Autism is classified as a neurodevelopment disorder that manifests in delays of “social interaction, language as used in social communication, or symbolic or imaginative play,” with “onset prior to age 3 years,” according to the Diagnostic and Statistical Manual of Mental Disorders. The ICD-10 also requires symptoms to “manifest before the age of three years.” Autism is often not physiologically obvious, in that outward appearance may not indicate a disorder, and diagnosis typically comes from a complete physical and neurological evaluation.

There have been large increases in diagnosed autism, for reasons that are heavily debated by researchers in psychology and related fields within the scientific community. Some believe this increase is largely due to changed diagnostic criteria and/or societal factors, while others think the reason is environmental. The United States Centers for Disease Control (CDC) estimate the prevalence of autism spectrum disorders to be between one out of every 500 to one out of every 166 births. The National Institute of Mental Health (NIMH) states the “best conservative estimate” as 1 in 1000.

Although the specific causes of autism are unknown, there is a large database of links between autism and genetic loci that span every chromosome. Further, observations and studies that autistic children have generally larger head circumferences are intriguing, but their roles in the disorder are unclear. One group of researchers claims to have found a link between autism, abnormal blood vessel function, and oxidative stress, with potential for new medical therapies should this line of evidence prove fruitful.

With early intervention, intense therapies (most notably Applied Behavioral Analysis), practice, and schooling, some children diagnosed with autism may improve on their skills to the point of neurotypical children. Some autistic children and adults are opposed to attempts to cure autism, because they see autism as part of who they are, and in some cases they perceive attempts of a cure to be intensive and unnatural.



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,” (autos). Bleuler used it to describe the schizophrenic’s seeming difficulty in connecting with other people.

However, the classification of autism 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’s 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 are also referred to as autism spectrum disorders (ASD). 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.



Individuals diagnosed with autism can vary greatly in skills and behaviors, and their sensory system is quite different 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. On the surface, individuals who have autism are physically indistinguishable from those without. Sometimes autism co-occurs with other disorders, and in those cases outward differences may be apparent. Enlarged brain size appears to accompany autism, but the effects of this are still unknown.

In assessing developmental delays, different physicians may not always arrive at the same conclusions. Much of this is due to the somewhat vague diagnostic criteria for autism, paired with an absence of objective diagnostic tests. Nevertheless, professionals within pediatrics, child psychology, behavior analysis, and child development are always looking for early indicators of autism in order to initiate treatment as early as possible for the greatest benefit.

Social Development

Typically-developing infants are social beings-early in life they gaze at people, turn toward voices, grasp at fingers, and smile. In contrast, most autistic children do not show special interest in faces and seem to have tremendous difficulty learning to engage in everyday human interaction. Even in the first few months of life, many autistic children seem indifferent to other people, lacking the eye contact and interaction with others that non-autistic children are expected to exhibit. Some infants with autism may appear very calm; they may cry less often because they do not seek parental attention or ministration. For other children with autism, infantile development progresses normally through language acquisition. Between 18 months and 2 years, however, skills previously mastered disappear, including language and social skills.

Autistic children often seem to prefer being alone and may passively accept such things as hugs and cuddling without reciprocating, or resist attention altogether. Later, they seldom seek comfort from others or respond to parents’ displays of anger or affection in a typical way. Research has suggested that although autistic children are attached to their parents, their expression of this attachment may differ from the patterns of expression used by their typical peers. That said, however, just as each typical child is different from another, autistic children differ significantly in these areas of social attachment and interaction.

According to Simon Baron-Cohen et al, many autistic children appear to lack a “theory of mind”. Theory of mind refers to representing epistemic mental states such as knowing, believing, deceiving or imagining, and tying them together “into a coherent understanding of how mental states and actions are related.” This is a behavior cited as being exclusive to human beings above the age of five and possibly, to a lesser degree, to other higher primates such as adult gorillas, chimpanzees and bonobos. Typical 5-year-olds can usually develop insights into other people’s knowledge, feelings, and intentions based on social cues (e.g., gestures and facial expressions). An autistic individual may lack these interpretation skills, leaving them unable to predict or understand other people’s actions or intentions.

Many children with autism often experience social alienation during their school-age years. As a response to this, or perhaps because their social surroundings simply do not “fit” them, many report inventing imaginary friends, worlds, or scenarios. Making friends in real life and maintaining those friendships often proves to be difficult for those with autism.

Although not universal, it is common for autistics to have difficulty regulating their behavior, resulting in crying, verbal outbursts, or self-injurious behaviors that seem inappropriate or without cause. Those who have autism generally prefer consistent routines and environments, and they may react negatively to changes in their surroundings. It is not uncommon for these individuals to exhibit aggression, increased levels of self-stimulatory behavior, self-injury, or extensive withdrawal in overwhelming situations. However, as the child matures and receives education/training, he or she can gradually learn to control such behaviors and cope with difficult changes in other ways

Sensory System

Clinicians making a proper assessment for autism would look for symptoms much like those found in Sensory Integration Dysfunction. Children will exhibit problems coping with normal sensory input. Indicators of autism include oversensitivity or under reactivity to touch, movement, sights, or sounds; physical clumsiness or carelessness; poor body awareness; a tendency to be easily distracted; impulsive physical or verbal behavior; an activity level that is unusually high or low; not unwinding or calming oneself; difficulty learning new movements; difficulty in making transitions from one situation to another; social and/or emotional problems; delays in speech, language or motor skills; specific learning difficulties/delays in academic achievement. However, it is important to remember that while most people with autism have some degree of sensory integration difficulty, not every person who has sensory problems is autistic. Some believe that sensory issues can be helped nutritionally through sensory diets or sensory snacks which are typically put together by trained occupational therapists. The diet consists of items that are thought to help keep the senses in control, with the intention of helping the individual cope better with sensory-related problems.

Autistic individuals may sometimes also develop obsessions or routines around foods, restricting what is eaten to certain colors, textures or types of food; alternatively they may obsessively avoid certain foods with similar characteristics.

One common example is autistic hearing. An autistic person may have trouble hearing certain people while other people are perceived as speaking at a higher volume. Or the autistic may be unable to filter out sounds in certain situations, such as in a large crowd of people (see cocktail party effect). However, this is perhaps a part of autism that tends to vary widely from person to person, so these examples may not apply to every autistic person. Note that such auditory difficulties fall under auditory processing disorders, and like sensory integration dysfunction, are not necessarily experienced by all people with autism or indicative of a diagnosis of autism.

Communication Difficulties

By age 3, typical children have passed predictable language learning milestones; one of the earliest is babbling. By the first birthday, a typical toddler says words or turns when he or she hears his or her name, points when he or she wants a toy, and when offered something distasteful, makes it clear that the answer is “no.” It should be noted, however, that late language development does occur in a minority of neurotypical children.

Speech development in people with autism takes different paths than the majority of neurotypical children. Some remain mute throughout their lives with varying degrees of literacy; communication in other ways-images, visual clues, sign language, and typing may be far more natural to them. Contrary to the prevailing traditional stereotype of mute people with Kanner-type autism, around one third of people diagnosed with this type of autism will develop what is often viewed as dysfunctional verbal language, relying on rote learned stored phrases, songs, jingles and advertisements. The earliest published autobiographical account of this is Donna Williams first book, “Nobody Nowhere”, (1991). Those with the autism spectrum condition of Semantic Pragmatic Disorder fall into this group.

Those who do speak sometimes use language in unusual ways, retaining features of earlier stages of language development for long periods or throughout their lives. Some speak only single words, while others repeat a mimicked phrase over and over. Some repeat what they hear, a condition called echolalia. Sing-song repetitions in particular are a calming, joyous activity that many autistic adults engage in. Many people with autism have a strong tonal sense, and can often understand at least some spoken language whilst others can understand language fluently.

Some children may exhibit only slight delays in language, or even seem to have precocious language and unusually large vocabularies, but have great difficulty in sustaining typical conversations. The “give and take” of non-autistic conversation is hard for them, although they often carry on a monologue on a favorite subject, giving no one else an opportunity to comment. When given the chance to converse with other autistics, they comfortably do so in “parallel monologue”-taking turns expressing views and information. Just as “neurotypicals” (people without autism) have trouble understanding autistic body languages, vocal tones, or phraseology, people with autism similarly have trouble with such things in people without autism. In particular, autistic language abilities tend to be highly literal; people without autism often inappropriately attribute hidden meaning to what people with autism say or expect the person with autism to sense such unstated meaning in their own words.

Some people with high-functioning autism demonstrate advanced cognitive ability, but lack the 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.

Perhaps due to their difficulties communicating with other humans, some autistics have gravitated toward working with animals. Temple Grandin’s bestselling book Animals In Translation 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. Another autistic author is Tito Mukhopadhyay, whose books include The Mind Tree.

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 years. 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 behaviours. 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 behavioural and functioning challenges.

Repetitive Behaviors

Although people with autism usually appear physically normal and have good muscle control, unusual repetitive motions, known as self-stimulation or “stimming,” may set them apart. These behaviors might be extreme and highly apparent or more subtle. Some children and older individuals spend a lot of time repeatedly flapping their arms or wiggling their toes, others suddenly freeze in position. As children, they might spend hours lining up their cars and trains in a certain way, not using them for the type of pretend play expected of a non-autistic child. If someone accidentally moves one of these toys, the child may be tremendously upset. Autistic children often need, and demand, absolute consistency in their environment. A slight change in any routine-in mealtimes, dressing, taking a bath, or going to school at a certain time and by the same route-can be extremely disturbing to them. Autistics sometimes have persistent, intense preoccupations. For example, the child might be obsessed with learning all about computers, TV programs and movie schedules or lighthouses. A small percentage of them show great interest in different languages, numbers, symbols or science topics. Repetitive behaviors can also extend into the spoken word. Preservation of a single word or phrase, or a car license number, even for a specific number of times can also become a part of the child’s daily routine.

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 a 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.


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.

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 Syndrome

In the current Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR), the most significant difference between Autistic Disorder (Kanner’s) 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.

Whilst 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 attached. The popular depiction of autism in the media has been of relatively severe cases, for example, as seen in the films Rain Man (autistic adult) and Mercury Rising (autistic child), and in turn many 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.

Autism as A Spectrum Disorder

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.


There is a broad array of autism therapies, but the efficacy of each varies dramatically from person to person. The method that is best documented to show positive results is Applied Behavior Analysis (ABA), which is a teaching system involving systematic instruction, with tasks broken into the simplest teachable steps. Progress toward development of medical and behavior modification remedies for the more debilitating effects of autism has historically been slow-moving, due to widespread disagreements over such things as the nature and causes of autistic spectrum disorders, and by a relative lack of efficacious therapies currently recognized by medical authorities.