Autism is a disorder of neural development characterized by impaired social interaction and communication, and repetitive behavior. These signs all begin before a child is three years old.
Autism affects information processing in the brain by altering how nerve cells and their synapses connect and organize; how this occurs is not well understood.
It is one of three recognized disorders in the autism spectrum (ASDs), the other two being Asperger syndrome, which lacks delays in cognitive development and language, and Pervasive Developmental Disorder-Not Otherwise Specified (commonly abbreviated as PDD-NOS), which is diagnosed when the full set of criteria for autism or Asperger syndrome are not met.
In rare cases, autism is strongly associated with agents that cause birth defects.
Although there is no known cure, early behavioral or cognitive intervention can help autistic children gain self-care, social, and communication skills.
Not many children with autism live independently after reaching adulthood, though some become successful.
Autism is a highly variable neurodevelopment disorder that first appears during infancy or childhood, and generally follows a steady course without remission. Overt symptoms gradually begin after the age of six months, become established by age two or three years, and tend to continue through adulthood, although often in more muted form.
It is distinguished not by a single symptom, but by a characteristic triad of symptoms: impairments in social interaction; impairments in communication; and repetitive behavior. Other aspects, such as atypical eating, are also common but are not essential for diagnosis.
Autistic children are less likely to make requests or share experiences, and are more likely to simply repeat others’ words or reverse pronouns.
Autistic children may have difficulty with imaginative play and with developing symbols into language.
In a pair of studies, high-functioning autistic children aged 8–15 performed equally well as, 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
Autistic individuals display many forms of repetitive behavior, which the Repetitive Behavior Scale-Revised (RBS-R) categorizes as follows.
A young boy with autism, and the precise line of toys he made
Stereotypy is repetitive movement, such as hand flapping, making sounds, head rolling, or body rocking.
Ritualistic behavior involves an unvarying pattern of daily activities, such as an unchanging menu or a dressing ritual.Restricted behavior is limited in focus, interest, or activity, such as preoccupation with a single television program, toy, or game.
Autistic individuals may have symptoms that are independent of the diagnosis, but that can affect the individual or the family.
An estimated 0.5% to 10% of individuals with ASD show unusual abilities, ranging from splinter skills such as the memorization of trivia to the extraordinarily rare talents of prodigious autistic savants.
Many individuals with ASD show superior skills in perception and attention, relative to the general population.
Sensory abnormalities are found in over 90% of those with autism, and are considered core features by some, although there is no good evidence that sensory symptoms differentiate autism from other developmental disorders.
Unusual eating behavior occurs in about three-quarters of children with ASD, to the extent that it was formerly a diagnostic indicator.
Selectivity is the most common problem, although eating rituals and food refusal also occur; this does not appear to result in malnutrition.
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, there is increasing suspicion that autism is instead a complex disorder whose core aspects have distinct causes that often co-occur.
Deletion (1), duplication (2) and inversion (3) are all chromosome abnormalities that have been implicated in autism.
Autism has a strong genetic basis, although the genetics of autism are complex and it is unclear whether ASD is explained more by rare mutations with major effects, or by rare multigene interactions of common genetic variants.
Complexity arises due to interactions among multiple genes, the environment, and epigenetic factors which do not change DNA but are heritable and influence gene expression.
However, 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 like fragile X syndrome, and none of the genetic syndromes associated with ASDs have been shown to selectively cause ASD.
Numerous candidate genes have been located, with only small effects attributable to any particular gene. The large number of autistic individuals with unaffected family members may result from copy number variations—spontaneous deletions or duplications in genetic material during meiosis.
Hence, 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.
Several lines of evidence point to synaptic dysfunction as a cause of autism.
Some rare mutations may lead to autism by disrupting some synaptic pathways, such as those involved with cell adhesion.
Gene replacement studies in mice suggest that autistic symptoms are closely related to later developmental steps that depend on activity in synapses and on activity-dependent changes.
All known teratogens (agents that cause birth defects) related to the risk of autism appear to act during the first eight weeks from conception, and though this does not exclude the possibility that autism can be initiated or affected later, it is strong evidence that autism arises very early in development.
About half of parents of children with ASD notice their child’s unusual behaviors by age 18 months, and about four-fifths notice by age 24 months. As postponing treatment may affect long-term outcome, any of the following signs is reason to have a child evaluated by a specialist without delay:
No babbling by 12 months.
No gesturing by 12 months.
No single words by 16 months.
No two-word spontaneous phrases (other than instances of echolalia) by 24 months.
Any loss of any language or social skills, at any age.
US and Japanese practice is to screen all children for ASD at 18 and 24 months, using autism-specific formal screening tests.
It may be more accurate to precede these tests with a broadband screener that does not distinguish ASD from other developmental disorders.
Screening tools designed for one culture’s norms for behaviors like eye contact may be inappropriate for a different culture.
Although genetic screening for autism is generally still impractical, it can be considered in some cases, such as children with neurological symptoms and dysmorphic features.
Diagnosis is based on behavior, not cause or mechanism. Autism is defined in the DSM-IV-TR as exhibiting at least six symptoms total, including at least two symptoms of qualitative impairment in social interaction, at least one symptom of qualitative impairment in communication, and at least one symptom of restricted and repetitive behavior.
Sample symptoms include lack of social or emotional reciprocity, stereotyped and repetitive use of language or idiosyncratic language, and persistent preoccupation with parts of objects.
Onset must be prior to age three years, with delays or abnormal functioning in either social interaction, language as used in social communication, or symbolic or imaginative play.
The disturbance must not be better accounted for by Rett syndrome or childhood disintegrative disorder.
ICD-10 uses essentially the same definition.
Several diagnostic instruments are available. Two are commonly used in autism research: the Autism Diagnostic Interview-Revised (ADI-R) is a semistructured parent interview, and the Autism Diagnostic Observation Schedule (ADOS) uses observation and interaction with the child.
The Childhood Autism Rating Scale (CARS) is used widely in clinical environments to assess severity of autism based on observation of children.
A pediatrician commonly performs a preliminary investigation by taking developmental history and physically examining the child.
If warranted, diagnosis and evaluations are conducted with help from ASD specialists, observing and assessing cognitive, communication, family, and other factors using standardized tools, and taking into account any associated medical conditions.
A pediatric neuropsychologist is often asked to assess behavior and cognitive skills, both to aid diagnosis and to help recommend educational interventions.
A differential diagnosis for ASD at this stage might also consider mental retardation, hearing impairment, and a specific language impairmentsuch as Landau–Kleffner syndrome.
The presence of autism can make it harder to diagnose coexisting psychiatric disorders such as depression.
Clinical genetics evaluations are often done once ASD is diagnosed, particularly when other symptoms already suggest a genetic cause.
Although genetic technology allows clinical geneticists to link an estimated 40% of cases to genetic causes, consensus guidelines in the US and UK are limited to high-resolution chromosome and fragile X testing.
A genotype-first model of diagnosis has been proposed, which would routinely assess the genome’s copy number variations.
As new genetic tests are developed several ethical, legal, and social issues will emerge. Commercial availability of tests may precede adequate understanding of how to use test results, given the complexity of autism’s genetics.
Metabolic and neuroimaging tests are sometimes helpful, but are not routine.
ASD can sometimes be diagnosed by age 14 months, although diagnosis becomes increasingly stable over the first three years of life
Although the symptoms of autism and ASD begin early in childhood, they are sometimes missed; years later, adults may seek diagnoses to help them or their friends and family understand themselves, to help their employers make adjustments, or in some locations to claim disability living allowances or other benefits.
Underdiagnosis and overdiagnosis are problems in marginal cases, and much of the recent increase in the number of reported ASD cases is likely due to changes in diagnostic practices. The increasing popularity of drug treatment options and the expansion of benefits has given providers incentives to diagnose ASD, resulting in some overdiagnosis of children with uncertain symptoms.
Conversely, the cost of screening and diagnosis and the challenge of obtaining payment can inhibit or delay diagnosis. It is particularly hard to diagnose autism among the visually impaired, partly because some of its diagnostic criteria depend on vision, and partly because autistic symptoms overlap with those of common blindness syndromes or blindisms.
No cure is known.
Children recover occasionally, so that they lose their diagnosis of ASD; this occurs sometimes after intensive treatment and sometimes not.
It is not known how often recovery happens; reported rates in unselected samples of children with ASD have ranged from 3% to 25%.
Most autistic children can acquire language by age 5 or younger, though a few have developed communication skills in later years.
Most children with autism lack social support, meaningful relationships, future employment opportunities or self-determination.
Although core difficulties tend to persist, symptoms often become less severe with age. Few high-quality studies address long-term prognosis. Some adults show modest improvement in communication skills, but a few decline; no study has focused on autism after midlife.
Acquiring language before age six, having an IQ above 50, and having a marketable skill all predict better outcomes; independent living is unlikely with severe autism.
Several other conditions are common in children with autism.
Genetic disorders. 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.
Mental retardation. The fraction of autistic individuals who also meet criteria for mental retardation has been reported as anywhere from 25% to 70%, a wide variation illustrating the difficulty of assessing autistic intelligence. For ASD other than autism, the association with mental retardation is much weaker.
Anxiety disorders are common among children with ASD; there are no firm data, but studies have reported prevalences ranging from 11% to 84%. Many anxiety disorders have symptoms that are better explained by ASD itself, or are hard to distinguish from ASD’s symptoms.
Epilepsy with variations in risk of epilepsy due to age, cognitive level, and type of language disorder.
Several metabolic defects, such as phenylketonuria, are associated with autistic symptoms.
PROJECT:1. Project on ‘’JATROPHA CULTIVATION, THE FUTURE PROSPECTIVE OF BIODIESEL- A CASE STUDY IN RASGOVINDPUR BLOCK OF MAYURBHANJ DISTRICT” at North Orissa University in 2008.2. Project on ‘’ENUMERATION OF SIX MAJOR GROUPS OF BACTERIA FROM MANGROOVE SOILS OF BHITARKANIKA‘’at North Orissa University in 2009. PUBLICATIONS: ONLINE ARTICLE PUBLICATIONS: http://www.articlesbase.com/health-articles/medicinal-value-of-allium-sativum-3533903.html http://www.articlesbase.com/health-articles/medicinal-value-of-aloe-vera-3596754.html http://www.articlesbase.com/diseases-and-conditions-articles/thalassemia-causes-and-treatments-3723551.html SEMINAR GIVEN: AWARDS:TRAINING: