OCD Facts: What Causes OCD

What Causes OCD

OCD is a disorder that has a neurobiological basis.  Using neuroimaging technologies in which pictures of the brain and its functioning are taken, scientists have shown that certain areas of the brain function differently in individuals who have OCD than in those who do not.

Research findings suggest that several areas of the brain may be involved with the symptoms of OCD. These are the orbitofrontal cortex, the anterior cingulate cortex (both in the front of the brain), the striatum and thalamus (deeper parts of the brain).  The repeated unpleasant thoughts and feelings of OCD may be due to problems in communication among these brain areas.  It is not clear what the nature of these problems is, or the cause, but chemicals in the brain (such as serotonin, dopamine, and/or glutamate) appear to be involved.

Everyone's brain churns out random and strange thoughts.  Most children simply dismiss them and move on, but they get "stuck" in the brains of children with OCD.  These random thoughts are like the brain's junk mail.  Most people have a spam filter and can simply ignore junk mail that comes their way.  But having OCD is like having a spam filter that has stopped working -- the junk mail just keeps coming and it won't stop.  Soon, the junk mail seriously outnumbers the wanted mail, and the individual with OCD becomes overwhelmed.

The Gene Connection

A study funded by the National Institutes of Health examined DNA, and the results suggest that OCD and certain related psychiatric disorders may be associated with an uncommon mutation of the human serotonin transporter gene (hSERT).  People with severe OCD symptoms may have a second variation in the same gene.

Other research also points to a possible genetic component in OCD.  Family studies have demonstrated that OCD is significantly more common among relatives of children with OCD than in the relatives of controls (controls are the individuals in a study's comparison group who do not have OCD).  Thus, family history is a strong predictor of a child's developing OCD.  Interestingly, children often experience symptoms different from their parents or other family members, arguing against the case that OCD is the result of imitating others' symptoms.  A family history of tics or Tourette Syndrome has also been shown to increase the risk for OCD.  In addition, first-degree relatives (i.e., parents, siblings, and children) of individuals with OCD experience a significantly higher risk of developing OCD than the population at large.

Studies of twins provide further support for a genetic link to OCD.  Some research has indicated that, if one twin has OCD, the other is more likely to have OCD when the twins are identical, rather than fraternal. Research has also indicated that, when a child has blood relatives with OCD, anxiety disorders other than OCD, or tic disorders, the child is at greater risk of developing any of these disorders.

In general, studies of twins with OCD estimate that genetics contributes approximately 45-65% of risk for developing the disorder.  Thus, while genetics appears to be a risk factor for OCD, other factors such as environment also play a vital role.

Sudden Onset of OCD Symptoms

Note:  The information in this section is adapted from the article "Sudden and Severe Onset OCD - Practical Advice for Practitioners and Parents" by Dr. Michael Jenike and Susan Dailey. The full article is available on the main web site of Beyond OCD.

Some parents have reported that OCD symptoms occurred almost overnight, as if a switch were flipped; their child went to bed as the child they knew and woke up a stranger.  During the 1980s and 90s, Dr. Susan Swedo and her colleagues at the National Institute of Mental Health found that this sudden onset of symptoms in children was sometimes associated with strep infections.  It was theorized that strep antibodies were mistakenly attacking part of the brain known as the basal ganglia, resulting in OCD and/or tic symptoms in genetically-predisposed children.  This phenomenon came to be known as Pediatric Autoimmune Neuropsychiatric Disorders Associated with Strep, or PANDAS.

In the more recent past, researchers and clinicians have found that, although strep can be a trigger for OCD, it may not be the only trigger.  Non-strep diseases such as Lyme disease, mononucleosis and the flu virus (e.g., H1N1) could also cause similar neuropsychiatric illnesses in vulnerable children.  In July of 2010, researchers gathered at the National Institutes of Health to discuss the past decade of clinical findings.  Due to findings that triggers other than strep could lead to sudden-onset OCD, the researchers changed the name of the disease to Pediatric Acute-Onset Neuropsychiatric Syndrome, or PANS.  The two major criteria for PANS are:

1.  An abrupt and dramatic onset of OCD symptoms that is associated with significant impairment.  Panic attacks and unusual anxieties are also relatively common with PANS.  In addition to the usual obsessions and rituals associated with OCD, this criterion may also be fulfilled by the sudden onset of food avoidance, anorexia, and eating restrictions.  In young people with PANS, these symptoms may occur not only as isolated symptoms but also as difficulties associated with obsessive fears of choking, vomiting, or food that is contaminated.

2.  The simultaneous, rapid onset of other symptoms from at least two of the following seven categories:

     (a)  anxiety, especially separation anxiety and irrational fears

     (b)  emotional instability and/or depression

     (c)  irritability, aggression, and/or oppositional behaviors

     (d)  behavioral (developmental) regression

     (e)  sudden deterioration in school performance

     (f)  sensory or motor abnormalities, especially handwriting difficulties

     (g)  somatic, or physical signs and symptoms

Because a diagnosis of PANS is a clinical diagnosis and cannot be determined by lab or genetic tests, it is suggested that this diagnosis be determined by consensus of two experienced physicians.

Currently, PANDAS and PANS are extremely under researched.  Until the time that appropriate treatment targeted specifically at PANS is available, treatments traditionally implemented in the treatment of PANDAS (e.g., antibiotics, exposure and response prevention, selective serotonin reuptake inhibitors) may be beneficial, depending upon the individual needs of the child.

Other Factors That May Contribute to OCD

Several other factors may play a role in the onset of OCD.  Following is a discussion of behavioral, cognitive, and environmental factors that may contribute to OCD.


Learning theorists suggest that behavioral conditioning may contribute to the development and maintenance of obsessions and compulsions.  More specifically, they believe that compulsions are actually learned responses that help an individual reduce or prevent anxiety or discomfort associated with obsessions or urges.  A child who experiences an intrusive obsession regarding germs, for example, may engage in hand washing to reduce the anxiety triggered by the obsession.  Because this washing ritual temporarily reduces the anxiety, the probability that the child will engage in hand washing when a contamination fear occurs in the future is increased.  As a result, compulsive behavior not only persists but actually becomes excessive.


Many cognitive theorists believe that individuals with OCD have faulty or dysfunctional beliefs, and that it is their misinterpretation of intrusive thoughts that leads to the creation of obsessions and compulsions.  According to the cognitive model of OCD, everyone experiences intrusive thoughts.  People with OCD, however, misinterpret these thoughts as being very important, personally significant, revealing about one’s character, or having catastrophic consequences.  The repeated misinterpretation of intrusive thoughts leads to the development of obsessions.  Because the obsessions are so distressing, the individual engages in compulsive behavior to try to resist, block, or neutralize them.

The Obsessive-Compulsive Cognitions Working Group, an international group of researchers who have proposed that the onset and maintenance of OCD are associated with maladaptive interpretations of cognitive intrusions, has identified six types of dysfunctional beliefs associated with OCD:

1.  Inflated responsibility:  a belief that one has the ability to cause and/or is responsible for preventing negative outcomes;

2.  Overimportance of thoughts (also known as thought-action fusion):  the belief that having a bad thought can influence the probability of the occurrence of a negative event or that having a bad thought (e.g., about doing something) is morally equivalent to actually doing it;

3.  Control of thoughts:  a belief that it is both essential and possible to have total control over one’s own thoughts;

4.  Overestimation of threat:  a belief that negative events are very probable and that they will be particularly bad;

5.  Perfectionism:  a belief that one cannot make mistakes and that imperfection is unacceptable; and

6.  Intolerance for uncertainty:  a belief that it is essential and possible to know, without a doubt, that negative events won’t happen.


A number of environmental factors may contribute to the onset and maintenance of OCD.  Although some research suggests no link between negative life events and OCD, there are many reports in which childhood OCD has been triggered by a specific, often traumatic, event, including: the death of a loved one; the loss of a pet; a divorce in the family; a change in schools (e.g., going from elementary to middle school); a move to a new location (usually involving a change in schools; or unhappiness at school.  In addition, cognitive models of the causes of OCD support the idea that stress can increase intrusive thoughts, increasing the risk of obsessions.  Furthermore, a recent study indicated that one to two years prior to the onset of symptoms, both children and adults who develop OCD experience more negative life events than controls. Taken together, these results suggest that stress or trauma can play a role in the development of OCD among certain individuals.  And given the extraordinary levels of stress students sometimes experience in the home, school, and community, these findings are extremely important for education professionals.

Injuries also have been associated with OCD.  The results of one study, in which 80 children and adolescents who suffered a traumatic brain injury were examined, indicated that almost 30% of the young people had new onset obsessive compulsive symptoms within one year after the serious injury.

Another environmental factor that often has an impact on OCD is the involvement of the family.  In general, evidence specifically linking the onset of childhood OCD to family factors is absent.  With regard to the maintenance of OCD symptoms, however, family members (including parents, siblings and others) commonly play a role.

In an attempt to decrease the distress associated with OCD symptoms, family members frequently try to help, or accommodate, children with OCD.  Family accommodations may take many forms, such as: (1) providing verbal reassurance to excessive reassurance-seeking requests; (2) conducting rituals with or for the child (e.g., helping to check a stove, doing laundry); (3) providing items necessary to carry out rituals (e.g., supplying soap for hand washing); (4) allowing/helping the child avoid things that trigger OCD; and (5) allowing delays associated with ritual completion (e.g., waiting in the car to drive to school while the child completes washing rituals).

Although usually well-intentioned, family accommodation often leads to more severe symptoms and impairment.  Accommodating a child not only may have a negative impact on family dynamics but also may reinforce the child's future involvement in rituals and avoidance.  Thus, family members essentially enable the child, and symptoms worsen, rather than improve.  A worsening of OCD symptoms can also occur when family members respond to a child's rituals with criticism or hostility.


In sum, although the definitive cause or causes of OCD have not yet been identified, research continually produces new evidence that hopefully will lead to more answers.  It is likely, however, that a delicate interplay between various risk factors over time is responsible for the onset and maintenance of OCD.

What Doesn’t Cause OCD

Uninformed people are sometimes eager to find someone or something to “blame” for a child’s OCD.  Find out what doesn’t cause OCD, so you can help put a stop to erroneous information about OCD.

Learn What Doesn’t Cause OCD

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