Obsessive-compulsive disorder (OCD) is characterized by distressing, intrusive obsessive thoughts and/or repetitive compulsive physical or mental acts. Once believed to be rare, OCD was found to have a lifetime prevalence of 2.5% in the Epidemiological Catchment Area study. 
Signs and symptoms
Common obsessions include the following:
Doubting one's memory or perception
Scrupulosity (need to do the right thing, fear of committing a transgression, often religious)
Need for order or symmetry
Unwanted, intrusive sexual/aggressive thoughts
Common compulsions include the following:
Checking (eg, locks, stove, iron, safety of children)
Counting/repeating actions a certain number of times or until it "feels right"
Many patients with OCD have other psychiatric comorbid disorders, and may exhibit any of the following:
Mood and anxiety disorders
Somatoform disorders, especially hypochondriasis and body dysmorphic disorder
Impulse control disorders, especially kleptomania and trichotillomania
Attention deficit–hyperactivity disorder (ADHD)
Obsessive-compulsive personality disorder
Suicidal thoughts and behaviors
Skin findings in OCD patients may include the following:
Eczematous eruptions related to excessive washing
Hair loss related to trichotillomania or compulsive hair pulling
Excoriations related to neurodermatitis or compulsive skin picking
See Clinical Presentation for more detail.
Once OCD is suspected, the following should be performed:
Define the range and severity of OCD symptoms; the Yale-Brown Obsessive Compulsive Scale (Y-BOCS)  is a good tool for this purpose
Complete Mental Status Examination; look for comorbid symptoms and disorders
The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5),  released in 2013, includes a new chapter for OCD and related disorders, including body dysmorphic disorder, hoarding disorder, trichotillomania, and excoriation disorder. Previously, OCD was grouped together with anxiety disorders.
The American Psychiatric Association defines OCD as the presence of obsessions, compulsions, or both. Obsessions are defined by (1) and (2) as follows:
- Recurrent and persistent thoughts, urges, or images that are experienced, at some time during the disturbance, as intrusive and unwanted, and cause marked anxiety and distress
- The person attempts to suppress or ignore such thoughts, impulses, or images or to neutralize them with some other thought or action
Compulsions are defined by (1) and (2) as follows:
- Repetitive behaviors (eg, hand washing, ordering, checking) or mental acts (eg, praying, counting, repeating words silently) in response to an obsession or according to 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 way that could realistically neutralize or prevent whatever they are meant to address, or they are clearly excessive
See Workup for more detail.
The mainstays of treatment of OCD are as follows:
Serotonergic antidepressant medications
Particular forms of behavior therapy (exposure and response prevention and some forms of cognitive-behavioral therapy [CBT])
Education and family interventions
Neurosurgery (anterior capsulotomy, or deep brain stimulation)  , in extremely refractory cases
First-line serotonergic antidepressants for OCD are selective serotonin reuptake inhibitors (SSRIs; (fluoxetine, fluvoxamine, sertraline, paroxetine, citalopram, escitalopram) and clomipramine (Anafranil), a tricyclic antidepressant. SSRIs are generally preferred over clomipramine, as their adverse effect profiles are less prominent. Results of serotonergic antidepressant treatment are as follows:
Complete or near-complete remission of OCD symptoms is rare with monotherapy
Perhaps half of patients may experience symptom reductions of 30-50%
Many other patients fail to achieve even this degree of relief
Interventions for patients with treatment resistance include the following:
Change or increase in medication (eg, increase dose or prescribe a different SSRI or clomipramine)
More intensive CBT
Other interventions, which have not received US Food and Drug Administration (FDA) approval for use in OCD, include the following:
Addition of a norepinephrine reuptake inhibitor (eg, desipramine) to an SSRI or a trial of venlafaxine
Addition of a typical or atypical antipsychotic (eg, haloperidol, olanzapine, risperidone), especially in patients with a history of tics
Augmentation with buspirone
Augmentation with ondansetron 
Addition of inositol
Obsessive-compulsive disorder (OCD) is a relatively common, if not always recognized, chronic disorder that is often associated with significant distress and impairment in functioning. Due to stigma and lack of recognition, individuals with OCD often must wait many years before they receive a correct diagnosis and indicated treatment.
OCD has a wide range of potential severity. Many patients with OCD experience moderate symptoms. In severe presentations, this disorder is quite disabling and is appropriately characterized as an example of severe and persistent mental illness.
Previously identified by the American Psychiatric Assocation as an anxiety disorder, OCD is now a separate diagnosis with its own chapter, "Obsessive-Compulsive and Related Disorders," in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). The condition is characterized by distressing, intrusive, obsessive thoughts and/or repetitive, compulsive actions (which may be physical or mental acts) that are clinically significant.
The new chapter groups OCD with related disorders, including body dysmorphic disorder, and conditions formerly found in the "impulse control disorder (ICD) not elsewhere classified" section, including trichotillomania.
DSM-5 criteria for obsession
Obsessions are defined in the DSM-5 by (1) and (2) as follows: 
Recurrent and persistent thoughts, urges, or images that are experienced, at some time during the disturbance as intrusive and inappropriate, and that cause marked anxiety and distress.
The person attempts to suppress or ignore such thoughts, impulses, or images or to neutralize them with some other thought or action.
DSM-5 criteria for compulsion
Compulsions are defined by (1) and (2) as follows:
Repetitive behaviors (eg, hand washing, ordering, checking) or mental acts (eg, praying, counting, repeating words silently) performed in response to an obsession or according to rules that must be applied rigidly. The behaviors are not a result of the direct physiologic effects of a substance or a general medical condition.
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 way that could realistically neutralize or prevent whatever they are meant to address or they are clearly excessive.
At some point during the course of the disorder, the person recognizes that the obsessions or compulsions are excessive or unreasonable (although this does not apply to children).
The obsessions or compulsions cause marked distress, are time consuming (take >1 hour per day), or significantly interfere with the person's normal routine, occupational or academic functioning, or usual social activities or relationships.
Obsessions and their related compulsions (the latter also referred to as rituals) often fall into 1 or more of several common categories, as seen in the table below.
Table. Categorizing Obsessions and Compulsions (Open Table in a new window)
|Obsessions||Commonly Associated Compulsions|
|Fear of contamination||Washing, cleaning|
|Need for symmetry, precise arranging||Ordering, arranging, balancing, straightening until "just right"|
|Unwanted sexual or aggressive thoughts or images||Checking, praying, “undoing” actions, asking for reassurance|
|Doubts (eg, gas jets off, doors locked)||Repeated checking behaviors|
|Concerns about throwing away something valuable||Hoarding|
Individuals often have obsessions and compulsions in several categories, and may have other obsessions (eg, scrupulosity, somatic obsessions, physical or mental repeating rituals). Often, the first pathologic obsession that an individual may experience is fear of contamination.
DSM-5 includes 2 new diagnoses in OCD: excoriation (skin-picking) disorder and hoarding disorder. Excoriation disorder is characterized by repetitive and compulsive picking of skin, resulting in tissue damage. Hoarding is a disorder in which sufferers have persistent difficulty discarding possessions regardless of their value. [14, 15]
OCD should not be confused with obsessive-compulsive personality disorder (OCPD). The diagnosis of OCPD refers to an individual who is preoccupied with orderliness, perfectionism, and mental and interpersonal control, at the expense of flexibility, openness, and efficiency; a pattern that typically emerges in early adulthood. They often display perfectionism, excessive devotion to work, rigidity, and/or miserliness (for further details, see DSM-5). 
Despite the similarities in labels, relatively few individuals with OCD also meet the criteria for OCPD and vice versa.
The fact that obsessive-compulsive symptoms seem to often take very stereotypic forms has led some to hypothesize that the pathologic disturbance causing OCD may be disinhibiting and exaggerating some built-in behavioral potential that humans have that, under other ancestral circumstances, would have an adaptive function (eg, primate grooming rituals).
The exact process that underlies the development OCD has not been established. Research and treatment trials suggest that abnormalities in serotonin (5-HT) neurotransmission in the brain are meaningfully involved in this disorder. This is strongly supported by the efficacy of serotonin reuptake inhibitors (SRIs) in the treatment of OCD. [16, 17]
Evidence also suggests abnormalities in dopaminergic transmission in at least some cases of OCD. In some cohorts, Tourette disorder (also known as Tourette syndrome) and multiple chronic tics genetically co-vary with OCD in an autosomal dominant pattern. OCD symptoms in this group of patients show a preferential response to a combination of serotonin specific reuptake inhibitors (SSRIs) and antipsychotics. 
Functional imaging studies in OCD have demonstrated some reproducible patterns of abnormality. Specifically, magnetic resonance imaging (MRI) and positron emission tomography (PET) scanning have shown increases in blood flow and metabolic activity in the orbitofrontal cortex, limbic structures, caudate, and thalamus, with a trend toward right-sided predominance. In some studies, these areas of overactivity have been shown to normalize following successful treatment with either SSRIs or cognitive-behavioral therapy (CBT). 
These findings suggest the hypothesis that the symptoms of OCD are driven by impaired intracortical inhibition of specific orbitofrontal-subcortical circuitry that mediates strong emotions and the autonomic responses to those emotions. Cingulotomy, a neurosurgical intervention sometimes used for severe and treatment-resistant OCD, interrupts this circuit (see Treatment and Management).
Similar abnormalities of inhibition are observed in Tourette disorder, with a postulated abnormal modulation of basal ganglia activation.
Attention has also been focused on glutamatergic abnormalities and possible glutamatergic treatments for OCD. [20, 21] Although modulated by serotonin and other neurotransmitters, the synapses in the cortico-striato-thalamo-cortical circuits thought to be centrally involved in the pathology of OCD principally employ the neurotransmitters glutamate and gamma-aminobutyric acid (GABA).
Genetic influence in OCD
Twin studies have supported strong heritability for OCD, with a genetic influence of 45-65% in studies in children and 27-47% in adults.  Monozygotic twins may be strikingly concordant for OCD (80-87%), compared with 47-50% concordance in dizygotic twins.  Several genetic studies have supported linkages to a variety of serotonergic, dopaminergic, and glutamatergic genes. [24, 25, 26, 27, 28]
Other genes putatively linked to OCD have included those coding for catechol-O-methyltransferase (COMT), monoamine oxidase-A (MAO-A), brain-derived neurotrophic factor (BDNF), myelin oligodendrocyte glycoprotein (MOG), GABA-type B-receptor 1, and the mu opioid receptor, but these must be considered provisional associations at this time. In some cohorts, OCD, attention deficit hyperactivity disorder (ADHD), and Tourette disorder/tic disorders co-vary in an autosomal dominant fashion with variable penetrance.
Infectious disease and OCD
Case reports have been published of OCD with and without tics arising in children and young adults following acute group A streptococcal infections. Fewer reports cite herpes simplex virus as the apparent precipitating infectious event.
It has been hypothesized that these infections trigger a CNS autoimmune response that results in neuropsychiatric symptoms (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections [PANDAS]). A number of the poststreptococcal cases have reportedly improved following treatment with antibiotics.
Other neurologic conditions
Rare reports exist of OCD presenting as a manifestation of neurologic insults, such as brain trauma, stimulant abuse, and carbon monoxide poisoning.
Stress and OCD
OCD symptoms can worsen with stress; however, stress does not appear to be an etiologic factor.
Parenting and OCD
As previously mentioned, parenting style or upbringing does not appear to be a causative factor in OCD.
Incidence of OCD in the United States
Once believed to be rare, OCD was found to have a lifetime prevalence of 2.5% in the Epidemiological Catchment Area study.  Current estimates of lifetime prevalence are generally in the range of 1.7-4%. Discovery of effective treatments and education of patients and health care providers have significantly increased the identification of individuals with OCD. The incidence of OCD is higher in dermatology patients and cosmetic surgery patients.
Race-, age-, and sex-related demographics
OCD appears to have a similar prevalence in different races and ethnicities, although specific pathologic preoccupations may vary with culture and religion (eg, concerns about blaspheming are more common in religious Catholics and Orthodox Jews).
The overall prevalence of OCD is equal in males and females, although the disorder more commonly presents in males in childhood or adolescence and tends to present in females in their twenties. Childhood-onset OCD is more common in males. Males are more likely to have a comorbid tic disorder.
It is not uncommon for women to experience the onset of OCD during a pregnancy, although those who already have OCD will not necessarily experience worsening of their symptoms during pregnancy.
Women commonly experience worsening of their OCD symptoms during the premenstrual time of their periods. Women who are pregnant or breastfeeding should collaborate with their physicians in making decisions about starting or continuing OCD medications.Age preference in OCD
Symptoms of OCD usually begin in individuals aged 10-24 years.
OCD is a chronic disorder with a wide range of potential severities. Without treatment, symptoms may wax and wane in intensity, but they rarely remit spontaneously.
Overall, close to 70% of patients entering treatment experience a significant improvement in their symptoms. However, OCD remains a chronic illness, with symptoms that may wax and wane during the life of the patient.
Roughly 15% of patients can show a progressive worsening of symptoms or deterioration in functioning over time.
Approximately 5% of patients have a complete remission of symptoms between episodes of exacerbation.
Pharmacologic treatment is often prescribed on a continuing basis; if a successfully treated individual discontinues his/her medication regimen, relapse is not uncommon. However, patients who successfully complete a course of CBT (perhaps as few as 12-20 sessions) may experience enduring relief even after the treatment, although some evidence shows that having CBT continue in some extended but less frequent fashion may further decrease the risk of relapse.
A certain percentage of patients may have disabling, treatment-resistant symptoms. These patients may require multiple medication trials and/or referral to a research center. A small subgroup of these patients may be candidates for neurosurgical intervention.
Education about the nature and treatment of OCD is essential. As with many psychiatric disorders, patients and their families often have misconceptions about the illness and its management. Information should be provided about the neuropsychiatric source of the symptoms, as opposed to having families unnecessarily blame themselves for causing the disorder.
A helpful book on OCD, written for the general public, is Dr Judith Rapoport's The Boy Who Couldn't Stop Washing,  which discusses the recognition of OCD in individuals and the identification of effective treatments for the disease.
Patients and their families should be provided with information on support groups and should have opportunities to discuss the impact the illness has had on their self-experience and on their relationships.
The Obsessive-Compulsive Foundation is a self-help and family organization founded in 1986 that offers information and resources regarding OCD and related disorders (including contact information for various types of affiliated support groups, contact information listing psychiatrists and therapists who are experienced in the treatment of OCD, research opportunities, and book reviews).
Some other organizations offer more specialized resources, (eg, the San Francisco Bay Area Internet Guide for Extreme Hoarding Behavior, the Madison Institute of Medicine's Obsessive Compulsive Information Center, which provides information and a monthly newsletter for individuals with OCD symptoms of scrupulosity about religious/moral issues).
A more complete listing of OCD resources appears as an appendix in the APA Practice Guideline for OCD. 
Several self-help books are also available, including Dr Edna Foa and Dr Reid Wilson's book,  which can add CBT-style self-treatment to the educational experience they provide.
Useful Web sites include the following:
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