Autism Flashcards
What early traits did Kanner and Asperger observe in children with autism?
Preference for aloneness, insistence on sameness, stereotyped behaviours, and in some cases, remarkable memory for numbers or tunes.
How did the DSM V change the classification of autism-related disorders?
- Autism
- Asperger’s syndrome
- Childhood disintegrative disorder
- PDD-NOS
Merged into a single category called ASD.
What are the two main domains of impairment used to diagnose ASD in the DSM V?
(1) Social communication and interaction deficits.
(2) Restricted, repetitive patterns of behaviour, interests, or activities.
What are the three main types of social communication and interaction deficits in ASD?
- Deficits in social-emotional reciprocity
- Deficits in nonverbal communication
- Deficits in developing, maintaining, and understanding relationships
Give an example of a deficit in social-emotional reciprocity in ASD.
Failure of normal back-and-forth conversation or reduced sharing of interests and emotions.
Give an example of a deficit in nonverbal communication in ASD.
Poor eye contact, unusual gestures, or lack of facial expressions.
Give an example of a deficit in developing and maintaining relationships in ASD.
Difficulty adjusting behavior to social context or lack of interest in peers.
What are the four main types of restricted and repetitive behaviors in ASD?
- Stereotyped or repetitive movements, speech, or use of objects
- Insistence on sameness and inflexible routines
- Highly restricted, fixated interests
- Hyper- or hyporeactivity to sensory input
Give an example of a stereotyped or repetitive behavior in ASD.
Lining up toys, echolalia, or using idiosyncratic phrases.
Give an example of insistence on sameness in ASD.
Distress at small changes or needing to take the same route every day.
Give an example of a highly restricted, fixated interest in ASD.
Strong attachment to unusual objects or an intense focus on one topic.
Give an example of hyper- or hyporeactivity to sensory input in ASD.
Indifference to pain, sensitivity to specific sounds, or fascination with lights.
When must ASD symptoms be present to qualify for diagnosis? What is required for ASD symptoms to meet diagnostic criteria?
- In early childhood (but may not fully manifest until social demands exceed capacity)
- They must limit and impair everyday functioning.
Can ASD be explained by intellectual disability (ID) alone?
No, but ASD and ID frequently co-occur. Social communication should be below the expected developmental level for a comorbid diagnosis.
What disorder should be considered if a person has social communication deficits but no restricted or repetitive behaviors? What are signs of this disorder? What is an example?
- Social (pragmatic) communication disorder.
- Difficulty adjusting communication to context, understanding indirect language, and following conversation rules.
- Speaking the same way in class and on the playground.
Give an example of a problem with understanding indirect language in social (pragmatic) communication disorder.
Misunderstanding idioms, humour, or metaphors.
How common is ASD? Is Autism more common in females or males, and by how much?
- ASD affects 1 in 36 individuals.
- 4 times more common in males than females.
What are some possible reasons for the increased prevalence of autism?
- Better awareness
- Wider diagnostic criteria
- Unidentified environmental risk factors
What are the three main behavioral co-morbidities in autism?
- Hyperactivity and attention abnormalities
- Anxiety
- Intellectual disability
What is the connection between ADHD and ASD?
- ADHD is an exclusionary criterion for ASD.
- Despite this, ASD and ADHD have overlapping behavioural, cognitive, and neurobiological deficits.
What ADHD-like symptoms are common in ASD?
- Hyperactivity
- Inattention
- Impulsivity
What types of verbal outbursts are common in ASD?
- Tantrums
- Slamming doors
- Tipping over tables
- Banging head with fists
How common is anxiety in individuals with ASD?
Anxiety disorders affect between 47% and 84% of people with ASD.
What features of ASD are linked to anxiety?
- Insistence on sameness
- Fixed behaviors and routines
Why might individuals with ASD struggle to manage anxiety?
- Lack of coping skills
- Poor ability to cognitively appraise stressful situations
What types of anxiety disorders overlap with ASD?
- Social phobia
- Generalized anxiety disorder
- OCD
What percentage of children with ASD have average to above-average intellectual ability? How do children with ASD typically perform on visual skill tests?
- About 44%
- They often perform well on visual skill tests.
What are the key differences between autism and intellectual disability?
- Children with intellectual disability can socially interact with others according to their mental age.
- Verbal communication is less impaired in intellectual disability.
What are the five main neurological co-morbidities in autism?
- Sensory integration abnormalities
- Seizures
- Fragile X Syndrome
- Tuberous sclerosis
- Motoric disturbance
What types of sensory integration abnormalities are common in ASD?
- Increased sensitivity to acoustic and tactile stimuli.
- Insensitivity to extreme cold or pain.
What types of seizures are common in ASD?
- generalized tonic-clonic
- partial seizures
Seizures usually start in ASD from the ages of 8-10 years.
What factors increase the risk of developing ASD in individuals with tuberous sclerosis?
- Temporal lobe tubers
- Temporal lobe epilepsy
- Seizures
What types of motor skill problems are common in ASD?
- Difficulty acquiring motor skills and motor dexterity
- Greater difficulty walking along a straight line
- Variable stride length and duration
- Less coordination and reduced smoothness of movement
What neurological condition is the motor disturbance in ASD similar to?
Cerebellar ataxia.
What does the presence of neurological problems in ASD suggest about its cause?
It supports a biological (neural) basis for ASD.
What type of cognitive deficits are believed to underlie social abnormalities in ASD? (Psychological Theories of Autism)
Deficits in understanding social and emotional cues.
What cognitive theory explains the social difficulties in ASD?
The theory of mind or mentalizing deficit.
-> This means the ability to predict and explain others behaviour based on their mental states (e.g., beliefs, desires, intentions)
What types of mental states do autistic children have difficulty understanding?
- Beliefs
- Wishes
- Desires
- Intentions
- Pretending
What is a first-order vs. second-order representation in theory of mind?
- First-order: “I think he thinks…”
- Second-order: “I think he thinks she thinks…”
How does a deficit in theory of mind affect social relationships in ASD?
- Difficulty forming and maintaining social relationships.
- Reduced ability to empathize.
What is an example of how theory of mind deficits affect empathy?
An autistic child may assume that if they are happy, others must be happy too.
What secondary issues can arise from theory of mind deficits?
- Anxiety
- Ritualistic behavior
- Inattention
- Interest in objects rather than people.
What type of disorder is autism?
Autism is a severe neurodevelopmental disorder. The causes are still largely unknown, but substantial evidence supports genetic involvement.
What are some genetic disorders commonly associated with autism?
- Tuberous sclerosis
- FXS
- Down Syndrome
- Neurofibromatosis Type I
What do twin studies reveal about autism concordance rates?
- Monozygotic twins: 60-90% concordance rate.
- Dizygotic twins: 10% concordance rate.
What inheritance pattern does autism follow?
Polygenic inheritance - no single gene or variant is necessary or sufficient to express the phenotype.
What other disorders share a polygenic architecture with autism?
- SCZ
- Depression
- Intellectual disability
What chromosomal regions have been identified in autism-susceptibility loci from whole-genome scans?
- Chromosome 2q
- Chromosome 7q
- Chromosome 17q
What genetic studies have implicated over 100 genes in autism?
- GWAS
- CNV (Copy Number Variation) Studies
Which genes involved in excitatory and inhibitory synaptic functions are linked to autism?
- NLGN3 and NLGN4 (neuroligins)
- NRXN1 (neurexin)
- SHANK3 (postsynaptic density protein)
- CNTNAP2 (contactin-associated protein)
How do genes involved in autism affect neurotransmission?
They cause an imbalance between excitatory and inhibitory (E-I) neurotransmission in the brain.
What complex stabilizes glutamate receptors at excitatory synapses in the CNS?
Neurexin–Neuroligin–Shank complex with PSD95
What have transgenic mouse models with mutations in NRXN1, NLGN3, SHANK3, and CNTNAP2 shown?
Behavioral and neural phenotypes resembling autism.
What behavioral phenotypes were observed in macaque monkeys with embryonic CRISPR-mediated SHANK3 mutation?
- Stereotyped repetitive behaviours
- Reduced social behaviour
- Longer latency to sleep
What environmental factors linked to schizophrenia also increase autism risk?
- Maternal infections during pregnancy (bacterial or viral)
- 30% increase in autism risk with any inpatient diagnosis of infection during pregnancy (elevated risk in all trimesters/higher risk of autism with intellectual disability than without)
What prenatal insults have also been linked to autism?
- Obstetric complications
- Intrauterine exposure to teratogenic drugs.
What was the controversy around the MMR (measles–mumps–rubella) vaccine and autism?
- Six of 12 children with autism showed behavioral changes within 2 weeks of immunization.
- The part of the MMR vaccine blamed was: Thimerosal (a mercury-based preservative)
- This vaccine is not used anymore.
- There is no evidence linking NMR to autism.
What are the key brain regions implicated in autism?
- Frontal Cortex
- Amygdala and social brain circuit
- Cerebellum
- Brainstem nuclei
- Hippocampal formation
What does brain volume look like in autistic individuals at different ages?
- Adolescents/adults -> decreased brain volume.
- Young cases -> Early brain overgrowth (early to late childhood)
What study linked cortical surface expansion to brain overgrowth in autism?
- 6-12 months -> Hyperexpansion of cortical surface area in high-risk infants.
- 12-24 months -> Brain volume overgrowth in those diagnosed with autism at 24 months.
Suggests over-proliferation of cortical progenitor cells leads to:
- Altered connectivity
- Reduced synaptic pruning
- Excitatory (glutamate) and inhibitory (GABA) imbalance.
- Autistic deficits.
What pro-inflammatory cytokines are elevated in autistic brains?
IL-1β, IL-6, IL-17, TNF-α
What cytokines are increased in plasma samples of autistic children (ages 2–5)?
IL-1β, IL-6, IL-8
What neuroimmune cell type may be altered in autism?
Microglia → Some studies show increased number or activation profile
How does reduced synaptic pruning relate to autism?
- Cx3cr1 knockout mice (receptor for chemokine fractalkine Cx3cl1):
- Reduced synaptic pruning in hippocampus
- ASD-related behaviors (e.g., decreased social interaction)
What serotonin-related findings are linked to autism?
- Lack of 5-HT synthesis peak in autistic infants.
- Reduced 5-HT2A binding in cerebral cortex.
- Elevated serotonin levels in platelets (blood studies)
- SSRs may improve social behaviour and reduce aggression in adults, but mixed results in children.
How are glutamate and GABA implicated in autism?
- Glutamate
- Role in cortical development
- Some GluR genes associated with autism - GABA
- Improvement for brain development
- Reduced GABA receptor system in autistic brain tissues
What evidence links dopamine to autism?
- Increased CSF homovanillic acid (HVA) in autism.
- HVA = Major metabolite of dopamine → Increased HVA suggests increased dopamine turnover/activity in the brain - Risperidone (at low doses): Reduces aggression, self-injury, and tantrums
- Risperidone is a dopamine (D2) receptor antagonist → It blocks dopamine receptors, reducing excessive dopamine signaling → Helps regulate behavior and reduce irritability in autism
What are oxytocin and vasopressin, and how are they linked to autism?
- Oxytocin and arginine vasopressin are similar neuropeptides produced in the hypothalamus.
- Evidence from animal and human studies suggests they play a role in social behavior and may be involved in autism.
What is the reproductive role of oxytocin?
- Stimulates uterine contractions during labor.
- Induces milk production during breastfeeding.
What are the brain functions of oxytocin?
- Present in brain regions involved in reward and social behavior: Nucleus accumbens, Prelimbic cortex.
- Important for social cues, social attachment, and bonding.
How do vole studies link oxytocin and vasopressin to social bonding?
- Prairie voles (socially monogamous):
- Form pair bonds and raise offspring together.
- High oxytocin receptor density in the nucleus accumbens = stronger social bonding. - Montane and meadow voles (promiscuous):
- Do not form pair bonds or engage in parenting.
- Lower oxytocin receptor density in the nucleus accumbens.
What evidence from oxytocin knock-out mice supports oxytocin’s role in social behavior?
- OT knock-out mice fail to recognize familiar individuals after repeated social exposure.
- They have normal olfactory and spatial learning.
- Oxytocin treatment restores social recognition.
How does oxytocin influence social behavior in humans?
- Increases sensitivity to social cues
- Improves: Trust, Cooperation, Social perceptiveness (e.g., eye contact, emotional recognition)
- “Reading the Mind in the Eyes Test” (RMET): OT increases emotional recognition from facial expressions.
What did oxytocin studies show in young ASD cases?
Single intranasal oxytocin:
- Increased activity in brain reward circuits (striatum, nucleus accumbens).
- Increased activity in brain regions involved in social attention and social cognition (during eye vs vehicle stimuli).
- No improvement in task performance.
Are oxytocin levels altered in ASD children and adults?
- Reduced oxytocin levels in plasma, saliva, and CSF in ASD children (not adults).
- Oxytocin levels correlate with ASD symptom severity in children.
What do clinical trials say about oxytocin treatment for autism?
- Mixed results:
- Benefit seen in ASD children with low baseline oxytocin levels.
- Other studies show no significant benefit in reducing ASD symptoms. - Effects depend on:
- Baseline oxytocin levels
- Dosage
- Context
How might oxytocin and vasopressin influence autism symptoms?
- Oxytocin may enhance social bonding and recognition.
- Vasopressin may also influence social behavior through its action on the reward system and social circuitry.
