Photograph courtesy of IU Department of Psychiatry
Dr. Christopher McDougle chair of the IU School of Medicine's Department of Psychiatry, says no one can say what causes autism. Toxic chemicals, infectious agents and other "environmental hits" are among the factors believed to interact with genetic predispositions to cause the behavioral disorder.
From what I have learned about the connection between autism and the environment these past many weeks, Dr. Christopher McDougle is the man in Indiana for questions like: How is environment defined when experts say they believe genetic predispositions for Autism Spectrum Disorders (ASDs) are triggered by environmental factors?
When I asked professionals working for children’s environmental health in the Hoosier state to recommend sources, McDougle topped their list. His resume includes: 1986 graduate of the IU School of Medicine and a child psychiatry fellowship at the Yale Child Study Center, one of world’s leading research centers on autism.
Another global leader is the treatment center McDougle started at IU’s Department of Psychiatry, where he returned in 1997, after seven years on the faculty at Yale, to head the child and adolescent psychiatry section. He was promoted to department chair three years later.
“We now have the largest autism clinic in America,” he said of the Christian Sarkine Autism Treatment Center, which is located in the Riley Hospital for Children in Indianapolis.
ASDs include Autistic Disorder, Asperger’s Disorder and Pervasive Developmental Disorder-Not Otherwise Specified. They are characterized by lifelong developmental deficits in social, behavioral and communication skills.
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McDougle uses the phrase “gene-environment interaction” to describe the theory of “a genetic vulnerability and then an environmental hit” as their cause.
Sporting a white lab coat and dark blue bow tie with faint, dark green plaid, McDougle said environment means more than industrial chemicals in the context of autism and other psychiatric disorders. Environmental hits, especially “infectious agents,” have been suspected from the earliest days of autism research.
"Due to the fact that autistic symptoms appear between the ages of 1 and 1½, autism researchers have historically focused on prenatal and perinatal causes."
Due to the fact that autistic symptoms appear between the ages of 1 and 1½, autism researchers have historically focused on prenatal and perinatal causes, he said.
Prenatal suspects include fetal damage from medications, abnormal brain development from genetic causes, or infections, he said. Contributing factors at birth could be prematurity, lack of oxygen to the brain, prolonged labor, or infections. Shortly after birth: environmental contributions, or infections.
“Those are the things that you would look at because you know that the cause occurred somewhere between conception and the emergence of the symptoms,” McDougle said.
But studies that have addressed birth trauma have not found anything consistent, he said. “The majority of kids have completely normal birth histories.”
And while studies of identical twins have shown strong genetic correlations, even those haven’t been definitive. Much of the work on genetics and autism has looked at “classical neurotransmitters -- serotonin, norepinephrine, dopamine,” McDougle said. But while positive findings have been found in some large samples, other studies have been contradictory.
“There’s been nothing that’s held up consistently over time, which has been frustrating,” he said. “It mirrors the complexity of the clinical presentation.”
Whether autism existed before 1943 will never be known, McDougle said, but that’s when the behavioral disorder first appeared in the scientific literature. And assuming for the sake of argument it didn’t, one change that was happening at that time was the widespread use of antibiotic drugs. Penicillin was first manufactured and sold as a drug in 1942. Streptomycin was discovered a year later.
"Studies that have addressed birth trauma have not found anything consistent."
A 1960s epidemic of rubella, a.k.a. German measles, and an apparent increase of autism in affected children focused attention for a while on viral infections, he said.
And some have gone so far as to speculate that more children develop autism who are born at times of the year when they are more vulnerable to infections. “That’s really been controversial,” McDougle said, “and a number of studies have not found that.”
The truth is, regardless of the theory, no one can say what causes autism, he said. “Honestly, if someone was going to give a talk on the etiology or causes of autism, it would be entirely speculative. There’s nothing that’s known.”
McDougle was born in Baltimore, but his family moved when he was an infant to Fort Wayne, where he was raised. After earning a degree in chemistry from Valparaiso University, he enrolled in the IU medical school, intent on becoming a psychiatrist. One summer spent at an inpatient psychiatric unit in Fort Wayne cemented his career path.
“I was struck by the relative lack of understanding of cause and etiology of the profound disorders,” he said. “That’s what I wanted to do heading into med school, and I never wavered tremendously from that.”
"The truth is, regardless of the theory, no one can say what causes autism."
In addition to autism, McDougle also focuses on obsessive-compulsive disorder and Tourette’s Disorder. His specialty is psychopharmacology.
One autism theory that has driven his research involves the autoimmune system. Although no data exists to support the contention, McDougle said it wouldn’t surprise him if autoimmune disorders allow the mother’s body to attack itself during fetal brain development.
“In some ways, a baby inside a mother is a foreign body,” he said. And in someone with a genetic vulnerability to autoimmune disorders, that might trigger some kinds of reaction during brain development.
“There are hints in the literature that there may be something going on there,” he said, noting that it’s something he has picked up on in his clinical work, as well. “We want to pursue that more rigorously, because it makes some sense to us clinically and logically.”
While McDougle includes toxic chemicals among the possible environmental triggers for autism, he said it is not a vein of inquiry that he has pursued. “I’m not an expert in toxic exposure to any degree at all,” he said.
Nor are most of his colleagues in the autism community. “There hasn’t been a lot of work in that area by autism researchers per se,” he said. “So we’ve been slow to adopt that, not because we discount it, I think we’ve been busy looking at other things that we’re more familiar with.”
Researchers are studying toxic exposures as possible causes of Alzheimer’s, along with infectious agents and inflammatory-type responses, he said.
“Autism certainly should be looked at in that way,” he said, adding that his autoimmune theory may be related. Some science has suggested toxic exposures can trigger autoimmune disorders.
“The idea of individual vulnerability is something that makes sense to me,” he said, “probably some kind of genetic vulnerability to an environmental interaction. Whether that’s toxic exposure to chemicals, it’s possible.”
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