Joint factorial structure of psychopathology and personality

Age-Related Variations of Genetic and Environmental Contributions to the Covariation of Fear, Distress and Externalizing Symptoms: A Twin Study in Childhood and Adolescence

The frequency with which Internalizing and Externalizing symptoms co-occur suggests that, behind both domains, there may be a common susceptibility represented by a general psychopathology factor. However, it's still unclear whether this common susceptibility is affected by age-related variations. Internalizing (i.e., Fear and Distress) and Externalizing symptoms were evaluated in 803 twin pairs from the population-based Italian Twin Registry. Model-fitting analysis was performed separately in the 6-14 and 15-18 age groups to estimate genetic and environmental contributions to the covariance among symptoms. For the 6-14 group, a multivariate Cholesky model best fitted the data, while, for the 15-18 group, the best fit was provided by a Common Pathway model in which nearly 50% of total variance of each trait was mediated by common genetic factors. Our findings support a common susceptibility behind Internalizing and Externalizing symptoms, mainly genetic in origin, that becomes more evident at the beginning of puberty.

Bifactor models of psychopathology using multi-informant and multi-instrument dimensional measures in the ABCD study

Background

Due to limitations of categorical definitions of mental illness, there is a need for quantitative empirical investigations of the dimensional structure of psychopathology. Using exploratory bifactor methods, this study investigated a comprehensive and representative structure of psychopathology in children to better understand how psychotic-like experiences (PLEs), autism spectrum disorder (ASD) symptoms, impulsivity, and sensitivity to reward and punishment, may be integrated into extant general factor models of psychopathology.

Methods

We used seven child-report and three parent-report instruments capturing diverse mental health symptoms in 11,185 children aged 9-10 from the Adolescent Brain Cognitive DevelopmentSM (ABCD) Study. We built on previous modeling frameworks by conducting both split sample and full sample factor analytic approaches that harnessed recent methodological advances in bifactor exploratory structural equation modeling (B-ESEM) to examine a wide range of psychopathology measures not previously integrated into a single analysis. Validity of psychopathology dimensions was examined by investigating associations with sex, age, cognition, imaging measures, and medical service usage.

Results

All four factor analytic models showed excellent fit and similar structure within informant. PLEs loaded most highly onto a general psychopathology factor, suggesting that they may reflect non-specific risk for mental illness. ASD symptoms loaded separately from attention/hyperactivity symptoms. Symptoms of impulsivity and sensitivity to reward and punishment loaded onto specific factors, distinct from externalizing and internalizing factors. All identified factors were associated with clinically relevant risk factors, providing preliminary evidence for their construct validity.

Conclusion

By integrating diverse child-report and parent-report psychopathology measures for children in the ABCD sample, we deliver data on the quantitative structure of psychopathology for an exceptionally large set of measurements and discuss implications for the field.

Distal-to-proximal etiologically relevant variables associated with the general (p) and specific factors of psychopathology

BACKGROUND

The general factor of psychopathology, often denoted as p, captures the common variance among a broad range of psychiatric symptoms. Specific factors are co-modeled based on subsets of closely related symptoms. This paper investigated the extent to which wide-ranging genetic, personal, and environmental etiologically relevant variables are associated with p and specific psychopathology factors.

METHODS

Using data from four waves (ages 11-19) of TRAILS, we modeled a bifactor model of p and four specific factors [internalizing, externalizing, ADHD, Autism Spectrum Disorder (ASD)]. Next, we examined the associations of 19 etiologically relevant variables with these psychology factors using path models that organized the variables according to the distal-to-proximal risk principle.

RESULTS

Collectively, the etiologically relevant factors, including temperament traits, accounted for 55% of p's variance, 46% in ADHD, 35% in externalizing, 19% in internalizing, and 7% in ASD. The low 7% is due to insufficient unique variance in ASD indicators that load more strongly on p. Excluding temperament, variables accounted for 29% variance in p, 9% ADHD, 14% EXT, 7% INT, and 4% ASD. Most etiologically relevant factors were generic, predicting p. In addition, we identified effects on specific factors in addition to effects on p (e.g., parental SES, executive functioning); only effects on specific factors (e.g., parental rejection); opposite effects on different factors [e.g., diurnal cortisol (high INT but low EXT, p); developmental delay (high ASD and p but low EXT)]. Frustration, family functioning, parental psychopathology, executive functioning, and fearfulness had strong effects on p.

CONCLUSIONS

(1) Strong generic effects on p suggest that etiologically relevant factors and psychopathology tend to cluster in persons. (2) While many factors predict p, additional as well as opposite effects on specific factors indicate the relevance of specific psychopathology factors in understanding mental disorder. (3) High frustration, neurodevelopmental problems, and a disadvantaged family environment primarily characterize p.

The structure of psychiatric comorbidity without selection and assortative mating

The widespread comorbidity observed across psychiatric disorders may be the result of processes such as assortative mating, gene-environment correlation, or selection into population studies. Between-family analyses of comorbidity are subject to these sources of bias, whereas within-family analyses are not. Because of Mendelian inheritance, alleles are randomly assigned within families, conditional on parental alleles. We exploit this variation to compare the structure of comorbidity across broad psychiatric polygenic scores when calculated either between-family (child polygenic scores) or within-family (child polygenic scores regressed on parental polygenic scores) in over 25,000 genotyped parent-offspring trios from the Norwegian Mother Father and Child Cohort study (MoBa). We fitted a series of factor models to the between- and within-family data, which consisted of a single genetic p-factor and a varying number of uncorrelated subfactors. The best-fitting model was identical for between- and within-family analyses and included three subfactors capturing variants associated with neurodevelopment, psychosis, and constraint, in addition to the genetic p-factor. Partner genetic correlations, indicating assortative mating, were not present for the genetic p-factor, but were substantial for the psychosis (b = 0.081;95% CI [0.038,0.124]) and constraint (b = 0.257;95% CI [0.075,0.439]) subfactors. When average factor levels for MoBa mothers and fathers were compared to a population mean of zero we found evidence of sex-specific participation bias, which has implications for the generalizability of findings from cohort studies. Our results demonstrate the power of the within-family design for better understanding the mechanisms driving psychiatric comorbidity and their consequences on population health.

Direction of dependence analysis for pre-post assessments using non-Gaussian methods: a tutorial

OBJECTIVE

We introduced methods for solving causal direction of dependence between variables observed in pre- and post-psychotherapy assessments, showing how to apply them and investigate their properties via simulations. In addition, we investigated whether changes in depressive symptoms drive changes in social and occupational functioning as suggested by the phase model of psychotherapy or vice versa, or neither.

METHOD

As a Gaussian (normal-distribution) model is unidentifiable here, we used an identifiable linear non-Gaussian structural vector autoregression model, conceptualizing instantaneous effects as during-psychotherapy causation and lagged effects as pre-treatment predictors of change. We tested six alternative estimators in six simulation settings that captured different real-world scenarios, and used real psychotherapy data from 1428 adult patients (Finnish Psychotherapy Quality Registry; assessments on Patient Health Questionnaire-9 and Social and Occupational Functioning Assessment Schedule).

RESULTS

The methodology was successful in identifying causal directions in simulated data. The real-data results provided no evidence for single direction of dependence, suggesting shared or reciprocal causation.

CONCLUSIONS

A powerful new tool was presented to investigate the process of psychotherapy using observational data. Application to patient data suggested that depression symptoms and functioning may reciprocate or reflect third variables instead of one predominantly driving the other during psychotherapy.

The p factor of psychopathology and personality in middle childhood: genetic and gestational risk factors

BACKGROUND

A joint, hierarchical structure of psychopathology and personality has been reported in adults but should also be investigated at earlier ages, as psychopathology often develops before adulthood. Here, we investigate the joint factor structure of psychopathology and personality in eight-year-old children, estimate factor heritability and explore external validity through associations with established developmental risk factors.

METHODS

Phenotypic and biometric exploratory factor analyses with bifactor rotation on genetically informative data from the Norwegian Mother, Father, and Child Cohort (MoBa) study. The analytic sub-sample comprised 10 739 children (49% girls). Mothers reported their children's symptoms of depression (Short Moods and Feelings Questionnaire), anxiety (Screen for Anxiety Related Disorders), attention-deficit/hyperactivity disorder inattention and hyperactivity, oppositional-defiant disorder, conduct disorder (Parent/Teacher Rating Scale for Disruptive Behavior Disorders), and Big Five personality (short Hierarchical Personality Inventory for Children). Developmental risk factors (early gestational age and being small for gestational age) were collected from the Medical Birth Registry.

RESULTS

Goodness-of-fit indices favored a p factor model with three residual latent factors interpreted as negative affectivity, positive affectivity, and antagonism, whereas psychometric indices favored a one-factor model. ADE solutions fitted best, and regression analyses indicated a negative association between gestational age and the p factor, for both the one- and four-factor solutions.

CONCLUSION

Correlations between normative and pathological traits in middle childhood mostly reflect one heritable and psychometrically interpretable p factor, although optimal fit to data required less interpretable residual latent factors. The association between the p factor and low gestational age warrants further study of early developmental mechanisms.

Social anxiety disorder is a risk factor for alcohol use problems in the National Comorbidity Surveys

BACKGROUND

According to the self-medication and biopsychosocial models, individuals with social anxiety disorder (SAD) are at increased risk of developing an alcohol use disorder (AUD) as alcohol represents a maladaptive coping mechanism for some sufferers of SAD. The SAD-to-AUD causation was earlier supported in Norwegian longitudinal twin data and later questioned using longitudinal data from the USA.

METHODS

We re-analyzed partly the same USA-based data (National Comorbidity Surveys, n = 5001), conducting theoretical and simulation analyses on different formulations of temporality and using real-data Logistic regression analysis to investigate whether baseline SAD was associated with AUD at the follow-up.

RESULTS

Upon proper analysis of temporality, SAD preceded AUD. Specifically, SAD was the only one of the seven anxiety disorders that predicted 10-year later AUD after adjusting for all other anxiety disorders and AUD at the baseline (odds ratio was 1.70% and 95% confidence interval 1.12-2.57). SAD was also associated with incident AUD (OR = 1.64, 95% CI = 1.14-2.37). We provide formal, simulation-based, and data-based arguments on how certain flawed models of incidence attenuate the temporal association.

CONCLUSIONS

We demonstrated temporality and specificity in SAD-to-AUD association, which are considered signs of causation. We further identified and discussed problems in previous statistical analyses with different conclusions. Our findings add support for models positing causal effects of SAD on AUD, such as the self-medication and biopsychosocial models. The available evidence suggests that treating SAD should incur better chances of preventing AUD compared to treating other anxiety disorders, which lack comparable evidence on causation.

Kind of blue - An evaluation of etiologies for prenatal versus postnatal depression symptoms

BACKGROUND

Prenatal and postnatal depression potentially have severe consequences, but we do not know to what extent they have the same etiological factors. Genetically informative designs yield insight into common etiology between pre- and postnatal depression and inform on potential prevention and intervention efforts. This study evaluates the overlap in genetic and environmental factors in pre- and postnatal depression symptoms.

METHODS

We conducted univariate and bivariate modeling, using a quantitative, extended twin study. The sample was a subsample of the MoBa prospective pregnancy cohort study in 6039 pairs of related women. Measurement was conducted at week 30 of pregnancy and 6 months following delivery, using a self-report scale.

RESULTS

The heritability of depressive symptoms was 16.2 % (95 % CI = 10.7-22.1) prenatally and 25.7 % (95 % CI = 19.2-32.2) postnatally. The correlation between risk factors for prenatal and postnatal depressive symptoms was at unity (r = 1.00) for genetic effects, and at disunity (r = 0.36) for environmental effects. The genetic effects for postnatal depressive symptoms were 1.7 times larger compared to prenatal depressive symptoms.

LIMITATIONS

Although genes for depression become more influential postpartum, only future studies can inform on the mechanisms for such a socio-biological augmentation of effect.

CONCLUSION

Genetic risk factors for prenatal and postnatal depressive symptoms are indistinguishable in kind, with greater impact after birth, whereas environmental risk factors for depression symptoms are mostly non-overlapping before and after birth. These findings indicate that interventions could be of different kind before and after birth.

Clustering psychopathology in male anabolic-androgenic steroid users and nonusing weightlifters

INTRODUCTION

Prior research has demonstrated that personality disorders and clinical psychiatric syndromes are common among users of anabolic-androgenic steroids (AAS). However, the prevalence, expression, and severity of psychopathology differ among AAS users and remain poorly understood. In this study, we examine the existence of potential clinically coherent psychopathology subgroups, using cluster procedures.

METHODS

A sample of 118 male AAS users and 97 weightlifting nonusers was assessed using the Millon Clinical Multiaxial Inventory-III (MCMI-III), measuring personality disorders and clinical syndromes. Group differences in MCMI-III scales were assessed using Wilcoxon-Mann-Whitney tests and Fisher's exact test. Agglomerative hierarchical clustering was used to identify clusters based on MCMI-III scale scores from the whole sample.

RESULTS

AAS users displayed significantly higher scores on all personality disorder (except narcissistic) and clinical syndrome scales compared to nonusing weightlifters. The clustering analysis found four separate clusters with different levels and patterns of psychopathology. The "no psychopathology" cluster was most common among nonusing weightlifters, while the three other clusters were more common among AAS users: "severe multipathology," "low multipathology," and "mild externalizing." The "severe multipathology" cluster was found almost exclusively among AAS users. AAS users also displayed the highest scores on drug and alcohol dependence syndromes.

CONCLUSIONS

AAS users in our sample demonstrated greater psychopathology than the nonusing weightlifters, with many exhibiting multipathology. This may pose a significant challenge to clinical care for AAS users, particularly as there appears to be significant variation in psychopathology in this population. Individual psychiatric profiles should be taken into consideration when providing treatment to this group.

SIGNIFICANT OUTCOMES

As a group, AAS users displayed markedly greater psychopathology than nonusing weightlifters. Multipathology was common among AAS users. Four different subgroups of personality profiles were identified with distinct patterns of pathology and severity.

LIMITATIONS

The cross-sectional nature of the study precludes inferences about causality. The study is limited by possible selection bias, as participants choosing to be involved in research may not be entirely representative for the group as a whole. The study is vulnerable to information bias, as the results are based on self-report measures and interviews.

Measurement Invariant but Non-Normal Treatment Responses in Guided Internet Psychotherapies for Depressive and Generalized Anxiety Disorders

Assessment of treatment response in psychotherapies can be undermined by lack of longitudinal measurement invariance (LMI) in symptom self-report inventories, by measurement error, and/or by wrong model assumptions. To understand and compare these threats to validity of outcome assessment in psychotherapy research, we studied LMI, sum scores, and Davidian Curve Item Response Theory models in a naturalistic guided internet psychotherapy treatment register of 2,218 generalized anxiety disorder (GAD) patients and 3,922 depressive disorder (DD) patients (aged ≥16 years). Symptoms were repeatedly assessed by Generalized Anxiety Disorder Assessment-7 (GAD-7) or Beck Depression Inventory. The symptom self-reports adhered to LMI under equivalence testing, suggesting sum scores are reasonable proxies for disorder status. However, the standard LMI assumption of normally distributed latent factors did not hold and inflated treatment response estimates by 0.2 to 0.3 standard deviation units compared with sum scores. Further methodological research on non-normally distributed latent constructs holds promise in advancing LMI and mental health assessment.

Maternal depression and the polygenic p factor: A family perspective on direct and indirect effects

Within-family studies typically assess indirect genetic effects of parents on children, however social support theory points to a critical role of partners and children on women's depression. To address this research gap and account for the high heterogeneity of depression, we calculated a general psychiatric factor using eleven major psychiatric polygenic scores (polygenic p), in up to 25,000 parent-offspring trios from the Norwegian Mother, Father and Child Cohort Study (MoBa). Multilevel modeling of trio polygenic p was used to distinguish direct and indirect genetic effects on mothers depression during pregnancy (gestational age 17 and 30 weeks), infancy (6 months, 18 months) and early childhood (3 years, 5 years, and 8 years). We found mothers polygenic p predicts their depression symptoms (b = 0.092; 95 % CI [0.087,0.098]), outperforming prediction using a single major depressive disorder polygenic score (b = 0.070, 95 % CI [0.066,0.075]). Jointly modeling trio polygenic p revealed indirect genetic effects of fathers (b = 0.022, 95 % CI [0.014,0.030]) and children (b = 0.021, 95 % CI [0.010,0.037]) on mothers' depression. Our results support the generalizability of polygenic effects across mental health and highlight the role of close family members on women's depression.

Social media as an incubator of personality and behavioral psychopathology: Symptom and disorder authenticity or psychosomatic social contagion?

There has been an increasing recognition among both medical and psychological professionals, as well as the public media, of a concerning trend for child and adolescent users of audiovisual-based, algorithmic social media platforms (e.g., TikTok) to present with or claim functional psychiatric impairment that is inconsistent with or distinct from classic psychiatric nosology. In this short communication, we provide a detailed historical overview of this transdiagnostic phenomenon and suggest a conceptual model to organize thinking and research examining it. We then discuss the implications of our suggested model for accurate assessment, diagnosis, and medical-psychiatric treatment. We believe there is an urgent need for focused empirical research investigation into this concerning phenomenon that is related to the broader research and discourse examining social media influences on mental health.

The joint hierarchical structure of psychopathology and dysfunctional personality domain indicators among community-dwelling adults

To examine the hierarchical structure of psychopathology and dysfunctional personality domains, 2416 Italian community-dwelling adult volunteers were administered a set of psychometrically sound psychopathology measures and the Personality Inventory for DSM-5 Brief Form+ (PID-5-BF+). Parallel analysis, minimum average partial, and very simple structure results suggested that 1-6 principal components (PCs) should be retained. Goldberg's bass-ackwards model of the joint psychopathology measure and PID-5-BF+ ipsatized domain scale correlation matrix evidenced a hierarchical structure that was consistent with the working model proposed by the Hierarchical Taxonomy of Psychopathology (HiTOP) consortium. Hierarchical agglomerative cluster analysis around latent variables of the psychopathology indicators and PID-5-BF+ domain scales recovered four latent dimensions, which were akin to the corresponding bass-ackwards components and nicely reproduced the HiTOP Internalizing, Externalizing, Thought Disorder, and Eating Pathology dimensions.

Inter-Rater Reliability of the Structured Interview of DSM-IV Personality (SIDP-IV) in an Adolescent Outpatient Population

Personality disorders (PDs) are a class of mental disorders which are associated with subjective distress, decreased quality of life and broad functional impairment. The presence of one or several PDs may also complicate the course and treatment of symptom disorders such as anxiety and depression. Accurate and reliable means of diagnosing personality disorders are thus crucial to ensuring efficient treatment planning and resource allocation, a fact which is widely acknowledged within the adult mental health field. In adolescents, on the other hand, the consensus view has been that the rapid and discontinuous processes of normal personality development render the construct of PD in adolescents clinically unhelpful and conceptually dubious. However, recent research has established the reliability and validity of the construct, heralding an increased interest in the field, with important conceptual and clinical implications. The present article presents reliability data for the Structured Interview of DSM-IV Personality (SIDP-IV) in an adolescent outpatient population. For this study, 25 interviews conducted by experienced clinicians were blindly re-scored based on sound recordings, which allowed for the calculation of intra-class correlation metrics. The intra-class correlation coefficient for categorical diagnosis of specific personality disorders was found to be 0.876 (95% CI 0.718-0.945); Cohen's kappa for presence/absence of personality diagnosis was found to be 0.896. The present study found excellent intra-rater reliability for the sample, which suggests that the SIDP-IV is a suitable instrument for assessing personality pathology in adolescent populations.

Intergenerational transmission of psychopathology: An examination of symptom severity and directionality

The present study examined the intergenerational transmission of internalizing and externalizing symptom severity, which indexes comorbidity, and symptom directionality, which indicates differentiation toward externalizing versus internalizing problems. Data are from 854 male and female, same-sex adult twin pairs born between 1926 and 1971 (32-60 years old, M = 44.9 years, SD = 4.9 years) from the Twin and Offspring Study in Sweden and their adolescent offspring (11-22 years old, M = 15.7 years, SD = 2.4 years, 52% female). Children-of-twins models revealed additive (9%) and dominant (45%) genetic and nonshared environmental (47%) influences on twins' symptom severity, and additive genetic (39%) and nonshared environmental (61%) influences on twins' symptom directionality. Both comorbid problems and preponderance of symptoms of a particular - internalizing versus externalizing - spectrum were correlated across parent and child generations, although associations were modest especially for directionality (i.e., transmission of specific symptom type). By interpreting findings alongside a recent study of adolescent twins, we demonstrate that the intergenerational transmission of symptom severity and symptom directionality are both unlikely to be attributable to genetic transmission, are both likely to be influenced by direct phenotypic transmission and/or nonpassive rGE, and the intergenerational transmission of symptom severity is also likely to be influenced by passive rGE.

Feasibility of generic, short, and easy-to-use assessment of psychological distress during psychotherapy: Longitudinal measurement invariance of CORE-10 and -OM

Objective: While the CORE-10 inventory for Clinical Outcome Routine Evaluation has shown good psychometric properties in cross-sectional assessment, the feasibility of generic, short, and easy-to-use longitudinal assessment of a broadband construct such as the targeted "general psychological distress" remains to be psychometrically demonstrated. Therefore, we investigated longitudinal measurement invariance (LMI) of CORE-10. For comprehensiveness, we also analyzed its parent inventory, CORE-OM.

Method: We investigated the LMI of pre- and post-therapy CORE-10 and -OM assessments in a naturalistic treatment register of 1715 patients' short psychotherapies, testing whether the construct of "psychological distress" remained the same across the treatments.

Results: We observed good psychometric properties and no violations of LMI for CORE-10 in chi-squared equivalence tests, nor in effect-size-based evaluations. Only the highly sensitive chi-squared difference tests detected LMI violations but these had little practical influence. The CORE-OM data did not fit well with factorial models but this was cross-sectional rather than a genuinely longitudinal (LMI-related) issue.

Conclusions: CORE-10 appeared a structurally valid measure of general psychological distress and suitable for longitudinal assessment, whereas the CORE-OM had a less clear factorial structure. Regarding psychometrics, these findings support the use of CORE-10 in longitudinal assessment during psychotherapy and do not support CORE-OM.

Genetic correlation, pleiotropy, and causal associations between substance use and psychiatric disorder

BACKGROUND

Substance use occurs at a high rate in persons with a psychiatric disorder. Genetically informative studies have the potential to elucidate the etiology of these phenomena. Recent developments in genome-wide association studies (GWAS) allow new avenues of investigation.

METHOD

Using results of GWAS meta-analyses, we performed a factor analysis of the genetic correlation structure, a genome-wide search of shared loci, and causally informative tests for six substance use phenotypes (four smoking, one alcohol, and one cannabis use) and five psychiatric disorders (ADHD, anorexia, depression, bipolar disorder, and schizophrenia).

RESULTS

Two correlated externalizing and internalizing/psychosis factor were found, although model fit was beneath conventional standards. Of 458 loci reported in previous univariate GWAS of substance use and psychiatric disorders, about 50% (230 loci) were pleiotropic with additional 111 pleiotropic loci not reported from past GWAS. Of the 341 pleiotropic loci, 152 were associated with both substance use and psychiatric disorders, implicating neurodevelopment, cell morphogenesis, biological adhesion pathways, and enrichment in 13 different brain tissues. Seventy-five and 114 pleiotropic loci were specific to either psychiatric disorders or substance use phenotypes, implicating neuronal signaling pathway and clathrin-binding functions/structures, respectively. No consistent evidence for phenotypic causation was found across different Mendelian randomization methods.

CONCLUSIONS

Genetic etiology of substance use and psychiatric disorders is highly pleiotropic and involves shared neurodevelopmental path, neurotransmission, and intracellular trafficking. In aggregate, the patterns are not consistent with vertical pleiotropy, more likely reflecting horizontal pleiotropy or more complex forms of phenotypic causation.

Modeling assortative mating and genetic similarities between partners, siblings, and in-laws

Assortative mating on heritable traits can have implications for the genetic resemblance between siblings and in-laws in succeeding generations. We studied polygenic scores and phenotypic data from pairs of partners (n = 26,681), siblings (n = 2,170), siblings-in-law (n = 3,905), and co-siblings-in-law (n = 1,763) in the Norwegian Mother, Father and Child Cohort Study. Using structural equation models, we estimated associations between measurement error-free latent genetic and phenotypic variables. We found evidence of genetic similarity between partners for educational attainment (r_g = 0.37), height (r_g = 0.13), and depression (r_g = 0.08). Common genetic variants associated with educational attainment correlated between siblings above 0.50 (r_g = 0.68) and between siblings-in-law (r_g = 0.25) and co-siblings-in-law (r_g = 0.09). Indirect assortment on secondary traits accounted for partner similarity in education and depression, but not in height. Comparisons between the genetic similarities of partners and siblings indicated that genetic variances were in intergenerational equilibrium. This study shows genetic similarities between extended family members and that assortative mating has taken place for several generations.

The structure of dimensions of psychopathology in normative and clinical samples: Applying causal discovery to MMPI-2-RF scales to investigate clustering of psychopathology spectra and p-factors

We applied a Bayesian Constraint-based Causal Discovery method (BCCD) to examine the hierarchical structure of the Minnesota Multiphasic Personality Inventory-2-Restructured Form (MMPI-2-RF) Restructured Clinical (RC) scales. Two different general psychopathology super spectra (p-factor) scales were extracted from (1) all RC scales and (2) all RC scales except the RCd (Demoralization) scale. These p-factor scales were included in separate models to investigate the structure of dimensions of psychopathology in a normative (n = 3,242) and clinical (n = 2,466) sample, as well as the combined normative/clinical sample (N = 5,708), by applying the BCCD algorithm to obtain a data-driven reconstruction of the internal hierarchical structure of the MMPI-2-RF. Research on the underlying structure of the MMPI-2-RF has clinical relevance as well as conceptual relevance in the context of the HiTOP model. Results demonstrated that the syndromes measured with the RC-scales-in presence of a p-factor-cluster into six spectra: internalizing, disinhibited-externalizing, antagonistic-externalizing, thought disorder, detachment, and somatoform. These results may support a super spectrum construct, as it was necessary for obtaining a bottom-up reconstruction of this six-spectrum structure. We found support for superiority of a broad super spectrum with additional variance over and above demoralization, as it resulted in the clearest structure (i.e., clustering of the RC scales). Furthermore, our results indicate independent support for the bifactor structure model of psychopathology.

In light of the DSM-5 dimensional model of personality: Borderline personality disorder at the crossroads with the bipolar spectrum

BACKGROUND

State-of-the-art research highlights that borderline personality disorder (PD) and bipolar spectrum disorders have clinical characteristics in common, which imply uncertainty in differential diagnoses. Although there is a growing body of literature on the DSM-5 dimensional model of personality disorder, its discriminative features between these clinical samples are still understudied. In this study, we seek to identify the best set of predictors that differentiate between borderline PD and bipolar spectrum, based on pathological and normative personality traits and symptoms.

METHODS

A cross-sectional study of three clinical samples: 1) Borderline PD group of 63 participants; 2) Major depressive disorder group of 89 participants; 3) Bipolar disorder group of 65 participants. Self-reported assessment: Personality Inventory for DSM-5; Brief Symptom Inventory; FFM Inventory. A series of one-way ANOVAs and logistic regression analyses were computed.

RESULTS

The major set of data emerging as common discriminants of borderline PD across the bipolar spectrum are unusual beliefs & experiences, paranoid ideation, obsession-compulsion and extraversion. Depressivity (OR: 34.95) and impulsivity (OR: 22.35) pathological traits displayed the greatest predictive values in the differential diagnosis.

LIMITATIONS

The small size of the samples; a lack of data from participants' previous clinical history.

CONCLUSIONS

Findings support the DSM-5 pathological traits as differentiating borderline PD through bipolar spectrum, and reinforcing the joint use of symptom-related pathological functioning and normal-range personality traits. Alongside the bipolar spectrum, borderline pathology sheds light upon a hypothetical overlap along the depressive and schizoaffective/schizophrenia spectra, representing a borderland space at a crossroads with the psychopathology of a meta-spectrum.

Multivariate analysis of 1.5 million people identifies genetic associations with traits related to self-regulation and addiction

Behaviors and disorders related to self-regulation, such as substance use, antisocial behavior and attention-deficit/hyperactivity disorder, are collectively referred to as externalizing and have shared genetic liability. We applied a multivariate approach that leverages genetic correlations among externalizing traits for genome-wide association analyses. By pooling data from ~1.5 million people, our approach is statistically more powerful than single-trait analyses and identifies more than 500 genetic loci. The loci were enriched for genes expressed in the brain and related to nervous system development. A polygenic score constructed from our results predicts a range of behavioral and medical outcomes that were not part of genome-wide analyses, including traits that until now lacked well-performing polygenic scores, such as opioid use disorder, suicide, HIV infections, criminal convictions and unemployment. Our findings are consistent with the idea that persistent difficulties in self-regulation can be conceptualized as a neurodevelopmental trait with complex and far-reaching social and health correlates.

Culture and psychopathology: An attempt at reconsidering the role of social learning

This paper proposes a model for developmental psychopathology that is informed by recent research suggestive of a single model of mental health disorder (the p factor) and seeks to integrate the role of the wider social and cultural environment into our model, which has previously been more narrowly focused on the role of the immediate caregiving context. Informed by recently emerging thinking on the social and culturally driven nature of human cognitive development, the ways in which humans are primed to learn and communicate culture, and a mentalizing perspective on the highly intersubjective nature of our capacity for affect regulation and social functioning, we set out a cultural-developmental approach to psychopathology.

COVID-19 Pandemic and Helsinki University Hospital Personnel Psychological Well-Being: Six-Month Follow-Up Results

The COVID-19 pandemic has caused an unequally distributed extra workload to hospital personnel and first reports have indicated that especially front-line health care personnel are psychologically challenged. A majority of the Finnish COVID-19 patients are cared for in the Helsinki University Hospital district. The psychological distress of the Helsinki University Hospital personnel has been followed via an electronic survey monthly since June 2020. We report six-month follow-up results of a prospective 18-month cohort study. Individual variation explained much more of the total variance in psychological distress (68.5%, 95% CI 65.2-71.9%) and negative changes in sleep (75.6%, 95% CI 72.2-79.2%) than the study survey wave (1.6%, CI 0.5-5.5%; and 0.3%, CI 0.1-1.2%). Regional COVID-19 incidence rates correlated with the personnel's psychological distress. In adjusted multilevel generalized linear multiple regression models, potentially traumatic COVID-19 pandemic-related events (OR 6.54, 95% CI 5.00-8.56) and front-line COVID-19 work (OR 1.81, 95% CI 1.37-2.39) was associated with personnel psychological distress but age and gender was not. While vaccinations have been initiated, creating hope, continuous follow-up and psychosocial support is still needed for all hospital personnel.

Different Correlates of COVID-19-Related Adherent and Dysfunctional Safety Behavior

Introduction: Safety behaviors are key elements in reducing the spread of the COVID-19 virus, but have also assumed excessive proportions in form of panic buying groceries. This raises the question whether these behaviors are independent or related to each other. Adherent safety behavior including increased hygiene and physical distancing appears inherently adherent and prosocial, while dysfunctional safety behavior such as panic buying most probably emerges from other motives and contextual variables. Methods: Data from 15,308 participants collected from March 10 to May 4, 2020, during the COVID-19 acute period in Germany, was analyzed to assess whether adherent and dysfunctional safety behavior are predicted by the same or divergent variables. Two multiple regression models are presented including various sociodemographic, trait, attitudinal, and COVID-19-specific variables as predictors. Results: Some variables similarly predict both, adherent and dysfunctional safety behavior. Yet, adherent safety behavior is stronger predicted by COVID-19-related fear than generalized anxiety, while a trend toward a reverse pattern emerged for dysfunctional safety behavior. Adherent safety behavior was also related to higher trust in governmental actions to face COVID-19, subjective level of information, as well as use of public media and TV to remain informed on COVID-19. Higher age was related to dysfunctional, but not adherent safety behavior. Respondents living in rural communities report more adherent safety behavior than urban dwellers. Discussion: Divergent psychological variables underlie adherent and dysfunctional safety behavior. This hints toward a theoretical separation with practical relevance in behavioral engineering and public health campaigning.

Total and cause-specific mortality in patients with personality disorders: the association between comorbid severe mental illness and substance use disorders

PURPOSE

To investigate the mortality in both in- and outpatients with personality disorders (PD), and to explore the association between mortality and comorbid substance use disorder (SUD) or severe mental illness (SMI).

METHODS

All residents admitted to Norwegian in- and outpatient specialist health care services during 2009-2015 with a PD diagnosis were included. Standardized mortality ratios (SMRs) with 95% confidence intervals (CI) were estimated in patients with PD only and in patients with PD and comorbid SMI or SUD. Cox proportional hazards models were used to estimate adjusted hazard ratios (HRs) with 95% CIs in patients with PD and comorbid SMI or SUD compared to patients with PD only.

RESULTS

Mortality was increased in both in- and outpatients with PD. The overall SMR was 3.8 (95% CI 3.6-4.0). The highest SMR was estimated for unnatural causes of death (11.0, 95% CI 10.0-12.0), but increased also for natural causes of death (2.2, 95% CI 2.0-2.5). Comorbidity was associated with higher SMRs, particularly due to poisoning and suicide. Patients with comorbid PD & SUD had almost four times higher all-cause mortality HR than patients with PD only; young women had the highest HR.

CONCLUSION

The SMR was high in both in- and outpatients with PD, and particularly high in patients with comorbid PD & SUD. Young female patients with PD & SUD were at highest risk. The higher mortality in patients with PD cannot, however, fully be accounted for by comorbidity.

Phenotyping mental health: Age, community size, and depression differently modulate COVID-19-related fear and generalized anxiety

INTRODUCTION

When the first COVID-19 infections were reported in Germany, fear and anxiety spread faster than the pandemic itself. While moderate amounts of fear of a COVID-19 infection may be functional, generalized anxiety and the potentially resulting distress and psychopathology may possibly be detrimental to people's health. Authorities need to avoid a countrywide panic, on the one hand, but foster a realistic awareness of the actual threat, on the other hand.

OBJECTIVES

The current cross-sectional study aimed to investigate psychological reactions in response to the real or perceived infection threats. In particular, the analysis should reveal whether COVID-19-related fear and generalized anxiety in times of COVID-19 have distinct correlates.

METHODS

A nationwide study was conducted from March 10th to May 4th 2020 in Germany (n = 15,308; 10,824 women, 4433 men, 51 other). Generalized anxiety was assessed using the GAD-7, while COVID-19-related fear was measured using a self-generated item. Both outcome variables were entered into linear regression models. Demographic information, depressive symptoms, trust in governmental interventions, subjective level of information regarding COVID-19 and media use were used to predict generalized anxiety and COVID-19-related fear.

RESULTS

The data revealed distinct correlates of COVID-19-related fear and generalized anxiety. Although COVID-19-related fear and generalized anxiety had overlapping predictors, such as neuroticism, they most prominently differed in age distribution and direction of an urban-rural disparity: generalized anxiety decreases with age, but COVID-19-related fear is most pronounced in elderly participants. Generalized anxiety is also more prevalent in rural communities, but COVID-19-related fear is elevated in metropoles. Furthermore, the presence of a risk disease increases COVID-19-related fear, but not generalized anxiety.

CONCLUSION

These results suggest that COVID-19-related fear is often justified considering the individual risk of infection or complication due to infection. Some of the characteristics that predict COVID-19-related fear leave generalized anxiety unaffected or show divergent predictive directions. The present findings hint toward two related, but discriminant constructs.

Change in personality traits and facets (Revised NEO Personality Inventory) following metacognitive therapy or cognitive behaviour therapy for generalized anxiety disorder: Results from a randomized controlled trial

OBJECTIVE

We aimed to discover whether psychological treatment for generalized anxiety disorder (GAD) was associated with changes in the big five personality traits and their facets.

METHOD

Patients with GAD were randomized either to receive cognitive behaviour therapy (CBT, n = 28) or metacognitive therapy (MCT, n = 32). Before and after 12 sessions of treatment, 55 of the patients completed the full Revised NEO Personality Inventory (NEO-PI-R) (240 items).

RESULTS

Patients with GAD showed a personality profile with high Neuroticism and lower Extraversion and Openness. Treatment across conditions was associated with significant reduction in Neuroticism and increased Extraversion and Openness. There were no significant changes in Agreeableness and Conscientiousness. However, their facets of Actions and Trust increased. Post-treatment levels of neuroticism were associated with symptoms of worry before and after therapy, whereas post-treatment extraversion was related to depressive symptoms after treatment. MCT was associated with greater reduction of Neuroticism than CBT.

CONCLUSIONS

This is the first study to show that efficient treatment for a specific disorder resulted in changes across NEO-PI-R factors and facets and that more efficient treatment results in greater change. If this reflects a reduced trait vulnerability for mental disorder, this might provide evidence of relapse prevention.

High levels of the openness trait are associated with better parental reflective functioning in mothers with substance use disorders

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Mothers with high levels of Openness had better parental reflective functioning.

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Mothers with low Openness need training in interpreting mental states in their children.

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It is important to assess the mothers personality before selecting form of treatment.

Aims

Mothers with substance use disorders (SUD) often show impairments in parental reflective functioning (PRF), which may have adverse effects on their capacity for sensitive caregiving. Parenting personality is also associated with caregiving. However, no studies have investigated how these individual factors may contribute to variance in PRF in mothers with SUD. In this study PRF and personality were assessed in 43 mothers with SUD.

Methods

PRF was assessed by the Parent Development Interview. Personality traits were assessed by the Revised Neuroticism-Extraversion-Openness Personality Inventory.

Results

The results indicate that higher levels of the Openness trait are associated with better PRF.

Conclusion

Mothers low in Openness may need more specific and situational training in interpreting mental states in their children. Highly open mothers with SUD will likely need more help distinguishing the child’s mental states from their own, and might need help to maintain mutuality and regulating the intensity of their responses to the child’s behavior.

Integrating the study of personality and psychopathology in the context of gene-environment correlations across development

OBJECTIVE

A key principle of individual differences research is that biological and environmental factors jointly influence personality and psychopathology. Genes and environments interact to influence the emergence and stability of both normal and abnormal behavior (i.e., genetic predisposition, X, is exacerbated or buffered under environmental conditions, Y, or vice versa), including by shaping the neural circuits underpinning behavior. The interplay of genes and environments is also reflected in various ways in which they are correlated (i.e., rGE). That is, the same genetic factors that give rise to personality or psychopathology also shape that person's environment.

METHODS

In this review, we outline passive, evocative, and active rGE processes and review the findings of studies that have addressed rGE in relation to understanding individual differences in personality and psychopathology across development.

RESULTS

Throughout, we evaluate the question of whether it is possible, not only to differentiate the person from their problems, but also to differentiate the person from their problems and their environment.

CONCLUSIONS

We provide recommendations for future research to model rGE and better inform our ability to study personality and psychopathology, while separating the influence of the environment.

Testing relationships between multimodal modes of brain structural variation and age, sex and polygenic scores for neuroticism in children and adolescents

Human brain development involves spatially and temporally heterogeneous changes, detectable across a wide range of magnetic resonance imaging (MRI) measures. Investigating the interplay between multimodal MRI and polygenic scores (PGS) for personality traits associated with mental disorders in youth may provide new knowledge about typical and atypical neurodevelopment. We derived independent components across cortical thickness, cortical surface area, and grey/white matter contrast (GWC) (n = 2596, 3-23 years), and tested for associations between these components and age, sex and-, in a subsample (n = 878), PGS for neuroticism. Age was negatively associated with a single-modality component reflecting higher global GWC, and additionally with components capturing common variance between global thickness and GWC, and several multimodal regional patterns. Sex differences were found for components primarily capturing global and regional surface area (boys > girls), but also regional cortical thickness. For PGS for neuroticism, we found weak and bidirectional associations with a component reflecting right prefrontal surface area. These results indicate that multimodal fusion is sensitive to age and sex differences in brain structure in youth, but only weakly to polygenic load for neuroticism.

Genetic Associations Between Childhood Psychopathology and Adult Depression and Associated Traits in 42 998 Individuals: A Meta-analysis

Importance

Adult mood disorders are often preceded by behavioral and emotional problems in childhood. It is yet unclear what explains the associations between childhood psychopathology and adult traits.

Objective

To investigate whether genetic risk for adult mood disorders and associated traits is associated with childhood disorders.

Design, Setting, and Participants

This meta-analysis examined data from 7 ongoing longitudinal birth and childhood cohorts from the UK, the Netherlands, Sweden, Norway, and Finland. Starting points of data collection ranged from July 1985 to April 2002. Participants were repeatedly assessed for childhood psychopathology from ages 6 to 17 years. Data analysis occurred from September 2017 to May 2019.

Exposures

Individual polygenic scores (PGS) were constructed in children based on genome-wide association studies of adult major depression, bipolar disorder, subjective well-being, neuroticism, insomnia, educational attainment, and body mass index (BMI).

Main Outcomes and Measures

Regression meta-analyses were used to test associations between PGS and attention-deficit/hyperactivity disorder (ADHD) symptoms and internalizing and social problems measured repeatedly across childhood and adolescence and whether these associations depended on childhood phenotype, age, and rater.

Results

The sample included 42 998 participants aged 6 to 17 years. Male participants varied from 43.0% (1040 of 2417 participants) to 53.1% (2434 of 4583 participants) by age and across all cohorts. The PGS of adult major depression, neuroticism, BMI, and insomnia were positively associated with childhood psychopathology (β estimate range, 0.023-0.042 [95% CI, 0.017-0.049]), while associations with PGS of subjective well-being and educational attainment were negative (β, -0.026 to -0.046 [95% CI, -0.020 to -0.057]). There was no moderation of age, type of childhood phenotype, or rater with the associations. The exceptions were stronger associations between educational attainment PGS and ADHD compared with internalizing problems (Δβ, 0.0561 [Δ95% CI, 0.0318-0.0804]; ΔSE, 0.0124) and social problems (Δβ, 0.0528 [Δ95% CI, 0.0282-0.0775]; ΔSE, 0.0126), and between BMI PGS and ADHD and social problems (Δβ, -0.0001 [Δ95% CI, -0.0102 to 0.0100]; ΔSE, 0.0052), compared with internalizing problems (Δβ, -0.0310 [Δ95% CI, -0.0456 to -0.0164]; ΔSE, 0.0074). Furthermore, the association between educational attainment PGS and ADHD increased with age (Δβ, -0.0032 [Δ 95% CI, -0.0048 to -0.0017]; ΔSE, 0.0008).

Conclusions and Relevance

Results from this study suggest the existence of a set of genetic factors influencing a range of traits across the life span with stable associations present throughout childhood. Knowledge of underlying mechanisms may affect treatment and long-term outcomes of individuals with psychopathology.

Dimensions over categories: a meta-analysis of taxometric research

Taxometric procedures have been used extensively to investigate whether individual differences in personality and psychopathology are latently dimensional or categorical ('taxonic'). We report the first meta-analysis of taxometric research, examining 317 findings drawn from 183 articles that employed an index of the comparative fit of observed data to dimensional and taxonic data simulations. Findings supporting dimensional models outnumbered those supporting taxonic models five to one. There were systematic differences among 17 construct domains in support for the two models, but psychopathology was no more likely to generate taxonic findings than normal variation (i.e. individual differences in personality, response styles, gender, and sexuality). No content domain showed aggregate support for the taxonic model. Six variables - alcohol use disorder, intermittent explosive disorder, problem gambling, autism, suicide risk, and pedophilia - emerged as the most plausible taxon candidates based on a preponderance of independently replicated findings. We also compared the 317 meta-analyzed findings to 185 additional taxometric findings from 96 articles that did not employ the comparative fit index. Studies that used the index were 4.88 times more likely to generate dimensional findings than those that did not after controlling for construct domain, implying that many taxonic findings obtained before the popularization of simulation-based techniques are spurious. The meta-analytic findings support the conclusion that the great majority of psychological differences between people are latently continuous, and that psychopathology is no exception.

Genetic and environmental risk structure of internalizing psychopathology in youth

BACKGROUND

Internalizing disorders (IDs), consisting of syndromes of anxiety and depression, are common, debilitating conditions often beginning early in life. Various trait-like psychological constructs are associated with IDs. Our prior analysis identified a tripartite model of Fear/Anxiety, Dysphoria, and Positive Affect among symptoms of anxiety and depression and the following constructs in youth: anxiety sensitivity, fearfulness, behavioral activation and inhibition, irritability, neuroticism, and extraversion. The current study sought to elucidate their overarching latent genetic and environmental risk structure.

METHODS

The sample consisted of 768 juvenile twin subjects ages 9-14 assessed for the nine, abovementioned measures. We compared two multivariate twin models of this broad array of phenotypes.

RESULTS

A hypothesis-driven, common pathway twin model reflecting the tripartite structure of the measures were fit to these data. However, an alternative independent pathway model provided both a better fit and more nuanced insights into their underlying genetic and environmental risk factors.

CONCLUSIONS

Our findings suggest a complex latent genetic and environmental structure to ID phenotypes in youth. This structure, which incorporates both clinical symptoms and various psychological traits, informs future phenotypic approaches for identifying specific genetic and pathophysiological mechanisms underlying ID risk.

A test of the goodness of fit of the generic metacognitive model of psychopathology symptoms

BACKGROUND

Common mental disorders such as depression and anxiety frequently co-occur and may share etiological mechanisms. The metacognitive model is based on the principle that there are common pathological mechanisms across disorders that account for comorbidity and therefore can be conceptualized in one generic model. A central prediction of the model is that particular metacognitive beliefs concerning the value of worry, and the uncontrollability and danger of cognition are positively correlated with psychopathology symptoms. In the present study, we set out to test the overall fit of this model by assessing generic metacognitive beliefs and judgements of attention control capacity as predictors of common and frequently co-occurring emotional distress symptoms.

METHODS

In a cross-sectional design, 645 participants gathered at convenience completed a battery of self-report questionnaires.

RESULTS

Structural equation modelling indicated a good model fit for the generic metacognitive model, and the predictors accounted for 93% of the variance in distress consisting of depression-, generalized- and social anxiety symptoms.

CONCLUSIONS

This finding supports the generic model and the implication that it can be used as a basis to formulate and treat multiple presenting problems.

A Brief but Comprehensive Review of Research on the Alternative DSM-5 Model for Personality Disorders

PURPOSE OF REVIEW

Both the Alternative DSM-5 Model for Personality Disorders (AMPD) and the chapter on personality disorders (PD) in the recent version of ICD-11 embody a shift from a categorical to a dimensional paradigm for the classification of PD. We describe these new models, summarize available measures, and provide a comprehensive review of research on the AMPD.

RECENT FINDINGS

A total of 237 publications on severity (criterion A) and maladaptive traits (criterion B) of the AMPD indicate (a) acceptable interrater reliability, (b) largely consistent latent structures, (c) substantial convergence with a range of theoretically and clinically relevant external measures, and (d) some evidence for incremental validity when controlling for categorical PD diagnoses. However, measures of criterion A and B are highly correlated, which poses conceptual challenges. The AMPD has stimulated extensive research with promising findings. We highlight open questions and provide recommendations for future research.

What Lies Beneath Trait-Anxiety? Testing the Self-Regulatory Executive Function Model of Vulnerability

Vulnerability to psychological disorder can be assessed with constructs such as trait anxiety and neuroticism which among others are transdiagnostic risk factors. However, trait-anxiety and related concepts have been criticised because they don't illuminate the etiological mechanisms of psychopathology. In contrast, the metacognitive (S-REF) model offers a framework in which metacognitive knowledge conceptualised in trait terms is part of a core mechanism underlying trait-anxiety and related constructs. The present study therefore set out to explore metacognitions as potential underlying factors in trait-anxiety (the propensity to depression and anxiety). Nine hundred and eighty two participants completed self-report measures of metacognitions and trait-anxiety at time 1, and 425 individuals completed the same measures 8 weeks later. At the cross-sectional level, metacognitions accounted for 83% of the variance in anxiety- and 64% of depression propensity. Furthermore, despite both domains of trait-anxiety showing high stability over time, negative- and positive metacognitive beliefs were significant prospective predictors of both domains of vulnerability. These findings suggests that metacognitive beliefs may be an underlying mechanism of vulnerability attributed to trait-anxiety with the implication that the metacognitive (S-REF) model informs conceptualization of psychological vulnerability, and that metacognitive therapy applications might be employed to enhance psychological resilience.

The General Psychopathology Factor: Structural Stability and Generalizability to Within-Individual Changes

Objectives: Although cross-sectional investigations have found a bifactor structure of psychiatric comorbidity that includes a general psychopathology factor plus more specific factors, prospective evidence supporting the bifactor structure is still limited. We evaluated the structural stability (i.e., longitudinal invariance) of the bifactor model in comparison to an alternative structure, a correlated factors model without a general psychopathology factor. We also investigated the models' generalizability to change processes in psychopathology. Methods: The analyses were conducted on 10-year follow-up data from 5,001 respondents in the US National Comorbidity Survey. Invariance was evaluated through a series of nested invariance tests using confirmatory factor analysis, and the models' generalizability to change processes was investigated using change scores of disorder status. Results: The bifactor model and the correlated factors model exhibited an equal degree of strong structural stability over time. Only the bifactor model satisfactorily characterized the structure of temporal changes in psychopathology. Conclusions: The bifactor structure with a general psychopathology factor is stable over time and describes temporal changes in psychopathology. The findings support the notion that the general psychopathology factor describes a transdiagnostic etiology and may therefore provide a useful target for intervention and treatment.