Back in November, I wrote about how studying animal behavior can help humans with mental illness, and highlighted an ongoing study of dogs with compulsive behaviors at Tufts University. At the time, they were exploring a genetic link to compulsive behavior and anxiety, and had already found that an Alzheimer’s drug showed promise as a potential OCD treatment.
Last week, the Tufts scientists released their research. They found multiple genetic markers connected to OCD-like behavior in dogs.
So what does that mean for us human OCDers?
First off, it reinforces what psychologists have long suspected and previous studies have hinted at: Genetics play a role in determining who gets OCD.
OCD and anxiety disorders tend to run in families, like many mental illnesses, so this isn’t really all that surprising — especially if you believe OCD is a negative side effect of a positive evolutionary trait gone haywire.
This isn’t the first study to find a genetic link. In 2014, researchers at Johns Hopkins University found one genetic marker in human subjects linked to OCD.
But the canine study at Tufts looked at a few things the human research did not. It asked whether there were genetic reasons one person might have severe OCD while another person’s OCD is more moderate. It also asked whether medication-resistant OCD was influenced by genetic factors.
The research team compared whole genome sequencing of 70 Doberman pinschers to search for inherited factors that exacerbate CCD. Researchers identified two loci on chromosomes that were strongly correlated with severe CCD, as well as a third locus that showed evidence of association.
The locus most strongly associated with severe CCD was found on chromosome 34 – a region containing three serotonin receptor genes.
So yeah. Those of us with severe OCD can probably thank our genes for that.
Another interesting find? Severe canine compulsive disorder was linked to chromosome 11, which is thought to increase the risk of schizophrenia in humans. Research has previously shown that OCDers may have trouble distinguishing between imagination and reality, and that parents with OCD or a prior OCD diagnosis is a risk factor for schizophrenia.
Segue time: I’ve been taking a class on Coursera about canine cognition and emotions. It’s a great class, and I very much recommend it. And one of the things we’ve been learning about is how dogs’ domestication process has made them particularly interesting to evolutionary anthropologists studying human behavior and cognition.
For example, dogs appear to have at least a rudimentary “theory of mind” — the ability to read the emotions of other beings and infer behavior from it. They are better at this, particularly with humans, than even our closest primate relatives. They also do better with other cognitive tasks, such as interpreting gestures.
This may make them an especially useful population for studying mental illness in humans and developing new treatments.
According to the Tufts researchers:
“Genomic research on human neuropsychiatric disorders can be challenging due to the genetic heterogeneity of disease in humans,” says neurologist Edward Ginns, MD, PhD, professor of psychiatry, neurology, pediatrics and clinical pathology, and director, program in medical genetics at the University of Massachusetts Medical School and a co-author on the new study. “Canine compulsive disorder shares behavioral hallmarks, pharmacological responsiveness, and brain structural homology with human OCD, and thus is expected to be an important animal model.”
Interesting stuff. I hope it leads to more useful treatments for OCD in humans.