Causes of Obsessive Compulsive Disorder

The causes of obsessive compulsive disorder are not fully understood and there is unlikely one single theory, either biological or psychological that provides a comprehensive explanation for the development of OCD. Theories about the causes of OCD fall into the following categories:

• Serotonin hypothesis
• Dopamine hypothesis
• Autoimmune hypothesis
• Psychological models
• Genetic models

According to the serotonin hypothesis it is claimed that OCD may result from disturbances in the brain neurotransmitter serotonin. This theory is supported by some studies showing that antidepressants targeting serotonin (SSRI) can help alleviate many symptoms of OCD. However, studies directly investigating serotonin levels in OCD sufferers have been inconclusive. SSRI's are also shown to be of no benefit to 40 percent of sufferers (with a significant portion of the remaining 60 percent realising only mild benefits).

According to the dopamine hypothesis, it is argued that dysregulation in the brain neurotransmitter dopamine may be one of the causes of obsessive compulsive disorder, particularly in those suffering from tics (sudden, repetitive, nonrhythmic, stereotyped motor movement). Such OCD sufferers have been shown to benefit from drugs that increase dopamine but experience little change when prescribed medications that increase serotonin.

Another theory proposed as one of the causes for obsessive compulsive disorder is the autoimmune hypothesis. This hypothesis is based on studies showing that in children, OCD begins after infection with streptococcus (strep throat). The term used to describe this subset of children is 'pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections' (PANDAS). This theory remains controversial and requires further research.

The genetic hypothesis is supported by research showing that genes may play a role as one of the causes of obsessive compulsive disorder, however, no specific gene/s for OCD have been identified.  Childhood-onset OCD runs in families (sometimes in association with tic disorders) and when a parent has OCD, there is a slightly increased risk that a child will develop OCD, although the risk is still relatively low.

Psychological theories fall into two categories: behavioural and cognitive models. According to behavioural theories, people with OCD associate certain objects or situations with fear, and then learn to avoid the things they fear, or to perform rituals that help reduce the fear. This pattern of fear and avoidance/ritual may begin when people are under periods of high stress, such as starting a new job, parenthood or ending a relationship. Once a connection between an object and the feeling of fear becomes established, people with OCD avoid the things they fear, rather than confront or tolerate the fear. The association of fear may then spread to other objects or situations.

According to cognitive theory, while most people have intrusive or uninvited thoughts similar to those reported by people with OCD, OCD sufferers exaggerate the importance of the thought, and respond as though it represents an actual threat. This causes anxiety and distress for the person so he/she attempts to neutralise the feeling by doing such things as avoiding situations that might set off such thoughts. Another way is by engaging in rituals, such as washing or praying.

According to cognitive theory, the following beliefs may be important in the development and maintenance of obsessions:

• the belief that one is responsible for preventing misfortunes or harm to others
• the belief that certain thoughts are very important and should be controlled
• the belief that somehow having a thought or an urge to do something will increase the chances that it will come true
• the tendency to overestimate the likelihood of danger
• the belief that one should always be perfect and that mistakes are unacceptable.

As outlined in this article, there are a number of models that attempt to explain the causes of obsessive disorder. While many of these models have some support in research no one theory accounts as the sole causes of OCD. OCD is likely caused by a range of factors and can vary across sufferers. What may cause OCD in one person may be totally different for another person. Therefore comprehensive assessment is important to help determine the most appropriate treatment.
 

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