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Autism epidemic

Image:Increase in autism diagnosis.png

The advent of a possible autism epidemic was first suggested in the mid-1990sby a handful of healthcareprofessionals who noticed sharp increases in the numbers being diagnosed and reported to public health agencies. Most authorities remain ambivalent about whether or not the instance of autismis increasing [1][2][3][4], and therefore whether the term "epidemic" is accurate.

The number of childrendiagnosed with autismhas increased significantly in recent years, leading many scientistsand health carepractitioners to question whether extrinsic factors may be at least partially responsible. The causeof any increase in autism incidence is hotly debated. Researchers have speculated that genetic causes, pollution, food additives, childhood vaccinations, or more thorough diagnosisand screening may play roles. Other speculation attributes the trend of increasing diagnoses to a form of collective hysteria. Researchers have long pointed to changes in diagnostic categories in the Diagnostic and Statistical Manual of Mental Disordersas profoundly affecting the numbers diagnosed as autistic, especially changes set out in DSM-III-R [5][6]and DSM-IV.[7].


  • 1 Caveat
  • 2 Scope of autism prevalence
    • 2.1 Australia
    • 2.2 China
    • 2.3 Denmark
    • 2.4 Japan
    • 2.5 Russia
    • 2.6 United Kingdom
    • 2.7 United States
      • 2.7.1 California
        • Granite Bay cluster
        • Silicon Valley cluster
      • 2.7.2 Connecticut
        • Stratford cluster
      • 2.7.3 Hawaii
      • 2.7.4 New Jersey
        • Brick Township cluster
      • 2.7.5 Pennsylvania
        • Amish anomaly
  • 3 Proposed causes
    • 3.1 Better (and worse) diagnostics
    • 3.2 Genetic predisposition
      • 3.2.1 Natural selection
      • 3.2.2 Assortative mating
    • 3.3 Nutritional deficiencies
    • 3.4 Leaky Gut Syndrome and related
    • 3.5 Vaccine theories
      • 3.5.1 Thimerosal containing vaccines
      • 3.5.2 Attenuated (weakened) live vaccines
    • 3.6 Earlier preschool entrance
    • 3.7 Folic acid
  • 4 See also
  • 5 References
  • 6 External links
    • 6.1 Background issues on autism epidemiology
    • 6.2 Attribution to vaccines suggested or alleged
    • 6.3 Attribution to vaccines uncertain or refuted
    • 6.4 Genetic vulnerability and the 'geek syndrome'


The autism rights movementvehemently disputes the concerns of many that autism has reached epidemic proportions, as this implies to some that autism is a disability or disease. Hence the rest of this article is built on a proposition challenged by a portion of the autistic community. Thus, since autism is diagnosed strictly in terms of cognitive function, the rise in such diagnoses, associated with the many conditions comorbid to autism spectrum disorders, does not necessarily represent an epidemic, per se, based on the prevailing diagnostic criteria.

Scope of autism prevalence

While the number of diagnoses related to autism has increased in recent decades, public health organizations and researchers have not yet been able to fully ascertain whether:

  • More incidents of autism are being reported now, as a result of increased awareness of the disorder
  • The diagnosis is being applied more broadly than before, as a result of the changing definition of the disorder
  • The magnitude of the increase warrants urgent and/or drastic measures a full-blown epidemic would call for

Whether the real incidence of autism had been increasing was quite unclear as recently as 1999.[8] Nevertheless, an increasing prevalence of autism diagnoses has sparked concerns, especially among parents. In response to growing employee concerns among high tech workers, for instance, Microsoftbecame the first major US corporation to offer employees insurance coverage for the cost of behavioral trainingfor their autistic children in 2001, due to the high prevalence among the children of its employees. Elsewhere, the rising prevalence of autistic spectrumchildren threatens to bankrupt families, school systems and government agencies around the globe.

Parent advocacy groups, such as Safe Minds, A-CHAMPand Generation Rescue, object to public health agencies' reservations, pointing out that if estimates of the increasing prevalence are true, several of the world's governments are confronted with a catastrophic health crisis with deep humanitarianand economic implications. They are calling for increased research into environmental factors that might cause or contribute to autism, increased research into therapies and possible cures to treat autism, and greater funding of programs to help autistic people learn to live with their disorder.

There is evidence of a large subset of children with regressive autism, where symptoms do not emerge until after one year of age, and feature a consistent set of symptoms associated with dysfunctional, elevated immune responses. Dr. Andrew Wakefieldhas described some of these cases as autistic enterocolitis. "We are calling this epiphenomenon 'NIDS' (Neuro-Immune Dysfunction Syndromes)," says Dr. Michael Goldberg, a pediatrician on the clinical teaching staff at UCLAand president of the NIDS Research Institute.

In the absence of an agreed-upon explanation for the cause of autism, a vocal and growing number of parents, health professionals, politicians and others are demanding further independent study of a possible causal connection between autism and the policy of universal, compulsory vaccination schedules. This demand reflects a highly controversial debate on the risks and benefits of vaccinations, pitting the medical community and public health agencies against a large proportion of parents (in California, one third of parents of children on the spectrum - see 'vaccine theories' below) and a relatively small group of physicians.

Some members of the autism communityhave expressed dismay regarding the use of the term 'epidemic' to describe the increasing prevalence of autism, seeing such phrasing as inflammatory, especially when used by prestigious interests in the field of autism research.


Australiais apparently experiencing a surge in autism spectrum disorders, where a ten-fold rise in diagnoses have been made in the past decade.[9] The AustralianEducation Department reported a 276 percent jump in students with autism spectrum disorder between 2000and 2005. As of 2005, a total of 23,083 Victorianstudents were placed in school disability and language disorder programs, rising 74 per cent from 13,257 students in 2000. An expert from the Royal Children's Hospitalin Sydney, Australiasaid the figures were "a significant underestimate."


In a July, 2005, interview Robert F. Kennedy, Jr.stated that, "six years ago, autism was unknown in China. We started giving them our vaccines in 1999. Today there's 1.8 million cases of autism in China."[10] Shanghai alone has over 10,000 known autistic children.[11] However, this seems to conflict with a 1997 study, in China, about teaching Chinese to autistic children, [12]as well as a 1991 study of a Chinese "calendar savant". [13]


A study from Denmarkwas published in November 2002, attracting substantial attention. The incidence of autism reported in the study appeared lower than the prevalence reported in the US and other countries. In Denmark, an incidence rate of 1 out of 727 (or 738 out of 537,303) was reported, far less than estimates of up to 1 in 86 among primary school children in the United Kingdomand around 1 out of 150 children in the US.

Danish authorities discontinued use of thimerosalin 1992[14], but cite studies showing a continued increase in the incidence of autism as evidence that thimerosal was not a contributing factor. However, according to Kennedy, "before banning thimerosal, Denmark registered only autistics who were hospitalized - one fifth of the afflicted populations. After the withdrawal of thimerosal, Denmark began counting out-patient autistics in its registries. The resulting spike in raw numbers therefore made it appear that autism rates actually increased after the withdrawal of thimerosal."[15]


A study released in early 2005was the first to examine autism trends before and after the 1993withdrawal of MMRfrom the Japanesemarket, inclusive of children who had not had the three-in-one jab. The MMR was withdrawn in Japan in a crisis of confidence after the mumpscomponent was linked to meningitis. The study's authors reported 48 and 86 cases per 10,000 children in two sequential years prior to withdrawal, doubling to 97 and 161 per 10,000 afterwards in two seqeuential years afterwards. [16]

Dr. Wakefield has noted the specific year to year data shows a dip in autism diagnoses after Japanese public confidence fell in the MMR specifically, and vaccinations generally. Wakefield notes autism rates had risen to 85.9 per 10,000 for children born in 1990, but declined to 55.8 per 10,000 for children born in 1991when MMR uptake declined before the MMR vaccine's withdrawal. Autism rates have steadily increased since that time, after the Japanese public began to accept the notion of three separate vaccines and refinements to diagnostic criteria.[17]


In response to a study performed in 1977, Russia banned thimerosalfrom children's vaccines by 1985. Despite this, the Russian autism rate did not change for at least a decade.[18]

United Kingdom

According to Vaccination News, one in eighty-six primary school children in the United Kingdomhas autism, compared with one in 2,200 in 1988.[19] Another estimate of the UK incidence rate came from the National Autistic Society, which estimated autism spectrum disorders in the total population to be one in 110. A 2001review, by the Medical Research Council, yielded an estimate of one in 166 in children under eight.

According to statistics cited by Bernard Rimland, the autism rate in the UK suddenly spiked after the first introduction of the MMR vaccinein 1989, just as it had after the MMR's introduction in the US in the late 1970s.[20]. This is not consistent with evidence published in the British Medical Journal.[21]

Substantial funds (over £3 million) were spent in the UK on a pro-MMR campaign.[22] Concerted efforts have been made by the British government and pharmaceutical industryinterests to negate the widely criticized 1998study, led by Dr. Wakefield, that showed a consistent set of bowel disorders among a dozen autistic children.[23] The study authors also suggested the need for further studies into the apparent link between MMR and autism, although 10 of Wakefield's co-authors retracted the recomendation six years later.

The 2002 Danish epidemiological study was a consideration in the 2004US Institute of Medicine(IOM) Special Committee decision, which concluded an MMR-Autism connection did not exist.

United States

According to a recent 'conservative' estimate, there are approximately 500,000 autistic spectrum cases in he United States, including perhaps as many as 1 in 150 children. "With eighty percent of autistic Americans under the age of 18, the dramatic impact of this crisis will be felt by taxpayers in the coming years when these autistic children become adults," says Anne McElroy Dachel of the National Autism Association.

Autism is the fastest growing population of special needs students in the US, having grown by over 900% between 1992and 2001, according to data from the United States Department of Education. In 1999, the autism incidence rate in the US was generally cited at 4.5 cases per 10,000 live births. By 2005, the US Centers for Disease Control(CDC) estimates one of every 250 babies is born with autism, or 40 cases per 10,000.

The rising enrollments in special educationclasses in the nation's public schoolsystem provides a clear measurement of how wide-spread the prevalence has become. In Ohioin 1992-93, there were only 22 reported cases of autism, but by by 2003-04 there were 5,146; in Illinois, there were five cases in 1992-93, and 6,005 in 2003-04; in Wisconsin, 18 cases of autism in 1992-93 and 3,259 in 2003-04.[24]

As many as 1.5 million Americans may have some form of autism, including milder variants, and the number is rising. Epidemiologistsestimate the number of autistic children in the US could reach 4 million in the next decade.[25]


California is considered to have the best reporting system for autism in the US. According to data released in late 2005 by the California Department of Developmental Services(DDS), new cases - of professionally diagnosed full syndrome DSM IV autism - entering the DDS system indicated a decline, from 734 new cases during the second quarter of 2005 to 678 new cases during the third quarter of 2005, a 7.5% decline in one quarter.

As of August 1993, a total of only 4,911 cases of autism had been logged in DDS's client-management system, a number excluding milder autism spectrum disorders, such as Asperger's syndrome. By April 29, 1999, the DDS reported a State-wide incidence rate of about 15 to 20 per 10,000, triggering alarms about the staggering increase.

The total caseload handled by the state continues to increase at a pace much higher than population growth, but the recent trend points to a decrease in the caseload increase per quarter. The decline has been speculated to coincide with vaccines containing thimerosal being phased out in recent years. It could also indicate that the awareness curve is starting to level off. It has also been pointed out that the caseload does not yet meet the levels found in population studies.

Critics of the vaccine theory point out that if vaccine injurywas the cause of the increase in autism spectrum diagnoses, a sharp decline in new cases should be expected, and eventually a decrease in total caseload. In contrast, if the better diagnostic awareness theory is correct, a gradual decline in new cases should be expected until caseload increase reaches population growth levels.

As of 2005, the DDS reported a total of 28,046 cases, but that the rate of increase peaked in 2002 and has dropped slightly since then. According to data released by DDS in January, 2006, the number of new cases of professionally diagnosed full syndrome autism entering California's developmental services system in 2005 was the smallest since 2001. The DDS year end report documents that, during 2005, California added 2,848 new cases of autism to its system. Not since 2001, when 2,725 new cases were added, has California added fewer new cases of full syndrome autism to its system. Ever since the record year of 2002, there has been a slow, steady decline in the number of new autism cases entering the 37-year old DDS system, even though levels have still not yet reached the 1 in 166 reported by population-based studies.

According to a report by the DDS, Autistic Spectrum Disorders, Changes in the California Caseload: 1999-2002, the rate of children diagnosed with full-syndrome autism in California nearly doubled between 1999 and 2002, from 10,360 to 20,377. The report stated, "(B)etween Dec. 31, 1987, and Dec. 31, 2002, the population of persons with full-syndrome autism has increased by 634 percent."

California's increase in childhood autism was not due to flawed diagnoses, according to a 2002study led by University of California, Davispediatric epidemiologistRobert Byrd. 1,685 newly diagnosed autisticchildren had entered the state's regional center system the previous year, marking a 273 percent increase over an 11-year period from 1988 to 1999. The data again included only children with classic autism, discounting those with PDD-NOS, Asperger's, etc. "The sheer complexity of this phenomenon prevents any clear conclusions," the report stated. "What we do know is that the number of young children coming into the system each year is significantly greater than in the past."

"It's a dramatic report, but what's shocking is that it's not clear what the cause is," said Dr. Thomas Anders, a child psychiatrist and acting director of the M.I.N.D. Instituteat the University of California, Davis. Yet the report statistics were very "conservative", according to Rick Rollens, former secretary of the California State Senateand father of Russell, who has been diagnosed with autism, adding "It does not include people who are not part of the regional system, and it is estimated that (the regional system is) really serving only half the people with developmental disabilities," said Rollens.

Granite Bay cluster

By 1999, in Granite Bay, California, 22 of the 2,930 children enrolled in grades K-6 were autistic.

Silicon Valley cluster

A surge in autism cases in Silicon Valleymay be due to genesmore common in high-tech workers, according to experts cited in a 2002BBCarticle, which indicated one in 150 children in the region had an autistic spectrum disorder.


The number of autistic children educated at public expense in Connecticuthas increased 325 percent since 1996, according to the State Department of Education. Governor M. Jodi Rellincluded a 38 percent increase, to $25.5 million, in the State's budget, for reimbursement to local schools for special education costs.

Stratford cluster

In Stratford, Connecticutthe number of children diagnosed with autism who receive special education services has increased 400 percent since 1996. Although only 20 children currently in the school system have autism, the cost for their education may exceed $750,000.


Rick Rollens, a co-founder of the M.I.N.D. Institute, found an autism cluster in a small, isolated area on the east shore of Oahu, Hawaii, in part consisting of a dozen native Hawaiian children with regressive autism, all suffering from gastrointestinal problems, sleep disorders, glutenand caseindigestion problems, autoimmune problems, yet having no family history of autism or any other developmental disability.[26]

New Jersey

New Jerseyalso has a high number of autistic children. This may be because, like California, New Jersey boasts many scientific research and high technologyindustry enclaves, which dominate the state's economy. A significant portion of the autistic children in New Jersey, intriguingly, were either born in other States or have parents from another State; many more autistic children may have moved to New Jersey from other states specifically because of its well known special education system.

Brick Township cluster

An 'autism cluster' was identified in Brick Township, New Jersey, in 1999. Parents attributed the diagnoses to environmental pollution, but investigators could not confirm the suspicions. The town had about 40 cases among 6,000 children.


Governor Edward G. Rendellhas dedicated $3 million to help Pennsylvaniaenhance efforts to better diagnose and develop treatment procedures for the 74,000 Pennsylvanians diagnosed with autism spectrum disorders.[27]

Amish anomaly

An apparent anomaly among Amishpopulations was reported in 2005. Although a formal study has not yet been conducted, efforts to assess the prevalence of autism in the Amish community turned up only a very few cases. About 22,000 Amish live in Lancaster County, yet only three or four Amish with autism have turned up thus far in an informal survey of Lancaster County, whereas dozens would be expected at the 1-in-166 prevalence in society at large. "You'll find all the other stuff, but we don't find the autism," according to Dr. Frank Noonan, a Lancaster County family doctor, adding "We're right in the heart of Amish country and seeing none."

In June, 2005, William F. Raub, of the Department of Health and Human Services, suggested the possibility of launching studies of the Amish in response reports of a low prevalence of autism in that community.[28]

These preliminary findings have sparked speculation to the effect that, since vaccinations among the Amish are virtually unheard of, the vaccine-autism link is now well established. These findinds, nevertheless, would appear to be consistent with most other prevalence increase theories as well, including genetics, environmental pollution, folic acid, and any number of concocted theories that have to do with recent changing trends in modern lifestyle.

Proposed causes

When autism was first described and reported by Leo Kannerand Hans Aspergerin the early 1940s, nothing was known about what was causing the previously unrecognized syndrome. The increasing numbers have led to many theories.

Better (and worse) diagnostics

When the rising prevalence of autism spectrum disorders sparked research into the trend in the late 1990s, the medical establishment primarily attributed the increase to improved diagnostic screening or changes in the definition of autism. In 1994, the fourth major revision of the Diagnostic and Statistical Manual of Mental Disorders(DSM-IV) was published [29]. It included substantially updated criteria for the diagnosis of autism and autism spectrum disorders.[30] Professional medical associations, including the American Academy of Pediatrics, say that this revision was an important factor in increasing the apparent prevalence of autism. A 2005 study by Mayo Clinicresearchers found that sharp increases in autism diagnoses have followed revisions in DSM criteria and changes in funding for special education programs. [31].

Much of the prevalence increase could be explained through increased awareness and knowledge about autistic disorders in the part of parents and pediatricians. The implications of this view are that children in the past were likely diagnosed as having a different condition, or not diagnosed at all. Several potential misdiagnosis have been cited, such as mental retardation, learning disability[32] and childhood schizophrenia[33]. High functioning autistic children are sometimes misdiagnosed ADHD [34]and it's possible such misdiagnosis were more common in the recent past. Another possible contributing effect is that of giving a diagnosis of Autistm to children who are not primarily autistic, e.g. those with Fragile-X Syndrome(with characteristics that fit the criteria for autism) and even Down's Syndrome(which may be comorbid with autism.) Dr. Fred Volkmar, an autism researcher from Yale has said that "Autism is a kind of fashionable diagnosis" [35].

It has been pointed out that updated diagnostic criteria, more awareness, and so on, would only account for increases in diagnosis of high-functioning autism, and that there's evidence of prevalence increases in so-called classic autism. But this reasoning is not necessarily correct. If criteria on one end of the spectrum has shifted, it is not unreasonable to suppose that it has shifted across the spectrum. Anecdotal accounts suggest that, in the past, diagnosis were not seeked even for late-talking children. It is unlikely that today, in the industrialized world, a late-talking child would be left undiagnosed after entering the school system. A recent rash of late diagnosis and self-diagnosis of Asperger's Syndromein adults (perhaps due in part to the success of the world wide web) supports this observation. Adults currently receiving a diagnosis of Asperger's Syndromecould have been late-talkers as children, in which case a diagnosis of autism would have been more appropriate, had they been diagnosed then.

Genetic predisposition

For more details on this topic, see Heritability of autism.

Hans Asperger noted a striking tendency for the disorder to run in families, sometimes passing directly from father to son. Clues that genes might be central to autism appeared in Leo Kanner's observations about the emotional distance among mothers of autistic children.

The odds of identical twins sharing a diagnosis of autism are about 90 percent. (Studies go from 60% up to 96%, but seem to cluster around 90%). Parents with one autistic child face a risk of 1 in 20 of having a second autistic child. After having two autistic children, the odds of the next child of the same parents being autistic rise to 1 in 3 [36].

Still, it appears that most parents of autistic children are non-autistic, which is probably what leads to contradictory statements by professionals, such as the following:

  • "The current genetic research estimates that no more than 10% of all autistic cases are genetic in origin. Simply put, the remainder 90% of autistic cases is sporadic with a non-genetic etiology," according to Vijendra K. Singh, PhD. a professor of neuroimmunologyat Utah State University.
  • "... autism appears to be largely genetic in origin, and most autistic children inherit the disorder from their parents," according to Michael J. Dougherty, PhD, is in the Department of Biology at Hampden - Sydney College, Virginia.[37]

The results of identical twinstudies vs. those of fraternal twinsand siblings suggest that a single gene variation cannot account for autism. To obtain those results, there would need to be perhaps 3 or 4 gene variations, which are passed down in part from the mother and in part from the father in most cases. Each gene variation, taken separately, would not be that uncommon in the general population. It is the combination of all of them which would be relatively uncommon. This may also be too simplistic and there might be many different sets of genetic variations that account for what we now refer to as "autism". Normally if a child is autistic, the probability that a parent is autistic should be similar to that of a sibling being in the autism spectrum, i.e. around 5% (without taking into account fitness to reproduce).

There is also evidence of a broader autistic phenotype, i.e. while siblings and parents of autistic children may not be autistic themselves, their chances of having symptoms of related conditions such as ADD, OCD, Tourette Syndrome, anxietyand depressionare considerably higher than normal. [38] [39]

Natural selection

High technology enclaves have been noted repeatedly for having relatively high prevalence rates of autism spectrum disorders. People with highly analytical skills and mathematical capabilities, who excel in certain industries, despite lacking basic social skills, are often labeled as geeksor nerds.

There is evidence that autistic individials have a higher proportion of engineers as close family members than the rest of the population.[40]The explanation offered is that persons with a broader autistic phenotypeare driven to professions where human interaction is not as important as working with objects and concepts.

A hypothesis for the increase in prevalence could thus be based on natural selection, as hinted in Wired Magazine's article titled "The Geek Syndrome".[41] With the advent of the information age, there are more and better paying jobs for people with a broader autistic phenotype, which gives these individuals better chances of finding a mate and procreating. Although a plausible explanation for a small fraction of the observed increase in autism prevalence, the number of reported cases increases so rapidly in places like California that variations in certain job sectors cannot explain it fully. Additionally, this hypothesis would suggest there is a much higher prevalence increase in certain locations, certain socio-economic sectors, and among families with high levels of education, which is not supported by the data thus far. The main flaw of this hypothesis is that while autistic children may have a higher proportion of fathers who are engineers, it's still only a small minority among them (13%) that do.

Assortative mating

According to Simon Baron-Cohen, the genetics that contribute to autism might actually result in part from assortative matingof two particular types of parents, with certain systematizing cognitive traits, both contributing genes. Baron-Cohen believes that "it has become easier for systemizers to meet each other, with the advent of international conferences, greater job opportunities and more women working in these fields." [42]

Assortative mating has not been demonstrated in humans, however. The spouses of identical twins tended to find the other twin annoying rather than attractive.[43]

Nutritional deficiencies

Children exhibiting behavioral and learning disorders may do so in part because of diets deficient in vital nutrients needed for their brains to function normally.

In 1998, a small study published in the Lancet found a consistent set of bowel disorders among a dozen autistic children. Although an emphasis was placed by the authors on a possible link to the MMR vaccine, the study also suggested nutritional deficits caused by bowel disorders, perhaps triggered by vaccines, may have contributed to the onset of neurological disorders.

Leaky Gut Syndrome and related

Some children with autism have responded well to dietary intervention such as eliminating gluten(a protein found in most grains) and casein(the protein found in milk) as well as phenyls and food coloring (see Feingold diet). Most data regarding the validity of these interventions have been the subjective observations of parents and caretakers and no scientific study with proper subject elimination has taken place. Possible determining factors regarding the effectiveness of this as a treatment involve coincidence of a combination of asthma, eczema, diharrea and constipation, strange "yeasty" diaper rash, and uncharacteristic eating habits (eating an entire loaf of bread).

Several unproven theories behind the effectiveness of this as a treatment involve damage to the lining of the stomach and/or intestines allowing the proteins to be improperly metabolized as glutomorphine and casomorphine which are both opiates. The damage to the gut lining is theorized to be caused by immunio-abnormalities and possibly the incidence of early oral-antibiotic use combined with a genetic predisposition.

Vaccine theories

The Center for Disease Controlnotes that "Current scientific evidence does not support the hypothesis that measles-mumps-rubella (MMR) vaccine, or any combination of vaccines, causes the development of autism, including regressive forms of autism."[44] Nevertheless, claims that childhood vaccinations contribute to autism are relatively popular among parents. Bernard Rimlandwas among the first to make the allegation in the early 1990s;[45]before that, the 1985book DPT: A Shot in the Dark, by Harris Coulter & Barbara Loe Fisher, made the allegation. Parents have increasingly disputed the position of the medical establisment, which adamantly rejects vaccine theories because of the repeated studies showing no link. In 2002, the M.I.N.D. Institute indicated one third of parents of recently diagnosed kids blamed vaccines, in comparison to 18 percent of parents whose kids were diagnosed earlier who blamed vaccines. Nevertheless, because of the overwhelming scientific evidence against the vaccine theories, only a very few healthcare professionals accept the possibility that such theories might be true. "Scientists and public health officials say they are alarmed by the surge of attention to an idea without scientific merit. The anti-thimerosal campaign, they say, is causing some parents to stay away from vaccines, placing their children at risk for illnesses like measles and polio."[46]

Vaccines, in particular the MMR, have been accused of involvement in a number of disorders, besides autism, including neurological damage, immune system dysfunction, severe allergicreactions, seizures, Guillain-Barre Syndrome, boweldisorders, blooddisorders and diabetes.[47] However, the Center for Disease Controlnotes that "The available scientific data show that simultaneous vaccination with multiple vaccines has no adverse effect on the normal childhood immune system."[48]

Critics contend that the vaccine-related scare in the US and UK has been promoted by trial lawyers hoping to sue vaccine companies.[49]

Thimerosal containing vaccines

Exposure to mercury, used as a preservative in thimerosalcontaining vaccines (TCVs), leads to neurologic effects that may be the primary cause of the apparent autism epidemic, according to Bernard Rimland, Mark Geier, and a number of advocacy groups including Safe Minds. If true, one would expect the incidence of autism to be declining as the use of thimerosal containing vaccines declines. In the US, removal of thimerosal from children's vaccines was recommended in 1998. Childhood exposure may not have peaked until 2003 in the US, as pharmaceutical companies have moved toward compliance, according to research reported by Mark Geier. That research contradicts the findings of the Food and Drug Administration, which found that all major vaccines (except one influenza vaccine) was thimerosal-free by 2001.[50]And European countries that abolished thimerosal before the US have not had declines in autism. Geier's study was heavily criticized by the American Academy of Pediatrics as unscientific.[51]

The Center for Disease Controlrejects the thimerosal hypothesis as unsupported by scientific evidence: "There is no evidence of harm caused by the minute doses of thimerosal in vaccines, except for minor effects like swelling and redness at the injection site due to sensitivity to thimerosal."[52] In a 2004 report, the Institute of Medicineconcluded that there is no association between autism and vaccines that contain thimerosal as a preservative.[53]

Attenuated (weakened) live vaccines

A number of other organ systems affected by vaccines may also be involved, including gastrointestinal, respiratory, hepatic, immune, dermal, and renal. Andrew Wakefieldhas been at the center of controversies which escalated after the UK National Health Service'sdecision to withhold single-jab vaccines in favor of live virus triple-jab MMR vaccinations. However, Dr. Edward Campion, senior deputy editor of the New England Journal of Medicine, concluded from the 2002 Danish report that "This careful and convincing study shows that there is no association between autism and MMR vaccination."

Earlier preschool entrance

There is evidence that children are entering preschool earlier than in the past, at least in the industrialized world; a trend fueled mostly by the early educationmovement. Following a reasoning along the lines of the 'increased awareness' theory, earlier preschool entrance could in part explain a rise in diagnosed cases of autism for the following reasons:

  • Preschool provides an environment where a toddler's behavior can be compared to that of their peers for extended periods of time. At the age of 2 or 3 autistic children start to show marked behavioral differences and a portion of these children may have otherwise gone undiagnosed after they develop certain skills some time later.
  • Teachers can alert parents based on their past experience with other children.

But earlier preschool entrance could be having an effect that goes beyond increased awareness. It is believed that preschool can be stressful to young children, particularly when they first enter.

Autistic individuals are known to be prone to stress. Stress and social pressure in some autistic children can trigger 'shutdowns'.[54][55]. Stress has also been associated with seizures, and seizures in autistic children have been associated with 'regression'.[56] A plausible conclusion from this is that increased early stress could be amplifying the observed autistic traits of some children.

There is also a belief that stress can cause regressions in the development of non-autistic children in general.[57]. Some parents report observing developmental regressions that they attribute to early preschool entrance.[58][59]

Autistic author Jasmine O'Neillhas said that school is the "end of bliss" for autistic children. Anecdotal accounts of this nature have been used to make dubious links between other types of occurrences in a child's life and 'regression'.

There are two studies that claim extended time in preschool can impair social development.[60]

Folic acid

Increased intake of folic acidby pregnant women roughly coincides with the reported increase in the prevalence of autism. The explanation offered is that Folic Acid allows more brain cells to survive than should. This hypothesis is untested at this point. [citation needed]

See also

  • Neurodiversity
  • Perpetual child
  • Vaccine controversy


  • CPA-APC.org- Diagnosis and Epidemiology of Autism Spectrum Disorders Lee Tidmarsh, MD, Fred R Volkmar, MD, The Canadian Journal of Psychiatry, Vol 48 pp 517–525, 2003
  • NIH.gov- 'The changing prevalence of autism in California', L.A. Croen, J.K. Grether, J Hoogstrate, S Selvin, Journal of Autism Developmental Disorders Vol 32, No 3, pp 207-15, June, 2002
  • NIH.gov-'The epidemiology of autistic spectrum disorders: is the prevalence rising?', Lorna Wing, D. Potter, Ment Retard Dev Disabil Res Rev, Vol 8, No 3, pp 151-61, 2002
  • NIH.gov- 'Prevalence of autistic spectrum disorders in Lothian, Scotland: An estimate using the 'capture-recapture' technique', M.J. Harrison, A O'Hare, H. Campbell, A. Adamson, J McNeillage, Arch Dis Child. May 10, 2005
  • NIH.gov- 'The incidence of autism in Olmsted County, Minnesota, 1976-1997: results from a population-based study', W.J. Barbaresi, S.K Katusic, R.C. Colligan, A.L. Weaver, S.J. Jacobsen, Arch Pediatr Adolesc Med, Vol 159, No 1, pp 37-44, January, 2005
  • NEJM.org- 'A Population-Based Study of Measles, Mumps, and Rubella Vaccination and Autism' Kreesten Meldgaard Madsen, MD, Anders Hviid, MSc, Mogens Vestergaard, MD, Diana Schendel, PhD, Jan Wohlfahrt, MSc, Poul Thorsen, MD, Jørn Olsen, MD, and Mads Melbye, MD, New England Journal of Medicine, Vol 347, No 19, pp1477-1482, November 7, 2002
  • ParentAdvocates.org- 'MMR – Autism Epidemiological Studies: Just a distraction', F. Edward Yazbak, MD, FAAP
  • Unraveling the Mystery of Autism and Pervasive Developmental Disorder : A Mother's Story of Research & Recovery, Karen Seroussi, Broadway Publishing, 2002

External links

Background issues on autism epidemiology

  • About.com- 'The Puzzling Reality of an Autism Epidemic', Floyd Tilton
  • NeuroDiversity.com- 'Prevalence of Autism'
  • NeuroDiversity.com- 'The "Autism Epidemic" & Real Epidemics' (and reply from the M.I.N.D. Institute Director, confirming inappropriate use of "epidemic" to describe autism prevalence'), Kathleen Seidel
  • NIDs.net- (press release) Neuro Immune Dysfunction Syndromes Medical Advisory Board and Research Institute (March 31, 2002)
  • PediatricServices.com- 'The Autism Epidemic'
  • ScienceDaily.com- 'The Age of Autism: What epidemic?', Dan Olmsted, Science Daily (August 1, 2005)
  • ScienceDaily.com- 'The Age of Autism: The Amish anomaly', Dan Olmsted, Science Daily (April 18, 2005)
  • Scoop.co.nz- 'Pharma's Poisoned Generation', Evelyn Pringle, Scoop Independent News (November 29, 2005)
  • SFGate.com- 'State autism rate confounds experts: 273% increase in 11-year span', Katherine Seligman, San Francisco Chronicle (October 18, 2002)
  • TheAge.com.au- 'Number of disabled students soars' Chee Chee Leung The Age (April 26, 2005)
  • TMCNet.com- 'Parents say autism is an issue across the globe' (January 11, 2006)

Attribution to vaccines suggested or alleged

  • Autisme.net- 'The Autism Explosion', Bernard Rimland, Ph.D.
  • AutismCanada.org- 'The Autism Epidemic is Real, and Excessive Vaccinations are the cause' Bernard Rimland, PhD (July 14, 2003)
  • Independent-Media.tv- 'UK Psychologist Says Definite Link Between Vaccines & Autism', Evelyn Pringle (March 7, 2005)
  • InformedChoice.info- 'MMR vaccine and the autism epidemic: In a compulsory inoculation program, it is the responsibility of the developers, promoters and enforcers to prove safety and efficacy'
  • MSNBC.com- 'A coverup for a cause of Autism? RFK Jr. explans how ingredient in vaccines may have contributed to spread' (interview transcript), MSNBC(June 22, 2005)
  • WorldNetDaily.com- 'Vaccines fueling autism epidemic? Report: U.S. infants exposed to mercury beyond EPA, FDA limits' Kelly Patricia O'Meara (June 9, 2003)
  • VaccinationNews.com- 'Autism Prevalence'

Attribution to vaccines uncertain or refuted

  • AAP.org- 'Study Fails to Show a Connection Between Thimerosal and Autism', American Academy of Pediatrics (May 16, 2003)
  • Autism-RxGuideBook.net- 'A Population-Based Study of Measles, Mumps, and Rubella Vaccination and Autism', Kreesten Meldgaard Madsen, MD, Anders Hviid, MSc, Mogens Vestergaard, MD, Diana Schendel, PhD, Jan Wohlfahrt, MSc, Poul Thorsen, MD, Jørn Olsen, MD, and Mads Melbye, MD
  • NationalAcademies.org- 'MMR Vaccine and Thimerosal-Containing Vaccines Are Not Associated With Autism, IOM Report Says'
  • MMRtheFacts.nhs.uk- MMR News and Research from the British National Health Service

Genetic vulnerability and the 'geek syndrome'

  • BBC.co.uk- 'Autism link to "geek genes"' (August 14, 2002)
  • Edge.org- 'The Assortative Mating Theory: A Talk with Simon Baron-Cohen' (April 6, 2005)
  • Wired.com- 'The Geek Syndrome: Autism - and its milder cousin Asperger's syndrome - is surging among the children of Silicon Valley. Are math-and-tech genes to blame?' Steve Silberman Wired (December, 2001)
  • WUStL.edu- 'Autism's genetic structure offers insights' Jim Dryden Washinghton University Record (May 13, 2005)

Pervasive developmental disorders/ Autistic spectrum| See also: List of autism-related topics
Diagnoses: Autism| Asperger syndrome| Childhood disintegrative disorder| Conditions comorbid to autism| Fragile-X syndrome| Rett syndrome| PDD-NOS| Sensory Integration Dysfunction

Controversy: Andrew Wakefield| Autism epidemic | Autism rights movement| Biomedical intervention for autism| Chelation therapy| Generation Rescue| Heritability of autism| Neurodiversity| Refrigerator mother

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