Tag Archives: Hypotheses

Question?: Rett Syndrome Genetics

George asks…

what is autism?

Im not sure what that is

admin answers:

Autism is a brain development disorder that impairs social interaction and communication, and causes restricted and repetitive behavior, all starting before a child is three years old. This set of signs distinguishes autism from milder autism spectrum disorders (ASD) such as Asperger syndrome.[2]

Autism has a strong genetic basis, although the genetics of autism are complex and it is unclear whether ASD is explained more by multigene interactions or by rare mutations.[3] In rare cases, autism is strongly associated with agents that cause birth defects.[4] Other proposed causes, such as childhood vaccines, are controversial and the vaccine hypotheses lack convincing scientific evidence.[5] Most recent reviews estimate a prevalence of one to two cases per 1,000 people for autism, and about six per 1,000 for ASD, with ASD averaging a 4.3:1 male-to-female ratio. The number of people known to have autism has increased dramatically since the 1980s, at least partly due to changes in diagnostic practice; the question of whether actual prevalence has increased is unresolved.[6]

Autism affects many parts of the brain; how this occurs is poorly understood. Parents usually notice signs in the first two years of their child’s life. Early behavioral or cognitive intervention can help children gain self-care, social, and communication skills. There is no cure.[7] Few children with autism live independently after reaching adulthood, but some become successful,[8] and an autistic culture has developed, with some seeking a cure and others believing that autism is a condition rather than a disorder.[9]
Contents
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* 1 Classification
* 2 Characteristics
o 2.1 Social development
o 2.2 Communication
o 2.3 Repetitive behavior
o 2.4 Other symptoms
* 3 Causes
* 4 Mechanism
o 4.1 Pathophysiology
o 4.2 Neuropsychology
* 5 Screening
* 6 Diagnosis
* 7 Management
* 8 Prognosis
* 9 Epidemiology
* 10 History
* 11 References
* 12 External links

Classification

Autism is a brain development disorder that first gives signs during infancy or childhood and follows a steady course without remission or relapse.[2] Impairments result from maturation-related changes in various systems of the brain.[10] Autism is one of the five pervasive developmental disorders (PDD), which are characterized by widespread abnormalities of social interactions and communication, and severely restricted interests and highly repetitive behavior.[2]
Hans Asperger introduced the modern sense of the word autism in 1938.
Hans Asperger introduced the modern sense of the word autism in 1938.[11]

Of the other four PDD forms, Asperger syndrome is closest to autism in signs and likely causes; Rett syndrome and childhood disintegrative disorder share several signs with autism, but may have unrelated causes; PDD not otherwise specified (PDD-NOS) is diagnosed when the criteria are not met for a more specific disorder.[12] Unlike autism, Asperger’s has no substantial delay in language development.[13] The terminology of autism can be bewildering, with autism, Asperger’s and PDD-NOS often called the autism spectrum disorders (ASD)[7] or sometimes the autistic disorders,[14] whereas autism itself is often called autistic disorder, childhood autism, or infantile autism. In this article, autism refers to the classic autistic disorder, while other sources sometimes use autism or the autisms to refer to ASD,[15] or equate ASD with PDD.[16] ASD, in turn, 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.[17]

The manifestations of autism cover a wide spectrum, ranging from individuals with severe impairments—who may be silent, mentally disabled, and locked into hand flapping and rocking—to less impaired individuals who may have active but distinctly odd social approaches, narrowly focused interests, and verbose, pedantic communication.[18] Sometimes the syndrome is divided into low-, medium- and high-functioning autism (LFA, MFA, and HFA), based on IQ thresholds,[19] or on how much support the individual requires in daily life; these subdivisions are not standardized and are controversial. Autism can also be divided into syndromal and non-syndromal autism, where the former is associated with severe or profound mental retardation or a congenital syndrome with physical symptoms, such as tuberous sclerosis.[20] Although individuals with Asperger’s tend to perform better cognitively than those with autism, the extent of the overlap between Asperger’s, HFA, and non-syndromal autism is unclear.[21]

Some studies have reported diagnoses of autism in children due to a loss of language or social skills after 14 months of age, as opposed to a failure to make progress. Several terms are used for this phenomenon, including regressive autism, setback autism, and developmental stagnation. The validity of this distinction remains controversial; it is possible that regressive autism is a specific subtype.[22][23][24]

Characteristics

Autism is distinguished by a pattern of symptoms rather than one single symptom. The main characteristics are impairments in social interaction, impairments in communication, restricted interests and repetitive behavior. Other aspects, such as atypical eating, are also common but are not essential for diagnosis.[25] Individual symptoms of autism occur in the general population and appear not to associate highly, without a sharp line separating pathological severity from common traits.[26]

Social development

People with autism have social impairments and often lack the intuition about others that many people take for granted. Noted autistic Temple Grandin described her inability to understand the social communication of neurotypicals as leaving her feeling “like an anthropologist on Mars”.[27]

Social impairments become apparent early in childhood and continue through adulthood. Autistic infants show less attention to social stimuli, smile and look at others less often, and respond less to their own name. Autistic toddlers have more striking social deviance; for example, they have less eye contact and anticipatory postures and are more likely to communicate by manipulating another person’s hand.[24] Three- to five-year-old autistic children are less likely to exhibit social understanding, approach others spontaneously, imitate and respond to emotions, communicate nonverbally, and take turns with others. However, they do form attachments to their primary caregivers.[28] They display moderately less attachment security than usual, although this feature disappears in children with higher mental development or less severe ASD.[29] Older children and adults with ASD perform worse on tests of face and emotion recognition.[30]

Contrary to common belief, autistic children do not prefer to be alone. Making and maintaining friendships often proves to be difficult for those with autism. For them, the quality of friendships, not the number of friends, predicts how lonely they are.[31]

There are many anecdotal reports, but few systematic studies, of aggression and violence in individuals with ASD. The limited data suggest that in children with mental retardation, autism is associated with aggression, destruction of property, and tantrums. Dominick et al. Interviewed the parents of 67 children with ASD and reported that about two-thirds of the children had periods of severe tantrums and about one-third had a history of aggression, with tantrums significantly more common than in children with a history of language impairment.[32]

Communication

About a third to a half of individuals with autism do not develop enough natural speech to meet their daily communication needs.[33] Differences in communication may be present from the first year of life, and may include delayed onset of babbling, unusual gestures, diminished responsiveness, and the desynchronization of vocal patterns with the caregiver. In the second and third years, autistic children 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 are more likely to simply repeat others’ words (echolalia)[23][34] or reverse pronouns.[35] Joint attention seems to be necessary for functional speech, and deficits in joint attention seem to distinguish infants with ASD:[1] for example, they may look at a pointing hand instead of the pointed-at object,[24][34] and they consistently fail to point to “comment” about or “share” an experience at age-appropriate times.[1] Autistic children may have difficulty with imaginative play and with developing symbols into language.[23][34]

In a pair of studies, high-functioning autistic children aged 8–15 performed equally well, and adults better than individually matched controls at basic language tasks involving vocabulary and spelling. Both autistic groups performed worse than controls at complex language tasks such as figurative language, comprehension and inference. As people are often sized up initially from their basic language skills, these studies suggest that people speaking to autistic individuals are more likely to overestimate what their audience comprehends.[36]

Repetitive behavior
A young boy with autism, and the precise line of toys he made
A young boy with autism, and the precise line of toys he made

Autistic individuals display many forms of repetitive or restricted behavior, which the Repetitive Behavior Scale-Revised (RBS-R)[37] categorizes as follows.

* Stereotypy is apparently purposeless movement, such as hand flapping, head rolling, or body rocking.
* Comp

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Question?: What Is Autism

George asks…

What is the best current explanation for autism?

I asked my psychology professor about what causes autism from a neurological perspective, and he said that if he could answer that question, he’d get a Nobel Prize. However, there must be many hypotheses regarding this question, so which one is the most plausible?

admin answers:

It’s principally genetic, (but not one single “gene for autism!) though there seems to be some variation which requires the influence of environmental factors.
The two most considered at present are variations in womb temperature, and in foetal steroid and non-steroid hormones,
(not toxins or infections, diseases etc.)
Neither of these strands have progressed beyond hypothesis, unless my reading is out-of-date.

I’m working from information in Simon-Baron Cohen’s Autism and Asperger Syndrome (2009)
He cites six strands of evidence pointing to genetics as the major and critical component.

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Question?: Pdd Nos Symptoms

George asks…

Poll: Do you think vaccines cause or contribute to autism?

I’m curious to see what people really think.

admin answers:

No i dont believe they do whatsoever! I think parents are just being over cautious and flipping out for no reason. Vaccines have been around for ages, and now they are trying to say that it causes autisim? I dont think so. Dont you think there would have been more causes of that if it was actually linked to the vaccines. Its the same vaccine schedule, its not like the vaccines have changed much in the last 50 years.

Autism and autism spectrum disorders are complex neurodevelopmental disorders.Heritability contributes about 90% of the risk of a child developing autism, but the genetics of autism are complex and typically it is unclear which genes are responsible.Many other causes have been proposed, such as exposure of children to vaccines; these proposals are controversial and the vaccine hypotheses have no convincing scientific evidence.

Autism is a condition involving abnormalities of brain development and behavior which manifests itself before a child is three years old and has a steady course with no remission. It is characterized by impairments in social interaction and communication, as well as restricted and repetitive behavior. It is part of a larger family called the autism spectrum disorders (ASD) or pervasive developmental disorders (PDD), which include closely related syndromes such as Asperger syndrome and PDD-NOS. This article uses autism to denote the classic autistic disorder and ASD to denote the wider family.

Autism’s theory of causation is still incomplete. It has long been presumed that there is a common cause at the genetic, cognitive, and neural levels for autism’s characteristic triad of symptoms. However,here is increasing suspicion among researchers that autism does not have a single cause, but is instead a complex disorder with a set of core aspects that have distinct causes. Although these distinct causes have been hypothesized to often co-occur, it has also been suggested that the correlation between the causes has been exaggerated.The number of people known to have autism has increased dramatically since the 1980s, at least partly due to changes in diagnostic practice; it is unknown whether prevalence has increased as well. An increase in prevalence would suggest directing more attention and funding toward changing environmental factors instead of continuing to focus on genetics.

The consensus among mainstream autism researchers is that genetic factors predominate, but some are concerned, as one anonymous researcher put it, that “geneticists are running the show, and ignoring the environmental aspects.”Environmental factors that have been claimed to contribute to autism or exacerbate its symptoms, or may be important to consider in future research, include certain foods, infectious disease, heavy metals, solvents, diesel exhaust, PCBs, phthalates and phenols used in plastic products, pesticides, brominated flame retardants, alcohol, smoking, illicit drugs, and vaccines. Among these factors, vaccines have attracted much attention, as parents may first become aware of autistic symptoms in their child around the time of a routine vaccination, and parental concern about vaccines has led to a decreasing uptake of childhood immunizations and an increasing likelihood of measles outbreaks. However, as described in Mercury and MMR vaccine below, there is overwhelming scientific evidence showing no causal association between the measles-mumps-rubella vaccine and autism, and there is no scientific evidence that the vaccine preservative thiomersal helps cause autism.

In 2007 the National Institutes of Health announced an Autism Centers of Excellence (ACE) research program to find the causes of autism and identify new treatments for the disorder. Initial recipients are focusing on genetic factors, brain imaging, brain chemicals and functions including mirror neurons, effect on early parent-child behavior on autism, and learning in autistic children.
Http://en.wikipedia.org/wiki/Causes_of_autism

I am a mother of a 12 month old boy… Who is up to date on all his vaccines so far. And he will continue to get all his vaccinations. As so will any other children i should have. Im sorry but i wouldnt take the risk of my child actually contracting one of those disease just because some parents believe that it may be linked to autisim. Sorry, i would rather have my child vaccinated.

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