Around 2.2 million people in the US are affected by obsessive-compulsive disorder. It is unknown as to what causes the disorder, but researchers from Johns Hopkins University School of Medicine in Baltimore, MD, say they have uncovered a genetic marker that may provide clues.
Obsessive-compulsive disorder (OCD) is a psychiatric condition. It is characterized by intrusive and unwanted anxiety-causing thoughts that trigger repetitive and ritualistic behaviors in an attempt to overcome such thoughts.
For example, a person may have a constant, irrational worry about germs or contamination; therefore they feel the need to repeatedly wash their hands - sometimes for hours at a time.
Mild forms of OCD can add up to an hour a day to a person's routine, while more severe forms of the condition can disable a person so much that they are unable to leave their home.
There is no cure for OCD, but symptoms can be managed through behavioral therapy and antidepressants, such as selective serotonin reuptake inhibitors (SSRIs). However, it is estimated that such treatment only works in 60-70% of cases.
But the Johns Hopkins researchers say their latest findings, recently published in the journal Molecular Psychiatry, may lead to a better understanding of the condition and new therapies.
OCD patients 'have an association near PTPRD gene'
For the study, led by Dr. Gerald Nestadt, a professor of psychiatry and behavioral sciences at Johns Hopkins, the team analyzed the genomes of 1,406 people with OCD, more than 1,000 close relatives of people with the condition, as well as individuals from the general public. In total, the genomes of 5,061 individuals were scanned.
Researchers say the discovery of a genetic marker in people with OCD could lead to a better understanding and treatment for the condition.
From this, the researchers found that patients with OCD had a "significant association" on chromosome 9 near a gene called protein tyrosine phosphokinase (PTPRD).
This discovery of this genetic marker is of great importance, according to the researchers. They note that in animal studies, the PTPRD gene has been associated with learning and memory - areas that are influenced by OCD in humans.
The team says that the gene has also been associated with some cases of attention deficit hyperactivity disorder (ADHD) - a condition that has similar symptoms to OCD. In addition, the PTPRD gene cooperates with another gene family called SLITRK, which has been linked to OCD in animals.
Commenting on the team's findings, Dr. Nestadt says:
"OCD research has lagged behind other psychiatric disorders in terms of genetics. We hope this interesting finding brings us closer to making better sense of it and helps us find ways to treat it."
Earlier this year, Medical News Today reported on a study suggesting that dogs could serve as a model of OCD in humans.
The researchers of this study found four genes consistently linked to OCD in dog breeds susceptible to the disease, such as Doberman pinschers and bull terriers.
Elinor Karlsson, a senior author of this paper, says that finding genetic variants that cause OCD in dogs may lead to a better understanding of the neural pathways involved in the disease.
"Therapies and drugs used to treat OCD today often don't work very well in dogs or in humans," she adds. "If we can figure out precisely which brain circuits are disrupted in OCD patients, this could lead to more effective and targeted treatments."
In 2013, researchers from the Massachusetts Institute of Technology revealed how they were able to block OCD behavior in mice by activating a brain circuit that controls compulsive behavior.