- Created by: sarah_mocha
- Created on: 15-05-17 20:37
What is autism?
Autism is a neurodevelopmental disorder that's characterised by impaired social interaction, verbal and non-verbal communication, and restricted and repetitive behaviour. It is caused by a combination of genetic and environmental factors. It is a long-term condition and generally manifests in the first 3 years of life. Autism affects information processing in the brain by altering how nerve cells and their synapses connect and organise.
The NHS estimated that the overall prevalence of autism among adults aged 18 years and over in the UK was 1.1%. Boys are at higher risk for autism than girls. The sex ratio averages 4:1.
Symptoms in children include:
- delayed and poor speech development
- rejecting cuddles initiated by a parent or carer
- little interest in interacting with other people, including children of a similar age
- avoiding eye contact
- not being aware of other's personal space, or being unusually intolerant of people entering their own personal space
Triad of impairment
The three main areas of difficulty which all people with autism share are sometimes known at the 'triad of impairments', as first described by Lorna Wing. As well as this, they identified a repetitive stereotyped pattern of activites. The triad is comprised of:
Difficulty with social communication: there is a delay in/lack of, the development of spoken language. There is a stereotyped, idiosyncratic and repetitive use of language. Also, there is a lack of varied, spontaneous make-believe play or social imitative play.
Difficulty with social interaction: this includes a lack of nonverbal behaviours, social/emotional reciprocity, and spontaneous seeking to share enjoyment.
Difficulty with social imagination: difficulties in: imagining the world from someone else's perspective, interpreting others thoughts and feelings, understanding the concept of danger, engaging in interpersonal/imaginative play, and preparing for change and planning for the future.
Theory of mind
Theory of mind is also known as 'mentalising' or 'perspective-taking'. It is the ability to attribute mental states - beliefs, intents, desires, pretending, knowledge, etc - to oneself and others and to understand that others have beliefs, desires, intentions, and perspectives that are different from one's own. It usually develops in typically developing children at age 3-4 years.
Simon Baron-Cohen, Alan M Leslie and Uta Frith suggested that children with autism do not employ a theory of mind, and they have particular difficulties with tasks requiring the child to understand another person's beliefs. Many individuals classified as having autism have severe difficulty assigning mental states to others, and they seem to lack theory of mind capabilities.
Baron-Cohen (1985): compared children with autism spectrum disorder, down syndrome, and typically developing children of 3-4 years. Results showed 86% of children with DS passed, 85% of typically developing children passed, but only 20% of children with ASD passed.
Extreme male brain
Males are more likely than females to have autism, Asperger's syndrome, or any other type of ASD. In the first clinical account of autism in 1943, psychiatrist Leo Kanner noted that boys with the condition outnumbered girls by a ratio of 4 to 1. Recent studies continue to show that the ratio of boys to girls with autism is about 4-5:1.
Simon Baron-Cohen proposed the extreme male brain theory of autism, which attempts to explain the remarkable similarities between traits generally associated with human "maleness" and traits associated with the autism spectrum. Typically developing males tend to show strengths in mathematical and spatial reasoning. Compared with typically developing females, males tend to be at a higher risk for language impairment and at a disadvantage on social-judgment tasks, measures of empathy and cooperation, and imaginary play during childhood. Many of the traits associated with ASDs could be thought of as an extreme profile of "typical male" strengths and challenges.
Baron-Cohen and colleagues came up with a model for this idea which divides the way the brain works intwo 2 major dimensions: systemising and empathising
Systemising and empathising
Systemising is defined as "the drive to analyse or construct systems" that "follow rules". It also involves being able to predict the behaviour of a system. Males are, on average, more skilled at systemising than females are.
Empathising is defined as "the drive to identify another person's emotions and thoughts, and to respond to these with appropriate emotion". It also involves being able to predict the behaviour of these people. Females are, on average, more skilled at empathising than males are.
The extreme male brain theory views people on the ASD as hyper-systemisers: people who are extremely interested in and engaged with rule-bound non-human systems, whatever their level of functioning.
Families and the educational system are the main resources for treatment. Intensive, sustained special education programs and behaviour therapy early in life can help children acquire self-care, social, and job skills, and often improve functioning and decrease symptoms severity and maladaptive behaviours.
Available approaches include: applied behaviour analysis (ABA), structured teaching, speech and language therapy, social skills therapy, and occupational therapy.
Medication can be used to treat ASD symptoms that interfere with integrating a child into home or school when behavioural treatment fails. More than half of US children diagnosed with ASD are prescribed psychoactive drugs or anticonvulsants, with the most common drug classes being antidepressants, stimulants, antipsychotics.
Autism: biological factors
Autism has a strong genetic basis, although the genetics of autism are complex and it's unclear whether ASD is explained more by rare mutations or by rare multigene interactions of common genetic variants. Many genes have been associated with autism through sequencing the genomes of affected individuals and their parents.
Studies of twins suggest that heritability is 0.7 for autism and as high as 0.9 for ASD, and siblings of those with autism are about 25 times more likely to be autistic than the general population. The large number of autistic individuals with unaffected family members may result from spontaneous structural variation - such as deletions, duplications, or inversions in genetic material during meiosis.
EEG recordings of autistic patients showed a dysfunctional mirror neuron system: their mirror neurons respond only to what they do and not to the doings of others. The human mirror neuron system is thought to be involved not only in the execution and observation of movement, but also in higher cognitive processes - language, or being able to imitate and learn from others' actions, or decode their intentions and empathise with their pain. As autism is characterised by these defecits, it was previously suggested a dysfunctional mirror neuron system may explain symptoms.
One study concluded that they found evidence for a link between the MMR vaccination and the development of autism. However, the study was was based on only 12 children, and was later found to have fabricated results.