Autism

Autism
ICD-10	ICD10 F84.0-F84.1
ICD-9	299.0
OMIM	209850
MedlinePlus	001526

Autism is classified by the World Health Organization and American Psychological Association as a developmental disability that results from a disorder of the human central nervous system. It is diagnosed using specific criteria for impairments to social interaction, communication, interests, imagination and activities. The causes, symptoms, etiology, treatment, and other issues are controversial.

Autism manifests itself "before the age of three years" according to the World Health Organization's International Classification of Diseases (ICD-10) Autistic children are marked by delays in their "social interaction, language as used in social communication, or symbolic or imaginative play" (Diagnostic and Statistical Manual of Mental Disorders).

Autism, and the other four pervasive developmental disorders (PDD), are all considered to be neurodevelopmental disorders. They are diagnosed on the basis of a triad, or group of three behavioral impairments or dysfunctions: 1. impaired social interaction, 2. impaired communication and 3. restricted and repetitive interests and activities. These three basic characteristics reflect Dr. Leo Kanner's first reports of autism emphasizing "autistic aloneness" and "insistence on sameness."

From a physiological standpoint, autism is often less than obvious in that outward appearance may not indicate a disorder. Diagnosis typically comes from a complete patient history and physical and neurological evaluation.

The incidence of diagnosed autism has increased since the 1990s. Reasons offered for this phenomenon include better diagnosis, wider public awareness of the condition, regional variations in diagnostic criteria, or simply an increase in the occurrence of ASD (autism spectrum disorders). The United States Centers for Disease Control (CDC) estimate the prevalence of autism spectrum disorders to be about one in every 150 children. In 2005, the National Institute of Mental Health (NIMH) stated the "best conservative estimate" as 1 in 1000. In 2006, NIMH estimated that the incidence was 2-6 in every 1000

There are numerous theories as to the specific causes of autism, but they are as yet unproven (see section on "Causes" below). Proposed factors include genetic influence, anatomical variations (e.g. head circumference), abnormal blood vessel function and oxidative stress. Their significance as well as implications for treatment remain speculative.

Conversely, some autistic children and adults are opposed to attempts to cure autism. These people see autism as part of who they are, and in some cases they perceive treatments and attempts of a cure to be unethical.

History

The word autism was first used in the English language by Swiss psychiatrist Eugene Bleuler in a 1912 issue of the American Journal of Insanity. It comes from the Greek word for "self," αυτος (autos). Autism was actually confused with schizophrenia during the early stages of observation. Bleuler used the term to describe the schizophrenics' seeming difficulty in connecting with other people.

However, the classification of autism as a separate disorder or disease did not occur until 1943 when psychiatrist Dr. Leo Kanner of the Johns Hopkins Hospital in Baltimore reported on 11 child patients with striking behavioral similarities and introduced the label "early infantile autism." He suggested the term "autism" to describe the fact that the children seemed to lack interest in other people. Kanner's first paper on the subject was published in a now defunct journal called The Nervous Child, and almost every characteristic he originally described is still regarded as typical of the autistic spectrum of disorders.

At the same time, an Austrian scientist named Dr. Hans Asperger made similar observations, although his name has since become attached to a different higher-functioning form of autism known as Asperger syndrome. Widespread recognition of Asperger's work was delayed by World War II in Germany, and by his seminal paper not being translated into English for almost 50 years. The majority of his work was not widely read until 1997.

Autism and Asperger's Syndrome are today listed in the DSM-IV-TR as two of the five pervasive developmental disorders (PDD), which also include Childhood disintegrative disorder, Rett syndrome and Pervasive Developmental Disorder Not Otherwise Specified (or atypical autism). Health care providers also refer to autism spectrum disorders (ASD) which includes only three of those listed in PDD: Autistic disorder, Asperger syndrome, Pervasive Developmental Disorder Not Otherwise Specified. All of these conditions are characterized by varying degrees of deficiencies in communication skills and social interactions, along with restricted, repetitive, and stereotyped patterns of behavior.

Characteristics

On the surface, individuals who have autism are physically indistinguishable from those without. Some studies show that autistic children tend to have larger head circumferences but the significance in the disorder is unclear. Sometimes autism co-occurs with other disorders, and in those cases outward differences may be apparent.

Individuals diagnosed with autism can vary greatly in skills and behaviors, and their response to sensory input shows marked differences in a number of ways from that of other people. Certain stimulations, such as sounds, lights, and touch, will often affect someone with autism differently than someone without, and the degree to which the sensory system is affected can vary greatly from one individual to another.

Key behaviors

Autistic children may display unusual behaviors or fail to display expected behaviors. Normal behaviors may develop at the appropriate age and then disappear or, conversely, are delayed and develop quite some time after normal occurrence. In assessing developmental delays, different physicians may not always arrive at the same conclusions. Much of this difference between diagnosis is due to the disputed criteria for autism. Deciding how a child should behave is also difficult because diagnostic tests have to be objective, which is not a simple thing to accomplish. Because of this practitioners and researchers in pediatrics, child psychology, behavior analysis, and child development are always looking for early indicators of autism.

The diagnosis of autism must meet specific criterion but there are also many characteristics that are idiosyncratic. Thus, Autism is not a "one size fits all" label. In other words the spectrum disorder encompasses a very wide range of behaviors and symptoms.

Some behaviors cited by the National Institute of Child Health and Human Development (listed below) may simply mean a normal delay in one or more areas of development, while others are more typical of ASDs—Autistic Spectrum Disorders.

The list below is not all-inclusive, and generally applies to children and not adults. Furthermore, while some of these behaviors might be seen in a person with autism, others may be absent.

Noted behaviours

• does not respond to his/her name.
• cannot explain what he/she wants.
• language skills are slow to develop or speech is delayed.
• doesn't follow directions.
• will fuss if didn't get what wanted.
• at times, the child seems to be deaf.
• seems to hear sometimes, but not other times.
• doesn't point or wave "bye-bye."
• doesn't understand the concept of pointing; will look at the hand pointing rather than the object being pointed at.
• used to say a few words or babble, but now he/she doesn't.
• throws intense or violent tantrums.
• has odd movement patterns.
• likes to spin around in a circle.
• likes being in a place well known.
• hands on ears oftenly.
• is overly active, uncooperative, or resistant.
• doesn't know how to play with toys.
• doesn't smile when smiled at.
• has poor eye contact.
• gets "stuck" doing the same things over and over and can't move on to other things.
• seems to prefer to play alone.
• gets things for him/herself only.
• is very independent for his/her age.
• does things "early" compared to other children.
• seems to be in his/her "own world."
• seems to tune people out.
• is not interested in other children.
• dislikes playing pretend.
• walks on his/her toes.
• shows unusual attachments to toys, objects, or schedules (i.e., always holding a string or having to put socks on before pants).
• spends a lot of time stacking objects, lining things up or putting things in a certain order.
• unconcerned about - or completely oblivious to - dangers around him/her (i.e., standing in the middle of the street without worrying about getting hit by a car).

Autism and blindness

The characteristics of a person with both an Autism Spectrum Disorder (ASD) and a severe visual impairment (VI) may vary from a person with just ASD or just VI. Historically, many behaviors of blind children were seen as "autistic-like" but were attributed to their blindness rather than pursuing possibilities of autism.

Developmental trajectories of children with ASD-VI are often very similar as those followed by children with typical autism, but the child with ASD-VI will have particularly unusual responses to sensory information. The person may be overly sensitive to touch or sound, or be less responsive to pain. Typically, touch, smell, and sound are affected the most dramatically.

Communication difficulties

Template:Citations missing Some people with autism demonstrate advanced cognitive ability, but lack communicative skills or are not inclined to interact with others socially. An example of this is the noted autistic Temple Grandin, who holds a PhD and is a successful developer of livestock handling technologies. She describes her inability to understand the social communication of neurotypicals as leaving her feeling "like an anthropologist on Mars." Grandin's case was described by neurologist Oliver Sacks in his 1995 book titled An Anthropologist on Mars: Seven Paradoxical Tales. Another person with extreme autism is author Tito Mukhopadhyay, one of whose books is The Mind Tree.

Perhaps due to their difficulties communicating with other humans, some autistics have gravitated toward working with animals. Temple Grandin describes her observations and theories about animals, taken from her work with cattle. Dawn Prince-Hughes, diagnosed with Asperger's, describes her observations of gorillas in Songs of the Gorilla Nation.

Some infants who later show signs of autism coo and babble during the first few months of life, but stop soon afterwards. Others may be delayed, developing language as late as the teenage yearsTemplate:Fact. Still, inability to speak does not mean that people with autism are unintelligent or unaware. Once given appropriate accommodations, some will happily converse for hours, and can often be found in online chat rooms, discussion boards or websites and even using communication devices at autism-community social events such as Autreat.

Sometimes, the body language of people with autism can be difficult for other people to understand. Facial expressions, movements, and gestures may be easily understood by some other people with autism, but do not match those used by other people. Also, their tone of voice has a much more subtle inflection in reflecting their feelings, and the auditory system of a person without autism often cannot sense the fluctuations. What seems to non-autistic people like odd prosody; things like a high-pitched, sing-song, or flat, robot-like voice may be common in autistic children and some will have combinations of these prosody issues. Some autistic children with relatively good language skills speak like little adults, rather than communicating at their current age level, which is one of the things that can lead to problems.

Since non-autistic people are often unfamiliar with the autistic body language, and since autistic natural language may not tend towards speech, autistic people often struggle to let other people know what they need. As anybody might do in such a situation, they may scream in frustration or resort to grabbing what they want. While waiting for non-autistic people to learn to communicate with them, people with autism do whatever they can to get through to them. Communication difficulties may contribute to autistic people becoming socially anxious or depressed or prone to self-injurious behaviors. Recently, with the awareness that those with autism can have more than one condition, a significant percentage of people with autism are being diagnosed with co-morbid mood, anxiety and compulsive disorders which may also contribute to behavioral and functioning challenges.

Repetitive behaviors

Although people with autism usually appear physically normal, unusual repetitive motions, known as self-stimulation or "stimming," may set them apart. These behaviors might be extreme or subtle. Some children and older individuals spend a lot of time repeatedly flapping their arms or wiggling their toes, others suddenly freeze in position. Some spend hours arranging objects in a certain way rather than engaging in pretend play as a typical child might, and becoming agitated if they are re-arranged or moved. Repetitive behaviors can also extend into the spoken word; perseveration of a single word or phrase can also become a part of the child's daily routine. Some may repeat words from movies and watch certain bits over and over again. Autistic children may demand consistency in their environment. A slight change in the timing, format or route of a routine or trip can be extremely disturbing to them. Template:Fact. Autistics sometimes have persistent, intense preoccupations. For example, the child might be obsessed with learning all about computers, television programs, lighthouses or virtually any other topic.

Effects in education

Children with autism are affected by their symptoms every day, which set them apart from unaffected students. Because of problems with receptive language and theory of mind, they can have difficulty understanding some classroom directions and instruction, along with subtle vocal and facial cues of teachers. This inability to fully decipher the world around them often makes education stressful. Teachers need to be aware of a student's disorder, and ideally should have specific training in autism education, so that they are able to help the student get the best out of his or her classroom experiences.

Some students learn more effectively with visual aids as they are better able to understand material presented visually. Because of this, many teachers create “visual schedules” for their autistic students. This allows students to concretely see what is going on throughout the day, so they know what to prepare for and what activity they will be doing next. Some autistic children have trouble going from one activity to the next, so this visual schedule can help to reduce stress.

Research has shown that working in pairs may be beneficial to autistic children. Autistic students have problems not only with language and communication, but with socialization as well. By facilitating peer interaction, teachers can help their students with autism make friends, which in turn can help them cope with problems or understand the world around them. This can help them to become more integrated into the mainstream environment of the classroom.

A teacher's aide can also be useful to the student. The aide is able to give more elaborate directions that the teacher may not have time to explain to the autistic child and can help the child to stay at an equivalent level to the rest of the class through the special one-on-one instruction. However, some argue that students with one-on-one aides may become overly dependent on the help, thus leading to difficulty with independence later on.

There are many different techniques that teachers can use to assist their students. A teacher needs to become familiar with the child’s disorder to know what will work best with that particular child. Every child is going to be different and teachers have to be able to adjust with every one of them.

Students with autism spectrum disorders sometimes have high levels of anxiety and stress, particularly in social environments like school. If a student exhibits aggressive or explosive behavior, it is important for educational teams to recognize the impact of stress and anxiety. Preparing students for new situations, such as through writing social stories, can lower anxiety. Teaching social and emotional concepts using systematic teaching approaches such as The Incredible 5-Point Scale or other cognitive behavioral strategies can increase a student's ability to control excessive behavioral reactions.

DSM definition

Autism is defined in section 299.00 of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) as:

1. A total of six (or more) items from (1), (2) and (3), with at least two from (1), and one each from (2) and (3):
   1. qualitative impairment in social interaction, as manifested by at least two of the following:
      1. marked impairment in the use of multiple nonverbal behaviors such as eye-to-eye gaze, facial expression, body postures, and gestures to regulate social interaction
      2. failure to develop peer relationships appropriate to developmental level
      3. a lack of spontaneous seeking to share enjoyment, interests, or achievements with other people (e.g., by a lack of showing, bringing, or pointing out objects of interest)
      4. lack of social or emotional reciprocity
   2. qualitative impairments in communication as manifested by at least one of the following:
      1. delay in, or total lack of, the development of spoken language (not accompanied by an attempt to compensate through alternative modes of communication such as gesture or mime)
      2. in individuals with adequate speech, marked impairment in the ability to initiate or sustain a conversation with others
      3. stereotyped and repetitive use of language or idiosyncratic language
      4. lack of varied, spontaneous make-believe play or social imitative play appropriate to developmental level
   3. restricted repetitive and stereotyped patterns of behavior, interests, and activities, as manifested by at least one of the following:
      1. encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus
      2. apparently inflexible adherence to specific, nonfunctional routines or rituals
      3. stereotyped and repetitive motor mannerisms (e.g., hand or finger flapping or twisting, or complex whole-body movements)
      4. persistent preoccupation with parts of objects
2. Delays or abnormal functioning in at least one of the following areas, with onset prior to age 3 years:
   1. social interaction
   2. language as used in social communication
   3. symbolic or imaginative play.
3. The disturbance is not better accounted for by Rett's Disorder or Childhood Disintegrative Disorder.

These are rules of thumb and may not necessarily apply to all diagnosed autistics.

Types of autism

Autism presents in a wide degree, from those who are nearly dysfunctional and apparently mentally disabled to those whose symptoms are mild or remedied enough to appear unexceptional ("normal") to others. Although not used or accepted by professionals or within the literature, autistic individuals are often divided into those with an IQ<80 referred to as having "low-functioning autism" (LFA), while those with IQ>80 are referred to as having "high-functioning autism" (HFA). Low and high functioning are more generally applied to how well an individual can accomplish activities of daily living, rather than to IQ. The terms low and high functioning are controversial and not all autistics accept these labels. Additionally, a recent review questioned the validity of IQ testing of autistic people.

This discrepancy can lead to confusion among service providers who equate IQ with functioning and may refuse to serve high-IQ autistic people who are severely compromised in their ability to perform daily living tasks, or may fail to recognize the intellectual potential of many autistic people who are considered LFA. For example, some professionals refuse to recognize autistics who can speak or write as being autistic at all, because they still think of autism as a communication disorder so severe that no speech or writing is possible.

As a consequence, many "high-functioning" autistic persons, and autistic people with a relatively high IQ, are under diagnosed, thus making the claim that "autism implies retardation" self-fulfilling. The number of people diagnosed with LFA is not rising quite as sharply as HFA, indicating that at least part of the explanation for the apparent rise is probably better diagnostics. Many also think that ASD's are being over diagnosed: (1) because the growth in the number and complexity of symptoms associated with autism has increased the chances professionals will erroneously diagnose autism and (2) because the growth in services and therapies for autism has increased the number who falsely qualify for those often free services and therapies.

Asperger's and Kanner's syndromes

File:Asperger kl2.jpg

Dr. Hans Asperger described a form of autism in the 1940s that later became known as Asperger syndrome.

In the current Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR), the most significant difference between Autistic Disorder (also known as Kanner's syndrome) and Asperger's syndrome is that a diagnosis of the former includes the observation of "delays or abnormal functioning in at least one of the following areas, with onset prior to age 3 years: (1) social interaction, (2) language as used in social communication, or (3) symbolic or imaginative play", while a diagnosis of Asperger's syndrome observes "no clinically significant delay" in the latter two of these areas.

While the DSM-IV does not include level of intellectual functioning in the diagnosis, the fact that those with Asperger's syndrome tend to perform better than those with Kanner's autism has produced a popular conception that Asperger's syndrome is synonymous with "higher-functioning autism", or that it is a lesser disorder than autism. Similarly, there is a popular conception that autistic individuals with a high level of intellectual functioning in fact have Asperger's syndrome, or that both types are merely 'geeks' with a medical label. The popular depiction of autism in the media has been of relatively severe cases (for example, as seen in the films Rain Man and Mercury Rising), and in turn many close friends and relatives of those who have been diagnosed in the autistic spectrum choose to speak of their loved ones as having Asperger's syndrome rather than autism.

The extent to which someone with higher functioning autism or Asperger's syndrome may excel is theoretically quite high. For example, Henry Cavendish, one of history's foremost scientists, may have been autistic. George Wilson, a notable chemist and physician, wrote a book about Cavendish entitled, "The Life of the Honourable Henry Cavendish", published in 1851. From Wilson's detailed description it seems that while Cavendish may have exhibited many classic signs of autism, he nevertheless had an extraordinary mind.

Autism as a spectrum disorder

Template:Details Another view of these disorders is that they are on a continuum known as autistic spectrum disorders. Autism spectrum disorder is an increasingly popular term that refers to a broad definition of autism including the classic form of the disorder as well as closely related conditions such as PDD-NOS and Asperger's syndrome. Although the classic form of autism can be easily distinguished from other forms of autism spectrum disorder, the terms are often used interchangeably.

A related continuum, Sensory Integration Dysfunction, involves how well humans integrate the information they receive from their senses. Autism, Asperger's syndrome, and Sensory Integration Dysfunction are all closely related and overlap.

Some people believe that there might be two manifestations of classical autism, regressive autism and early infantile autism. Early infantile autism is present at birth while regressive autism begins before the age of 3 and often around 18 months. Although this causes some controversy over when the neurological differences involved in autism truly begin, some speculate that an environmental influence or toxin triggers the disorder. This triggering could occur during gestation due to a toxin that enters the mother's body and is transferred to the fetus. The triggering could also occur after birth during the crucial early nervous system development of the child.

A paper published in 2006 concerning the behavioral, cognitive, and genetic bases of autism argues that autism should perhaps not be seen as a single disorder, but rather as a set of distinct symptoms (social difficulties, communicative difficulties and repetitive behaviors) that have their own distinct causes. An implication of this would be that a search for a "cure" for autism is unlikely to succeed if it is not examined as separate, albeit overlapping and commonly co-occurring, disorders.

Epidemiology

Further information: Frequency of autism and Autism (incidence).

Gender differences

There is not a clear-cut ratio of incidence between males and females. Studies have found much higher prevalence in males at the high-functioning end of the spectrum, while the ratios appear to be closer to 1:1 at the low-functioning end. In addition, a study published in 2006 suggested that males over 40 are more likely than younger males to parent a child with autism, and that the ratio of autism incidence in males and females is closer to 1:1 with older fathers.

Reported increase with time

The number of reported cases of autism increased dramatically over a decade. Statistics in graph from the National Center for Health Statistics.

There was a worldwide increase in reported cases of autism over the decade to 2006. There are several theories about the apparent sudden increase.

Many epidemiologists argue that the rise in the incidence of autism in the United States is largely attributable to a broadening of the diagnostic concept, reclassifications, public awareness, and the incentive to receive federally mandated services. However, some authors indicate that the existence of an as yet unidentified contributing environmental risk factor cannot be ruled out. On the other hand, a widely-cited pilot study conducted in California by the UC Davis M.I.N.D. Institute (17 October 2002), reported that the increase in autism in California is real, even after accounting for changes to diagnostic criteria.

The question of whether the rise in incidence is real or an artifact of improved diagnosis and a broader concept of autism remains controversial. Dr. Chris Johnson, a professor of pediatrics at the University of Texas Health Sciences Center at San Antonio and co-chair of the American Academy of Pediatrics Autism Expert Panel, sums up the state of the issue by saying, "There is a chance we're seeing a true rise, but right now I do not think anybody can answer that question for sure." (Newsweek reference below).

The answer to this question has significant ramifications on the direction of research, since a real increase would focus more attention (and research funding) on the search for environmental factors, while the alternative would focus more attention to genetics. On the other hand, it is conceivable that certain environmental factors (such as chemicals, infections, medicines, vaccines, diet and societal changes) may have a particular impact on people with a specific genetic constitution.

One of the more popular theories is that there is a connection between "geekdom" and autism. This is hinted, for instance, by a Wired Magazine article in 2001 entitled "The Geek Syndrome", which is a point argued by many in the autism rights movement. This article, many professionals assert, is just one example of the media's application of mental disease labels to what is actually variant normal behavior—they argue that shyness, lack of athletic ability or social skills, and intellectual interests, even when they seem unusual to others, are not in themselves signs of autism or Asperger's syndrome. Others assert that children who in the past would have simply been accepted as a little different or even labeled 'gifted' are now being labeled with mental disease diagnoses. See clinomorphism for further discussion of this issue.

Due to the recent publicity surrounding autism and autistic spectrum disorders, an increasing number of adults are choosing to seek diagnoses of high-functioning autism or Asperger's syndrome in light of symptoms they currently experience or experienced during childhood. Since the cause of autism is thought to be at least partly genetic, a proportion of these adults seek their own diagnosis specifically as follow-up to their children's diagnoses. Because autism falls into the pervasive developmental disorder category, an individual's symptoms must have been present before age seven in order to make a strict differential diagnosis.

Treatment

Autism is sometimes considered to be untreatable, although this point has been disputed. There is a broad array of autism therapies with various goals, e.g. improving health and well-being, emotional problems, difficulties with communication and learning, and sensory problems for people with autism. The efficacy of each approach varies greatly from person to person.

Applied Behavior Analysis (ABA) is an approach in which tasks are systematically reduced to component parts and then reconstructed through repetition and positive reinforcement. The approach also attempts to identify and analyze behaviors that are harmful or that interfere with learning to ensure they are not reinforced. Ultimately the goal is to help children to succeed and become independent socially and academically.

Causes

The causes and etiology of autism are areas of debate and controversy; there is currently no consensus, and researchers are studying a wide range of possible genetic and environmental causes. Since autistic individuals are all somewhat different from one another, there are likely multiple "causes" that interact with each other in subtle and complex ways, and thus give slightly differing outcomes in each individual. Two environmental theories include the impact of vaccines on the immune system (of which a statistically significant link has never been found despite many attempts; see the vaccine theory sub-heading in the Causes of autism page for a more extensive treatment) and a more recent theory relating autism to high levels of television viewing while young.

Research claims also link autism with abnormal blood vessel function, and oxidative stress. This line of research may lead to new medical therapies.

Physiology and neurology

Autism appears to involve a greater amount of the brain than previously thought. A study of 112 children (56 with autism and 56 without), published in the Journal of Child Neuropsychology, found those with autism to have more problems with complex tasks, such as tying their shoelaces or writing, which suggests that many areas of the brain are involved. Children with autism performed simple tasks as well as or better than those without. In tests of visual and spatial skills, autistic children did well at finding small objects in complex pictures (e.g., finding the character Waldo in "Where's Waldo" pictures). However, they found it difficult to tell the difference between similar-looking people. Children with autism tended to do well in spelling and grammar, but found it much more difficult to understand complex speech, such as idioms or similes when the meaning of the phrase is figurative. They would, for example, not understand that "He kicked the bucket" meant someone had died, or were likely to actually hop if told to "hop to it".

The inference from this research, according to researchers at the Pittsburgh School of Medicine, is that "These findings show that you cannot compartmentalize autism. It's much more complex.”

The research from this perspective has a number of implications:

• Autism is more than likely a global disorder which affects how the brain processes the information it receives, while complex information tends to make this more readily apparent.
• Neurological ‘wiring’ in people with autism manifest abnormalities in the areas of the brain that communicate with each other.
• Observed abnormalities provide a reasonable explanation for why children with autism have problems with complex tasks which require multiple areas of the brain to work together; autistic people tend to do better in tasks that only require one region of the brain.
• The causes of autism are possibly more pervasive than previously believed; for example, more areas of the brain are affected than just those involving social interaction, communication, interests, and imagination.
• Autism may not be primarily a disorder of social interaction; research must now take into account non-social aspects.

A possible explanation for the characteristics of the syndrome is a variation in the way the brain itself reacts to sensory input and how parts of the brain then handle the information. An electroencephalographic (EEG) study of 36 adults (half of whom had autism) at Washington University in St. Louis found that adults with autism show differences in the manner in which neural activity is coordinated. The implication seems to be that there is poor internal communication between different areas of the brain. (Electroencephalographs, or EEGs, measure the activity of brain cells.)

The study indicated that there were abnormal patterns in the way the brain cells were connected in the temporal lobe of the brain. (The temporal lobe deals with language.) These abnormal patterns would seem to indicate inefficient and inconsistent communication inside the brain of autistic people.

Studies in neuropathology indicate abnormalities in the amygdala, hippocampus, septum, mamillary bodies, limbic system,and the cerebellum.

• Autistic brains are slightly larger and heavier and a larger than normal head circumference is commonly noted.
• In the limbic system, there is an excess of cells and they are too small. The neurons themselves appear to be underdeveloped. Dendritic trees which provide the basis for connections between neurons are truncated (i.e. shortened).
• In the cerebellum, purkinje cells are widely affected. The anatomic differences correlate to the curtailment of development earlier than 30 weeks gestation. In other words, the development of the cells appears to have stopped at some time before the 30th week in utero
• An enlarged third ventricle of the brain appears to accompany autism in those who are non-mentally retarded, but the reasons for this and its effects are still unknown.

Research has not yet established exactly what is specific to autism and what may be seen in other disorders however.

Individuals with autism are also far more likely to develop epilepsy than would otherwise be expected (estimated 10-30% incidence).

Genetic component

Genetic influence comprises a significant aspect of research in the causes of autism. A large database showing theoretical links between autism and genetic loci summarises research indicating that the genetic influence may extend to every human chromosome. It has been observed in one twin-study in Britain that there was about a 60% concordance rate for autism in monozygotic (identical) twins, while dizygotic (non-identical) twins and other siblings comparatively exhibited about 4% concordance rates. Some research posits that the chances that an identical twin of an autistic person will also be autistic are 85-90%. The increased probabilities of siblings having autism has been calculated at about 35-fold more than normal.

Accompanying impairments are also a common feature of autism. Some people with autism also have gastrointestinal, immunological or neurological symptoms in addition to behavioral impairments. These associated complexes have also lead to the search for specific genetic connections and helped to focus on reasonable genetic implications.

Since genes provide the information for processes and structure at the level of the cell and its components during the growth and development of a human as well as maintenance during life, gene mutations (altered versions) and deletions (complete absence of genetic material) and possibly extra copies of genes would mean that the causes of autism begin very early. If a mutated gene fails to perform properly, then cells, proteins, enzymes and other crucial aspects of normal function may be significantly altered and operate incorrectly. Deletions could mean the complete absence of a sequence of events due to missing proteins or cell components for example. These genetic alterations and deletions will simply bring about a changed structure or process which effects a great many other needed structures and processes.

Another important aspect of research in genetic factors is environmental effects and the incidence of autism. During the lifetime of a person, gene mutations and deletions may be environmentally triggered or exacerbated. Conversely, it may also be that environment will not be a factor and nothing will change the autism characteristics. For autism, the answer to these possible explanations is still being researched and there is evidence that both may be true simply because there is more than one way a person may develop autism.

Deletions and Mutations

Deleted genes have been noted as a probable influence or cause in autism. By locating specific missing genetic material the significance may be that specific genetic sites for autism controlling or causing autism (autism susceptibility alleles) may be located precisely. Another significant aspect of this research is that these deletions of genetic material indicate that autism may be established in some cases during meiosis (error-prone meiosis model) and this places the genesis of autism in some at the very beginning of life.

One very important question in this line of research is whether or not gene deletions are a cause or consequence of autism-susceptibility loci located elsewhere in the chromosomes.

Gene mutations may mean a gene does not function at all or does not function in the normal way. Since genes direct how the body grows and develops, mutations, like deletions, will effect a person at the most basic levels.

Mutation and deletion effects have been delineated in numerous research publications. .

Correlated characteristics include global developmental delay, mild to severe delay of speech, social communication disorders and cognitive abilities, autistic like behaviour, high tolerance of pain, and repetitive mannerisms (e.g. chewing or mouthing).

Gene interaction may also complicate the causes leading to multiple genetic origins of autism , In a cascade like effect, when a gene loci is altered or omitted, others are effected due to change in interaction between genes and/or their functions.

Though not present in all individuals with autism, these mutations and deletions hold potential to point the way to more the genetic components of spectrum disorders. The research also advanced basic understanding in the genetic architecture of the genome of autistic individuals and will help in focusing future research.

One practical aspect of this type of research may be the development of a test that would confirm the autism diagnosis in children exhibiting symptoms and identify families who carry genetic defects that could be inherited by their children.

Mirror neurons

A theory featuring mirror neurons states that autism may involve a dysfunction of specialized neurons in the brain that should activate when observing other people. In typically-developing people, these mirror neurons are thought to perhaps play a major part in social learning and general comprehension of the actions of others.

Sociology

Due to the complexity of autism, there are many facets of sociology that need to be considered when discussing it, such as the culture which has evolved from autistic persons connecting and communicating with one another. In addition, there are several subgroups forming within the autistic community, sometimes in strong opposition to one another.

Community and politics

Further information: Autistic community and Autism rights movement.

Curing autism is a very highly controversial and politicized issue. What some call the "autistic community" has splintered into several strands. Some seek a cure for autism - sometimes dubbed by pro-cure. Others do not desire a "cure", because they point out that autism is a way of life rather than a "disease", and as such resist it. They are sometimes dubbed anti-cure. Many more may have views between these two. Recently, with scientists learning more about autism and possibly coming closer to effective remedies, some members of the "anti-cure" movement sent a letter to the United Nations demanding to be treated as a minority group rather than a group with a mental disability or disease.

There are many resources available for autistic people. Because many autistics find it easier to communicate online than in person, a large number of these resources are online. In addition, successful autistic adults, using their own experience in developing coping strategies and/or interacting with society, are often involved at the community level with children with autism, using their own experience in developing coping strategies and/or interacting with society.

The year 2002 was declared Autism Awareness Year in the United Kingdom (see Autistic Community article).

Culture

With the recent increases in autism recognition and new approaches to educating and socializing autistics, an autistic culture has begun to develop. Similar to deaf culture, autistic culture is based on a more accepting belief that autism is a unique way of being and not a disorder to be cured. There are some commonalities which are specific to autism in general as a culture, not just "autistic culture".

It is a common misperception that autistic people do not marry; many do seek out close relationships and marry. Often, they marry another autistic, although this is not always the case. Autistic people are often attracted to other autistic people due to shared interests or obsessions, but more often than not the attraction is due to simple compatibility with personality types, the same as for non-autistics. Autistics who communicate have explained that companionship is as important to autistics as it is to anyone else.

It is also a common misperception that autistic people live away from other people, such as in a rural area rather than an urban area; many autistics do happily live in a suburb or large city. However, a metropolitan area can provide more opportunities for cultural and personal conflicts, requiring greater needs for adjustment.

In schools it is commonplace for autistics to be singled out by teachers and students as "unruly," though an autistic student may not understand why his or her actions are considered inappropriate, especially when the student has a logical explanation for his or her behavior.

The interests of autistic people and so-called "geeks" or "nerds" can often overlap as autistic people can sometimes become preoccupied with certain subjects, much like anyone else. However, in practice many autistic people have difficulty with working in groups, which impairs them even in the most 'geeky' of situations. The connection of autism with so-called geek or nerd behavior has received attention in the popular press, but is still controversial within these groups.

Speculation arises over famous people and celebrities who are now suspected, but unconfirmed, of having autism and Asperger's syndrome. They are rumored to have most symptoms of autism or autistic-spectrum disorder. Biographers, personal physicians and media journalists continually investigate these rumors, but some say that the claims are actually libellous of their character as public figures, being singled out as "odd" or "nerdy" people.

Autistic adults

Communication and social problems often cause difficulties in many areas of the autistic's life. A much smaller proportion of adult autistics marry or have children than the general population. Even when they do marry, some argue, it is more likely to end in divorce than the norm, although further research should perhaps be made. Nevertheless, as more social groups form, progressively more diagnosed adults are forming relationships with others on the spectrum.

A small proportion of autistic adults, usually those with high-functioning autism or Asperger's syndrome, are able to work successfully in mainstream jobs, although frequently far below their actual level of skills and qualification. Some have managed to gain self-employment.

Others are employed in sheltered workshops under the supervision of managers trained in working with persons with disabilities. A nurturing environment at home, at school, and later in job training and at work, helps autistic people continue to learn and to develop throughout their lives.

It is often said that the Internet, since it is almost devoid of the non-verbal cues that autistics find so hard to interact with, has given some autistic individuals an environment in which they can, and do, communicate and form online communities. The internet has also provided the option of occupations such as, teleworking and independent consulting, which, in general, do not require much human interaction offline.

Under the public law, in the United States, the public schools' responsibility for providing services ends when the autistic person is 21 years of age. The autistic person and their family are then faced with the challenge of finding living arrangements and employment to match their particular needs, as well as the programs and facilities that can provide support services to achieve these goals.

Many parents of autistic children also face financial difficulties as they must often pay for essential support and therapeutic services. Furthermore, autism is often linked to poverty because autistics who might qualify for financial assistance in one country are not eligible in another, because some nations do not recognize autism as a disability.

Terminology

When referring to someone who is diagnosed with autism, the term "autistic" is often used. Alternatively, many prefer to use the person-first terminology "person with autism" or "person who experiences autism." However, it has been noted that members of the autistic community generally prefer "autistic person" for reasons that are fairly controversial. This article uses both terminologies.

Autistic savants

The autistic savant phenomenon is sometimes seen in autistic people. Estimates of the prevalence of this phenomenon range between 1% and 10%. The term is used to describe a person who is autistic and has extreme talent in a certain area of study. Although there is a common association between savants and autism (an association made especially popular by the 1988 film Rain Man), most autistic people are not savants and savantism is not unique to autistic people, though there does seem to be some relation. Mental calculators and fast computer programming skills are the most common form. A well known example is Daniel Tammet, the subject of the documentary film The Brain Man (Kim Peek, one of the inspirations for Dustin Hoffman's character in the film Rain Man, is not autistic). Bright Splinters of the Mind by Beate Hermelin is a book that explores this issue further.

Other pervasive developmental disorders

Autism and Asperger's syndrome are just two of the five pervasive developmental disorders (PDDs). The three other pervasive developmental disorders are Rett syndrome, Childhood disintegrative disorder, and Pervasive developmental disorder not otherwise specified. Some of these are related to autism, while some of them are entirely separate conditions.