Obsessive-Compulsive Disorder (OCD): Symptoms and Treatment


What is OCD?

Obsessive-compulsive disorder (OCD) is characterized by repetitive, intrusive, anxiety-provoking thoughts (obsessions), and behaviors to relieve that anxiety (compulsions). Patients attempt to neutralize obsessions with compulsions, but these behaviors or mental acts cannot prevent realistically speaking, or are clearly excessive. Most patients with OCD have good insight that their OCD beliefs are not true, but some patients have poor insight, and a small percentage have absent insight—their thoughts are delusional. Some may have only obsessions or only compulsions, but in most cases both obsessions and compulsions are present. Healthy individuals, too, experience occasional intrusive thoughts, some of which are concerned with themes similar to those of obsessional patients. It is the frequency, intensity, and, above all, the persistence of obsessional phenomena that characterizes OCD.

The rituals of OCD are called compulsions only when the rituals become excessive and interfere with normal function. Unwanted thoughts about dirt, germs, or contamination lead to compulsive washing and bathing. Repetitive thoughts about whether a task was properly performed (locking the door, shutting off the stove) can lead to compulsive checking. Persistent doubting and uncertainty about whether something will be needed in the future leads to compulsive hoarding.

Person washing his hands (done repeatedly in OCD)
Person washing his hands (done repeatedly in OCD) (Pic Credit: By Lars Klintwall Malmqvist (Larsklintwallmalmqvist) – Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=4112060)

OCD can be disabling, making it difficult to learn, hold a job, or perform normal household tasks. It can arise in childhood to young adulthood, with either an intermittent or chronic course. Lifetime prevalence appears to be 2.3%. OCD has a median age of onset of 19. Approximately 25% of cases have onset by age 10. Early onset is more common in males. Onset after 30 is rare. OCD has similar features in children and in adults, but compulsions are more central earlier in life, with some children either not experiencing obsessions or being unable to articulate them. OCD is highly comorbid with depression, tic disorders, and other anxiety disorders.

Certain behaviors are sometimes described as ‘‘compulsive,” including sexual behavior (in the case of paraphilias), gambling (i.e., gambling disorder), and substance use (e.g., alcohol use disorder). However, these behaviors differ from the compulsions of OCD in that the person usually derives pleasure from the activity and may wish to resist it only because of its harmful consequences. Obsessions and compulsions with sexual content can occur in OCD. Sexual obsessions were reported in 32 percent of the OCD patients in a large study. However, the content of these obsessions consisted most often not of sexual fantasies but of fears of acting on sexual impulses or fears of being a pervert.

Symptoms of OCD

OCD is characterized by obsessional thinking, compulsive behavior, and varying degrees of anxiety, depression, and depersonalization.

Obsessional thoughts are words, ideas, and beliefs that are recognized by patients as their own, and that intrude forcibly into the mind. They are usually unpleasant, and attempts are made to exclude them. It is the combination of an inner sense of compulsion and of efforts at resistance that characterizes obsessional symptoms.

Obsessional thoughts may take the form of single words, phrases, or rhymes, are usually unpleasant or shocking to the person, and may be obscene or blasphemous. Obsessional images are vividly imagined scenes, often of a violent or disgusting kind (e.g. involving sexual practices that the person finds abhorrent). Obsessional ruminations are internal debates in which arguments for and against even the simplest everyday actions are reviewed endlessly. Some obsessional doubts concern actions that may not have been completed adequately (e.g. turning off a gas tap or securing a door), while other doubts concern actions that might have harmed other people (e.g. that driving a car past a cyclist might have caused him to fall off his bicycle). Sometimes doubts are related to religious convictions or observances.

Obsessional impulses are urges to perform acts, usually of a violent or embarrassing kind (e.g. leaping in front of a car, injuring a child, or shouting blasphemies at a religious ceremony). Obsessional rituals include both mental activities (e.g. counting repeatedly in a special way, or repeating a certain form of words) and repeated but senseless behaviors (e.g. washing the hands 20 or more times a day). Some rituals have an understandable connection with the obsessional thoughts that precede them (e.g. repeated hand washing following thoughts about contamination). Other rituals have no such connection (e.g. arranging objects in a particular way). The person may feel compelled to repeat such actions a certain number of times, and if this sequence is interrupted it has to be repeated from the beginning. People who use rituals are usually aware that these are illogical, and usually try to hide them. Some people are afraid that their symptoms are a sign of impending madness, and need to be reassured that this is not so.

Obsessional slowness. Although obsessional thoughts and rituals lead to slow performance, a few obsessional patients are afflicted by extreme slowness that is out of proportion to other symptoms.

Obsessional phobias. Obsessional thoughts and compulsive rituals may worsen in certain situations—for example, obsessional thoughts about harming other people may increase in a kitchen or other place where knives are kept. The person may avoid such situations because they cause distress, just as people with phobic disorders avoid specific situations.

Anxiety. This is a prominent component of OCDs. While some rituals decrease anxiety, others increase anxiety.

Depression. Obsessional patients are often depressed. Although depression is an understandable reaction to the obsessional symptoms, the depression can also be independent of them.

Depersonalization. Some obsessional patients complain of depersonalization. The relationship between this and the other symptoms of the disorder is unclear.

Contamination. Contamination obsessions are the most frequently encountered obsessions in OCD. Such obsessions are usually characterized by a fear of dirt or germs, but they could also involve toxins or environmental hazards (e.g., asbestos or lead) or bodily waste or secretions. Patients usually describe a feared consequence of contacting a contaminated object, such as spreading a disease or contracting an illness themselves. Occasionally, however, the fear is based on the sensory experience of not being clean. This can change over time; for example, a fear of cancer may be replaced by a fear of contracting a sexually transmitted disease.

Many patients with contamination fears use avoidance behavior and try to avoid the contaminant. Excessive washing is the compulsion most commonly associated with contamination obsessions. It usually occurs after contact with the feared object, but, even mere proximity to the feared object is often enough to cause severe anxiety and washing compulsions.

Need for Symmetry. This is a drive to order or arrange things perfectly or to perform certain behaviors symmetrically or in a balanced way, until they achieve a “just right” feeling that the act has been completed perfectly. They may have little anxiety and may describe feeling unsettled or uneasy if they cannot repeat actions or order things to their satisfaction. In addition to a need for perfection, the drive to achieve balance or symmetry may be connected with magical thinking. For example, a college student felt compelled to walk across doorway thresholds exactly in the center to prevent something terrible from happening to his parents.

The desire to “even up” or balance movements may be present in patients with tapping or touching rituals. For instance, they may feel that the right side of the chair must be tapped after the left side has been tapped. Patients with a need for symmetry frequently present with obsessional slowness, taking hours to perform acts such as grooming or brushing their teeth.

Sexual and Aggressive Obsessions. People with sexual or aggressive obsessions are plagued by fears that they might harm others or commit a sexually unacceptable act such as molestation. Often, they are fearful also that they have already committed the act. Patients are usually horrified by their obsessional thoughts and do not like to reveal them. They frequently have checking and confession or reassurance rituals. They may report themselves to the police or repeatedly seek out priests to confess their imagined crimes.

Pathological Doubt. Pathological doubt, also referred to as over-responsibility for harm, is a common feature of OCD. They are plagued by the concern that, as a result of their carelessness, they will be responsible for a dire event. They may worry, for example, that they will start a fire because they neglected to turn off the stove before leaving the house. Although many patients report being fairly certain that they performed the act in question (e.g., locking the door, unplugging the hairdryer, paying the correct amount on a bill), they cannot dismiss the nagging doubt, the “What if?” This can lead to marked avoidance behavior. They may be plagued by the doubt that they inadvertently harmed someone without knowing that they did so.

Mental Compulsions/Rituals. Mental compulsions are thoughts that aim to prevent or decrease anxiety caused by obsessions. Mental rituals are the third most common type of compulsion after hand washing and checking. Over-responsibility for harm (e.g., fear of harming self/other, being responsible for something bad happening) is the most frequently encountered obsession among mental compulsions/rituals, followed by fears of offending God and sacrilegious thoughts, then unwanted sexual thoughts, violent thoughts/mental imagery, concern with illness and disease, and lucky and unlucky numbers. With regard to compulsions, praying is the most frequently endorsed type of mental ritual, followed by undoing bad thoughts with good thoughts, and then repeating phrases and mantras, mental checking, counting, and mental “word games.”

It is important to distinguish mental rituals from obsessions because behavior therapy uses different techniques for these symptoms: exposure is used for obsessions, and response prevention for compulsions.

Insight. Patients with OCD may have varying degrees of insight (an awareness of the senselessness of obsessions), with absent insight / delusional OCD beliefs at one extreme with complete insight at the other. The degree of insight can vary both within a single episode and across different episodes.

Some, but not all, studies have found that poorer insight in OCD is associated with poorer response to medication and behavior therapy. However, more studies are needed. It is also unclear why some episodes are accompanied by better insight than others.

Causes of OCD

Genetics. The risk of OCD in first-degree relatives is increased almost fourfold compared with control rates. Molecular genetic studies have found a number of associations between OCD and various genes.

Brain disorder. Two kinds of evidence suggest a disorder of brain function in OCD—first, associations with conditions that have known effects on brain function, and secondly, evidence from brain imaging.

Brain structure. Structural imaging in patients with OCD has revealed rather variable changes, but the most consistent is an increase in grey matter volume in certain parts of the brain. The symptoms of OCD are related to dysfunction in the well-described corticostriatal-thalamic loops, which support affective and reward processing, working memory and executive function, and motor and response inhibition.

Serotonin hypothesis. The finding that obsessive-compulsive symptoms respond to drugs that increase serotonin (a neurotransmitter, i.e., a naturally occurring chemical in the brain that facilitates transmission of signals between nerve cells) function suggests that serotonin mechanisms might be abnormal in OCD.

Psychoanalytical theories. They are not supported by evidence, and these theories are only of historical importance. They suggest that obsessional symptoms result from unconscious impulses of an aggressive or sexual nature. These impulses could potentially cause extreme anxiety, but anxiety is reduced by the action of the defense mechanisms of repression and reaction formation.

Neuropsychological function. Compulsivity has been contrasted with impulsivity, which is seen as a failure to inhibit inappropriate behaviors that are driven by reward and gratification. A tendency to compulsive responding can be detected by neuropsychological tasks that require an altered response once a ‘habit’ has been established by previous learning. A similar abnormality has been detected in first-degree relatives of OCD patients. This suggests that, in these people, actions may be mediated by a relative preponderance of habit learning over goal-directed learning. This might underpin the development of compulsive behaviors.

Cognitive theory. This theory is based on the premise that it is not the occurrence of intrusive thoughts that has to be explained (as these are experienced at times even by healthy people), but rather the obsessional patient’s inability to control them and see them in perspective. For example, people with obsessional disorder often respond to such thoughts as if they were personally responsible for their possible consequences (e.g. for harm to another person). It is suggested that this feeling of responsibility leads to excessive attempts to ward off the thoughts and their supposed consequences by adopting compulsive behaviors and avoidance, and seeking repeated reassurance.

Diagnosis of OCD

  • Presence of obsessions, compulsions, or both:
    • Obsessions are defined by both: (1) Recurrent and persistent thoughts, urges, or images that are intrusive and unwanted, and cause marked anxiety or distress, and (2) The individual attempts to ignore or suppress, or to neutralize them with some other thought or action (i.e., by performing a compulsion).
    • Compulsions are defined by both: (1) Repetitive behaviors (e.g., hand washing, ordering, and checking) or mental acts (e.g., praying, counting, repeating words silently) that the individual feels compelled to perform in response to an obsession or according to rigid rules. (2) The behaviors or mental acts are aimed at preventing or reducing anxiety or distress, or preventing some dreaded event or situation; however, these behaviors or mental acts are unrealistic in their efficacy, or are clearly excessive.
    • Note: Young children may not be able to articulate the aims of these behaviors or mental acts.
  • The obsessions or compulsions are time-consuming (e.g., take more than 1 hour per day) or cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.
  • The obsessive-compulsive symptoms are not attributable to a drug of abuse or a medication or another medical condition.
  • The disturbance is not better explained by the symptoms of another mental disorder, such as body dysmorphic disorder; hoarding disorder; trichotillomania (hair-pulling disorder); excoriation (skin-picking) disorder; stereotypic movement disorder; eating disorders; substance-related and addictive disorders; illness anxiety disorder; paraphilic disorders; disruptive, impulse-control, and conduct disorders; major depressive disorder; schizophrenia spectrum and other psychotic disorders; or autism spectrum disorder.

Treatment of OCD


Clomipramine. It is not now used as a first-line agent. It is a tricyclic antidepressant. It is more effective than placebo in reducing the obsessional symptoms of patients with OCD. Most patients tolerate the treatment, but typical tricyclic side effects are common, and at high doses a few patients develop seizures. Effects are seen only after about 6 weeks of treatment, and further improvement may take another 6–12 weeks. Many patients relapse during the first few weeks after the drug is stopped, but the relapse rate is reduced if clomipramine is combined with exposure, and if drug treatment is maintained.

Selective serotonin uptake inhibitors (SSRIs). SSRIs are effective in reducing obsessional symptoms, although individual patients may respond better to one SSRI than another. Higher doses are somewhat more efficacious. Overall, SSRIs appear to have similar efficacy to clomipramine. However, clomipramine treatment is associated with more dropouts from treatment.

Since only about 50% of the treated patients improve substantially with the SSRI, a second drug is usually added, typically an antipsychotic agent, usually at a low dose. Both typical and atypical antipsychotics are effective, but the latter have fewer side effects. A meta-analysis suggested that significant, albeit modest, benefit was most likely with the addition of low doses of risperidone and aripiprazole.

Since relapse is common during the first few weeks after an SSRI has been stopped, longer-term maintenance treatment is advisable.

Anxiolytic drugs. These drugs give some short-term symptomatic relief but should not be prescribed continuously for more than 2–4 weeks at a time as they can be habit-forming.

Cognitive Behavior Therapy

Exposure and response prevention. Obsessional rituals usually improve with a combination of response prevention and exposure to any environmental cues that increase the symptoms. When rituals respond to this treatment, the accompanying obsessional thoughts usually improve as well.

Behavioral treatment is less effective for obsessional thoughts that occur without rituals. The technique of thought-stopping has been used for many years, but there is not much evidence that it has a specific effect.

Cognitive therapy. This therapy seeks to reduce the patient’s attempts to suppress and avoid obsessional thoughts, as such attempts have been shown to increase, rather than decrease, the frequency of these thoughts.

The patient is helped to record the frequency of obsessional thoughts to compare the effects of suppression and distraction. As suppression and avoidance appear to be driven by the conviction that to think something is to make it happen, attempts are made to weaken this conviction by reviewing the evidence for and against it.

Neurosurgery and Deep Brain Stimulation

The immediate result of neurosurgery for severe OCD is often a striking reduction in tension and distress. However, the long-term effects are uncertain.

Deep brain stimulation (DBS) has also been employed to treat intractable OCD. However, current worldwide experience is still limited.


American Psychiatric Association, 2013. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Washington, DC: American Psychiatric Publishing.

Harrison, P., Cowen, P., Burns, T. & Fazel, M., 2018. Shorter Oxford Textbook of Psychiatry. 7 ed. Oxford: Oxford University Press.

Sadock, B. J., Sadock, V. A. & Ruiz, P., 2017. Kaplan and Sadock’s Comprehensive Textbook of Psychiatry. 10th ed. Philadelphia: Wolters Kluwer.

Tasman, A. et al. eds., 2015. Psychiatry. 4th ed. Oxford: Wiley Blackwell.


Obsessive-Compulsive Disorder (OCD): Symptoms and Treatment
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Obsessive-Compulsive Disorder (OCD): Symptoms and Treatment
Obsessive-compulsive disorder (OCD) is characterized by repetitive, intrusive, anxiety-provoking thoughts, and behaviors to relieve that anxiety.
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