Brain Science of Aspergers and Autism Pt. 2: Anger and emotion

It is generally accepted that in Aspergers Syndrome and Autism that there is some abnormality in a primitive area of the brain called the amygdala. The name “amygdala” means almond, and there are two almond shaped structures buried deep within the medial temporal lobe. These form part of the “limbic system”, which is responsible for generating and modulating emotions, and laying down long term memories. The role of the amygdala is to coordinate information from different parts of the brain and generate the emotion.

Emotions are a response to bodily changes e.g. feeling hot, tense, sweating, or going red. The amygdala receives sensory information about a situation and the bodily changes from the nervous system, and everyday experience confirms or dismisses the threat accordingly. It is far better to interpret a stick as a snake and respond accordingly only to find out it was really a stick, than for your brain to think about it and get bitten before you realise what is going on.

According to neuroscientist Eric Kandel, emotion, such as fear and anger, has two components, conscious and unconscious. The amygdala receives information from both unconscious and conscious pathways when the brain perceives a threat.

The unconscious component of emotion is the operation of the nervous system. The stimulus is then analysed and an area of the brain called the hypothalamus regulates the emotion.

The conscious component of emotion involves evaluative functions of the cerebral cortex (the area responsible for planning, attention, language and reasoning), and the hippocampus, which is responsible for long term memories and the memory of emotion.

Central to both is the amygdala. According to Kandel, the amygdala is thought to coordinate the conscious experience of feeling and the bodily expression of emotion, particularly fear. It is also the area responsible for triggering the “fight or flight” response.

It seems that in the brain of someone with Aspergers or Autism that the amygdala is triggered on the unconscious component of emotion. It is possible that the brain misinterprets a stimulus as threatening, possibly due to Merzenich’s undifferentiated brain maps. When the person is in this state, logic and reasoning don’t work, and they are not necessarily aware of why they feel so angry or afraid. It appears that something in this system is not working correctly. It is understood that they have an abnormality in their amygdala, but there may also be other factors at work here, such as malfunctions in the pathways to the parts of the brain that analyse the emotion.

Cognitive Behavioural Therapy is often recommended to assist a person with Aspergers or Autism in the controlling of their emotions. Often the therapist will use a visual aid such as a “thermometer” to allow the person to recognise the bodily changes described above, before the amygdala sends the message to release the hormones associated with the fight or flight reflex. It also allows them to consciously analyse their emotions. Tony Attwood has a CBT program that he has developed; further information can be found here.

Once the emotion is triggered, it is impossible to reason with the person with Aspergers, so it is best to leave them to safely calm down, or to distract them. Tony Attwood advises using their special interest as an effective distraction, or maybe giving them a sensory toy to play with.

It seems that traditional methods of meditation and relaxation do not work with someone with Aspergers. Tony Attwood notes that they prefer to be active or physical or to do something repetitive, or even listen to music of their choosing, probably very loudly and over and over again.

References: In search of Memory by Eric Kandel, The Complete Guide to Asperger’s Syndrome by Tony Attwood, The Emotional Brain by Joseph Le Doux

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No single cause for ASD?

Francesca Happé, Angelica Ronald and Robert Plomin at the Institute of Psychiatry, Kings College London, believe that it is time to give up on the search for a single cause of Autism Spectrum Disorder, that many genes could be responsible for separate traits on the autism spectrum. Read their paper here

Autism Spectrum Disorder and Fragile X link?

Neurorocker at en.wikipedia

 

When I started to really dig into the genes behind Aspergers and Autism, it seemed that it isn’t as clear cut as I initially thought. After researching the brain science of Fragile X syndrome (and the FMR1 gene) to establish how it could cause Autism and Aspergers, I discovered that that there isn’t just one gene that causes ASD. It seems there may be a range of genes, all of which seem to have similar effects on the developing brain.

In this post I shall discuss the FMR1 gene that causes Fragile X syndrome and its link to Autism.  Fragile X Syndrome is so called because a small section of the genetic code is “repeated on a fragile area of the X chromosome” (source PubMed Health)

According to the National Fragile X Foundation:

“FXS is the most common known cause of autism or “autistic-like” behaviors [sic]”

“Fragile X syndrome can cause a child to have autism or an Autism Spectrum Disorder (ASD) though not all children with fragile X syndrome have autism or an ASD.

  • FACT: For between 2% and 6% of all children diagnosed with autism, the cause is the Fragile X gene mutation.
  • FACT: Approximately one-third of all children diagnosed with fragile X syndrome also have some degree of autism.
  • FACT: Fragile X syndrome is the most common known single gene cause of autism.”

The A.D.A.M. Medical Encyclopedia notes that the symptoms of Fragile X are very similar to those with Autism:

  • “Delay in crawling, walking, or twisting
  • Hand clapping or hand biting
  • Hyperactive or impulsive behavior
  • Mental retardation
  • Speech and language delay
  • Tendency to avoid eye contact”

The reason Fragile X caught my eye is that one of the most common symptoms or signs of Fragile X is the hypersensitivity to sensory stimuli, as outlined by an article in Science Daily:

“New research provides insight into why fragile X syndrome, the most common known cause of autism and mental retardation, is associated with an extreme hypersensitivity to sounds, touch, smells, and visual stimuli that causes sensory overload and results in social withdrawal, hyperarousal, and anxiety. The study, published by Cell Press in the February 11 issue of the journal Neuron, uncovers a previously unknown developmental delay in a critical brain circuit that processes sensory information in a mouse model of fragile X syndrome.”

This is consistent with my view that the majority of symptoms associated with Autism and Aspergers are caused by sensory overload. In response to this article the Shared Attention website notes that: “This seems to support so-called experimental therapies (e.g. sensory integration) that theorize that plasticity in sensory processing can afford lasting positive changes in neurological function and behavioral outcomes. In other words, by using natural interests of the child to harness their attention and engagement, it may be possible to use purposefully engineered activities to modify and naturalize those pathways”.

And it seems that treatment for a child with Fragile X is similar to those with Autism and Aspergers. Source: Medicine.net:

  • Know the learning style of the individual.
  • Develop a consistent daily schedule or routine.
  • Use visual signs (pictures, sign language, logos, words) and concrete examples or materials to present ideas, concepts, steps, etc.
  • Prepare the individual for any changes in routine by explaining them ahead of time, possibly using visual signs.
  • Include functional goals with academic goals; for instance, teaching the individual the names of different pieces of clothing as well as how to dress him/herself.
  • Provide opportunities for the child to be active and move around.
  • Use computers and interactive educational software.
  • Provide a quiet place where the child can retreat and regroup.

So how does the Fragile X gene lead to symptoms similar to Autism?

This from the A.D.A.M. Medical Encyclopedia.

“Normally, the FMR1 gene makes a protein needed for your brain to grow properly. A defect in this gene makes your body produce too little of the protein, or none at all.” The link between the FMR1 gene and the hypersensitivity displayed in Aspergers and Autism has been established (see academic paper)  . The nerve cells in the brain initially grow extra branches, which could explain the hypersensitivity to various sensory stimuli. This could lead to the premature turning off of the “critical period” as discovered by Merzenich. The nerve cells eventually “prune” the branches so that the nerve cells appear normal, but at this stage it could already be too late, as the brain is left with the “undifferentiated brain maps” discovered by Merzenich.

According to the A.D.A.M. Medical Encyclopedia:

“Boys and girls can both be affected, but because boys have only one X chromosome, a single fragile X is likely to affect them more severely. You can have Fragile X syndrome even if your parents do not have it.

Fragile X syndrome can be a cause of autism or related disorders, although not all children with fragile X syndrome have these conditions.”

The symptoms are more likely to be pronounced in boys, girls may only exhibit behaviours such as shyness.

But the FMR1 gene cannot be the only cause of ASD. The main issue with this as an umbrella answer to ASD is that males with Fragile X cannot pass it onto their sons, due to the fact that they only transmit the Y chromosome, and not the X. (source: Autism Help)  But it seems that many boys with Aspergers and Autism have a father who also has it. In addition the IQ of a person with Fragile X Syndrome is highly likely to be below average, although this is not always true for girls. Although the research in this area may be slightly inaccurate, as medicine.net points out:

“Attention disorders, hyperactivity, anxiety, and language processing problems can interfere with test-taking skills and learning. Because many people with Fragile X have these problems, a person with Fragile X may have more capabilities than his or her IQ score suggests”

So the search for the common cause continues…

Academic Papers on Fragile X:

http://www.fragilex.org/pdf/kaufmann-et-al_autismandfragileX.pdf

http://www.ncbi.nlm.nih.gov/pubmed/19441123