OCD: Differential diagnosis and screening questions

Here are the differential diagnoses and screening questions for OCD.

Differential diagnosis

• The main differential diagnosis is depression and many patients with OCD have comorbid depressive symptoms.
• Other differentials include phobic disorders, anorexia nervosa, obsessive or anakastic personality and occasionally schizophrenia.
• The symptoms of OCD are seen in other conditions such as Tourette's syndrome, autism and frontal lobe lesions.
• Obsessive-compulsive-related disorders (OCRD) and a range of disorders which share characteristics with OCD (e.g. in symptom profile, biology and treatment outcome).
• OCRDs include body dysmorphic disorder (BDD - concerns of imagined ugliness), hypochondriasis (concerns about imagined illness), eating disorders and impulse control disorders such as trichotillomania (hair pulling).

 Screening questions for OCD*

1. Do you have frequent unwanted thoughts that seem uncontrollable?
2. Do you try to get rid of these thoughts and, if so, what do you do?
3. Do you have rituals or repetitive behaviours that take a lot of time in a day?
4. Do you wash or clean a lot?
5. Do you keep checking things over and over again?
6. Are you concerned with symmetry and putting things in order?
7. Do your daily activities take a long time to complete?
8. Do these problems trouble you?
9. Does this behaviour make sense to you?

Non-psychiatrists who may be referred patients with OCD

Professional	Reason for consultation
GP	Anxiety, depression
Dermatologist	Chapped hands, eczema, trichotillomania
Cosmetic surgeon	Concerns about appearance
Oncologist	Fear of cancer
Genitourinary specialist	Fear of HIV
Neurologist	OCD associated with Tourette's syndrome
Obstetrician	OCD in pregnancy
Gynaecologist	Vaginal discomfort from douching

*These screening questions were compiled from the following articles:

• El-Sayegh S, Bea S and Agelopoulos A. "Obsessive Compulsive Disorder: Unearthing a hidden problem". Cleveland Clinic Journal of Medicine (2003) 70, Number 10: 824-840
• National Collaborating Centre for Mental Health commissioned by the National Institute for Health and Clinical Excellence. "Obsessive-compulsive disorder: Core interventions in the treatment of obsessive-compulsive disorder and body dysmorphic disorder". National Clinical Practice Guideline, Number 31. Published by The British Psychological Society and The Royal College of Psychiatrists, Jan 2006
• Heyman I, Mataix-Cols D, Fineburg N A. "Obsessive-compulsive disorder". BMJ (2006), 333: 424-429