Autism Spectrum Disorder Overview

Autism Spectrum Disorder (ASD)

• ASD is a neurological and developmental disorder
• Begins in childhood and persists throughout life
• Symptoms vary significantly between individuals
• Symptoms intensity varies, ranging from low to high sensitivities
• ASD affects how people act, interact, communicate, and learn

The Autism Spectrum and DSM-5

• Prior to DSM-5, individuals on the autism spectrum were diagnosed differently. Those with higher functioning were classified as having Asperger's syndrome.
• DSM-5 grouped Asperger's syndrome and high-functioning autism into different levels of Autism Spectrum Disorder (ASD)
• ASD diagnosis now uses functional impairment grading (e.g., Requires very substantial support to Requires support)

Clinical Description of ASD

• ASD typically develops during early childhood (often first recognized around the age of 2).
• Development may seem normal up to 12 months, followed by a sudden decline
• No relationship has been confirmed between vaccines and autism
• ASD is characterized by three primary areas of difficulty:
  • Impaired communication
  • Impaired social interaction
  • Restricted behaviors, interests, and activities

Impaired Communication

• Communication difficulties or delays are nearly universal in people with autism
• Language abilities vary widely, from extremely high levels to no speech acquisition.
• Approximately 1/3 of individuals with autism never develop speech.
• Echolalia (repeating others' speech or intonation) is a common communication pattern in ASD.
• Individuals may have specific verbal abilities (e.g., recognizing the alphabet) but struggle with others (e.g., their own name).
• Abstract language (e.g., metaphors, analogies) may be difficult to understand.

Impaired Social Interaction

• Social cognition (thinking about oneself and others in social interactions) may be impaired
• Difficulty with social perceptions may include recognizing the importance of different aspects of events
• Individuals with ASD may have trouble differentiating between social and non-social aspects of events

Theory of Mind

• An impairment in attributing mental states (thoughts, beliefs, and intentions) to oneself or others can affect social interaction
• Affected individuals may struggle to understand another person's internal experience, influencing how they interact with others
• Individuals with low functioning ASD do not typically have theory of mind

Social Interaction (2)

• Affective social competence is how individuals coordinate emotional experiences, message sending and reception and read emotional cues from others
• Individuals with lower functioning ASD are less able to perform these tasks effectively.

Restricted Behavior

• Individuals with ASD show repetitive and seemingly pointless behaviors (stereotypies)

• These stereotypies can also be categorized as stimming, self-stimulation with the aim to soothe sensory experiences, etc.

• Behaviors can be self-injurious

• Prefers familiarity and consistency in routine & environment

ASD is NOT a Weakness

• Individuals with ASD display a wide range of strengths and abilities
• Exceptional talents in math, science, and problem-solving are common in some individuals with ASD

Prevalence of ASD

• Prevalence rates vary across demographics and geographic locations.
• A consistent ratio is 4 males to each female with ASD

Etiology of ASD: Genetics

• ASD is highly heritable
• Monozygotic twins have a higher concordance rate (36-91%) than dizygotic twins (0-5%)
• Genetics contribute significantly to ASD
• Many genes likely play a role, with possibly thousands already identified
• ASD-related genes frequently overlap with genes associated with other neuropsychiatric conditions and intellectual disability
• Vaccines are NOT a cause of autism

Autism and Vaccines

• Studies have shown no link between vaccines and autism.

Autism: Environmental Risk Factors

• Maternal diet (deficient in essential nutrients)
• Folic acid status
• Maternal smoking/drug/alcohol exposure during pregnancy
• Maternal infection during pregnancy
• Maternal low education level
• Air pollutants
• Socioeconomic status
• Advanced maternal/paternal age

The Microbiome

• Gut microbiota encompasses microorganisms (bacteria, viruses, fungi), in the gastrointestinal tract
• The Gut-Brain Axis relates to how the gut microbiome influences brain function
• Symptoms and behaviors associated with autism may be affected by the gut microbiome

Autism and Medical Comorbidities

• Immune dysregulation and gastrointestinal issues are frequently seen in people with ASD
• Post-mortem studies show increased microglial activation and higher levels of inflammatory cytokines in individuals with ASD
• Prevalence of gastrointestinal disorders is higher in people with autism (e.g., diarrhea, constipation, abdominal pain)

Emerging Links to Gut Dysbiota

• Mouse models of ASD and maternal immune activation show impaired social communication and repetitive behaviours
• Disturbances in gut and immune functions are interconnected with ASD
• Gut microbiome composition is dependent on genetics and is affected by external conditions

Neurobiology of Autism

• ASD is not a focal impairment, but rather a complex condition affecting overall brain development and reorganization
• Accelerated brain development in early life (early brain overgrowth), leading to atypical connectivity patterns within the frontal and occipital areas
• Morphological abnormalities at the microstructural level are also observed in autistic individuals

Extreme Male Brain Theory

• Sex-linked variations exist in brain function, like logical/systematic thinking vs. relational empathy
• Autism is an extreme expression of a "normal" male cognitive profile
• Prenatal testosterone exposure may play a role

Prenatal Testosterone

• Prenatal testosterone correlates with several psychological attributes
• Eye contact at 12 months is linked to prenatal testosterone exposure
• Males typically show reduced eye contact, which can be amplified with higher prenatal testosterone levels.
• This reduced eye-contact trait is also part of the spectrum of autism.
• Prenatal testosterone appears to decrease performance on "mind-reading" tasks

The Mirror Neuron System

• Mirror neurons fire during an action and when observing the same action performed by someone else.
• Important for understanding social interactions, and empathy, in healthy individuals.
• Evidence suggests mirror neuron systems are less efficient in people with ASD

Do individuals with ASD have a dysfunctional Mirror Neuron system?

• fMRI studies with tasks requiring observation and imitation suggest reduced mirror neuron system activity in people with ASD.
• This deficit may correlate with the severity of the ASD disorder.

Autism: Current Therapeutic Advances

• Primarily focused on behavior-based therapies (e.g., ABA). No existing pharmaceutical interventions (except for those for other conditions that may be comorbid with ASD).
• Play, social interaction, and communication initiation, that are naturally rewarding, are emphasized during therapy
• ABA uses the principles of learning and emphasizes consequences to shape behavior