Causes of Obsessive-Compulsive Disorder

Obsessive-compulsive disorder (OCD) is a mental illness characterized by intrusive, disturbing thoughts, and compulsive, repetitive behaviors. Exactly what causes this is unknown, but abnormalities in brain structure, function, and chemistry have been observed in patients with OCD. It is also well documented that family history is the biggest risk factor for OCD, suggesting there is a genetic component. Contributing factors to the development of OCD may include childhood infections, stressful situations, and traumatic experiences.

Obsessive-compulsive disorder (OCD) is a very serious mental illness that can have a far-reaching impact on a person’s life. This condition causes persistent, troubling thoughts or obsessions. These vary by individual but may include thoughts of harming someone, violent images, or fears of being contaminated by germs. The thoughts are nearly impossible to stave off and cause significant distress.

OCD also causes compulsions, which are repetitive, ritual-like behaviors that a person performs to mitigate the distress of the obsessions or to prevent them from coming true. Compulsions may include counting objects, excessive hand washing, or checking and rechecking things, like door locks. Obsessions and compulsions cause distress and significant impairment. They take up time and take focus away from other areas of a person’s life.

OCD can be successfully managed with good treatment. Residential care with ongoing therapy can help patients face the thoughts they fear and learn to control them while also managing and reducing compulsions. Antidepressants, stress management, social support, and self-care can also help. Causes of OCD are not fully understood, but research has uncovered many facts about how this disease develops and who is more susceptible.

Genetics and Family History


As with most mental illnesses, family history is the biggest predictor for whether or not someone will develop OCD. Studies of families and twins show that there is a strong genetic association for OCD. The risk of having the condition is much higher for those who have a first-degree relative—parent, child, or sibling—and even higher for those who have an identical twin with OCD. An individual who has an identical twin with the condition has 80 to 87 percent chance of also having OCD.

The family history connection strongly suggests that there is a gene or group of genes associated with the development of OCD. However, no studies have yet been able to pinpoint any part of the DNA that corresponds to the condition. Because people with OCD respond well to treatment with antidepressants that target the brain chemical serotonin, there may be genes associated with serotonin that play a role in OCD development.

OCD and Brain Chemistry and Structure


Most mental illnesses have been tied in some way to the chemicals in the brain or to alterations in activity or structures in the brain. Neurotransmitters, the chemicals that are used as signaling molecules between neurons, play a big role in many conditions, like depression, anxiety disorders, and OCD. Changes, deficiencies, or other abnormalities in these chemicals certainly play a role in many mental illnesses. Brain chemistry has long been an area of study for researchers trying to determine what causes OCD.

Serotonin is a prime candidate for a potential cause or contributing factor to OCD. Antidepressant medications that increase the amount of serotonin in the brain, called SSRIs, work well for most people with OCD. This may mean that a deficiency in serotonin contributes to OCD, although it is probably not the single cause for any one person with the condition.

With imaging scans of the brain, researchers have been able to determine that there are three areas or structures in the brain that are more active in people with OCD. This further indicates that brain abnormalities are implicated as contributing causes. The three areas of the brain that are overactive are:

  • The caudate nucleus. This part of the brain is associated with filtering thoughts and managing habits. When OCD is well managed with treatment, activity in this area goes down.
  • The prefrontal orbital cortex. This area is associated with managing appropriate social behaviors. Decreased activity here leads to lowered inhibitions, but increased activity can cause social anxiety and worries about cleanliness or acting inappropriately.
  • The cingulate gyrus. Located in the center of the brain, this region is thought to regulate how a person reacts to troubling thoughts and obsessions. Over-activity here may trigger compulsive behaviors.

The most recent OCD research has implicated yet another brain chemistry factor that could explain the condition. Researchers working with laboratory mice investigated a protein called SPRED2. Found in all cells in the body, it is especially concentrated in the brain. When the protein was eliminated from the mice, it triggered compulsive and excessive grooming. The researchers hope that by targeting this protein and the chemical pathways it triggers, they can develop a better treatment for OCD.

OCD and Trauma


Brain chemistry, activity, and structure are known to underlie the development of OCD, but what causes the abnormalities in the brain are not known. While genetics almost certainly play a role, specific genes have not been found, and it is not understood why some people with a family history of the condition will develop it while others will not.

One explanation is that there are other risk factors that contribute to OCD. Trauma, for instance, seems to be a risk factor that makes it more likely someone will develop OCD, especially if that individual also has a family history of the condition. Trauma in childhood may be particularly damaging and may include neglect, abuse, sexual assault, bullying, witnessing violence, being in a serious accident, or many other frightening experiences.

Trauma in adulthood may also trigger OCD. Studies of adults with both OCD and post-traumatic stress disorder (PTSD) found that the compulsions of OCD are used to mitigate distress caused by memories of trauma. When patients received treatment for OCD and the related behaviors decreased, the PTSD symptoms worsened. Studies have also found that people sometimes develop OCD after a traumatic event, and that when they do the symptoms are often more severe. This research suggests that trauma can definitely play a role in causing OCD.

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The Role of Stress in the Development of OCD


Stress may also play a role in OCD, although whether or not it can actually cause the condition is not known. There is evidence that OCD onset is more likely during a period of high stress in a person’s life. This does not mean, however, that stress causes OCD, but it may trigger its onset in someone predisposed to the condition, or it may worsen symptoms in someone who already has it. The explanation may be that during times of stress, a person is more susceptible to irrational fears and obsessive thoughts and worries.

Streptococcal Infection in Kids and OCD


In some cases of OCD, disease may trigger its onset. The mechanism is not fully understood, but experts believe streptococcal infections can trigger symptoms of OCD, or an early onset of the condition, in children who are already predisposed to it. When this happens a child may be diagnosed with PANDAS, which stands for pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections. The infection triggers an autoimmune response that affects the brain in some way, triggering OCD.

The diagnosis of PANDAS is given when a child begins to exhibit signs of OCD immediately after an infection, if that child never had such symptoms before. It may also be diagnosed if the child had some symptoms of OCD but they get much worse right after an infection. Streptococcal infections that may trigger PANDAS include strep throat and scarlet fever. PANDAS may occur in children between the age of about three and the onset of puberty. Signs of PANDAS in children may vary by individual, but typical symptoms include:

  • Any OCD symptoms
  • Signs of a tic disorder, including vocal or movement tics
  • Moodiness and irritability
  • Separation anxiety
  • Hyperactivity and inattention
  • Difficulty sleeping
  • Bed wetting
  • Joint pain
  • Changes in motor skills

Causes of OCD are still not fully understood, but researchers have developed a fairly clear picture of what happens in the brain of someone with this condition. They have also determined that there are strong risk factors for OCD, including family history and trauma. Regardless of what causes OCD, the repercussions of living with this condition can be serious.

It is important for anyone struggling with OCD to understand that there is hope through treatment. With dedicated therapy, often best conducted during an extended stay in residential care, medications, self-care, and positive support, the prognosis for living with OCD and managing symptoms is good.