Diagnostic features

Prevalence, comorbidity, and natural course

Fawcett2020 - Women are at greater risk of OCD than Men, A Meta-Analytic Review of OCD Prevalence Worldwide

Fullana2009 - Obsessions and Compulsions in the Community, Prevalence, Interference, Help-seeking, Developmental Stability, and Co-Occurring Psychiatric Conditions

Mataix-Cols2002 - Symptom Stability in Adult Obsessive-Compulsive Disorder, Data From a Naturalistic Two-Year Follow-Up Study

Skoog1999 - A 40-Year Follow-up of Patients With Obsessive-compulsive Disorder

Brakoulias2017 - Comorbidity, age of onset and suicidality in obsessive-compulsive disorder (OCD), An international collaboration

Having a lifetime diagnosis of depression, taboo obsessions and a general OCD factor were associated with suicidality in a large cohort of 1000 individuals. - Cervin2022 - Taboo obsessions and their association with suicidality in obsessive-compulsive disorder

OCD has a bimodal onset, with early onset OCD (mean age 13) shows a more severe clinical presentation compared to late onset (mean age 25) of the disorder. – Anholt2014 - Age of onset in obsessive-compulsive disorder, admixture analysis with a large sample

In a large sample of OCD patients (n = 483), a bimodal distribution of age of onset was confirmed, specifically early onset (mean = 18 years) and late onset (mean = 29.5 years) OCD. – Albert2015 - Admixture analysis of age at symptom onset and age at disorder onset in a large sample of patients with obsessive–compulsive disorder

Cederlöf2015 - Etiological overlap between obsessive-compulsive disorder and anorexia nervosa. a longitudinal cohort, multigenerational family and twin study

Comorbidity rates of OCD and eating disorders are higher than what would be expected by chance, and this pattern could be due to shared personality characteristics such as impulsivity and perfectionism. – Altman2009 - What is the association between obsessive-compulsive disorder and eating disorders

Symptoms of OCD and depression influence each other during treatment. - Simkin2022 - The relationship between symptoms of obsessive compulsive disorder and depression during therapy, A random intercept cross-lagged panel model

OCD during the COVID-19 pandemic

Carmi2021 - Obsessive Compulsive Disorder During Coronavirus Disease 2019 (COVID-19), 2- and 6-month Follow-Ups in a Clinical Trial

Guzick2021 - Obsessive-Compulsive Disorder During the COVID-19 Pandemic, a Systematic Review

During the first wave of the COVID-19 pandemic, over 50% of surveyed individuals in Italy reported clinically relevant levels of contamination obsessions and compulsions. - Pacitti2022 - Obsessive-compulsive symptoms among the general population during the first COVID-19 epidemic wave in Italy

Etiology and maintenance of OCD symptoms


Mataix-Cols2013 - Population-Based, Multigenerational Family Clustering Study of Obsessive-Compulsive Disorder

Pettersson2018 - Genetic influences on eight psychiatric disorders based on family data of 4 408 646 full and half-siblings, and genetic data of 333 748 cases and controls

Marees2021 - Genetic correlates of socio-economic status influence the pattern of shared heritability across mental health traits

Mahjani2021 - The Genetic Architecture of Obsessive-Compulsive Disorder, Contribution of Liability to OCD From Alleles Across the Frequency Spectrum

Mahjani2021 - Genetics of obsessive-compulsive disorder

Burton2021 - Genome-wide association study of pediatric obsessive-compulsive traits, shared genetic risk between traits and disorder

den Braber 2016 - Obsessive–compulsive symptoms in a large population-based twin-family sample are predicted by clinically based polygenic scores and by genome-wide SNPs

Smit2020 - Genetic meta-analysis of obsessive-compulsive disorder and self-report obsessive-compulsive symptoms

Heritability OCD = 0.48 (95% CI 0.42 to 0.53). – Monzani2014 - The Structure of Genetic and Environmental Risk Factors for Dimensional Representations of DSM-5 Obsessive-Compulsive Spectrum Disorders

The heritability of OCD has been estimated to 45-58% in large twin-studies. – Hudziak2004 - Genetic and Environmental Contributions to the Child Behavior ChecklistObsessive-Compulsive Scale, A Cross-cultural Twin Study


Heuvel2020 - An overview of the first 5 years of the ENIGMA obsessive-compulsive disorder working group, The power of worldwide collaboration

Posner2017 - Increased Functional Connectivity between the Default Mode and Salience Networks in Unmedicated Adults with Obsessive-Compulsive Disorder

Pauls2014 - Obsessive-compulsive disorder, an integrative genetic and neurobiological perspective

Richter2018 - Obsessive-Compulsive Disorder

Environmental risk factors

Yilmaz2022 - The role of early-life family composition and parental socio-economic status as risk factors for obsessive-compulsive disorder in a Danish national cohort

Brander2016 - Systematic review of environmental risk factors for Obsessive-Compulsive Disorder, A proposed roadmap from association to causation

Brander2016 - Association of Perinatal Risk Factors With Obsessive-Compulsive Disorder, A Population-Based Birth Cohort, Sibling Control Study

No association between cesarean delivery and OCD, and familial confounding explains previous results - Zhang2021 - Assessment of Cesarean Delivery and Neurodevelopmental and Psychiatric Disorders in the Children of a Population-Based Swedish Birth Cohort

Zhang2019 - Association of Cesarean Delivery With Risk of Neurodevelopmental and Psychiatric Disorders in the Offspring, A Systematic Review and Meta-analysis

Retrospective studies with potential recall bias, the role of stress and stressful life events is unclear - Raposo-Lima2020 - The Role of Stress in Obsessive-Compulsive Disorder, A Narrative Review

Animal models

Ahmari2013 - Repeated Corcico-Striatal Stimulation Generates Persistent OCD-Like Behavior Burguiere2013 - Optogenetic Stimulation of Lateral Orbitofronto-Striatal Pathway Suppresses Compulsive Behaviors Dangelo2014 - Animal models of obsessive-compulsive spectrum disorders Remier2017 - Fear extinction in an obsessive-compulsive disorder animal model - influence of sex and estrous cycle

Habit theory

Dolan2013 - Goals and Habits in the Brain Dougherty2018 - Neuroscientifically Informed Formulation and Treatment Planning for Patients with Obsessive-Compulsive Disorder - A Review Gillan2014 - Goal-directed learning and obsessive-compulsive disorder Gillan2015 - Functional Neuroimaging of Avoidance Habits in Obsessive-Compulsive Disorder Vaghi2017 - Hypoactivation and Dysconnectivity of a Frontostriatal Circuit During Goal-Directed Planning as an Endophenotype for Obsessive-Compulsive Disorder Voon2014 - Disorders of compulsivity - A common bias towards learning habits Voon2015 - Motivation and value influences in the relative balance of goal-directed and habitual behaviours in obsessive-compulsive disorder

Psychological explanations

  • Inflated personal responsibility and the overestimation of threat
  • Perfectionism and intolerance of uncertainty
  • Over-importance of one’s thoughts and need to control thoughts


Rachman1997 - A cognitive theory of obsessions Rachman1998 - A cognitive theory of obsessions - elaborations Andersson2015 - Testing the Mediating Effects of Obsessive Beliefs in Internet-Based Cognitive Behaviour Therapy for Obsessive-Compulsive Disorder Salkovskis1985 - Obsessional Compulsive Problems A Cognitive-Behavioural Analysis Thought-action fusion Ren2021 - Executive Functioning in Chinese Patients With Obsessive Compulsive Disorder Radomsky2022 - Responsibility, probability, and severity of harm, An experimental investigation of cognitive factors associated with checking-related OCD

Network theory

Olatunji2019 - What is at the core of OCD, A network analysis of selected obsessive-compulsive symptoms and beliefs

Responders and non-responders to intensive ERP differed in their response to emotional distress

Computational model

Compulsions can be both attempts to reduce overestimated threat, and expressions of inflexible habits. Both proximal causes stem from the same core impairment (unreliable predictive models) and differentiating them becomes a question of context (e.g., some contexts encourage habit formation more than others), rather than a theoretical stance.

Treatment of OCD

Pharmacological treatments

8 patients received Ketamine, 50% responded at 1-week follow-up - Rodriguez2013 - Randomized Controlled Crossover Trial of Ketamine in Obsessive-Compulsive Disorder, Proof-of-Concept

Ketamine + 10 sessions EX/RP (n = 8), 63% responded - Rodriguez2016 - Can Exposure-Based CBT Extend IV Ketamine’s Effects in Obsessive-Compulsive Disorder, An Open-Label Trial

Psychological treatments

Mindfulness not better than control conditions on the Y-BOCS - Chien2022 - Is mindfulness-based intervention an effective treatment for people with obsessive-compulsive disorder, A systematic review and meta-analysis

A recent study concluded that patients who benefit from ERP can safely discontinue medication with an SSRI with non-inferior outcomes compared to patients who continue their SSRI - Foa2022 - Maintenance of Wellness in Patients With Obsessive-Compulsive Disorder Who Discontinue Medication After Exposure Response Prevention Augmentation, A Randomized Clinical Trial


Improved adherence and trt completion with therapist-guidance: Musiat2022 - Impact of guidance on intervention adherence in computerised interventions for mental health problems, a meta-analysis

ICBT RCT from Japan: Matsumoto2022 - Guided internet-based cognitive behavioral therapy for obsessive-compulsive disorder, A multicenter randomized controlled trial in Japan

App and video treatment

In a large naturalistic sample (n = 3552), ERP delivered via video and supported by an app in between sessions resulted in large reductions on the dimensional Y-BOCS (g = 1.0 [95% CI 0.93 to 1.03]) [@feusner2022]: Feusner2022 - Online Video Teletherapy Treatment of Obsessive-Compulsive Disorder Using Exposure and Response Prevention, Clinical Outcomes From a Retrospective Longitudinal Observational Study

Gershkovich2021 - Integrating Exposure and Response Prevention With a Mobile App to Treat Obsessive-Compulsive Disorder, Feasibility, Acceptability, and Preliminary Effects

Boisseau2017 - App-guided exposure and response prevention for obsessive compulsive disorder, an open pilot trial

Combination treatment


EX/RP better than risperidone as augmentation of SRIs - Simpson2013 - Cognitive-Behavioral Therapy vs Risperidone for Augmenting Serotonin Reuptake Inhibitors in Obsessive-Compulsive Disorder, A Randomized Clinical Trial



McDougle1995 - A case-controlled study of repetitive thoughts and behavior in adults with autistic disorder and obsessive-compulsive disorder

Murray2015 - Outcomes of cognitive behaviour therapy for obsessive-compulsive disorder in young people with and without autism spectrum disorders A case controlled study

Neil2014 - Assessment and Treatment of Obsessions and Compulsions in Individuals with Autism Spectrum Disorders - a Systematic Review

Russell2005 - Obsessions and compulsions in autistic-spectrum disorders

Russell2009 - Psychological treatment for obsessive-compulsive disorder in people with autism spectrum disorders - a pilot study

Russell2013 - Cognitive behavior therapy for comorbid obsessive-compulsive disorder in high-functioning autism spectrum disorders - a randomized controlled trial

Flygare2020 - Adapted cognitive behavior therapy for obsessive-compulsive disorder with co-occurring autism spectrum disorder, A clinical effectiveness study

The initial results of an internet-delivered adapted CBT for OCD in youth with co-occurring ASD has shown encouraging results (within-group effect size d = 1.33) [@wickberg2022] - Wickberg2022 - Feasibility of ICBT for OCD in youth with ASD, A clinical benchmark study

Vause2015 - Preliminary Randomized Trial of Function-Based Cognitive-Behavioral Therapy to Treat Obsessive Compulsive Behavior in Children With Autism Spectrum Disorder

Wakabayashi2012 - Do the traits of autism-spectrum overlap with those of schizophrenia or obsessive-compulsive disorder in the general population

Current issues in the treatment of OCD


Mataix-Cols2016 - Towards an international expert consensus for defining treatment response, remission, recovery and relapse in obsessive-compulsive disorder


Abramovitch2020 - Severity benchmarks and contemporary clinical norms for the Obsessive-Compulsive Inventory-Revised (OCI-R)

Abramowitz2005 - Measuring Change in OCD - Sensitivity of the Obsessive-Compulsive Inventory-Revised

Foa2002 - The Obsessive-Compulsive Inventory - Development and validation of a short version

Abramowitz2006 - Psychometric properties and construct validity of the Obsessive-Compulsive Inventory-Revised, Replication and extension with a clinical sample

Huppert2007 - The OCI-R, Validation of the subscales in a clinical sample

Veale2016 - Sensitivity to change in the Obsessive Compulsive Inventory, Comparing the standard and revised versions in two cohorts of different severity

A shorter version of the OCI-R, the OCI-12, excludes the hoarding and neutralizing subscales and has similar psychometric properties compared to the full OCI-R scale [@abramovitch2021a] : Abramovitch2021 - The OCI-12, A syndromally valid modification of the obsessive-compulsive inventory-revised


Original paper for YBOCS. interrater reliability r = 0.98, Cronbach’s alpha = 0.89 Goodman1989 - The Yale-Brown Obsessive Compulsive Scale

Interrater ICC = 0.93, Cronbach’s alpha = 0.69 (resistance to obs/comp pulls down consistency metric, items 4 & 9) Woody1995 - Reliability and Validity of the Yale-Brown Obsessive-Compulsive Scale

YBOCS: subclinical 0-13, mild 14-21, moderate 22-29, severe 30-40 Cervin2022 - Empirical severity benchmarks for obsessive-compulsive disorder across the lifespan

Y-BOCS cut-off response ≥35%, remission ≤14 Farris2013 - Treatment Response, Symptom Remission, and Wellness in Obsessive-Compulsive Disorder