new research suggests.
This finding from a large, register-based study is particularly surprising because results from previous studies of major depression and anxiety disorder have shown a significant effect of parenting and a child’s home environment on the risk for these disorders, the investigators noted.
While the results likely won’t change patient treatment, one expert said it could alleviate concerns of some parents with OCD who fear that witnessing their obsessive behaviors might put their children at higher risk for the disorder.
“The evidence is consistent with the idea that the psychological transmission of OCD from parent to child, if it exists, is really pretty weak,” lead author Kenneth S. Kendler, MD, professor of psychiatry and director of the Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, said in an interview.
The findings were published online in JAMA Psychiatry.
Family analysis
The study is the first to include adoptive parents in an analysis of OCD transmission, which allowed investigators to answer the nature versus nurture question that is often difficult to decipher.
Working with Swedish population registries, researchers identified more than 2.4 million offspring. Of these, 27,141 individuals (1.1%) had a lifetime diagnosis of OCD.
Families were divided into four types: intact families, with kids who lived at home with their biological parents from birth to at least age 15 years; families with kids who never lived with their biological father; families with children who did not live with their biological fathers between birth and age 15 years but who lived with a stepfather for at least 10 of those years; and families with children who were adopted before the age of 5 by people with no biological connection to the child.
After analyzing data from all parent-child relationships, researchers found that genes plus rearing (odds ratio, 3.94; 95% confidence interval, 3.58-4.33) and genes only (OR, 3.34; 95% CI, 2.27-4.93) were significantly more likely to be correlated to transmission of OCD from parent to offspring than rearing alone. Rearing only (OR, 1.4; 95% CI, 0.45-4.39) was not significantly correlated with OCD transmission
“It appears from our data that the only substantial transmission that occurs is in the genes parents transmit, not by the modeling of behavior,” Dr. Kendler said.
“There’s an idea that you can learn some things from your parents from psychopathology, but we didn’t see that kids picked that up much in the case of OCD,” he added.
However, there was one outlier: Children raised by stepparents or adoptive parents with an anxiety disorder had a greater risk of developing OCD.
Given the lack of evidence of a strong rearing effect in other analyses, Dr. Kendler noted that this rogue finding could be caused by an underpowered sample; the researchers plan to study the data further.
“Psychiatric disorders, like many other conditions, are often correlated with neighboring conditions,” he said. “Our study would suggest that some of the molecular genetic variants between OCD and generalized anxiety disorder or other anxiety disorders would be shared, but some would be unique.”