- Created by: embarry27
- Created on: 07-12-19 13:08
History of Autism
- Kanner published his initial report in 1943 and his initial description of the disorder marks the first recognition of autism as a distinct developmental disorder.
- History of autism includes Bettleheim's (1949) 'refrigerator mothers' ~ ambivalent, witholding mothers, whose inadequate attachments to their children drove them into their inner isolated worlds.
- Kanner noted a central characteristic of ASD "the inability to relate themselves in an ordinary way to people and situations'
- For many years, in the absence of 'autism' in the DSM, many children were incorrectly diagnosed with childohood schizophrenia.
- Autism wasn't recognised in the DSM until the DSM-III, published in 1980.
- Boys outnumber girls 4 to 1 but for low cognitive functioning autism it is 2 to 1, and for high functioning, it is 15 to 1.
Facts about Autism
- Data from the CDC (2000) found that the average age children were diagnosed with autism was 4 years, but that the average diagnosis was not until 13 months later. Evidence suggests this is coming down. The majority of diagnoses are now between the ages of 2-3.5, but autistic behaviours should be present before the age of 3.
- Prevalence of autism spectrum disorder is about 1 in 100 (Baron-Cohen, 2008).
- Autism is best described as a spectrum.
- Researchers commonly distinguish between 6 major subgroups on the autism spectrum (Baron-Cohen, 2008) and these are differentiated by cognitive ability.
- Asperger's syndrome is at the higher end (individuals wih normal intelligence who did not demonstrate signficant delays in early languge acquistion) (Howlin, 1997)
- Approximately 2./3 of children with autism have an IQ score in the range that identifies them as having learning difficulties (IQ of 70 or less)
- Core diagnostic features of autism are currently defined at the level of behaviour (these are social, affective and cognitive), so clinical psychologists are important.
Triad of Impairments
- Kanner was the first to note social disconnect was accompanied by communication oddities and preference for restricted and repetitive behaviours (Benaron, 2008)
- In 1979, Wing and Gould proposed that autistic children have difficulties in three areas, now known as the 'triad of impairments'
- Impairments in social orienting
- Three groups of children: (info from Buron et al, 2014)
- the aloof child: actively avoids social interactions
- the passive child: can tolerate social interaction with encouragement and can initiate social contact, but primarily to achieve access to something they want
- 'active but odd' child: actively wants to interact with others (usually adults) but despite motivation to socialise, is odd due to a lack of social understanding and range of social abilities. Might not use conventional greetings and might continue as if they have a limited social script or repertoire of social behaviour, such as a reliance on repetitive questions.
- Eye-tracking technology is providing new insights into the nature of impairments in social ineraction as indicated by unusual visual beahaviours (one of the specific behaviours is either extremely little eye contact, or staring for prolonged periods)
- Dalton et al. (2005) - combined eye tracking with fMRI, finding diminished eye region fixation in subjects with autism. fMRI revealed that the response of the fusiform gyrus (FG) to faces was also diminished in subjects with autism.
- elective mutism (no desire to communicate despite being able to)
- echolalic speech (repeat other's words or phrases)
- pronoun reversal (confuse I and you)
- lack of prosody (e.g. fall and rise in voice to communicate emotions)
- lack of gesture communication (e.g. nod head to show approaval)
- difficulty at 'reading faces'
- A minority of children (usually diagnosed with AS) do not show any significant delays in the onset of language milestone. Most with autism however, begin to speak late and develop speech at a significantly slower rate than others (Le Couteur et al, 1989).
- Various retrospective studies suggest that by the 2nd year of life, communication of most children with autism is different from other children (Dahlgren et al, 1989).
- In the preschool years and behyond, certain nonverbal skills, especially the frequency of initiating joint attention, and imitation, are strong predictors of language acquistion for children with autism (Charman et al, 2003).
- stereotyped movements
- rigid behaviour
- resistance to change, routines
- narrow area of interests
- Many with autism also have sensory processing difficulties (e.g. ear defenders)... some children are mistaken as being deaf due to low sensitivity to sound
- Baron-Cohen et al (1999) Torrence Creativity Tests - children with autism and AS show impairments.
- Wolfberg ( children with autism exhibit a range of sensory-oriented behaviours as mentioned above. May also carry out perseverative activity with objects (e.g. chewing toya, flicking light switches etc). These tend to appear in excess as repeated loops of behaviour (Frith, 2003).
Testing for Autism
- DSM-5 notes along with the triad of impairments, that :
- symptoms must be present in the early developmental period
- symptoms must cause clinically significant impairment in areas of current functioning
- these disturbances are not explained better by intellectual disability disorder or global developmental delay.
- Skuse et al (2005) conducted an assessment of whether the Social and Communication Disorders Checklist (SCDC) fulfils the need for a sensitive measure of autistic traits.
- consisted of 12 item scale and showed traits measured by the SCDC to be highly heritable in both genders (0.74). Excellent internal consistency (0.93) and high reliability (0.81). SCDC is useful screening questionnaire.
- Other measures used include the M-CHAT (Modified Checklist for Autism in Toddlers)... original CHAT was developed by Baron-Cohen et al (1992) but was found to be not sensitive enough for use. M-CHAT has much better sensitivity, and when it is failed, additional evaluation is recommended.
Why is autism increasing in frequency?
- Matson et al (2010) - Many hypotheses have been put forward
- expanded diagnostic criteria
- more awareness of the disorder
- diagnosis at earlier ages
- recognition that ASD is a lifelong condition
- They propose that the relatively frequent change in diagnostic criteria appears to be at the core of the increasing prevalence of ASD. Without controlling for the changes in diagnostic criteria, researchers cannot make such claims that increases are being observed.
- More and more parents are having their cchildren assessed who may previously not have, due to boosted awareness leading to more resources for testing children.
- Unless researchers are able to control for previously used diagnostic criteria, comparisons to previous prevalence estimates hold little information. To solve this debate, researchers are encouraged to standardize their diagnostic criteria and attempt to determine prevalence estimates in the past using the current diagnostic system.
MMR vaccine and infections in pregnancy
- Wakefield's 1998 paper was fraudulent - he altered numerous facts about patient's medical histories to support his claims (Godlee, 2011). Farrington et al (2001) provide evidence against the causaal association.
Infections during pregnancy
- Parner et al (2012) - found little evidence that various types of mild common infectious diseases in pregnancy were associated with ASD. But did find:
- twofold risk of infantile autism following maternal influenzea.
- prolonged episodes of fever caused threefold risk
- various antibiotics during pregnancy were potential risk factors.
- BUT: these aren't thought to be strong risk factors for ASD and they may be due to chance along with other methodological factors.
Baron-Cohen etl al (2009)
- fT levels were positively associated with higher scores on two instruments measuring autism. This relationship was seen within sex as well as when the sexes were combined, suggesting it is na effect of fT rather than sex per se.
Empathising and Systemising
Baron-Cohen et al (2002)
- Empathising involves two major elements:
- the ability to attribute mental states to oneself and others, as a natural way to understand agents
- having an emotional reaction that is appropriate to the other person's mental state, goes beyond ToM to include having some affective reaction (such as sympathy)
- These allow us to make sense of the behaviour of another agent we are observing, to predict what they might do next, and how they might feel.
- systemising can be defined as the drive to analyse and build systems, in order to understand and predict the behaviour of non-agentive events.
- invovles an initial analysis of the system down to its lowest level of detail in order to identify potentially relevant parameters that might play a causal role in the behaviour of the system.
Luna et al (2007)
- while executive dysfunction is present throughout development, there is evidence for both typical and atypical developmental progression of executive functions in autism.
Ozonoff et al (1994)
- Longitudinal study indicated that executive function:
- seriously deficient in autistic individuals
- improve with little development
- may never reach normal functioning levels
- appear to eventually hit a developmental ceiling
- Happe et al (2006) compared typically developing (TD) with ASD and ADHD and found:
- ASD group significantly worse on selection/monitoring in a cognitive estimates task.
- Age-related improvements were clearer in ASD and TD than ADHD. At older (but not younger) ages, ASD group outperformed ADHD group, performing as well s the TD group on many EF measures. Suggest less severe adn persistent EF deficits in ASD than ADHD.
Central Coherence explanation
- This theory related to the tendency to process information piecemeal, rather than integrate it.
Pellicano et al (2005)
- Autistic kids tend to perform superior to norms on the "Embedded Figures Test" - the task being to locate a 'hidden' figure from a larger, complex design. Those who succeed more quickly are thought to have a 'field-independent' cognitive processing style, rather than 'field-dependent', Autistic kids show good memory for verbatim, but poor gist memory
- Thought to support idea of CC, as their tendency towards processign details is viewed as a processing bias, though not an impairment.
- Used two tests to capture EF skills using fMRI to demonstrate that different areas within PFC are involved as a function of which test is being used. Depending on which of the two tasks was being used, there was a variation in the areas of the brain shown to be functioning abnormally
Central Coherence: perceptual processing
Shah & Frith (1993)
- Wechsler Block Design Task (moving blocks to match a pattern) -> due specifically to segmentation abilities
- Also excel at Embedded Figures Test (EFT) in which a small shape must be found within a larger design.
Heaton et al (1998)
- Weak CC thought to explain savant skills.
- musically naive autistic children are significantly better than matched controls at learning note names for individual pitches - the ability underlying absolute pitch.
- after about age 6, a general developmental shift from perceiving individual features to perceiving relations among features makes absolute pitch difficult or impossible to acquire.
- if people with autism show a pervasive and persistent local-processing bias, this wouuld explain the high frequency of absolute pitch and the superior ability to learn note-name mappings at later ages.