What is obsessive compulsive disorder (OCD)?

Obsessive compulsive disorder (OCD) is defined as recurrent intrusive thoughts/images or repetitive behaviors due to urges or anxiety. It affects 1-3% of the US population, in both children and adults. The Diagnostic and Statistical Manual of Mental Disorders 5 (DSM-5) described the criteria as followed:


Recurrent and persistent thoughts, urges or images that are experienced, at some time during the disturbance, as intrusive, unwanted, and that in most individuals cause marked anxiety or distress. The individual attempts to ignore or suppress such thoughts, urges, or images, or to neutralize them with some thought or action.


Repetitive behaviors or mental acts that the person feels driven to perform in response to an obsession, or according to the rules that must be applied rigidly. 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 either are not connected in a realistic way with what they are designed to neutralize or prevent or are clearly excessive.

The common symptom dimensions in OCD can be categorized into:

  1. symmetry, arranging, ordering
  2. aggressive obsessions (harm to self or others)
  3. contamination, cleaning
  4. forbidden thoughts
  5. religious obsessions, morality, scrupulosity
  6. checking
  7. hoarding, collecting
  8. magical thinking
  9. tapping, sensory phenomenon
  10. health and somatic obsessions

A thorough list of OCD symptoms are described in the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), a common scale used to quantify the severity of OCD.