Lecture 10: Autism Spectrum Disorder Flashcards
What is autism?
a relatively common and diverse neurodevelopmental condition
manifests across the lifespan
associated with a continuum of needs and abilities
What is the epidemiology of autism?
more common in boys (sex ratio about 4:1)
genetic, epigenetic and environmental factors likely play a role
prevalence estimated at 1 in 50
likelihood to siblings estimated at 8-18%
rates relatively consistent across international studies
prevalence estimates steadily increasing over past 40 years
What is the biomedical perspectives on how autism is viewed?
clarify biological subtypes to promote treatments at underlying etiology
autism as diagnosis
implement results from symptoms
diagnostic language is used to represent clinical needs and heterogeneity
What is the neurodiversity and social model perspectives on how autism is viewed?
emancipatory aims, removes diagnosis and all references to medical classification
autism as identity
disability from barriers in the physical and/or social environment
language related to symptoms and levels of support viewed as stigmatizing and pejorative
What is the DSM-5 criteria for ASD?
deficits in social reciprocity (e.g. social approach, sharing interests & affects)
deficits in nonverbal communication used for social interaction
deficits in developing relationships appropriate to developmental level
repetitive speech, motor movements or use of objects
excessive adherence to routines and ritualized patterns of behavior
restricted, fixated interests
hyper- or hypo-reactivity to sensory input or unusual sensory interests
What is social-emotional reciprocity?
tailoring and adjusting social behavior across diversity of partners and contexts (perspective taking, ability to “shift gears” based on others roles/relationships, cues, intentions)
What are nonverbal communicative behaviors?
socially directed, multiple modes coordinated, adjustment to context, fluency/effort (note “masking”)
What is the develop and maintenance of relationships?
within and outside family, understanding of different types of relationships and what’s expected within each, friendships
What are intense interests?
degree of focus, duration, impact
What are repetitive speech, movements, or use of objects?
scripted language, formality/choice of words
use of toys and other materials
motor aspects
What is the preference for sameness, specific routines/rituals?
“what can’t be changed”
reactions to small changes
ritual = fixed sequence
transitions/”shifting gears”
What is reactivity to sensory environment?
sensations avoided and sought
threshold and intensity of reaction, adaptations may be needed
What are the unique features of ASD in the DSM-5 compared to previous criteria?
diagnostic qualifiers rather than subtypes (e.g. language, intellectual ability)
no more “Asperger Syndrome”
severity (in each symptom domain) related to level of support needed
flexibility in age of onset: “early but may not be evident until demands overwhelm capacity”
facilitates diagnosis in older youth and adults
What are the steps of diagnosing autism spectrum disorder?
general developmental surveillance
autism-focused surveillance
diagnostic assessment
What are the signs of autism in the first 18 months?
orients to name
social (solitary) babbling
eye contact
social interest and affect
social referencing
transitions
insistence on partic object
atypical sensory behavior
engagement of attention
What is the best practice in autism diagnosis?
determine definitive diagnosis
explore co-occurring conditions (which may overlap with autism)
determine adaptive function, strengths, challenges, interests
gather sufficient information to inform treatment planning
What is the assessment of autism spectrum disorder?
structured developmental and medical history: initial concerns, developmental course, autism features/symptoms, medical issues, family and psychosocial history
structures observation of social, communication, and play-related behaviors
developmental context: assessment of language, cognitive and adaptive skills
What is the community model of diagnosis?
collaborative/”virtual team”
less complexity
ongoing mentorship
What is the specialty team pathway of diagnosis?
multi-disciplinary
more complexity
consults as needed
What is the diversity of autism spectrum disorder?
across continuum of language and intellectual abilities (minority are intellectually disabled)
across the lifespan
across ethnicities (importance of intersectionality)
across sexes and gender identities (girls and women may be underidentified)
What are the distinct patterns of brain development in autism?
acceleration in brain growth to age 2-3 years (post-natal onset)
neural connectivity
neuropathologic findings
pattern of brain activation with social perceptual tasks: decreased activation of fusiform gyrus during facial recognition, less amygdala activation and poorer performance on tasks requiring autistic people to judge facial emotion
What is the accelerated brain growth in ASD?
increased head circumference and brain volume most consistently replicated (macrocephaly in about 20-30%)
recent studies indicate a post-natal onset: no HC differences on prenatal US, average or below average head size and birth, with accelerated head growth during first 2-3 years
increased cortical surface area rather than cortical thickness
What are the white matter differences in autism?
evidence that white matter is disproportionately enlarged, relative to gray matter (with “catch-down” to non-ASD controls by adulthood)
white matter volume increase is primarily found in subcortical areas and in origins and terminations of projection and sensory fibers
corpus callosum is abnormally small, relative to total brain volume
structural and functional neuroimaging studies consistent with increased local and reduced distal connectivity
What are the genetic contribution to autism?
concordance higher in monozygotic than dizygotic twins (first reported in 1977) implies that genes are involved
role of both common and rare genetic variants (including syndromic forms of autism)
genetic overlap with other conditions
ASD genes are “meeting at the synapse”
many of the “ASD risk genes” identified have roles in regulating gene expression or neuronal communication
