Autism Spectrum Disorder (ASD) - Fall 2024

Adapted from Disorders of Childhood: Development and Psychopathology, Parritz and Troy 2011 note about language: person first vs identity first Introduction- Autism Spectrum Disorder (ASD)  Autism spectrum disorder (ASD; aka Autism) is a neurological & developmental disorder that...

Adapted from Disorders of Childhood: Development and Psychopathology, Parritz and Troy 2011 note about language: person first vs identity first Introduction- Autism Spectrum Disorder (ASD)  Autism spectrum disorder (ASD; aka Autism) is a neurological & developmental disorder that begins early in childhood & lasts throughout a person's life  Called a "spectrum" disorder b/c people with ASD can have a range of symptoms  Symptoms vary from person to person ASD affects how a  Symptoms can vary in intensity person acts & interacts btw. individuals with others,  i.e., low to high level sensitivities communicates, & learns The Autism Spectrum Up until the DSM5, individuals on the extreme end of the autism spectrum were diagnosed with autistic disorder. Those with higher levels of function were diagnosed with Asperger’s syndrome. In the DSM5, this scheme has changed. Asperger’s has been folded into Autism Spectrum Disorder, which is now given a numerical grade based on the functional impairment. – Grades range from 3 – “Requires very substantial support” to 1 – “Requires support”. Thus high-functioning autism and Asperger’s syndrome are now diagnosed as different levels of Autism Spectrum Disorder. Clinical Description  Autism spectrum disorders typically appear in early childhood, often being first recognized during the second year of life.  Not surprisingly, this is around the same time social behavior is supposed to begin developing.  Parents often report a roughly normal pattern of development up to the 12 month mark, followed by a startling decline in function in following years.  This pattern of development has given rise to many superstitious theories of autism, for example the putative link to vaccines (the delivery of which coincides with sudden declines in function).  The autism spectrum disorders are characterized by three major areas of difficulty: 1. Impaired communication 2. Impaired social interactions 3. Restricted behavior, interests, and activities 1. Impaired Communication  People with autism nearly always have problems or delays in communication.  Language skill can vary widely, with some individuals showing extremely high levels of function.  On average, about 1/3 of people with autism never acquire speech at all.  For those who develop speech, the pattern of communication is often quite unusual.  Echolalia – repeating the speech and intonation of others – is common.  Children may possess an odd combination of verbal abilities, for example knowing the alphabet but not their own name.  Individuals may have an overly literal understanding of language – may have difficulties understanding analogies and metaphors. 2. Impaired Social Interaction  Before we get into the impairments, what is normal?  Social Cognition: how you think about yourself and your social world  Also the knowledge of the perceptions, ideas, and intentions of others  Distinctions between a) What is more and less important ▪ e.g., first words: “ball, kitty, cookie” vs. “wall” b) What is social and nonsocial ▪ People more important  Low functioning kids do not do this  High functioning kids are highly social ▪ Stymied by give and take Social Cognition can be Tested  Theory of Mind  Ability to attribute mental states to others  Others are separate selves, with own points of view and feelings  Low functioning ASD children never get theory of mind Social Interaction (2)  Affective social competence  Coordination of capacities to experience emotion, send emotional messages to others, and read others’ emotional signals ▪ Low functioning kids are unable to do this ▪ High functioning kids lack actual sense or feeling of emotion ▪ Do talk about emotions, but more robotic 3. Restricted behavior  Individuals with autism often exhibit repetitive, apparently pointless behaviors called stereotypies.  Since these behaviors seem to be concerned with sensory self-stimulation, the practice is also called stimming.  Example stereotypies include: rocking, hand flapping, yelling etc.,  These can often be self-injurious.  Autism is associated with an intense preference for the status quo – individuals like things to stay the same.  Ritualistic behaviors may also be apparent, for example lining up one’s blocks in order from largest to smallest.  Clip from Atypical  ASD is NOT a weakness! Despite challenges, ASD is not a weakness Individuals with ASD display a range of strengths & abilities Direction Order Time Individuals with ASD may excel at math or science & have exceptional ability to problem solve  Prevalence of ASD 1 in 66 75% diagnosed by age 8 ttps://www.canada.ca/en/public-health/services/publications/diseases-conditions/autism-spectrum-disorder-children-youth-canada-2018.html Prevalence of ASD Prevalence of ASD not the same across the world o 1 in 597 (Iran), 1 in 294 (Taiwan) One thing that is always consistent is male to female ratio (4:1) Suggests possibility of one of two things: Biology of ASD related to male development ASD manifests itself differently in females? Etiology of ASD: Genetics  Highly heritable  Concordance rate for monozygotic twins is 36-91%; DZ twins 0-5%  Enormous genetic complexity of ASD-related conditions makes it a significant challenge to understand the exact genetic inheritance patterns, with a growing number of genes (close to a thousand) involved ▪ Genetic predisposition combined with an environmental impact ▪ Genes involved in intellectual disability + neuropsychiatric disorder, common pathway genes, ASD-risk genes, multigenic contributions, de novo mutations  Vaccines ruled out as causes of autism Autism and Vaccines Sweden data Danish data Autism: Environmental Risk Factors  Maternal diet: deficient in essential nutrients and fatty acids; affects gut micro immune responses  Folic acid status  Maternal smoking, exposure to alcohol or other drugs during pregnancy  Maternal infection during pregnancy (related to immune activation?)  Low maternal education level  Exposure to air pollutants  Poor socioeconomic status  Advanced maternal and paternal age  No single environmental factor is sufficient to influence the predisposition to ASD combination of factors! The Microbiome  Gut microbiota: microorganisms, bacteria, viruses, protozoa and fungi that are present in the gastrointestinal tract  Gut-Brain Axis: The gut microbiome can influence brain function, potentially affecting behaviors and symptoms associated with autism  Signals to the brain both directly and indirectly (via the immune system) Autism and Medical Comorbities  Immune dysregulation and gastrointestinal disturbances are common among individuals with ASD  Post-mortem brains of ASD patients show increased microglia activation, elevated proinflammatory cytokines  Greater prevalence of gastrointestinal disorders compared to controls, e.g., diarrhea/constipation, abdominal pain, reflex Emerging Links to Gut Dysbiota  Mouse models of ASD (maternal immune activation) results in impaired social communication and stereotyped behaviours, as well as disturbed GI and immune functions!  Microbiota is the intersection between genes and Some symptoms of autism environment  are improved with antibiotics composition depends (Vancomycin) or dietary on genetics, and is adjustments (gluten- and shaped by casein-free diets)! environment Neurobiology of Autism  ASD no longer viewed as a focal impairment in a specific brain region or circuit  Instead, condition resulting from overall brain reorganization, beginning early in development  Overall findings:  Accelerated brain development early in life (“early brain overgrowth”) ▪ results in overall brain under- connectivity (with local over- connectivity in frontal / occipital regions)  Morphological abnormalities at the microstructural level Extreme Male Brain Theory  Simon Baron-Cohen  Sex-linked dimensions of brain functioning  E.g., logical, systematic thinking in men vs. relational empathy in women  Autism is extreme example of “normal” male profile  Exposure to testosterone during development? Prenatal testosterone Numerous subtle psychological traits are correlated with prenatal testosterone. Eye contact at 12 months of age is correlated with prenatal testosterone. – Males naturally make less eye contact Example stimulus from a “mind- than females, and this is exacerbated by reading” task. Can you tell what excess prenatal testosterone. emotion this face is expressing? Interestingly, this is also a trait on the autism spectrum. Prenatal testosterone also seems to reduce performance at “mind-reading” tasks. – These are experimental tasks where children are asked to look at a picture of a person, and guess what that person’s emotional state may be. The mirror neuron system Mirror neurons are neurons that will fire both when an individual performs a certain action, and when they observe that action being performed by someone else. – Mirror neurons can be found in a variety of places throughout the cortex, though they were first discovered in the premotor cortex. Illustration from J.P.J. Pinel, Biopsychology. Allyn & Bacon The mirror neuron system The mirror neuron system may provide a neurobiological basis for social cognition. – Social cognition is the knowledge of the perceptions, ideas, and intentions of others (an ability that is notably absent or deficient in individuals on the autism spectrum). Mirror neurons respond to the understanding of an action, not to some superficial aspect of it. – For example: if you had discovered a mirror neuron that responded to picking up a certain object, it would only fire in response to that object. Moreover, it would fire not only when the action is directly seen, but also when it is implied but hidden (say behind a screen). Mirror neurons have also been found in the cingulate cortex, and the insula. These neurons may play a role in empathy. It seems that many of the deficits seen in autism are precisely those skills that are controlled by mirror neurons. Illustration from Kolb & Wishaw, An Introduction to Brain and Behavior. Do individuals with ASD have a dysfunctional Mirror Neuron system? a) fMRI while observed or imitated facial emotional expressions b) Kids with ASD showed reduced activity in the frontal mirror neuron system (pars opercularis [part of Broca’s area] of inferior frontal gyrus) c) Correlated with severity of disorder ▪ Higher severity – lower activity in MNS Autism: Current Therapeutic Advances  No pharmacotherapy available (only for concurrent disorders)  Mostly, behavioural- based therapies; most common is “Applied Behaviour Analysis” (ABA)  Emphasize play, social interaction, and communication initiation; the “natural consequences” are the reward  https://www.youtube.com/ watch?v=NbVG8lYEsNs  controversial