出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2019/08/12 16:31:02」(JST)
| Autism spectrum | |
|---|---|
| Other names | Autism spectrum disorder (ASD), autism spectrum condition (ASC)[1] |
| Repetitively stacking or lining up objects is associated with autism. | |
| Specialty | Psychiatry |
| Symptoms | Problems with communication, social interaction, restricted interests, repetitive behavior[2] |
| Complications | Social isolation, employment problems, family stress, bullying[3] |
| Usual onset | By the age of 3 years[4] |
| Risk factors | Advanced parental age, exposure to valproate during pregnancy, low birth weight[2] |
| Diagnostic method | Based on symptoms[5] |
| Differential diagnosis | Intellectual disability, Rett syndrome, ADHD, selective mutism, childhood-onset schizophrenia[2] |
| Treatment | Behavioral therapy,[6] psychotropic medication[7] |
| Frequency | 1% of people[2] (62.2 million 2015)[8] |
Autism spectrum, also known as autism spectrum disorder (ASD), is a range of mental disorders of the neurodevelopmental type. It includes autism and Asperger syndrome. Individuals on the spectrum often experience difficulties with social communication and interaction; and restricted, repetitive patterns of behavior, interests or activities. Symptoms are typically recognized between one and two years of age.[2] Long-term problems may include difficulties in performing daily tasks, creating and keeping relationships, and maintaining a job.[9]
The cause of autism spectrum is uncertain.[5] Risk factors include having an older parent, a family history of autism, and certain genetic conditions.[5] It is estimated that between 64% and 91% of risk is due to family history.[10] Diagnosis is based on symptoms.[5] The DSM-5 redefined the autism spectrum disorders to encompass the previous diagnoses of autism, Asperger syndrome, pervasive developmental disorder not otherwise specified (PDD-NOS), and childhood disintegrative disorder.[11]
Treatment efforts are generally individualized, and can include behavioural therapy, and the teaching of coping skills.[5] Medications may be used to try to help improve symptoms.[5] Evidence to support the use of medications, however, is not very strong.[7]
Autism spectrum is estimated to affect about 1% of people (62.2 million globally as of 2015[update]).[2][8] Males are diagnosed more often than females.[9] The term "spectrum" can refer to the range of symptoms or their severity, leading some to favor a distinction between severely disabled autistics who cannot speak or look after themselves, and higher functioning autistics.
In the United States, a revision to autism spectrum disorder (ASD) was presented in the Diagnostic and Statistical Manual of Mental Disorders version 5 (DSM-5), released May 2013.[12] The new diagnosis encompasses previous diagnoses of autistic disorder, Asperger syndrome, childhood disintegrative disorder, and PDD-NOS. Compared with the DSM-IV diagnosis of autistic disorder, the DSM-5 diagnosis of ASD no longer includes communication as a separate criterion, and has merged social interaction and communication into one category.[13] Slightly different diagnostic definitions are used in other countries. For example, the ICD-10 is the most commonly-used diagnostic manual in the UK and European Union.[14] Rather than categorizing these diagnoses, the DSM-5 has adopted a dimensional approach to diagnosing disorders that fall underneath the autism spectrum umbrella. Some have proposed that individuals on the autism spectrum may be better represented as a single diagnostic category. Within this category, the DSM-5 has proposed a framework of differentiating each individual by dimensions of severity, as well as associated features (i.e., known genetic disorders, and intellectual disability).
Another change to the DSM includes collapsing social and communication deficits into one domain. Thus, an individual with an ASD diagnosis will be described in terms of severity of social communication symptoms, severity of fixated or restricted behaviors or interests, hyper- or hyposensitivity to sensory stimuli, and associated features. The restricting of onset age has also been loosened from 3 years of age to "early developmental period", with a note that symptoms may manifest later when social demands exceed capabilities.[15]
Autism forms the core of the autism spectrum disorders. Asperger syndrome is closest to autism in signs and likely causes;[16] unlike autism, people with Asperger syndrome usually have no significant delay in language development, according to the older DSM-IV criteria.[17] PDD-NOS is diagnosed when the criteria are not met for a more specific disorder. Some sources also include Rett syndrome and childhood disintegrative disorder, which share several signs with autism but may have unrelated causes; other sources differentiate them from ASD, but group all of the above conditions into the pervasive developmental disorders.[16][18]
Autism, Asperger syndrome, and PDD-NOS are sometimes called the autistic disorders instead of ASD,[19] whereas autism itself is often called autistic disorder, childhood autism, or infantile autism.[20] Although the older term pervasive developmental disorder and the newer term autism spectrum disorder largely or entirely overlap,[18] the earlier was intended to describe a specific set of diagnostic labels, whereas the latter refers to a postulated spectrum disorder linking various conditions.[21] ASD is a subset of the broader autism phenotype (BAP), which describes individuals who may not have ASD but do have autistic-like traits, such as avoiding eye contact.[20]
Autism is characterized by persistent deficits in social communication and interaction across multiple contexts, as well as restricted, repetitive patterns of behavior, interests, or activities. These deficits are present in early childhood, and lead to clinically significant functional impairment.[22] There is also a unique form of autism called autistic savantism, where a child can display outstanding skills in music, art, and numbers with no practice.[23] Because of its relevance to different populations, self-injurious behaviors (SIB) are not considered a core characteristic of the ASD population however approximately 50% of those with ASD take part in some type of SIB (head-banging, self-biting) and are more at risk than other groups with developmental disabilities.[24]
Other characteristics of ASD include restricted and repetitive behaviors (RRBs) which include a large range of specific gestures and acts, it can even include certain behavioral traits as defined in the Diagnostic and Statistic Manual for Mental Disorders.[25]
Asperger syndrome was distinguished from autism in the DSM-IV by the lack of delay or deviance in early language development.[26] Additionally, individuals diagnosed with Asperger syndrome did not have significant cognitive delays.[27] PDD-NOS was considered "subthreshold autism" and "atypical autism" because it was often characterized by milder symptoms of autism or symptoms in only one domain (such as social difficulties).[28]
The DSM-5 eliminated the four separate diagnoses: Asperger Syndrome, Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS), Childhood Disintegrative Disorder, and Autistic Disorder and combined them under the diagnosis of Autism Spectrum Disorder.[22]
Autism spectrum disorders include a wide variety of characteristics. Some of these include behavioral characteristics which widely range from slow development of social and learning skills to difficulties creating connections with other people. They may develop these difficulties of creating connections due to anxiety or depression, which people with autism are more likely to experience, and as a result isolate themselves.[29] Other behavioral characteristics include abnormal responses to sensations including sights, sounds, touch, and smell, and problems keeping a consistent speech rhythm. The latter problem influences an individual's social skills, leading to potential problems in how they are understood by communication partners. Behavioral characteristics displayed by those with autism spectrum disorder typically influence development, language, and social competence. Behavioral characteristics of those with autism spectrum disorder can be observed as perceptual disturbances, disturbances of development rate, relating, speech and language, and motility.[30]
Autism spectrum disorders are thought to follow two possible developmental courses, although most parents report that symptom onset occurred within the first year of life.[31][32] One course of development is more gradual in nature, in which parents report concerns in development over the first two years of life and diagnosis is made around 3–4 years of age. Some of the early signs of ASDs in this course include decreased looking at faces, failure to turn when name is called, failure to show interests by showing or pointing, and delayed imaginative play.[33]
A second course of development is characterized by normal or near-normal development followed by loss of skills or regression in the first 2–3 years. Regression may occur in a variety of domains, including communication, social, cognitive, and self-help skills; however, the most common regression is loss of language.[34][35]
There continues to be a debate over the differential outcomes based on these two developmental courses. Some studies suggest that regression is associated with poorer outcomes and others report no differences between those with early gradual onset and those who experience a regression period.[36] While there is conflicting evidence surrounding language outcomes in ASD, some studies have shown that cognitive and language abilities at age 2 1⁄2 may help predict language proficiency and production after age 5.[37] Overall, the literature stresses the importance of early intervention in achieving positive longitudinal outcomes.[38]
Social skills present the most challenges for individuals with ASD. This leads to problems with friendships, romantic relationships, daily living, and vocational success.[39] Marriages are less common for those with ASD. Many of these challenges are linked to their atypical patterns of behavior and communication. It is common for children and adults with autism to struggle with social interactions because they are unable to relate to their peers.[40] All of these issues stem from cognitive impairments. Difficulty in this thought process is called "theory of the mind" or mind blindness which means that the mind has difficulty with thought process as well as being aware of what is going on around them.[41] Theory of mind is closely related to the pragmatic difficulties children with autism experience.[42]
Communication deficits are generally characterized by impairments regarding joint attention and social reciprocity, challenges with verbal language cues, and poor nonverbal communication skills [43] such as lack of eye contact and meaningful gestures and facial expressions.[44] Language behaviors typically seen in children with autism may include repetitive or rigid language, specific interests in conversation, and atypical language development.[44] ASD is a complex pragmatic language disorder which influences communication skills significantly.[45] Many children with ASD develop language skills at an uneven pace where they easily acquire some aspects of communication, while never fully developing other aspects.[44] In some cases, individuals remain completely nonverbal throughout their lives, although the accompanying levels of literacy and nonverbal communication skills vary.
They may not pick up on body language or social cues such as eye contact and facial expressions if they provide more information than the person can process at that time. Similarly, they have trouble recognizing subtle expressions of emotion and identifying what various emotions mean for the conversation. They struggle with understanding the context and subtext of conversational or printed situations, and have trouble forming resulting conclusions about the content. This also results in a lack of social awareness and atypical language expression.[46]
It is also common for individuals with ASD to communicate strong interest in a specific topic, speaking in lesson-like monologues about their passion instead of enabling reciprocal communication with whomever they are speaking to.[44] What looks like self-involvement or indifference toward others stems from a struggle to recognize or remember that other people have their own personalities, perspectives, and interests.[46] The ability to be focused in on one topic in communication is known as monotropism, and can be compared to "tunnel vision" in the mind for those individuals with ASD.[47] Language expression by those on the autism spectrum is often characterized by repetitive and rigid language. Often children with ASD repeat certain words, numbers, or phrases during an interaction, words unrelated to the topic of conversation. They can also exhibit a condition called echolalia in which they respond to a question by repeating the inquiry instead of answering.[44] However, this repetition can be a form of meaningful communication, a way that individuals with ASD try to express a lack of understanding or knowledge regarding the answer to the question.[48]
While specific causes of autism spectrum disorders have yet to be found, many risk factors identified in the research literature may contribute to their development. These risk factors include genetics, prenatal and perinatal factors, neuroanatomical abnormalities, and environmental factors. It is possible to identify general risk factors, but much more difficult to pinpoint specific factors. Given the current state of knowledge, prediction can only be of a global nature and therefore requires the use of general markers.[49]
As of 2018, understanding of genetic risk factors had shifted from a focus on a few alleles, to an understanding that genetic involvement in ASD is probably diffuse, depending on a large number of variants, some of which are common and have a small effect, and some of which are rare and have a large effect. The most common gene disrupted with large effect rare variants appeared to be CHD8, but less than 0.5% of people with ASD have such a mutation. Some ASD is associated with clearly genetic conditions, like fragile X syndrome; however only around 2% of people with ASD have fragile X.[50]
As of 2018, it appeared that somewhere between 74% and 93% of ASD risk is heritable and that after an older child is diagnosed with ASD, 7–20% of subsequent children are likely to be as well.[50] If parents have a child with ASD they have a 2% to 8% chance of having a second child with ASD. If the child with ASD is an identical twin the other will be affected 36 to 95 percent of the time. If they are fraternal twins the other will only be affected up to 31 percent of the time.[51]
Some of the alterations that contribute to the development of the autistic spectrum: SNVs (single-nucleotide variations), indels (insertions-deletions) and SVs (structural variants). These associations have been identified through whole-genome studies, such as WGS (whole-genome sequencing) and GWAS (genome-wide analysis association studies).
In early onset disorders, such as autism, de novo mutations have been identified as risk factors. One study has identified 64 SNVs and 5 indels de novo on average. By performing an analysis of these variants, comparing cases and controls, considering SNVs and indels in 179 genes associated with autism or close to them, studies observed that the relative risk of missense mutations or variants in promoter regions and UTR (untranslated region), increases versus controls.
The identification of SVs has been very useful too, since structural alterations in the chromosomes are able to rearrange the genome, altering its functionality, depending on the size and the region they affect.
After the analysis, 98,785 SVs were identified, with an average of 5,843 variants per individual: 171 SVs were de novo, more frequent in the germ line. Some of these variants affected genes associated with autism, such as the GRIN2B gene, balanced translocation, or the deletion of exons 8, 9, and 10 of the CHD2 gene.
No significant differences were observed regarding the size of certain rearrangements in cases and controls, though a slight increase in number was observed for cases relative to controls.
All these genetic variants contribute to the development of the autistic spectrum, however, it can not be guaranteed that they are determinants for the development.[52]
Several prenatal and perinatal complications have been reported as possible risk factors for autism. These risk factors include maternal gestational diabetes, maternal and paternal age over 30, bleeding after first trimester, use of prescription medication (e.g. valproate) during pregnancy, and meconium in the amniotic fluid. While research is not conclusive on the relation of these factors to autism, each of these factors has been identified more frequently in children with autism, compared to their siblings who do not have autism, and other typically developing youth.[53] While it is unclear if any single factors during the prenatal phase affect the risk of autism,[54] complications during pregnancy may be a risk.[54]
Low vitamin D levels in early development has been hypothesized as a risk factor for autism.[55]
In 1998 Andrew Wakefield led a fraudulent study that suggested that the MMR vaccine may cause autism.[56][57][58][59][60] This conjecture suggested that autism results from brain damage caused either by the MMR vaccine itself, or by thimerosal, a vaccine preservative.[61] No convincing scientific evidence supports these claims, and further evidence continues to refute them, including the observation that the rate of autism continues to climb despite elimination of thimerosal from routine childhood vaccines.[62] A 2014 meta-analysis examined ten major studies on autism and vaccines involving 1.25 million children worldwide; it concluded that neither the MMR vaccine, which has never contained thimerosal,[63] nor the vaccine components thimerosal or mercury, lead to the development of ASDs.[64]
In general, neuroanatomical studies support the concept that autism may involve a combination of brain enlargement in some areas and reduction in others.[65] These studies suggest that autism may be caused by abnormal neuronal growth and pruning during the early stages of prenatal and postnatal brain development, leaving some areas of the brain with too many neurons and other areas with too few neurons.[66] Some research has reported an overall brain enlargement in autism, while others suggest abnormalities in several areas of the brain, including the frontal lobe, the mirror neuron system, the limbic system, the temporal lobe, and the corpus callosum.[67][68]
In functional neuroimaging studies, when performing theory of mind and facial emotion response tasks, the median person on the autism spectrum exhibits less activation in the primary and secondary somatosensory cortices of the brain than the median member of a properly sampled control population. This finding coincides with reports demonstrating abnormal patterns of cortical thickness and grey matter volume in those regions of autistic persons' brains.[69]
The mirror neuron system (MNS) consists of a network of brain areas that have been associated with empathy processes in humans.[70] In humans, the MNS has been identified in the inferior frontal gyrus (IFG) and the inferior parietal lobule (IPL) and is thought to be activated during imitation or observation of behaviors.[71] The connection between mirror neuron dysfunction and autism is tentative, and it remains to be seen how mirror neurons may be related to many of the important characteristics of autism.[72][73]
A number of discrete brain regions and networks among regions that are involved in dealing with other people have been discussed together under the rubric of the "social brain". As of 2012[update], there was a consensus that autism spectrum is likely related to problems with interconnectivity among these regions and networks, rather than problems with any specific region or network.[74]
Functions of the temporal lobe are related to many of the deficits observed in individuals with ASDs, such as receptive language, social cognition, joint attention, action observation, and empathy. The temporal lobe also contains the superior temporal sulcus (STS) and the fusiform face area (FFA), which may mediate facial processing. It has been argued that dysfunction in the STS underlies the social deficits that characterize autism. Compared to typically developing individuals, one fMRI study found that individuals with high-functioning autism had reduced activity in the FFA when viewing pictures of faces.[75]
It has been suggested that ASD could be linked to mitochondrial disease (MD), a basic cellular abnormality with the potential to cause disturbances in a wide range of body systems.[76] A recent meta-analysis study, as well as other population studies have shown that approximately 5% of children with ASD meet the criteria for classical MD.[77] It is unclear why the MD occurs considering that only 23% of children with both ASD and MD present with mitochondrial DNA (mtDNA) abnormalities.[77]
It has been hypothesized that increased activity of serotonin in the developing brain may facilitate the onset of autism spectrum disorder, with an association found in six out of eight studies between the use of selective serotonin reuptake inhibitors (SSRIs) by the pregnant mother and the development of ASD by the child exposed to SSRI in the antenatal environment. The study could not definitively conclude SSRIs caused the increased risk for ASDs due to the biases found in those studies, and the authors called for more definitive, better conducted studies.[78]
ASD can be detected as early as 18 months or even younger in some cases.[79] A reliable diagnosis can usually be made by the age of two years.[80] The diverse expressions of ASD symptoms pose diagnostic challenges to clinicians. Individuals with an ASD may present at various times of development (e.g., toddler, child, or adolescent), and symptom expression may vary over the course of development.[81] Furthermore, clinicians must differentiate among pervasive developmental disorders, and may also consider similar conditions, including intellectual disability not associated with a pervasive developmental disorder, specific language disorders, ADHD, anxiety, and psychotic disorders.[82]
Considering the unique challenges in diagnosing ASD, specific practice parameters for its assessment have been published by the American Academy of Neurology,[83] the American Academy of Child and Adolescent Psychiatry,[81] and a consensus panel with representation from various professional societies.[84] The practice parameters outlined by these societies include an initial screening of children by general practitioners (i.e., "Level 1 screening") and for children who fail the initial screening, a comprehensive diagnostic assessment by experienced clinicians (i.e. "Level 2 evaluation"). Furthermore, it has been suggested that assessments of children with suspected ASD be evaluated within a developmental framework, include multiple informants (e.g., parents and teachers) from diverse contexts (e.g., home and school), and employ a multidisciplinary team of professionals (e.g., clinical psychologists, neuropsychologists, and psychiatrists).[85]
After a child shows initial evidence of ASD tendencies, psychologists administer various psychological assessment tools to assess for ASD.[85] Among these measurements, the Autism Diagnostic Interview-Revised (ADI-R) and the Autism Diagnostic Observation Schedule (ADOS) are considered the "gold standards" for assessing autistic children.[86][87] The ADI-R is a semi-structured parent interview that probes for symptoms of autism by evaluating a child's current behavior and developmental history. The ADOS is a semistructured interactive evaluation of ASD symptoms that is used to measure social and communication abilities by eliciting several opportunities (or "presses") for spontaneous behaviors (e.g., eye contact) in standardized context. Various other questionnaires (e.g., The Childhood Autism Rating Scale, Autism Treatment Evaluation Checklist) and tests of cognitive functioning (e.g., The Peabody Picture Vocabulary Test) are typically included in an ASD assessment battery.
In the UK, there is some diagnostic use of the Diagnostic Interview for Social and Communication Disorders (DISCO)[88] which was developed for use at The Centre for Social and Communication Disorders, by Lorna Wing and Judith Gould, as both a clinical and a research instrument for use with children and adults of any age. The DISCO is designed to elicit a picture of the whole person through the story of their development and behavior. In clinical work, the primary purpose is to facilitate understanding of the pattern over time of the specific skills and impairments that underlie the overt behavior. If no information is available, the clinician has to obtain as much information as possible concerning the details of current skills and pattern of behavior of the person. This type of dimensional approach to clinical description is useful for prescribing treatment.[89]
Autism spectrum disorders tend to be highly comorbid with other disorders. Comorbidity may increase with age and may worsen the course of youth with ASDs and make intervention/treatment more difficult. Distinguishing between ASDs and other diagnoses can be challenging, because the traits of ASDs often overlap with symptoms of other disorders, and the characteristics of ASDs make traditional diagnostic procedures difficult.[90][91]
The most common medical condition occurring in individuals with autism spectrum disorders is seizure disorder or epilepsy, which occurs in 11-39% of individuals with ASD.[92] Tuberous sclerosis, a medical condition in which non-malignant tumors grow in the brain and on other vital organs, occurs in 1-4% of individuals with ASDs.[93]
Intellectual disabilities are some of the most common comorbid disorders with ASDs. Recent estimates suggest that 40-69% of individuals with ASD have some degree of an intellectual disability,[36] more likely to be severe for females. A number of genetic syndromes causing intellectual disability may also be comorbid with ASD, including fragile X syndrome, Down syndrome, Prader-Willi and Angelman syndromes, and Williams syndrome.[94]
Learning disabilities are also highly comorbid in individuals with an ASD. Approximately 25-75% of individuals with an ASD also have some degree of a learning disability.[95]
Various anxiety disorders tend to co-occur with autism spectrum disorders, with overall comorbidity rates of 7-84%.[36] Rates of comorbid depression in individuals with an ASD range from 4-58%.[96] The relationship between ASD and schizophrenia remains a controversial subject under continued investigation, and recent meta-analyses have examined genetic, environmental, infectious, and immune risk factors that may be shared between the two conditions.[97][98][99]
Deficits in ASD are often linked to behavior problems, such as difficulties following directions, being cooperative, and doing things on other people's terms.[100] Symptoms similar to those of attention deficit hyperactivity disorder (ADHD) can be part of an ASD diagnosis.[101]
Sensory processing disorder is also comorbid with ASD, with comorbidity rates of 42-88%.[102]
There is no known cure for autism, although those with Asperger syndrome and those who have autism and require little-to-no support are more likely to experience a lessening of symptoms over time.[103][104][105] The main goals of treatment are to lessen associated deficits and family distress, and to increase quality of life and functional independence. In general, higher IQs are correlated with greater responsiveness to treatment and improved treatment outcomes.[106][107] Although evidence-based interventions for autistic children vary in their methods, many adopt a psychoeducational approach to enhancing cognitive, communication, and social skills while minimizing problem behaviors. It has been argued that no single treatment is best and treatment is typically tailored to the child's needs.[108]
Intensive, sustained special education programs and behavior therapy early in life can help children acquire self-care, social, and job skills. Available approaches include applied behavior analysis, developmental models, structured teaching, speech and language therapy, social skills therapy, and occupational therapy.[108] Among these approaches, interventions either treat autistic features comprehensively, or focus treatment on a specific area of deficit.[107] Generally, when educating those with autism, specific tactics may be used to effectively relay information to these individuals. Using as much social interaction as possible is key in targeting the inhibition autistic individuals experience concerning person-to-person contact. Additionally, research has shown that employing semantic groupings, which involves assigning words to typical conceptual categories, can be beneficial in fostering learning.[109]
There has been increasing attention to the development of evidence-based interventions for young children with ASD. Two theoretical frameworks outlined for early childhood intervention include applied behavioral analysis (ABA) and the developmental social-pragmatic model (DSP).[107] Although ABA therapy has a strong evidence base, particularly in regard to early intensive home-based therapy, ABA's effectiveness may be limited by diagnostic severity and IQ of the person affected by ASD.[110] The Journal of Clinical Child and Adolescent Psychology has deemed two early childhood interventions as "well-established": individual comprehensive ABA, and focused teacher-implemented ABA combined with DSP.[107]
Another evidence-based intervention that has demonstrated efficacy is a parent training model, which teaches parents how to implement various ABA and DSP techniques themselves.[107] Various DSP programs have been developed to explicitly deliver intervention systems through at-home parent implementation.
A multitude of unresearched alternative therapies have also been implemented. Many have resulted in harm to autistic people and should not be employed unless proven to be safe.[108]
In October 2015, the American Academy of Pediatrics (AAP) proposed new evidence-based recommendations for early interventions in ASD for children under 3.[111] These recommendations emphasize early involvement with both developmental and behavioral methods, support by and for parents and caregivers, and a focus on both the core and associated symptoms of ASD.[111]
The U.S. Center for Disease Control's most recent estimate is that 1 out of every 68 children, or 14.7 per 1,000, are affected by some form of ASD as of 2010[update].[112] Reviews tend to estimate a prevalence of 6 per 1,000 for autism spectrum disorders as a whole,[113] although prevalence rates vary for each of the developmental disorders in the spectrum. Autism prevalence has been estimated at 1-2 per 1,000, Asperger syndrome at roughly 0.6 per 1,000, childhood disintegrative disorder at 0.02 per 1,000, and PDD-NOS at 3.7 per 1,000.[113] These rates are consistent across cultures and ethnic groups, as autism is considered a universal disorder.[36]
While rates of autism spectrum disorders are consistent across cultures, they vary greatly by gender, with boys affected far more frequently than girls. The average male-to-female ratio for ASDs is 4.2:1,[114] affecting 1 in 70 boys, but only 1 in 315 girls.[115] Girls, however, are more likely to have associated cognitive impairment. Among those with an ASD and intellectual disability, the sex ratio may be closer to 2:1.[116] Prevalence differences may be a result of gender differences in expression of clinical symptoms, with women and girls with autism showing less atypical behaviors and, therefore, less likely to receive an ASD diagnosis.[117]
Controversies have surrounded various claims regarding the etiology of autism spectrum disorders. In the 1950s, the "refrigerator mother theory" emerged as an explanation for autism. The hypothesis was based on the idea that autistic behaviors stem from the emotional frigidity, lack of warmth, and cold, distant, rejecting demeanor of a child's mother.[118] Naturally, parents of children with an autism spectrum disorder suffered from blame, guilt, and self-doubt, especially as the theory was embraced by the medical establishment and went largely unchallenged into the mid-1960s. The "refrigerator mother" theory has since continued to be refuted in scientific literature, including a 2015 systematic review which showed no association between caregiver interaction and language outcomes in ASD.[119]
Another controversial claim suggests that watching extensive amounts of television may cause autism. This hypothesis was largely based on research suggesting that the increasing rates of autism in the 1970s and 1980s were linked to the growth of cable television at this time.[62]
Families who care for an autistic child face added stress from a number of different causes. Parents may struggle to understand the diagnosis and to find appropriate care options. Parents often take a negative view of the diagnosis, and may struggle emotionally. In the words of one parent whose two children were both diagnosed with autism, "In the moment of diagnosis, it feels like the death of your hopes and dreams."[120] More than half of parents over the age of 50 are still living with their child as about 85% of people with ASD have difficulties living independently.[121]
The autism rights movement is a social movement within the context of disability rights that emphasizes the concept of neurodiversity, viewing the autism spectrum as a result of natural variations in the human brain rather than a disorder to be cured.[122] The autism rights movement advocates for including greater acceptance of autistic behaviors; therapies that focus on coping skills rather than imitating the behaviors of those without autism;[123] and the recognition of the autistic community as a minority group.[123][124] Autism rights or neurodiversity advocates believe that the autism spectrum is genetic and should be accepted as a natural expression of the human genome. This perspective is distinct from two other likewise distinct views: the medical perspective, that autism is caused by a genetic defect and should be addressed by targeting the autism gene(s), and fringe theories that autism is caused by environmental factors such as vaccines.[122] A common criticism against autistic activists is that the majority of them are "high-functioning" or have Asperger syndrome and do not represent the views of "low-functioning" autistic people.[124]
The number of students identified and served as eligible for autism services in the United States has increased from 5,413 children in 1991-1992 to 370,011 children in the 2010-2011 academic school year.[125] The United States Department of Health and Human Services reported approximately 1 in 68 children at age 8 are diagnosed with autism spectrum disorder (ASD) although onset is typically between ages 2 and 4.[125]
The increasing number of students with ASD in the schools presents significant challenges to teachers, school psychologists, and other school professionals.[125] These challenges include developing a consistent practice that best support the social and cognitive development of the increasing number of students with ASD.[125] Although there is considerable research addressing assessment, identification, and support services for children with ASD, there is a need for further research focused on these topics within the school context.[125] Further research on appropriate support services for students with ASD will provide school psychologists and other education professionals with specific directions for advocacy and service delivery that aim to enhance school outcomes for students with ASD.[125]
Attempts to identify and use best intervention practices for students with autism also pose a challenge due to overdependence on popular or well-known interventions and curricula.[125] Some evidence suggests that although these interventions work for some students, there remains a lack of specificity for which type of student, under what environmental conditions (one-on-one, specialized instruction or general education) and for which targeted deficits they work best.[125] More research is needed to identify what assessment methods are most effective for identifying the level of educational needs for students with ASD.
A difficulty for academic performance in students with ASD, is the tendency to generalize learning.[47] Learning is different for each student, which is the same for students with ASD. To assist in learning, accommodations are commonly put into place for students with differing abilities. The existing schema of these students works in different ways and can be adjusted to best support the educational development for each student.[126]
About half of autistics are unemployed, and one third of those with graduate degrees may be unemployed.[127] Among those on the autism spectrum who find work, most are employed in sheltered settings working for wages below the national minimum.[128] While employers state hiring concerns about productivity and supervision, experienced employers of autistics give positive reports of above average memory and detail orientation as well as a high regard for rules and procedure in autistic employees.[127] A majority of the economic burden of autism is caused by lost productivity in the job market.[129] Some studies also find decreased earning among parents who care for autistic children.[130][131] Adding content related to autism in existing diversity training can clarify misconceptions, support employees, and help provide new opportunities for autistics.[citation needed]
We favour use of the term 'autism-spectrum condition' rather than 'autism-spectrum disorder' as it is less stigmatising, and it reflects that these individuals have not only disabilities which require a medical diagnosis, but also areas of cognitive strength
The entire diagnosis and explanation took no more than 45 minutes. 'In the moment of diagnosis, it feels like the death of your hopes and dreams,' Louise [Laidler] says. There's a quiet grief in her voice, even though two decades have passed. 'In a way, it's even harder than a death, because you can't mourn and go on,' she says. 'You have to figure out how to care for your new child.'
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| リンク元 | 「autistic spectrum disorder」 |
| 拡張検索 | 「autism spectrum disorders」 |
| 関連記事 | 「disorder」「spectrum」「spectrum disorder」 |
自閉症圏障害、自閉性障害、自閉症スペクトラム