Incidence of Autism Over Time
Epidemiology * Volume 17, Number 1, January 2006
Letters To The Editor of the NY Times
A dramatic rise of 4-fold or more in the incidence of "diagnosed" autism during the decade from the late 1980s to the late 1990s is well documented in Britain, parts of the United States, and Denmark.
The evidence for this conclusion is reviewed in an article that also provides a credible explanation for this increase.1 Here, we extend the estimates of incidence of diagnosed autism based on the General Practice Research Database (GPRD) to include calendar years through 2004 to determine whether the incidence has continued to increase or has leveled off. Our data source was the UK population-based resource GPRD.2 GPRD computer-recorded diagnoses of autism have been shown to be valid in 80% or more of cases.3,4
Criteria for inclusion in this analysis were very similar to those used in our previous studies on incidence of autism.1 The base population consisted of males age 24 to 59 months who had been registered by a practice by 18 months of age. Cases of autism were required to have a first recorded diagnosis from 24 through 59 months (age 2- 4 years).1 Person-time of follow-up for each child began accumulating at age 24 months and continued until the day before the child
turned 60 months of age. We calculated annual autism incidence rates among children in this 3-year age range for each year from 1992 through 2004. Confidence intervals were calculated using modified Byar's formula.5 Trend analysis was conducted using Poisson regression model.
There were 308 incident cases of autism identified from 1992 to 2004 (440,332 person-years in the base population). We excluded 6 potential cases with evidence of severe organic brain disease before the diagnosis of autism. Before 1996 there was a steady increase in the annual incidence of autism of approximately 20% (incidence rate ratio. 1.17;
95% confidence interval. 1.06 -1.30; Fig. 1). The incidence rate ratio estimates the annual relative increase in autism incidence using the first year of interest as the reference.
After a peak incidence in 1999, the incidence rate remained stable from 2000 through 2004 (0.99; 0.88 -1.10).
Wakefield et al.6 in 1998 published a small series of case reports that suggested a causal connection between measles-mumps-rubella (MMR) vaccine and the risk of autism. This report was followed by Taylor et al.7 in 1999, who reported a progressive increase in the incidence of "diagnosed" autism as high as 33-fold in cohorts of children 0 to 5 years of age born in a region of England during the years 1979 through 1992. Taylor and colleagues concluded that expo sure to MMR vaccine did not explain this dramatic rise.
A series of subsequent results based on the GPRD published in 2001 8 and 2003 1,9 documented that the apparent progressive increase in incidence of diagnosed autism in boys age 2- 4 in the early 1990s continued until 1999.1,9 These articles also provided fully convincing evidence that neither MMR nor indeed any vaccines were responsible for the dramatic rise in diagnosed autism over the course of time.1,8 The results1 provided evidence that the rise in diagnosed autism was the result of a change in criteria for the diagnosis at the clinical level.
In the current study, we have extended our previous findings of an increasing cumulative risk of diagnosed autism of 20% per year in Britain in the 1990 birth cohort to the 1996 birth cohort9 and have found the increase in incidence has indeed leveled off in the years 2000 to 2004 (incidence rate ratio . 0.99). We also note that a major increase in the incidence of diagnosed autism occurred among 2- to 4-year-old boys, from approximately 5/10,000 person-years in 1998 to more than 10/10,000 person-years in 1999 —1 year after the published article of Wake.eld6 that received extremely heavy media attention. This finding provides further credence to the proposition that the diagnosis of autism is influenced by clinical perception and awareness of the symptoms, as well as by the public pressure that characterizes the tendency to make this diagnosis.
Hershel Jick Kathleen J. Beach James A. Kaye Boston Collaborative Drug Surveillance Program Boston University School of Medicine Lexington, Massachusetts
School of Public Health University of Massachusetts Amherst, Massachusetts
1. Jick H, Kaye JA. Epidemiology and possible causes of autism.
Pharmacotherapy. 2003;23: 1524 -1530.
2. GRPD. Full Feature GPRD -The General Prac¬tice Research Database. Available at: www. GPRD.com/home. Accessed October 12, 2005.
3. Black C, Kaye JA, Jick H. The relation of childhood gastrointestinal disorders to autism: a nested case-control study using the UK Gen¬ eral Practice Research Database. BMJ. 2002; 325:419-421.
4. Smeeth L, Cook C, Frombonne E, et al. MMR vaccination and pervasive developmental dis¬orders: a case-control study. Lancet. 2004;364: 963- 968.
5. Rothman KJ, Boice JD Jr. EpidemiologicAnalysisWithaProgrammableCalculator(NIH • Volume 17, Number1 , January 2006 Epidemiology • Volume 17, Number 1,January 2006 LetterstotheEditor Publication 79 -1649). Washington DC: US Government Printing Office; 1979.
6. Wakefield AJ, Murch SH, Anthony A, et al. Ileal-lymphoid-nodular hyperplasia, non-spe-ci.c colitis, and pervasive developmental dis¬ orders in
7. Taylor B, Miller E, Farrington CP, et al. Autism and measles, mumps, and rubella vac¬cine; no epidemiological evidence for a causal association. Lancet. 1999;353:2026 -2029.
8. Kaye JA, Melero-Montes MM, Jick H. Mumps, measles, and rubella vaccine and the incidence of autism recorded by general prac¬ titioners: a time trend analysis. BMJ. 2001; 322:460-463.
9. Jick H, Kaye JA, Black C. Changes in risk of autism in the U.K. for birth cohorts 1990- 1998. Epidemiology. 2003;14:630-632..
Aussie Aspie Jailed For Gun Imports, Ecstasy
By Lauren Ahwan http://tinyurl.com/9ftpf
An Adelaide father-of-three who illegally imported enough firearms parts to make two automatic machine guns and possessed more than 900g of ecstasy, has been jailed for seven years.
David Neil Modra, 39, spent about $1370 buying gun parts - that were valued at $28,000 - from the United States over the internet.
Frequently, Modra, who did not even hold a firearms licence, asked the senders to label the items as machine parts or sports goods to avoid detection by customs officers.
However, suspicions were eventually raised and officers searched Modra's Willunga home, south of Adelaide, in 2003, where they also uncovered the drugs.
Modra had more than 500 ecstasy tablets stuffed in plastic bags in a satchel and enough powder to make a further 8784 tablets.
The South Australian District Court, after earlier accepting Modra's guilty pleas to a string of firearms and drug offences, today said the drugs had a street value of up to $450,000.
Judge David Smith said Modra, who had an honours
Why Won’t Feds Regulate Mercury?
By Carolyn Raffensperger for Science For Lawyers
The link between mercury poisoning, eating fish, and brain damage came to the attention of many in the west through W. Eugene Smith’s elegiac photos of Japanese children lying twisted, gnarled, and blind in their mothers’ arms. Japan’s Minamata Bay had been terribly contaminated with mercury from an acetaldehyde plant. Mothers ate mercury-laden fish and passed on the toxic metal to their vulnerable babies. Victims numbered in the thousands. But the authorities did not recognize that pollution caused the terrible damage until 1968, years after the tragedy started, largely because the company hid the research of courageous scientists.
Like most enormous toxic tragedies — Bhopal, asbestosis, or Love Canal — Minamata took a long time to wend its way through the courts. There have been many suits against Chisso, the company, but last year the Japanese Supreme Court also held the state responsible for the spread of Minamata disease after January 1960.
The ruling was unique in establishing government responsibility for some of the damage. Presiding Justice
Chemist Says Mercury Linked To Autism Spike
By Rob Zaleski http://tinyurl.com/a7kae
His detractors call him an alarmist.
"They hate me," Mike Wagnitz acknowledged in an interview this week.
But if that's what it takes to get people's attention, hey, call him an alarmist or anything else you want, Wagnitz said with a laugh.
A senior state chemist, Wagnitz is making health experts uneasy because of his public statements urging people to think twice before getting a flu shot this season. He thinks the shots are especially risky for pregnant women and young kids.
Why? Because about 95 percent of the doses being distributed this winter contain thimerosal, the mercury-based preservative that Wagnitz and others believe is responsible for the startling increase in autism cases in the United States since the early 1990s.
The federal government says that's hokum, noting that despite years of study there's no scientific evidence that mercury in vaccines causes autism. However, as a precaution, the U.S. Public Health Service in the late 1990s asked manufacturers to start phasing thimerosal out of childhood vaccines.
In fact, both the American Academy of Pediatrics and
School Big's 'Seizure' Rap
By David Andreatt for the NY Post
The superintendent of citywide special-education services will be reprimanded for directing subordinates to ignore subpoenas to testify about the future schooling of an autistic boy who suffered a classroom seizure, education officials said.
Susan Erber, the superintendent of District 75, ordered two of her underlings to defy repeated demands of a Department of Education hearing officer for them to speak about placing the boy in a school potentially better suited to his needs.
The directive came to light last month when a department representative testified it was Erber's "policy" not to allow witnesses to appear in person at a hearing,
How Asperger's Feels
By Kate Goldfield
When I was a freshman in college, someone asked a friend of mine if I was autistic. Having almost no knowledge about what autism was other than a dim memory of a "Rain Man"-like character rocking in the corner and nonverbal, I was appalled. How could anyone possibly think I was like that?
Two years later, I rediscovered the subject of autism after seeing a Lifetime movie about it. I was intrigued by some of the concepts in it and began reading everything I could find about autism, purely out of intellectual interest.
I awakened to the notion that a lot of what I was reading sounded like me. I learned that autism is actually a spectrum disorder, which means that there are people who are affected by it on different levels. I discovered something called Asperger's Syndrome, which is high-functioning autism and markedly different in its presentation from what we could call classic autism.
People with Asperger's Syndrome, or AS, I learned, have trouble reading social cues and understanding say in conversations, when to start speaking and when to stop speaking.
Don't Want Toxins In Food?
Then Eating Could Be Tricky
By Sarah Solovitch for The Times.
Toxicologists are quick to point out that raw, natural foods — just like processed ones — are themselves complex chemical mixtures. Start analyzing them and you'll find tens of thousands of chemical compounds, not all of them good for you.
"What protects us is that these chemicals are present at very, very low levels, and we have defense mechanisms in place," says Michael Pariza, a food toxicologist and microbiologist at the University of Wisconsin.
The best-known research in the field comes out of UC Berkeley, where Lois Swirsky Gold has been studying naturally occurring pesticides and synthetic chemicals in foods for the last 25 years.
She points out that hundreds of plant chemicals have been found to cause cancer in rats or mice when given in extremely high doses.
"A healthy diet contains rodent carcinogens galore," says Gold, director of the Carcinogenic Potency Project at Berkeley. "Ninety-nine percent of the chemicals that people take in are natural."
Burton Speaks to Congress
Congressman Dan Burton [R-IN-05] rises in opposition to the vaccine-liability provision in the Department of Defense Appropriations Bill
Public Service Announcement to the Reader:
AUTISM IS TREATABLE.
Consult these sources:
Autism Research Institute
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