Scientists Found Underlying Cause of Obsessive-Compulsive Disorder

A multi-disciplinary team from Germany claims that they have found the underlying cause of a disorder characterized by persistent intrusive thoughts being compensated by repetitive ritualized behavior.

Their discovery, described in a paper published in the journal Molecular Psychiatry, showed that the absence of a certain protein found in some regions of the brain could trigger obsessive-compulsive disorder.

"We were able to show in mouse models that the absence of the protein SPRED2 alone can trigger an excessive grooming behavior," said lead author Professor Kai Schuh from the Institute of Physiology at the Julius-Maximilians-Universität (JMU) Würzburg, in a press release.

For the study, the researchers used mice OCD-like behaviors. These mouse models presents excessive grooming that resulted in facial skin lesions. The researchers observed that the mice with OCD-like behavior lack the protein SPRED2, which is found in particularly high concentrations in regions of the brain, namely in the basal ganglia and the amygdala.

The SPRED2 protein inhibits the so-called Ras/ERK-MAP kinase cascade, an important signal pathway of the cell. Due to this, the absence of the protein leads to a more active than usual Ras/ERK-MAP kinase cascade.

"It is primarily the brain-specific initiator of the signal pathway, the receptor tyrosine kinase TrkB, that is excessively active and causes the overshooting reaction of the downstream components", said biologist Dr. Melanie Ullrich, in a statement.

When the researchers administered an inhibitor to attenuate the overactive signal cascade, the symptoms of obsessive-compulsive disorder improves in their mouse models. Additionally, the OCD-behavior in their mice models were able to be treated with antidepressants, similar to the standard therapy for humans.

These findings open up a new therapy options for OCD. Drugs that inhibits the Ras/ERK-MAP kinase cascade are already available and some of them are approved to be used as cancer drugs.

Around two percent of the general population suffers from some kind of OCD at least once in their life. OCD is sometimes treated with antidepressants. However, there are no drugs that were tailored specifically for the treatment of the disorder.