Lecture 10: Autism Spectrum Disorder

Autism Spectrum Disorder (ASD)

A complex neurodevelopmental disorder characterized by persistent differences in social communication and social interaction across multiple contexts, with restricted and repetitive behaviours; diagnosed using DSM-5-TR.

DSM-5-TR Diagnostic Use

Used to diagnose ASD and guide interventions.

History of ASD Diagnosis

2013 APA combined autism subtypes into one spectrum; emphasizes persistent differences in social interaction and communication with repetitive interests and behaviours.

Preservation of Sameness

Strong preference for maintaining routines or environments exactly the same; only the child can change them.

Asperger’s Disorder

Milder diagnosis on the autism spectrum (now included in ASD).

Early Infantile Autism / Kanner Syndrome

Term originally used to describe children with early-onset autism; reflects biological withdrawal and sensory sensitivity.

Defining Domains of ASD

(1) Social communication/language difficulties and (2) Restrictive or repetitive patterns of behaviour or interests.

Social Communication Deficits

Difficulties in social-emotional reciprocity, nonverbal communication, and maintaining/understanding relationships.

Repetitive and Restricted Behaviours

Stereotyped motor movements, adherence to routines, fixated interests, and hyper- or hypo-reactivity to sensory input.

Symptom Onset

Must begin in early developmental period and appear across multiple settings.

DSM-5 ASD Severity Levels

Level 3: very substantial support; Level 2: substantial support; Level 1: support required.

DSM-5 ASD Specifiers

With or without intellectual impairment; with or without language impairment; associated with medical/genetic condition; with another neurodevelopmental/mental disorder; with catatonia.

Autism Spectrum Concept

Symptoms, abilities, and characteristics vary widely in type and intensity across individuals.

Ways Autistic Children Differ

Level of intellectual ability, language development, and behavioural changes with age.

Theory of Mind (ToM)

Ability to understand others’ beliefs, feelings, and intentions; autistic individuals typically lack ToM.

Autistic Thinking Style

View social interactions more logically and may not grasp differing perspectives.

Study: Representing Inner Worlds (ToM Study)

Compared autistic, deaf, and hearing children using false-belief tasks; found autistic children had greatest ToM difficulties.

Social Interaction Differences in ASD

Prefer solitary activity, avoid eye contact, show neutral facial expressions, prefer parallel play, focus on mouth instead of whole face, lack joint attention.

Attachment in ASD

Can form normal bonds with caregivers despite social differences.

Communication in ASD

Unusual or delayed development of preverbal communication; inconsistent gestures and vocalizations.

Protoimperative Gestures

Gestures/vocalizations used to express needs.

Protodeclarative Gestures

Gestures/vocalizations directing others’ attention to shared interests—typically absent in autism.

Language Development in ASD

If language develops, it appears before age 5; 30–40% never develop functional speech.

Pronoun Reversal

Repetition of pronouns exactly as heard, without context adjustment.

Pragmatic Language

Use of language in social contexts; often impaired or absent in autism.

Echolalia

Repetition of words or phrases immediately or later after hearing them.

Perseverative Speech

Repetitive speech focused on a single topic or question.

Self-Stimulatory Behaviours (Stimming)

Repetitive body or object movements (e.g., hand-flapping, spinning); can regulate or block sensory input.

Sensory Overresponsivity

Negative or avoidant reactions to sensory stimuli.

Intellectual Differences in ASD

IDD common and predicts later functioning; 70% have comorbid IDD; 40% have two or more other diagnoses.

Splinter Skills

Isolated exceptional talents despite overall impairment.

Self-Injurious Behaviour

Acts of self-harm that may accompany ASD.

Cognitive and Motivational Differences

Differences in social-emotional processing, planning, and attention; poor executive functioning and organization.

Central Coherence

Tendency to perceive information globally; autistic individuals focus on details instead.

Social Motivation Theory

Underlying challenge in seeking and valuing social interaction.

Medical and Physical Characteristics

10% have coexisting medical conditions; 25% seizures; 65% sleep disorders; 50% gastrointestinal symptoms; atypical head growth (small at birth, larger later).

Co-occurring Conditions in ASD

90% have another disorder; 50% have four or more; common ones include IDD, epilepsy, anxiety, learning disorders, and conduct problems.

ASD Prevalence

Affects ~1% of the population (4% boys, 1% girls); occurs across all social and racial groups.

Gender Differences in ASD

3–4x more common in boys; girls more likely to have intellectual impairment; ratio up to 10:1 in high-functioning individuals.

Gender Dysphoria in ASD

6.5% of autistic individuals have gender dysphoria (vs. 3–5% general population).

Developmental Course of ASD

Usually identified around age 2; earliest detection 12–18 months; chronic and lifelong with gradual improvements.

Regression in ASD

About 25% develop typically for first year or more before regression in skills.

Adolescent and Adult ASD Symptoms

Hyperactivity, compulsivity, and self-injury may worsen; later challenges include anxiety, loneliness, and social disadvantage.

Long-Term Outcomes

70% have continuing difficulties that limit independence; IQ and language are strongest predictors of adult outcomes.

Early Signs of ASD (by age)

Delayed social gaze (faces at 12 months instead of birth), delayed eye-gaze following (18 vs. 6–9 months), pointing and symbolic play delayed to 12–18 months.

Genetic Causes of ASD

Strong heritability (70–90% in twins); 15–20% sibling recurrence; 5% linked to chromosomal differences; associated with tuberous sclerosis (25% comorbidity).

Brain Abnormalities in ASD

Structural, functional, and biochemical brain differences; atypical growth patterns.

Prenatal and Developmental Factors

Prenatal/neonatal complications, parental age, and toxin exposure increase risk.

Extreme Male Brain Theory

Proposes ASD represents an exaggerated male cognitive profile—high systemizing, low empathy.

Empathizing–Systemizing Theory

Suggests autism involves excess systemizing and reduced empathizing, reflecting “extreme male” cognitive pattern.

Immunizations and Autism Myth

1998 claim linking MMR vaccine to autism is unsupported by research; no scientific evidence of connection.

Parenting and Autism Myth

“Refrigerator mother” theory (cold parenting causes autism) is false; autism is biologically based.