Blaming Older Fathers for the "Autism Surge" Is Off the Mark
Mainstream media articles on autism science can be frustrating. In the race to woo eyeballs, writers too often spin research findings -- because readers who gasp at, then forward the post generate more page views than those who than try to understand what the represented research means. It's even more bothersome when a story with a sensationalistic headline has a caveat-bearing back end, as that's the part trigger-happy Tweeters and Tumblrs and etc. are less likely to read. I'm watching autism science ado happen online right now, as The New York Times' Father’s Age Is Linked to Risk of Autism and Schizophrenia and similar articles mobilize outcries about elderly sperm driving an "autism surge" -- even thought that's not really what the originating Nature article concludes.
It's easy to see how the opening paragraphs of the Nature piece sparked such hoopla:
By starting families in their thirties, forties and beyond, men could be increasing the chances that their children will develop autism, schizophrenia and other diseases often linked to new mutations. “The older we are as fathers, the more likely we will pass on our mutations,” says lead author Kári Stefánsson, chief executive of deCODE Genetics in Reykjavik. “The more mutations we pass on, the more likely that one of them is going to be deleterious.”
Those who freak out, stop reading, and start forwarding miss critical conclusions as to why these findings -- though grounded in legitimate science (unlike vaccine causation theories of autism) -- don't explain rising autism rates the way heritability does:
...Mark Daly, a geneticist at Massachusetts General Hospital in Boston who studies autism, says that increasing paternal age is unlikely to account for all of the rise in autism prevalence. He notes that autism is highly heritable, but that most cases are not caused by a single new mutation — so there must be predisposing factors that are inherited from parents but are distinct from the new mutations occurring in sperm.
It's also important to note a preferred explanation for increased autism rates: as scientist Emily Willingham writes at Discover Magazine's The Crux, autism is not new; we've just become better at identifying autistic people due to refined diagnostic criteria:
...here we are today, with two diagnoses [autism and Asperger's] that didn’t exist 70 years ago (plus a third, even newer one: PDD-NOS) even though the people with the conditions did. The CDC’s new data says that in the United States, 1 in 88 eight-year-olds fits the criteria for one of these three, up from 1 in 110 for its 2006 estimate. Is that change the result of an increase in some dastardly environmental “toxin,” as some argue? Or is it because of diagnostic changes and reassignments, as happened when autism left the schizophrenia umbrella?
I talked with Emily about the older fathers study, and she emphasized the points above -- the science behind older fathers handing down higher percentages of genetic mutations is solid, but any extrapolation pinning those percentages to increased autism rates does not acknowledge additional, more likely explanations. She also expressed irritation over headlines trumpeting an "autism surge" while failing to acknowledge the lack of a similar "surge" in schizophrenia rates.
MaxDavie also urges similar caution in choosing takeaways from "Fathers' Age Responsible for Autism" articles:
The authors want to explain this by saying that the increase in spontaneous mutations could be causing a rise in autism. And such an explanation is consistent with the data, as well as offering a neat way of explaining some of the rise in autism diagnoses.
However, that would be to fall once again into the 'correlation equals causation' trap. Maybe the excess of spontaneous mutations is not causative, but is just a marker of the fact that dads of autistic children tend to be older.
I have two further issues with most articles on this study: targeting genetics and inheritance implies that parents are at fault for causing their children's autism; this focus on causation implies that we want to know autism's cause so we can cure it. Both outlooks stigmatize autism and autistic people like my son.
Yet most readers don't think twice about seeing autism represented in a continuously negative light, because our society and prominent autism organizations condition us to think of autistics as problems rather than people. And our urge is to fix problems, to get to their root and stop them before they become problems, ideally. It's dehumanizing.
It is true that autistic people often need support -- my son needs 1:1 support, all day, every day. This is why I stand behind autism research, especially into understanding makes autistic people tick, so that supports can be better tailored to actual rather than externally-imposed needs. But I resent the perpetual focus on autism cures and causation. There are very few identified causes of autism; the majority of autistic people are here because that's the way the genetic dice rolled. If you choose to be a parent, you need to understand that your child may be autistic. It's time to accept those odds, and your children.
(For the record, Leo was born shortly after his dad turned 31.)
Background concept of a statistics trend photo by Shutterstock.