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Obsessive-Compulsive
Disorder (OCD)

A chronic condition characterized by intrusive, unwanted thoughts (obsessions) and repetitive behaviors or mental acts (compulsions) performed to reduce distress.

  • 2-3%
    Prevalence
  • ~19
    Onset Age
  • ~1.6:1
    Ratio
  • ~60%
    Response Rate

DSM-5-TR Diagnostic Criteria

  • Obsessions

    Intrusive and unwanted thoughts

    • • Recurrent, persistent thoughts, urges, or images experienced as intrusive and unwanted
    • • Person attempts to ignore, suppress, or neutralize with another thought or action

  • Compulsions

    Repetitive behaviors or mental acts

    • • Repetitive behaviors or mental acts performed in response to obsessions
    • • Aimed at preventing or reducing distress, but not connected realistically or clearly excessive

  • Additional Criteria

    Diagnostic requirements:

    • • Obsessions/compulsions are time-consuming (>1 hour/day) or cause significant distress
    • • Not attributable to substance use or medical condition
    • • Not better explained by another mental disorder

Assessment Protocols

Validated tools for screening and severity tracking

  • Y-BOCS

    Yale-Brown Obsessive Compulsive Scale

    Criterion-standard severity measure. 10 items assessing obsessions and compulsions.

    Scoring:

    0-7: Subclinical | 8-15: Mild | 16-23: Moderate | 24-31: Severe | 32-40: Extreme

    Time:15-20 minutes

  • OCI-R

    Obsessive-Compulsive Inventory-Revised

    Brief 18-item self-report covering 6 OCD symptom dimensions.

    Scoring:

    Cut-off score: 21+ suggests clinically significant OCD symptoms

    Time:5-10 minutes

  • DOCS

    Dimensional Obsessive-Compulsive Scale

    Assesses 4 primary OCD dimensions: contamination, responsibility, symmetry, taboo thoughts.

    Scoring:

    Provides subscale scores for different OCD presentations

    Time:10-15 minutes

Causes & Etiology

  • Neurobiological

    • CSTC circuit dysfunction
    • Serotonin dysregulation
    • Elevated activity in orbitofrontal cortex and anterior cingulate
    • Reduced caudate nucleus volume in some studies

  • Genetic

    • Heritability: 45-65%
    • Polygenic inheritance
    • SLC1A1, DLGAP3, BTBD3 genes implicated
    • 10x increased risk with first-degree relative

  • Environmental

    • Childhood trauma
    • PANDAS/PANS
    • Stressful life events
    • Parental accommodation

  • Cognitive

    • Inflated sense of responsibility
    • Thought-action fusion
    • Intolerance of uncertainty
    • Overestimation of threat

Common Comorbidities

  • Major Depressive Disorder

    25-50%

    Either can come first; OCD precedes the mood disorder in about half of comorbid cases

  • Generalized Anxiety Disorder

    ~8%

    Overlapping worry patterns; rates higher in clinical samples

  • Social Anxiety Disorder

    ~44%

    Common co-occurring anxiety disorder; assess separately from OCD-related avoidance

  • Body Dysmorphic Disorder

    8-37%

    Both involve obsessive focus and compulsive checking

  • Tic Disorders

    20-30%

    Higher in childhood-onset OCD

  • ADHD

    10-25%

    Can complicate ERP due to attention deficits

Evidence-Based Treatments

  • ERP (Exposure and Response Prevention)

    First-line

    Gradual exposure to triggers while preventing compulsive responses.

    Evidence

    62% response (intent-to-treat) in a key RCT; outperformed clomipramine alone

    In practice

    First-line; typically 12-20 sessions

  • SSRIs

    First-line

    Higher doses than depression (e.g., fluoxetine 60-80mg)

    Evidence

    40-60% response rate

    In practice

    Takes 8-12 weeks for full effect; often combined with ERP

  • CBT with Cognitive Restructuring

    Adjunct

    Addresses dysfunctional beliefs about responsibility and threat

    Evidence

    May add to ERP; evidence for added benefit is mixed

    In practice

    Targets inflated responsibility, thought-action fusion

  • ACT (Acceptance and Commitment Therapy)

    Alternative

    Focuses on psychological flexibility rather than symptom reduction

    Evidence

    Emerging evidence; fewer trials than ERP

    In practice

    Teaches willingness to experience intrusive thoughts

  • Deep Brain Stimulation (DBS)

    Treatment-resistant

    Neurosurgical intervention for severe, refractory OCD

    Evidence

    About 53-57% response (35% or greater Y-BOCS drop) in refractory OCD

    In practice

    Reserved for cases failing multiple treatments

Try it with one client

Send a PHQ-9 or GAD-7 by secure link and read the scored result before the session.

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Obsessive-Compulsive Disorder questions

  • What is Obsessive-Compulsive Disorder?

    Obsessive-Compulsive Disorder (OCD) is a mental health condition defined in DSM-5-TR (ICD-10 code F42.2) by the presence of obsessions, compulsions, or both, that are time-consuming (more than 1 hour per day) or cause clinically significant distress or functional impairment. Obsessions are recurrent unwanted intrusive thoughts, urges, or images; compulsions are repetitive behaviors or mental acts the person performs in response to an obsession or according to rigid rules. OCD is no longer classified as an anxiety disorder in DSM-5-TR; it has its own chapter.

  • What are the symptoms of OCD?

    Common obsessions include contamination fears, fears of harm to self or others, intrusive sexual or violent thoughts, scrupulosity (religious or moral concerns), and need for symmetry or exactness. Common compulsions include excessive washing or cleaning, checking, counting, ordering or arranging, repeating actions, and seeking reassurance. Many people recognize the obsessions and compulsions as excessive, but insight varies (DSM-5-TR specifies good or fair, poor, or absent insight), and the urges are hard to resist. Avoidance of triggering situations is common.

  • How is OCD diagnosed?

    Diagnosis is made by a clinician using DSM-5-TR criteria, supported by structured assessment. The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) is the criterion-standard severity measure, used in nearly all OCD research. The Obsessive-Compulsive Inventory-Revised (OCI-R) is a validated 18-item self-report screener. A full clinical evaluation distinguishes OCD from related disorders (body dysmorphic disorder, hoarding disorder, trichotillomania), generalized anxiety disorder, and intrusive thoughts that are part of normal experience without clinical impairment.

  • What causes OCD?

    OCD is moderately heritable, with twin estimates higher in childhood-onset cases. Multiple genes contribute, and serotonin and glutamate systems are implicated. Neurobiologically, OCD reflects dysfunction in the cortico-striato-thalamo-cortical (CSTC) circuit, particularly involving the orbitofrontal cortex, anterior cingulate cortex, and basal ganglia. Environmental contributors include childhood adversity, perinatal complications, and in rare cases pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS). Cognitive factors include inflated responsibility beliefs and intolerance of uncertainty.

Scientific Sources

Evidence-Based

  • Y-BOCS Validation

    Goodman WK, Price LH, et al. The Yale-Brown Obsessive Compulsive Scale: I. Development, use, and reliability. Arch Gen Psychiatry. 1989;46(11):1006-1011.

  • DSM-5-TR Criteria

    American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR). 2022.

  • ERP Treatment Efficacy

    Olatunji BO, Davis ML, et al. Cognitive-behavioural therapy for obsessive-compulsive disorder: A meta-analysis of treatment outcome. Clin Psychol Rev. 2013;33(8):1206-1217.

  • Neurobiological Model

    Menzies L, Chamberlain SR, et al. Integrating evidence from neuroimaging and neuropsychological studies of obsessive-compulsive disorder. Neurosci Biobehav Rev. 2008;32(3):525-549.

  • SSRI Pharmacotherapy

    Soomro GM, Altman D, et al. Selective serotonin re-uptake inhibitors (SSRIs) versus placebo for obsessive compulsive disorder (OCD). Cochrane Database Syst Rev. 2008;(1):CD001765.

  • Comorbidity Patterns

    Ruscio AM, Stein DJ, et al. The epidemiology of obsessive-compulsive disorder in the National Comorbidity Survey Replication. Mol Psychiatry. 2010;15(1):53-63.