A controversial new study from Denmark shows a link between circumcision and autism, although experts differ sharply over what to make of it.
For the study, published online Jan. 8, 2015 in the Journal of the Royal Society of Medicine, a pair of researchers looked at cases of autism spectrum disorder (ASD) in more than 340,000 boys born in Denmark between 1994 and 2003. The researchers found that the overall risk of developing autism before age 10 was almost 50 percent higher for circumcised boys than uncircumcised boys.
What explains the link?
"All we can say at this point is that there is a statistical association between circumcision and autism," study co-author Dr. Morten Frisch, a consultant at the Statens Serum Institut (State Serum Institute) and adjunct professor of sexual health epidemiology at Aalborg University in Copenhagen, told The Huffington Post in an email. "We cannot say whether it is a causal association or some spurious non-causal link for which we currently don't have an explanation."
Yet Frisch--who is known in Denmark as an outspoken critic of circumcision--raised the possibility of a causal link, with psychological disturbances stemming from the pain of circumcision as a potential culprit. As he and his collaborator wrote in the introduction to their study:
"...painful experiences in neonates have been shown in animal and human studies to be associated with long-term alterations in pain perception, a characteristic often encountered among children with ASD... The present study was carried out to address the hypothesis that ASD might be a rare adverse outcome in boys undergoing ritual circumcision during a vulnerable period in life."
But other experts pooh-poohed that hypothesis.
"One has to be very careful drawing any conclusions from studies like this," Dr. Douglas S. Diekema, a pediatrician at the University of Washington in Seattle and one of the authors of an American Academy of Pediatrics policy statement that is broadly supportive of circumcision, told The Huffington Post in an email. "They raise questions for further study, but do not provide answers... Correlation does not imply or prove causation."
If circumcision really did cause autism, Diekema said, one would expect the rates of autism to have fallen in recent decades along with circumcision rates. "In fact," he said in the email, "we have seen just the opposite."
Nearly 80 percent of boys born in the U.S. in the 1970s and 1980s were circumcised, Live Science reported in 2012, a number that had fallen to 62.5 percent in 1999 and 54.7 percent in 2010.
Meanwhile, data from the federal Centers for Disease Control and Prevention show that autism has become increasingly prevalent. Among children born in the U.S. in 1992, about one in 150 developed autism. Among children born in the U.S. in 2002, about one in 68 developed it.
Diekema said the circumcision-autism link was likely to be spurious but nonetheless urged parents who wish to have their child circumcised to insist that adequate pain control be provided both during and after the procedure.
Frisch too called for additional research but offered different advice.
"For parents, and particularly those whose decisions are not dictated by religion, my advice would be to consider the whole question of circumcision from the child's perspective," he said in the email. "After all, it is his genitals--and who has the right to permanently alter them?"
The academy's circumcision policy statement was issued in 2012. It maintains that the risks of circumcision are outweighed by the benefits, including a reduced risk of contracting sexually transmitted diseases.
Circumcision guidelines issued recently by the CDC mirror the academy's statement.