Department of Psychiatry

Penn Behavioral Health

Obsessive-Compulsive Disorder


Obsessive-compulsive disorder (OCD) is a psychiatric anxiety disorder most commonly characterized by a subject's obsessive, distressing, intrusive thoughts and related compulsions (tasks or "rituals") which attempt to neutralize the obsessions.

To be diagnosed with obsessive-compulsive disorder, one must have the presence of obsessions, compulsions, or both, according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5).

Obsessions are defined by:

  1. Recurrent and persistent thoughts, impulses, or images that are experienced at some time during the disturbance, as intrusive and unwanted, and that in most individuals cause marked anxiety or distress.
  2. The person attempts to ignore or suppress such thoughts, urges, or images, or to neutralize them with some other thought or action (for instance, by performing a compulsion).

Compulsions are defined by:

  1. Repetitive behaviors (e.g. hand washing, ordering, checking) or mental acts (e.g. praying, counting, repeating worlds silently) that the person feels driven to perform in response to an obsession, or according to rules that must be applied rigidly.
  2. The behaviors or mental acts are aimed at preventing or reducing distress, or preventing some dreaded event or situation; however, these behaviors or mental acts are not connected in a realistic way with what they are designed to neutralize or prevent, or are clearly excessive.

In addition to these criteria, the obsessions or compulsions must be time-consuming (taking up more than one hour per day), cause distress, or cause impairment in social, occupational, or school functioning. The symptoms are not attributable to any physiological effects of a substance or other medical condition. The disturbance is also not better explained by symptoms of another mental disorder.


The 1-year prevalence of OCD is estimated to be 1.2% in the US and 1.1%-1.8% internationally. Research indicates that females are affected at a slightly higher rate than males in adulthood, and males are more commonly affected than females in childhood.


OCD usually begins in adolescence or early adulthood, but it may also manifest in childhood. Typically, the onset of symptoms is gradual, although acute onset has also been reported. The majority of untreated individuals experience a chronic waxing and waning course, while others can experience episodic or deteriorating courses.

The phrase "obsessive-compulsive" has worked its way into the wider English lexicon, and is often used in an offhand manner to describe someone who is meticulous or absorbed in a cause (see "anal retentive"). It is important to distinguish these traits from OCD. Although these signs are often present in OCD, a person who shows signs of infatuation or fixation with a subject/object, or displays traits such as perfectionism, does not necessarily have OCD, a specific and well-defined condition.

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