Researchers Identify Regional Clusters of Autism Cases in California

February 3, 2010

( -- A Columbia study has determined there are certain geographical areas in California where newborns are more likely to develop autism. The findings suggest that autism is a condition determined by one’s local environment, challenging the argument that causal factors exist evenly across the country. The study, which pinpoints a small area near West Hollywood as the center of California autism cases, was published recently in the Health & Place journal.

“Our findings point strongly to the idea that a local rather than a global process is associated with the increased risk of ,” said Peter Bearman, the Jonathan Cole Professor of the Social Sciences and principal investigator of the paper. “Such a local process could be either an environmental factor or a factor or both.”

Autism impairs social interaction and predisposes children to restrictive and repetitive behaviors. Over the past two decades California has witnessed a particularly large spike in autism cases. Between 1992 and 2006, the state’s caseload increased 598 percent.

After analyzing 11,683 autism cases among the 4.1 million babies born in California from 1993 to 2001, the researchers identified a primary “cluster” of autism in the state. Children born in this cluster, roughly 20 by 50 kilometers, were four times more likely to develop autism than children born elsewhere in California. These children were also two times more likely to have autism than those born to mothers over age 40—a factor strongly associated with increased risk of autism.

In addition to the high-risk cluster in West Hollywood, the researchers discovered 38 secondary clusters in the state. Each of the secondary clusters is located within the greater Los Angeles region.

The study does not attempt to identify the cause of autism—a much debated topic—but it suggests that increased prevalence is spurred by local variables, such as or social influences. In the case of West Hollywood, social influences might include increased awareness of autism, decreased stigma associated with the disorder, or increased number of local advocacy groups, said Soumya Mazumdar, a postdoctoral research scholar at Columbia’s Institute for Social and Economic Research and Policy (ISERP) and the study’s first author.

The Columbia team used a statistically rigorous method—Kulldorff’s Spatial Scan Statistic—to demarcate clusters at high risk. The researchers controlled for critical variables, including parental age.

“The findings suggest that we should devote considerable resources to understanding what environmental drivers are operative in autism cases,” said Bearman. “We also need a better understanding of how the diffusion of information operates—how we identify the symptoms of autism, how we secure appropriate diagnoses, and how we treat it.”

More information: Paper online:

Related Stories

Recommended for you

More teens than ever aren't getting enough sleep

October 19, 2017
If you're a young person who can't seem to get enough sleep, you're not alone: A new study led by San Diego State University Professor of Psychology Jean Twenge finds that adolescents today are sleeping fewer hours per night ...

Across Asia, liver cancer is linked to herbal remedies: study

October 18, 2017
Researchers have uncovered widespread evidence of a link between traditional Chinese herbal remedies and liver cancer across Asia, a study said Wednesday.

Eating better throughout adult years improves physical fitness in old age, suggests study

October 18, 2017
People who have a healthier diet throughout their adult lives are more likely to be stronger and fitter in older age than those who don't, according to a new study led by the University of Southampton.

Global calcium consumption appears low, especially in Asia

October 18, 2017
Daily calcium intake among adults appears to vary quite widely around the world in distinct regional patterns, according to a new systematic review of research data ahead of World Osteoporosis Day on Friday, Oct. 20.

New study: Nearly half of US medical care comes from emergency rooms

October 17, 2017
Nearly half of all US medical care is delivered by emergency departments, according to a new study by researchers at the University of Maryland School of Medicine (UMSOM). And in recent years, the percentage of care delivered ...

Experts devise plan to slash unnecessary medical testing

October 17, 2017
Researchers at top hospitals in the U.S. and Canada have developed an ambitious plan to eliminate unnecessary medical testing, with the goal of reducing medical bills while improving patient outcomes, safety and satisfaction.


Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (3) Feb 03, 2010
The same time of the study is when Jim Carrey's career was at its peak.

So that means that Jim Carrey's career is guilty of causing teh autism, right?
3.7 / 5 (3) Feb 03, 2010
The most likely explanation, especially for a condition with contentious diagnostic criteria, is that the geographic disparities are the result of differences in medical practitioners.
not rated yet Feb 04, 2010
It might just be statistical noise... but no harm in checking.
Feb 04, 2010
This comment has been removed by a moderator.
1 / 5 (1) Feb 04, 2010
Why do you link MTBE with the austistic spectrum, Bob B? I say spectrum because there is such a wide range of behavioral phenomena that get lumped under the label of "autism" that there is little evidence that only a single causality will be found.
not rated yet Feb 04, 2010
Only because MTBE is rather new in the populations drinking water. If cases are on the rise, I asked if there might be a link, that is all.

I accept your statement: wide range of behavioral phenomena that get lumped under the label of "autism" that there is little evidence that only a single causality will be found.

On-the-other-hand, as a computer test engineer I know odd things can randomly occur resulting in similar behaviors such as BSOD's or "hangs", etc., so, I was just wondering if inputs to our body can randomly cause issues in our behaviors.
1 / 5 (1) Feb 04, 2010
You present an interesting question, but in the case of autism, it isn't something that goes away when environmental impacts are removed. These are largely, if not entirely, developmental process impairments that are with these people for their entire lives.

Since it is a spectrum of mental and behavioral disorders, some of the patients appear to benefit from different stimuli and medical practices.

To put it in software terms, this would be more like a large structure that should contain low level register information that has a low level random number of random bits changed. No two computers would behave the same. While some of the bits don't affect much, others cause hard crashes at a frustrating rate. The failures wouldn't appear to be the memory, the buses or the processor, but are part of a complex pattern involving every single item across the entire computer, including all of the bits stored in media.
not rated yet Feb 04, 2010
This can be a touchy topic for discussion. For example, I am wondering if there might be a correlation between the concentration of male double Y chromosome and/or female equivalent and autism. Jim Cary proved that attention and behaviour modification contributes a great deal to overcoming autism difficulties, leading to the presumption that environment is an influential factor in determining autism. The presence of a sibling or parent with YY has an effect on the environment in which children are raised. Also, one can generalze that the social focus in West Hollywood is not so much on proper parenting as it is on celebrity and success. Child-rearing is a sensitive affair.
not rated yet Feb 05, 2010
which pinpoints a small area near West Hollywood

Wanna bet that these locations with high incidences of autism also have high incidences of cocaine use amongst adults?

Perhaps those who decry vaccination should stay off the nose candy if they plan on having children.
not rated yet Feb 05, 2010
Interestingly, the symptoms of autism are very similar to those of trauma induced shock.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.