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102-491: The center conducts research and provides clinical services and medical training related to children and families. Topics of investigation include autism spectrum disorders , Tourette syndrome , other pediatric mental health concerns, parenting, and neurobiology . The center was started in 1911 as the Yale Clinic of Child Development by Arnold Gesell . Dr. Gesell, who is considered the father of child development in

204-452: A neurodevelopmental disorder , but the autism rights movement (and some researchers) see autistic people as part of humanity's natural neurodiversity . From this point of view, autistic people may also be diagnosed with a disability of some sort, but that disability may be rooted in the systemic structures of a society rather than in the person; thus, proponents argue that autistic people should be accommodated rather than cured. On

306-606: A "level" system, which ranks how in need of support the patient is, level 1 being the mildest and level 3 the severest, while the ICD-11 system has two axes, intellectual impairment and language impairment, as these are seen as the most crucial factors. Autism is currently defined as a highly variable neurodevelopmental disorder that is generally thought to cover a broad and deep spectrum , manifesting very differently from one person to another. Some have high support needs, may be nonspeaking , and experience developmental delays; this

408-426: A 4.25-fold increase; the study did not quantify the effects of wider awareness of autism, increased funding, and expanding support options resulting in parents' greater motivation to seek services. Another 2009 California study found that the reported increases are unlikely to be explained by changes in how qualifying condition codes for autism were recorded. Several environmental factors have been proposed to support

510-438: A broader medical condition or syndrome , representing about 25% of ASD cases. The causes of syndromic autism are often known, and monogenic disorders account for approximately 5% of these cases. Non-syndromic autism, also known as classic or idiopathic autism, represents the majority of cases, and its cause is typically polygenic and unknown. Autism has a strong genetic basis, although the genetics of autism are complex and it

612-530: A diagnosis as autism. A study of all Danish children born in 1994–99 found that children born later were more likely to be diagnosed at a younger age, supporting the argument that apparent increases in autism prevalence were at least partly due to decreases in the age of diagnosis. A 2009 study of California data found that the reported incidence of autism rose 7- to 8-fold from the early 1990s to 2007, and that changes in diagnostic criteria, inclusion of milder cases, and earlier age of diagnosis probably explain only

714-656: A general practice research database in England and Wales grew steadily during 1988–2001 from 0.11 to 2.98 per 10,000 person-years, and concluded that much of this increase may be due to changes in diagnostic practice. As late as the mid-1970s there was little evidence of a genetic role in autism; evidence from genetic epidemiology studies now suggests that it is one of the most heritable of all psychiatric conditions. The first studies of twins estimated heritability to be more than 90%; in other words, that genetics explains more than 90% of autism cases. When only one identical twin

816-449: A genetic reason why males are diagnosed more often, such as the imprinted brain hypothesis and the extreme male brain theory . Epidemiology of autism The epidemiology of autism is the study of the incidence and distribution of autism spectrum disorders (ASD). A 2022 systematic review of global prevalence of autism spectrum disorders found a median prevalence of 1% in children in studies published from 2012 to 2021, with

918-648: A low demand for coordination that ameliorated many challenges associated with disruptive turns." Autistic interests, and thus conversational topics, seem to be largely driven by an intense interest in specific topics ( monotropism ). Historically, autistic children were said to be delayed in developing a theory of mind , and the empathizing–systemizing theory has argued that while autistic people have compassion ( affective empathy ) for others with similar presentation of symptoms, they have limited, though not necessarily absent, cognitive empathy . This may present as social naïvety, lower than average intuitive perception of

1020-575: A model of social patterns, and develop coping mechanisms, referred to as " masking ", which have recently been found to come with psychological costs and a higher increased risk of suicidality. ASD includes 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. Autistic people may experience these challenges with forming connections due to anxiety or depression, which they are more likely to experience, and as

1122-923: A neurotypical bias in autism research, which has come to be scrutinized for "dehumanization, objectification, and stigmatization". Recent research has proposed that autistics' lack of readability and a neurotypical lack of effort to interpret atypical signals may cause a negative interaction loop, increasingly driving both groups apart into two distinct groups with different social interaction styles. Differences in verbal communication begin to be noticeable in childhood, as many autistic children develop language skills at an uneven pace. Verbal communication may be delayed or never develop ( nonverbal autism ), while reading ability may be present before school age ( hyperlexia ). Reduced joint attention seem to distinguish autistic from non-autistic infants. Infants may show delayed onset of babbling , unusual gestures, diminished responsiveness, and vocal patterns that are not synchronized with

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1224-573: A person can depend on context, and may vary over time. While the DSM and ICD greatly influence each other, there are also differences. For example, Rett syndrome was included in ASD in the DSM-5, but in the ICD-11 it was excluded and placed in the chapter on Developmental Anomalies. The ICD and the DSM change over time, and there has been collaborative work toward a convergence of the two since 1980 (when DSM-III

1326-464: A person with autism). 1 in 23 children (or 4.36%) aged 7 to 14 years have an autism diagnosis. A 2009 study reported that the annual incidence rate of Israeli children with a diagnosis of ASD receiving disability benefits rose from zero in 1982–1984 to 190 per million in 2004. It was not known whether these figures reflected true increases or other factors such as changes in diagnostic measures. Studies of autism frequency have been particularly rare in

1428-505: A person's ASD diagnosis did not influence their interest level. Thus, there has been a recent shift to acknowledge that autistic people may simply respond and behave differently than people without ASD. So far, research has identified two unconventional features by which autistic people create shared understanding ( intersubjectivity ): "a generous assumption of common ground that, when understood, led to rapid rapport, and, when not understood, resulted in potentially disruptive utterances; and

1530-645: A person's ability to understand and connect with others, as well as their adaptability to everyday situations, with its severity and support needs varying widely across the underlying spectrum . For example, some are nonverbal , while others have proficient spoken language. A formal diagnosis of ASD according to either the DSM-5 or the ICD-11 criteria requires not merely the presence of ASD symptoms, but symptoms that cause significant impairment in multiple domains of functioning, in addition to being atypical or excessive for

1632-547: A pervasive feature of the individual's functioning observable in all settings, although they may vary according to social, educational, or other context. Individuals along the spectrum exhibit a full range of intellectual functioning and language abilities. ICD-11 was produced by professionals from 55 countries out of the 90 involved and is the most widely used reference worldwide. The American Psychiatric Association 's Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision ( DSM-5-TR ), released in 2022,

1734-719: A prevalence of 1–2 per 1,000 for autism and close to 27.6 per 1,000 for ASD ; PDD-NOS is the vast majority of ASD, Asperger syndrome is about 0.3 per 1,000 and the atypical forms childhood disintegrative disorder and Rett syndrome are much rarer. A 2006 study of nearly 57,000 British nine- and ten-year-olds reported a prevalence of 3.89 per 1,000 for autism and 11.61 per 1,000 for ASD; these higher figures could be associated with broadening diagnostic criteria. Studies based on more detailed information, such as direct observation rather than examination of medical records, identify higher prevalence; this suggests that published figures may underestimate ASD's true prevalence. A 2009 study of

1836-507: A prevalence rate of approximately 1 to 2 percent. A 2011 study reported a 2.6 percent prevalence of autism in South Korea . Although incidence rates measure autism prevalence directly, most epidemiological studies report other frequency measures, typically point or period prevalence, or sometimes cumulative incidence. Attention is focused mostly on whether prevalence is increasing with time. Epidemiology defines several measures of

1938-628: A result isolate themselves. Other behavioral characteristics include abnormal responses to sensations (such as sights, sounds, touch, taste and smell) and problems keeping a consistent speech rhythm. The latter problem influences social skills, leading to potential problems in understanding for interlocutors. Autistic people's behavioral characteristics typically influence development, language, and social competence. Their behavioral characteristics can be observed as perceptual disturbances, disturbances of development rate, relating, speech and language, and motility. The second core symptom of autism spectrum

2040-423: A set of closely related and overlapping diagnoses such as Asperger syndrome and the syndrome formerly known as Kanner syndrome . This created unclear boundaries between the terms, so for the DSM-5 and ICD-11, a spectrum approach was taken. The new system is also more restrictive, meaning fewer people qualify for diagnosis. The DSM-5 and ICD-11 use different categorization tools to define this spectrum. DSM-5 uses

2142-491: 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 autistic people have such a mutation. The gene CHD8 encodes the protein chromodomain helicase DNA binding protein 8, which is a chromatin regulator enzyme that is essential during fetal development. CHD8 is an adenosine triphosphate (ATP)–dependent enzyme. The protein contains an Snf2 helicase domain that

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2244-501: A small study in 1998 in the United Kingdom suggesting a causal link between autism and the trivalent MMR vaccine . After data included in the report was shown to be deliberately falsified, the paper was retracted, and Wakefield was struck off the medical register in the United Kingdom. It is problematic to compare autism rates over the last three decades, as the diagnostic criteria for autism have changed with each revision of

2346-399: A steady course without remission (different developmental timelines are described in more detail below). Autistic people may be severely impaired in some respects but average, or even superior, in others. Clinicians consider assessment for ASD when a patient shows: These features are typically assessed with the following, when appropriate: There are many signs associated with autism;

2448-448: A substantial fraction of autism cases may be traceable to genetic causes that are highly heritable but not inherited: that is, the mutation that causes the autism is not present in the parental genome. 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

2550-421: A tendency to be associated with sedation and weight gain . Melatonin supplementation has been shown to improve insomnia related to autism. Stimulant therapy may improve mental processing speed when there is comorbid ADHD. Before the DSM-5 (2013) and ICD-11 (2022) diagnostic manuals were adopted, ASD was found under the diagnostic category pervasive developmental disorder . The previous system relied on

2652-413: A third of genes are expressed in the brain and there are few clues on which are relevant to autism. A few studies have found an association between autism and frequent use of acetaminophen (e.g. Tylenol, Paracetamol) by the mother during pregnancy. Autism is also associated with several other prenatal factors, including advanced age in either parent, and diabetes, bleeding, or use of psychiatric drugs in

2754-537: A trend of increasing prevalence over time. This increasing prevalence has reinforced the myth perpetuated by anti-vaccine activists that autism is caused by vaccines . Boys are also significantly far more frequently diagnosed than girls . There is no cure for autism. Some advocates of autistic people argue that efforts to find a cure are misguided and even harmful. Early intervention services based on applied behavior analysis (ABA) aim to teach children self-care, social and communicative skills. Guidelines from

2856-405: A trend of increasing prevalence over time. However, the study's 1% figure may reflect an underestimate of prevalence in low- and middle-income countries . ASD averages a 4.3:1 male-to-female ratio in diagnosis, not accounting for ASD in gender diverse populations, which overlap disproportionately with ASD populations. The number of children known to have autism has increased dramatically since

2958-431: A younger age, and improved efficiency of case ascertainment, can produce an increase in the frequency of autism ranging up to 29-fold depending on the frequency measure, suggesting that methodological factors may explain the observed increases in autism over time. A small 2008 study found that a significant number (40%) of people diagnosed with pragmatic language impairment as children in previous decades would now be given

3060-491: Is a 10% increase from the 1 in 59 rate in 2014, 105% increase from the 1 in 110 rate in 2006 and 176% increase from the 1 in 150 rate in 2000. Diagnostic criteria of ASD has changed significantly since the 1980s; for example, U.S. special-education autism classification was introduced in 1994. ASD is a complex neurodevelopmental disorder , and although what causes it is still not entirely known, efforts have been made to outline causative mechanisms and how they give rise to

3162-726: Is a pattern of restricted and repetitive behaviors, activities, and interests. In order to be diagnosed with ASD under the DSM-5-TR, a person must have at least two of the following behaviors: Autistic people can display many forms of repetitive or restricted behavior, which the Repetitive Behavior Scale-Revised (RBS-R) categorizes as follows. Self-injurious behaviors are relatively common in autistic people, and can include head-banging, self-cutting, self-biting, and hair-pulling. Some of these can result in serious injury or death. Following are theories about

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3264-734: Is acquired during childhood. Autistic people display atypical nonverbal behaviors or show differences in nonverbal communication . They may make infrequent eye contact , even when called by name, or avoid it altogether. This may be due to the high amount of sensory input received when making eye contact. Autistic people often recognize fewer emotions and their meaning from others' facial expressions, and may not respond with facial expressions expected by their non-autistic peers. Temple Grandin , an autistic woman involved in autism activism, described her inability to understand neurotypicals ' social communication as leaving her feeling "like an anthropologist on Mars". Autistic people struggle to understand

3366-461: Is arguably the best, screens a large sample of an entire community to identify possible cases, and then evaluates each possible case in more detail with standard diagnostic procedures. This last method typically produces the most reliable, and the highest, prevalence estimates. Estimates of the prevalence of autism vary widely depending on diagnostic criteria, age of children screened, and geographical location. Most recent reviews tend to estimate

3468-442: Is autistic, the other often has learning or social disabilities. For adult siblings, the risk of having one or more features of the broader autism phenotype might be as high as 30%, much higher than the risk in controls. About 10–15% of autism cases have an identifiable Mendelian (single-gene) condition, chromosome abnormality , or other genetic syndrome, and ASD is associated with several genetic disorders . Since heritability

3570-661: Is bidirectional, research on communication difficulties has since also begun to study non-autistic behavior, with researcher Catherine Crompton writing in 2020 that non-autistic people "struggle to identify autistic mental states, identify autistic facial expressions, overestimate autistic egocentricity, and are less willing to socially interact with autistic people. Thus, although non-autistic people are generally characterised as socially skilled, these skills may not be functional, or effectively applied, when interacting with autistic people." Any previously observed communication deficits of autistic people may thus have been constructed through

3672-464: Is diagnosed, bearing in mind genetic elements it is inherent from conception, and the gap between initiation and diagnosis is influenced by many factors unrelated to chance. Research focuses mostly on whether point or period prevalence is increasing with time; cumulative incidence is sometimes used in studies of birth cohorts . The three basic approaches used to estimate prevalence differ in cost and in quality of results. The simplest and cheapest method

3774-590: Is heritable. After an older child is diagnosed with ASD, 7% to 20% of subsequent children are likely to be as well. If parents have one autistic child, they have a 2% to 8% chance of having a second child who is autistic. If the autistic child is an identical twin, the other will be affected 36% to 95% of the time. A fraternal twin is affected up to 31% of the time. The large number of autistic people with unaffected family members may result from spontaneous structural variation , such as deletions , duplications or inversions in genetic material during meiosis . Hence,

3876-568: Is less than 100% and symptoms vary markedly among identical twins with autism, environmental factors are most likely a significant cause as well. If some of the risk is due to gene-environment interaction the 90% heritability may be too high; However, in 2017, the largest study, including over three million participants, estimated the heritability at 83%. Genetic linkage analysis has been inconclusive; many association analyses have had inadequate power. Studies have examined more than 100 candidate genes; many genes must be examined because more than

3978-420: Is lowered activity in the fusiform face area of the brain, which is associated with impaired perception of people versus objects. It has been proposed to classify autism using genetics as well as behavior. Autism spectrum disorder (ASD) can be classified into two categories: "syndromic autism" and "non-syndromic autism". Syndromic autism refers to cases where ASD is one of the characteristics associated with

4080-522: Is more likely with other co-existing diagnoses. Others have relatively low support needs; they may have more typical speech-language and intellectual skills but atypical social/conversation skills, narrowly focused interests , and wordy, pedantic communication. They may still require significant support in some areas of their lives. The spectrum model should not be understood as a continuum running from mild to severe, but instead means that autism can present very differently in each person. How it presents in

4182-711: Is possible to identify general factors, but much more difficult to pinpoint specific ones. Given the current state of knowledge, prediction can only be of a global nature and so requires the use of general markers. Research into causes has been hampered by the inability to identify biologically meaningful subgroups within the autistic population and by the traditional boundaries between the disciplines of psychiatry , psychology , neurology and pediatrics . Newer technologies such as fMRI and diffusion tensor imaging can help identify biologically relevant phenotypes (observable traits) that can be viewed on brain scans , to help further neurogenetic studies of autism; one example

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4284-422: Is responsible for the hydrolysis of ATP to adenosine diphosphate (ADP). CHD8 encodes a DNA helicase that functions as a repressor of transcription, remodeling chromatin structure by altering the position of nucleosomes. CHD8 negatively regulates Wnt signaling . Wnt signaling is important in the vertebrate early development and morphogenesis. It is believed that CHD8 also recruits the linker histone H1 and causes

4386-642: Is still being learnt about autism, the most recent DSM ( DSM-5 ) only has one diagnosis, autism spectrum disorder (ASD), which encompasses each of the previous four disorders. According to the new diagnostic criteria for ASD, one must have both struggles in social communication and interaction and restricted repetitive behaviors, interests and activities (RRBs). ASD diagnoses continue to be over four times more common among boys (1 in 34) than among girls (1 in 154), and they are reported in all racial, ethnic and socioeconomic groups. Studies have been conducted in several continents (Asia, Europe and North America) that report

4488-726: Is the current version of the DSM. It is the predominant mental health diagnostic system used in the United States and Canada, and is often used in Anglophone countries. Its fifth edition, DSM-5 , released in May 2013, was the first to define ASD as a single diagnosis, which is still the case in the DSM-5-TR. ASD encompasses previous diagnoses, including the four traditional diagnoses of autism— classic autism , Asperger syndrome , childhood disintegrative disorder , and pervasive developmental disorder not otherwise specified (PDD-NOS)—and

4590-528: Is to count known autism cases from sources such as schools and clinics, and divide by the population. This approach is likely to underestimate prevalence because it does not count children who have not been diagnosed yet, and it is likely to generate skewed statistics because some children have better access to treatment. The second method improves on the first by having investigators examine student or patient records looking for probable cases, to catch cases that have not been identified yet. The third method, which

4692-399: Is unclear whether ASD is explained more by rare mutations with major effects, or by rare multi-gene interactions of common genetic variants. Complexity arises due to interactions among multiple genes, the environment, and epigenetic factors which do not change DNA sequencing but are heritable and influence gene expression . Many genes have been associated with autism through sequencing

4794-794: The Centres for Disease Control (CDC), NICE and European Society for Child & Adolescent Psychiatry (ESCAP) endorse the use of ABA as it reduces symptoms that impair daily functioning and quality of life , although NICE acknowledges that ABA does not meet the highest level of evidence-quality. Additionally, some in the autism rights movement oppose its application due to a perception that it emphasises normalisation. Speech and occupational therapy , as well as augmentative and alternative modes of communication , are effective adjunctive therapies . At present, no medication has been shown to reduce "core symptoms" of ASD. However, some atypical antipsychotics can alleviate comorbid irritability, though with

4896-501: The Diagnostic and Statistical Manual (DSM), which outlines which symptoms meet the criteria for an ASD diagnosis. In 1983, the DSM did not recognize PDD-NOS or Asperger's syndrome , and the criteria for autistic disorder (AD) were more restrictive. The previous edition of the DSM, DSM-IV, included autistic disorder, childhood disintegrative disorder , PDD-NOS, and Asperger's syndrome. Due to inconsistencies in diagnosis and how much

4998-657: The Middle East . One rough estimate is that the prevalence of autism in Saudi Arabia is 18 per 10,000, slightly higher than the 13 per 10,000 reported in developed countries. (compared to 168 per 10,000 in the USA) In 1992, thiomersal -containing vaccines were removed in Denmark. A study at Aarhus University indicated that during the chemical's usage period (up through 1990), there was no trend toward an increase in

5100-588: The National Health Service determined that the prevalence of ASD in adults was approximately 1% of the population, with a higher prevalence in males and no significant variation between age groups; these results suggest that prevalence of ASD among adults is similar to that in children and rates of autism are not increasing. Attention has been focused on whether the prevalence of autism is increasing with time. Earlier prevalence estimates were lower, centering at about 0.5 per 1,000 for autism during

5202-493: The Review Journal of Autism and Developmental Disorders published a systematic review of 21 studies investigating associations between ASD, problematic internet use, and gaming disorder where the majority of the studies found positive associations between the disorders. Exactly what causes autism remains unknown. It was long mostly presumed that there is a common cause at the genetic, cognitive, and neural levels for

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5304-561: The United Kingdom . The reported autism incidence in the UK rose starting before the first introduction of the MMR vaccine in 1989. However, a perceived link between the two arising from the results of a fraudulent scientific study has caused considerable controversy, despite being subsequently disproved. A 2004 study found that the reported incidence of pervasive developmental disorders in

5406-529: The genetics of ASD are complex and it is unclear which genes are responsible. ASD is also associated with several intellectual or emotional gifts, which has led to a variety of hypotheses from within evolutionary psychiatry that autistic traits have played a beneficial role over human evolutionary history. Other proposed causes of autism have been controversial . The vaccine hypothesis has been extensively investigated and shown to be false, lacking any scientific evidence . Andrew Wakefield published

5508-465: The 1960s and 1970s and about 1 per 1,000 in the 1980s, as opposed to today's 23 per 1000. The number of reported cases of autism increased dramatically in the 1990s and 2000s, prompting ongoing investigations into several potential reasons: The reported increase is largely attributable to changes in diagnostic practices, referral patterns, availability of services, age at diagnosis, and public awareness. A widely cited 2002 pilot study concluded that

5610-562: The 1980s, at least partly due to changes in diagnostic practice; it is unclear whether prevalence has actually increased; and as-yet-unidentified environmental risk factors cannot be ruled out. In 2020, the Centers for Disease Control 's Autism and Developmental Disabilities Monitoring (ADDM) Network reported that approximately 1 in 54 children in the United States (1 in 34 boys, and 1 in 144 girls) are diagnosed with an autism spectrum disorder (ASD), based on data collected in 2016. This estimate

5712-475: The 200–2004 school year found a prevalence rate of 0.68% (or 1 per 147). A 2001 review of the medical research conducted by the Public Health Agency of Canada concluded that there was no link between MMR vaccine and either inflammatory bowel disease or autism. The review noted, "An increase in cases of autism was noted by year of birth from 1979 to 1992; however, no incremental increase in cases

5814-452: The DSM-5, the DSM separated social deficits and communication deficits into two domains. Further, the DSM-5 changed to an onset age in the early developmental period, with a note that symptoms may manifest later when social demands exceed capabilities, rather than the previous, more restricted three years of age. These changes remain in the DSM-5-TR. For many autistic people, characteristics first appear during infancy or childhood and follow

5916-565: The U.S. in the 1990s and have continued in the 2000s. For the 2006 surveillance year, identified ASD cases were an estimated 9.0 per 1000 children aged 8 years (95% confidence interval [CI] = 8.6–9.3). These numbers measure what is sometimes called "administrative prevalence", that is, the number of known cases per unit of population, as opposed to the true number of cases. This prevalence estimate rose 57% (95% CI 27%–95%) from 2002 to 2006. The National Health Interview Survey (NHIS) for 2014–2016 studied 30,502 US children and adolescents and found

6018-664: The United States, led the center until 1948. Subsequent directors were: This article about a university or college in Connecticut is a stub . You can help Misplaced Pages by expanding it . This autism -related article is a stub . You can help Misplaced Pages by expanding it . Autism spectrum Autism , or autism spectrum disorder ( ASD ), is a neurodevelopmental disorder characterized by repetitive, restricted, and inflexible patterns of behavior, interests, and activities, as well as difficulties in social interaction and social communication. Autism generally affects

6120-478: The United States. A further study in 2006 concluded that the apparent rise in administrative prevalence was the result of diagnostic substitution, mostly for findings of intellectual disability and learning disabilities. "Many of the children now being counted in the autism category would probably have been counted in the mental retardation or learning disabilities categories if they were being labeled 10 years ago instead of today," said researcher Paul Shattuck of

6222-603: The Waisman Center at the University of Wisconsin–Madison , in a statement. A population-based study in Olmsted County , Minnesota county found that the cumulative incidence of autism grew eightfold from the 1980–83 period to the 1995–97 period. The increase occurred after the introduction of broader, more-precise diagnostic criteria, increased service availability, and increased awareness of autism. During

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6324-516: The caregiver. In the second and third years, autistic children may have less frequent and less diverse babbling, consonants, words, and word combinations; their gestures are less often integrated with words. Autistic children are less likely to make requests or share experiences and more likely to simply repeat others' words ( echolalia ). The CDC estimated in 2015 that around 40% of autistic children do not speak at all. Autistic adults' verbal communication skills largely depend on when and how well speech

6426-417: The cause of self-injurious behavior in children with developmental delay, including autistic children: The suicide rate for verbal autistics is nine times that of the general population. Studies have supported the common belief that autistic people become exhausted or burnt out in some situations. Autistic people may have symptoms that do not contribute to the official diagnosis, but that can affect

6528-507: The children in Cambridgeshire , England used different methods to measure prevalence, and estimated that 40% of ASD cases go undiagnosed, with the two least-biased estimates of true prevalence being 11.3 and 15.7 per 1,000. A 2009 U.S. study based on 2006 data estimated the prevalence of ASD in eight-year-old children to be 9.0 per 1,000 (approximate range 8.6–9.3). A 2009 report based on the 2007 Adult Psychiatric Morbidity Survey by

6630-462: The contrary, other scientists argue that ASD impairs functioning in many ways that are inherent to the disorder itself and unrelated to society. The neurodiversity perspective has led to significant controversy among those who are autistic and advocates, practitioners, and charities. The precises causes of autism are unknown in most individual cases. Research shows that the disorder is highly heritable and polygenic, and neurobiological risks from

6732-513: The current disorder-focused spectrum model deconstruct autism into at least two separate phenomena: (1) a non-pathological spectrum of behavioral traits in the population, and (2) the neuropathological burden of rare genetic mutations and environmental risk factors potentially leading to neurodevelopmental and psychological disorders, (3) governed by an individual's cognitive ability to compensate. The World Health Organization 's International Classification of Diseases (11th Revision), ICD-11 ,

6834-721: The current number of diagnoses. More assessments for ASD occurred among 4-year-olds than the current 8-year-olds when they were 4 years of age prior to the pandemic. After the pandemic, the rate of current assessments has dropped, leading to possible delayed identification of ASD. The prevalence of autism in Africa is unknown. The prevalence of autism in the Americas overall is unknown. The Canadian government reported in 2019 that 1 in 50 children were diagnosed with autism spectrum disorder. However, preliminary results of an epidemiological study conducted at Montreal Children's Hospital in

6936-400: The development of the autism spectrum, but it cannot be guaranteed that they are determinants for the development. ASD may be under-diagnosed in women and girls due to an assumption that it is primarily a male condition, but genetic phenomena such as imprinting and X linkage have the ability to raise the frequency and severity of conditions in males, and theories have been put forward for

7038-404: The disorder. The risk of developing autism is increased in the presence of various prenatal factors, including advanced paternal age and diabetes in the mother during pregnancy . In rare cases, autism is strongly associated with agents that cause birth defects . It has been shown to be related to genetic disorders and with epilepsy . ASD is believed to be largely inherited , although

7140-449: The environment are also relevant. Autism frequently co-occurs with attention deficit hyperactivity disorder (ADHD), epilepsy and intellectual disability , and research indicates that autistic people have significantly higher rates of LGBTQ+ identities and feelings than the general population. Disagreements persist about what should be included as part of the diagnosis, whether there are meaningful subtypes or stages of autism, and

7242-693: The exposure starts at a younger age. In April 2021, Research in Autism Spectrum Disorders published a systematic review of 12 studies of video game addiction in ASD subjects that found that children, adolescents, and adults with ASD are at greater risk of video game addiction than those without ASD, and that the data from the studies suggested that internal and external factors (sex, attention and oppositional behavior problems, social aspects, access and time spent playing video games, parental rules, and game genre) were significant predictors of video game addiction in ASD subjects. In March 2022,

7344-414: The frequency of occurrence of a disease or condition: When studying how conditions are caused, incidence rates are the most appropriate measure of condition frequency as they assess probability directly. However, incidence can be difficult to measure with rarer conditions such as autism. In autism epidemiology, point or period prevalence is more useful than incidence, as the condition starts long before it

7446-562: The genomes of affected people and their parents. But most of the mutations that increase autism risk have not been identified. Typically, autism cannot be traced to a Mendelian (single-gene) mutation or to a single chromosome abnormality , and none of the genetic syndromes associated with ASD have been shown to selectively cause ASD. Numerous genes have been found, with only small effects attributable to any particular gene. Most loci individually explain less than 1% of cases of autism. As of 2018 , it appeared that between 74% and 93% of ASD risk

7548-647: The global pervasive developmental disorder (PDD). The INSERM found a prevalence of 27 per 10,000 for the ASD and a prevalence of 9 per 10,000 for the early infantile autism in 2003. Those figures are considered as underrated as the WHO gives figures between 30 and 60 per 10,000. The French Minister of Health gives a prevalence of 4.9 per 10,000 on its website but it counts only early infantile autism . A 2008 study in Germany found that inpatient admission rates for children with ASD increased 30% from 2000 to 2005, with

7650-640: The hypothesis that the actual frequency of autism has increased. These include certain foods, infectious disease, pesticides . There is overwhelming scientific evidence against the MMR hypothesis and no convincing evidence for the thiomersal (or Thimerosal) hypothesis, so these types of risk factors have to be ruled out. Although it is unknown whether autism's frequency has increased, any such increase would suggest directing more attention and funding toward addressing environmental factors instead of continuing to focus on genetics. The COVID-19 pandemic may have impacted

7752-470: The incidence of autism. Between 1991 and 2000 the incidence increased, including among children born after the discontinuation of thimerosal. France made autism the national focus for the year 2012 and the Health Ministry estimated the rate of autism in 2012 to have been 0.67%, i.e. 1 in 150. Eric Fombonne made some studies in the years 1992 and 1997. He found a prevalence of 16 per 10,000 for

7854-458: The individual's age and sociocultural context. Common signs of ASD include difficulty with social interaction and verbal and nonverbal communication , along with perseverative interests , stereotypic body movements , rigid routines, and hyper- or hypo-reactivity to sensory input . The World Health Organization (WHO), UK National Institute for Health and Care Excellence (NICE), and American Psychological Association classify autism as

7956-410: The individual's age and sociocultural context. The onset of the disorder occurs during the developmental period, typically in early childhood, but symptoms may not become fully manifest until later, when social demands exceed limited capacities. Deficits are sufficiently severe to cause impairment in personal, family, social, educational, occupational or other important areas of functioning and are usually

8058-815: The interpersonal relationship difficulties between autistic people and their non-autistic counterparts and how to solve them through teaching neurotypical social skills, but newer research has also evaluated what autistic people want from friendships, such as a sense of belonging and good mental health. Children with ASD are more frequently involved in bullying situations than their non-autistic peers, and predominantly experience bullying as victims rather than perpetrators or victim-perpetrators, especially after controlling for comorbid psychopathology. Prioritizing dependability and intimacy in friendships during adolescence, coupled with lowered friendship quantity and quality, often lead to increased loneliness in autistic people. As they progress through life, autistic people observe and form

8160-600: The largest rise between 2000 and 2001 and a decline between 2001 and 2003. Inpatient rates for all mental disorders also rose for ages up to 15 years, so that the ratio of ASD to all admissions rose from 1.3% to 1.4%. A 2009 study in Norway reported prevalence rates for ASD ranging from 0.21% to 0.87%, depending on assessment method and assumptions about non-response, suggesting that methodological factors explain large variances in prevalence rates in different studies. The incidence and changes in incidence with time are unclear in

8262-660: The mother during pregnancy. Autism was found to be indirectly linked to prepregnancy obesity and low weight mothers. It is not known whether mutations that arise spontaneously in autism and other neuropsychiatric disorders come mainly from the mother or the father, or whether the mutations are associated with parental age. However, recent studies have identified advancing paternal age as a significant indicator for ASD. Increased chance of autism has also been linked to rapid "catch-up" growth for children born to mothers who had unhealthy weight at conception. A large 2008 population study of Swedish parents of children with autism found that

8364-536: The observed increase in autism in California cannot be explained by changes in diagnostic criteria, but a 2006 analysis found that special education data poorly measured prevalence because so many cases were undiagnosed, and that the 1994–2003 U.S. increase was associated with declines in other diagnostic categories, indicating that diagnostic substitution had occurred. A 2007 study that modeled autism incidence found that broadened diagnostic criteria, diagnosis at

8466-443: The other hand, genes controlling expression of glial and immune cells in the brain, e.g. astrocytes and microglia , respectively, are over-expressed, which correlates with increased number of glial and immune cells found in postmortem ASD brains. Some genes under investigation in ASD pathophysiology are those that affect the mTOR signaling pathway, which supports cell growth and survival. All these genetic variants contribute to

8568-469: The parents were more likely to have been hospitalized for a mental disorder, that schizophrenia was more common among the mothers and fathers, and that depression and personality disorders were more common among the mothers. It is not known how many siblings of autistic individuals are themselves autistic. Several studies based on clinical samples have given quite different estimates, and these clinical samples differ in important ways from samples taken from

8670-577: The person or the family. In September 2018, the Review Journal of Autism and Developmental Disorders published a systematic review of 47 studies published from 2005 to 2016 that concluded that associations between autism spectrum disorder (ASD) and screen time was inconclusive. In May 2019, the Journal of Developmental and Behavioral Pediatrics published a systematic review of 16 studies that found that children and adolescents with ASD are exposed to more screen time than typically developing peers and that

8772-438: The presence of other disorders or factors that likely contribute to the symptoms, other neurodevelopmental or mental disorders, intellectual disability, or language impairment). The symptom domains are (a) social communication and (b) restricted, repetitive behaviors, and there is the option of specifying a separate severity—the negative effect of the symptoms on the person—for each domain, rather than just overall severity. Before

8874-1396: The presentation varies widely: The broader autism phenotype describes people who may not have ASD but do have autistic traits , such as abnormalities in eye contact and stimming . According to the medical model, autistic people experience social communications impairments . Until 2013, deficits in social function and communication were considered two separate symptom domains. The current social communication domain criteria for autism diagnosis require people to have deficits across three social skills: social-emotional reciprocity, nonverbal communication, and developing and sustaining relationships. A deficit-based view predicts that autistic–autistic interaction would be less effective than autistic–non-autistic interactions or even non-functional. But recent research has found that autistic–autistic interactions are as effective in information transfer as interactions between non-autistics are, and that communication breaks down only between autistics and non-autistics. Also contrary to social cognitive deficit interpretations, recent (2019) research recorded similar social cognitive performances in autistic and non-autistic adults, with both of them rating autistic individuals less favorably than non-autistic individuals; however, autistic individuals showed more interest in engaging with autistic people than non-autistic people did, and learning of

8976-419: The range of diagnoses that included the word "autism". Rather than distinguishing among these diagnoses, the DSM-5 and DSM-5-TR adopt a dimensional approach with one diagnostic category for disorders that fall under the autism spectrum umbrella. Within that category, the DSM-5 and the DSM include a framework that differentiates each person by dimensions of symptom severity, as well as by associated features (i.e.,

9078-917: The regulation of long non-coding RNAs (lncRNAs), and the regulation of X chromosome inactivation (XCI) initiation, via regulation of Xist long non-coding RNA, the master regulator of XCI, though competitive binding to Xist regulatory regions. Some ASD is associated with clearly genetic conditions, like fragile X syndrome , but only around 2% of autistic people have fragile X. Hypotheses from evolutionary psychiatry suggest that these genes persist because they are linked to human inventiveness, intelligence or systemising. Current research suggests that genes that increase susceptibility to ASD are ones that control protein synthesis in neuronal cells in response to cell needs, activity and adhesion of neuronal cells, synapse formation and remodeling, and excitatory to inhibitory neurotransmitter balance. Therefore, although up to 1,000 different genes are thought to increase

9180-772: The repression of β-catenin and p53 target genes. The importance of CHD8 can be observed in studies where CHD8-knockout mice died after 5.5 embryonic days because of widespread p53-induced apoptosis. Some studies have determined the role of CHD8 in autism spectrum disorder (ASD). CHD8 expression significantly increases during human mid-fetal development. The chromatin remodeling activity and its interaction with transcriptional regulators have shown to play an important role in ASD aetiology . The developing mammalian brain has conserved CHD8 target regions that are associated with ASD risk genes. The knockdown of CHD8 in human neural stem cells results in dysregulation of ASD risk genes that are targeted by CHD8. Recently CHD8 has been associated with

9282-452: The risk of ASD, all of them eventually affect normal neural development and connectivity between different functional areas of the brain in a similar manner that is characteristic of an ASD brain. Some of these genes are known to modulate production of the GABA neurotransmitter, the nervous system's main inhibitory neurotransmitter. These GABA-related genes are under-expressed in an ASD brain. On

9384-546: The same period, the reported number of autism cases grew 22-fold in the same location, suggesting that counts reported by clinics or schools provide misleading estimates of the true incidence of autism. A 2008 study in Venezuela reported a prevalence of 1.1 per 1,000 for autism and 1.7 per 1,000 for ASD. A journal reports that the median prevalence of ASD among 2–6-year-old children who are reported in China from 2000 upwards

9486-409: The significance of autism-associated traits in the wider population. The combination of broader criteria, increased awareness, and the potential increase of actual prevalence, has led to considerably increased estimates of autism prevalence since the 1990s. The WHO estimates about 1 in 100 children had autism between 2012 and 2021, as that was the average estimate in studies during that period, with

9588-546: The social and non-social components of ASD's symptoms, described as a triad in the classic autism criteria. But it is increasingly suspected that autism is instead a complex disorder whose core aspects have distinct causes that often cooccur. It is unlikely that ASD has a single cause; many risk factors identified in the research literature may contribute to ASD. These include genetics, prenatal and perinatal factors (meaning factors during pregnancy or very early infancy), neuroanatomical abnormalities, and environmental factors. It

9690-523: The social context and subtext of neurotypical conversational or printed situations, and form different conclusions about the content. Autistic people may not control the volume of their voice in different social settings. At least half of autistic children have atypical prosody . What may look like self-involvement or indifference to non-autistic people stems from autistic differences in recognizing how other people have their own personalities, perspectives, and interests. Most published research focuses on

9792-482: The utility or meaning of body language , social reciprocity, or social expectations, including the habitus , social cues , and some aspects of sarcasm, which to some degree may also be due to comorbid alexithymia . But recent research has increasingly questioned these findings, as the " double empathy problem " theory (2012) argues that there is a lack of mutual understanding and empathy between both non-autistic persons and autistic individuals. As communication

9894-449: The vaccination rate of the triple MMR vaccine dropped to near zero and was replaced with MR and M vaccine, the incidence rate grew to 97 and 161 cases per 10,000 children born in 1993 and 1994, respectively, indicating that the combined MMR vaccine did not cause autism. A 2004 Japanese autism association reported that about 360.000 people have typical Kanner-type autism . Across all ages, 1 in 70 Australians identify as being autistic (or

9996-586: The weighted prevalence of ASD was 2.47% (24.7 per 1,000); 3.63% in boys and 1.25% in girls. Across the 3-year reporting period, the prevalence was 2.24% in 2014, 2.41% in 2015, and 2.76% in 2016. The number of new cases of autism spectrum disorder (ASD) in Caucasian boys is roughly 50% higher than found in Hispanic children, and approximately 30% more likely to occur than in Non-Hispanic white children in

10098-490: Was 10.3/10,000. A 2008 Hong Kong study reported an ASD incidence rate similar to those reported in Australia and North America, and lower than Europeans. It also reported a prevalence of 1.68 per 1,000 for children under 15 years. A 2005 study of a part of Yokohama with a stable population of about 300,000 reported a cumulative incidence to age 7 years of 48 cases of ASD per 10,000 children in 1989, and 86 in 1990. After

10200-436: Was observed after the introduction of MMR vaccination." After the introduction of MMR, "A time trend analysis found no correlation between prevalence of MMR vaccination and the incidence of autism in each birth cohort from 1988 to 1993." According to a report by the Centers for Disease Control and Prevention in 2020, 1 in 36 children have ASD (27.6 in every 1,000). The number of diagnosed cases of autism grew dramatically in

10302-574: Was published and ICD-9 was current), including more rigorous biological assessment—in place of historical experience—and a simplification of the classification system. As of 2023, empirical and theoretical research is leading to a growing consensus among researchers that the established ASD criteria are ineffective descriptors of autism as a whole, and that alternative research approaches must be encouraged, such as going back to autism prototypes, exploring new causal models of autism, or developing transdiagnostic endophenotypes . Proposed alternatives to

10404-466: Was released in June 2018 and came into full effect as of January 2022. It describes ASD as follows: Autism spectrum disorder is characterised by persistent deficits in the ability to initiate and to sustain reciprocal social interaction and social communication, and by a range of restricted, repetitive, and inflexible patterns of behaviour, interests or activities that are clearly atypical or excessive for

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