- OCD is partially genetic, but researchers have been unable to locate a specific gene associated with OCD.
- Research on twins has estimated that the genetic risk for OCD is around 48% percent, meaning that a half of the cause for OCD is genetic.
- Other risk factors include childhood trauma, differences in brain functioning, the condition PANDAS, and having another mental health illness.
- This article was medically reviewed by Mayra Mendez, Ph.D., LMFT, a licensed 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.
- Visit Insider’s Health Reference library for more advice.
Obsessive-compulsive disorder, or OCD, is a mental health condition that can be mild or debilitating. The condition is characterized by having troubling obsessions or intrusive thoughts as well as compulsions that need to be carried out in order to temporarily soothe the anxiety caused by the distressing obsessions.
Over the years, there has been much discussion surrounding whether or not OCD is genetic and if 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 partially genetic
OCD is partially genetic. “Genetics contribute to overall risk, but they do not completely determine whether or not an individual is going to develop the disorder,” says Christopher Pittenger, PhD, Director of the Yale OCD Research Clinic.
We are a long way off from having a clear understanding of the genetics of OCD, Pittenger says, but there are indirect approaches that researchers have used to learn about the genetics of the disorder.
For example, a 2013 study published in Depression and Anxiety looked at 2,057 pediatric and adolescent OCD patients versus 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 looking at 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, whereas 21% of fraternal twins (who share 50% of DNA) both had OCD. This led researchers to infer that the more DNA is shared between family members, the higher the likelihood that there will be a co-occurrence of OCD. The study determined the heritability (genetic risk) for OCD is around 48% percent, meaning that a half of the cause for OCD is genetic.
Researchers are still working to identify the specific gene(s) associated with OCD. Pittenger says that genome-wide association studies or GWAS, that have been conducted trying to find a gene have been too small to determine whether there is a gene.
“We probably need studies 10 times larger before we can expect to start to find robust genetic ‘hits’. Fortunately, there are two much larger GWAS studies underway,” says Pittenger. This means that in the near future, we might have some more answers regarding an OCD-related gene.
Other risk factors for OCD
Since OCD is only partially genetic, there are other risk factors for developing the condition, however, Pittenger says that like with the genetic aspect, other risk factors are not completely understood, either. Some of these risk factors include:
- Childhood stress and trauma: Pittenger says stress and trauma in childhood can contribute to OCD, however, the exact logistics are not totally known. “My sense is that this is a nonspecific effect – childhood stress and trauma are bad, and they increase the risk of a range of different symptoms/diagnoses,” says Pittenger.
- Differences in brain functioning: According to the National Institute of Mental Health, there may be differences in brain structure and functioning in areas of the brain such as the frontal cortex in people with OCD. However, research regarding this is sparse and more studies must be conducted to draw a conclusion.
- PANDAS (pediatric autoimmune neuropsychiatric disorder associated with streptococcus): PANDAS is a rare disorder that has been linked to OCD. Pittenger says the induced autoimmune process in this disorder may trigger a sudden onset of OCD symptoms. A 2008 study published in Development and Psychopathology confirmed a link between structural and functional brain changes post-PANDAS and OCD, but more research is needed.
- Pregnancy: During pregnancy and in the time after giving birth, there are major changes to the hormones in the body, and this is thought to possibly trigger OCD. The sudden increases in the levels of the hormone oxytocin are thought to be responsible.
- Autism: Autism and OCD seem to be related. A 2015 study published in PLoS One found that those diagnosed with an autism spectrum disorder had a two-fold risk of also developing OCD.
- Having another mental health condition: 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 tic disorders in children with OCD
The Bottom Line
OCD may be partially caused by genetics, but there are other causes as well. More research needs to be conducted to determine exactly what the role is of genetics in OCD as well as how the other risk factors contribute to somebody developing OCD.