4.5 Obsessive-Compulsive Disorder (OCD)

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OBJECTIVE 1 — Diagnostic Criteria and Measures

What is OCD?

OCD stands for Obsessive-Compulsive Disorder. It is a mental health condition where a person experiences two main things:

• Obsessions — unwanted, repeated thoughts, images, or urges that pop into the mind and cause anxiety or distress. The person does not want these thoughts and cannot easily control them. For example, a person might keep having the thought "my hands are covered in germs and I will get seriously ill."

• Compulsions — repetitive behaviours or mental actions that the person feels forced to carry out in order to reduce the anxiety caused by the obsession. For example, washing their hands over and over again. The compulsion gives temporary relief, but the obsession always comes back, creating a vicious cycle.

Diagnostic Criteria for OCD

Doctors and psychologists use specific rules (called diagnostic criteria) to decide whether someone has OCD. These criteria come from classification systems such as the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, 5th Edition). The main criteria are:

1. Presence of obsessions, compulsions, or both.

   • Obsessions must be recurrent (they keep coming back), persistent (they are hard to stop), and experienced as intrusive and unwanted.
   • Compulsions are repetitive behaviours (e.g., handwashing, checking locks) or mental acts (e.g., counting, repeating phrases silently) that the person feels driven to perform in response to an obsession or according to rigid rules.

2. The obsessions or compulsions are time-consuming — they take up more than one hour per day on average.

3. They cause significant distress or interfere with the person's normal daily life — for example, affecting their work, school, or relationships.

4. The symptoms are not caused by a substance (e.g., a drug or medication) or by another medical condition.

5. The symptoms cannot be better explained by another mental disorder.