Changes in General and Specific Psychopathology Factors Over a Psychosocial Intervention

general psychopathology factor in Chinese adolescents and its correlation with trans-diagnostic protective psycho-social factors

BACKGROUND

Comorbidity in mental disorders is prevalent among adolescents, with evidence suggesting a general psychopathology factor ("p" factor) that reflects shared mechanisms across different disorders. However, the association between the "p" factor and protective factors remains understudied. The current study aimed to explore the "p" factor, and its associations with psycho-social functioning, in Chinese adolescents.

METHODS

2052 students, aged 9-17, were recruited from primary and secondary schools in Shanghai, China. Multiple rating scales were used to assess psychological symptoms and psycho-social functioning. Confirmatory factor analysis was conducted to verify the fit of models involving different psychopathology domains such as externalizing, internalizing, and the "p" factor. Subsequently, structural equation models were used to explore associations between the extracted factors and psycho-social functioning, including emotion regulation, mindful attention awareness, self-esteem, self-efficacy, resilience, and perceived support.

RESULTS

The bi-factor model demonstrated a good fit, with a "p" factor accounting for 46 % of symptom variation, indicating that the psychological symptoms of Chinese adolescents could be explained by internalizing, externalizing, and the "p" factor. Psychologically, a higher "p" was positively correlated with emotion suppression and negatively correlated with mindful attention awareness, emotion reappraisal, self-esteem, and resilience. Socially, a higher "p" was associated with decreased perceived support.

LIMITATIONS

Only common symptoms were included as this study was conducted at school. Furthermore, the cross-sectional design limited our ability to investigate causal relationships.

CONCLUSIONS

A "p" factor exists among Chinese adolescents. Individuals with higher "p" factor levels were prone to experience lower levels of psycho-social functions.

P-Factor(s) for Youth Psychopathology Across Informants and Models in 24 Societies

OBJECTIVE

Although the significance of the general factor of psychopathology (p) is being increasingly recognized, it remains unclear how to best operationalize and measure p. To test variations in the operationalizations of p and make practical recommendations for its assessment, we compared p-factor scores derived from four models.

METHODS

We compared p scores derived from principal axis (Model 1), hierarchical factor (Model 2), and bifactor (Model 3) analyses, plus a Total Problem score (sum of unit-weighted ratings of all problem items; Model 4) for parent- and self-rated youth psychopathology from 24 societies. Separately for each sample, we fitted the models to parent-ratings on the Child Behavior Checklist for Ages 6-18 (CBCL/6-18) and self-ratings on the Youth Self-Report (YSR) for 25,643 11-18-year-olds. Separately for each sample, we computed correlations between p-scores obtained for each pair of models, cross-informant correlations between p-scores for each model, and Q-correlations between mean item x p-score correlations for each pair of models.

RESULTS

Results were similar for all models, as indicated by correlations of .973-.994 between p-scores for Models 1-4, plus similar cross-informant correlations between CBCL/6-18 and YSR Model 1-4 p-scores. Item x p correlations had similar rank orders between Models 1-4, as indicated by Q correlations of .957-.993.

CONCLUSIONS

The similar results obtained for Models 1-4 argue for using the simplest model - the unit-weighted Total Problem score - to measure p for clinical and research assessment of youth psychopathology. Practical methods for measuring p may advance the field toward transdiagnostic patterns of problems.

Machine learning-based health environmental-clinical risk scores in European children

BACKGROUND

Early life environmental stressors play an important role in the development of multiple chronic disorders. Previous studies that used environmental risk scores (ERS) to assess the cumulative impact of environmental exposures on health are limited by the diversity of exposures included, especially for early life determinants. We used machine learning methods to build early life exposome risk scores for three health outcomes using environmental, molecular, and clinical data.

METHODS

In this study, we analyzed data from 1622 mother-child pairs from the HELIX European birth cohorts, using over 300 environmental, 100 child peripheral, and 18 mother-child clinical markers to compute environmental-clinical risk scores (ECRS) for child behavioral difficulties, metabolic syndrome, and lung function. ECRS were computed using LASSO, Random Forest and XGBoost. XGBoost ECRS were selected to extract local feature contributions using Shapley values and derive feature importance and interactions.

RESULTS

ECRS captured 13%, 50% and 4% of the variance in mental, cardiometabolic, and respiratory health, respectively. We observed no significant differences in predictive performances between the above-mentioned methods.The most important predictive features were maternal stress, noise, and lifestyle exposures for mental health; proteome (mainly IL1B) and metabolome features for cardiometabolic health; child BMI and urine metabolites for respiratory health.

CONCLUSIONS

Besides their usefulness for epidemiological research, our risk scores show great potential to capture holistic individual level non-hereditary risk associations that can inform practitioners about actionable factors of high-risk children. As in the post-genetic era personalized prevention medicine will focus more and more on modifiable factors, we believe that such integrative approaches will be instrumental in shaping future healthcare paradigms.

The mediating role of reflective functioning and general psychopathology in the relationship between childhood conduct disorder and adult aggression among offenders

BACKGROUND

The nature of the pathway from conduct disorder (CD) in adolescence to antisocial behavior in adulthood has been debated and the role of certain mediators remains unclear. One perspective is that CD forms part of a general psychopathology dimension, playing a central role in the developmental trajectory. Impairment in reflective functioning (RF), i.e., the capacity to understand one's own and others' mental states, may relate to CD, psychopathology, and aggression. Here, we characterized the structure of psychopathology in adult male-offenders and its role, along with RF, in mediating the relationship between CD in their adolescence and current aggression.

METHODS

A secondary analysis of pre-treatment data from 313 probation-supervised offenders was conducted, and measures of CD symptoms, general and specific psychopathology factors, RF, and aggression were evaluated through clinical interviews and questionnaires.

RESULTS

Confirmatory factor analyses indicated that a bifactor model best fitted the sample's psychopathology structure, including a general psychopathology factor (p factor) and five specific factors: internalizing, disinhibition, detachment, antagonism, and psychoticism. The structure of RF was fitted to the data using a one-factor model. According to our mediation model, CD significantly predicted the p factor, which was positively linked to RF impairments, resulting in increased aggression.

CONCLUSIONS

These findings highlight the critical role of a transdiagnostic approach provided by RF and general psychopathology in explaining the link between CD and aggression. Furthermore, they underscore the potential utility of treatments focusing on RF, such as mentalization-based treatment, in mitigating aggression in offenders with diverse psychopathologies.

A Developmentally Informed Systematic Review and Meta-Analysis of the Strength of General Psychopathology in Childhood and Adolescence

Considerable support exists for higher-order dimensional conceptualizations of psychopathology in adults. A growing body of work has focused on understanding the structure of general and specific psychopathology in children and adolescents. No prior meta-analysis has examined whether the strength of the general psychopathology factor (p factor)-measured by explained common variance (ECV)-changes from childhood to adolescence. The primary objective of this multilevel meta-analysis was to determine whether general psychopathology strength changes across development (i.e. across ages) in childhood and adolescence. Several databases were searched in November 2021; 65 studies, with 110 effect sizes (ECV), nested within shared data sources, were identified. Included empirical studies used a factor analytic modeling approach that estimated latent factors for child/adolescent internalizing, externalizing, and optionally thought-disordered psychopathology, and a general factor. Studies spanned ages 2-17 years. Across ages, general psychopathology explained over half (~ 56%) of the reliable variance in symptoms of psychopathology. Age-moderation analyses revealed that general factor strength remained stable across ages, suggesting that general psychopathology strength does not significantly change across childhood to adolescence. Even if the structure of psychopathology changes with development, the prominence of general psychopathology across development has important implications for future research and intervention.

Taking stock to move forward: Where the field of developmental psychopathology might be heading

In this paper, dedicated to Dante Cicchetti's contributions and enduring influence, we explore the prospective directions of developmental psychopathology. Our focus centers on key domains where Cicchetti's significant achievements have continually shaped our evolving thinking about psychological development. These domains include (a) the concepts of equifinality and multifinality, along with the challenges in predicting developmental trajectories, (b) the imperative to integrate wider sociocultural viewpoints into developmental psychopathology frameworks, (c) the interplay of genetic and environmental influences in developmental courses, (d) the significance of mental state language, and (e) the progress, or its absence, in the development of prevention and intervention tactics for children, adolescents, and their caregivers. While many of our forecasts regarding the future of developmental psychopathology may not materialize, we maintain optimistic that the essential ideas presented will influence the research agenda in this field and contribute to its growth over the next fifty years.

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 general psychopathology factor (p) from adolescence to adulthood: Exploring the developmental trajectories of p using a multi-method approach

Considerable attention has been directed towards studying co-occurring psychopathology through the lens of a general factor (p-factor). However, the developmental trajectory and stability of the p-factor have yet to be fully understood. The present study examined the explanatory power of dynamic mutualism theory - an alternative framework that suggests the p-factor is a product of lower-level symptom interactions that strengthen throughout development. Data were drawn from a population-based sample of girls (N = 2450) who reported on the severity of internalizing and externalizing problems each year from age 14 to age 21. Predictions of dynamic mutualism were tested using three distinct complementary statistical approaches including: longitudinal bifactor models, random-intercept cross-lagged panel models (RI-CLPMs), and network models. Across methods, study results document preliminary support for mutualistic processes in the development of co-occurring psychopathology (that is captured in p). Findings emphasize the importance of exploring alternative frameworks and methods for better understanding the p-factor and its development.

Associations Between General and Specific Psychopathology Factors and 10-Year Clinically Relevant Outcomes in Adult Swedish Twins and Siblings

Importance

General and specific factors of psychopathology are associated with future adverse outcomes, indicating that they might be useful for identifying individuals at greatest risk. However, it remains unknown if these associations are attributable to confounders that may influence both the psychopathology factors and later outcomes.

Objective

To analyze associations between psychopathology factors and clinically relevant outcomes within family pairs, adjusting for unmeasured confounds by applying co-twin control and sibling comparison designs.

Design, Setting, and Participants

This longitudinal cohort study with a follow-up range of 9 to 13 years included all Swedish twins born from 1959 to 1985 who participated in the Study of Twin Adults: Genes and Environment (60% response rate) and the oldest pair of all Swedish siblings born from 1959 to 1985 per the Multi-Generation Register. Twins were evaluated based on responses to a hierarchical factor model derived using multivariate statistics. Sibling pairs were evaluated based on psychiatric diagnoses per the Swedish National Patient Register. Information on outcome events and prescriptions were derived from the National Patient Register, Prescribed Drug Register, and Crime Register. Baseline assessment was in August 2005, and data were analyzed from January 2022 to February 2023.

Exposures

Hierarchical factor model consisting of 1 general and 4 specific factors fit to 48 psychiatric symptoms on which twin participants self-reported in 2005 and 1 general and 3 specific factors fit to 9 register-based psychiatric diagnoses assigned to sibling participants prior to 2005.

Main Outcomes and Measures

Outcomes consisted of 7 register-based events occurring after 2005, including suicidal behavior, substance overdoses, and criminal suspicion or convictions (data available until the end of 2013), and prescription of antidepressants, antialcohol or antiopioid medication, antipsychotics, and stimulants (data available until the end of 2017).

Results

The study included 32 328 twins (mean [SD] age, 34 [8] years; 16 076 [49.73%] male) and 1 942 106 siblings (mean [SD] age, 34 [7] years; 991 500 [51.05%] male). General psychopathology was significantly associated with all 7 outcomes within sibling pairs (mean within-pair odds ratio [OR], 2.28; 95% CI, 2.19-2.37) and dizygotic twin pairs (within-pairs OR, 1.65; 95% CI, 1.38-1.98) and with 3 outcomes within monozygotic twin pairs (mean within-pairs OR, 1.77; 95% CI, 1.35-2.36). Within sibling pairs, the specific internalizing factor was associated with antidepressant prescriptions (within-pairs OR, 1.65; 95% CI, 1.59-1.71), the specific substance misuse factor was associated prescription of antialcohol and antiopioid medication (within-pairs OR, 2.36; 95% CI, 2.20-2.54), and the specific psychotic factor was associated with antipsychotic medications (within-pairs OR, 1.61; 95% CI, 1.51-1.72). Similar results emerged within twin pairs.

Conclusion and Relevance

In this cohort study, general psychopathology was significantly associated with all 7 outcomes within sibling and dizygotic twin pairs and 3 outcomes within monozygotic twin pairs at 10 years. Within twin and sibling pairs, the specific factors were primarily associated with related outcomes. Several of the associations in this cohort study could not be attributed to unmeasured confounds shared by family members, suggesting that interventions toward broad psychopathology dimensions might help reduce the risk of future clinically relevant events.

Shared genetic influences between depression and conduct disorder in children and adolescents: A systematic review

INTRODUCTION

The co-occurrence between major depression disorder (MDD) and conduct disorder (CD) is common across development and represents a significant risk factor for future psychiatric problems and long-term impairment. Large-scale quantitative genetic studies suggest that the MDD-CD co-occurrence may be partly explained by shared genetic vulnerability factors, in line with transdiagnostic models of psychopathology, but no systematic synthesis of the literature is currently available.

METHODS

We therefore conducted a systematic review of the available genetic literature on the co-occurrence between MDD and CD in children and adolescents. We identified 10 eligible studies, including 5 cross-sectional bivariate/multivariate twin studies, 3 longitudinal bivariate/multivariate twin studies, and 2 latent profile/trajectory twin studies.

RESULTS

Most of the reviewed studies found a strong contribution of shared genetic factors on the covariation between depression and conduct problems, in line with the prominent effect of a common genetic liability across development.

LIMITATIONS

The scientific literature on this psychiatric comorbidity is still limited, as it solely consists of twin studies from high income countries.

CONCLUSION

Considering the joint burden of MDD and CD on youth, families and society worldwide, future studies are needed to better investigate the shared risk processes of these frequently co-occurring conditions, in order to inform new treatments through personalized medicine.

Empirical support for a dual process model of the p-factor: Interaction effects between preschool executive control and preschool negative emotionality on general psychopathology

Recent work indicates that a general factor, often referred to as the p-factor, underlies nearly all forms of psychopathology. Although the criterion validity and utility of this general factor have been well supported, questions remain about the substantive meaning of the p-factor. The purpose of the present longitudinal study was to empirically test the hypothesis that the p-factor reflects dysregulation arising from a combination of high dispositional negative emotionality and low executive control. The current study examined preschool executive control, measured using a battery of 9 developmentally appropriate executive control tasks, as a moderator of the association between preschool negative emotionality and both concurrent and subsequent levels of general psychopathology in preschool and elementary school using a community sample (N = 497). Latent moderated structural equation models demonstrated that preschool executive control significantly moderated the associations between preschool negative emotionality and general psychopathology both in preschool and approximately 5 years later in elementary school. These results suggest that the general factor of psychopathology may reflect dysregulation arising from a tendency to experience high negative affect, without sufficient executive control to effectively down-regulate that affect. This work has important implications for identifying transdiagnostic targets for prevention and intervention efforts, as well as furthering understanding of the substantive meaning and construct validity of the general factor of psychopathology. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The Hierarchical Taxonomy of Psychopathology (HiTOP) in psychiatric practice and research

The Hierarchical Taxonomy of Psychopathology (HiTOP) has emerged out of the quantitative approach to psychiatric nosology. This approach identifies psychopathology constructs based on patterns of co-variation among signs and symptoms. The initial HiTOP model, which was published in 2017, is based on a large literature that spans decades of research. HiTOP is a living model that undergoes revision as new data become available. Here we discuss advantages and practical considerations of using this system in psychiatric practice and research. We especially highlight limitations of HiTOP and ongoing efforts to address them. We describe differences and similarities between HiTOP and existing diagnostic systems. Next, we review the types of evidence that informed development of HiTOP, including populations in which it has been studied and data on its validity. The paper also describes how HiTOP can facilitate research on genetic and environmental causes of psychopathology as well as the search for neurobiologic mechanisms and novel treatments. Furthermore, we consider implications for public health programs and prevention of mental disorders. We also review data on clinical utility and illustrate clinical application of HiTOP. Importantly, the model is based on measures and practices that are already used widely in clinical settings. HiTOP offers a way to organize and formalize these techniques. This model already can contribute to progress in psychiatry and complement traditional nosologies. Moreover, HiTOP seeks to facilitate research on linkages between phenotypes and biological processes, which may enable construction of a system that encompasses both biomarkers and precise clinical description.

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.

On top or underneath: where does the general factor of psychopathology fit within a dimensional model of psychopathology?

BACKGROUND

Dimensional models of psychopathology are increasingly common and there is evidence for the existence of a general dimension of psychopathology ('p'). The existing literature presents two ways to model p: as a bifactor or as a higher-order dimension. Bifactor models typically fit sample data better than higher-order models, and are often selected as better fitting alternatives but there are reasons to be cautious of such an approach to model selection. In this study the bifactor and higher-order models of p were compared in relation to associations with established risk variables for mental illness.

METHODS

A trauma exposed community sample from the United Kingdom (N = 1051) completed self-report measures of 49 symptoms of psychopathology.

RESULTS

A higher-order model with four first-order dimensions (Fear, Distress, Externalising and Thought Disorder) and a higher-order p dimension provided satisfactory model fit, and a bifactor representation provided superior model fit. Bifactor p and higher-order p were highly correlated (r = 0.97) indicating that both parametrisations produce near equivalent general dimensions of psychopathology. Latent variable models including predictor variables showed that the risk variables explained more variance in higher-order p than bifactor p. The higher-order model produced more interpretable associations for the first-order/specific dimensions compared to the bifactor model.

CONCLUSIONS

The higher-order representation of p, as described in the Hierarchical Taxonomy of Psychopathology, appears to be a more appropriate way to conceptualise the general dimension of psychopathology than the bifactor approach. The research and clinical implications of these discrepant ways of modelling p are discussed.

Commentary: Time to reconceptualize ASD? comments on Happe and Frith (2020) and Sonuga-Barke (2020)

Happe and Frith (2020) list seven changes in the concept of autism that have taken place since the 80s when autism became the focus of clinical concerns and research interests. These dramatic changes, supported by additional research results, have not convinced Sonuga-Barke (2020) that a Kuhnian revolution in psychiatric nosology may be at our front door. This commentary will discuss this conclusion, calling on ASD researchers to re-evaluate the benefits of a paradigm shift in the nosology of ASD.

Toward precision therapeutics: general and specific factors differentiate symptom change in depressed adolescents

BACKGROUND

The longitudinal course of multiple symptom domains in adolescents treated for major depression is not known. Revealing the temporal course of general and specific psychopathology factors, including potential differences between psychotherapies, may aid therapeutic decision-making.

METHODS

Participants were adolescents with major depressive disorder (aged 11-17; 75% female; N = 465) who were part of the IMPACT trial, a randomized controlled trial comparing cognitive behavioral therapy, short-term psychoanalytic psychotherapy, and brief psychosocial intervention. Self-reported symptoms at baseline and 6, 12, 36, 52, and 86 weeks postrandomization were analyzed with bifactor modeling.

RESULTS

General psychopathology factor scores decreased across treatment and one-year follow-up. Specific melancholic features and depressive cognitions factors decreased from baseline to 6 weeks. Conduct problems decreased across treatment and follow-up. Anxiety increased by 6 weeks and then reverted to baseline levels. Obsessions-compulsions did not change. Changes in general and specific factors were not significantly different between the three psychotherapies during treatment. During follow-up, however, conduct problems decreased more in brief psychosocial intervention versus cognitive behavioral therapy (1.02, 95% Bayes credible interval 0.25, 1.96), but not versus short-term psychoanalytic psychotherapy.

CONCLUSIONS

The clinical response signature in this trial is best revealed by rapid reductions in depression symptoms and general psychopathology. Protracted improvements in general psychopathology and conduct problems subsequently occur. Psychosocial treatments for adolescent depression have comparable effects on general and specific psychopathology, although a psychoeducational, goal-focused approach may be indicated for youth with comorbid conduct problems.

Multisystemic therapy compared with management as usual for adolescents at risk of offending: the START II RCT

Background

The Systemic Therapy for At Risk Teens (START) trial is a randomised controlled trial of multisystemic therapy (MST) compared with management as usual (MAU). The present study reports on long-term follow-up of the trial (to 60 months).

Objectives

The primary objective was to compare MST and MAU for the proportion of young people in each group with criminal convictions up to 60 months post baseline. Secondary outcomes included group comparisons of psychological and behavioural factors. An economic analysis was carried out to determine the cost-effectiveness of MST compared with MAU. Two qualitative studies were conducted to better understand the subjective experiences of the participants.

Design

Primary outcomes (collected up to 60 months) were collected using a centralised police database. Secondary outcomes were evaluated using self-report questionnaires completed by both young people and parents or carers at the 24-, 36- and 48-month follow-ups. Research assistants were blind to treatment allocation.

Setting

Participants were recruited from participating MST sites in nine areas of England. Secondary outcomes were typically collected within the family home.

Participants

A total of 684 families were recruited into the START trial and allocated randomly to a treatment group. Of these, 487 remained in the second phase of the trial. Young people were aged, on average, 13.8 years at baseline, with 63% male and 37% female.

Interventions

MST is a manualised programme for young people exhibiting antisocial behaviour and their families that uses principles from cognitive–behavioural and family therapy to provide an individualised approach. MAU content was not prespecified, but consisted of the standard care offered to young people who met eligibility for the trial.

Main outcome measures

Young people’s offending was evaluated using the Police National Computer. Secondary measures included validated self-report measures completed by both the young person and their parent or carer. The economic evaluation took a broad perspective and outcomes were assessed in terms of quality-adjusted life-years and offending.

Results

No significant differences were found in the proportion of offending between the groups (hazard ratio 1.03, 95% confidence interval 0.84 to 1.26; p = 0.78). No differences were found between the groups on secondary outcome measures, with a few exceptions that did not hold up consistently across the follow-up period. The economic analysis did not find evidence to support the cost-effectiveness of MST compared with MAU. Outcomes from the qualitative studies suggest that families mostly felt positive about MST, and that MST was associated with greater maturity in young men.

Limitations

Some intended evaluations were not possible to deliver. Selective attrition may have influenced the nature of the sample size. It is also unclear how representative the MAU services were of reality.

Future research

Recommendations are made for the evaluation of MST in populations with more severe behavioural problems, as well as for identifying and testing new moderators.

Conclusions

The results of the second phase of the START trial do not support the long-term superiority of MST to MAU, but elements of the intervention may be adapted successfully.

Trial registration

Current Controlled Trials ISRCTN77132214 and London South-East REC registration number 09/H1102/55.

Funding

This project was funded by the National Institute for Health Research (NIHR) Health Services and Delivery Research programme and will be published in full in Health Services and Delivery Research; Vol. 8, No. 23. See the NIHR Journals Library website for further project information.

Drs. Constantinou and Fonagy Reply

We thank Aristodemou and Fried¹ for their thoughtful comments on our article about changes in the psychopathology bifactor dimensions over a psychosocial intervention.² Aristodemou and Fried expressed concerns over our interpretation of the p factor and our selection of the bifactor model over alternative models. We will address each concern and highlight the issues they raise for the field more broadly.

Common Factors and Interpretation of the p Factor of Psychopathology

One of the most discussed recent topics in psychopathology research is the p factor of mental illness. This single dimension is understood to measure "a person's liability to mental disorder, comorbidity among disorders, persistence of disorders over time, and severity of symptoms."¹ A recent paper by Constantinou et al.² published in the Journal investigated the external validity of the p factor. We commend the authors for the contribution to the literature and want to highlight two points: (1) the interpretation of p as a causal entity, and (2) selection of bifactor models over alternative models for reasons of superior fit.

Editors' Best of 2019

There is, in the content of the Journal, an embarrassment of riches, and picking a "best" seems to demand a certain qualification: is the "best" the most interesting, most surprising, most educational, most important, most provocative, most enjoyable? How to choose? We are hardly unbiased and can admit to a special affection for the ones that we and the authors worked hardest on, hammering version after version into shape. Acknowledging these biases, here are the 2019 articles that we think deserve your attention or at least a second read.

Editorial: Putting Practicality Into "p": Leveraging General Factor Models of Psychopathology in Clinical Intervention

There exists widespread dissatisfaction with current categorical approaches to mental disorders, in particular the DSM,^1,2 along with considerable quantitative empirical evidence that mental disorders are more accurately understood as continuously distributed dimensions of psychopathology. This has resulted in an increasing shift toward a dimensional organization of psychopathology in contemporary psychiatry.³ Factor-analytic modeling of symptom data derived from numerous measures of mental illness and psychopathology has provided consistent evidence for a transdiagnostic general factor model of psychopathology. In the most basic general factor model, classic diagnostic phenotypes, such as anxiety and depression, are thought to be reflected by a specific internalizing psychopathology dimension, whereas conduct and attention/hyperactivity disorders most often are reflected by a specific externalizing psychopathology dimension. In addition, a general psychopathology, or a "p" factor,⁴ reflects both the common variation among all symptoms of psychopathology, as well as low to high psychopathology severity, thus cutting across diverse mental disorder categories. This shared variation reflects the high rates of comorbidity commonly observed across most classic mental disorder categories.

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.