The Neuroscience of Autism Spectrum Disorder: Insula Cortex

In this chapter of the Neuroscience of Autism Spectrum Disorder series, I want to talk about changes in a brain region called the insula cortex. And just like that we have moved to our first structure in the cortex. The cortex is the thin layer on the outer surface of the brain. And even though the cortex is only about an inch thick, it is mostly this region that sets humans apart from other animals. The cortex is what allows for really complex intelligence, and not surprisingly its functions are very complex and mysterious. In humans, the cortex has grown so large that it won’t even fit on the top of our brains anymore, so instead it is wrinkled up. That’s why when you see a picture of a human brain you see a wrinkly mess. The bigger the cortex, the more wrinkles there are.

But even though all we can see when we look at a human brain is lots and lots of cortex regions, you still can’t see the insula cortex. That’s because it folds inwardly and gets covered up by the other lobes. The only way to see it is to cut a brain in half and look at the folds from the inside, as shown in the picture below. In this picture the insula cortex has been colored green, brown, and blue, and you can see how it has folded inside the brain whereas the rest of the cortex wrinkles up on the surface.

Human_brain_frontal_(coronal)_section_description2

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The neuroscience of Autism Spectrum Disorder: Cerebellum

On a cold Christmas day 1989, in a cramped room in Romania, the verdict of the Court-Martial was handed down. General Secretary Nicolae Ceausescu, the man who had ruled Romania with a tyrant’s fist for the last 20 years, was sentenced to death for committing genocide. Like so many other Soviet nations, the brutal Romanian communist dictatorship that had murdered tens of thousands of people and left many millions more in terrible poverty was suddenly over. Photos, videos and stories from journalists began pouring out to the rest of the world for the first time since the end of World War II, and the contents of those images were far more terrible and shocking than anyone could have known. Poverty and starvation were everywhere since Ceausescu had ordered the food, medicine, and other basic supplies be sold to pay off government debt. Worst of all came the pictures of the children. News story after news story broke showing orphanages packed full of starving, dirty, sick children. Ceausescu had made it illegal to stop having children in an effort to boost the nation’s population.

The rest of the world opened their arms, and the stream of refugee children came pouring out of Romania. To the United States, Canada, United Kingdom and many other wealthy nations they were sent, into the arms of empathetic parents that couldn’t see children in such need without opening their hearts and lives to them. But the battle to save these children was only just beginning.

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The neuroscience of Autism Spectrum Disorder: Amygdala

The last few posts in this series have been laying down a groundwork by establishing what Autism Spectrum Disorder is, and how it is caused. With that information behind us, we can get into the fun stuff. Let’s take a look inside an Autistic brain.

There are multiple brain regions that scientists have found differences in when studying Autism Spectrum Disorders. To discuss all of them in one post would probably make it too long to read in a single sitting, so I’ll break it up into different sections. This post, we will cover the autistic amygdala.

Amygdala

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Could Autism genes be beneficial?

Last time, we discussed what was known about the causes of Autism Spectrum Disorder. The evidence from twin studies showed that if you share genes with someone who has Autism, chances are really high that you will also have Autism. So the disorder has a strong genetic link. We also saw that there is not one “Autism gene” responsible for the disorder, but many genes that are associated with increased risk of Autism. In fact, it looks like there are probably hundreds of genes, each one slightly increasing the risk that you will have Autism.

Not only are there hundreds of genes that increase the risk of developing Autism, but in fact most of those genes are commonly found in our population. That means that if someone took a sample of your DNA, it is almost guaranteed that they would discover that you have dozens of these Autism genes. So if each of us has dozens of Autism genes but did not develop an Autism Spectrum Disorder when we were kids, what are those genes doing? Because Autism is such a devastating disorder, it is tempting for us to think of those genes we have as bad. But for those of us who inherited lots of Autism genes but not enough to develop the disorder, could those genes be giving us some benefits?

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What twins can teach us about the causes of Autism

In my first post of this series, I made the case that vaccines do not cause autism. If it isn’t vaccines though, what exactly is causing Autism?

We’ve established that Autism is a condition in which the brain processes emotional and social information differently than normal brains. The question is what is causing the brain to get wired in this different way? Autism Spectrum Disorder presents in early childhood, which also happens to be the age when the brain is going through one of the biggest developmental changes. This suggests that something is happening in these young brains that changes the way they develop and therefore changes how they process information. But what?

This is still an open question, and scientists are working hard to nail down what the causes of Autism are. Which is why it is such a tragedy that so much money, time and resources are getting diverted into studies double-checking (now triple- or quadruple-checking)  that vaccines are not the cause. But just because this is an open question doesn’t mean we have no idea what causes Autism. Recent studies have shown strong evidence that there are genetic and environmental factors that increase a child’s likelihood of developing an Autism Spectrum Disorder.

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Autism, Autism Spectrum Disorder, Asperger’s Syndrome… What are they, and what’s the difference?

What’s in a name?

Autism Spectrum Disorder has several labels, and these labels have shifted over the years as scientists’ understanding of the disease has improved. Psychologists keep a giant book called the Diagnostic and Statistical Manual that describes in great detail every single recognized psychological disorder. About once every 15 years, a new version of this book is put out to update doctors and scientists about what has been learned. This can result in some confusion. Everyone gets comfortable with the titles that have been given for each disorder and then suddenly a new Diagnostic and Statistical Manual gets published that says everyone needs to start calling it something else.

This is exactly what has happened with Autism. In the previous version of the Diagnostic and Statistical Manual, there were 5 disorders: Autistic Disorder, Rett Syndrome, Childhood Disintegrative Disorder, Asperger’s Disorder, and Pervasive Developmental Disorder Not Otherwise Specified. Each of these disorders was considered to be a part of a family of disorders called Autism Spectrum Disorders. But then came 2013, and a new version of the Diagnostic and Statistical Manual was released. It was decided that having five different disorders with overlapping symptoms that were all frequently called autism was all just a little bit too confusing. So now all of these disorders have been combined into just one Autism Spectrum Disorder.

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Autism Spectrum Disorders are caused by vaccines, right?

With so much news attention lately on the growing number of parents who have become concerned that vaccinations might be linked with autism, I thought it would be fun to spend a few posts on what is known about the neuroscience of autism.

For my first post on this topic, I am going to start with the reason this topic is in the news so much; the belief that vaccines may cause or increase the risk of autism. This is the least interesting aspect of this topic for me because the scientific answer is resoundingly “NO!” and also because there are so many fantastic blogs and articles discussing this (see here, here, and here).  I have nothing to add to what those experts have already said, but because there is so much misinformation and skepticism out there I feel obligated to start any conversation about autism with a discussion on what is known about the link between autism and vaccines. So, here we go. To start, let me unequivocally state that there is no scientific evidence to suggest that receiving vaccinations increases the likelihood of acquiring an autism spectrum disorder. The controversy has mostly come from one paper published in The Lancet which did suggest a possible link in 1998, but a slew of follow-up papers could not replicate those findings. These many follow-up papers have now examined autism rates in over a million children and compared them to their vaccination records, and have found no effect of vaccination. Compare that to the Lancet paper that started this mess, which looked at only 12 children. It turns out there are more problems with that Lancet paper than just a low number of patients; it appears the researcher in question did not randomly sample to get those 12 children and in fact may have selected them in a biased manner. It gets even worse; the researcher’s funding may have come in part by lawyers who were carrying out lawsuits against vaccine manufacturers. Because of these and other problems the Lancet has retracted that study.

There is zero credible evidence that vaccines cause autism. There are now many credible studies suggesting vaccines do not increase the risk of autism.

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