Autism Spectrum Disorder

8.1.2

ASD

neurological & developmental disorder that impacts interactions, communication, learning, and behavior

severe ASD

• non-communicative

• restrictive, repetitive behavior

• requires substantial support

mild ASD

advanced comm skills

non-restrictive/repetitive behavior

requires support

comorbitites

• intelectual disabiltiies

• learning disabilities

• genetic disorders

  • rett syndrome

  • fragile x syndrome

  • down syndrome

• epileptic seizures

• DD

• AD

• OCD

• ADHD

• sleep-wake disorders

• feeding/eating disorders

• gastrointenstinal disorders

• elimination disorders

Clinical presentation

Persistent deficits in social communication and interaction(3/3)o Social-emotional reciprocity (turn-taking, experience-sharing) o Non-verbal communication (eye contact, gestures, facial expressions) o Developing and maintaining relationships 

Restricted and repetitive behaviors or interests (2/4) o Repetitive movements, use of objects, or speech o Insistence on sameness o Highly restricted interests o Hyper- or hypo-reactivity to sensory input

Common

restrictive or repetitive behaviors

• repeating words or phrases (echolalia)

• difficulty w/changes in routine

• having an overly focused interest

• more/less sensitive to sensory input

gross structures affected by ASD

• cerebellum

• limbic system

  • amygdala

  • hippocampus

  • cingulate cortex

• frontal cortex

cerebellum: purkinje cells

Large, flat neurons with profuse dendritic branching.

 Secretes the inhibitory neurotransmitter, gamma aminobutyric acid (GABA).

 Carries inhibitory output to the cerebral cortex and assists with error correction.

 People with ASD have decreased size, number, and density of Purkinje cells in the cerebellum.

 People with ASD have decreased GABA secretion, resulting in difficulty with language processing, visual spatial relations, emotional regulation, and executive functioning.

 Metencephalon: o Cerebellum:

 Regulates & refines balance & posture

 Regulates muscle tone, motor control, and motor learning

 Contributes to language processing

 Supports visual spatial relations

 Regulates emotional states

 Enhances oculomotor function

 executive function

Temporal lobe:

Limbic system (emotion center) •

Hippocampus •

Emotional processing •

Conversion of short-term memory to longterm memory •

Associative learning (behavior-consequences, stimulus-response) •

Lesions associated with autism spectrum disorder, Alzheimer’s disease, schizophrenia, and ADHD

amygdala

Emotional regulation (esp, fear and anxiety) •

Activates sympathetic nervous system (fightflight response) •

Visual attention to faces (particularly eyes) •

Regulates stimulation of appetite •

Lesions associated with PTSD, autism spectrum disorder, Alzheimer’s disease, anxiety disorders, panic disorder, major depressive disorder, and substance use disorder

cingulate cortex

Processing and regulating emotions •

Reward-based decision-making •

Visual spatial orientation •

Lesions associated with flat affect, lack of empathy, impaired attention, and loss of cognitive flexibility •

Implicated in schizophrenia, obsessive compulsive disorders, depressive disorders, PTSD, and autism spectrum disorder

broca’s area

Size and density of neurons in Broca’s area is impacted in people with ASD.

 Fewer connections between Broca’s and Wernicke’s areas (auditory comprehension) in people with ASD.

 People with ASD tend to have difficulty with: - verbal and written expression - reciprocal communication - understanding and using metaphors

excitatory

o Glutamate (learning & memory) – ↑ in ASD; results in excitotoxicity, anxiety, perseveration, restlessness, stereotypic motor behaviors.

o Acetylcholine (ACh; cognitive flexibility, attention, novelty seeking, memory) – ↓ in ASD; results in inflexibility, reduced sustained attention, restricted interests.

inhibitory

Gamma aminobutyric acid (GABA; attention, focus) – ↓ in ASD; results in fear, stress, anxiety, aggression

modulatory

o Dopamine (pleasure, motivation, learning) – ⇅ in ASD; results in aggressive behavior, difficulty controlling impulses

o Serotonin (mood stabilization, well-being, happiness, sleep, digestion) – ⇅in ASD; results in restlessness, agitation, confusion

biomedical

-education, behavior, pharmacy, developmental, social-relational, psychological, complementary to alternatives

applied behavior analysis (ABA therapy)

o Occurs in a naturalistic setting (e.g., home or classroom)

o Step-wise progression of behavior modification to elicit a desired behavior or response.

o Applies principles of operant conditioning (antecedent, behavior, consequence).

o Uses positive reinforcement to encourage wanted behavior and extinguish unwanted behavior.