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Autism Spectrum Disorder. Background. Pervasive Developmental Disorder (PDD). Deficits in social relatedness, communication and restricted interests/ behaviours. Autism Spectrum Disorder (ASD). Autistic Disorder Asperger’s Disorder - PowerPoint PPT Presentation
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Autism Spectrum Disorder
Autistic DisorderAsperger’s DisorderPervasive Developmental Disorder Not Otherwise Specified
(PDD-NOS)
ASD {
Pervasive Developmental Disorder (PDD)
Deficits in social relatedness, communication and restricted interests/behaviours
Non-clinical Severe
Background
Autism Spectrum Disorder (ASD)
SPECTRUM
-Highly heritable-3-4 males for every female-1/110 estimated prevalence
Domains of Impairment in ASD
Domain Autism Asperger's PDD-NOS ASD
social communication required required required
language required variable
repetitive, restrictive behaviours required required variable
sensory abnormalities >90% 80% variable 94%
developmental regression 15-40% ? ? 15-40%
motor signs 60-80% 60% 60% 60-80%
gross motor delay 10% ? ? 5-10%
sleep disturbance 55% 5-10% 40% 50%
gastrointestinal disturbance 45% 4% 50% 4-50%
epilepsy 10-60% 0-5% 5-40% 6-60%
comorbid psychiatric diagnosis 70% 60% >25% 25-70%
Geschwind, Ann Rev Med (2009)
Comorbidity in ASD
Disorder %Depression 19.6
Generalized Anxiety Disorder 14.3Social Phobia 10.7
Obsessive Compulsive Disorder 3.6Panic Disorder 3.6Agoraphobia 3.6
ADHD 16.1Oppositional Defiant Disorder 10.7
Tics/Tourette's 1.8Catatonia 1.8
Autism SPECTRUM Disorder
SocialAloofPrefers to be aloneDifficult to engage
Likes to interactWants friendsDoesn’t “get” social rules
CommunicationLimited communicationUses only physical means
Conversational languageOne sided conversations
Restricted Activities/InterestsSensory/Motoric(e.g. spinning, tapping)
Routines/focused interests(e.g. obsession with calendars)
Brain Size
(Mraz et al. 2007)
Accelerated rates of brain growthduring early development
Result: An increase in the ratio oflocal relative to long distanceconnections
Areas most affected:Frontal and Temporal Lobes
ASD: 3 stages of brain growthovergrowth, arrest, decline
Sensory Systems - Visual
CC
CC+
Ashwin et al. (2009)
Freiburg Visual Acuity and Contrast Test-gaps 0.4 mm to 25 mm-use arrow keys to indicate location of gap
-visual acuity expressed in the form 20:x-average vision is 20:20 or the detail that one can see from 20 feet away
Sensory abnormalities and/or sensory hypersensitivity in ASDDocumentation of both superior and inferior sensory processing
(Ashwin et al. 2009)
AVG = 2.79
AVG = 1.44
-ASD group 2.79 times better than average-Visual Acuity Controls: 20:13-Visual Acuity ASD: 20:7
ASD group can see detail of an object 20 feet away as a person with average vision would see from 7 feet away!
ASD visual acuity approximates thatof birds of prey.
Results:
Sensory Systems – Visual
Sensory Systems - Auditory
Also …People with ASD have
normal to superior performance in pitch
discrimination and music abilities
Increased perception of loudness in ASD
(Khalfa et al. 2004)
Sensory Systems
-Abnormalities in the integration of parts and wholes -Local range over-connectivity-Sensory hypersensitivity
-could affect information processing that could cause distressbut could also predispose to unusual talent
Theories?
-a subgroup of those with ASD with profound expertise or ability
-more prevalent in ASD than any other neurological group
Savantism
The Extreme Male Brain Theory
(Falter et al. 2008)
ASD group preformed betteroverall as compared to controls
Females good at empathizingMales good at systemizing
Men out preform women on tasks requiring systemizinge.g. visuospatial tasks
ASD brain believed to be anexaggerated form of the male brain
Recall the mental rotation task:
Face ProcessingPierce et al. 2001
Face Perception Task
Fusiform gyrus, superior temporal sulcus and amygdala activation in controls.Lack of this activation in the ASD group.
Conclusion: Face processing occurs outside the FFA in ASD
Face ProcessingPierce et al. 2004
Face Processing Task Amended-used stranger AND familiar faces
Results:With familiar faces, normal FFAactivity was found in the ASD group
ASD group showed similar network activation to controls only to familiar faces
Amygdala can be responsive in ASD in the presence of stimuli that is of highemotional value
Conclusion:ASD related FFA dysfunction may reflect deficitsin systems that modulate the FFA rather thanthe FFA itself.
LanguageLanguage and communication deficits a core feature of ASD
Difficulties with:Pragmatics – problems using language within a social contextArticulation - poor oro-motor controlProsody – speaking with monotone or an exaggerated singing prosodySemantics – difficulty understanding the meanings of wordsGrammar – pronoun reversal; speaking in grammatical sentences
Echolalia: repetition of another person’s spoken words
Language
Broca’s Area: production of speech
(Fosse et al. 2004)
Reversed asymmetry of Broca’s area(R>L) in language-impaired ASD and those with a specific language impairment
Volumetric Analysis of Broca’s area
Symmetry reversal of Broca’s Area is more closely related to a languageimpairment than to a diagnosis of ASD
LanguageHarris et al. 2006
Semantic Processing Task-Subjects indicated whether a word was +/- (Semantic) or whether a word was in upper/lower case (Perceptual)
ResultsReduced Broca’s area activation for ASD group during semantic processing
Conclusion
Autism…. It is complex and complicated
Just trying to put the puzzle together one piece at a time!