Wendell Nakamura
LEARNING OBJECTIVES:
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| CASE STUDY: Tommy is an Autistic 6 year old boy. Since starting kindergarten, Tommy has been having difficulty with aggression and behavioral outbursts. His teachers and family need help. He is admitted to the inpatient pediatric unit today so that the healthcare team can complete a detailed assessment and develop a comprehensive treatment plan to support Tommy as he begins school. Read more about Tommy by following this link to his EHR. |
Autism spectrum disorder (ASD) is “a neurological and developmental disorder that affects how people interact with others, communicate, learn, and behave” (National Institute of Mental Health Information Resource Center, n.d., §1). It is considered to be a lifelong and developmental condition because symptoms generally begin to appear around two years of age and persists throughout one’s lifetime. ASD also presents as a broad spectrum of characteristics, from mild to severe and not all people with ASD present with all characteristics. To view a short video that describes a parent’s perspective of ASD, follow this link. To view a short video of a simulation of the perspective of someone with ASD, follow this link.
The global prevalence of people diagnosed with autism spectrum disorder has been estimated to be highest in the Americas and Europe; lowest in the Western Pacific and Southeast Asia (Zeidan et al., 2022).
- Americas (1.32%)
- Europe (1.00%)
- Eastern Mediterranean (0.63%)
- Western Pacific (0.28%)
- Southeast Asia (0.23%)
In many developing countries, prevalence rates appear to be lower because of poorer access to behavioral health services. The diagnostic criteria and tools to measure for ASD were developed with very Western notions of typical behavior. It is important to keep in mind cultural expectations and norms for social interactions must be considered. For example, imaginative play (e.g., make-believe or role-playing) is highly encouraged in Western cultures. In other cultures, play is more functional and literal play (i.e., using objects in the manner in which they are intended) is encouraged; imaginative play in not encouraged. In the use of language, there are some African cultures in which personal pronouns (e.g., I, you, he, she, we, they) are not used and instead, names are used). Additionally, cultural expectations on when a child begins to speak vary widely. In Western cultures, the expectation is that chillren begin speaking around 12 to 18 months of age. In some South Asian cultures, male infants are not expected to begin speaking until age three or four years. Finally, be aware that using eye contact or lack of eye contact is culturally driven; in many cultures, direct eye contact is discouraged, as it shows a sign of disrespect.
If we look at the prevalence rate in the U.S., we see that over time, the prevalence of individuals diagnosed with ASD has steadily increased. This is most likely due to increased awareness and more specific diagnostic criteria to identify children with ASD.
In the U.S., boys are 3.8 times more likely to be diagnosed with ASD than girls (Autism and Developmental Disabilities Monitoring Network, n.d.).
Children from Asian/Pacific Islander and Hispanic families are also more likely to be diagnosed with ASD (Autism and Developmental Disabilities Monitoring Network, n.d.).
A number of comorbidities occur with autism spectrum disorder (Al-Betalgi, 2021; American Occupational Therapy Association, 2022; Kim & Lord, 2013; Sauer et al., 2022):
- Intellectual disabilities
- Learning disabilities
- Genetic disorders (Rett Syndrome, Fragile X Syndrome, Duchenne Muscular Dystrophy)
- Epileptic seizures
- Depressive disorders
- Anxiety disorders
- Obsessive compulsive disorders
- Attention deficit hyperactivity disorders
- Sleep-wake disorders
- Feeding/eating disorders
- Gastrointestinal disorders
- Elimination disorders
Causes of Autism Spectrum Disorder
Etiology/risk factors for autism spectrum disorder falls into two broad categories: genetic and environmental (Betancur & Coleman, 2013; Lydall et al., 2013; Sauer et al., 2022).
Genetic factors:
- There is 70% to 90% parity in identical twins; 0% to 10% parity in fraternal twins
- In 20% to 25% of cases, a genetic mutation is identified
- Maternal (X-chromosome-linked) and paternal (Y-chromosome-linked) microdeletions or microduplications are highly associated with occurrence of ASD
Environmental factors:
- Advancing maternal and paternal age
- Maternal prenatal nutrition (⇅ folic acid [vitamin B9], ↑ mercury, ↑ lead, ↓ zinc)
- Maternal prenatal alcohol and tobacco consumption, especially early in pregnancy
- Proximity to freeways (exposure to hazardous air pollutants such as diesel fuel, mercury, nickel, styrene, beryllium
Clinical Presentation of Autism Spectrum Disorder
The current framework for understanding and diagnosing autism spectrum disorder can be found in the Diagnostic and Statistics Manual of Mental Disorders, Text Revision (DSM-5-TR). People may be diagnosed with ASD if they meet BOTH of the following criteria (National Center on Birth Defects and Developmental Disabilities, n.d.b):
- Persistent deficits in social communication and interaction. Individuals must have deficits in ALL THREE of the following
- Social-emotional reciprocity (turn-taking, experience-sharing)
- Non-verbal communication (eye contact, gestures, facial expressions)
- Developing and maintaining relationships
- Restricted and repetitive behaviors or interests. Individuals must have at least TWO of the following
- Repetitive movements, use of objects, or speech
- Insistence on sameness
- Highly restricted interests
- Hyper- or hypo-reactivity to sensory input
Examples of deficits in social communication and social interaction may include (National Institutes of Mental Health Information Center, n.d.):
- Little or inconsistent eye contact
- Infrequent sharing of emotion, interest, or enjoyment of objects or activities
- Slow to respond to name or other bids for attention
- Talking at length without giving others opportunity to respond
- Facial expressions and gestures that do not match what is being said
- Unusual tone of voice that may be sing-song or monotone
- Having trouble understanding another point of view
- Difficulty sharing in imaginative or reciprocal play
Examples of restrictive or repetitive behaviors include (National Institute of Mental Health Information Center, n.d.):
- Repeating words or phrases (echolalia)
- Difficulty with changes in routine and transitions between activities
- Having overly focused interest (numbers, details, or facts)
- More/less sensitive to sensory input (light, sound, tactile, temperature)
To view a short video that compares typical development versus ASD, follow this link.
FOCUS ON CLINICAL APPLICATION:
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Body Functions & Body Structures of Autism Spectrum Disorder
There is no characteristic brain structure for autism, meaning that no single pattern of structural changes occurs in every individual with autism. There is great variety in the brain structures of people with autism. There are, however, emerging patterns in brain structures between people with and without ASD that are becoming evident. In particular, brain tissue in the cerebellum, parts of the limbic system, and the frontal cortex demonstrate some differences in size, number, and density.
Cerebellum
You will recall from Section 8.1 that the cerebellum arises from the rhombencephalon (hindbrain). The cerebellum’s function is to regulate and refine balance and posture, muscle tone, motor control, language processing, emotional regulation, oculomotor function for visual-spatial relations, and executive functioning (Jimshileishvili & Dididze, 2023). People with ASD generally have decreased size, number, and density of Purkinje cells in the cerebellum. Purkinje cells are large, flat neurons with profuse dendritic branching that secrete the inhibitory neurotransmitter, gamma aminobutyric acid (GABA). These Purkinje cells inhibit specific motor plans within the motor cortex and regulate and refine movement patterns, thereby assisting with error correction. People with ASD have decreased GABA secretion, which results in difficulty with language processing, visual spatial relations, emotional regulation, and executive functioning (Askham, 2020; Bauman & Kemper, 2013; Donovan & Basson, 2017; Roth & Rowell, 2020; Stigler & McDougle, 2013).
Limbic System
You will recall from Section 8.1 that the limbic system is responsible for lower order emotional processing, especially those emotions related to survival (e.g., anger, fear, joy, sadness, disgust, and surprise) and whose facial expressions are generally recognized across cultures (Simic et al., 2021). We focused our earlier discussion of the limbic system on three primary structures: the hippocampus, amygdala, and cingulate gyrus. Alterations in the structures of the limbic system are implicated in characteristic behaviors associated with autism spectrum disorder (Askham, 2020; Morgan et al., 2013; Roth & Rowell, 2020; Stigler & Mcdougle, 2013; Uppal & Hof, 2013; Wright, 2020a, 2020b)
The hippocampus is involved in the formation and storage of the emotional components of associative learning (prediction of behavior and consequences), declarative learning (encoding, storing, and retrieving facts), and memory. In people with ASD, the hippocampus is often enlarged compared to typical people and is responsible for hypervigilance and heightened emotions in people with ASD.
The amygdala is involved in emotional regulation and initiates the sympathetic nervous system (fight-flight response). People with ASD often have an enlarged amygdala, resulting in difficulties with emotional regulation, decreased attention to faces of others (particularly the eye region). This second feature translates to the inability of many people with ASD to read the facial cues of others.
The cingulate gyrus is involved in the integration of emotions, sustaining and shifting attention, and the suppression of a response to non-relevant stimuli. A decreased density of nerons in and reduced volume of the cingulate gyrus in people with ASD is associated with poorer emotional regulation, an inability to shift or sustain attention, and a hypervigilance to stimuli.
Frontal Cortex
You will recall that Broca’s area is usually located in the inferior frontal gyrus of the frontal cortex of the left hemisphere. It is historically associated with the motor aspect of speech production, semantics, phonology, gesture production, sentence grammar and fluidity, and interpretation of the actions of others (Stinnett et al., 2023). A lesion in Broca’s area results in expressive (non-fluid) aphasia (refer back to Section 8.1). You will further recall that Wernicke’s area is located in the superior temporal gyrus of the temporal lobe. Wernicke’s area is associated with speech comprehension (Javed et al., 2023) and lesions in Wernicke’s area typically results in receptive aphasia.
In people with ASD, the size and density of neurons in Broca’s area impacted and there are fewer connections between Broca’s area and Wernicke’s area. As a result, people with ASD tend to have greater challenges with verbal and written expression, reciprocal communication, and understanding and using metaphors (Geggel, 2013; Roth & Rowell, 2020; Uppal & Hof, 2013).
Neurotransmitters
Imbalances in a number of neurotransmitters is also implicated in people with ASD (Blatt, 2013; Marotta et al., 2020; Roth & Rowell, 2020).
- Excitatory:
- Glutamate, which is responsible for learning and memory, is elevated in people with ASD. This results in excitotoxicity, anxiety, perseveration, restlessness, and stereotypic motor behaviors (e.g., hand-flapping, spinning).
- Acetylcholine (ACh), which is responsible for cognitive flexibility, attention, novelty seeking behavior, and memory, is depressed in people with ASD. This results in inflexibility, reduction in ability to sustain attention, and restricted interests.
- Inhibitory:
- Gamma aminobutyric acid (GABA), which is responsible for attention and focus, is depressed in people with ASD. This results in a heightened sense of fear, stress, anxiety, and aggression.
- Modulatory:
- Dopamine, which is responsible for pleasure, motivation, and learning, can be either elevated or depressed in people with ASD. This results in aggressive behavior, and difficulty controlling impulses.
- Serotonin, which is responsible for mood stabilization, well-being, happiness, sleep-wake cycle modulation, and digestive functions, can be either elevated or depressed in people with ASD. This results in restlessness, agitation, and confusion.
Medical Management & Pharmacology
When considering the management of autism spectrum disorder, it is important to keep in mind two very important things. First, people with ASD present in a wide variety of ways, from severe (non-communicative, highly restrictive behaviors, and requiring very substantial support to function) to very mild (advanced communication skills, non-restrictive behavior, and requires little support to function). As with all occupational therapy interventions, approaches to management of symptoms should always be highly tailored to the individual’s occupational performance needs. Secondly, the approach to intervention should be guided by the lens that is most appropriate to the individual’s context. This can range from a biomedical approach in which ASD is seen as a medical condition that needs to be “fixed” to a neurodivergent perspective in which the individual’s social environment needs to be modified to maximize functioning. To that end, there are several means available to people with ASD (National Center on Birth Defects and Developmental Disabilities, n.d.d; Roth & Rowell, 2020).
- Educational Treatment: The Treatment and Education of Autistic and related Communication-handicapped Children (TEACCH®) Autism Program was established by the University of North Carolina, Chapel Hill. It is a program used in the classroom setting that utilizes a child’s strengths in processing visual information to supplement verbal communication through the assistance of external organizational cues such as visual aids, charts, and visible schedules. TEACCH conducts evaluations of children, provides education and training for parents and teachers, and offers advanced certifications for practitioners.
- Behavioral Treatment: Applied Behavior Analysis (ABA Therapy) uses behavior modification and learning theory in a naturalistic setting (such as the home or classroom). It applies principles of operant conditioning (antecedent-behavior-consequence, or a system of reward-reinforcement) to encourage desirable behavior and extinguish unwanted behavior. The Behavior Analyst Certification Board (BACB) offers certification in the use of ABA.
- Pharmacological Treatment: There are several pharmacological options to help manage behaviors associated with ASD. Pharmacological interventions are only intended to manage the symptoms sometimes associated with ASD and are not meant to be used long term. A listing of pharmacological interventions and their effects on relevant neurotransmitters may be found by following this link (LeClerc & Easley, 2015).
- Developmental Treatment: Generally provided in a clinical setting (e.g., outpatient clinic), developmental interventions for people with ASD focuses on improving or regaining key developmental milestones. Speech Language Pathologists (SLPs) address concerns regarding language acquisition and communication. Occupational Therapists (OTs) address concerns regarding self-care and self-management skills, including self-regulation, socialization, and community mobility. Physical Therapists (PTs) address concerns related to acquisition of gross and fine motor skills.
- Social-relational Treatment: (also called Relationship Development Intervention [RDI]) is a parent-led approach that focuses on building social and emotional skills. Because children with some forms of autism struggle with social behavior, RDI helps children with learning from the emotional and subjective experience of others, observing and controlling one’s behaviors to participate in social relationships, using language and non-verbal communication strategies to express curiosity, learning how to adapt and alter plans as circumstances change, putting things into context and solving problems that lack clear solutions, and thinking about past experiences and anticipating future possibilities.
- Psychological Treatment: A psychotherapeutic approach that uses principles of Cognitive Behavior Therapy (CBT) to challenge cognitive distortions and associated behaviors to improve emotional regulation and to develop adaptive coping strategies. It has been shown to effectively reduce depression and anxiety in people with ASD.
- Complementary and Alternative Treatment: The list of complementary and alternative treatment has anecdotally helped some families of people with ASD:
- dietary changes (gluten-free, casein-free)
- herbal supplements
- chiropractic care
- animal therapy
- music therapy
- art therapy
- mindfulness / relaxation therapy
- cannabidiol therapy
- acupuncture/acupressure
- Reiki (energy healing)
- yoga
- hyperbaric oxygen treatment
Summary
Autism spectrum disorder affects people from all parts of the world, regardless of race, income, and cultural background. However, it disproportionally impacts those with poorer maternal healthcare, lower education, and greater exposure to environmental toxins. ASD exists with a number of comorbidities, including intellectual disabilities and psychiatric disorders. People with ASD present over a wide variety of characteristics and the diagnosis of ASD may involve cultural biases. ASD can significantly impact occupational performance and social development. Despite the wide range of clinical presentations, some trends in neuroanatomical differences are becoming evident in the literature. Size and neuronal density of parts of the cerebellum, limbic system, and frontal cortex suggest patterns in the development of ASD. Additionally, various imbalances in neurotransmitters can also impact clinical presentation. Pharmacological interventions are an attempt at correcting neurotransmitter imbalances and educational, behavioral, and developmental approaches are some strategies to maximize functioning in people with ASD.
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