Archive for the 'autism' Category

Nov 07 2013

Early Detection of Autism

Part of the impetus for the fringe belief that vaccines are somehow causally related to the development of autism is that the signs of autism often become apparent at 2-3 years of age, after children have received many of their routine childhood vaccinations. (Average age at diagnosis is 3.1 years.) In an otherwise healthy child, the vaccines might be the only thing the parents can think of that could be a potential cause.

Signs of autism are not clinically noticeable prior to 6 months of age. From about 6-18 months the signs can be detected by careful clinical observation, but may be missed by parents. During this time parents may become slowly aware that their child is not developing as expected, and the creeping suspicion that something is not quite right often culminates in a diagnosis between age 2-3.

The phenomenon of temporal binding may then cause the parent’s memories to shift over time so that the temporal correlation between getting vaccines and signs of autism appearing become closer together. For some parents this can become a very powerful memory – my child was perfectly normal, then he received vaccines and started to show signs of autism.

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9 responses so far

Jul 29 2013

Legal Courts And Science

Facebook is like a graveyard in a zombie movie, where old news items rise from the dead to have a second life. I am often asked about news items that are burning up Facebook, only to find that they are years old, but never-the-less they have to be addressed all over again. ]

One such item (actually a few items) is a 2012 news report about the Italian courts awarding money to the Bocca family a large reward because it concluded their 9-year-old son acquired autism from the MMR vaccine.

History here is a useful guide. The courts have historically often been out-of-step with the science, tending to err on the side of awarding compensation for possible harm. For example, until about the 1920s it was thought that physical trauma could cause cancer. Animal studies and epidemiological evidence, however, showed that there was no causal connection. Recall bias and increased surveillance were likely the cause of the apparent association.

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10 responses so far

Apr 03 2012

Donald Trump – Anti-Vaccine Crank

From time to time celebrities publicly discuss their opinions on scientific topics, and the results are usually not pretty. I have discussed previously the folly of Jenny McCarthy, for example, in using her dubious celebrity to promote anti-vaccine nonsense. Now The Donald has joined the ranks of people who are mostly famous for being famous who feel their celebrity gives them license to pontificate publicly about complex scientific issues. Trump told a Fox News audience that he strongly believes vaccines are causing the increase in autism diagnosis. He based this upon his scientific training, thorough reading of the relevant scientific literature, and consultation with experts – no, I mean based upon his casual observation and naive assumptions. Hey, he has an anecdote.

Here is the core of his rant:

“I’ve gotten to be pretty familiar with the subject. You know, I have a theory — and it’s a theory that some people believe in — and that’s the vaccinations. We never had anything like this. This is now an epidemic. It’s way, way up over the past 10 years. It’s way up over the past two years. And, you know, when you take a little baby that weighs like 12 pounds into a doctor’s office and they pump them with many, many simultaneous vaccinations — I’m all for vaccinations, but I think when you add all of these vaccinations together and then two months later the baby is so different then lots of different things have happened. I really — I’ve known cases.”

OK, it’s easy for a lay person to get caught up in a complex scientific question and get overwhelmed by information from one side. If you naively watch Loose Change, for example, without being familiar with the whole 911 conspiracy thing you might be led to believe there is something sinister going on. That’s how propaganda of that sort often works – overwhelm your audience with factoids, distorted and cherry-picked information, and apparent correlations and weave them into an emotionally compelling story. If you listen to just one side of any scientific debate you will probably be convinced that that side has a strong and perhaps even iron-clad case. Only when the other side has an opportunity to make their case do you see how the information you were given was systematically biased in one direction.

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22 responses so far

Feb 17 2012

The Autistic Brain at 6 Months

Published by under autism,Neuroscience

Yet another study showing that clear signs of autism are present as early as six months of age has been published. In this study researchers looked a high-risk children (siblings of children with autism) at 6 months with MRI scanning (specifically diffusion tensor imaging) and then evaluated them clinically at 24 months to see which children met criteria for autism spectrum disorder (ASD). Some of the children also had imaging at 12 months. The imaging was used to look at the development of white matter – the tracks in the brain that contain the axons or pathways of communication.

When compared as groups the 28 infants who went on to develop ASD had significantly decreased white matter development in 12 of 15 brain pathways examined in comparison to the 64 infants who did not develop clinical ASD.  These results are very robust, although I should point out that the children were compared as groups, not individuals. The purpose of this study was to see if there were detectable changes in the brains of children with ASD at 6 months, not necessarily to explore its utility as a diagnostic tool that can be applied to an individual.

Still, this study supports other research providing increasing evidence that ASD begins at least as early as 6 months. It is probable that ASD begins earlier than 6 months, actually, because in order for detectable differences to be present in the brain, development must have been heading down a different trajectory prior to that. These kinds of studies have not looked at children younger than 6 months, and it would be interesting to see how early such changes can be detected. But even without that data, we can conclude the whatever process results in ASD it is active prior to 6 months so that the effects are detectable at 6 months.

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13 responses so far

Feb 16 2012

Mercury Still Not Correlated with Autism

Published by under autism,Neuroscience

Another study, published recently in PLoS One, fails to show a correlation between mercury and autism. This was a study of mercury excretion in the urine, comparing subjects with autism to their siblings as well as controls without autism spectrum disorder (ASD), both in mainstream and special schools. They found no significant difference among the groups, even controlling for kidney function (creatinine clearance), age, gender, and amalgam fillings.

To put this study into context – there are those who claim that mercury toxicity is what causes ASD, and in fact ASD is simply misdiagnosed mercury toxicity. There is no question that mercury is indeed a neurotoxin, but toxicity is all about dose, so the question is are children being exposed to mercury in high enough dose to cause toxicity. Further, it is difficult to extrapolate from preclinical studies (in test tubes and petri dishes) to living organisms. We need to further know what happens to the toxin in the body, and how the body handles it.

With regard to the forms of mercury found in some vaccines (although much less than in previous years) and tuna fish, the body seems to rid itself of the mercury sufficiently quickly to prevent build up to toxic levels. Of course, this remains a hot topic because of the persistent claims by the anti-vaccine movement that vaccine cause ASD, and some who cling to the discredited notion that it is mercury in vaccines that is the culprit. There are also the so-called “mercury militia” who blame environmental mercury (from vaccine and elsewhere) on all human illness, not just autism.

As further background, it’s helpful to note the chain of argument that has occurred with respect to the role of mercury in autism. Studies have consistently found no correlation between mercury exposure and the risk of ASD. Proponents of the mercury hypothesis have therefore argued that there is a subpopulation of vulnerable children who metabolize and excrete mercury differently than the general population, and it is within this subpopulation that mercury causes ASD.

Logically this may be true, but the argument is little more than special pleading, although a common one. Scientists are familiar with the usual list of special pleading arguments made to dismiss negative evidence. These include: that the dose studied was too low, the treatment duration was too short, the placebo or comparison treatment was also effective, or the looked-for effect only exists in a subpopulation. Each one of these arguments is logically consistent – if true they would explain the negative results without meaning that the phenomenon is not true. They may even be true in specific cases. What makes them special pleading is when they are invoked ad hoc to explain negative evidence without good justification.

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17 responses so far

Jun 09 2011

The Genetics of Autism

Published by under autism,Neuroscience

The recent issue of Neuron has a series of articles providing more information about the genetics of autism spectrum disorder (ASD). ASD is characterized by decreased social ability as a core feature, with other clinical features being variable. It is also not a single disease or disorder, and not just because of the spectrum of clinical features. Like many clinical entities, there can be many underlying causes that result is similar-looking clinical effects.

While debate rages as to possible environmental triggers or even causes of ASD, researchers have been slowly building a picture of ASD as a complex genetic syndrome. Literally hundreds of genes have been potentially implicated. Many of the genes linked to ASD are involved with brain proteins or brain organization.

The recent studies in Neuron look specifically at families with a single child with ASD. In families with multiple children, or with a parent and child on the spectrum, the disorder is likely inherited. But what of families with only one child with ASD, and at least one child without, with no affected parent? Such a pattern can also be consistent with an inherited disorder, if it is recessive or X-linked. In a recessive disorder both parents can be unaffected carriers, and 25% of children will be affected – so having a single affected child is not unusual. However, ASD genes tend to be dominant, which means at least one parent should be affected along with at least 50% of children.

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16 responses so far

May 04 2011

Mark Geier’s License Suspended

I learned this morning that the state of Maryland has suspended the license to practice medicine of Mark Geier - elder of the father-son Geier team who have notoriously been treating children with autism with chemical castration.

This is very good news. It is heartening to occasionally see a state medical review board actually do their job and discipline physicians who are practicing abject quackery. I am only partly blaming state boards for their general lack-luster performance in this area. In many cases their hands are tied by state laws designed specifically to hamper their ability to discipline unscientific or substandard medical practices.

For further background on the Geier lupron protocol, here is a good article by David Gorski at Science-Based Medicine. He has been following the story closely.

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7 responses so far

Apr 06 2011

Disparities in Autism Diagnosis

Published by under autism

I have been following the literature on autism diagnosis both because of my general interest as a neurologist, but also because it is at the center of the vaccine-autism myth. There is no question that autism diagnoses have been on the increase over the last 20 years. There are some who assume that this increase in the number of diagnoses being made represents a true increase in the incidence of the disorder – hence an autism “epidemic”.

However, careful analysis reveals that the increase in diagnosis is largely explained (perhaps completely explained – but a small real increase cannot be ruled out) by increased awareness of autism and an expanded diagnosis. (See my earlier posts for a full explanation.)

A recent study sheds further light on this issue. The study was not addressing the broader question of the causes of the increase in autism diagnosis, but rather was focusing on socioeconomic disparities in diagnosis. The results, however, do lend support to the conclusion that the rising autism diagnoses was largely due to increased awareness, rather than a true increase.

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14 responses so far

Jan 27 2011

Some Nonsense from J.B. Handley

Published by under autism

The intellectual dishonesty, or such blinkered stupidity that it is indistinguishable from this, of the anti-vaccine crowd is always a spectacle. J.B. Handley is a prime example. He has made himself into an intellectual bully, and internet thug for the Age of Autism.

In a recent piece for this wretched hive of anti-vaccine propaganda, Handley write:

“It’s been asked and answered, vaccines don’t cause autism.”

This lie, it really drives me nuts. More, and I can say this and mean it, anyone who repeats this lie is immediately my enemy. I mean that, I really do, because there are just too many kids in the mix and this is just too important and if you are either intellectually too lazy or too dishonest to understand the science around vaccines and autism, then, well, you are my enemy. Sorry, it’s a hard knock life.

That captures his “Goodfellas” approach quite nicely. If you disagree with him – you are his enemy, the gloves are off, and anything is justified. To add irony to his thuggery, Handley himself is just too intellectually lazy, or (in my opinion) scientifically illiterate to “understand the science around vaccines and autism.” Yet he presumes to lecture those who have dedicated their lives to studying science, and in fact is willing to make them his enemy because they have the audacity to point out that his understanding of science is hopelessly flawed.

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13 responses so far

Jan 13 2011

Deer Criticizes Doctors for Defending Wakefield

Brian Deer is the investigative journalist who has spent years building a case that Andrew Wakefield’s original Lancet paper alleging a connection between the MMR vaccine and an autism-GI disorder syndrome was not only bad science, it was fraud motivated by greed. In part two of his BMJ series detailing the results of his investigation, Deer follows the money, showing that Wakefield stood to make millions from a monovalent replacement vaccine as well as testing for his proposed new GI disorder. For those interested in the details – read the BMJ article. In short Deer builds a convincing case that Wakefield created a fraudulent study designed to generate fear regarding the MMR vaccine that he would then exploit to make millions. Meanwhile he was also paid over a million dollars by trial lawyers to build a case against the MMR vaccine.

What I want to write about today is a recent blog post by Brian Deer in which he accuses the medical establishment of circling the wagons (at least initially) around Wakefield. Deer specifically cites Ben Goldacre and Paul Offit as examples of physicians who were unwilling to accuse Wakefield of fraud. Deer writes:

But a Philadelphia-based commentator was not impressed by the BMJ’s intervention. “It doesn’t matter that [Wakefield] was fraudulent,” Dr Paul Offit, a vaccine inventor and author in Pennsylvania, was quoted in the Philadelphia Inquirer the next day as saying. “It only matters that he was wrong.”

I wasn’t surprised. From his establishment vantage-point, this was the third time Dr Offit had popped up to opine on the issue. Twice previously he’d been quoted as saying that my findings were “irrelevant” (although he’d been happy enough to use them in his books). Science had spoken, his argument went. There was no link between the vaccine and autism. It was experts like him who should rule on this matter, he seemed to imply, not some oik reporter nailing the guilty men.

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24 responses so far

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