Lecture 10: Autism Spectrum Disorder

Question 1

What is autism?

Answer 1

a relatively common and diverse neurodevelopmental condition

manifests across the lifespan

associated with a continuum of needs and abilities

Question 2

What is the epidemiology of autism?

Answer 2

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

Question 3

What is the biomedical perspectives on how autism is viewed?

Answer 3

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

Question 4

What is the neurodiversity and social model perspectives on how autism is viewed?

Answer 4

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

Question 5

What is the DSM-5 criteria for ASD?

Answer 5

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

Question 6

What is social-emotional reciprocity?

Answer 6

tailoring and adjusting social behavior across diversity of partners and contexts (perspective taking, ability to “shift gears” based on others roles/relationships, cues, intentions)

Question 7

What are nonverbal communicative behaviors?

Answer 7

socially directed, multiple modes coordinated, adjustment to context, fluency/effort (note “masking”)

Question 8

What is the develop and maintenance of relationships?

Answer 8

within and outside family, understanding of different types of relationships and what’s expected within each, friendships

Question 9

What are intense interests?

Answer 9

degree of focus, duration, impact

Question 10

What are repetitive speech, movements, or use of objects?

Answer 10

scripted language, formality/choice of words

use of toys and other materials

motor aspects

Question 11

What is the preference for sameness, specific routines/rituals?

Answer 11

“what can’t be changed”

reactions to small changes

ritual = fixed sequence

transitions/”shifting gears”

Question 12

What is reactivity to sensory environment?

Answer 12

sensations avoided and sought

threshold and intensity of reaction, adaptations may be needed

Question 13

What are the unique features of ASD in the DSM-5 compared to previous criteria?

Answer 13

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

Question 14

What are the steps of diagnosing autism spectrum disorder?

Answer 14

general developmental surveillance

autism-focused surveillance

diagnostic assessment

Question 15

What are the signs of autism in the first 18 months?

Answer 15

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

Question 16

What is the best practice in autism diagnosis?

Answer 16

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

Question 17

What is the assessment of autism spectrum disorder?

Answer 17

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

Question 18

What is the community model of diagnosis?

Answer 18

collaborative/”virtual team”

less complexity

ongoing mentorship

Question 19

What is the specialty team pathway of diagnosis?

Answer 19

multi-disciplinary

more complexity

consults as needed

Question 20

What is the diversity of autism spectrum disorder?

Answer 20

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)

Question 21

What are the distinct patterns of brain development in autism?

Answer 21

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

Question 22

What is the accelerated brain growth in ASD?

Answer 22

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

Question 23

What are the white matter differences in autism?

Answer 23

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

Question 24

What are the genetic contribution to autism?

Answer 24

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

Question 25

What is the potential role of “non-genetic” contributions to autism?

Answer 25

concordance among identical twins = 60%, concordance higher for broader phenotype; could environment interact with genetic vulnerability

rise in prevalence inconsistent with purely genetic mechanism

modest evidence base implicating certain exposure

Question 26

What are the indications for EEG in ASD?

Answer 26

EEG not justified in children with ASD and “regression”; does not alter management

Question 27

What are the indications for neuroimaging?

Answer 27

only indicated with specific comorbid diagnosis (e.g., Tuberous Sclerosis) or localizing findings