By Jenna Birch
March 17, 2017
Obsessive-compulsive disorder (OCD) can take many forms. Perhaps someone washes her hands over and over again, leading to cuts and skin damage. Or maybe she can’t fall asleep at night until she’s gotten out of bed to make sure the door is locked. Perhaps she always orders objects in a specific, uniform way.
While these behaviors might seem innocuous, they are actually driven by intrusive thoughts and irrational fears that an OCD sufferer can dwell on for hours a day. While the cause of obsessive-compulsive disorder was previously unknown, a new study published in the journal Molecular Psychiatry has finally shed light on a potential source in the brain.
By tinkering with mice models, a team of researchers from Germany found that rodents with a deficiency of the SPRED2 protein engaged in excessive grooming rituals. This protein generally inhibits signals from sliding along a pathway called the Ras/ERK-MAP kinase cascade. Without SPRED2, signal pathways become overactive.
Here’s why that matters in the brain: The SPRED2 protein is normally prevalent in areas like the basal ganglia and amygdala, which are responsible for functions like decision-making, emotional reactions, voluntary motor control, and habitual behaviors. Without that protein inhibitor, the initiator of these pathways (the receptor tyrosine kinase TrkB) runs on overdrive.
A person with OCD may not be able to stop specific thoughts and behaviors, because signals are flying unchecked down the Ras/ERK-MAP kinase cascade pathway in these key regions of the brain. Think of it like a water slide of thoughts you can't turn off or slow down because you're missing the knob that turns off the water — the SPRED2 protein is the knob.
Similar to eating disorders, anxiety, and other mental health issues, obsessive-compulsive disorder is currently treated with various antidepressants — which the team did use to effectively treat the condition in their experiment. However, the scientific community has been searching for that underlying mechanism of OCD, so doctors can use more targeted, and perhaps better, treatment methods.
According to study researcher Kai Schuh, a professor at the Institute of Physiology at the Julius-Maximilians-Universität in Germany, discovering the link between OCD and the Ras/ERK-MAP kinase cascade may be a crucial step.
“Our study delivers a valuable new model that allows the disease mechanisms to be investigated and new therapy options for obsessive-compulsive disorders to be tested,” he told Science Daily.