What is obsessive-compulsive disorder?

Obsessive-compulsive disorder (OCD) is a mental health condition characterised by persistent, unwanted thoughts and repetitive behaviours that significantly interfere with daily life.

Diagnostic criteria for OCD

The diagnostic criteria for OCD are outlined in the International Classification of Diseases (ICD-11), which provides a standardised framework for identifying the disorder.

Key requirements for diagnosis

• Symptoms must be time-consuming (taking more than one hour per day) or cause significant distress or dysfunction.
• Insight varies – individuals may have poor or absent insight or fair to good insight.

Symptoms of OCD: obsessions and compulsions

OCD symptoms fall into two main categories: obsessions and compulsions.

Obsessions

Obsessions are repetitive, persistent thoughts, images, or impulses that are unwanted and intrusive.

Compulsions

Compulsions are repetitive behaviours or mental acts performed in response to obsessions, often to neutralise or reduce the associated anxiety. These can be physical actions, such as tapping, or mental ones, like sub-vocal counting.

Research into OCD: Rapoport (1989) case study

One notable study is Rapoport's (1989) investigation, which examined OCD in a teenage patient and tested the effectiveness of drug therapy.

Aim

The study aimed to investigate OCD in a teenage patient, including the efficacy of drug treatments.

Method

• This was a case study focusing on Charles, who had an obsession with stickiness, leading to compulsive washing that took many hours each day.
• The researcher conducted an electroencephalogram (EEG).
• Charles was prescribed clomipramine (a tricyclic antidepressant).

Results

• After the EEG, Charles spent all night washing due to the stickiness of the electrodes.
• Four weeks after starting clomipramine, he was able to pour and touch honey.
• He relapsed within 12 months due to tolerance, though symptoms later reduced.

Conclusions

Clomipramine is effective in the short term, but maintenance doses are required to prevent relapse.

Evaluation of Rapoport (1989)

• Strength: Qualitative data – Open-ended questions provided detailed insights into Charles' beliefs, such as responses to "What would happen if your washing routine was disrupted?".
• Weakness: Generalisation – As a single case of a 14-year-old boy, findings may not apply to other age groups; for example, children often exhibit counting, checking, and repetitive movements, while adults tend to ruminate.

Measures for assessing OCD

Accurate measurement is essential for diagnosing and monitoring OCD. Two key tools are the Maudsley Obsessive-Compulsive Inventory (MOCI) and the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS).

The Maudsley Obsessive-Compulsive Inventory (MOCI)

The MOCI is a questionnaire with 30 true-or-false statements, developed from interviews with 30 people with OCD. It categorises respondents into four types: cleaning, checking, slowness, and doubting. A sample item is: "I avoid using public telephones because of possible contamination."

The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS)

The Y-BOCS is a semi-structured interview with ten items that measure symptom severity on a five-point scale (0–4, from none to extreme). It takes about 30 minutes and includes an accompanying checklist to diagnose OCD type.

Evaluating the diagnosis and measurement of OCD

Evaluating diagnostic tools and measures is crucial to ensure they are reliable (consistent) and valid (accurate). The following table summarises strengths and weaknesses for the MOCI, Y-BOCS, and broader diagnostic approaches.