Here’s another reason to love a dog: our best friend is helping scientists identify the genetic variations that may lead to obsessive-compulsive disorder (OCD) in people, according to new research. Because the human and canine versions are often similar — dogs may lick their paws to the point of injury while people may wash their hands until they bleed — the hope is these and other findings will help researchers develop new medications to treat the debilitating disorder.
Certain dog breeds, including German shepherds, Doberman pinschers, bull terriers and Shetland sheepdogs, are prone to high rates of OCD. Scientists suspected that some of the same genetic mechanisms might underlie compulsions in people, such as repetitive behaviors or intense stress when objects aren't in the right order.
Researchers from the Broad Institute in Massachusetts and Uppsala University in Sweden pinpointed four genes with variants, or changes, that were present in dogs with OCD, but not in a comparison group of greyhounds and Leonbergers or “Lion Dogs,” neither of which have high rates of canine OCD. The four genes are involved in forming and regulating synapses, which are simply connections between brain cells that allow them to transmit information.
When thousands or millions of cells are connected this way they form a brain circuit, explains co-senior author Elinor Karlsson, Ph.D., a postdoctoral fellow at the Broad Institute and at the Center for Systems Biology at Harvard University. Scientists hypothesized that in dogs with OCD, and perhaps humans with OCD, the circuit that tells us when a task is complete, for example, is somehow broken.
“Basically, maybe there’s no message being sent that says a task is completed, it’s time to stop,” she explains.
Human OCD is of course much more complex than canine OCD, but the canine genes could nevertheless shed light on what has gone wrong in the human brain.
"Dogs have a simpler genetic architecture, and that simpler architecture gives us a lot of really important clues about human OCD,” explains co-first author Hyun Ji, Ph.D., also a postdoctoral fellow at the Broad Institute.
OCD affects about one in 100 adults and at least one in 200 children and teens, according to the International OCD Foundation in Boston, MA. Depending on severity, treatment can involve a combination of counseling, cognitive behavioral therapy, and medications, such as anti-depressants.
“The right treatment is effective, but there are barriers to treatment such as stigma and misdiagnosis,” says executive director, Jeff Szymanski, Ph.D. the Foundation’s executive director. There is also a lot of misunderstanding. “I’m extremely organized, so I keep my desk neat because I want to, but a person with OCD has intense anxiety, time-consuming and embarrassing compulsive behaviors that they know are irrational and don’t want to do, but can’t stop.”
Animal lovers will be relieved to know that dogs with OCD respond well to the canine version of OCD treatment, such as medication and behavior modification.
“Dogs are a really powerful model for us, and eventually the hope is to help both dogs and humans with OCD,” says Karlsson. “We owe a big debt of gratitude to the dogs and their humans who send in the DNA.”
The new research is soon to be published in the online journal Genome Biology.