Autism Spectrum Disorder

1. Autism Spectrum Disorder

2. Background Pervasive Developmental Disorder (PDD) Deficits in social relatedness, communication and restricted interests/behaviours Autism Spectrum Disorder (ASD) Autistic Disorder Asperger’s Disorder Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS) { ASD -Highly heritable -3-4 males for every female -1/110 estimated prevalence SPECTRUM Non-clinical Severe

3. Domains of Impairment in ASD Geschwind, Ann Rev Med (2009)

4. Comorbidity in ASD

5. Autism SPECTRUM Disorder Social Aloof Prefers to be alone Difficult to engage Likes to interact Wants friends Doesn’t “get” social rules Communication Limited communication Uses only physical means Conversational language One sided conversations Restricted Activities/Interests Sensory/Motoric (e.g. spinning, tapping) Routines/focused interests (e.g. obsession with calendars)

6. Brain Size Accelerated rates of brain growth during early development Result: An increase in the ratio of local relative to long distance connections Areas most affected: Frontal and Temporal Lobes ASD: 3 stages of brain growth overgrowth, arrest, decline (Mraz et al. 2007)

7. Sensory Systems - Visual Sensory abnormalities and/or sensory hypersensitivity in ASD Documentation of both superior and inferior sensory processing C 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 C C + C

8. Sensory Systems – Visual Results: -ASD group 2.79 times better than average -Visual Acuity Controls: 20:13 -Visual Acuity ASD: 20:7 AVG = 2.79 ASD group can see detail of an object 20 feet away as a person with average vision would see from 7 feet away! AVG = 1.44 ASD visual acuity approximates that of birds of prey. (Ashwin et al. 2009)

9. Sensory Systems - Auditory Increased perception of loudness in ASD Also … People with ASD have normal to superior performance in pitch discrimination and music abilities (Khalfa et al. 2004)

10. Sensory Systems Theories? -Abnormalities in the integration of parts and wholes -Local range over-connectivity -Sensory hypersensitivity -could affect information processing that could cause distress but could also predispose to unusual talent Savantism -a subgroup of those with ASD with profound expertise or ability -more prevalent in ASD than any other neurological group

11. The Extreme Male Brain Theory Recall the mental rotation task: Females good at empathizing Males good at systemizing Men out preform women on tasks requiring systemizing e.g. visuospatial tasks ASD group preformed better overall as compared to controls ASD brain believed to be an exaggerated form of the male brain (Falter et al. 2008)

12. Face Processing Pierce 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

13. Face Processing Pierce et al. 2004 Face Processing Task Amended -used stranger AND familiar faces Results: With familiar faces, normal FFA activity 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 high emotional value Conclusion: ASD related FFA dysfunction may reflect deficits in systems that modulate the FFA rather than the FFA itself.

14. Language Language and communication deficits a core feature of ASD Difficulties with: Pragmatics – problems using language within a social context Articulation - poor oro-motor control Prosody – speaking with monotone or an exaggerated singing prosody Semantics – difficulty understanding the meanings of words Grammar – pronoun reversal; speaking in grammatical sentences Echolalia: repetition of another person’s spoken words

15. Language Broca’s Area: production of speech Volumetric Analysis of Broca’s area Reversed asymmetry of Broca’s area (R>L) in language-impaired ASD and those with a specific language impairment Symmetry reversal of Broca’s Area is more closely related to a language impairment than to a diagnosis of ASD (Fosse et al. 2004)

16. Language Harris et al. 2006 Semantic Processing Task -Subjects indicated whether a word was +/- (Semantic) or whether a word was in upper/lower case (Perceptual) Results Reduced Broca’s area activation for ASD group during semantic processing

17. Conclusion Autism…. It is complex and complicated Just trying to put the puzzle together one piece at a time!