12-month follow-up of intensive outpatient treatment for PTSD combining prolonged exposure therapy, EMDR and physical activity.

BACKGROUND: Preliminary evidence shows promising treatment outcomes at short-term follow-up for intensive posttraumatic stress disorder (PTSD) treatment, but long-term follow-up studies are sparse. This study is a sequel to a previous pilot study and open trial, set out to investigate treatment outcomes at 12-month follow-up for outpatients completing an 8-day intensive treatment for PTSD. METHODS: All patients were diagnosed with PTSD and had multiple previous psychotherapy attempts (M = 3.1). Patients were assessed at pre-treatment, post-treatment, 3- and 12-month follow-up. Of 35 treated patients, 32 (91.4%) attended the long-term follow-up assessment. The treatment programme combined prolonged exposure therapy, eye movement desensitization and reprocessing, and physical activity. RESULTS: The effect sizes indicated large reductions in symptoms of PTSD, depression, anxiety, interpersonal problems, and well-being. Changes in functioning showed a small-medium effect. Results were stable across the follow-up period. The treatment response rates showed that 46-60% of patients achieved recovery with respect to PTSD symptoms, and that 44-48% no longer met diagnostic criteria for PTSD. CONCLUSIONS: Time-limited and concentrated outpatient treatment for PTSD can yield large and enduring positive outcomes. Controlled trials are needed to establish relative efficacy. TRIAL REGISTRATION: The study was registered in Current Research Information System In Norway (Cristin). Cristin-project-ID: 654,790. Date of registration: 18.03.2019.

Patient adherence as a predictor of acute and long-term outcomes in concentrated exposure treatment for difficult-to-treat obsessive-compulsive disorder.

BACKGROUND: Exposure and response prevention (ERP) is considered the first-line psychotherapy for obsessive-compulsive disorder (OCD). Substantial research supports the effectiveness of ERP, yet a notable portion of patients do not fully respond while others experience relapse. Understanding poor outcomes such as these necessitates further research. This study investigated the role of patient adherence to ERP tasks in concentrated exposure treatment (cET) in a sample who had previously not responded to treatment or relapsed. METHOD: The present study included 163 adults with difficult-to-treat OCD. All patients received cET delivered during four consecutive days. Patients' treatment adherence was assessed using the Patient EX/RP Adherence Scale (PEAS-P) after the second and third day of treatment. OCD severity was evaluated at post-treatment, 3-month follow-up, and 1-year follow-up by independent evaluators. RESULTS: PEAS-P scores during concentrated treatment were associated with OCD-severity at post-treatment, 3-month follow-up, and 1-year follow-up. Moreover, PEAS-P scores predicted 12-month OCD severity adjusting for relevant covariates. Adherence also predicted work- and social functioning at 1-year follow-up. CONCLUSIONS: These results indicate that ERP adherence during the brief period of cET robustly relates to improvement in OCD symptoms and functioning in both the short and long term. Assessing adherence might identify patients at risk of poor outcomes, while improving adherence may enhance ERP for treatment resistant patients. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02656342.

The Bergen 4-day treatment for social anxiety disorder: a pilot study.

BACKGROUND: Few studies have examined the use of concentrated and intensified cognitive behaviour therapy for treating social anxiety disorder (SAD). The aim of this study was to examine the feasibility of the Bergen 4-Day Treatment (B4DT) for treating SAD. METHODS: This study adopted an open trial design without a control group. Thirty consecutively referred patients who were diagnosed with SAD were treated and assessed at pre-treatment, at post-treatment, and at the 3-month follow-up. The Liebowitz Social Anxiety Scale was used to assess symptoms of SAD; the Generalized Anxiety Disorder-7 scale was used to assess anxiety symptoms; and the Patient Health Questionnaire-9 was used to assess symptoms of anxiety and depression. The Client Satisfaction Questionnaire-8 was administered posttreatment. RESULTS: Overall, patients reported a high level of satisfaction with the B4DT. Large effect sizes were observed for symptoms of SAD (d = 1.94-2.66) and for the secondary outcomes, i.e., generalized anxiety (d = 0.86-0.99) and depression (d = 0.62-0.83). The remission rate was 55.2% at follow-up, while the treatment response rate was 89.7%. CONCLUSIONS: The B4DT is a promising treatment approach for patients with SAD. In the future, controlled trials should be performed to compare the efficacy of this treatment approach with standard outpatient treatment. Practical consequences, policy implications, and suggestions for future research are discussed herein.

Patient motivation and adherence in metacognitive therapy for major depressive disorder: an observational study.

The aim of this observational study was to examine the predictive and discriminant validity of patient motivation and adherence in metacognitive therapy (MCT) for depression. Motivational development for recovered- and non-recovered patients was also investigated. Motivation in sessions 1, 4, and 7 was measured using the Motivational Interviewing Skill Code 2.5 (MISC) in a 10-session trial of MCT for depression (N = 37). Adherence was assessed with the CBT compliance measure in session 7. The Beck Depression Inventory measured treatment outcome at 3-year follow-up. Recovered patients developed significantly more change talk and taking steps, and less sustain talk, as therapy progressed, compared to non-recovered patients. Evidence of the predictive validity of motivation in sessions 1 and 4 was limited. Higher sustain talk and taking steps in session 7 were significant predictors of more and less depressive symptoms, respectively. There was a moderate-strong correlation between motivation and adherence. The results confirm the predictive value of MISC in sessions 7 of MCT for depression, and establish differential motivational development between recovered and non-recovered patients. Subsequent research should clarify the discriminant validity and temporal relationships between motivation, adherence, and other clinical variables.

Clinically representative therapy for Nordic adult outpatients with common mental health problems: A systematic review and meta-analysis.

There is a knowledge gap regarding clinically representative therapy given in routine settings, that is treatment as usual (TAU), for patients with common mental health problems (CMHP). This review and meta-analysis aimed to investigate what characterizes clinically representative therapy in Nordic routine clinics and meta-analyze the outcome of such treatment. Databases (PubMed, EMBASE, PsychINFO, and SveMed+) were searched for TAU, CMHP, and Nordic countries, together with backward and forward search in Scopus (7 November 2022). Studies were either randomized controlled trials (RCT) or open trials, using prospective study designs, examining heterogeneous outpatient groups in routine treatment. Within- and between-group effect sizes (ES), using random effects model, and moderator analyses were calculated. Eleven studies (n = 1,413), demonstrated a small to moderate within-group ES with high heterogeneity (g = 0.49, I2 = 90%). ESs in RCTs were significantly smaller than in open trials. TAU had a marginally smaller ES (g = -0.21; adjusted for publication bias g = -0.06) compared to a broad set of clinical interventions. Clinically representative therapy in the Nordic countries demonstrated a wide variety of characteristics and also a marginally lower ES compared to other interventions. The ESs were smaller than other meta-analyses examining evidence-based treatments in routine treatment.

Sociodemographic factors and use of pain medication are associated with health-related quality of life: results from an adult community mental health service in Norway.

PURPOSE: Health-related quality of life (HRQoL) is an important aspect of mental health outcomes. There are few studies on HRQoL in heterogeneous patient populations seeking help at community mental health services. The aims of the study were to compare how HRQoL, measured by the EuroQol five dimensions with five levels (EQ-5D-5L), was distributed compared to other samples from national and international studies, and to explore what factors are associated with HRQoL. METHODS: In a cross-sectional study, 1379 Norwegian outpatients reported their HRQoL before starting treatment. Associations with demographic variables, job status, socio-economic status, and use of pain medication were examined using multiple regression analysis. RESULTS: Most of the sample, 70% to 90%, reported problems with usual activities, pain/discomfort, and anxiety/depression; 30% to 65% reported that these problems were of a moderate to extreme degree. Forty percent reported problems with mobility, and about 20% reported problems with self-care. The sample's HRQoL was considerably lower than the general population, and comparable to patient-groups from specialist mental health services. Originating from a developing country, lower level of education, lower yearly household income, being on sick leave or unemployed, and using pain medication were associated with lower HRQoL. Age, gender, and relationship status were not associated with HRQoL. This is the first study to simultaneously examine the unique contribution of these variables in one study. CONCLUSION: The most impacted domains of HRQoL were pain/discomfort, anxiety/depression, and usual activities. Lower HRQoL was associated with several socio-demographic factors and use of pain medication. These findings might have clinical implications and suggest that mental health professionals should routinely measure HRQoL in addition to symptom severity, to identify areas that should be targeted to improve HRQoL.

Symptoms and prevalence of common mental disorders in a heterogenous outpatient sample: an investigation of clinical characteristics and latent subgroups.

BACKGROUND: Patient-reported outcome measures (PROM) provide clinicians with information about patients' perceptions of distress. When linked with treatment and diagnostic registers, new information on common mental health disorders (CMHD) and service use, may be obtained, which might be useful clinically and for policy decision-making. This study reports the prevalence of CMHD and their association with PROM severity. Further, subgroups of self-reported symptoms of depression and anxiety were examined, and their association with clinician-assessed mental disorders, functional impairment, and service use. METHODS: In a cohort study of 2473 (63% female) outpatients, CMHD was examined with pre-treatment scores of self-reported depression and anxiety, and the number of assessments and psychotherapy appointments one year after treatment start. Factor mixture modelling (FMM) of anxiety and depression was used to examine latent subgroups. RESULTS: Overall, 22% of patients with a CMHD had an additional comorbid mood/anxiety disorder, making the prevalence lower than expected. This comorbid group reported higher symptoms of anxiety and depression compared to patients with non-comorbid disorders. FMM revealed three classes: "anxiety and somatic depression" (33%), "mixed depression and anxiety" (40%), and "cognitive depression" (27%). The anxiety and somatic depression class was associated with older age, being single and on sick leave, higher probability of depressive-, anxiety-, and comorbid disorders, having more appointments and higher functional impairment. Although the cognitive depression class had less somatic distress than the mixed depression and anxiety class, they reported more functional impairment and had higher service use. CONCLUSION: The results show that higher levels of somatic symptoms of depression could both indicate higher and lower levels of functional impairment and service use. A group of patients with high somatic depression and anxiety was identified, with severe impairment and high service needs. By gaining insights into CMHD factors' relation with clinical covariates, self-reported risk factors of depression and anxiety could be identified for groups with different levels of aggravating life circumstances, with corresponding service needs. These could be important symptom targets in different groups of patients.

The Bergen 4-day treatment for panic disorder: implementation in a rural clinical setting.

INTRODUCTION: The Bergen 4-Day Treatment (B4DT) is a concentrated treatment with individually tailored exposure exercises. The format has shown promising results in the treatment of panic disorder. AIM: The aim of the current study was to investigate the effectiveness of the B4DT in a large sample in a rural clinical setting. METHOD: Fifty-eight patients with panic disorder were consecutively included using an open trial design. The primary outcome measure was the Panic Disorder Severity Scale. The Generalized Anxiety Disorder-7 and the Patient Health Questionnaire-9 were used as secondary outcome measures. Assessments were conducted at pretreatment, posttreatment, and 3-month follow-up. Treatment satisfaction was measured at posttreatment using the Client Satisfaction Questionnaire-8. RESULTS: There was a significant reduction in symptoms of panic disorder from pre- to posttreatment (d = 3.36) and from pretreatment to follow-up (d = 3.63). At posttreatment and follow-up, 72.4% and 81.0% of patients, respectively, were classified as in remission. Patients reported high treatment satisfaction, and there were significant reductions in symptoms of generalized anxiety and depression. CONCLUSION: The results from the current study replicated the findings from previous studies using a larger sample size. The findings indicate that the B4DT is a promising treatment format for panic disorder. The study also demonstrated that the treatment format can be successfully implemented in new rural clinics.

Validity of the Behavioural Assessment of the Dysexecutive Syndrome for Children (BADS-C) in children and adolescents with pediatric acquired brain injury.

The Behavioural Assessment of the Dysexecutive Syndrome for Children (BADS-C) was developed to address the need for a standardized ecologically valid test of executive function (EF) in the pediatric population. Our study aimed to investigate the discriminant, concurrent, and ecological validity of BADS-C in a sample with pediatric acquired brain injury (pABI). Seventy-four participants with pABI aged 10-17 years were included to a pre-registered randomized controlled trial, and baseline assessment was used for the current study. Controls consisted of 60 participants aged 10-17 years. Participants with pABI were assessed with neuropsychological tests and questionnaires of EF, and measurements of general intellectual ability (IQ). Results showed that all BADS-C subtests discriminated between participants with pABI and controls, except for the Playing Cards Test. Concurrent and ecological validity was demonstrated through associations between BADS-C total score, Key Search Test, and Zoo Map Test 1, and neuropsychological tests and teacher questionnaire ratings of EF. Key Search Test and Zoo Map Test 1 predicted teacher ratings of EF, beyond IQ and other neuropsychological test of EF. These findings provide support for BADS-C as a valid clinical assessment tool that can detect everyday executive dysfunction in the pABI population, and guide rehabilitation and treatment decisions.

Exploring associations between the Modular Assessment of Risk for Imminent Suicide (MARIS) questionnaire and recent suicidal ideation and behavior among patients admitted at an acute psychiatric inpatient department.

PURPOSE: The aim of the present study was to investigate the psychometric validity of the Modular Assessment of Risk for Imminent Suicide (MARIS) questionnaire in relation to recent suicidal ideation and behavior among a sample of patients admitted to an acute psychiatric inpatient department in Norway. METHODS: The MARIS was completed within the first 24 h after admission by 338 patients and their clinicians. Information on recent suicidal ideation and behavior was extracted from patients' medical charts. Two out of four MARIS modules, the Suicide Trigger Scale Short-Form (STS-SF; modified version), and the Therapist Response Questionnaire Short-Form (TRQ-SF) demonstrated good internal consistency. The relationships between the STS-SF, addressing symptoms of the suicide crisis syndrome, and the TRQ-SF, exploring therapist emotional responses, and recent suicidal ideation was investigated by logistic regression analysis. RESULTS: In the logistic regression analysis including pre-selected diagnoses, age, and gender as covariates, both STS-SF and TRQ-SF showed significant associations with recent suicidal ideation (inclusive of suicidal behavior in 27% of the patients with suicidal ideation). CONCLUSION: Both the STS-SF and the TRQ-SF showed concurrent and incremental validity with regard to suicidal ideation. This is the first study showing the cross-cultural validity of the MARIS and supports its clinical utility as a suicide risk assessment tool in inpatient settings. Additionally, this study adds to the literature supporting the value of assessing clinicians' emotional responses to high risk patients.

Factor structure, measurement invariance, and concurrent validity of the Patient Health Questionnaire-9 and the Generalized Anxiety Disorder scale-7 in a Norwegian psychiatric outpatient sample.

OBJECTIVE: The aim of this study was to test factor structure, measurement invariance, and concurrent validity of the nine item Patient Health Questionnaire-9 (PHQ-9) and the seven item Generalized Anxiety Disorder scale-7 (GAD-7) in a heterogeneous outpatient sample. METHOD: Outpatients completed the PHQ-9, GAD-7, and the Working Social Adjustment Scale (WSAS) before starting treatment. Study design was cross-sectional, with convenience sampling. The total sample consisted of 831 participants (61% women). RESULTS: Both PHQ-9 and GAD-7 demonstrated better fit statistics with two-factor and bifactor solutions consisting of a cognitive and somatic factor. Omega hierarchical was .78 for PHQ-9 and .81 for GAD-7. Both instruments achieved scalar invariance across gender, diagnosis, and comorbidity. However, the somatic factors demonstrated poor discriminant validity. These factors are not well separatable and risks being too similar if used together. The general factors of both instruments were most associated with functional impairment, although PHQ-9 demonstrated a stronger association with WSAS (γ = .74, r2 = .62) than GAD-7 (γ = .54, r2 = .32). Using latent mean difference, women and patients with comorbidity had significantly higher scores of both depression and anxiety. CONCLUSION: This study shows that the PHQ-9 and GAD-7 may be used as one-dimensional instruments in clinical settings. Tests for measurement invariance supported that both measures are understood and interpreted comparably across gender and diagnostic subgroups.

The Bergen 4-day treatment for panic disorder: replication and implementation in a new clinic.

BACKGROUND: Bergen 4-day treatment (B4DT) is a concentrated exposure-based treatment (cET), where the patient receives concentrated, individually tailored cognitive behavioral therapy (CBT) during four consecutive days. Previous findings have indicated that B4DT could be a promising treatment for panic disorder (PD). AIM: The aim of the present study was to evaluate the implementation of B4DT for panic disorder with- and without agoraphobia, at a new clinic. This is the first replication study for B4DT on panic disorder. METHOD: Thirty consecutively recruited patients with PD were included in an open trial design. Assessment of symptoms of panic disorder were measured with Panic Disorder Severity Scale (PDSS), while symptoms of generalized anxiety were assessed by Generalized Anxiety Disorder-7 (GAD-7) and depressive symptoms by Patient Health Questionnaire (PHQ-9) pre-treatment, post-treatment and at 3-month follow-up. Treatment satisfaction was measured with Client Satisfaction Questionnaire (CSQ-8) post-treatment. RESULTS: The results showed a significant reduction in symptom severity from pre-treatment to post-treatment (d = 4.32), and at 3-month follow-up (d = 4.91). The proportion of patients classified as fulfilling the criteria for remission was 80.0% at post-treatment and 86.7% at follow up. There was a significant reduction in symptoms of depression and generalized anxiety. Treatment satisfaction was high and none of the patients dropped out. CONCLUSION: The current study replicated the results from the original study and indicate that the treatment can be successfully implemented at new clinics. B4DT may be a promising treatment for panic disorder and comorbid symptoms of generalized anxiety and depression. Larger and more controlled studies are needed to establish the efficacy of B4DT for panic disorder.

Personality traits and hardiness as risk- and protective factors for mental distress during the COVID-19 pandemic: a Norwegian two-wave study.

BACKGROUND: Several risk factors for anxious-depressive symptomatology during the COVID-19 pandemic have been established. However, few studies have examined the relationship between personality traits, hardiness, and such symptomatology during the pandemic. These constructs might serve as risk- and/or protective factors for such mental distress through the pandemic. METHODS: A sample of 5783 Norwegians responded to a survey at two time points within the first year of the pandemic. The first data collection was in April 2020 (T1) and the second in December 2020 (T2). Measures included the Ten-Item Personality-Inventory, the Revised Norwegian Dispositional Resilience Scale, and the Patient Health Questionnaire Anxiety and Depression Scale. Analyses were performed using Pearson's correlations, multiple linear regression, and a moderation analysis. RESULTS: Anxious-depressive symptomatology in early phases (T1) of the pandemic was the strongest predictor for the presence of such symptomatology 9 months after the outbreak (T2). Personality and hardiness correlated significantly with mental distress at T1 and T2. Personality traits explained 5% variance in symptoms when controlling for age, gender, solitary living, negative economic impact, and mental distress at baseline. Higher neuroticism predicted higher mental distress, whereas higher conscientiousness and extraversion predicted less mental distress. Hardiness did not explain variance in outcome beyond personality traits. Hardiness did not significantly moderate the relationship between neuroticism and mental distress. CONCLUSION: Individuals with high levels of neuroticism had greater difficulties adapting to the circumstances of the COVID-19 pandemic and were more prone to mental distress. Contrastingly, higher conscientiousness and extraversion may have served as protective factors for mental distress during the pandemic. The current findings might aid identification of vulnerable individuals and groups. Consequently, preventive interventions could be offered to those who need it the most.

Mental health symptoms during the first months of the COVID-19 outbreak in Norway: A cross-sectional survey study.

BACKGROUND: The COVID-19 pandemic has led to major social and economic changes that could impact public mental health. The main aim of the current study was to investigate mental health in Norway during the COVID-19 outbreak (since the first confirmed case on 26 February 2020). METHODS: The results are from the first wave of the data collection (1 April-2 June 2020), which took place during the outbreak along with its initial restrictions. A total of 19,372 (11,883 students) people participated in a cross-sectional web-based survey. RESULTS: A total of 21.8% scored above the cut-off for depression and 23.7% for anxiety. Severity of symptoms was associated with the accumulation of risk factors, such as possible/confirmed infection for oneself or one's family, female/other sex, students, having mental health problems, increased use of tobacco, increased use of alcohol, less exercise, losing one's job, suffering economic impact and lower education. CONCLUSIONS: COVID-19 could have a negative association with public mental health, especially for certain risk groups. Future data-collection waves will provide further insight into the development of symptoms following the pandemic.

Non-disclosure of suicidal ideation in psychiatric inpatients: Rates and correlates.

The study explored how common non-disclosure of suicidal ideation is in a sample of adult psychiatric inpatients (N = 171) plus associated patient characteristics. A large percentage (51.5%) withheld some information on suicidal ideation during admission. In multivariable analyses, correlates of non-disclosure included a diagnosis of emotionally unstable personality disorder, low satisfaction with stay, and symptoms of the suicide crisis syndrome. In univariate analyses, therapists' emotional response to the patient was also a correlate. Findings indicate that among acute psychiatric inpatients, non-disclosure of suicidal ideation is quite common, requiring awareness from clinicians relying on this parameter in suicide risk assessments.

Patient motivation in group metacognitive therapy for generalized anxiety disorder.

OBJECTIVE: The aim of this study was to investigate the predictive value of motivational language (change talk [CT] and sustain talk [ST]) on treatment outcome of group metacognitive therapy (g-MCT) for generalized anxiety disorder (GAD). METHOD: Video recordings of the first, fourth, and seventh therapy sessions (55 patients) were encoded using the Motivational Interviewing Skill Code (MISC) manual. The strength of the patients' motivational utterances was encoded as CT or ST with seven subcategories. RESULTS: The strength of CT-utterances and ST-utterances differed significantly between treatment responders and non-responders as therapy progressed. The strength of ST-utterances increased significantly more among non-responders than responders, whereas CT and positive taking steps utterances increased more among treatment responders than non-responders. CT and ST in session 1 were not associated with treatment outcome. CT and ST in sessions 4 and 7 significantly predicted lower and higher worry-scores at post-treatment, respectively. This effect was particularly evident for taking steps utterances in session 7. CONCLUSION: These findings confirm the predictive value of MISC in sessions 4 and 7 of g-MCT for GAD and highlight the importance of therapists addressing patient motivation.

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.

Validity of a Norwegian version of the Desire Thinking Questionnaire (DTQ): Associations with problem drinking, nicotine dependence and problematic social media use.

The aim of the current study was to test the validity of the Norwegian version of the Desire Thinking Questionnaire (DTQ). Three cross-sectional surveys were conducted investigating the psychometric properties of the DTQ in alcohol use (N = 588), nicotine use (N = 446) and social media use (N = 359). Principal components and confirmatory factor analyses supported the original two-factor solution consisting of verbal perseveration (VP) and imaginal prefiguration (IP); however, one item was removed to obtain good fit. Internal consistency was acceptable. Both IP and VP showed significant correlations with problem drinking, nicotine dependence and problematic social media use. Regression analyses, controlling for demographics and negative affect, found IP and VP to be significantly associated with all dependent variables. The results confirm that desire thinking is an important construct across different addictive behaviours.

Nordic OCD & Related Disorders Consortium: Rationale, design, and methods.

Obsessive-compulsive disorder (OCD) is a debilitating psychiatric disorder, yet its etiology is unknown and treatment outcomes could be improved if biological targets could be identified. Unfortunately, genetic findings for OCD are lagging behind other psychiatric disorders. Thus, there is a pressing need to understand the causal mechanisms implicated in OCD in order to improve clinical outcomes and to reduce morbidity and societal costs. Specifically, there is a need for a large-scale, etiologically informative genetic study integrating genetic and environmental factors that presumably interact to cause the condition. The Nordic countries provide fertile ground for such a study, given their detailed population registers, national healthcare systems and active specialist clinics for OCD. We thus formed the Nordic OCD and Related Disorders Consortium (NORDiC, www.crowleylab.org/nordic), and with the support of NIMH and the Swedish Research Council, have begun to collect a large, richly phenotyped and genotyped sample of OCD cases. Our specific aims are geared toward answering a number of key questions regarding the biology, etiology, and treatment of OCD. This article describes and discusses the rationale, design, and methodology of NORDiC, including details on clinical measures and planned genomic analyses.