What is science telling us about autism?
Few medical disorders engender as much controversy as autism, or as it is now known, autism spectrum disorder or ASD.
The term describes a range of behaviors. But what all people with ASD share is difficulty in social interaction, problems with verbal and nonverbal communication, and repetitive behaviors or narrow obsessive interests. The “hallmark,” according to the National Institutes of Health, is impaired social interaction. About 75 percent of autistics are mentally retarded (“low functioning”). But the spectrum is broad, and includes people like Ari Ne’eman; the scientist Temple Grandin; British mathematician Richard Borcherds (“high functioning”), and the actress Daryl Hannah, who was diagnosed as borderline autistic as a child. The spectrum also includes children so violent, deranged and uncontrollable they have to be institutionalized.
According to most studies, the number of children diagnosed with autism has exploded in the last 30 years, perhaps by a factor of ten, to four to six children per 1,000. Autism advocates call it an “epidemic,” but that is not necessarily so, largely because the definition of autism has been expanded. Children who were not considered autistic before now fall under that rubric, which has expanded the numbers.
For instance, when autism was first described by Leo Kanner of Johns Hopkins in 1943, about two thirds of children we now consider autistic would not have fit into his definition. Since then, the definition has been modified at least four times, each time adding children that would not have been included previously. That explains much, but not all, of the increase in diagnosis.
Increased awareness also plays a role. Pediatricians and therapists believe they now can clearly identify ASD in children, although misdiagnoses—as happened to Ari Ne’eman in high school—once were common. Parents are likely the first to notice something odd about their child and pediatricians can now spot a problem. Is the child not learning language normally? Does the child avoid eye contact? Is the child obsessive about minor things? Unusually inflexible?
A series of tests has been developed to pin down the diagnosis, all based on observation. One test, developed in England by Simon Baron-Cohen, is the standard for picking up signs as early as 18 months of age.
There are no chemical or biological tests at present, although many scientists are researching them, often using animal models. Scientists in Philadelphia, examining autistic children with magnetoencephalography, found that their brains respond a fraction of a second more slowly than those of healthy children to vowel sounds and tones. That is just one test with a small number of children but is the kind that might well lead to a clinical diagnosis.
BATTLEGROUNDS ABOUND
The hunt for the cause of autism also is wrought with contention. Despite the passion and volume of the discussion, scientists now agree on the general cause, even if they don’t know the complete etiology. They certainly agree on what does not cause the disorder: In 1967, the famed psychoanalyst Bruno Bettelheim blamed “refrigerator mothers” and cold parenting for autism. That theory has been discredited.
The hypothesis now generating the most heated debate is that childhood vaccinations cause autism. Yet it is a controversy that seems to exist largely in the minds of parents who are wedded to the vaccine theory, and some newspaper writers.
The science about that hypothesis is unambiguous. An Advanced Google Scholar search of the scientific literature shows more than 800 scientific papers on the origin of autism since 2000, virtually none of which demonstrate a link between childhood vaccination and autism. And Sanjay Gupta—the physician and CNN medical reporter recently nominated for the post of Surgeon General by President Barack Obama, used PubMed, the medical data research tool, to find 404 papers that specifically rejected the vaccine argument. The Institute of Medicine at the National Academy of Sciences and the American Academy of Pediatrics also agree vaccines are not the cause of the syndrome.
This rejection has not diminished the fervor of some parents of autistic children who charge a vast conspiracy by the scientific establishment. Nonetheless, there is no scientific evidence that vaccinations are in any way responsible—and much solid evidence they are not. Autism begins well before children receive standard vaccinations.
The scientific consensus is that genetics is responsible for 90 percent of autism cases (not including Asperger’s, which may in fact be an entirely different disorder). Some researchers have even narrowed the location of the mutations involved on chromosome 11. That’s the good news. The bad news is that there are 160 genes in that chromosome, and since autism is highly unlikely to be caused by a mutation to a single gene, the mechanics are not close to being worked out. At least 10 genes are likely involved. (The cause of Asperger’s is still unknown.)
The evidence for a genetic factor is compelling. If one child in a family has autism, the odds of a sibling also having autism increases by two to eight percent, much higher than expected in the general population but not as great as if only one gene were involved. Identical twins are superb test platforms for studying genetics, and that is true of ASD as well. If one identical twin has classical autism, the odds are 60 percent that the other twin will as well. And if the other twin does not have autism he or she is likely to have learning or social disorders. Not so in fraternal twins. Boys are three to four times more likely to have ASD as girls.
One Yale study – of a small sample – found that the placentas of children later diagnosed with ASD were abnormal. The growth pattern of the cells was different from the placentas of children who never developed ASD. If so, that would further the belief that ASD was planted on conception, not after birth. That also could lead to prenatal testing for autism, raising exactly the moral issue that Ari Ne’eman finds so frightening.
THE CONUNDRUM OF CURE
There is no “cure” for autism, and because, as most experts believe, every case is unique, there is not likely to be one cure. There are treatments and about the only thing everyone agrees on is that the earlier such treatment begins, the better. The Internet and mass media are full of stories about miraculous treatments, often involving animals, usually horses or dolphins. The non-verbal relationship between the child and the animal is believed to ameliorate the symptoms. There is anecdotal evidence behind some of them, but the plural of anecdote is not data.
Generally accepted treatments fall into two categories: education and behavioral interventions, and medications. The behavioral approach involves highly structured and very intensive training sessions to help the child develop communication and social skills. Medications include antidepressants to counter anxiety, depression or obsessive-compulsive behavior. In extreme cases, anti-psychotics and anti-seizure drugs also are prescribed. Occasionally, stimulants like Ritalin help when attention deficit disorder is involved. There is no scientific evidence to support anything else.
Joel Shurkin is a Baltimore-based freelance writer and the author of nine books, mostly on the history of science and medicine and on human intelligence. He was science editor of the Philadelphia Inquirer and part of the team that won a Pulitzer Prize for covering Three Mile Island. He has taught journalism at Stanford University, the University of California, Santa Cruz, the University of Alaska Fairbanks, and is currently an adjunct at Towson University.
Tags: Winter 2009
