Obsessive Compulsive Disorder Causes & Risk Factors

Obsessive-compulsive disorder is a complex condition that is being studied for a better understanding. However, its exact causes are not fully understood, but studies point to a combination of biological and environmental factors.

Biological factors: Studies have revealed that individuals with OCD have an insufficient level of seretonin, one of the brain's neurotransmitters. This result is supported by the efficacy of serotonin reuptake inhibitors (SSRI's) in the treatment of OCD. Other studies also reveal that some individuals with OCD have abnormalities in dopaminergic transmission.

Recent imaging studies discovered an abnormal pattern of activity in certain area of the brain in individuals with OCD. Magnetic resonance imaging and positron emission tomography revealed that there is an increased blood flow and metabolic activity in the orbitofrontal cortex, limbic structures, caudate, and thalamus, with a trend toward right-sided predominance of the individuals with OCD. This overactivity can be brought to normal when the individual is treated with serotonin reuptake inhibitors or cognitive-behavioral therapy.

Whether the disorder is inherited or not, scientists have not reached a final conclusion. However, there is strong evidence which indicates OCD might be inherited. Studies conducted on twins have shown a significantly higher concordance rate in monozygotic twins (80 to 87 percent) than in dizygotic twins (47 to 50 percent). Approximately 35 percent of first-degree relatives of individuals with an childhood onset OCD, are affected by the disorder. Also, a person with OCD has a 25 percent chance of having a blood relative that also has the disorder.

Obsessive-compulsive disorder has a strong genetic component. However, the genetic mechanism of OCD is not fully understood and identified. Recent studies revealed some genes that can be associated with OCD. One of them is a glutamate transporter gene called SLC1A1. This gene encodes a protein, called EAAC1, that regulates the flow of glutamate in and out of the brain cells. Glutamate is the key molecule in cellular metabolism and the most abundant swift excitatory neurotransmitter in the nervous system. Variations of this gene is believed to cause alterations in the glutamate flow and therefore increase the risk of obsessive-compulsive disorder. These findings are supported by imaging studies that have identified differences in the glutamate system in individuals with OCD, than the normal population. Another gene associated with OCD is human serotonin transporter gene (hSERT). This gene controls how the body uses serotonin, one of the brain's neurotransmitter which is involved in mood control, aggression, body temperature, sleep, anger, sexuality, and appetite.

Another gene associated with OCD is myelin oligodendrocyte glycoprotein (MOG) gene involved in the autoimmune system. This gene was discovered in a group of children diagnosed with pediatric autoimmune neuropsychiatric disorder associated with a beta-hemolytic streptococcal pharyngitis infection (strep throat). Scientist believe that an antibody against this infection sometimes act like a brain enzyme disrupting the communication between the brain neurons and leading to OCD. However, the final conclusions was not reached yet and more studies are being conducted on this subject.

Obsessive-compulsive disorder is also associated with a mutation on several dopamine receptor genes DRD2, DRD3, DRDD4, serotonin 2A receptor 5HT2A, 5HT1Dbeta receptor gene (involved in the serotonin system), and brain-derived neurotrophic factor (BDNF)gene (a protein active in hippocampus, cortex, basal forebrain, and peripheral nervous system).

Some researchers share the belief that OCD can be triggered by changes in the body's natural chemistry. Studies have shown that pregnant women and new mothers are at a higher risk to develop OCD. In these cases, the OCD symptoms are triggered by thoughts of harming the baby.

Environmental factors: There are environmental factors that can trigger the disorder in individuals psychologically prone for OCD. Some of these symptoms include:

Conditions & Diseases: Psychological & Mental Health

Obsessive-Compulsive Disorder