimates and reflect the same genetic influences.

METHODS

Registry data from primary and specialist care were available for 11 727 twins and diagnostic interview data for 2271 of these. We used logistic regression analyses and biometric modelling to investigate the overlap between the data sources.

RESULTS

Most individuals meeting diagnostic criteria at interview were not registered with a corresponding diagnosis. The rates of registration were higher for MDD (36% in primary care and 15% in specialist care) and AD (21% and 18%) than for AUD (3% and 7%). Comorbidity estimated as odds ratios, but not as polychoric correlations, was higher in the registries than in the interviews. Genetic influences on the disorders were highly correlated across data sources (median r = 0.81), bordering unity for MDD and AD.

CONCLUSION

Prevalence and comorbidity estimates differ between registries and population-based assessment. Nevertheless, diagnoses from health registries reflect the same genetic influences as common mental disorders assessed in the general population, indicating generalizability of aetiological factors across data sources.

Prediction of alcohol use disorder using personality disorder traits: a twin study

BACKGROUND AND AIMS

The DSM-IV personality disorders (PDs) are comorbid with alcohol use disorder (AUD) and with each other. It remains unclear which PD criteria are most likely to drive onset and recurrence of AUD and which are merely confounded with those criteria. We determine which individual PD criteria predict AUD and the degree of underlying genetic and/or environmental aetiology.

DESIGN

A prospective observational twin study.

SETTING

Norway 1999-2011.

PARTICIPANTS

A total of 2528 and 2275 Norwegian adult twins in waves 1 and 2 variable-selection analyses, and 2785 in biometric analyses.

MEASUREMENTS

DSM-IV PDs and their 80 criteria were assessed using a structured personal interview, and AUD using the World Health Organization's Composite International Diagnostic Interview.

FINDINGS

In a variable-selection analysis, two PD criteria were associated with AUD even after taking all the other criteria into account: criterion 8 of antisocial PD (childhood conduct disorder) and criterion 4 of borderline PD (self-damaging impulsive behaviours). Adjusting for each other, their respective odds ratios were 3.4 [confidence interval (CI) = 2.1-5.4] and 5.0 (CI = 3.3-7.7). Endorsement strength of the criteria was associated with AUD in a dose-response manner and they explained 5.5% of variation in AUD risk-more than the full diagnoses of antisocial and borderline PDs together (0.5%). The association between borderline criterion 4 and AUD 10 years later derived mainly from their overlapping genetic factors, whereas the association between antisocial criterion 8 and AUD 10 years later was due to both genetic and non-genetic factors.

CONCLUSIONS

Conduct disorder and self-harming impulsivity are the foremost risk traits for alcohol use disorder among the 80 personality disorder criteria of DSM-IV, predicting alcohol use disorder more effectively than personality disorder diagnoses. The twin-study analysis suggested that conduct disorder represents a joint genetic and developmental risk for alcohol use disorder and that impulsivity is a genetic risk.

An investigation of the process of change in psychopathology and exercise during inpatient treatment for adults with longstanding eating disorders

BACKGROUND

Excessive exercise is recognized as a predictor of poor outcome in eating disorders. However, little is known about how excessive exercise might affect the treatment process. The aim of this study was to describe process of weekly changes in eating disorder psychopathology, general psychopathology and exercise, and the possible interactive effects of excessive exercise on these changes during inpatient treatment of longstanding eating disorders.

METHODS

Eighty-four patients meeting the DSM-IV criteria for Anorexia Nervosa, Bulimia Nervosa, or Eating Disorders Not Otherwise Specified received inpatient cognitive-behavioural therapy including, physical activity and nutritional counselling treatment over 12 weeks. Excessive exercise was defined as having ≥6 episodes of driven exercise during week 1 of treatment. Excessive exercisers received one additional session of individual counseling with the clinical exercise physiologist. The study used repeated measurements during treatment and collected measures of eating disorders: psychopathology (EDE-Q), general psychopathology (SCL-5), and frequencies of exercise and body mass index (BMI). Statistical analysis was performed using repeated measures ANOVA.

RESULTS

Both eating disorders and general psychopathology were reduced from admission to discharge in excessive exercisers and non-exercisers. There was an overall interaction effect between time (week) and excessive exercise for the process of exercise and eating disorders psychopathology reduction. This interaction effect was also found in week 10 vs 11 regarding general psychopathology. The excessive exercisers showed steep reduction at first, followed by a smaller increase towards the end of treatment in both eating disorder and general psychopathology; this pattern was not found among the non-exercisers.

CONCLUSION

The process of change in exercise and psychopathology during inpatient treatment of longstanding eating disorders differs across excessive and non-excessive exercisers. Although excessive exercisers were given special attention for their exercise cognition and behavior during treatment, it is apparent that this part of treatment must be further developed.

Genetic and Environmental Contributions to the Association Between Cannabis Use and Psychotic-Like Experiences in Young Adult Twins

To investigate contributions of genetic and environmental risk factors and possible direction of causation for the relationship between symptoms of cannabis use disorders (CUD) and psychotic-like experiences (PLEs), a population-based sample of 2793 young adult twins (63.5% female, mean [range] age 28.2 [19-36] y) were assessed for symptoms of CUD and PLEs using the Composite International Diagnostic Interview. Latent risk of having symptoms of CUD or PLEs was modeled using Item Response Theory. Co-twin control analysis was performed to investigate effect of familiar confounding for the association between symptoms of CUD and PLEs. Biometric twin models were fitted to estimate the heritability, genetic and environmental correlations, and direction for the association. Lifetime use of cannabis was reported by 10.4 % of the twins, and prevalence of PLEs ranged from 0.1% to 2.2%. The incidence rate ratio of PLEs due to symptoms of CUD was 6.3 (95% CI, 3.9, 10.2) in the total sample and 3.5 (95% CI, 1.5, 8.2) within twin pairs. Heritability estimates for symptoms of CUD were 88% in men and women, and for PLEs 77% in men and 43% in women. The genetic and environmental correlations between symptoms of CUD and PLEs were 0.55 and 0.52, respectively. The model allowing symptoms of CUD to cause PLEs had a better fit than models specifying opposite or reciprocal directions of causation. The association between symptoms of CUD and PLEs is explained by shared genetic and environmental factors and direct effects from CUD to risk for PLEs.

The association between personality disorders with alcohol use and misuse: A population-based twin study

BACKGROUND

A clearer understanding of the etiological overlap between DSM-IV personality disorders (PDs) and alcohol use (AU) and alcohol use disorder (AUD) is needed. To our knowledge, no study has modeled the association between all 10 DSM-IV PDs and lifetime AU and AUD. The aim of the present study is to identify which PDs are most strongly associated with the phenotypic, genetic, and environmental risks of lifetime AU and AUD, and to determine if these associations are stable across time.

METHODS

Participants were Norwegian twins assessed at two waves. At Wave 1, 2801 twins were assessed for all 10 DSM-IV PD criteria, lifetime AU, and DSM-IV AUD criteria. At Wave 2, six of the 10 PDs were again assessed along with AU and AUD among 2393 twins. Univariate and multiple logistic regressions were run. Significant predictors were further analyzed using bivariate twin Cholesky decompositions.

RESULTS

Borderline and antisocial PD criteria were the strongest predictors of AU and AUD across the two waves. Despite moderate phenotypic and genetic correlations, genetic variation in these PD criteria explained only 4% and 3% of the risks in AU, and 5% to 10% of the risks in AUD criteria, respectively. At Wave 2, these estimates increased to 8% and 23% for AU, and 17% and 33% for AUD.

CONCLUSIONS

Among a large Norwegian twin sample, borderline and antisocial PD criteria were the strongest predictors of the phenotypic and genotypic liability to AU and AUD. This effect remained consistent across time.

The Genetic and Environmental Sources of Resemblance Between Normative Personality and Personality Disorder Traits

Recent work has suggested a high level of congruence between normative personality, most typically represented by the "big five" factors, and abnormal personality traits. In 2,293 Norwegian adult twins ascertained from a population-based registry, the authors evaluated the degree of sharing of genetic and environmental influences on normative personality, assessed by the Big Five Inventory (BFI), and personality disorder traits (PDTs), assessed by the Personality Inventory for DSM-5-Norwegian Brief Form (PID-5-NBF). For four of the five BFI dimensions, the strongest genetic correlation was observed with the expected PID-5-NBF dimension (e.g., neuroticism with negative affectivity [+], conscientiousness with disinhibition [-]). However, neuroticism, conscientiousness, and agreeableness had substantial genetic correlations with other PID-5-NBF dimensions (e.g., neuroticism with compulsivity [+], agreeableness with detachment [-]). Openness had no substantial genetic correlations with any PID-5-NBF dimension. The proportion of genetic risk factors shared in aggregate between the BFI traits and the PID-5-NBF dimensions was quite high for conscientiousness and neuroticism, relatively robust for extraversion and agreeableness, but quite low for openness. Of the six PID-5-NBF dimensions, three (negative affectivity, detachment, and disinhibition) shared, in aggregate, most of their genetic risk factors with normative personality traits. Genetic factors underlying psychoticism, antagonism, and compulsivity were shared to a lesser extent, suggesting that they are influenced by etiological factors not well indexed by the BFI.

Genetic and Environmental Structure of DSM-IV Criteria for Antisocial Personality Disorder: A Twin Study

Results from previous studies on DSM-IV and DSM-5 Antisocial Personality Disorder (ASPD) have suggested that the construct is etiologically multidimensional. To our knowledge, however, the structure of genetic and environmental influences in ASPD has not been examined using an appropriate range of biometric models and diagnostic interviews. The 7 ASPD criteria (section A) were assessed in a population-based sample of 2794 Norwegian twins by a structured interview for DSM-IV personality disorders. Exploratory analyses were conducted at the phenotypic level. Multivariate biometric models, including both independent and common pathways, were compared. A single phenotypic factor was found, and the best-fitting biometric model was a single-factor common pathway model, with common-factor heritability of 51% (95% CI 40-67%). In other words, both genetic and environmental correlations between the ASPD criteria could be accounted for by a single common latent variable. The findings support the validity of ASPD as a unidimensional diagnostic construct.

Hyperemesis gravidarum and the risk of emotional distress during and after pregnancy

Hyperemesis gravidarum (HG) is a pregnancy condition characterised by severe nausea and vomiting. Previous studies have shown an association between HG and depressive symptoms during pregnancy, but little is known about the risk of maternal psychological distress following an HG pregnancy. The objective of the current study was therefore to assess the association between HG and emotional distress during and after pregnancy. This was a population-based pregnancy cohort study using data from the Norwegian Mother and Child Cohort Study. A total of 851/92,947 (0.9%) had HG. Emotional distress was measured by the Hopkins Symptom Checklist (SCL-5) in gestational weeks 17 and 32 and 6 and 18 months postpartum. The generalised estimating equations model was estimated for assessing time trends in emotional distress. Adjustments were made for previous HG, lifetime history of depression, maternal age, parity, BMI, smoking before pregnancy, physical activity, length of education, and pelvic girdle pain. Women with HG had higher odds for emotional distress than women without HG at the 17th (p < 0.001) and 32nd gestational weeks (p = 0.001) in addition to 6 months postpartum (p = 0.005) but not 18 months postpartum (p = 0.430). Adjusted odds for emotional distress varied significantly over time for women with and without HG (p = 0.035). Women with HG were more likely to report emotional distress compared to women without HG during pregnancy and 6 months postpartum, but the difference between the groups disappeared 18 months after birth. The results suggest that the increased risk of developing emotional distress may primarily be a consequence of HG.

Predicting Well-Being and Internalizing Symptoms in Late Adolescence From Trajectories of Externalizing Behavior Starting in Infancy

This study aimed to examine the long-term prediction of well-being and internalizing symptoms from trajectories of externalizing behavior problems in 921 children from a population-based sample. We found that a high stable trajectory of externalizing behavior from infancy (age 1.5) to mid-adolescence (age 14.5) predicted lower scores on life satisfaction and flourishing for both girls and boys (age 18.5). The high stable trajectory also predicted higher levels of depressive symptoms in boys and anxiety symptoms in girls (age 18.5). The findings are noteworthy as they document how a person-oriented study of externalizing behavior problems starting in infancy can predict well-being and internalizing in late adolescence. The findings underline the importance of early health promotion and problem intervention efforts.

Does low alcohol use increase the risk of sickness absence? A discordant twin study

Background

Results from observational studies suggest that people who drink little or no alcohol are less healthy than medium drinkers. This has been demonstrated for many different measures of health, including sick leave. However, whether these associations are causal or due to confounding remains to be clarified. The aim of this study was to use a discordant twin design to determine whether the increased level of sick leave associated with a low level of alcohol consumption, as compared to those with a medium level of consumption, reflects a causal mechanism or is due to genetic or environmental confounding.

Methods

Six thousand seven hundred thirty-four young adult twins from the Norwegian Institute of Public Health’s twin panel were in 1998 assessed for frequency of alcohol use and binge drinking. Data were linked to the Norwegian National Insurance Administration’s recordings of sick leave over a 10 year period. The associations between alcohol consumption and sick leave were first estimated in the total study population, and then within di- and monozygotic twin pairs discordant for alcohol use.

Results

Compared to medium consumption, both low and high alcohol consumption was associated with increased risk of sick leave. When low level drinkers were compared to medium level drinkers in a discordant twin design, the results were consistent with the association being due to genetic confounding rather than a causal effect.

Conclusions

The increased level of sick leave observed with low level drinkers seems to be mainly explained by confounding from genetic factors. In all observational studies of the relationship between alcohol consumption and health, one should be aware that important genetic confounders are likely to influence the results.

A 2-year longitudinal study of prospective predictors of pathological Internet use in adolescents

Longitudinal studies of prospective predictors for pathological Internet use (PIU) in adolescents as well as its course are lacking. This three-wave longitudinal study was conducted within the framework of the European Union-funded project "Saving and Empowering Young Lives in Europe" over a 2-year period. The sample consisted of 1444 students at the baseline investigation (T0); 1202 students after 1 year (T1); and 515 students after 2 years (T2). Structured self-report questionnaires were administered at all three time points. PIU was assessed using the Young Diagnostic Questionnaire (YDQ). In addition, demographic (i.e., gender), social (i.e., parental involvement), psychological (i.e., emotional problems), and Internet use-related factors (i.e., online activities) were assessed as prospective predictors. The prevalence of PIU was 4.3 % at T0, 2.7 % at T1 and 3.1 % at T2. However, only 3 students (0.58 %) had persistent categorical PIU (YDQ score of ≥5) over the 2-year period. In univariate models, a variety of variables that have been previously identified in cross-sectional investigations predicted PIU at T2. However, multivariate regression demonstrated that only previous PIU symptoms and emotional problems were significant predictors of PIU 2 years later (adjusted R (2) 0.23). The stability of categorical PIU in adolescents over 2 years was lower than previously reported. However, current PIU symptoms were the best predictor of later PIU; emotional symptoms also predicted PIU over and above the influence of previous problematic Internet use. Both PIU symptoms and emotional problems may contribute to the vicious cycle that supports the perpetuation of PIU.

A population-based study of help seeking and self-medication among trauma-exposed individuals

Epidemiologic studies of trauma highlight the imbalance between prevalence of psychiatric diagnoses and help seeking. We investigated prevalence and correlates of help seeking and self-medication in Norwegian adults with trauma history with a focus on common posttrauma outcomes of posttraumatic stress disorder (PTSD) and substance use disorders (alcohol or drug). Participants reporting at least 1 PTSD symptom (n = 307) were asked if they consulted with a doctor/another professional (help seeking) or used drugs/alcohol (self-medication) for trauma-related problems. PTSD, alcohol abuse or dependence (AUD), and drug use or dependence (DUD) were assessed via structured diagnostic interviews. Help seeking and self-medication were endorsed by 37.4% and 10.4% of the sample, respectively. As compared to the full sample, help seeking was endorsed at a greater rate in individuals with PTSD (χ2 = 8.59, p = .005) and at a lower rate in those with AUD (χ2 = 7.34, p < .004). Self-medication was more likely to be endorsed by individuals with PTSD than without PTSD (χ2 = 25.68, p < .001). In regression analyses, PTSD was associated with increased likelihood of self-medication (odds ratio [OR] = 4.56) and help seeking (OR = 2.29), while AUD was associated with decreased likelihood of help-seeking (OR = .29). When self-medication was included as a predictor, PTSD was no longer associated with help seeking, although AUD remained inversely associated. PTSD and AUDs have a nuanced relationship with formal help seeking as well as the use of substances to cope. Trauma-exposed individuals are likely engaging in adaptive and maladaptive coping strategies, the latter of which may be compounding distress. (PsycINFO Database Record

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.

The Genetics of Stress-Related Disorders: PTSD, Depression, and Anxiety Disorders

Research into the causes of psychopathology has largely focused on two broad etiologic factors: genetic vulnerability and environmental stressors. An important role for familial/heritable factors in the etiology of a broad range of psychiatric disorders was established well before the modern era of genomic research. This review focuses on the genetic basis of three disorder categories-posttraumatic stress disorder (PTSD), major depressive disorder (MDD), and the anxiety disorders-for which environmental stressors and stress responses are understood to be central to pathogenesis. Each of these disorders aggregates in families and is moderately heritable. More recently, molecular genetic approaches, including genome-wide studies of genetic variation, have been applied to identify specific risk variants. In this review, I summarize evidence for genetic contributions to PTSD, MDD, and the anxiety disorders including genetic epidemiology, the role of common genetic variation, the role of rare and structural variation, and the role of gene-environment interaction. Available data suggest that stress-related disorders are highly complex and polygenic and, despite substantial progress in other areas of psychiatric genetics, few risk loci have been identified for these disorders. Progress in this area will likely require analysis of much larger sample sizes than have been reported to date. The phenotypic complexity and genetic overlap among these disorders present further challenges. The review concludes with a discussion of prospects for clinical translation of genetic findings and future directions for research.

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.

Parents' Prenatal Mental Health and Emotional, Behavioral and Social Development in Their Children

This study examines the association between expectant parents' psychological distress and children's development at 36 months old. This is a prospective population study based on the Norwegian Mother and Child Cohort Study, N = 31,663. Logistic regression models were used to assess whether high scores (cutoff ≥ 2.00) on the symptom checklist-5 in parents predicted higher levels (cutoff ≥ 90 percentile) of developmental problems in their children. The risk of emotional and behavioral problems were significantly increased in children when both parents were affected by psychological distress during pregnancy, fully adjusted OR 2.35 (95% CI 1.36, 4.07) and OR 2.65 (96% CI 1.564.48), respectively. The risk was higher when mothers reported high level of psychological distress than when only the fathers did, but the risk of emotional difficulties in children was highest when both parents presented high levels of psychological distress, indicating an additive effect of parental psychological distress.

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.

Single Nucleotide Polymorphism Heritability of Behavior Problems in Childhood: Genome-Wide Complex Trait Analysis

OBJECTIVE

Genetic factors contribute to individual differences in behavior problems. In children, genome-wide association studies (GWAS) have yielded the first suggestive results when aiming to identify genetic variants that explain heritability, but the proportion of genetic variance that can be attributed to common single nucleotide polymorphisms (SNPs) remains to be determined, as only a few studies have estimated SNP heritability, with diverging results.

METHOD

Genomic-relationship-matrix restricted maximum likelihood (GREML) as implemented in the software Genome-Wide Complex Trait Analysis (GCTA) was used to estimate SNP heritability (SNP h(2)) for multiple phenotypes within 4 broad domains of children's behavioral problems (attention-deficit/hyperactivity symptoms, internalizing, externalizing, and pervasive developmental problems) and cognitive function. We combined phenotype and genotype data from 2 independent, population-based Dutch cohorts, yielding a total number of 1,495 to 3,175 of 3-, 7-, and 9-year-old children.

RESULTS

Significant SNP heritability estimates were found for attention-deficit/hyperactivity symptoms (SNP h(2) = 0.37-0.71), externalizing problems (SNP h(2) = 0.44), and total problems (SNP h(2) = 0.18), rated by mother or teacher. Sensitivity analyses with exclusion of extreme cases and quantile normalization of the phenotype data decreased SNP h(2) as expected under genetic inheritance, but they remained statistically significant for most phenotypes.

CONCLUSION

We provide evidence of the influence of common SNPs on child behavior problems in an ethnically homogenous sample. These results support the continuation of large GWAS collaborative efforts to unravel the genetic basis of complex child behaviors.

Child developmental outcomes in preschool children following antidepressant exposure in pregnancy

OBJECTIVE

To examine child developmental outcomes in preschool-aged children exposed to antidepressant medication in pregnancy and compare their outcomes to children not exposed.

METHOD

A prospective case-controlled study of 20 children exposed to antidepressants in pregnancy and 21 unexposed controls was available from the Victorian Psychotropic Registry. Child development outcomes at 4 years of age were assessed using the Wechsler Preschool and Primary Scale of Intelligence, third edition; the Movement Assessment Battery for Children; Behaviour Rating Inventory of Executive Functioning-Preschool; and the Child Behavior Checklist (1.5-5 years). Maternal depression was assessed using the Beck Depression Inventory-II in pregnancy and at four time points across infancy and early childhood.

RESULTS

Children exposed to antidepressants in pregnancy had no statistically significant differences compared to unexposed children on any of the measures of child development undertaken. There was a trend to slightly lower scores in motor development with a small effect size for two scales of the Movement Assessment Battery for Children: balance - Cohen's d=0.36; aiming and catching - Cohen's d=0.34.

CONCLUSIONS

The finding of no effect on cognition and behaviour are consistent with other previous studies conducted with younger children. Likewise, the trend towards lower motor development is similar to earlier findings from this study and a number of other similar studies. Given this trend there is a need for future research that focuses on this area of development in older children using robust measures of motor development.

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.