Source: Abnormal Psychology, University of Florida
Tags: autism spectrum disorder, ASD, social communication deficits, restricted repetitive behaviours, echolalia, savant, Asperger's, DSM-5, pervasive developmental disorder, PDD, neurodevelopmental disorder
Difficulty: Intermediate | Prerequisites: Familiarity with DSM-5 structure, basic neuroscience (brain regions, neurotransmitters), Chapter 10 overview of neurodevelopmental vs. neurocognitive disorders.
Big picture: Autism spectrum disorder is defined by two core domains: deficits in social communication/interaction and restricted, repetitive patterns of behaviour. The DSM-5 collapsed what used to be several separate diagnoses (including Asperger's) into a single spectrum, which remains somewhat controversial. ASD has strong genetic and neurological underpinnings. Treatments do not alter the core features but can meaningfully improve daily functioning, particularly when intensive behavioural intervention starts early.
ASD involves persistent difficulties with social communication and restricted, repetitive behaviours. It is present from early development, has a strong genetic basis, and is now diagnosed as a single spectrum rather than separate categories. Drugs manage secondary symptoms; intensive early behavioural therapy produces the best long-term outcomes.
Autism spectrum disorder (ASD)
A neurodevelopmental disorder characterised by persistent deficits in social communication and social interaction, plus restricted, repetitive patterns of behaviour, interests, or activities. Think of it as a spectrum ranging from individuals who need very substantial support to those who function relatively independently.
Echolalia
Echoing words or phrases that someone else has just said, often with reversed pronouns (using "you" instead of "I"). In simple terms, it is parrot-like repetition of speech heard from others.
Self-stimulatory behaviours
Repetitive motor movements such as hand-flapping, rocking, or spinning objects. These are characteristic of ASD and serve a sensory or self-regulatory function for the individual.
Savant
A rare individual who displays extraordinary talent in a specific area (music, drawing, memory, calculation) despite significant cognitive deficits elsewhere. Think of it as an island of exceptional ability in a sea of impairment.
Pervasive developmental disorders (PDDs)
The DSM-IV category that included autism, Asperger's disorder, and related conditions. Required specific symptom thresholds with onset prior to age 3. Replaced by the single autism spectrum disorder diagnosis in the DSM-5.
Asperger's disorder
Previously classified as a high-functioning form of autism involving deficits in social interaction and repetitive behaviours but without communication deficits. Dropped from the DSM-5 because distinctions were difficult to make reliably and the aetiologies were similar.
Operant conditioning (in ASD treatment)
Behavioural strategies that use structured reinforcement to reduce excessive behaviours and build adaptive skills. In the context of ASD, this often involves highly structured environments with 40+ hours per week of therapy over multiple years.
Criterion A – Social communication and interaction deficits (all three required):
Deficits in social-emotional reciprocity (abnormal social approach, failure of back-and-forth conversation, reduced sharing of interests/emotions, failure to initiate or respond to social interactions).
Deficits in nonverbal communicative behaviours (poor eye contact, limited body language, lack of understanding/use of gestures, absent facial expression).
Deficits in developing, maintaining, and understanding relationships (absence of interest in peers, difficulty adjusting behaviour to social contexts).
Criterion B – Restricted, repetitive behaviours (at least 2 of 4 required):
Stereotyped/repetitive motor movements, use of objects, or speech.
Insistence on sameness, inflexible adherence to routines or ritualised patterns.
Highly restricted, fixated interests abnormal in intensity or focus.
Hyper- or hypo-reactivity to sensory input or unusual interest in sensory aspects of the environment (e.g. fascination with lights/movement, indifference to pain/temperature).
Criterion C: Symptoms present in the early developmental period (though they can be masked by learned strategies later in life).
Criterion D: Symptoms cause clinically significant impairment in social, occupational, or other important areas.
Criterion E: Not better explained by intellectual disability or global developmental delay. ASD and intellectual disability frequently co-occur; for a comorbid diagnosis, social communication must be below the expected developmental level.
Symptoms often appear first in infant-parent interactions: no smiling or cooing in response to caregivers, no initiation of play, resistance to cuddling, minimal eye contact, delayed language development, no interest in other children, no reaction to others' emotions.
About 50% of children with autism do not develop useful speech.
Language, when present, tends to be one-sided, lacks reciprocity, and is monotone.
Echolalia is common, with characteristic pronoun reversal.
Around 50% show at least moderate intellectual disability.
Some score in the average range on tests that do not require language skills.
IQ (along with amount of language learned by age 6) is the best predictor of outcome.
Savant abilities (music, drawing, exceptional memory) occur in rare cases. Temple Grandin is a well-known example of above-average intelligence despite autism.
The DSM-IV used the category of pervasive developmental disorders, with separate diagnoses for autistic disorder and Asperger's disorder.
The DSM-5 merged these into a single autism spectrum disorder because the distinctions were unreliable and the aetiologies overlapped.
This change has been controversial: the DSM-5 criteria capture only an estimated 50–60% of children who would have been diagnosed under the DSM-IV, and only about 25% of those who would have received an Asperger's diagnosis meet the DSM-5 autism criteria.
Genetics
Siblings of individuals with ASD are 50x more likely to develop the disorder.
Concordance rates: 60% for monozygotic twins, 10% for dizygotic twins.
90% of monozygotic co-twins show significant cognitive impairment even when they do not meet full ASD criteria.
Higher-than-average rates of other genetic disorders associated with cognitive impairment (fragile X syndrome, PKU).
No single gene is responsible; abnormalities across several genes contribute.
Neurological
Disruption in the normal development and organisation of the brain.
30% of children with ASD develop seizure disorders by adolescence, pointing to severe neurological dysfunction.
Greater head and brain size in children with ASD.
Affected regions include the cerebellum, cerebrum, amygdala, and possibly hippocampus.
Less activation in the fusiform gyrus, a region involved in facial perception.
Neurological deficits may themselves result from genetic factors.
Neurotransmitters
Abnormal levels of serotonin and dopamine.
Historical note – Leo Kanner
Kanner proposed that autism was caused by a combination of biological factors and poor parenting (cold, distant, uncaring), with symptoms seen as a retreat into fantasy.
This theory has been discredited. Parenting style does not cause autism.
Pharmacological
Drugs do not alter the core features of ASD, but they ease daily functioning.
SSRIs reduce repetitive behaviours and aggression, improve social interactions.
Antipsychotics reduce obsessive/repetitive behaviours, improve self-control.
Naltrexone (opiate receptor blocker) is useful for reducing hyperactivity.
Stimulants improve attention.
Psychosocial/behavioural therapies
Combine behavioural techniques (especially operant conditioning) with structured educational services.
Implemented in highly structured special-needs schools and at home, with parents trained to use techniques consistently.
Key finding: 47% of children given intensive behavioural treatment (40+ hours/week for 2+ years) achieved normal intellectual and educational functioning by age 7, compared with only 2% of those who received institutional care alone.
Early, intensive behavioural intervention is the strongest evidence-based approach for improving outcomes in ASD. The 47% vs. 2% finding is one of the most striking treatment results in the neurodevelopmental literature. Practically, this means that early identification and access to structured services matter enormously.
Students often think Asperger's is still a separate DSM-5 diagnosis. It was absorbed into autism spectrum disorder in the DSM-5, though many people still use the term colloquially.
Students sometimes assume all individuals with ASD have intellectual disability. About half do, and some have average or above-average intelligence.
Students may believe that cold or neglectful parenting causes autism (the "refrigerator mother" theory from Kanner). This has been thoroughly refuted; ASD is rooted in genetics and neurology.
Students occasionally confuse echolalia (repeating others' words) with palilalia (repeating one's own words). Echolalia is the term associated with ASD.
⚠️ Know the two core domains of ASD (social communication deficits + restricted, repetitive behaviours) and the specific criteria under each.
⚠️ Be ready to explain why Asperger's was dropped from the DSM-5 and the controversy around the change (only 50–60% of previously diagnosed children captured; only 25% of former Asperger's cases meet new criteria).
⚠️ The 47% vs. 2% intensive behavioural therapy finding is a likely exam point.
⚠️ Key genetic statistics: siblings 50x risk, MZ concordance 60%, DZ concordance 10%.
⚠️ Understand that medications treat secondary symptoms, not core ASD features.
True or false: Asperger's disorder is still a separate diagnosis in the DSM-5. (False, it was merged into ASD.)
Fill in the blank: The concordance rate for ASD in monozygotic twins is approximately ___%. (60%.)
True or false: About 50% of children with ASD do not develop useful speech. (True.)
Fill in the blank: ________ is the term for echoing words or phrases spoken by others, often with pronoun reversal. (Echolalia.)
True or false: Medications for ASD alter the core features of the disorder. (False, they manage secondary symptoms.)
Q: What are the two fundamental behaviour domains in ASD according to the DSM-5?
A: Deficits in social communication and social interaction, and restricted, repetitive patterns of behaviour, interests, or activities.
Q: Why was the Asperger's diagnosis removed in the DSM-5?
A: Because distinctions between Asperger's and autism were difficult to make reliably, and the conditions shared similar aetiologies. They were merged into a single autism spectrum disorder.
Q: What is the strongest evidence for a genetic basis of ASD?
A: Siblings are 50 times more likely to develop ASD. Monozygotic twin concordance is 60% versus 10% for dizygotic twins. 90% of MZ co-twins show significant cognitive impairment.
Q: Describe the key finding from intensive behavioural treatment research in ASD.
A: 47% of children receiving 40+ hours per week of behavioural therapy for 2+ years achieved normal intellectual and educational functioning by age 7, compared with only 2% of those receiving institutional care.
Q: Which brain region involved in facial perception shows reduced activation in individuals with ASD?
A: The fusiform gyrus.
ASD connects to intellectual disability (frequent comorbidity, shared genetic disorders like fragile X), learning and communication disorders (overlapping language deficits), and the broader discussion of spectrum vs. categorical diagnosis in the DSM. The genetics section ties into behavioural genetics principles. The Kanner theory relates to historical debates about parenting and psychopathology that appear across the course.
Autism spectrum disorder, ASD, autistic disorder, Asperger's syndrome, pervasive developmental disorder, PDD, social communication deficit, restricted repetitive behaviour, echolalia, self-stimulatory behaviour, stimming, savant, fusiform gyrus, serotonin, dopamine, operant conditioning, applied behaviour analysis, ABA, DSM-5 autism criteria, neurodevelopmental disorder, Temple Grandin, Leo Kanner