- OCD is partially genetic, but researchers have been unable to locate a specific gene associated with OCD.
- Research on twins has estimated the genetic risk of OCD to be around 48%, which means that half of the cause of OCD is genetic.
- Other risk factors include childhood trauma, differences in brain function, the PANDAS condition, and having another mental illness.
- This article has been medically reviewed by Mayra Mendez, Ph.D., LMFTlicensed psychotherapist and program coordinator for intellectual and developmental disabilities and mental health services at Providence Saint John’s Child and Family Development Center in Santa Monica, California.
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Obsessive-compulsive disorder, or OCD, is a mental health condition that can be mild or debilitating. The condition is characterized by disturbing obsessions or intrusive thoughts as well as compulsions that must be performed in order to temporarily quell the anxiety caused by the distressing obsessions.
Over the years there has been much discussion about whether or not
is genetic and whether there is a specific gene linked to OCD. Here’s what you need to know about genetics and other risk factors for OCD.
OCD is partly genetic
OCD is partly genetic. “Genetics contribute to overall risk, but they don’t completely determine whether or not an individual will develop the disorder,” says Christopher Pittenger, PhD, director of the Yale OCD Research Clinic.
We’re a long way from having a clear understanding of the genetics of OCD, Pittenger says, but there are indirect approaches that researchers have used to learn more about the genetics of the disorder.
For example, a 2013 study published in Depression and Anxiety looked at 2,057 pediatric and adolescent patients with OCD compared to a control group of 6,055 people without OCD. The researchers found that OCD was much more likely to occur if a primary family member (parent, sibling, or offspring) had OCD. They were also more likely to have OCD if an immediate family member had a tic disorder, affective disorder, or anxiety disorder.
Another method of studying the genetics of OCD has been to examine twins with OCD. A 2014 review published in Psychiatric Clinics of North America studied 5,409 pairs of twins and found that 52% of identical twins (who share 100% of their DNA) both had OCD, while 21% of fraternal twins ( who share 50% of their DNA) both had OCD. This led the researchers to infer that the more DNA is shared between family members, the higher the likelihood that there is a co-occurrence of OCD. The study determined that the heritability (genetic risk) of OCD is about 48%, which means that half of the cause of OCD is genetic.
Researchers are still working to identify the specific gene(s) associated with OCD. Pittenger says genome-wide association studies, or GWAS, which have been done to try to find a gene, have been too small to determine if a gene exists.
“We probably need 10 times larger studies before we can hope to start finding robust genetic ‘hits’. Fortunately, there are two much larger GWAS studies underway,” says Pittenger. This means that in the near future we may have more answers regarding an OCD-related gene.
Other OCD risk factors
Since OCD is only partially genetic, there are other risk factors for developing the disease, however, Pittenger says that, as with the genetic aspect, other risk factors are not fully understood. more. Some of these risk factors include:
- Childhood stress and trauma: Pittenger says childhood stress and trauma can contribute to OCD, however, the exact logistics aren’t fully known. “My feeling is that this is a non-specific effect – childhood stress and trauma are bad, and they increase the risk for a range of different symptoms/diagnoses,” says Pittenger.
- Differences in brain function: According to the National Institute of Mental Health, there may be differences in brain structure and function in areas of the brain such as the frontal cortex in people with OCD. However, research on this is sparse and more studies need to be done to draw a conclusion.
- PANDAS (Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcus): PANDAS is a rare condition that has been linked to OCD. Pittenger says the autoimmune process induced in this disorder can trigger a sudden onset of OCD symptoms. A 2008 study published in Development and Psychopathology confirmed a link between post-PANDAS structural and functional brain changes and OCD, but more research is needed.
- Pregnancy: During pregnancy and after childbirth, there are major changes in the hormones of the body, and it is thought that this can trigger OCD. Sudden increases in levels of the hormone oxytocin are thought to be responsible.
- Autism: Autism and OCD seem to be linked. A 2015 study published in PLoS One found that people diagnosed with autism spectrum disorder had a double risk of also developing OCD.
- Have another mental health problem: OCD very rarely occurs alone. In fact, about 90% of patients with OCD have another diagnosis. Pittenger says the most common co-occurring conditions are:
- Anxiety disorders
- Major depressive disorder
- substance abuse
- ADD and tics in children with OCD
OCD can be partially caused by genetics, but there are other causes as well. More research needs to be done to determine exactly what the role of genetics is in OCD as well as how other risk factors contribute to the development of OCD.