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Blaxill, Nevison, Zahorodny: California Autism Prevalence Trends from 1931-2014 and Comparison to National ASD Data from IDEA and ADDM

JADDCalifornia autism prevalence trends from 1931-2014 and comparison to national ASD data from IDEA and ADDM  authored by Mark Blaxill, Cindy Nevison and Walter Zahorodny was published last night in the Journal of Autism and Developmental Disorders (JADD).  The paper is Open Access and can be found at this link. Congratulations and thank you to Mark, Cindy and Walter.

California autism prevalence trends from 1931-2014 and comparison to national ASD data from IDEA and ADDM


Time trends in U.S. autism prevalence from three ongoing datasets [Individuals with Disabilities Education Act, Autism and Developmental Disabilities Monitoring Network, and California Department of Developmental Services (CDDS)] are calculated using two different methods: (1) constant-age tracking of 8 year-olds and (2) age-resolved snapshots. The data are consistent across methods in showing a strong upward trend over time. The prevalence of autism in the CDDS dataset, the longest of the three data records, increased from 0.001% in the cohort born in 1931 to 1.2% among 5 year-olds born in 2012. This increase began around ~ 1940 at a rate that has gradually accelerated over time, including notable change points around birth years 1980, 1990 and, most recently, 2007.


cia parker

I forgot the flu vaccine, recommended for the first time for all children in 2004. Another disastrous recommendation.

Jeannette Bishop

@NH, thank you very much.

cia parker

1940 reflects the outcome of mercury being put into the diphtheria vaccine in 1932. It took years for the results to become obvious. 1980 reflects the addition of the MMR to the schedule in the '70s. 1990 reflects the addition of the Hib and the hep-B series around that time. 2007 reflects the addition of Prevnar and hep-A in the early oughts. Varicella was added around 1995 and Gardasil around the same time, apparently no upward bump for those, but Gardasil was never on the infant vaccine schedule.


I came across this info from a Dr Mercola article 2013.

The acellular pertussis vaccines that were licensed in 1996 for infants to replace reactive whole-cell pertussis vaccines contain lower levels of certain toxins (such as endotoxin) as well as purified antigens instead of all the components of whole killed B. pertussis bacteria.

Donna L.

Big congrats on getting this published, Mark! And thank you for all you do.
If you ever get the chance, it would be great if you could dumb this study's findings down to like a preschool level for all of us sleep-deprived, barely functioning autism parents. (I sure hope I'm not the only one!) Congrats again!

Jeannette Bishop

This discussion may weigh in to the change around 1990:

Jeannette Bishop

@Allie, from what I understand at least one data set they used was looking 8 year olds only (I gathered that some data sets used involved tracking multiple ages, and at this point I can't begin to describe with any understanding all the analyses performed), but the abstract does describe 1980, 1980, 1990 and 2007 as "birth years" around which "notable change points" occur.


@Jeanette Bishop
Remember that these autism rates are for EIGHT-YEAR-OLDS. So a spike in 1980 would be for children born in 1972.

MMR was introduced sometime during 1971. 1972 would have been the first full year all or most children received it.

Jeannette Bishop

Thank you for conducting all these analyses.

re 1940, 1980, 1990, 2007:

I assume 1940 was essentially when individuals with autism began to be evaluated, after a decade of ethyl-mercury use in vaccines and other applications.

@ approx. 1980, I noted on this timeline, , that measles was targeted for elimination (in the Americas I think) in 1978 with a huge decline noted in 1981, and then in 1979 the "improved" rubella vaccine ( ) using Wistar RA27/3 strain (using aborted fetal tissue/cell lines, I believe) was licensed. So I'm wondering if that combination meant a greater push to use an MMR vaccine (perhaps a vaccine with that rubella strain), and I wonder if an "eradication campaign" meant more vaccines were being administered for other diseases in the process? Also perhaps to be considered, if this rubella strain provoked a stronger immune response in children than prior rubella vaccines and was a live attenuated strain, how often were cases of horizontal transmission occurring, possibly subclinically? Are there any suspected subclinical cases of CRS resulting in autism on record? Or did they possibly vaccinate pregnant women who didn't have a recorded history of natural rubella with the new rubella vaccine? I believe I've heard at least one anecdote of this happening to some.

For 1990, we know the 1986 NCVIA and/or parts of the current "vaccine court" system (for some reason not noted in the timeline link above, but it's in this link: ) go into effect around 1989 and the Hib vaccine is added to the schedule around 1989 (I can't get a good feel for when vaccines, this vaccine in particular, are going into infants verses when "recommended") and HepB in 1991. They also start giving a second MMR (noted in the second timeline) in 1989 (that "Low vaccination rates lead to outbreaks" is pretty disingenuous in the first timeline). One question I have is when did the switch from P to aP for whooping cough vaccination effectively occur in the U.S.?

Also, just remembered this change to MMR in 1990:

For 2007, ? I know they were encouraging pregnant women in some and eventually all trimesters to get flu vaccinations in the range of about years 04-06. I remember a lot of discussion of how many were just doing that without question and now asking for thimerosal free versions was not being recommended, but I'm not sure of the exact year when this became really prevalent. Interesting that MMR was reformulated to somewhat lower levels of mumps antigen in 2007, also. My impression is that wireless technology really rises in prevalence around this point in time also.

John Stone

Just to supplement this important analysis with my letter about UK data to BMJ Rapid Responses in response to Zwaigenbaum and Penner 'Autism spectrum disorder: advances in diagnosis and evaluation'
BMJ 2018; 361 doi: (Published 21 May 2018), also published on 21 May 2018. It documents the rise in autism diagnosis in the school population from 0.2% for those born between 1984 and 1988, as recorded in 1999 (that is for Pervasive Development Disorder) and the scatter of figures for the present time depending on location and perhaps the relative completeness of the figures. These include a rate of 4.7 in Belfast, and possibly even 10% among young children in London:-

I have read this review with interest but disquiet [1]. There is perhaps little point in talking about a global prevalence of autism, which Zwaigenbaum and Penner place according to literature at between 1 and 1.5% if autism is rising dynamically in many parts of the world including the United Kingdom - as I have been recently detailing in the columns of BMJ on-line [2]. For instance, recent data from Northern Ireland showed an overall prevalence in schools there of 2.9%, having risen from 1.2% nine years ago, but there are also big disparities between economic classes and town and country, while in Belfast the rate was 4.7% [3,4]. Unfortunately, as Zwaigenbaum and Penner point out diagnosis is characteristically delayed so the true rates are likely much higher.

The rate that be can be established for England from education figures may be at the top end of official estimates at 1.5% but is rising steeply year on year - the rate of Pervasive Development Disorder (the widest possible category of Autistic Spectrum Disorders) for those born between 1984 and 1988 in the United Kingdom was recorded in official data as being 0.2% in 1999. The present figure from Scottish schools data is around 2.2%. However, dramatic reports appear from around the country [2], notably a report from S.W. London where five London boroughs geared to already diagnosing 750 cases a year were confronting almost double that number a year ago . Extrapolated across the capital that might be 10,000 cases a year, which would possibly be in the 10% region [5]. I have argued that still without any officially accepted explanation for this phenomenon - and certainly Zwaigenbaum and Penner provide none - we are on the brink of population catastrophe. They state:

"Lifetime societal costs related to services and lost productivity by patients and their parents average $1.4m (£1.0m; €1.1m) to $2.4m in the United States and £0.9-£1.5m per child in the United Kingdom, depending on comorbid intellectual disability. When the prevalence of ASD is factored in, the annual estimated societal costs of ASD are $236bn in the US and $47.5bn in the UK."

However, most autism parents know from experience that these are very modest or even delusorily low estimates. Even in 2001 Järbrink and Knapp estimated an average lifetime cost per case in the UK as £2.4m (perhaps £3.8m in today's money) though they thought the overall prevalence was 5 in 10,000, which it perhaps still was in the adult population [6].

We come back in the end to the reality that when it comes to what could be driving these changes to our society the authors neither acknowledge the problem, or have any explanation of it. I fear they may be fiddling as Rome burns.

[1] Zwaigenbaum L, Penner M, 'Autism spectrum disorder: advances in diagnosis and evaluation', BMJ 2018; 361 doi: (Published 21 May 2018)
[2] Responses to Viner RM, 'NHS must prioritise health of children and young people',
[3] John Stone, 'Re: NHS must prioritise health of children and young people - 1 in 21 children in Belfast now have an autism diagnosis' 13 May 2018,
[4] Information Analysis Directorate 'The Prevalence of Autism (including Asperger Syndrome) in School Age Children in Northern Ireland 2018', published 10 May 2018,
[5] John Stone, 'Re: NHS must prioritise health of children and young people - what about autism?' , 19 March 2018,
[6] Järbrink K, Knapp M, 'The economic impact of autism in Britain', Autism. 2001 Mar;5(1):7-22.

Vicki Hill

Good job! I would just note that they focused (for good reasons) on 8 year olds. There has also been an increase in children diagnosed with mental health problems. Those may 'mask' some of the autism symptoms, so that children with significant mental health issues may not receive an autism diagnosis until a later date. (My own son received his first mental health diagnosis at age 8...but the autism diagnosis at age 12.)

Bottom line: the increase proven in this report is conservative; the likely true increase may well be higher.

Angus Files

Hats off to you guys a lot of research in that and expertly documented.

Pharma For Prison



1940,1980, 1990 and, most recently, 2007.

Anyone has an idea what happened in these years? Diagnostic change? Changes in the vaccine schedule? New vaccine technologies?


I am so impressed. Clever, excellent job!

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