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.

Borderline personality disorder and depression severity predict suicidal outcomes: A six-month prospective cohort study of depression, bipolar depression, and borderline personality disorder.

BACKGROUND: Suicide risk is high in patients with major depressive disorder (MDD), bipolar disorder (BD) and borderline personality disorder (BPD). Whether risk levels of and risk factors for suicidal ideation (SI) and suicide attempts (SA) are similar or different in these disorders remains unclear, as few directly comparative studies exist. The relationship of short-term changes in depression severity and SI is underinvestigated, and might differ across groups, for example, between BPD and non-BPD patients. METHODS: We followed, for 6 months, a cohort of treatment-seeking, major depressive episode (MDE) patients in psychiatric care (original n = 124), stratified into MDE/MDD, MDE/BD and MDE/BPD subcohorts. We examined risks of suicide-related outcomes and their risk factors prospectively. We examined the covariation of SI and depression over time with biweekly online modified Patient Health Questionnaire 9 surveys and analysed this relationship through multi-level modelling. RESULTS: Risk of SA in BPD (22.2%) was higher than non-BPD (4.23%) patients. In regression models, BPD severity was correlated with risk of SA and clinically significant SI. During follow-up, mean depression severity and changes in depression symptoms were associated with SI risk regardless of diagnosis. CONCLUSIONS: Concurrent BPD in depression seems predictive for high risk of SA. Severity of BPD features is relevant for assessing risk of SA and SI in MDE. Changes in depressive symptoms indicate concurrent changes in risk of SI. BPD status at intake can index risk for future SA, whereas depressive symptoms appear a useful continuously monitored risk index.

The Overall Anxiety Severity and Impairment Scale as an Outcome Measure in Internet-Delivered Cognitive Behavioral Therapy for Anxiety Disorders: Observational Study.

BACKGROUND: Internet-delivered cognitive behavioral therapy (iCBT) is effective in the treatment of anxiety disorders. iCBT clinical trials use relatively long and time-consuming disorder-specific rather than transdiagnostic anxiety measurements. Overall Anxiety Severity and Impairment Scale (OASIS) is a brief self-report scale that could offer a universal, easy-to-use anxiety measurement option in disorder-specific and transdiagnostic iCBT programs. OBJECTIVE: We aimed to investigate relationships between OASIS and disorder-specific instruments in iCBT. We expected these relationships to be positive. METHODS: We investigated patients in original nationwide iCBT programs for generalized anxiety disorder (GAD), obsessive-compulsive disorder, panic disorder, and social anxiety disorder, which were administered by Helsinki University Hospital, Finland. In each program, anxiety symptoms were measured using both disorder-specific scales (the 7-item Generalized Anxiety Disorder scale, Penn State Worry Questionnaire, revised Obsessive-Compulsive Inventory, Panic Disorder Severity Scale, and Social Phobia Inventory) and by OASIS. A general linear model for repeated measures (mixed models) and interaction analysis were used for investigating the changes and relationships in the mean scores of OASIS and disorder-specific scales from the first session to the last one. RESULTS: The main effect of linear mixed models indicated a distinct positive association between OASIS and disorder-specific scale scores. Interaction analysis demonstrated relatively stable associations between OASIS and the revised Obsessive-Compulsive Inventory (F822.9=0.09; 95% CI 0.090-0.277; P=.32), and OASIS and the Panic Disorder Severity Scale (F596.6=-0.02; 95% CI -0.108 to -0.065; P=.63) from first the session to the last one, while the 7-item Generalized Anxiety Disorder scale (F4345.8=-0.06; 95% CI -0.109 to -0.017; P=.007), Penn State Worry Questionnaire (F4270.8=-0.52; 95% CI -0.620 to -0.437; P<.001), and Social Phobia Inventory (F862.1=-0.39; 95% CI -0.596 to -0.187; P<.001) interrelated with OASIS more strongly at the last session than at the first one. CONCLUSIONS: OASIS demonstrates clear and relatively stable associations with disorder-specific symptom measures. Thus, OASIS might serve as an outcome measurement instrument for disorder-specific and plausibly transdiagnostic iCBT programs for anxiety disorders in regular clinical practice.

Finnish Psychotherapy Quality Register: rationale, development, and baseline results.

BACKGROUND: The push to systematically follow treatment outcomes in psychotherapies to improve health care is increasing worldwide. To manage psychotherapeutic services and facilitate tailoring of therapy according to feedback a comprehensive and feasible data system is needed. AIMS: To describe the Finnish Psychotherapy Quality Register (FPQR), a comprehensive database on availability, quality, and outcomes of psychotherapies. METHODS: We describe the development of the FPQR and outcome for outsourced psychotherapies for adults in Helsinki and Uusimaa hospital district (HUS). Symptom severity and functioning are measured with validated measures (e.g. CORE-OM, PHQ-9, OASIS, AUDIT, and SOFAS). Questionnaires on therapeutic alliance, risks, methods, and goals are gathered from patients and psychotherapist. RESULTS: During 2018-2021, the FPQR included baseline data for 7274 unique patients and 336 psychotherapists. Response rate of measures was 85-98%. The use of the register was mandatory for the outsourced therapist of the hospital districts, and the patients were strongly recommended to fulfill the questionnaires. We report outcome for three groups of patients (n = 1844) with final/midterm data. The effect sizes for long psychotherapy (Hedge's g = 0.65 of SOFAS) were smaller than those for short psychotherapy (g = 0.75-0.91). Within three months of referral, 26-60% entered treatment depending on short- or long-term therapy. CONCLUSION: The FPQR forms a novel rich database with commensurate data on availability and outcomes of outsourced psychotherapies. It may serve as a basis for a national comprehensive follow-up system of psychosocial treatments. The Finnish system seems to refer patients with milder symptoms to more intensive treatments and achieve poorer results compared to the IAPT model in UK, Norway, or Australia.

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.

Healthcare workers' heterogeneous mental-health responses to prolonging COVID-19 pandemic: a full year of monthly follow up in Finland.

BACKGROUND: The COVID-19 pandemic strained healthcare workers but the individual challenges varied in relation to actual work and changes in work. We investigated changes in healthcare workers' mental health under prolonging COVID-19 pandemic conditions, and heterogeneity in the mental-health trajectories. METHODS: A monthly survey over a full year was conducted for employees of the HUS Helsinki University Hospital (n = 4804) between 4th June 2020 to 28th May 2021. Pandemic-related potentially traumatic events (PTEs), work characteristics (e.g., contact to COVID-19 patients), local COVID-19 incidence, and demographic covariates were used to predict Mental Health Index-5 (MHI-5) and Insomnia Severity Index (ISI) in generalized multilevel and latent-class mixed model regressions. RESULTS: Local COVID-19 log-incidence (odds ratio, OR = 1.21, with 95% CI = 1.10-1.60), directly caring for COVID-19 patients (OR = 1.33, CI = 1.10-1.60) and PTEs (OR = 4.57, CI = 3.85-5.43) were all independently associated with psychological distress, when (additionally) adjusting for age, sex, profession, and calendar time. Effects of COVID-19 incidence on mental health were dissociable from calendar time (i.e., evolved in time) whereas those on sleep were not. Latent mental-health trajectories were characterized by a large class of "stable mental health" (62% of employees) and minority classes for "early shock, improving" (14%) and "early resilience, deteriorating" mental health (24%). The minority classes, especially "early shock, improving", were more likely to live alone and be exposed to PTEs than the others. CONCLUSIONS: Healthcare workers faced changing and heterogeneous mental-health challenges as the COVID-19 pandemic prolonged. Adversity and mental ill-being may have accumulated in some employees, and factors like living arrangements may have played a role. Knowledge on employees' demographic and socioeconomic background, as well as further research on the factors affecting employees' resilience, may help in maintaining healthy and efficient workforce in the face of a prolonging pandemic.

Text Topics and Treatment Response in Internet-Delivered Cognitive Behavioral Therapy for Generalized Anxiety Disorder: Text Mining Study.

BACKGROUND: Text mining methods such as topic modeling can offer valuable information on how and to whom internet-delivered cognitive behavioral therapies (iCBT) work. Although iCBT treatments provide convenient data for topic modeling, it has rarely been used in this context. OBJECTIVE: Our aims were to apply topic modeling to written assignment texts from iCBT for generalized anxiety disorder and explore the resulting topics' associations with treatment response. As predetermining the number of topics presents a considerable challenge in topic modeling, we also aimed to explore a novel method for topic number selection. METHODS: We defined 2 latent Dirichlet allocation (LDA) topic models using a novel data-driven and a more commonly used interpretability-based topic number selection approaches. We used multilevel models to associate the topics with continuous-valued treatment response, defined as the rate of per-session change in GAD-7 sum scores throughout the treatment. RESULTS: Our analyses included 1686 patients. We observed 2 topics that were associated with better than average treatment response: "well-being of family, pets, and loved ones" from the data-driven LDA model (B=-0.10 SD/session/∆topic; 95% CI -016 to -0.03) and "children, family issues" from the interpretability-based model (B=-0.18 SD/session/∆topic; 95% CI -0.31 to -0.05). Two topics were associated with worse treatment response: "monitoring of thoughts and worries" from the data-driven model (B=0.06 SD/session/∆topic; 95% CI 0.01 to 0.11) and "internet therapy" from the interpretability-based model (B=0.27 SD/session/∆topic; 95% CI 0.07 to 0.46). CONCLUSIONS: The 2 LDA models were different in terms of their interpretability and broadness of topics but both contained topics that were associated with treatment response in an interpretable manner. Our work demonstrates that topic modeling is well suited for iCBT research and has potential to expose clinically relevant information in vast text data.

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.

Length of exposure to long working hours and night work and risk of sickness absence: a register-based cohort study.

BACKGROUND: There is inconsistent evidence that long working hours and night work are risk factors for sickness absence, but few studies have considered variation in the length of exposure time window as a potential source of mixed findings. We examined whether the association of long working hours and night work with sickness absence is dependent on the length of exposure to the working hour characteristics. METHODS: We analysed records of working hours, night work and sickness absence for a cohort of 9226 employees in one hospital district in Finland between 2008 and 2019. The exposure time windows ranged from 10 to 180 days, and we used Cox's proportional hazards models with time-dependent exposures to analyse the associations between working-hour characteristics and subsequent sickness absence. RESULTS: Longer working hours for a period of 10 to 30 days was not associated with the risk of sickness absence whereas longer working hours for a period of 40 to 180 days was associated with a lower risk of sickness absence. Irrespective of exposure time window, night work was not associated with sickness absence. CONCLUSIONS: It is important to consider the length of exposure time window when examining associations between long working hours and sickness absence, whereas the association between night work and sickness absence is not similarly sensitive to exposure times.

Effectiveness of brief schema group therapy for borderline personality disorder symptoms: a randomized pilot study.

BACKGROUND AND OBJECTIVES: Schema group therapy is a potentially cost-effective treatment for borderline personality disorder (BPD). We piloted the feasibility and effectiveness of a 20-session schema group therapy without individual therapy among psychiatric BPD outpatients in a randomized pilot study registered as a clinical trial (ISRCTN76381242). METHODS: Altogether 42 psychiatric outpatients diagnosed with BPD were randomized 2:1 to a 20-session weekly schema group therapy plus treatment as usual (TAU) (n = 28) vs. a control group with TAU alone (n = 14). The primary outcome was decline of BPD symptoms in the short Borderline Symptom List (BSL-23) score. Secondary outcomes were decline in symptoms of anxiety, depression, alcohol use, and improvement in functioning and schema modes. Two external experts evaluated validity of the intervention based on videotaped sessions. RESULTS: Overall, 23 schema group therapy patients (82%) and 12 controls (86%) completed their treatment. Treatment validity good or very good. However, no significant differences emerged in the primary outcome mean BSL-23 decline (6.95 [SE 5.91] in group schema therapy vs. 12.55 [4.85] in TAU) or in any of the secondary outcome measures. LIMITATIONS: Despite randomization, the TAU subgroup had non-significantly higher baseline scores in most measures. Small sample size predisposing to type II errors; reliance on self-reported outcomes. CONCLUSIONS: Schema group therapy was feasible for psychiatric outpatients with BPD. However, in this small pilot study we did not find it more effective than TAU. Effectiveness of this short intervention remains open.

Health behaviors and psychological distress: changing associations between 1997 and 2016 in the United States.

OBJECTIVES: Smoking rates have declined with a slower pace among those with psychological distress compared to those without. We examined whether other health behaviors (heavy alcohol consumption, physical inactivity, short sleep duration) showed similar trends associated with psychological distress. We also examined differences by age and birth cohort. METHODS: Data were from the annually repeated cross-sectional U.S. National Health Interview Surveys (NHIS) of 1997-2016 (total n = 603,518). Psychological distress was assessed with the 6-item Kessler Psychological Distress Scale (K6). RESULTS: Psychological distress became more strongly associated with smoking (OR 1.09 per 10 years; 95% CI 1.07, 1.12), physical inactivity (OR 1.08; 1.05, 1.11), and short sleep (OR 1.12; 1.06, 1.18), but less strongly associated with heavy alcohol consumption (OR 0.93; 0.89, 0.98). The associations of smoking and alcohol consumption attenuated with age, whereas the association with physical inactivity strengthened with age. Compared to older birth cohorts, smoking became more strongly associated with psychological distress among younger birth cohorts up to those born in the 1980s. CONCLUSIONS: The strength of associations between psychological distress and health behaviors may vary by time period, age, and birth cohort.

Continuity of genetic and environmental influences on clinically assessed major depression from ages 18 to 45.

BACKGROUND: Studies on the stability of genetic risk for depression have relied on self-reported symptoms rather than diagnoses and/or short follow-up time. Our aim is to determine to what degree genetic and environmental influences on clinically assessed major depressive disorder (MDD) are stable between age 18 and 45. METHODS: A population-based sample of 11 727 twins (6875 women) born between 1967 and 1991 was followed from 2006 to 2015 in health registry data from primary care that included diagnoses provided by treating physicians. Individuals with schizophrenia or bipolar disorder (n = 163) were excluded. We modelled genetic and environmental risk factors for MDD in an accelerated longitudinal design. RESULTS: The best-fitting model indicated that genetic influences on MDD were completely stable from ages 18 to 45 and explained 38% of the variance. At each age, the environmental risk of MDD was determined by the risk at the preceding observation, plus new environmental risk, with an environmental correlation of +0.60 over 2 years. The model indicated no effects of shared environment and no environmental effects stable throughout the observational period. All long-term stability was therefore explained by genetic factors. CONCLUSIONS: Different processes unfolded in the genetic and environmental risk for MDD. The genetic component is stable from later adolescence to middle adulthood and accounted for nearly all long-term stability. Therefore, molecular genetic studies can use age-heterogenous samples when investigating genetic risk variants of MDD. Environmental risk factors were stable over a short span of years with associations rapidly decreasing and no evidence of permanent environmental scarring.

Joint factorial structure of psychopathology and personality.

BACKGROUND: Normative and pathological personality traits have rarely been integrated into a joint large-scale structural analysis with psychiatric disorders, although a recent study suggested they entail a common individual differences continuum. METHODS: We explored the joint factor structure of 11 psychiatric disorders, five personality-disorder trait domains (DSM-5 Section III), and five normative personality trait domains (the 'Big Five') in a population-based sample of 2796 Norwegian twins, aged 19‒46. RESULTS: Three factors could be interpreted: (i) a general risk factor for all psychopathology, (ii) a risk factor specific to internalizing disorders and traits, and (iii) a risk factor specific to externalizing disorders and traits. Heritability estimates for the three risk factor scores were 48% (95% CI 41‒54%), 35% (CI 28‒42%), and 37% (CI 31‒44%), respectively. All 11 disorders had uniform loadings on the general factor (congruence coefficient of 0.991 with uniformity). Ignoring sign and excluding the openness trait, this uniformity of factor loadings held for all the personality trait domains and all disorders (congruence 0.983). CONCLUSIONS: Based on our findings, future research should investigate joint etiologic and transdiagnostic models for normative and pathological personality and other psychopathology.

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

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

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

BACKGROUND: It is unknown whether social anxiety disorder (SAD) has a unique association with alcohol use disorder (AUD) over and beyond that of other anxiety disorders, how the associations develop over time, and whether the associations are likely to be causal. METHODS: Diagnoses of AUD, SAD, generalized anxiety disorder, panic disorder, agoraphobia, and specific phobias were assessed twice using the Composite International Diagnostic Interview among 2,801 adult Norwegian twins. The data were analyzed using logistic regression analyses and multivariate biometric structural equation modeling. RESULTS: SAD had the strongest association with AUD, and SAD predicted AUD over and above the effect of other anxiety disorders. In addition, SAD was prospectively associated with AUD, whereas other anxiety disorders were not. AUD was associated with a slightly elevated risk of later anxiety disorders other than SAD. Biometric modeling favored a model where SAD influenced AUD compared to models where the relationship was reversed or due to correlated risk factors. Positive associations between AUD and other anxiety disorders were fully explained by shared genetic risk factors. CONCLUSIONS: Unlike other anxiety disorders, SAD plausibly has a direct effect on AUD. Interventions aimed at prevention or treatment of SAD may have an additional beneficial effect of preventing AUD, whereas interventions aimed at other anxiety disorders are unlikely to have a similar sequential effect on AUD.

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

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

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

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

Dimensions of the South Oaks Gambling Screen in Finland: A cross-sectional population study.

The underlying structure of problematic gambling behaviors, such as those assessed by the South Oaks Gambling Screen (SOGS), remain unknown: Can problem gambling be assessed unidimensionally or should multiple qualitatively different dimensions be taken into account, and if so, what do these qualitative dimensions indicate? How significant are the deviations from unidimensionality in practice? A cross-sectional random sample of Finns aged 15-74 (n = 4,484) was drawn from the Population Information Registry and surveyed in 2011-2012. Analyses were conducted using descriptive statistics, Confirmatory factor analysis (CFA) and multidimensional item response theory (MIRT) models. Altogether, 14.9% of the population endorsed at least one of the 20 SOGS items, but nine items had low endorsement rates (≤ 0.2%). CFA and MIRT techniques suggested that individuals differed from each other in two positively correlated (r = 0.70) underlying dimensions: "impact on self primarily" and "impact on others also". This two-factor correlated-factors model can be reinterpreted as a bifactor model with one general gambling-problem factor and two specific factors with similar interpretation as in the correlated-factors model but with non-overlapping items. The two specific factors may provide clinically useful information without extra costs of assessment.

Scalar utility theory and proportional processing: What does it actually imply?

Scalar Utility Theory (SUT) is a model used to predict animal and human choice behaviour in the context of reward amount, delay to reward, and variability in these quantities (risk preferences). This article reviews and extends SUT, deriving novel predictions. We show that, contrary to what has been implied in the literature, (1) SUT can predict both risk averse and risk prone behaviour for both reward amounts and delays to reward depending on experimental parameters, (2) SUT implies violations of several concepts of rational behaviour (e.g. it violates strong stochastic transitivity and its equivalents, and leads to probability matching) and (3) SUT can predict, but does not always predict, a linear relationship between risk sensitivity in choices and coefficient of variation in the decision-making experiment. SUT derives from Scalar Expectancy Theory which models uncertainty in behavioural timing using a normal distribution. We show that the above conclusions also hold for other distributions, such as the inverse Gaussian distribution derived from drift-diffusion models. A straightforward way to test the key assumptions of SUT is suggested and possible extensions, future prospects and mechanistic underpinnings are discussed.