Obsessive-Compulsive Disorder (OCD)
As is the case for many psychiatric disorders, there is no laboratory test for OCD. There are, however, specific clinical interview and assessment tools designed to aid in diagnosis. Even with the correct clinical diagnostic tools, it can be difficult to distinguish OCD from other psychiatric conditions (Seibell 2013; Sudak 2012).
The difficulty in correctly diagnosing OCD may stem in part from the frequency with which OCD is associated with other psychiatric disorders (Seibell 2013; Sudak 2012). In one study, 92% of patients with a primary diagnosis of OCD had at least one additional psychiatric diagnosis (de Mathis 2013). Nevertheless, in order to make an OCD diagnosis, a clinician must rule out other psychiatric conditions such as depression, anxiety disorder, psychosis, and ADHD (Masi 2006; Yip 2014; Sudak 2012).
Once an OCD diagnosis has been made, severity can be graded using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), Clinical Global Impressions (CGI) scale, or both:
- The Y-BOCS is a clinician-administered 10-item questionnaire that rates the frequency, severity, and types of symptoms in an OCD patient, and can be used to monitor disease progression or treatment. Y-BOCS scores range from 0 to 40, with 40 being the most severe (Rosario-Campos 2006; Goodman 1989; Farris 2013).
- The CGI scale can be used to assess the clinical severity of any mental disorder. It scores symptoms on two 7-point scales: severity of symptoms and response to treatment. The CGI usually rates the patient’s symptoms, behavior, and function over the previous seven days (Busner 2007; Seibell 2013).
Diagnostic Criteria for OCD
Both the World Health Organization (International Statistical Classification of Diseases and Related Health Problems; ICD-10) and the American Psychiatric Association (Diagnostic and Statistical Manual of Mental Disorders; DSM-5) have developed diagnostic criteria for OCD.
ICD-10 criteria (National Collaborating Centre for Mental Health 2006):
Obsessional symptoms or compulsive acts or both must be present on most days for at least two successive weeks and be a source of distress or interference with activities. Obsessional symptoms should have the following characteristics:
DSM-V criteria (APA 2013):
A. Presence of obsessions, compulsions, or both:
Obsessions are defined by (1) and (2):
Compulsions are defined by (1) and (2):
B. The obsessions or compulsions are time-consuming, taking more than one hour per day, or cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.
C. The obsessive-compulsive symptoms are not attributable to the physiological effects of a substance (eg, a drug of abuse or a medication) or another medical condition.
D. The disturbance is not better explained by the symptoms of another mental disorder.