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SJHH ... / Mental Health & Addiction Services/ Mental Health Services/ Anxiety Treatment and Research Clinic (ATRC)/ Definitions and Useful Links/ Obsessive-Compulsive Disorder (OCD)

Obsessive-Compulsive Disorder (OCD)

What is OCD?

OCD is a disorder that is associated with obsessions and compulsions, each of which is defined below.


Obsessions are the mental component of OCD. They are thoughts, images, or impulses that repeatedly enter the mind, and feel out of the individual’s control. The person with OCD does not want to have these ideas, finds them intrusive, and usually at some point has recognized that they don't truly make sense. This is an important feature of obsessions, as it helps to distinguish them from other non-OCD symptoms such as worry or depressive preoccupations, and from other human experiences like fantasy. Obsessions are accompanied by troubling feelings that can take many forms, such as fear or apprehension, anxiety, disgust, tension, or a sensation that things are “not just right.”

Recent research shows that the symptoms of OCD follow a few broad themes; within these themes, obsessions can take a countless number of forms. Common examples include the following:

  • Contamination (e.g., fears of germs, dirtiness, chemicals, AIDS, cancer)
  • Symmetry or exactness (e.g., of belongings, spoken or written words, the way one moves or completes actions)
  • Doubting (e.g., whether appliances are turned off, doors are locked, written work is accurate, etc.)
  • Aggressive Impulses (e.g., thoughts of stabbing one’s children, pushing loved ones into traffic, etc.)
  • Accidental Harm to Others (e.g., fears of contaminating or poisoning a loved one, or of being responsible for a break in or a fire)
  • Religion (e.g., sexual thoughts about a holy person, satanic thoughts, distressing thoughts regarding morality)
  • Sexual (e.g., thoughts about personally upsetting sexual acts)
  • Other miscellaneous obsessions having to do with themes such as lucky or unlucky colors or numbers, or with the need to know “trivial” details (e.g., house numbers, license plates)


The distressing feelings that arise from obsessions motivate people with OCD to engage in specific behaviors or rituals that may temporarily provide relief from their distress. These are compulsions, the main behavioural component of OCD. Compulsions are acts the person feels driven to perform over and over again, or sometimes according to specific personal "rules." OCD compulsions do not give the person pleasure; they are performed to obtain relief from discomfort caused by the obsessions. This is an important feature of compulsions because it helps to distinguish them from other non-OCD problems like gambling or addictions, other impulsive behaviors (e.g., spending too much money, stealing), or normal behaviors such as avid hobbies or pastimes. Even though compulsions are usually recognized as excessive, embarrassing, or problematic, people with OCD feel powerless to resist them.

Like obsessions, compulsions can take many forms, which can include the following:

  • Washing and Cleaning (e.g., excessive showering, hand washing, house cleaning)
  • Checking (e.g., locks, appliances, paperwork, driving routes)
  • Counting (e.g., preferences for even or odd numbers, tabulating figures)
  • Repeating Actions or Thoughts (e.g., turning lights on and off, getting up and down in chairs, re-reading, re-writing)
  • Need to Ask or Confess (e.g., asking for reassurance)
  • Hoarding (e.g., magazines, flyers, clothing, information)
  • Ordering and Arranging (e.g., need for things to be straight, sequenced, or in a certain order)
  • Repeating Words, Phrases, or Prayers to Oneself (e.g., repeating "safe" words or prayers)

Compulsions can take up considerable time, and often cause problems in day-to-day life in many ways. For example, people with contamination obsessions may wash so often and so long that their hands become inflamed. A person with doubting obsessions about whether she has performed routine activities may be chronically late for appointments, due to repeated checking of appliances or taps.

Other Behavioural Features of Obsessive-Compulsive Disorder

Although obsessions and compulsions are the key symptoms of OCD, other common features include the following:

  • Avoidance – Compulsions are performed in the attempt to reduce negative emotions, such as anxiety, that arise from obsessions. Another behavior that can also perform this function is avoidance. People with OCD often find that they avoid situations that provoke obsessions. Avoidance can take many forms – some of them quite subtle – and can have a profound impact on the individual’s day-to-day life. For example, a person with intrusive thoughts about harming his child may feel a need to avoid being alone with the child, bathing or dressing the child, or even looking at pictures of the child, all because these situations have the power to evoke distressing obsessions.
  • Thought Suppression – Some obsessions, particularly those that are personally offensive or frightening, can prompt the person to spend a lot of energy deliberately trying to force obsessive thoughts out of awareness, or to suppress them. Although thought suppression is an understandable strategy, research has shown it to be problematic in OCD in several ways: a) deliberately trying not to think of a specific thing usually has the contrary effect of making the thought more likely to return, and b) unintentionally, it reinforces the notion that the obsession is a valid belief or fear, when in fact it is not; this can serve to strengthen the distress power of the obsession. Either way, the effect of thought suppression may be to increase obsessions.

Official Diagnostic Criteria for OCD

Based on criteria from the Fifth Edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5; American Psychiatric Association, 2013)

  • The presence of obsessions or compulsions (as described above).
  • The individual’s obsessions or compulsions cause significant distress (i.e., it bothers the person that he or she has the problems) or significant interference in the person’s day-to-day life. For example, the obsessions or compulsions may make it difficult for the person to perform important tasks at work, interfere with relationships, or get in the way of other day-to-day tasks.
  • If another psychological problem is present, the obsessions and compulsions are not restricted to it. For example, people with bulimia often ruminate about food and engage in repetitive behaviors, such as binge eating and purging. This would not be considered OCD.
  • The obsessions and compulsions are not simply due to a substance or medical condition.

Causes of OCD

Biological Factors

  • Brain Activity – There is much current interest in identifying brain areas involved in OCD, using imaging techniques like positron emission tomography (PET) and magnetic resonance imagery (MRI). To date, research has identified a number of brain areas where people with OCD appear to have different amounts of activity compared to those without OCD. These include complex brain circuits involving the front part of the brain (the orbital cortex) and parts of deeper structures (the basal ganglia), which are thought to be involved in controlling feelings and actions. The precise nature of these differences is not completely understood, and studies often have inconsistent results.
  • Neurotransmitters – Neurotransmitters are chemical messengers that pass information from one nerve cell in the brain to the next. The neurotransmitter most clearly implicated in the development and maintenance of OCD is serotonin. The greatest evidence for this comes from the finding that medications that act to increase levels of serotonin at several sites in the brain – such as serotonin reuptake inhibitors – are effective in reducing obsessions and compulsions.
  • Genetics – Evidence is quite strong that OCD runs in families. No specific genes for OCD have yet been identified, so vulnerability to OCD cannot be determined via genetic testing. However, research suggests that genes can play a role in the development of the disorder. Recent research suggests that when a parent has OCD, the risk that a child will develop OCD is increased slightly, but this may only be true for some forms of OCD. For example, factors implicated in familial include age of onset (e.g., childhood-onset OCD tends to run in families) and family history of tic-related disorders, like Tourette’s disorder.

Psychological Factors

  • Beliefs about Obsessions – People’s interpretations of events are often a major cause of their emotional responses to them. In the case of OCD, misinterpretations often focus on the meaningfulness of obsessive thoughts. Research has shown that almost everyone has intrusive thoughts once in a while – almost like mental “hiccups” -- and also that the themes of these normal intrusive thoughts are identical to those found in obsessions (e.g., being responsible for something bad happening, doubts about whether a task was done properly). The difference may be that in OCD these thoughts are interpreted differently, giving them the power to cause much greater distress. Problematic beliefs about obsessions can take many forms. Examples include the belief that having a thought is the same as doing an action (e.g., if I think about pushing a loved one into traffic it is as bad as actually doing it) or the belief that having a thought means that I would be responsible for any harmful consequences if I did not take all possible actions against it.
  • Personality Traits – Research has shown that several general personality traits may be linked to some forms of OCD. One of these is trait anxiety, or the predisposition to be made anxious more easily, or more frequently, or by a greater number of experiences, than other people. Another is anxiety sensitivity, or the tendency to feel uncomfortable with, and have catastrophic thoughts about, one’s anxiety (e.g., a racing heart may prompt thoughts that one might lose control or go crazy). Another trait sometimes associated with OCD is perfectionism, particularly when it entails excessively high or rigid standards for oneself that rarely, if ever, feel satisfied.
  • Attention & Information Use – People with OCD tend to pay special attention to information that is in line with their concerns, and less attention to information that isn’t. For example, someone with contamination concerns related to contracting AIDS may focus in on a statement he once heard about the remote possibility that mosquitoes can transmit the disease. The anxiety prompted by this information has several problematic consequences: a) the desperate search to check this threatening fact with 100% certainty – rarely possible in the real world – results in other information that is neutral or contradictory being downplayed, and b) anxiety reducing compulsive behaviors like reassurance-seeking, prompted by this information, may be reinforced because they feel like rational information seeking.
  • Life Experiences – Life stress puts people with OCD at risk for worsening of their symptoms. During stressful periods (e.g., a new baby, work stress, marital problems, exams at school), people with OCD often report increased obsessions and greater difficulty resisting compulsions. Other emotional problems, such as depression, may also interact with OCD vulnerability to worsen its symptoms.

Effective Treatments for OCD

Biological Treatments

Drugs traditionally used to treat anxiety have not been found to be very effective at reducing obsessions and compulsions. However, a number of medications originally developed as antidepressants have been shown to be useful for treating OCD. All of these medications affect the brain neurotransmitter serotonin. Examples of these medications include:

Type of Medication Generic Name Brand Name
Tricyclic Antidepressants Clomipramine Anafranil
SSRI Antidepressants Citalopram

The decision of whether to take medication for OCD, and which medication to take should be based on the individual’s past treatment history, the individual’s medical history, possible interactions between the medication and other drugs that person may be taking, potential side effects, and other factors.

In rare cases, individuals with OCD may benefit from combining more than one medication. For example, some people (particularly those who do not respond to an SSRI alone, or those have difficulty recognizing that their obsessions and compulsions are excessive or unreasonable), may benefit from the combination of an SSRI antidepressant and a medication such as risperidone (a medication that is also used to treat psychotic symptoms such as hallucinations and delusions).

In very rare cases, individuals with OCD may undergo cingulotomy, a type of brain surgery. This intervention is reserved for the most severe forms of OCD, after all other treatment options have failed. A significant percentage of individuals who undergo this procedure experience a reduction in OCD symptoms, despite not having responded to the usual treatments previously.

Psychological Treatments

Research has shown two types of psychological treatment to be effective for treating OCD: behavior therapy and cognitive therapy. Because techniques from these two treatments are often used jointly, this general type of treatment is often known as cognitive behavioural therapy (CBT). To date, the most evidence exists for the effectiveness of the behavioural component of CBT.

CBT is based upon the following understanding of OCD: Obsessions, with their power to elicit such distress, lead the individual to engage in behaviors (e.g., compulsions, avoidance), which may provide a temporary relief. However, these compulsive behaviors are problematic for several reasons:

  1. They cause the person to become very sensitized to their obsessions. That is, the “quick fix” of the compulsion takes away the opportunity to “ride out” the anxiety and logically evaluate both the reasonableness of the thought as well as one’s true ability to bear the anxiety. This strengthens the power of the obsession to cause distress.
  2. Because they may at times provide partial temporary relief, compulsions are self-perpetuating: even partial anxiety reduction on one or two occasions will prompt the person to respond quickly with a similar behavior the next time anxiety arises.
  3. Compulsive behaviors themselves quickly begin to cause problems in day-to-day life (e.g., taking priority over other more important activities).

So, CBT has two general aims: a) controlling compulsive rituals and avoidance, and b) reducing the anxiety associated with obsessions, and through this, reducing their intensity and frequency.

  • Behavior Therapy - The building blocks of behavior therapy for OCD are exposure and ritual prevention (ERP). ERP involves a) confronting a distressing situation or experience repeatedly, until it no longer triggers distress, while b) resisting the drive to engage in problematic anxiety-reducing behaviors. In the case of OCD, it is the obsessions that prompt the distress. So, in ERP for OCD, exposure is to obsessions, accomplished through deliberately seeking out situations that have the power to provoke them. For example, an individual with contamination obsessions about germs could be encouraged to practice touching items that have been in public places, with no compulsive washing or avoidance -- something that would quickly prompt their obsessive thoughts -- until this no longer causes notable anxiety. A new situation could then be added, and practiced until it also loses its power to cause anxiety, and so on. Over time, exposure first weakens the distress caused by obsessions, then the frequency and intensity of the obsessions themselves. ERP works best when it occurs frequently (e.g., at least four or five times per week), and lasts long enough for the anxiety to decrease (up to two hours).
  • Cognitive Therapy – Involves learning to identify one’s anxious beliefs about the meaning of obsessions and to replace them with more realistic thoughts. For example, if an individual is concerned that having an obsession about harming someone may make it more likely that that will actually happen, the individual might be taught to examine the evidence for the specific belief (e.g., I’ve had that thought hundreds of times and it has never happened) or for the more general belief that all thoughts that pop into one’s mind are always meaningful.

Combined Treatments

Generally, medications and CBT work about equally well in the short term, although some people may respond better to one approach or the other. In addition, some individuals appear to respond best to the combination of CBT and medications, whereas others do just as well with only one of these treatments. In the long term, CBT or combined approaches may be more useful that medication treatment alone. Once treatment has stopped, individuals who have been treated with a full course of CBT are less likely to experience a rapid return of symptoms than are individuals who have been treated with medication alone. In addition, should symptoms increase in another OCD theme area (e.g., doubts about harming someone, concerns about contracting a disease), the techniques learned in CBT can be applied to the new area of difficulty.

Did you know ...?

  • OCD affects about one percent of the population, although estimates are somewhat inconsistent across studies.
  • In adults, OCD is slightly more common in women than in men, but in children the pattern is reversed. More boys than girls have OCD, and OCD often has an earlier onset in boys than in girls.
  • About 90% of people have occasional intrusive thoughts and repetitive behaviors that are very similar to those that occur in OCD. The main difference is that people with OCD experience obsessions and engage in compulsions much more frequently than the average person, and are much more distressed by their symptoms.

Suggested Readings

Readings for Consumers

  1. Antony, M.M., & Swinson, R.P. (1998). When perfect isn't good enough. Oakland, CA: New Harbinger Publications.
  2. Baer, L. (2000). Getting control: Overcoming your obsessions and compulsions, Revised Edition. New York, NY: Plume.
  3. Baer, L. (2001). The imp of the mind. New York: Dutton.
  4. Chansky, T. (2000). Freeing your child from obsessive-compulsive disorder. New York: Crown.
  5. Ciarrochi, J. W. (1995). The doubting disease. Mahwah, New Jersey: Paulist Press.
  6. de Silva, P. & Rachman, S. (1998). Obsessive-compulsive disorder: The facts (2nd ed.). New York, NY: Oxford University Press.
  7. Foa, E.B., & Kozak, M.J. (1997). Mastery of your obsessive compulsive disorder, client workbook. Boulder, CO: Graywind Publications.
  8. Foa, E.B. & Wilson, R. (2001). Stop obsessing! How to overcome your obsessions and compulsions, revised edition. New York: Bantam Books.
  9. Hyman, B., & Pedrick, C. (1999) The OCD workbook. Oakland, CA: New Harbinger Publications, Inc.
  10. Osborn, I. (1998). Tormenting thoughts and secret rituals: The hidden epidemic of OCD. New York: Pantheon Books.
  11. Penzel, F. (2000). Obsessive-compulsive disorders: A complete guide to getting well and staying well. New York: Oxford University Press.
  12. Rapoport, J. (1999). The boy who couldn't stop washing, Penguin Books, New York.
  13. Schwartz, J.M. (1996). Brain lock: Free yourself from obsessive-compulsive behavior. New York: HarperCollins.
  14. Steketee, G.S. (1999). Overcoming obsessive compulsive disorder (client manual). Oakland, CA: New Harbinger Publications.
  15. Steketee, G., & White, K. (1990). When once is not enough. Oakland, CA: New Harbinger Publications.

Readings For Professionals

  1. Foa, E.B., & Franklin, M.E. (2001). Obsessive compulsive disorder. In D.H. Barlow (Ed.), Clinical handbook of psychological disorders, third edition. New York: Guilford Press.
  2. Frost, R.O., & Steketee, G. (Eds.) (2002). Cognitive approaches to obsessions and compulsions: Theory, assessment, and Treatment; Oxford, UK: Pergamon.
  3. Goodman, W.K., Rudorfer, M.V., & Maser, J.D. (1999). Obsessive-compulsive disorder: Contemporary issues in treatment. Mahwah, NJ: Lawrence Erlbaum Associates, Inc.
  4. Jenike, M.A., Baer, L., & Minichiello, W.E. (1998). Obsessive-compulsive disorders: Practical management. St. Louis, MO: Mosby.
  5. Koran, L.M. (1999). Obsessive-compulsive and related disorders in adults: A comprehensive clinical guide. New York: Cambridge University Press.
  6. Kozak, M.J., & Foa, E.B. (1997). Mastery of your obsessive compulsive disorder, Therapist guide. Boulder, CO: Graywind Publications.
  7. March, J., & Muller, K. (1998). OCD in children and adolescents: A cognitive-behavioral treatment manual, New York: Guilford Press.
  8. Steketee, G.S. (1993). Treatment of obsessive-compulsive disorder, New York: Guilford Press.
  9. Steketee, G. S, (1998). Overcoming OCD: A behavioral and cognitive protocol for the treatment of OCD. New York, NY: New Harbinger.
  10. Steketee, G., & Pigott, T. (1999). Obsessive compulsive disorder: The latest assessment and treatment strategies. Evanston, WY: Compact clinicals.
  11. Swinson, R.P., Antony, M.M., Rachman, S., & Richter, M.A, (Eds.) (1998). Obsessive-compulsive disorder: Theory, research and treatment. New York: Guilford Press.

Video Resources

  1. Obsessive Compulsive Foundation (1993). The touching tree: A story of a child With OCD (video tape). North Branford, CT: Obsessive-Compulsive Foundation.
  2. Obsessive Compulsive Foundation, & Grayson, J. (1997). G.O.A.L. (Giving Obsessive-compulsives another lifestyle (video tape). North Branford, CT: Obsessive-Compulsive Foundation.
  3. Turner, S.M. (1996). Behavior therapy for obsessive-compulsive disorder (video tape). APA Psychotherapy Videotape Series. Washington, DC: American Psychological Association.

© 2002 Laura J. Summerfeldt, Ph.D. & Martin M. Antony, Ph.D.