A 32-year-old man with OCD presents with recurrent checking behaviors (checking locks, appliances, door handles 20+ times daily). Which is the most common obsessive-compulsive subtype associated with checking compulsions?

Explanation

## Harm/Responsibility Obsessions and Checking Compulsions **Key Point:** Fear of harm (to self or others) or responsibility for preventing harm is the most common obsessive theme associated with checking compulsions, occurring in 25–35% of OCD patients. ### OCD Subtypes and Associated Compulsions | Obsessive Theme | Associated Compulsion | Prevalence | Key Features | |---|---|---|---| | **Harm/Responsibility** | **Checking, reassurance-seeking** | **25–35%** | **Fear of causing harm; repeated verification** | | Contamination | Washing, cleaning, avoidance | 40–50% | Fear of germs or pollutants | | Symmetry/Exactness | Arranging, ordering, repeating | 20–30% | Need for things to be "just right" | | Sexual/Aggressive Thoughts | Mental rituals, avoidance | 10–15% | Ego-dystonic intrusive thoughts | ### Clinical Presentation of Harm/Checking OCD **High-Yield:** Harm obsessions typically manifest as: - Intrusive thoughts about causing harm (e.g., "Did I hit someone with my car?") - Excessive responsibility for preventing catastrophe - Compulsive checking (locks, appliances, switches, mirrors) - Reassurance-seeking from family members - Avoidance of situations where harm might occur - Significant functional impairment due to time spent checking **Clinical Pearl:** Checking compulsions are often paradoxically reinforced—each check provides temporary relief but increases doubt, leading to more checking. This creates a vicious cycle of escalating checking behavior. ### Mechanism of Checking Compulsions ```mermaid flowchart TD A[Intrusive thought: 'Did I lock the door?']:::outcome A --> B[Anxiety/doubt increases]:::outcome B --> C{Perform checking ritual?}:::decision C -->|Yes| D[Temporary anxiety relief]:::action C -->|No| E[Anxiety persists/escalates]:::urgent D --> F[Doubt returns; cycle repeats]:::outcome F --> G[Checking behavior strengthens]:::urgent E --> H[Avoidance develops]:::action ``` **Warning:** Do not confuse harm OCD with actual violent ideation or psychotic delusions. In OCD, patients recognize the thoughts as irrational and are distressed by them (ego-dystonic); in psychosis, beliefs are held with conviction. **Mnemonic:** **HARM** = **H**arm obsessions, **A**voidance, **R**eassurance-seeking, **M**ultiple checks [cite:DSM-5 Diagnostic Criteria for OCD; Abramowitz et al. (2006) Obsessive-Compulsive Disorder: Subtypes and Spectrum]