ASD Flashcards
What is the epidemiology of ASD?
700,000 people on the spectrum in the UK = >1%
More common in boys
i) But might be due to diagnostic methods (very biased to look for ‘male’ presentations)
Prevalence increasing with time
i) Again, might be due to diagnostic methods rather than an actual increase
One in every school year in Sheffield
What is the aetiology of ASD?
Polygenic
High heritability for autistic traits demonstrated by twin studies:
Various studies from 1977-2006 have shown heritability to be between 36-95.7%
The upper end of this range is associated with concordance of a broader phenotype (i.e. displaying a few autistic traits rather than full phenotype)
Sibling studies:
Greater prevalence of autism in siblings of autistic children
Though there are some cases of autism where a single gene abnormality, chromosomal abnormality or other genetic syndrome is the sole cause – ASD is associated with other genetic disorders in these instances e.g. fragile X syndrome
What are some other risk factors for ASD?
Paternal age – older
Maternal psychiatric diagnosis or FHx – depression, schizophrenia, OCD
Gestational diabetes
Male
Urban neighbourhoods of high socioeconomic status
(but both might be diagnostic biases)
What is the ‘vaccine hypothesis’?
Based on a paper by Andrew Wakefield in 1998 that found a ‘causal link’ between the MMR vaccine and development of ASD
Data included in the report was later shown to be false and Wakefield lost his license to practice
What is ASD often comorbid with?
Genetic disorders – single gene/chromosomal abnormality or other genetic syndrome i.e. fragile X syndrome, Rett syndrome
Intellectual disability – 25-70% (difficult to assess intelligence)
Anxiety disorders – 11-84%
Epilepsy – 5-38%
What is the pathophysiology of ASD?
Neurodevelopmental disorder
No clear unifying mechanism for its cause
Developmental factors (genetic + environmental) → affect many/all functional brain systems → alteration of timing of brain development
Neuroanatomical changes in those affected - brains grow faster just postpartum then slower though childhood (though maybe not in all children with autism)
Other hypotheses include – mirror neuron system abnormalities; default mode network-task positive network abnormalities and underconnectivity theories, GI abnormalities, microbiota changes and immune dysfunction
What are some neuropsychological theories of ASD?
Empathising-systemising theory:
Autistic individuals can systemise – develop internal rules of operation to handle events inside the brain – but not empathise as well
The autistic brain is the ‘extreme male brain’ – systemising > empathising
Weak central coherence theory:
Perceptual cognitive style colloquially described as a ‘limited ability to understand the context/to see the big picture’, but conversely an aptitude for detail
May explain why some people on the spectrum excel in maths/engineering etc but have trouble with language skills
What are some difficulties with social communication?
Communication of their needs only
Disordered or delayed language - starting talking then stopping at some point is a red flag
Echolalia - repetition of sounds
Poor non-verbal communication - eye contact is challenging
Pedantic language, literal, little/no understanding idioms and jokes
What are some difficulties with social interaction?
No desire or interested but unsure of others conversations + how to interact
Friendly but odd, possible inappropriate touching/issues with personal space
Limited interactions with unfamiliar people, plays alone
Rejecting cuddles initiated by parents/cares (though may initiate themselves)
What are some difficulties with social imagination?
Learns rules e.g. social and app lie to multiple settings in an obvious/not fluid or flexible way; follows enforced rules exactly
Less fantasy play, reduced ability to write imaginatively
Resistant to change
Repetitive games
Obsessions and rituals
Special interests - relaxing to the individual (unlike OCD)
Poor empathy
Asks same questions even when answered - because anxiety or inattention
What are some sensory difficulties in ASD?
Unusual sensory interests
Confusing different senses
Hyper/hyposensitive
Very distressed with lots of noise
Strong likes/dislikes of food based on texture or colour as much as the taste
What are some repetitive and restrictive behaviours (RRBs) in ASD?
Stereotyped or repetitive speech, motor movements, or use of objects (such as simple motor stereotypies, echolalia, repetitive use of objects, or idiosyncratic phrases)
Excessive adherence to routines, ritualized patterns of verbal or nonverbal behavior, or excessive resistance to change (such as motoric rituals, insistence on same route or food, repetitive questioning or extreme distress at small changes)
Highly restricted, fixated interests that are abnormal in intensity or focus (such as strong attachment to or preoccupation with unusual objects, excessively circumscribed or perseverative interests)
Hyper-or hypo-reactivity to sensory input or unusual interest in sensory aspects of environment (such as apparent indifference to pain/heat/cold, adverse response to specific sounds or textures, excessive smelling or touching of objects, fascination with lights or spinning objects)
How are people diagnosed with ASD?
People have a series of observations or clinical interviews where behaviours are explored and coded
Everyone gets the ASD umbrella label and each child’s difficulties are described separately
This is all a spectrum obviously and individuals can be high functioning or low functioning with these symptoms presenting in a variety of combinations and intensities
Diagnosis can take an age…
What are some sex differences in ASD?
Asperger’s in girls is now thought to be more common than previously thought
Girls are especially good at learning from others the ‘normal’ ways to behave and in so doing, manage to hide their true self beneath this superficial cloak of other peoples behaviours
How is ASD managed?
Education and information
Different types of communication aids e.g. pictorial - visual timetables or instructions
School support + work support
Manage comorbidity
