What is the diagnostic approach for Obsessive-Compulsive Disorder (OCD)?

Diagnosing Obsessive-Compulsive Disorder

OCD diagnosis requires identifying recurrent, intrusive, distressing obsessions or compulsions that consume significant time (typically >1 hour/day) or cause marked distress and functional impairment, confirmed using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) with scores ≥28 indicating severe disease. 1

Core Diagnostic Features to Identify

The diagnosis hinges on recognizing three fundamental characteristics that distinguish OCD from other anxiety disorders:

• Abnormal risk assessment - patients overestimate danger in situations that pose minimal actual threat 2
• Pathologic doubt - persistent uncertainty despite repeated checking or reassurance 2
• Incompleteness - a pervasive sense that actions are not "just right" until performed in a specific way 2

These core features cut across all OCD subtypes and help differentiate true OCD from normal worries or other psychiatric conditions 2.

Clinical Interview Approach

Screen directly with specific questions about obsessions and compulsions, as patients rarely volunteer these symptoms spontaneously due to shame and fear of stigma 3, 4. The average delay in diagnosis is nearly 10 years, largely because clinicians fail to ask screening questions during routine mental status examinations 3, 2.

Key questions should probe for:

• Time-consuming repetitive thoughts that are intrusive, unwanted, and cause significant anxiety 1
• Repetitive behaviors or mental rituals performed in response to obsessions to reduce distress 5
• Functional impairment in work, school, or relationships due to these symptoms 5

Standardized Assessment Tools

• The Y-BOCS is the gold standard clinician-rated instrument for measuring OCD symptom severity 1
• Administer the Y-BOCS to quantify time spent on obsessions/compulsions, distress levels, and interference with daily functioning 6
• Scores ≥28 indicate severe OCD, while the clinical threshold typically requires symptoms taking >1 hour per day or causing significant distress/impairment 1, 6
• The Y-BOCS is content-independent, making it applicable across all OCD subtypes including relationship-themed, contamination, symmetry, and other variants 6

Essential Medical and Psychiatric Rule-Outs

Before confirming OCD, exclude medical conditions and assess comorbidities:

• Assess thyroid function, as hyperthyroidism can mimic or exacerbate OCD-like anxiety symptoms 1
• Screen for major depressive disorder, which has high comorbidity with OCD and significantly increases suicide risk 1
• Conduct comprehensive suicide risk assessment including current thoughts, plans, means, and intent, especially when depressive symptoms coexist 1
• Use the GAD-7 to distinguish generalized anxiety from OCD-specific anxiety patterns 1

Differential Diagnosis Considerations

Distinguish OCD from conditions with overlapping features:

• Schizotypal Personality Disorder - characterized by pervasive referential ideas and magical thinking across situations, not limited to OCD rituals 7
• Social Anxiety Disorder - fear of judgment in social situations may coexist with OCD but represents distinct pathology 7
• Obsessive-Compulsive Personality Disorder - lacks true obsessions and compulsions; instead shows rigid perfectionism and need for control 2
• Tourette's Syndrome - complex tics may resemble compulsions but have significant phenomenological overlap requiring careful distinction 2

Common Diagnostic Pitfalls

• Failing to use semi-structured interview tools and standardized symptom checklists leads to missed diagnoses 8
• Accepting comorbid depression as the primary diagnosis without screening for underlying OCD symptoms 1
• Mistaking normal relationship concerns for Relationship OCD - the Y-BOCS helps quantify the obsessional quality and functional impairment that distinguishes pathological symptoms 6
• Not assessing family accommodation, where relatives inadvertently reinforce symptoms through reassurance-giving or participation in rituals 6