Like many mental health conditions, the severity of obsessive-compulsive disorder or OCD can vary from person to person. Some may only experience mild symptoms while for others, the disorder can be debilitating.
OCD is characterised by intrusive thoughts and compulsion-driven obsessions that the sufferer needs to carry out to soothe their anxiety. Much research has been done about the genetic factor influencing OCD and whether there is a specific gene influencing the disorder. Here’s what researchers know about the link between OCD and genetics.
Genetics plays an important factor, but it is not the sole factor.
Researchers agree that genetics contribute to the overall risk of OCD. However, according to Christopher Pittenger, PhD, Director of the Yale OCD Research Clinic, genetics does not completely determine whether an individual is going to have the disorder or not.
A 2013 study looked at 2,057 pediatric and adolescent OCD patients and compared them against a control group of 6,055 people without OCD. The researchers found that a person is more likely to occur if they had a family member with OCD. They were also more likely to have OCD if they had an immediate family member with tic disorder, affective disorder, or anxiety disorder.
The link between OCD and genetics was further examined through a study that looked at twins with OCD in 2014. The study analysed 5,409 pairs of twins and discovered that 52% of identical twins both had OCD whereas 21% of fraternal twins both had OCD. Through these findings, the researchers inferred that the higher amount of DNA shared between family members, the higher the chances of a co-occurrence of OCD. They determined that the heritability or genetic risk for OCD is around 48%.
Despite this knowledge, researchers are still trying to identify the specific gene that causes OCD. Pittenger says that the genome-wide association studies or GWAS that have already been conducted were too small to determine the gene. He believes a study at least 10 times larger is needed to find the genetic hits, which might happen in the near future.
The Other 52%
As established prior, genetics is, indeed, a significant factor that determines an individual’s risk to develop OCD. But OCD is only partially genetic and it is important to understand the other risk factors that could lead to the development of the condition. Some of the risk factors include:
- Childhood trauma and stress could contribute to OCD, but the exact logistics are not yet known. Pittenger says that this factor may not be specific as childhood stress and trauma are known to increase the risk of many mental disorders.
- The National Institute of Mental Health believes that people with OCD have differences in brain structure and functioning. However, more research should be conducted to draw a conclusion about this theory.
- OCD is also linked to PANDAS or pediatric autoimmune neuropsychiatric disorder, which is associated with streptococcus. According to Pittenger, the induced autoimmune process in the disorder could trigger a sudden onset of OCD symptoms. Again, more research is needed to confirm the link between the disorders.
- The major hormonal changes, particularly the sudden increase of the hormone oxytocin, that occur in the body during pregnancy and post-pregnancy are also thought to be able to trigger OCD.
- OCD also seems to be linked to autism. According to a 2015 study in PLoS One, people diagnosed with an autism spectrum disorder had a higher risk of developing OCD.
- Finally, OCD is also associated with other mental health conditions. In fact, OCD rarely occurs alone and often co-occurs with other conditions such as anxiety disorders, phobias, major depressive disorder, substance abuse, attention deficit disorders, and tic disorders.
It is already established that genetics contributes greatly to the development of OCD, but it is not the only contributor. It is important to recognise the other risk factors that could trigger an individual to develop the disorder.
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