Category: Autism

“…children worldwide are being exposed to unrecognised toxic chemicals that are silently eroding intelligence, disrupting behaviours, truncating future achievements, and damaging societies…”

The rise in disorders like autism, ADHD and dyslexia could be linked to the industrial use of neurotoxic chemicals, according to new research published in The Lancet (Grandjean & Landrigan, 2014).

The epidemiologists have identified six chemicals that could have negative effects on children’s development.

This is on top of a previous report in 2006 which listed five potentially dangerous chemicals.

The six chemicals include fluoride, manganese, a solvent called tetrachloroethylene, DDT (a pesticide) and a flame retardant containing polybrominated diphenyl ethers.

Author Philippe Grandjean, from the Harvard School of Public Health, explained:

“The greatest concern is the large numbers of children who are affected by toxic damage to brain development in the absence of a formal diagnosis. They suffer reduced attention span, delayed development, and poor school performance. Industrial chemicals are now emerging as likely causes.”

The researchers identify studies providing evidence for connections between six chemicals and problems in children’s psychological development, including:

• Manganese has been associated with reduced intellectual function, reduced achievement in mathematics and increased hyperactivity.
• Flouride at higher levels in drinking water has been associated with seven point decrements in IQ.
• Pesticides like DDT, which are banned in richer countries, are still used elsewhere and have been associated with neurodevelopmental disorders.

These substances have been added to a growing list of chemicals which are well-known neurotoxins, like lead and methylmercury.

The authors suspect there may be many more chemicals in regular industrial use which may be damaging to children’s developing brains.

These include Phthalates and bisphenol A, which are used in plastics and cosmetics and air pollutants like carbon monoxide.

For example, one study of pollution in California has linked pollution from car exhausts to higher rates of autism spectrum disorders (Volk et al., 2013).

Very few of these potentially dangerous chemicals are regulated simply because little effort has been made to look at the dangers and the very high standards of proof that are required.

The authors argue that:

“The presumption that new chemicals and technologies are safe until proven otherwise is a fundamental problem. Classic examples of new chemicals that were introduced because they conveyed certain benefits, but were later shown to cause great harm, include several neurotoxicants, asbestos, thalidomide, diethylstilboestrol, and the chlorofluorocarbons.” (Grandjean & Landrigan, 2014).

The authors say that in order to protect children’s brains–which are highly sensitive–a new agency should be established to screen and test new chemicals used in industrial processes.

They end on a worrying note:

“…the total number of neurotoxic substances now recognised almost certainly represents an underestimate of the true number of developmental neurotoxicants that have been released into the global environment. Our very great concern is that children worldwide are being exposed to unrecognised toxic chemicals that are silently eroding intelligence, disrupting behaviours, truncating future achievements, and damaging societies, perhaps most seriously in developing countries.” (Grandjean & Landrigan, 2014).

Image credit: Josh Pesavento

New research ‘gives autism’ to mice, then cures it with probiotic therapy.

One of the many curious things about autism is that it is often accompanied by gastrointestinal issues, despite it being primarily thought of as a brain disorder.

For example, many people with autism also have inflammatory bowel disease and other gastrointestinal problems like constipation and abdominal cramps.

This has led scientists to wonder how much the gut might have to do with the brain.

A new study, published in the journal Cell, tests out this link in autism between the gut and the brain in a mouse model (Hsiao et al., 2013).

Curing a leaky gut

The Caltech study created mice with autistic behaviours by exposing them to a virus-like structure which provokes an immune response.

Like humans with autism, the mice also developed intestinal problems. They had ‘leaky guts’: material was allowed to pass from their intestines into their blood stream.

The question is: could they fix the problem?

One experimental treatment for autism that has had some success is the use of probiotic therapy.

So the researchers then treated the mice with Bacteroides fragilis, which has been used in probiotic therapy.

After the treatment, the mice’s leaky guts were fixed.

Not only that, but their behaviour also changed. They were much less likely to engage in repetitive digging behaviours. This is a good sign since repetitive behaviours are a common feature of autism in humans.

They also displayed reduced anxiety and were more likely to communicate with other mice–similarly, communication difficulties are a core feature of autism in humans.

Mind-altering microbes

The lead author of the study, Elaine Hsiao, explained:

“The B. fragilis treatment alleviates GI problems in the mouse model and also improves some of the main behavioral symptoms. This suggests that GI problems could contribute to particular symptoms in neurodevelopmental disorders.”

The scientists think that the therapy works because it stops certain metabolites leaking into the bloodstream, which then affect the brain and behaviour.

After this success, their next step will be to try the therapy on humans. However, another of the study’s authors, Professor Sarkis K. Mazmanian, said:

“Autism is such a heterogeneous disorder that the ratio between genetic and environmental contributions could be different in each individual. Even if B. fragilis ameliorates some of the symptoms associated with autism, I would be surprised if it’s a universal therapy–it probably won’t work for every single case.”

Nevertheless, it’s a fascinating finding about what continues to prove a baffling disorder.

Here is Elaine Hsiao talking about mind-altering microbes at a TEDx event at Caltech (link):

→ Now read on: Autism: 10 Quick Facts You Should Know

Image credit: Elaine Hsiao

Autism: what are the numbers, the symptoms, the cause, the genetics and the cure?

Despite all that scientists have learnt about autism over the years, unfortunately the condition remains extremely mysterious.

There are so many symptoms, so many possible causes, so many possible treatments, it can be very confusing.

So here are 10 quick facts about autism to get you started.

(My apologies in advance that so many of these ‘facts’ are so woolly, but the nature of the condition is very hard for everyone, specialists included, to grasp.)

1. How many?

There are around 70 million people around the world who are autistic.

Prevalence in the US is around 1 in 100 children, maybe more.

Males are about four times more likely to have it than females.

2. The symptoms

It’s way more than just avoiding eye contact: autism is a combination of poor social, cognitive and adaptive skills.

Typical problems include language impairment, repetitive behaviours, social problems, sleep disorders, allergic reactions, seizures and abnormal behaviour in general.

Some combination of these is normally noticeable between six months and two-years-old.

But this list is still deficient: if there is a problem that a child can suffer from, then at one time or other it has been associated with autism.

That’s how confusing the condition is.

3. Is there a cure?

Autism is usually considered a lifelong condition. There is, as yet, no cure.

However, somewhere between 3% and 25% of children may lose their autistic diagnosis over the years (Helt et al., 2008).

Those most likely to recover have high intelligence, reasonably good language skills and motor development.

4. One-quarter of children are non-verbal

Set against the positive finding that some may recover, for many others the prognosis is much darker.

For example, about one-quarter of autistic children are mostly or completely non-verbal.

Perhaps as many as half of those with autism do not develop strong enough linguistic skills to get by in everyday life.

Sometimes these problems continue into adulthood.

5. It’s a spectrum

From (3) and (4), you’ll see there’s huge variability in the disorder.

That’s why it’s now known as an autism spectrum–a very big spectrum.

The ‘spectrum’ includes Asperger’s syndrome, childhood disintegrative disorder and a host of other alternative names and classifications.

6. What causes it?

Again, the real answer is that we just don’t know.

Things that have been implicated to varying degrees include: parents’ genes, the age of parents at birth, a deficient mirror-neuron systems in the brain, the ‘extreme male brain’ and so on.

None of these are definitive, though.

7. Incredible genetic complexity

There are literally hundreds of different genes that have been implicated to a greater or lesser extent (mostly to a lesser extent) in the development of autism.

As of writing, the autism database currently lists 573 genes thought to be related to autism.

Needless to say, that makes it exceedingly complex to study.

8. Cortical under-connectivity

You might be starting to think: is there anything at all you can definitively tell me about autism?

Well, one relatively new theory about autism–that it results from cortical under-connectivity–is promising.

In other words: in autism, the various parts of the brain do not talk to each other as efficiently and effectively as in a typical brain. The individual skills are there, but they are not fully integrated into a whole.

Once again, though, this is only a theory.

9. Savant syndrome

A small proportion of those with autism, around 10%, have savant syndrome.

These people can have extraordinary abilities in some limited areas, such as highly advanced mathematical or musical skills, improved visual acuity and visuospatial abilities.

Among people with autism, though, these are the exception rather than the rule.

10. What’s the treatment?

All sorts of treatments for autism have been tried, both chemical and behavioural.

Among the chemical treatments, various drugs with frightening names like Risperidone and Ziprasidone have been found to help somewhat; but these do not address the core autistic problems of social and communicative dysfunction.

Amongst behavioural approaches the most useful seem to involve play, those which focus on motor skills and the use of picture exchange for communication (McCleery et al., 2013).

Unfortunately most studies in this area are badly designed so we don’t have strong scientific evidence of what works.

→ This article is partly based on the excellent review of 1,300 different studies of autism by Hughes (2009).

Image credit: hepingting

Like alexithymia, those with autism spectrum disorders (ASDs) are also known to have problems processing emotional information. This may at least partially account for some core features of autistic behaviour: especially problems in social interactions. After all, ordinary social interactions contain considerable emotional components. This post looks at studies which have examined how those with ASDs may have deficits in the automatic processing of emotions.

Continue reading “Emotion Processing in Autism Spectrum Disorders”

Recently I’ve been looking at the causes of emotions as suggested by appraisal theory. Very briefly, this theory posits that our emotions are generated through an evaluation of particular types of information that are relevant to us. But what does ‘evaluation’ mean and how does this occur?

Continue reading “A Process Model of Appraisal”

Having now seen the excellent documentary on the autistic savant, Daniel Tammet, and noting the subject’s popularity, I’ve done a little Googling to get some more information for you…

This is the BBC News report of Daniel Tammet’s attempt at the British and European record for reciting pi. He is able to remember 22,511 decimal places of pi without using any special memory techniques.

‘The Savant Syndrome’ provides more background information on autistic savants. The article is by Dr. Darold Treffert who is widely published on this subject and was a consultant to the movie Rain Man. More on other autistic savants at Wikipedia.

New York Times review of the documentary.
Science Channel ‘Brainman’ site [contains extra video not in programme]

“Daniel Tammet is an autistic savant. He can perform mind-boggling mathematical calculations at breakneck speeds. But unlike other savants, who can perform similar feats, Tammet can describe how he does it. He speaks seven languages and is even devising his own language. Now scientists are asking whether his exceptional abilities are the key to unlock the secrets of autism.”

→ From The Guardian