Neurodevelopmental Disability and Diversity: Understanding Autism Spectrum Disorder (ASD) and Intellectual Disabilities PDF
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This PDF document excerpt from an educational resource covers intellectual disabilities and autistic spectrum disorder (ASD). The text provides an overview of the characteristics, causes, and interventions related to neurodevelopmental conditions. It also includes self-test questions.
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Okay, I will convert the attached document or image into a structured markdown format as requested. **CHAPTER 17 NEURODEVELOPMENTAL DISABILITY AND DIVERSITY** * What is meant by the term 'congenital disorder' when used in relation to intellectual disability? Can you give some examples of congeni...
Okay, I will convert the attached document or image into a structured markdown format as requested. **CHAPTER 17 NEURODEVELOPMENTAL DISABILITY AND DIVERSITY** * What is meant by the term 'congenital disorder' when used in relation to intellectual disability? Can you give some examples of congenital causes of intellectual disability? * What are the main childhood causes of intellectual disability? * Can intellectual disability be prevented? If so, how? * Can you describe the kinds of training procedures that are used to help individuals with intellectual disabilities acquire self-help and communication skills? * Can you describe some examples of inclusion strategies that have been used in relation to intellectual disability? **SECTION SUMMARY** **17.3 INTELLECTUAL DISABILITIES** * Intellectual disability is a term that covers impairments in both intellectual and adaptive functioning. * Intellectual disability involves significantly below average intellectual functioning, usually defined by a score on a standardised IQ test of below 70. * Modern approaches to defining intellectual disabilities attempt to highlight those factors that might be required to facilitate more adaptive functioning and to draw up accessibility strategies to ensure that such individuals are not excluded or disadvantaged in their education. * Chromosomal disorders such as Down syndrome and fragile X syndrome account for around 25-30% of all diagnosed cases of intellectual disability. * Metabolic disorders that cause intellectual disability are usually carried by a recessive gene and include phenylketonuria (PKU) and Tay-Sachs disease. * Congenital disorders are those that are acquired prior to birth but are not genetically inherited. Congenital causes of intellectual disability include maternal malnutrition, congenital rubella syndrome (CRS), maternal HIV infection, and fetal alcohol syndrome (FAS). * Childhood environmental causes of intellectual disability include childhood accidents (including intentional physical abuse by others), exposure to toxins (such as lead), childhood infections, and poverty and deprivation. * Prevention strategies for intellectual disability include prevention campaigns and screening for such factors as maternal alcohol abuse and genetic risk factors. * Behavioural training procedures can equip sufferers with a range of self-help and adaptive skills, and the application of learning theory in these areas is known as applied behaviour analysis. * Inclusion strategies provide those with intellectual disabilities with access to mainstream educational and occupational opportunities. **17.4 AUTISTIC SPECTRUM DISORDER (ASD)** Some conditions are characterised by a range of different problems in the developmental process, and those that fall under the heading of autistic spectrum disorder (ASD) are usually associated with problems that can affect several areas of development. From early infancy, some children will exhibit a spectrum of developmental impairments and delays that include social and emotional disturbances (e.g., poor social interaction with others), intellectual disabilities (e.g., low IQ), language and communication deficits (e.g., failure to learn to speak or develop language skills), and in severe cases the development of stereotyped or self-injurious behaviour patterns (e.g., hand biting and hair pulling). Prior to DSM-5 there were a number of different ASD diagnostic categories, and these included autistic disorder (autism), Rett's disorder, childhood disintegrative disorder, and Asperger's syndrome. However, DSM-5 has combined these into one single dimensional diagnostic category called autistic spectrum disorder (ASD). *Autistic spectrum disorder (ASD): An umbrella term that refers to all disorders of wide range of severity and disability show autistic-style symptoms across* *** reason for this change was that there was little research evidence that supported the independence of all these different diagnostic categories, and most shared several common features. DSM-5 field studies also supported the validity of the new DSM-5 diagnostic criteria, although these new criteria appear to be reducing the number of individuals who would receive a diagnosis of ASD (Kulage et al., 2019; see also Chapter 2, Section 2.1.3 for a discussion of how changes in the DSM criteria for ASD may affect diagnosis). We discuss the DSM-5 diag- nostic criteria in Section 17.4.2, but first let's look more closely at some of the defining characteristics of individu- als with a diagnosis of ASD. **17.4.1 The Characteristics of Autistic Spectrum Disorder** The early development of some children is so profoundly disturbed that from as young as less than 1 year of age it will become apparent to family and friends that the infant's development is not proceeding normally. The child may seem withdrawn, may have failed to develop normal means of communication, appears uninterested in its surroundings, and may have difficulty learning new skills. Case History 17.2 relates some of the behavioural traits of Adam, a 1-year-old child who was later diagnosed with autistic disorder. Typical of ASDs, Adam shows no interest in his surroundings other than an obsessive interest in a small number of toys, he lacks normal communication skills for his age, and appears withdrawn and unable to learn new responses or skills. He also has temper tantrums when he appears unable to express his needs or has his very detailed play routines disrupted (Case History 17.2). The two central features of ASD are severe impairment in social interaction and in communication. The range of disability caused by problems in social interaction and communication is broad, and many individuals with a diagnosis of ASD are able to function effectively and have successful educa- tional and working careers. However, for others with more severe problems, the level of disability may require lifelong support. **CASE HISTORY 17.2** **AUTISTIC SPECTRUM DISORDER** After Adam's first birthday party, his mother began to pay attention to some characteristics of her son's personality that did not seem to match those of the other children. Unlike other toddlers, Adam was not babbling or forming any word sounds, while others his age were saying 'mama' and 'cake! Adam made no attempt to label people or objects but would just pronounce a few noises which he would utter randomly through the day. At the birthday party and in other situations, Adam seemed uninterested in playing with other children or even being around them socially. He seemed to enjoy everyone singing 'Happy Birthday' to him, but made no attempt to blow the candles out on the cake - even after others modelled the behaviour for him. His parents also noted that Adam had very few interests. He would seek out two or three Disney toys and their corresponding videotapes and that was it. All other games, activities, and toy characters were rejected. If pushed to play with something new, he would sometimes throw intense, unconsolable tantrums. Even the toys he did enjoy were typically not played with in an appropriate manner. Often he would line them up in a row, in the same order, and would not allow them to be removed until he decided he was finished with them. If someone else tried to rearrange the toys he would have a tantrum. As the months went by and he remained unable to express his wants and needs, Adam's tantrums became more frequent. If his mother did not understand his noises and gestures, he would become angry at not getting what he wanted. He would begin to hit his ears with his hands and cry for longer and longer periods of time. Source: Adapted from Gorenstein & Cromer(2004). **Clinical Commentary** From a very early age, Adam exhibited symptoms of the triad of impairments typical of autistic spectrum disorder. He shows (a) no sign of engaging in or enjoying reciprocal social interactions (e.g., the lack of interest in socialising with others at his birthday party), (b) a significant delay in the development of spoken speech (illustrated by his failure to form word sounds, label objects, or express his wants and needs), and (c) a lack of imagination and flexibility of thought (as demonstrated by his inability to use toys in imaginative play and his inflexibly stereotyped behaviour towards these toys). *** **CHAPTER 17 NEURODEVELOPMENTAL DISABILITY AND DIVERSITY** **Impairments of reciprocal social interaction** The impairment in reciprocal social interaction is one of the most marked and sustained features of ASD. Sufferers will exhibit impairment in the use of nonverbal behaviours (e.g., eye contact, appropriate facial expression) and will have difficulty regulating social interaction and communication. In severe cases they will rarely approach others, almost never offer a spontaneous greeting, or make eye contact when meeting or leaving another individual (Hobson & Lee, 1998). In young children, this is often manifested as a clear disinterest in making friends, establishing friendships or any other form of peer com- munication. Particularly striking is the autistic child's apparent inability to understand the intentions or emotions of others and their universal disinterest in what others are doing. This has led some theorists to suggest that children with autistic disorder fail to develop a 'theory of mind, that is they fail to develop an ability to understand the intentions, desires, and beliefs of others, and as a result this makes them unable to understand why other people behave in the way they do. While children with milder forms of the condition may be able to learn what physical features of a person are associated with the expression of an emotion (e.g., that a frown is associated with anger or disapproval), they are often una- ble to explain why someone is expressing a particular emotion (Capps, Losh, & Thurber, 2000). **Impairments in communication** There is often a prominent delay in the development of spoken language, and in those that do learn to speak there can be an inability to sustain a conversation. When speech does develop, it may fail to follow the normal rules of pitch, intonation, or stress, and a child's speech may sound monotonous and disinterested. Grammatical structures are often immature and more than half of those diagnosed with autistic disorder fail to speak at all but may utter a range of noises and screams that are often unrelated to attempts to communicate. Some individuals exhibit what is known as echolalia, which is immediate imitation of words or sounds they have just heard (e.g., if asked "Do you want a drink?" the child will reply "Do you want a drink?"). Others that do develop language may only be able to communicate in a limited way and may exhibit oddities in grammar and articulation. For instance, some exhibit pronoun reversal in which they refer to themselves as 'he','she', or 'you', and this is a feature of speech that is highly resistant to change (Tramonta & Stimbert, 1970). An autistic child's ability to learn language is a good indicator of prognosis. Those that have learned meaningful speech by age 5 years are the ones that are most likely to benefit from subsequent treatment (Werry, 1996; Kobayashi, Murata, & Yoshinaga, 1992). **Impairments in imagination and flexibility of thought** One feature of many individuals with ASD is that they often display restricted, repetitive, and stereotyped patterns of behaviour and interests. This can manifest in childhood as a specific and detailed interest in only a small number of toys. Like Adam in Case History 17.2, they may line up the same set of toys in exactly the same way time after time and become very distressed if their routine is disrupted or if they are not allowed to com- plete the routine. There appears to be a need to retain 'sameness' in all their experiences, and an autistic child may become extremely distressed if the furniture in a room is changed around or they travel on a different route to school one day. Children with ASD will often form strong attachments to inanimate objects such as keys, rocks, mechanical objects, or objects with particu- lar types of tactile characteristics (such as the smooth- surfaced dice described in George's Story at the beginning of this chapter). However, when they do play with indi- vidual objects, such as a toy car, they rarely indulge in symbolic play (e.g., by moving the car along the floor as if it were travelling somewhere), but instead will usually explore the tactile features of the toy in a stereotyped manner (e.g., by simply rotating the car in their hands for long periods of time). A further common characteristic of ASD in childhood is the appearance of stereotyped body movements, and these can include hand clapping, finger snapping, rocking, dipping, and swaying. These patterns of behaviour often appear to be self-stimulatory in nature and can often become so intense and severe that they may cause the individual physical injury, such as stereotyped hand and finger biting, head banging, hair pulling, and scratching. **Intellectual deficits** In addition to these main symptoms, it is estimated that around 70% of individuals with a diagnosis of ASD also have some level of intellectual disability, and the ins ing 30% may have some other form of disability such as a speech or behaviour disability or a cognitive impairment (e.g., a working memory problem) (Srivastava & Schwartz, 2014). However, the nature of the intellectual deficits in children with ASD is often different to those with a primary diagnosis of intellectual disability (see Section 17.3). Individuals with a diagnosis of ASD will usually perform much better on tests of visuospatial ability than tests of social understanding or verbal ability. Thus, they are much better at finding hidden figures in drawings, assembling disassembled objects, and match- ing designs in block-design tests (Rutter, 1983). However, *** **TABLE 17.8 Summary: DSM-5 Diagnostic Criteria for Autism Spectrum Disorder** | | | :------------------------------------------------------------------------------------------------------------------ | | **Ongoing deficits in social activities as marked by the following:** | | Social situation deficits - for example, abnormal social approach or failure to initiate or respond to social situation | | Nonverbal communication behaviour deficits - for example, abnormalities in eye contact or poorly | | integrated verbal and nonverbal communication | | Inability to develop, maintain, or understand relationships | | **Restricted and repetitive patterns of behaviour, interest, or activity, as marked by at least two of the following:** | | Repetitive motor movements, use of objects or speech | | Inflexibility and strong adherence to routine | | Abnormally intense fixated interests | | Hyper- or hyporeactivity to sensory input or unusual | | interest in sensory aspects of the environment | | Symptoms start in early development | | Symptoms cause significant impairment in important areas of functioning | | Symptoms are not better accounted for by intellectual disability or global development delay | *** high-functioning autism, and at the high-functioning end over a range of disabilities from severe to relatively mild symptoms that may be characteristic of autism. Similarly, of the spectrum it is often hard to distinguish those diagnosis is complicated by the fact that (a) behaviour patterns may change with age, (b) symptoms may be manifested with varying degrees of intellectual disability, and (c) ASDs are often comorbid with other problems such as ADHD and epilepsy. **17.4.3 The Prevalence of Autistic Spectrum Disorder** The latest studies of ASD in adults in the UK indicate a prevalence rate of around 1.1% indicating that over 700,000 people in the UK may be potentially diagnosable with ASD (Brughas et al., 2016). In childhood, a significant majority of those diagnosed with ASD are boys with a frequently cited ratio of 4: 1 (Halladay et al., 2015), and autism appears to occur equally in all socio-eco- nomic classes and racial groups (Fombonne, 2002). Epidemiological surveys of ASD suggest that the preva- cantly over the last 2-3 decades, and the US Centers for lence rate of the disorder has been increasing signifi- Disease Control and Prevention (CDC) estimates that in 2000 1 in 150 children in the US were diagnosed with rising to 1 in 54 (CDC, 2019). The reasons for this are unclear, although one possible cause may be the expansion of the criteria ASD, but by 2016 this figure had risen to 1 in 54 *** CHAPTER 17 NEURODEVELOPMENTAL DISABILITY AND DIVERSITY for diagnosis of ASD in DSM-IV that was published in 1994, whereas some others suspect this may be a real increase in incidence resulting from an increase in the prevalence of those factors that cause ASD (e.g., Blaxill, Baskin, & Spitzer, 2003). However, it is clear that the changes to the diagnostic criteria introduced in DSM-5 in 2013 have begun to cause a reduction in prevalence rates for ASD, and studies comparing DSM-5 and DSM-IV-TR diagnostic criteria indicate a reduction of up to 9% in the number of individuals diagnosed with ASD under DSM-5 compared with DSM-IV-TR (Huerta, Bishop, Duncan, Hus, & Lord, 2012; Wilson et al., 2013; see Kulage et al., 2019, for more recent figures). **17.4.4 The Aetiology of Autistic Spectrum Disorder** In the 1960s, it was believed that autistic behaviour was caused by cold or rejecting parenting (e.g., Bettelheim, 1967) a view that simply added to the distress of parents already having to cope with a child with severe behavioural problems. However, subsequent stud-ies have systematically failed to uphold this view and have confirmed that the parents of autistic children are no dif-ferent in their parenting skills to those of nonautistic children (Cox, Rutter, Newman, & Bartak, 1975; Cantwell, Baker, & Rutter, 1978). Nevertheless, the causes of ASD are still relatively poorly understood, but it is becoming clear that there is a significant genetic element. However, in individual cases there is also likely to be a contribution from environmental factors as well, such as perinatal risk factors (e.g., maternal infections during pregnancy), and the various combinations of genetics and environmental risk factors may be the reason why ASD varies so much in its symptomatology and severity. **Biological causes** *** There had been evidence available for factors In particul some time that the social and language deficits and psy- chological problems reminiscent orASD often had a ram- Hy history (Folstein & Rutter, 1988; Piven & Palmer, 1999), there is evidence for a strong familial aggre- gation of autistic symptoms, as demonstrated in studies of sibling reoccurrence risk (i.e., studies investigating the probability of developing autism given that an individual's sibling is autistic). These studies have estimated that the rate of autism in the sibling of someone with autism ranges between 2 and 14% (Bailey, Phillips, & Rutter, 1996; Jorde et al., 1990), which is significantly higher than the prevalence rate found in the general population. ASD also appears to co-occur with several known genetic disorders phenylketonuria, fragile X syndrome, and such as tuberous sclerosis (Smalley, 1998; Reiss & Freund, 1990), implying a genetic link in its aetiology. There are also familial links between ASD and other psychological prob- lems. For instance, affective disorders are almost three times more common in the parents of autism sufferers than in the parents of children suffering from tuberous sclerosis or epilepsy. While we might expect that having a child with a disability might precipitate such psychological problems, a majority of parents of autistic children devel- oped their affective disorder before the birth of the child (Bailey, Phillips, & Rutter, 1996). *** Many twin studies have confirmed this genetic component to ASD. In studies comparing concordance rates in MZ and DZ twins, Folstein & Rutter (1977) found concordance in 4 out of 11 MZ twins but none in DZ twins. Subsequent twin studies have found concord- ance rates of between 60 and 91% for MZ twins and between 0 and 20% for DZ twins (Rutter et al., 1990; Bailey et al., 1995; Steffenberg et al., 1989; Lichtenstein, Carlstrom, Ramstam, Gillberg, & Anckarsater, 2010), and a recent meta-analysis of twin studies has indicated that the heritability level of ASD is substantial, at between 64 and 91% (Tick, Bolton, Happe, Rutter, & Rijsdijk, 2016). In addition, twin studies have also demonstrated that each of the symptom components of autistic disorder-social impairments, communication impairments, and restricted repetitive behaviours-all individually show high levels of heritability (Ronald, Happe, Price, Baron-Cohen, & Plomin, 2006). Molecular genetics have implicated over 100 genes as risk factors for ASD (Satterstrom et al., 2020). Most of these affect the development of brain synapses or regulate other genes, and while some have a broad effect on early development, others are more specific to the symptoms of ASD. Figure 17.2 provides an overview of some of the mechanisms by which these gene effects are moderated. These include (a) abnormalities resulting from gene copy number variations (CNVs), (b) epigenetics, in which perinatal or early development experiences may modulate the expression of genes (e.g., Wong et al., 2014), (c) double-hit mutations (abnormalities resulting from rearrangements sex-linked modifiers (i.e., in two particular genes), and (d) sex-linked modifiers (i.e., sex-linked genes that may make males more susceptible to ASD) (Rylaarsdam & Guemez-Gamboa, 2019). Most this evidence strongly indicates that ASD is a complex inherited condition that may involve a range of different genetic influences affecting symptom expression and severity, including several different gene CNVs (Freitag, Staal, Klauck, Duketis, & Waltes, 2010). *** We noted in our discussion ofintel- lectual disabilities, that perinatal factors may play a sig- nificant role in determining intellectual impairment and the same may be true in the case of ASD. A range of birth **Biological causes** *** **FIGURE 17.2 Genetic modifiers in autism spectrum disorder.** Autism spectrum disorder is estimated to be between 64 and 91% inherited (Tick, Bolton, Happe, Rutter, & Rijsdijk, 2016). However, both genetic and nongenetic factors modulate the influence of risk genes, resulting in a highly heterogeneous set of symptoms. Examples of genetic modulators include CNV (abnormalities resulting from gene copy number variations), epigenetics (e.g., maternal complications during pregnancy may influence gene expression), and double-hit mutations (where abnormalities result from rearrangements in two particular genes). Examples of nongenetic modifiers include environmental exposures (e.g., maternal tobacco smoking) and sex-linked modifiers (e.g., sex-linked factors that may protect females from ASD or make males more susceptible to ASD). From Rylaarsdam & Guemez-Gamboa, 2019 *** complications and pre-natal factors have been identified as risk or drugs such as thalidomide and factors in the development of ASD, and these include maternal infections, such as maternal rubella during pregnancy (Chess, Fernandez, & Korn, 1978), intrauterine exposure to drugs as thalidomide and valproate (Stromland, Nordin, Miller, Akerstrom, & Gillberg, 1994; Williams et al., 2001), maternal bleeding after the first trimester of pregnancy (Tsai, 1987), and depressed maternal immune functioning during pregnancy (Tsai & Ghaziuddin, 1997). However, many of these risk factors have been identified only in individual case reports, and they probably account for a very small percentage of cases of ASD (Fombonne, 2002; Muhle, Trentacoste, & Rapin, 2004). For example, recent studies suggest that congenital rubella infection has been found largely because of the near eradication of the disease in Western countries (Fombonne, 1999; however, rubella may still be a cause of autism, Hutton, 2016). Some studies a link between ASD, infammatory bowel disease. also claim the administration of the measles, mumps, and rubella (MMR) vaccine (Wakefield et al., 1998). This claim caused some controversy in the UK at the time because it led to many parents refusing to have their children immunised with the vaccine, and so put them at significant risk for these infections (see Activity Box 17.1). However, subsequent studies have failed to corroborate an association between administration of MMR and autism (e.g., Madsen et al., 2002; Hviid, Hansen, Frisch, & Melbye, 2019). In addition, recent studies have also failed to find any between infectious diseases the of autism . Rosen, Yoshida, & Crohn (2007) early children autism subsequent of no Brain Function brain abnormalities in autism progress during ditterent developmental stages They have confirmed that individuals with autism have abnormall ties in a nun ber of braln regions, including the fromal lobes limbic system cerebellum, and basal ganglia (Sokol Edwards-Brown, 2004), and they also confirm nat autistic individuals have brain size and significantly poorer neutral connectivity then non suffer McAlanor 82555 already allu the Fact that indivi **Brain Function** fact that individuals diagnosed with autisn may lack a theory of mind the to attibute mental states to others or understand the intentions of other Section 17.44, and studies indicate that this is duced ctivation. for brain children with subsequent diagnoses autism had overall Infe. *** CHAPTER 17 NEURODEVELOPMENTAL DISABILITY AND DIVERSITY but brain size increases significantly between 12 and 24 months, and brain size at 24 months is positively cor- related with autism symptoms (Hazlett et al., 2017). A brain that is growing at a faster rate than normal may mean that neurone connections are not being made selectively, and this may affect the functionality in impor- tant parts of the brain such as the frontal and temporal lobes. Taken together, these sources of evidence indicate that individuals with ASD exhibit abnormalities in a umber of ditterent brain areas These brain areas are detes anatomical 2- structural developmental ab nor malities, as well as functional abnormalities an they d the Cognitive disorder alse extubit EEO pattern and any seizures cognitive factors Depending on the seventy of symptoms individ Als with ASD often have problems allending to and understanding the world around them Most notably They have difficulty with normal social functunning in severe cases They may be withdrawn and unresponsive while less severe cases may exhibit difficulty in reciprecal social Interaction including experiencing problems in Commuruation and in understanding the intentions and These deficits in social skills are as *** RESEARCH METHODS BOX 17.1 sally with autism Baron Cohen Lestie Inthis ure two dolls used out the story **FIGURE 17.1 THE SALLY-ANN FALSE BELIEF TASK** *** **THE SALLY-ANN FALSE BELIEF TASK** *** CHAPTER 17 NEURODEVELOPMENTAL DISABILITY AND DIVERSITY Some researchers sally with autism individuals with ASD will undoubtedly have difficulty indulging in sym- more sallerl **The empathising-systematising theory** *** *Note: There are images and diagrams accompanying the tables and questions that I am unable to reproduce in this text-only format.* **COMPENSATORY STRATEGIES FOR EVERYDAY SOCIAL INTERACTION** *** **Summary of support & interventions for individuals with autistic Spectrum disorder** * Basic behavioural training methods have proven to be effective at promoting a range of self-help, social, and communicative skills in those most severely affected and this has supplemented the adoption of parent training programs that extends the range of individuals necessary for succesful interventions * Drugs are commonly used primarily to control self Injurious challenging, * ASD is genetically determined **Summary of support & interventions for individuals with autistic Spectrum disorder** *** This structured markdown format should be more readable and easier to navigate. Let me know if you need further assistance.