Autism and The Gut: Who Is The Real Culprit?

 

The first thing you think of when you hear the word “Autism” is a problem with someone’s head or more accurately, their brain. It doesn’t mean that is always the case though.


According to the World Health Organisation (WHO), the prevalence of Autism Spectrum Disorder among children is around 1 in 160. A worrying number.

When it comes to our brains, there is a fundamental and repetitive format as to how its cells connect and communicate with each other. The junction between one brain cell (also called a neuron) and the next one is called a synapse. This is where the magic happens. An electrical signal reaches the end of a neuron, leading to the release of molecules and that conveys a signal to the next neuron.

 

Around 100 billions of these guys are just doing their thing. Source: Flickr

 

 

The neurons in the land down under


Away from the brain and down to business. An often overlooked part of the nervous system is the one in our guts. A neuroscience professor used to rant about this last semester talking about how many neuroscience textbooks ignore it. He says the issue is providing an extremely watered-down version and failing to address the complexity.

It’s obviously significant though, because guess what takes over digestion after food slips into the stomach? A complete nervous system contained within us. The Enteric Nervous System, mainly responsible for a series of finely-controlled motor activities that manipulate food.

 

Activity here might also manifest as a set of terrifying sounds after finishing that succulent chinese meal. Source: Flickr.

 

The ENS contains neurons just like the brain does and they are arranged in specific ways to facilitate the previously mentioned movements. However, the principles remain the same.

 

A quick rundown on those principles

Don’t forget about the molecules I told you about before, because the way they start a signal may be disrupted in conditions like Autism.

Such molecules are called Neurotransmitters. They work by binding to receptors on a neuron when released into the synapse. The brain can perform a range of actions through this process. For instance, certain neurotransmitters can bind to a receptor and increase the excitability of that neuron while others can have an opposite, inhibitory effect. All these receptors are there because they are bound to the cell surface by specific proteins.

Neuroligins are a group of proteins doing exactly that. A mutation in Neuroligin-3 has been linked to autistic-like behaviours in mice. At a molecular level, amino acids swap positions in the protein, changing its whole function.

 

Is Autism simply a result of our complex nature?

Not necessarily. It is absolutely mind-blowing as to how much we have in common with other species.

An “autistic” mouse doesn’t have proper social interactions with other mice and often engages in repetitive activities, just like children on the autism spectrum do. Interestingly, drugs used to reduce aggressive behaviour in some autistic children yield a similar result in mice.

 

Rispiridone, a typical antipsychotic used for Autism as well as other brain disorders. Source: Flickr.

 

It’s obvious we have tons of information at our fingertips, but what do we make of it? Does Autism start in the gut and travel up to the brain? Or is it the other way around? Current research is wading through such questions in hope for some closure for all of us out there.

 


6 Responses to “Autism and The Gut: Who Is The Real Culprit?”

  1. aali2 says:

    Thank you for your comment Jamie. The differences are huge indeed, but the mere fact that a rat can be autistic too is crazy.
    Let’s just hope for amazing stuff in the future 🙂

  2. Jamie Liew says:

    Hey, great article! It was really interesting – I loved how you explained the enteric nervous system, I hadn’t considered certain aspects of its similarities with the brain before. I’m hoping that more research will be done in the similarities between humans and mice though because as complex as both are, there are marked differences between the two.. and obvious cases aside, what might not work on mice, may perhaps work on humans?

  3. aali2 says:

    Thanks for the comment iwallace! The unconventional approaches might reveal the answer in the end, we’ll never know!

  4. iwallace says:

    Great article. The enteric nervous system and mental health are a keen interest of mine. It’s amazing to explore this growing area of science and learn that perhaps traditional views of conditions including autism, depression and anxiety may have origins that we never imagined!

  5. aali2 says:

    Thank you for your comment Yi! Also thanks for pointing out the difference in numbers. The WHO website states that averages vary from one study to another, they probably reported the ones in the lower end.
    Can’t believe it actually slipped my mind! Thanks for the headsup.

  6. Yi says:

    Great article.
    Sorry to point out that the latest prevalence of ASD is up to 1 in 68 (CDC, 2012) and about 4 times more common among boys than girls.
    Just to be more precise, not all the cells in the brain are neurons. There are glial cells surrounding neurons.
    Thanks.