Reading Age of Autism Part 2 – Mercury still not good for you

10 Oct

OK, so you might’ve seen by my tweets that I struggled a bit with Chapter 2. I hope the narrative picks up in upcoming chapters.

Anyway, the overall gist of Chapter 2 is that of Chapter 1 – mercury is bad for you, m’kay? To which the the retort is still – Holy Obvious Batman!

The tale of Chapter 2 is how the beginning of the Psychoanalysis movement (an easy mark, being bollocks) missed the ‘obvious’ signs – that Freud/Charcot/Breuer etc diagnosed hysteria when they should’ve diagnosed (you guessed it) mercury poisoning.

Now call me picky but isn’t this book, called The Age of Autism, supposed to be about ‘y’know, autism? I mean, don’t get me wrong, I appreciate the authors are setting out a hypothesis here and doing a bit of scene setting but who really gives a shit these days if Anna O. Dora etc were really cases of mercury poisoning when what we’re supposed to be doing is linking mercury poisoning to _autism_ ?

In fact, this scene setting is doing quite a lot of harm to the Blaxill/Olmsted hypothesis. They go through some of the symptoms of the respective case studies in painstaking detail. Lets look at them in the context of _autism_ shall we?

Charcot diagnosed hysteria in a nurse called ‘Etch___’ a Nurse in Bordeaux. She was nearly raped and descended into a ‘nervous state’ and a convulsion a year later was attributed to the near rape. She returned to work (in Paris though) but suffered:

…repeated and more frequent convulsions, urinary retention, paralyses and other complications…

Page 66

Blaxill and Olmsted claim these as symptoms of mercury poisoning. They may well be. But I tell you what – they sound *nothing* like autism.

Charcort also examined another patient who showed the following symptoms:

…comatose for half an hour and in bed for two days; afterward he continued to exhibit classic symptoms of decreased sensation, twitching and vision loss…

Page 67

I mean, does that sound anything like autism to you?

Blaxill and Olmsted recount a myriad of other symptoms including limb paralysis, hallucination, a relentless cough, paresis and many many more. They’re unified in Blaxill and Olmsted’s minds by their obvious connection to mercury poisoning – maybe they are. But vastly more obvious to me, if not to them, is that they’re unified in presenting a medical picture that is about as far removed from autism as its possible to get.

Reading Age of Autism Part 1 – An Unhidden Agenda

10 Oct

The first chapter of Age of Autism (called The Age of Syphilis) could easily have been summed up in one short sentence: Mercury is bad m’kay? Well no shit Sherlock(s). We all know that.

Taking us an a tour (and the book _is_ reasonably well narrated and edited) through the insane asylums of various European countries, through the lack of association of mercury poisoning and indigenous races of various countries, the two authors end up in Vienna and (place tongue in cheek) in a bombshell moment of horror, reveal their idea that Mozart might’ve died of mercury poisoning. Hardly a new idea. According to Wikipedia, Mozart has been suggested to have died from over 100 different things but the most likely is acute rheumatic fever.

What makes Age of Autism different from most is that they posit that Mozart’s mercury poisoning (if he was which is in doubt) came about whilst he was trying to cure Syphilis. Indeed, you could get the idea from reading Age of Autism that just about everyone in the world from the 1600’s onwards died of mercury poisoning whilst treating syphilis.

Lurking underneath this first chapter with its autism-free mundane plodding from situation to situation is where the authors reveal one of the main themes of the book.

…the best medical minds in Europe were slow to realize…

Page 24

But the notion that medicine might have been that habit just didn’t occur to [them] – perhaps because it could only mean that doctors were causing the worst manifestation of syphilis. And that was simply inconceivable.

Page 29

Not using ‘recognized forms of treatment’…may have spared the American Indians the brain lesions symptomatic of neurosyphilis.

Page 30

Despite all the evidence and concern, the heart of the medical profession remained committed to mercury treatment, and mainstream physicians rose strongly to its defense.

Page 32

I’m sure you don’t need more examples but trust me – they’re there. Anyway, as you can see Age of Autism is not _just_ a book about mercury being bad (m’kay?) its also a book about mainstream medicine and how stupid and purposefully evil it is as well as how frickin’ great complementary medicine is. Take a look at those quotes again. “See?” B & O seem to be screaming hysterically, “See? Look – even back then they were useless, these ‘doctors’…its just like now with The Vaccines!!!”

I mean don’t get me wrong – the mercury treatments of Syphilis were frequently worse than the disease but lets compare the trace amount of mercury in paediatric vaccines these days to a passage from Age of Autism:

Patients coated in mercury often stayed wrapped in bedclothes for weeks…[t]hey sat in baths saturated with mercury or squatted on stools above a steaming cauldron of it…

Page 31

So lest we forget, these two medical procedures, one commonly known as a ‘targeted precise injection’ and one known as ‘slopping that shit on with a spoon’ are not really comparable. So far, this is one of the main (though not only) weakness of the book – its comparing apples with oranges.

My latest book

9 Oct

I’d like to thank the anonymous donor who sent me a copy of Age of Autism – the book. It arrived this morning. So for the next few days I’m going to put aside the unabashed joy of reading Under the Dome by Stephen King and take up this newer work of fantasy. I promise to blog everything I can.

A sense of civil discourse

8 Oct

Mark Blaxill and Dan Olmsted have been on a book tour for their new book, The Age of Autism. In a radio interview they were asked about being attacked, Mr. Blaxill responded:

“We get attack on a regular basis. I think we have become accustomed to that. I think that one things we really need to recover in this debate is a sense of civil discourse”

Mr. Blaxill made a similar call for a more civil discourse about a year ago. This was in regards to a post that was so offensive that the Age of Autism blog had to pull it down. Before it was pulled, Mr. Blaxill defended the piece. Mark Blaxill’s comment? He supported the attack as “edgy”.

The irony is fairly thick. Toadies who do hit jobs in the media?!? What was that blog piece but a hit job in a form of the media?

What is strange is the repeat of the statement that the discourse should be more civil. In that, I agree with Mr. Blaxill’s commentsl. Where we part ways is in the definition of civil discourse. I just don’t think he and his team at the Age of Autism blog have promoted a civil discourse in the last year (or ever).

Dan Olmsted owns/runs the Age of Autism blog. Mark Blaxill is an “editor” blogger there and frequent commenter. They are

Shall we go down the list of the people who have been personally attacked by that blog? Peter Bearman, Tom Insel, Story Landis, Richard Grinker (and his wife), Ari Ne’eman…the list goes on.

These are not “edgy” blog posts. These have included false claims of pharmaceutical ties levied against a blogger combined with an effort by Age of Autism readers to make the blogger lose his day job.

A more civil discourse would be welcomed. Even an edgy discourse would be welcomed. I encourage Mr. Blaxill and Mr. Olmsted to put substance behind the words. Stop the hot pieces. Stop the attacks.

New National Autism Clearinghouse In The Works

7 Oct

Disability Scoop has an article, New National Autism Clearinghouse In The Works, which states:

A handful of disability organizations are joining forces to establish a national resource center to assist people dealing with autism and other developmental disabilities.

The new initiative known as Autism NOW: The National Autism Resource and Information Center will be established by The Arc in collaboration with the Autistic Self Advocacy Network and Self Advocates Becoming Empowered with the help of $1.87 million awarded by the Department of Health and Human Services this week. Autism NOW will be tasked with helping people connect with services and interventions in their own communities.

Here is the press release from The Arc:

Washington, DC – The Administration on Developmental Disabilities (ADD), within the Administration for Children and Families (ACF) at the U.S. Department of Health and Human Services, announced yesterday that The Arc would receive an award of $1.87 million for fiscal year 2010 to establish a national resource and information center on Autism Spectrum Disorder (ASD) and other developmental disabilities.

The Arc, in collaboration with several key partners will implement an innovative and dynamic initiative, called Autism NOW: The National Autism Resource and Information Center to engage and leverage a national network of disability, aging, military, and family organizations to deliver information and resources relevant to individuals with ASD and other developmental disabilities.

“The Arc and our partners are primed and ready to build a dynamic resource to address the needs of people with ASD and other developmental disabilities through this national network. We are proud to have the opportunity to launch Autism NOW, a much needed resource. It is especially significant that self-advocates will have a meaningful role in leading, implementing and realizing the goals of this innovative project,” said Peter V. Berns, CEO of The Arc.

Other partners include the Autistic Self Advocacy Network (ASAN), and Self Advocates Becoming Empowered (SABE) to provide expertise from the self-advocate perspective. For research expertise in key areas across the lifespan in ASD and other developmental disabilities, The Arc has partnered with members of the Association of University Centers on Disabilities (AUCD) Network, also referred to as UCEDDs (University Centers on Excellence in Developmental Disabilities), the Institute for Community Inclusion from the University of Massachusetts, the Developmental Disabilities Institute from Wayne State University, and the Center for Community Inclusion and Disability Studies from the University of Maine.

First Autistic Presidential Appointee Speaks Out

7 Oct

Wired Magazine has an interview with Ari Ne’eman, Exclusive: First Autistic Presidential Appointee Speaks Out. Mr. Ne’eman has been appointed by the Obama administration to to positions: a seat on the Interagency Autism Coordinating Committee (IACC) and a seat on the National Council on Disability (NCD).

The author of the Wired piece, Steve Silberman, also blogs at PLoS. His piece there is No More Pity: The First Openly Autistic White House Appointee Speaks Out.

The Wired piece does touch on the opposition to Mr. Ne’eman’s appointment. I am grateful that this an other side issues are also met with a real discussion of what Mr. Ne’eman’s views are. I wish there even more of that discussion. Here is a small sample:

Very few of us wake up in the morning and think, “Have they developed a proper mouse model for autism yet?” Instead, autistic people and their parents worry about finding the educational and support services that they need.

As a parent, I appreciated this question and answer:

Wired.com: What advice would you give to neurotypical people who want to become effective allies of the autistic community?

Ne’eman: At the political level, watch where your money is going. There are a lot of well-meaning people who think they’re helping us by donating to Autism Speaks or other groups looking for a cure. It would be better for people to get involved in their local communities and ask tough questions like, “Is my school inclusive? Is my workplace willing to hire autistic people and other people with disabilities?”

Given Mr. Ne’eman’s recent appointments, I felt this was probably the key question of the interview:

Wired.com: What do you hope to accomplish in Washington?

Ne’eman: All across the country, we have hundreds of thousands of people on waiting lists for access to community services. People with disabilities don’t have the support we need to live independently, be employed, and participate in civic life. Instead, because of a bias in the way Medicaid is structured, many of us are segregated in institutions, which offer a much lower quality of life to disabled people at the same time that it works out to be much more expensive. It’s easier to get states to pay for an institution than to get them to allow people to access services in their homes. Making community services more accessible would be a huge game changer for all kinds of people with disabilities.

Passing one particular piece of legislation — the Community Choice Act — would accomplish that. The Community Choice Act would make it so that states would be required to pay for supports and services at home or in the community, but it would actually save money, because institutional placements are very expensive. There’s no reason not to do this.

Free and Appropriate Education?

6 Oct

I’m a bit short of time this morning so couldn’t give this story the time it deserved. The following is a cut and paste job from Fox Houston:

Dreams brought Kenneth Chibuogwu to America and in time determination brought many of those aspirations within reach.

“I worked hard. I came to this country with nothing,” says Kenneth.

It is a country this father and husband have deeply embraced, along with its core convictions.

“If you don’t stand up for something, you’ll fall for anything,” he says.

And what could be more worthy of battle than his first born son, Chapuka, “Chuka” for short a child who will spend each and every day of his life challenged with autism?

“This child was a gift from God,” insists Kenneth.

Guaranteed by federal law a “free and appropriate education” for their son, Kenneth and wife Neka hoped the Alief School District would prove an able partner in helping Chukka reach his potential.

It didn’t happen.

“When I went there I saw things no mother would want to see,” says Neka her visits to Chuka’s middle school.

“My wife went to observe, found him squashed in the corner and nobody cared,” says Kenneth.

“There was nothing I could do but cry because I was so shocked that such a thing could go on in this country,” added Neka of the repeated conferences with Alief administrators ending in stalemate.

In Texas when parents and educators can’t agree on whether a school district is giving a disabled student all that the law demands the state offers a procedure called “due process” where a sort of education judge listens to all the evidence and decides the issue.

In May of 2007, using much of their life savings, Chuka’s parents filed their case.

Instead of seeking compromise, Alief launched a full-blown legal counterattack alleging the case was “improper” and that the Chibuogwus “harassed” district employees during meetings.

“Nobody in this household harassed the school district. I feel that they harassed us,” insists Neka.

“These people had been railroaded, these people had been maligned,” says special education advocate Jimmy Kilpatrick who represented Chuka and his parents.

Drained and discouraged, Kenneth and Eka dropped their due process case and Chuka never returned to class.

The conflict could have ended there, but Alief Superintendent Louis Stoerner and then board president Sarah Winkler had other plans.

The District sued the economically distressed parents of a special needs child for every penny of the district’s legal expenses, an amount, at the time approaching $170,000 dollars and now estimated at close to a quarter million.

“What I feel is that they are trying to bully me for asking for a chance for my son¿s life,” says Kenneth.

Alief taxpayer and watch dog Bob Hermann sees the lawsuit as senseless and mean spirited.

“I don’t know why we would spend taxpayers money to try and punish somebody who doesn’t have the money and are probably going to win at the end of the day anyway,” says Hermann.

Those who represent special needs families suspect a larger more sinister scheme.

“What they are trying to do is send a chill down parent’s spine about advocating for their children,” says Louis Geigerman, president of the Texas Organization of Parents, Attorneys and Advocates.

“Lets set some examples, lets hang a few of them at high noon right out here in the middle of the town square and show you what we do to people who want to advocate for their children,” adds Kilpatrick.

“If I don’t fight them, you know they are going to do it to other parents,” says Kenneth Chibuogwu.

This past April after three long and expensive years of legal warfare a federal judge here in Houston issued his ruling. Alief I.S.D. was wrong and had no right under the law to collect legal expenses from Chuka’s parents.

Instead of accepting the ruling, superintendent Stoerner and apparently the Alief School board have chosen to risk even more taxpayer dollars and appeal the ruling to the 5th Circuit.

At a board meeting, by phone and by e-mail Fox 26 news has repeatedly asked the Alief decision makers “Why” and have yet to receive an answer.

A district spokeswoman promised comment after the appeals court rules.

“We’ve almost lost everything trying to keep this up,” says Neka.

“What basically there are trying to do is run me and my family on to the street,” says Kenneth

While school expenses are generally available for public inspection Alief has attempted to block our opens records request.

FOX 26 News has however obtained invoices which show the district’s taxpayers have compensated Erik Nikols and his Law firm Rogers, Morris and Grover as much as $12,000 in a single month for waging the three-and-a-half year courthouse campaign against the Chibuougwu’s.

The meter, presumably, is still running.

“I know a lot of people have gained from this, a lot of people have been enriched by this,” says Neka.

As for Chuka, he’s now fourteen, attends no school and for five years hasn’t received a single minute of the free and appropriate public education that is his right

Their child, his parents insist, has been thoroughly left behind.

A look back on autism blogging

6 Oct

A post on Autism Street is entitled “Epilogue“. In it, Do’C gives a look backwards on his experiences online in the past few years. Autism Street was one of my mainstays when I first started reading blogs. Before reading autism blogs I had almost no exposure to blogs. I can’t recall how exactly I got into reading blogs but I recall some of the ones I read.

Obviously, I’ve read Kev’s blogging for some time. I was reading when the domain name was under his name and not LeftBrainRightBrain. I met Do’C once and he asked me how I used to find the blogs to read. I told him that I would take some of the sites with long blog rolls (LBRB being one, Neurodiversity.com being another) and would just go down the blog roll, reading whatever was new on each blog.

A lot of the blogs I’ve read have either stopped or slowed down. A lot of them I don’t remember. But here are some of them.

AutismDiva. The Diva has retired. For those who keep speculating, yes, she is retired and not morphed into some other online persona. The Diva was a persona, not the personality of the actual blogger. The Diva had an amazing wit, and it bothered many who were the target. I think it sometimes masked the fact that the Diva cared a lot about autistic people. The Diva gave me some of the best advice I got as a blogger. One piece was that bloggers should give themselves permission to stop.

I find it very strange that it has been three years since the last Diva post.

Asperger Square 8. A different brand of humor than the Diva, but amazing humor at the same time. Again, the real message was under the humor. Square 8 is not very active these days and I miss that very much.

I recall when Kev first blogged about a Autism News Beat. This is not a high-quantity blog, but again a sharp wit and some amazing pieces. ANB works from a journalist’s perspective. He has attended alt-medicine conferences and reported on them.

A Photon in the Darkness blog is and has been a great resource. Prometheus has been blogging since 2005. Prometheus has an a level of scientific expertise which is rare in blogging. Not absent, but rare.

No blogger is as thorough as Kathleen Seidel at Neurodiversity.com. Her series on the Geier’s revealed questionable institutional review boards, questionable therapies, well, lots of questions about the Geiers. Lots of answers too. Those answers prompted a subpoena from a vaccine-injury lawyer who often hires the Geier team. A subpoena which was quashed, but not until after it made nationwide news.

The Autism Natural Variation blog is and has been one of my favorites. There was a time when every three months the California Department of Developmental Services would put out new statistics. David Kirby and Rick Rollens would immediately use those statistics to claim that vaccines cause autism, and Joseph and Do’C would desconsruct the spin. I recall one time when Mr. Kirby and Mr. Rollens couldn’t agree. One claimed that the autism count went down, one claimed that the count went up. Both claimed this as proof that vaccines cause autism. Joseph and Do’C were always there and always solid with responses.

I could go on and on. There have been so many really good blogs. The ones above are just the few that came readily to mind. What strikes me is that the ones that did come readily to mind are blogs which have largely dropped off in output over time.

What is very interesting at this time is the reformulation of the Autism Hub. Many of the older blogs, some very good newer ones. One new one that caught my eye is Corina Becker’s “No Stereotypes Here” and another “new” blog is Kristina Chew’s “We go with him“. Krisina Chew amazed me with her prolific blogging in her old blog.

The above are just observations and memories, not a list of “top” blogs or anything of that sort. Just a few of those which stand out in my memory today. Tomorrow the list may be different.

Sibling Recurrence and the Genetic Epidemiology of Autism

5 Oct

As if to follow up on the Social Demographic Change and Autism paper we recently discussed here on LeftBrainRightBrain, a new paper on autism recurrence risk in families came out today. Sibling Recurrence and the Genetic Epidemiology of Autism is from a team from the Kennedy Krieger Institute at the Johns Hopkins University. From the abstract I would guess that the study uses the IAN Database.

The authors find about 11% recurrence risk, much higehr than the prevalence of autism (about 1%) and quite similar to that of the Bearman group. Further, the Kennedy Kreiger team find that about 20% of non-autistic siblings have a history of language delay.

Am J Psychiatry. 2010 Oct 1. [Epub ahead of print]
Sibling Recurrence and the Genetic Epidemiology of Autism.

Constantino JN, Zhang Y, Frazier T, Abbacchi AM, Law P.

Departments of Psychiatry and Pediatrics, Washington University School of Medicine, St. Louis; the Center for Autism, Cleveland Clinic, Cleveland; and the Kennedy Krieger Institute, Medical Informatics, Baltimore.
Abstract

Objective: Although the symptoms of autism exhibit quantitative distributions in nature, estimates of recurrence risk in families have never previously considered or incorporated quantitative characterization of the autistic phenotype among siblings. Method: The authors report the results of quantitative characterization of 2,920 children from 1,235 families participating in a national volunteer register, with at least one child clinically affected by an autism spectrum disorder and at least one full biological sibling. Results: A traditionally defined autism spectrum disorder in an additional child occurred in 10.9% of the families. An additional 20% of nonautism-affected siblings had a history of language delay, one-half of whom exhibited autistic qualities of speech. Quantitative characterization using the Social Responsiveness Scale supported previously reported aggregation of a wide range of subclinical (quantitative) autistic traits among otherwise unaffected children in multipleincidence families and a relative absence of quantitative autistic traits among siblings in single-incidence families. Girls whose standardized severity ratings fell above a first percentile severity threshold (relative to the general population distribution) were significantly less likely to have elicited community diagnoses than their male counterparts. Conclusions: These data suggest that, depending on how it is defined, sibling recurrence in autism spectrum disorder may exceed previously published estimates and varies as a function of family type. The results support differences in mechanisms of genetic transmission between simplex and multiplex autism and advance current understanding of the genetic epidemiology of autism spectrum conditions.

Social Demographic Change and Autism: part 2

3 Oct

Prof. Peter Bearman’s group is studying the causes for the rise in autism prevalence, using data from the California Department of Developmental Services. I recently wrote a rather long introduction to their recent paper, Social Demographic Change and Autism.

The study abstract is here:

Social Demographic Change and Autism
Liu K, Zerubavel N, Bearman P.

Abstract

Parental age at child’s birth–which has increased for U.S. children in the 1992-2000 birth cohorts–is strongly associated with an increased risk of autism. By turning a social demographic lens on the historical patterning of concordance among twin pairs, we identify a central mechanism for this association: de novo mutations, which are deletions, insertions, and duplications of DNA in the germ cells that are not present in the parents’ DNA. Along the way, we show that a demographic eye on the rising prevalence of autism leads to three major discoveries. First, the estimated heritability of autism has been dramatically overstated. Second, heritability estimates can change over remarkably short periods of time because of increases in germ cell mutations. Third, social demographic change can yield genetic changes that, at the population level, combine to contribute to the increased prevalence of autism.

They start by noting their group’s previous work which showed an increased risk for autism based on both maternal and paternal age.

There is a strong relationship between parental age and autism. The one study (King et al. 2009) that decomposes maternal and paternal age—and confounding cohort effects— identifies maternal age as riskier than paternal age (using the California data deployed in this analysis).

Relative risks were as high as 1.8. These are not as high as the increased risk for Down Syndrome, which can be 10x higher in older mothers, but it is still a notable effect.

The authors note that parental age has increased notably during the 1990’s, the same time that the “autism epidemic” started.

… the proportion of children born whose parents were age 35 or older at birth increased rapidly: from 24.3% in 1992 to 36.2% in 2000.

Many factors have been identified as correlated to the autism increase. Basically anything that increased over the 1990’s could be argued to be correlated with an increase in autism prevalence. Correlation is not causation, as we hear over and over. One must go beyond correlation in order to claim that there is a real effect.

And Prof. Bearman’s group does go beyond correlation. They look at autism in twins and siblings and show that (1) the concordance is much lower than has been previously reported and (2) the concordance is changing with time. They go into detail on the methods in the paper, including how to determine how many twins were “identical” (monozygotic or MZ) vs. fraternal dizygotic or DZ). Here is the table showing the concordance for twins and sibling pairs from the paper, Casewise and Pairwise concordance numbers are given.

Casewise concordance (Pcw) measures the probability that a co-twin will be affected (with a given disorder), given that the other twin is affected. Pairwise concordance (Ppw) measures the proportion of concordant (both twins are affected) pairs in all pairs with at least one twin who is affected.

Pairwise concordance is what most people think of as concordance.

The pairwise concordance is 40% for MZ (identical) male twins and 50% for female twins. Much lower than the higher values from previous, smaller studies which claimed 36-90% concordance. From the paper from Prof. Bearman’s group:

The Evidence for High Heritability of Autism
To date, the strongest evidence supporting the idea that autism is a genetic disorder arises from twin and family studies. Previous twin studies on full syndrome autism have reported high pairwise concordance rates in identical (MZ) twins (36%–96%) and low concordance rates in fraternal (DZ) twin pairs (0%–31%) (Bailey et al. 1995; Folstein and Rutter 1977; Ritvo et al. 1985; Steffenburg et al. 1989). Because MZ twins share 100% of their genes while DZ twins share only around 50%, a large difference between MZ and DZ concordance rates is regarded as strong evidence for genetic infl uences. The recurrence risk of autism in siblings is reported to range from 3%–9%, which is much higher than the population rate of 10 in 10,000 children (Baird and August 1985; Bolton et al. 1994; Piven et al. 1990; Ritvo et al. 1989).3 Relatives of a child with autism are also more likely to have broadly defined autism spectrum traits than controls (Szatmari et al. 2000).

Low concordance is consistent with another recent study, Genetic variance for autism screening items in an unselected sample of toddler-age twins, from Prof. Goldsmith’s group at U. Wisconsin. The abstract is below:

OBJECTIVE: Twin and family studies of autistic traits and of cases diagnosed with autism suggest high heritability; however, the heritability of autistic traits in toddlers has not been investigated. Therefore, this study’s goals were (1) to screen a statewide twin population using items similar to the six critical social and communication items widely used for autism screening in toddlers (Modified Checklist for Autism in Toddlers); (2) to assess the endorsement rates of these items in a general population; and (3) to determine their heritability.

METHOD: Participants composed a statewide, unselected twin population. Screening items were administered to mothers of 1,211 pairs of twins between 2 and 3 years of age. Twin similarity was calculated via concordance rates and tetrachoric and intraclass correlations, and the contribution of genetic and environmental factors was estimated with single-threshold ordinal models.

RESULTS: The population-based twin sample generated endorsement rates on the analogs of the six critical items similar to those reported by the scale’s authors, which they used to determine an autism threshold. Current twin similarity and model-fitting analyses also used this threshold. Casewise concordance rates for monozygotic (43%) and dizygotic (20%) twins suggested moderate heritability of these early autism indicators in the general population. Variance component estimates from model-fitting also suggested moderate heritability of categorical scores.

CONCLUSIONS: Autism screener scores are moderately heritable in 2- to 3-year-old twin children from a population-based twin panel. Inferences about sex differences are limited by the scarcity of females who scored above the threshold on the toddler-age screener.

Back to Prof. Bearman’s study: their analysis went deeper, including measures of the pairwise concordance for non “identical” twins. Opposite sex twins have a 10% concordance, and same sex twins (dizygotic) have 20% concordance. That gender difference in concordance is quite notable.

The risk of having an autistic child is much higher if one already has an autistic child. The recurrance risk is about 10% for full siblings, 3% for half siblings. These values are quite high considering that the autism (not ASD, but autism) prevalence is less than 1%. The recurrence risk is much higher for siblings of an autistic female than autistic male. Male siblings of a female “proband” have a recurrence risk of 18%. Female siblings of a male “proband” have much lower recurrence risk of 5%.

Prof. Bearman’s group has done what may be a first in concordance studies: analyzed data as a function of birth year. “Temperal concordance”. I.e. they ask the question, does the concordance change with time? The answer, yes.

Here are panels (A) and (B) from Figure 1 of the paper.

Panel (A) shows casewise temporal concordance. Concordance increases for single-sex (SS) twins, and decreases for other-sex (OS) twins during the 1990’s. The authors note this is consistent with a de novo mutation mechanism for increased risk for autism. Panel (B) shows that the average age for the twin parents is also increasing over this time period. From the paper:

In panel B, we report change in mean parental age at twin births, which increases steadily during the same period. Recall that because MZ twins are developed from a single pair of matched egg and sperm cells, any de novo mutations will be found in both twins. In contrast, DZ twins develop from two distinct pairs of egg and sperm cells. Because de novo mutations are rare events, the chance that both DZ twins will share the same de novo mutation is extremely low. If de novo mutations have an increasing causal share in the etiology of autism over time, we should expect an increase in the difference between MZ and DZ concordance rates. One mechanism that accounts for de novo mutations’ increasing share of autism etiology is the rise in parental age over our study period, which is likely to lead to increased mutation rates.

One question that naturally arises in regards to multiple births is the use of assisted reproduction technology (ART). The authors discuss this:

Although the genetic influence on autism has been overestimated, it has increased over time due to non-allelic mechanisms. Although the human gene pool does not change substantially over one or two generations, de novo germ-line mutation rates are much more susceptible to rapid social and/or environmental changes (such as rising parental age), and thus can explain the increase in the heritability of autism. Of importance is the fact that although age of parents at birth of twins was signifi cantly higher in 2000 than in 1992, age of parents at the birth of their second-born did not increase over the same period. Thus, the difference between the trends of OS twin concordance and full-sibling recurrence risk may be associated with age of parents. Since the use of assisted reproductive technologies (ART) is associated with the age of parents and has increased radically over the same time period, ART may be implicated in the increased prevalence of autism. Our data show that the increase in the percentage of children with autism born in multiple births (from 3.6% in 1992 to 5.7% in 2000) exceeded that of the percentage of multiple births in all births in California (from 2.1% in 1992 to 2.9% in 2000). This implication requires future investigation.

The risk of autism is higher with multiple births and increased at a greater rate than the percentage of multiple births in general.

The authors discuss the possibility of prenatal exposures to infection or toxicant or a gene/environment interaction might follow the same trends they observe:

It remains possible that other factors have contributed to the diverging trends in the SS and OS concordance. A virus or a toxicant experienced in utero could yield the results that we observe. Specifically, an increasingly prevalent virus (or toxicant) associated with a small risk of autism would lead to increasing concordance of SS twins (who often share the same placenta) and decreasing concordance of OS twins. Similarly, interactions between genes and an increasingly common environmental trigger could also generate the same pattern. However, we believe that an increase of de novo mutations attributable to rising parental age is more parsimonious given the documented rise in parental age, recent findings that link de novo mutations and autism, and the observed associations between concordance rates and parental age reported in this article.

The authors address one concern that I had in reading the paper: what if some change in the way children are qualified for regional center services changed the characteristics of their population. Or, to put it more simply, are the autistics in 2000 really comparable to those in 1990? Regional center data show a decreasing percentage of children also in the mental retardation and epilepsy categories. Could this have an effect on their results? From the paper:

The temporal concordance trend reported in this article is not predicted by a diagnostic expansion theory. If ascertainment and surveillance dynamics rest behind the increase in SS concordance, we would expect to observe increasing rather than decreasing concordance for OS twin pairs over time. The observation of decreasing concordance over time in OS twins challenges the idea that the results we observe are an artifact of reduction of error in diagnosis as a consequence of enhanced surveillance or clearer understanding of diagnostic markers. First, there is no evidence that diagnostic errors have been reduced; second, if this were the case, we should observe the same effect across all pair types. Finally, increasing ascertainment and surveillance would predict heightened recurrence risk for siblings over time. We do not observe any increase in such risk (chi-square statistics of linear trends in proportion = 1.613; p = .204).

The authors’ concluding paragraph is:

For social scientists, there are three important discoveries. First, we show that a sociological eye on the role of genetics yields the insight that de novo mutations may play a signifi cant role in autism etiology. Only by observing changing patterns of concordance over time—that is, historicizing genetic influences rather than essentializing them—could we find evidence of a new causal mechanism underlying autism. Second, by working with a large population-based data set, versus small clinical samples, we have been able to properly estimate the true heritability of autism. These estimates show that autism is far less heritable than previously thought and consequently, explanations for the precipitous increase in prevalence must turn toward environmental and social dynamics often ignored by the scientific research community. Third, we show that the identification of the mechanisms by which social processes operating at the macro level—in this case, increases in parental age—“get under the skin” and shape health outcomes is a proper social science activity.

This study has the possibility to have a major impact on autism causation research. I would not be surprised at all if this ends up as one of the papers highlighted by the IACC for the year. I’m certain that this paper will be brought up in online discussions for some time to come, what with the very different estimate of twin concordance than previously quoted.

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