Lifespan A: Autism, WEEK 9 Flashcards
1
Q
History of autism diagnosis
A
- Observations can be used to try and detect if a child has autism as well as taking detailed accounts of child history
- Kenner + Asperger found common difficulties in kids w/ ASD such as difficulty communicating, interacting w/ others, prefer rigid routines > argue this emerges early
2
Q
Autistic aloneness
A
- desire to be by oneself + not think about others around you
3
Q
Diagnosing ASD
A
- 2 core features of ASD:
1. Persistent deficits in social communication and social interaction across contexts > Deficits in social-emotional reciprocity (e.g.conversations), Deficits in non-verbal + verbal communication(e.g., eye contact, facial expressions), Deficits in developing relationships (e.g., making friends)
2. Restricted, repetitive behaviours, activities or interests: Stereotyped, repetitive motor movements or speech (e.g. hand flapping or rocking), Insistence on sameness, inflexible routines, ritual patterns of behaviour, Restricted interests that are abnormal in intensity, Hyper-reactivity to sensory aspects of environment (e.g. noise,sound) - To be diagnosed w/ ASD, it has to emerge early in life + show both different conditions and cannot be explained by other problems like deafness > symptoms need to be severe enough to impact social functioning
4
Q
Core features of ASD
A
- Communication difficulties:
Echolalia, Neologisms, Conversation problems, Language delays, Poor eye contact - Social Interaction Difficulties: Lack interest in others, Difficulties with reciprocity, Difficulties with understanding others’ thoughts/emotions
- Restricted, Repetitive Behaviours + Interests: Stereotyped repetitive movements, Obsessional interests, Insistence on sameness, Unusual memory
- These symptoms separate ASD children from TD or other disorders
5
Q
Causal model of Developmental Disorders
A
- Frith + Morton suggest we should think about theories in terms of multiple levels of explanations
- Most psychiatric/psychological disorders are defined at a behaviour level (lowest level) w/ no blood test for ASD
- Behavioural level > behavioural features move commonly occurring behaviours together suggesting they are apart of a consistent disorder
- A cognitive process may substantiate these behaviour features (how we think is affecting our behaviour?)
- Cognitive process impacting behaviour may be impacted by our biology (why we think the way we do?)
- EV can impact any one of these levels
- Levels: Biological (top) influencing cognitive (middle) influencing behaviour (bottom)
6
Q
Heritability in Autism
A
- ASD definitely has a genetic component > heritable disorder
- Concordance rates looked at whether MZ twins are more likely to have ASD together vs DZ twins > Folsten + Rutter find 36% conc in MZ twins + 0% in DZ > if one twin has ASD, the other was more likely to have ASD if MZ
- Meta analysis on 7 twin studies found median estimate of MZ conc was 76% + 0% for DZ
- Another meta analysis looking at 13 twin studies to find how much genes accounted for variance finds genes account for 93% while EV accounts for 7%
- Twin studies don’t tell us what genes are involved
7
Q
Complex inheritance: Two Perspectives
Common Variants
A
- Complex traits (disorders) are caused by common variants: Common disease, common variant model > Caused by many common alleles each having a small effect.
- Common variants meaning alleles that occur in genpop in more than 1% of people > if you have lots of common variants, they add up to be a causal factor in a common disorder like autism
- Autism is in 1% of pop (common) > is autism due to multiple common variants
8
Q
Complex inheritance: Two Perspectives
Rare variants
A
- Complex traits (disorders) are caused by rare variants: Multiple rare variants model > Caused by many mutations (de novo mutations)/rare variants each with a powerful effect.
- Multiple rare variant is one occurring in less than 1% of pop > rare variant can be inherited but is infrequent in genpop
- De Novo mutations are those which occur in specific child + is not passed through generations
- If you have many rare variants + mutations in genome, you are at greater risk of ASD
9
Q
Genome Wide Association
A
- Single nucleotide polymorphism (SNP): where gene varies in one part of code > alleles are polymorphic
- SNP from across Genome are identified (1 mill approx)
- Compare cases (disorder) versus controls (no disorder) > Are cases more likely to have the minor (less frequent) allele?
- Identify profile of variants that explain variance in disorder.
- GWA research shows no variant explains more than 1% of total variance in ASD but combination of genes account for substantial proportion of variance in autism symptoms
- Gaugler et Al finds 49% of variance in ASD is explained by common variants > 3% is explained by rare inherited variants + 3% explained by de novo mutation > half of variance in ASD is explained by genes but the other half is unaccounted > EV factor?
10
Q
Environmental factors
A
- When mothers experience extreme prenatal levels of stress, this stress can produce certain hormones that alter the dev of hypothalamic pituitary adrenal axis > this is linked to stress + can alter dev of foetus brain
> counts as EV as utero is EV of foetus - Kinney et Al looked at pregnancy during severe storms > 320,686 births over a 16 year period > found people w/ higher exposure to storms thus more severe stress had more cases of ASD (13/10000) while those with low exposure had 4/10000
- Prenatal EV factors can impact likeliness of dev ASD
11
Q
Mind-blindness
A
- Suggests that the core deficit in ASD may be the underlying difficulty to think about minds/view of others
- Tested hyp w/ 20 children w/ ASD, 14 w/ downs syndrome (intellectual problems w/ no social difficulties) and 27 TD
- All children passed control questions, 85% of controls (TD) children passed the false belief, 86% of children with Downs passed the false belief, 80% of children with ASD failed the false belief
- Argues those w/ ASD have difficulty w/ social interaction + communication is due to underlying cognitive deficit in ToM > this is mind-blindness
12
Q
Meta-analysis of ToM & ASD
A
- TD children + children w/ intellectual disability outperformed children w/ ASD on measures of ToM
- Cohen’s D = effect sizes > strong diff between groups
- TD compared to ASD > d= .88 > big difference
- Intellectual disability to ASD > d= .84
- TD compared to Intellectual disability > d= .45
- Although the difference is smaller, TD kids still outperform those w/ intellectual disability > other factors impact performance
13
Q
Explaining mind-blindness: Baron-Cohen (1995)
A
- Because autism is largely heritable, these ToM deficits are caused by something innate > innate deficit in mind-reading > ToM is underpinned by innate domain specific modules > autism is characterised by damage to these modules
- Deficits in ToM occur across many measures: Joint attention, False Belief, Deception, Emotion understanding
14
Q
What damage causes mind-blindness?
A
- Abnormalities in the superior temporal sulcus + medial pre-frontal cortex lead to deficit in mind reading which causes the symptoms of autism
15
Q
Challenges to mind-blindness
A
- Evidence suggests heritability of ToM is low > ToM is predicted by a range of early family experiences
- ToM is correlated w/ language ability + with EF
- Mind-blindness doesn’t explain non-social symptoms of ASD > restricted + repetitive behaviours
- Improvements in ToM in ASD do not lead to improved social skill > challenges suggest there is not a direct dev link between mind-blindness + social problems in those w/ ASD
