If you have obsessive-compulsive disorder (OCD), you’ve likely wondered what may have caused it, including whether there is a genetic basis for it. Understanding the answer to this question can shed light on the biology and neurology of OCD, whether it’s preventable, what treatments work, and more.
We spoke with Dr. Jamie Feusner, chief medical officer at NOCD, to hear an expert’s perspective on the relationship between the human genome and OCD. Here’s what we learned.
What does it mean for a condition to be genetic?
To understand what it is for a condition to be genetic, we first need to determine what genes are. Genes are what allow hereditary traits, like hair and eye color, to be transferred from parent to child. They are made up of sequences of DNA and contain the biological instructions that allow for the development, growth, and reproduction of life.
Definition
So what does it mean to say a trait or condition is genetic? According to Dr. Feusner, a condition is genetic “if at least some component of it is caused by genes.”
He further clarifies this statement by highlighting what the definition does not imply.
It doesn’t mean other factors don’t play a role
“There’s almost nothing in terms of what people experience medically that is 100% genetic,” says Dr. Feusner. “Almost always, there are some genes working in combination with environmental factors in a very broad way.” In other words, genes don’t work in a vacuum, and the traits we ultimately acquire result from a complex interaction between genes and external factors, such as our upbringing, exposure to other illnesses, modifications to the genes after one is born, and more.
It doesn’t mean it’s the result of only one gene
“Calling a condition genetic can carry a connotation that it’s the result of a single gene, but this is rarely the case. Many conditions, especially psychiatric ones, are polygenic, which means that in any given person, there may be multiple genes that are contributing,” says Dr. Feusner.
It doesn’t mean the condition is inevitable
Just because a condition is genetic doesn’t mean you’ll automatically develop it if you have the relevant gene or set of genes. As Dr. Feusner states, “it doesn’t mean that everybody who has that gene or set of genes will get it. It just means the probabilities increase if other environmental factors occur.”
Is OCD genetic?
Researchers have demonstrated that there is likely a genetic component to OCD that puts one at greater risk of developing it. To show this, they sought to determine if having a relative with OCD, such as a parent or a sibling, puts one at a greater risk of having it oneself. If so, this would provide evidence that OCD is likely at least partly genetic, because people share a greater percentage of our DNA with relatives than with non-relatives.
The results suggest that genetic factors affect whether one develops OCD. For example, Dr. Feusner notes that “if one of two parents has OCD, then there’s about a 10% chance their child will have it as well, which is much higher than the risk in the general population.”
Twin studies offer even more compelling evidence. In these experiments, scientists look at pairs of identical twins, who share about 100% of their genetic profile, and non-identical twins, who share about 50%, and assess the odds of one twin having OCD if the other does. What they found is that having a twin with OCD significantly increases one’s chances of developing it and that the risk is highest for identical twins, who share almost all their DNA. For example, identical twins generally have about double the risk of having OCD if the other twin has it, compared with non-identical twins.1
What genetic factors might contribute to OCD?
It’s important to note that the genetics of OCD are complex, and scientists are still in the early stages of understanding which genes may predispose people to develop OCD and how. With that said, current evidence suggests that certain genetic factors likely play a role in the development of OCD.
In particular, Dr. Feusner highlights the role of genes involved in the transmission of a neurotransmitter called glutamate. For example, studies have found that variants of the SLC1A1 gene, which encodes a glutamate transporter, may be involved in OCD. However, genes that involve the glutamate system are not the only ones that seem to be involved in OCD.
Some genes are not specific to OCD but are also involved in several other conditions. “There are some sets of genes where if you have them, you are predisposed to developing several different types of psychiatric problems,” says Dr. Feusner. “That may be one of the reasons why, when people have a psychiatric problem like OCD, they often have other mental health conditions too, like depression, anxiety, or substance use problems. This is most apparent when two conditions develop at the same time, which may suggest they share genetic components, though, of course, other factors always play a role.”
What else can contribute to OCD?
As noted above, while genes can make one more disposed to developing OCD, they don’t guarantee that you’ll be diagnosed with it. This is because there are several environmental factors that determine whether one may develop OCD. These include:
- Stress: Stress and trauma can make one more disposed to developing OCD.
- Age: OCD frequently begins in adolescence or early adulthood when one is experiencing major development and life changes.
- Substance use: Studies have shown that some street drugs, such as stimulants, may contribute to OCD.
- Illnesses: OCD is sometimes associated with some illnesses, many of which are more common in childhood, such as Lyme disease or strep throat. This can lead to a sudden onset of OCD symptoms.
Of course, any one of these potential “causes” won’t lead to OCD in most people. They have to occur in the proper context, alongside other factors.
Can I prevent OCD if I’m genetically predisposed to it?
Being genetically predisposed to developing a condition, including OCD, does not mean that one is destined to develop it. In addition, at this point, it is not possible to know for sure if you are genetically at risk for developing OCD.
While there is no reliable way to know if you are genetically predisposed to OCD, if you are concerned about certain subclinical symptoms or tendencies, there are proactive measures you can take to manage such symptoms early. Experts argue that by taking the proper measures at this stage, it may be possible to prevent early obsessive and compulsive tendencies from becoming worse (although this has yet to be tested in a study). For example, these authors argue that this might be achieved bysome emphasize the importance of reducing family accommodation, which is when parents, siblings, or partners comply with the requests of high-risk individuals, like attempts at seeking reassurance about obsessive fears.
If you are concerned about early symptoms of OCD, it is a good idea to consult a licensed mental health professional who has specialty training in treating OCD with exposure and response prevention (ERP) therapy, the gold standard treatment for OCD.
In ERP, people confront their obsessions without engaging in safety behaviors or compulsions in an attempt to alleviate their anxiety. This helps them learn to accept uncertainty and allow distress to fade on its own. By starting ERP early, you can learn to manage your symptoms and prevent OCD from becoming worse.
1Carey, G., & Gottesman, I. I. (1981). Twin and family studies of anxiety, phobic and obsessive disorders. In Klein, D. F., & Rabkin, J. G. (Eds.), Anxiety: New research and changing Concepts (pp. 117–136). New York: Raven Press