Autism

Autism: Where we are

Neurodevelopmental disorder

  • Genetic Basis (Abrahams & Geschwind, 2008; Daly et al., 2012):
    • concordance in identical twins ~90%
    • rare genetic mutations (account for 10-20% of cases)
    • multifactorial – 400-1000 risk genes? atypical brain development
    • BUT currently no genetic or biological markers identified
  • Diagnosis is behavioural
    • defined set of criteria
    • social communication, repetitve behaviours

Difficulty and problem with diagnosing autism

  • different causes of the same behaviour (convergence)
  • different manifestations of the same cause (divergence)
  • ‘shopping list’ criteria
  • leads to heterogeneity
  • leads to treatment of symptoms, not cause

 

Prevalence

  • Prevalence has hugely increased
  • prevalence is not incidence
  • incidence may be the same

Reasons for prevalence/increase of prevalence

  • Autism has almost certainly always existed
  • Change in the definition of autism
  • More awareness
  • Increased understanding of compensation

Heterogeneity

  • Behavioural heterogeneity → autism spectrum
  • varying in multiple dimensions
  • severity of symptoms, pattern of symptoms
  • manifestation of difficulties at different developmental stages and levels of general ability
  • hard to identify biological and genetic factors

Cognition

  • point of greatest convergence in the causal chain → homogeneity
  • describes the functions of the mind
  • critical level to study autism
  • allows range of behaviours to be linked to a unitary cause

 

Cognitive theories of autism

Social theories

  • mentalizing/ToM – difficulty in representing another’s mental state as distinct from your own
  • social motivation – social stimuli are not rewarding
  • social attention – social stimuli are not given priority
  • social perception – social stimuli are processed differently

Domain general theories

  • executive function – weaker higher order control of thoughts and actions
  • local bias – preference for processing local details

Cognitive theories of autism

  • All attempt to explain a variety of behaviours
    • BUT none appear sufficient to account for all behavioural manifestations across different individuals
    • fractionation of autism at a cognitive level?
  • Often assumed to be present in all individuals with ASD
    • BUT it has also been suggested that cognitive heterogeneity may be more characteristic of autism than any single cognitive profile (Towgood et al., 2009)
    • ‘the autisms’ at a cognitive level?

Local Bias

  • <<Tendency to process local detail at the expense of global meaning<<
    • an information processing style
    • a continuum
    • can be an advantage
  • <<Attempts to explain certain non-diagnostic symptoms<<
    • preoccupation with parts
    • noticing small changes
    • good rote memory
    • literal mindedness
  • <<Islets of ability<<
    • ‘savant skills‘
    • music, art, maths, perfect pitch
    • Art by Stephen Wiltshire

Cognitive Mechanism (Mann & Walker, 2003)

  • difficulty ‘zooming out’
  • difficulty broadening the spread of attention
  • difficulty switching from local into global processing
  • fits with parts of DSM-V
    • ‘difficulty changing focus’
    • ‘difficulty with transitions’
    • ‘difficulty switching between activities’
  • general switching problem or directional?

Visuo-spatial tests - Embedded Figures

 

Visual perceptual tests - Visual Illusions

 

 

Controversy

Variable findings
  • some studies find differences, others don’t
  • only true for some individuals?
  • doesn’t explain diagnostic symptoms so that’s OK!
Top-down/bottom-up
  • caused by basic sensory differences → Mottron et al. / Plaisted et al.
  • caused by poor top down control? → Frith et al. / HappĂ© et al.
  • part and parcel of the same thing?

Theory of Mind

Mentalising

  • allows us to predict behaviour on the basis of mental states (wishes, beliefs, feelings)
  • ‘mind reading’ – not a theory but an everyday unconscious activity
  • makes us better at understanding what other people are doing
  • enables us to monitor the intentions of others/why they’re doing s/t
  • Autistic children fail to understand mental states at an appropriate age
Mentalising difficulties
  • Difficulty in representing another’s mental states as distinct from your own
  • ‘mind blindness’
    • not putting yourself into someone else’ shoes
    • not recognising what another person thinks or feels
    • not properly communicating
False belief
  • requires prediction of action on basis of attribution of false belief to other person (not on basis of own belief or reality)
  • Sally-Anne task -> (Baron-Cohen, Leslie & Frith, 1985)
Autistic children fail to understand mental states at an appropriate age
  • This impairment is specific to mental states rather than just processing alternatives
  • Such as changes in physical states

![Leslie & Thaiss, 1992

](https://knowt-user-attachments.s3.amazonaws.com/1cda8b8378564ba1a991c47fecfc2172.jpeg)

Mentalising
  • most autistic people fail ‘theory of mind’ tests at an age when they should pass them
  • in everyday life, their social and communicative difficulties fit a pattern of ‘mind-blindness’
  • Hence, persistent difficulty in implicit Theory of Mind?
Older autistic individuals* often pass mentalizing tests ( *without co-occurring intellectual disabilities, and age appropriate verbal and non-verbal abilities)
  • did they ever actually have ToM difficulties?
  • can ToM be acquired, with long delay?
  • can we still pick up more subtle difficulties in older autistic individuals who do not have co-occurring intellectual disabilities?
  • is their ‘ToM’ really the same?
    • implicit vs explicit?
    • compensation? ‘hacking out’ a solution?
Animations - an advanced mentalising test (Abell, Happé & Frith, 2000)

 

Animations - neural basis of ToM (Castelli, Frith, Happé & Frith, 2002)
  • Volunteers scanned (fMRI) whilst watching animations
  • Compare brain activity whilst thinking about mental states vs. goal-directed / random animations
  • Different patterns of activation in autistic and non-autistic participants
    • mentalizing system is under-activated
    • visual system is normally activated
  • the same brain regions are activated by a host of other tasks
  • Mentalizing ability seems to improve with age in autism, but subtle mentalizing difficulties are still present, both in terms of task performance and mentalizing-related brain activity
Difficulty in spontaneous ToM
  • ASC adults show a difficulty in spontaneous mentalizing through anticipatory eye movements on the most basic of tasks despite passing them explicitly
  • intact task performance does not equate to intact spontaneous mentalizing
    • → compensation

Theory of Mind 2

  • ToM difficulties in autism is specific to mental states
  • implicit ToM is impaired even when explicit ToM performance is intact
  • universality/heterogeneity of ToM?

Strange stories (White, Hill, Happé & Frith, 2009)

 

 

  • ASC group show a marked difficulties on the mental state stories
  • again, still able to detect ToM difficulties in these high-functioning individuals with ASD

 

  • Strange Stories - children
    • most studies report group means
    • what about individuals?
    • distinct heterogeneity
    • only some children with ASC show ToM difficulties?
    • or some managing to compensate
    • divide into ToM+ (good ToM) and ToM- (poor ToM)

     

Strange Stories - neural basis of heterogeneity (White, Frith, Rellecke, Al-Noor & Gilbert, 2014)

 

  • mental vs. nature stories
    • across whole sample
    • mPFC, PCC, bilateral TPJ-temporal poles
    • use these regions in an ROI analysis

 

 

 

  • atypical brain activity in mentalising network in autism
    • regardless of performance on explicit tests
    • ToM impairment universal feature of autism?
    • ToM as a neurocognitive phenotype of socio-communicative difficulties
    • lends credence to clinical intuition of unifying specific impairment in autism
  • compensation (explicit test performance) –how is it achieved?
    • despite underlying mentalizing difficulties
    • occurring spontaneously early on?
    • little effect on socio-communicative symptoms
Compensation (Lai et al., 2016; Livingston & Happé, 2017; Hull et al 2017)
  • discrepancy definitions
    • difference between explicit and implicit mentalizing
    • different between mentalizing ability and behaviour
    • behavioural - camouflaging/masking – female presentation of autism
  • possible mechanisms
    • refer to a vast memory bank of behavioural contingencies gathered from environment
    • executive functions/top down control (see Johnson, 2012)
    • verbal reasoning skills
    • intelligence/general non-specific resources
  • cost of compensation
    • time – slow responses – ‘missed the moment’
    • exhaustion
    • self-awareness – stress/anxiety – mental health
Summary: ToM
  • ToM difficulties in autism is specific to mental states
  • Implicit ToM difficulties appear to be universal in autism – implicit ToM appears to be affected even when explicit ToM performance is intact
  • Explicit ToM performance intact in a subgroup from early in development despite atypical ToM-related brain activity

The Double Empathy Problem (Edey et al., 2016)

  • Social impairments faced by autistic individuals not only due to impaired cognition, but also due to breakdown of mutual understanding, empathy and reciprocity.
  • Non-autistic individuals find autistic individuals’ spontaneous reactions to social event difficult to interpret
  • Non-autistic observers rate behaviour of autistic people significantly less favourably.
  • Information transfer along diffusion chains: significantly more decline in detail retention in mixed autistic-non autistic chains v/s autistic only and non autistic only chains.
  • Autistic individuals better at attributing mental states to animations created by other autistic individuals than those created by other non-autistic individuals.
  • Non-autistic participants were better at attributing the correct mental state to the triangles over all, but better at mentalizing for animations generated by other non-autistic participants versus those generated by other autistic participants

Conclusion

  • Autism is currently defined by behaviour
  • We need cognitive theories to explain particular behaviours
  • Local bias accounts for superior abilities and other non-diagnostic features
  • ToM impairment is universal and long-lasting, accounts for social and communication symptoms
  • Cognitive theories help us to understand autism and have led to new knowledge about the brain
  • Socio-communicative difficulties autistic individuals face may not be only due to ‘autistic cognition’ but due to a breakdown in reciprocity between autistic and non-autistic individuals