Is Obsessive Compulsive Disorder Genetic?

The exact causes of obsessive-compulsive disorder (OCD) are not fully understood, but it is clear that genetics play a role. Current evidence suggests that genetic factors interact with environmental variables to affect the risk of a person developing OCD.

With the human genome having finally been mapped out, the search is on for those genes that cause us to develop illnesses, including obsessive-compulsive disorder (OCD). Although it is clear that OCD has a genetic basis, it is not yet clear which genes may be important and under what circumstances.

Genetic Risk for OCD

Before discussing whether there is a genetic basis for OCD, let’s review some basic genetic concepts and how they relate to illness.

Genes act as the body’s blueprint for making different proteins, which are used to manufacture an enormous number of tissues and biochemicals. Interestingly, different people can have different versions of a given gene, which are sometimes called alleles.

While some diseases like cystic fibrosis are thought to be caused by one specific gene, most diseases, including mental illnesses like OCD, are thought to be caused by a combination of many different genes. In these cases, your vulnerability to a given disease depends on the different versions or alleles of the genes you inherited from your parents and in what combination.

How Environmental Factors Affect OCD

However, it is important to realize that the environment strongly influences whether a particular genetic vulnerability can express itself in the form of an illness. For example, a person who is genetically vulnerable to lung cancer may only develop the disease if they smoke cigarettes or are exposed to heavy environmental pollution.

In another instance, a person who is vulnerable to depression may never become depressed if they don't ever encounter a severe enough stressor.

Research with identical twins has found that similarities in symptoms are attributable largely to genetic factors and unique experiences as opposed to shared experiences.

Understanding the Genetics of OCD

Research using identical twins and the relatives of people with OCD suggests that the greatest factor in a person’s risk for developing OCD is genetic, with the remaining risk being determined by the environment. Given this, researchers have been searching for the specific genes that create a risk for developing OCD.

For example, there is some preliminary evidence that having particular versions or alleles of genes controlling the manufacture of certain brain chemicals may reflect some sort of vulnerability to developing OCD. These include:

• Serotonin (a neurochemical that may be important for OCD)
• Brain-derived neurotrophic factor (a chemical that plays a large role in controlling development of the brain)
• Glutamate (another neurochemical in the brain that could be important for OCD)

That said, it is far from clear how these genes influence the development of OCD, and there is plenty of research that still needs to be done.

Genetic Vulnerability Means Little Without Environment

In addition, it is important to keep in mind that these (and other, as of yet undiscovered) genetic vulnerabilities may only be relevant under the right environmental conditions. For example, OCD is associated with prenatal risk factors, such as gaining too much weight while pregnant and difficult labor, as well as life stressors, such as significant emotional or physical abuse.

As such, someone may not develop OCD unless they possess the right genetic vulnerability under the right (or wrong, perhaps) circumstances.

Studies of the genetics of OCD are currently focusing on genetic differences that might explain the different OCD symptom subtypes that exist. Such research could be helpful in developing treatments that are able to target specific symptoms with greater effectiveness than is currently possible.

Keep in Mind

Having a genetic vulnerability for OCD is not a guarantee that you will develop this condition. It takes a combination of genetic and environmental factors to develop OCD. A 2021 review noted that despite considerable research on the genetics of OCD, researchers still do not fully understand how genetics and environmental risk combine to create the range of symptoms and sub-types that exist.

There is no way to prevent obsessive-compulsive disorder, but watching for signs of the disorder and seeking treatment early on can reduce its effect on your life and ability to function.