No Doubt Autism Is Genetic, But Is the Environment Also Implicated?
My first introduction to autism was Rain Man,” says Bobbie Gallagher of the 1989 movie. “That was all a lot of people knew about autism for a very long time.” Her limited perception of the disorder, which Dustin Hoffman’s K-Mart- and Judge Wapner-obsessed character brought into the public’s consciousness, was about to change drastically. Unfortunately, the same could be said for many of her Brick Township, New Jersey neighbors.
Bobbie’s nine-year-old daughter, Allana, has infantile autism, the most severe form of this developmental brain disorder. “Allana is a handful,” says Bobbie. “She is very limited in her ability to speak. I can’t ask her how her day is—she doesn’t even know I’m asking.” Her eight-year-old son, Austin, is non-verbal. Like the Rain Man’s ability to memorize phone books and count at near-warp speeds, Austin, too, has some savant skills. He prankishly changes the color of all the icons on the family computer to black, and downloads screen savers from mysterious locations.
But Allana and Austin are hardly the newest, or even most challenged, kids on the block. When Bobbie and her husband Billy first started a parents group called POSSE to get special services for their children, they began to realize just how many families in their community struggled with autism. “If I took you on a walk outside I could take you to 12 children with autism in 10 minutes,” says Bobbie. And she’s right.
But does that make Brick the latest cluster in a nation of at-risk communities, or simply indicative of a greater trend? A 1999 report by the California Department of Developmental Services cited a 273 percent increase in the number of people receiving autism services between 1987 and 1998. The report warns, however, that there are also more people living in California now, period.
Changes in number may reflect changes in the definition of autism, and improved recognition of the disorder as well, cautions the Centers for Disease Control (CDC). Once defined by a profound lack of contact and extremely ritualistic behavior, the definition has since broadened to acknowledge a wide range of characteristics, with different manifestations and levels of severity.
According to the National Institute of Mental Health, autism is “a brain disorder that typically affects a person’s ability to communicate, form relationships with others and respond appropriately to the environment,” symptoms that begin to surface only after the first few years of life. Complicated to diagnose, it is identified not by a standardized medical test, but by close observation of communication and developmental levels.
Autism affects all racial, social and ethnic groups, in every region of the world. Up until now, the best guess of the medical community has been that one in 1,000 children is affected by autism, while two to five may exhibit some form of the disorder. Recent studies in Europe and Asia point to numbers closer to two in 1,000. Little is known about the rate in the United States.
The first ongoing surveillance for autism in the U.S. was initiated in 1998 by the CDC in Atlanta, Georgia. About 80 percent complete, early results indicate a rate of two to three autistic children per 1,000. A similar system is being developed for six counties in West Virginia, and another two states will be awarded grants to set up surveillance programs this year.
Connecting the Dots
But perhaps Bobbie’s walk around the neighborhood is more revealing than even these new statistics imply. In response to community concern, CDC evaluated the population in Brick and discovered the incidence of autism there to be much higher than average—in fact, the highest ever recorded. Between the ages of three and 10, four children per 1,000 in Brick were autistic, and 6.7 per 1,000 exhibited a related autistic disorder.
And “nobody notices the problem is actually getting worse,” says Bobbie, because “the report doesn’t show it.” That 6.7 was an average—6.1 per 1,000 children were between the ages of six and 10, while 7.8 were between the ages of three and five.
Four of the families in the Brick study, like the Gallaghers, had multiple children with an autism disorder. That in itself isn’t surprising since “autism is believed to be highly genetic,” says Dr. Eric London, of the National Alliance for Autism Research (NAAR). “However, almost undoubtedly not completely genetic. The prevailing belief,” London says, “is that there is a genetic predisposition to getting it, but likely that some other factor contributes to it. The environment could certainly be one.”
The roots of autism now seem to lie in not one, but a cluster of unstable genes, which under special conditions, may interfere with brain development. Certain cases have followed an environmental trigger, points out Dr. Eric Hollander, clinical director of Seaver Autism Research Center at Mount Sinai School of Medicine. Exposure to thalidomide, for instance, a medication given to women in the 1960s to treat morning sickness, or anti-convulsants like Depakote. There is also evidence that viral infections like rubella may be a risk factor.
One theory to recently stir controversy is that vaccines, the Measles-Mumps-Rubella (MMR) vaccine in particular, may bring on the disorder—a theory that CDC emphasizes there is no evidence to support. A recent study in the United Kingdom turned up no dramatic increase of autism after initial introduction to the vaccine.
Hollander’s work at Mt. Sinai dips into a database of 50,000 live births to examine the relationship between autism and exposure to the labor-inducing drug pitocin. The correlation looks strong, but Hollander cautions that initial results could be misleading—complicated by the demographics of the population, or the effects of other medicines.
As for Brick, because most autistic children are not formally diagnosed with autism until the ages of two or three, it’s difficult to retroactively gather pertinent information on any toxic burden during pregnancy and infancy, says Robert Knowles, environmental scientist with the Agency for Toxic Substances and Disease Registry (ATSDR).
The agency used data supplied by the Brick water authority for the years 1987 through 1995 to evaluate environmental exposure in the community. It concluded that although water levels in wells, the municipal water supply and groundwater below the Brick landfill (a Superfund site) had at some point all contained a variety of hazardous chemicals, the threat was not pervasive enough to be implicated in the unusually high incidence of autism. One of the contaminants, though, trihalomethanes, was detected at levels associated with a two-fold increase in neural tube defects; it has been recently hypothesized that autism may be caused by a disturbance of neural tube closure during gestation.
Although the dynamics are still ambiguous, the fact remains: there are conservatively 400,000 people in the U.S. with an autism disorder; over 20 million have some type of developmental brain disorder
, from learning disabilities to mental retardation. “We know very little about any environmental influences on brain development,” says London. “Environmental scientists have been preoccupied with cancer and a few known toxicants like lead and mercury—but there are literally thousands of compounds out there that could be affecting the brain.”
“If I don’t know where the threat is coming from, how do I know that I’m moving away from it?” asks Bobbie, when deliberating her family’s future in Brick Township. (The ATSDR has already been asked to investigate two other communities.) “I don’t even begin to know where to go. We may just be moving from one cluster to another.” But she wonders just the same what future she’s giving Chelsea, her perfectly healthy 10-year-old daughter, by staying.
JENNIFER BOGO is associate editor of E.