Autism – Causes, Epidemiology, and Prevention.


Autism, or autism spectrum disorder (ASD), refers to a range of conditions characterized by challenges with social skills, repetitive behaviors, speech and nonverbal communication, as well as by unique strengths and differences. We now know that there is not one autism but many types, caused by different combinations of genetic and environmental influences. The term “spectrum” reflects the wide variation in challenges and strengths possessed by each person with autism.

Types of autism

There are four main sub-types of autism recognized within the Diagnostic and Statistical Manual of Mental Disorders.

  • Autistic Disorder, also known as autism, childhood autism, early infantile autism, Kanner’s syndrome or infantile psychosis. People with autistic disorder usually have significant language delays, social and communication challenges, and unusual behaviors and interests. Many people with autistic disorder also have intellectual disability.
  • Asperger Syndrome, also known as Asperger’s disorder or simply Asperger’s. People with Asperger syndrome usually have some milder symptoms of autistic disorder. They might have social challenges and unusual behaviors and interests.  However, they typically do not have problems with language or intellectual disability.
  • Childhood Disintegrative Disorder, also known as CDD, dementia infantalis, disintegrative psychosis or Heller’s syndrome. These children develop normally for at least two years and then lose some or most of their communication and social skills. This is an extremely rare disorder and its existence as a separate condition is a matter of debate among many mental health professionals.
  • Pervasive Developmental Disorder-Not otherwise Specified, also known as PDD (NOS) or atypical autism.

How common is Autism?

Autism statistics from the U.S. Centers for Disease Control and Prevention (CDC) released in March 2014 identify around 1 in 68 American children as on the autism spectrum – a ten-fold increase in prevalence in 40 years. Careful research shows that this increase is only partly explained by improved diagnosis and awareness. Studies also show that autism is four to five times more common among boys than girls. An estimated 1 out of 42 boys and 1 in 189 girls are diagnosed with autism in the United States.

ASD affects over 2 million individuals in the U.S. and tens of millions worldwide. Moreover, government autism statistics suggest that prevalence rates have increased 10% to 17% annually in recent years. There is no established explanation for this continuing increase, although improved diagnosis and environmental influences are two reasons often considered.

Historical background about ASDs

  • The term Autism comes from the Greek word “autos,” meaning “self”. Eugen Bleuler coined the word “autism” in 1908 among severely withdrawn schizophrenic patients.
  • In 1943 American child psychiatrist Leo Kanner studied 11 children. The children had features of difficulties in social interactions, difficulty in adapting to changes in routines, good memory, sensitivity to stimuli (especially sound), resistance and allergies to food, good intellectual potential, echolalia or propensity to repeat words of the speaker and difficulties in spontaneous activity.
  • In 1944 Hans Asperger, working separately, studied a group of children. His children also resembled Kanner’s descriptions. The children he studied, however, did not have echolalia as a linguistic problem but spoke like grownups. He also mentioned that many of the children were clumsy and different from normal children in terms of fine motor skills.
  • Next Bruno Bettelheim studied the effect of three therapy sessions with children who he called autistic. He claimed that the problem in the children was due to coldness of their mothers. He separated the children from their parents. Kanner and Bettelheim both worked towards making hypothesis that showed autistic children had frigid mothers
  • Bernard Rimland was a psychologist and parent of a child with autism. He disagreed with Bettelheim. He did not agree that the cause of his son’s autism was due to either his or his wife’s parenting skills. In 1964, Bernard Rimland published, Infantile Autism: The Syndrome and its Implications for a Neural Theory of Behavior.
  • Autism came to be better known in the 1970’s. The Erica Foundation started education and therapy for psychotic children in the beginning of the 80s. Many parents still confused autism with mental retardation and psychosis.
  • It was in 1980’s that Asperger’s work was translated to English and published and came into knowledge.
  • It was in the 1980’s that research on autism gained momentum. It was increasingly believed that parenting had no role in causation of autism and there were neurological disturbances and other genetic ailments like tuberous sclerosis, metabolic disturbances like PKU or chromosomal abnormalities like fragile X syndrome.
  • Lorna Wing, along with Christopher Gillberg at BNK (Children’s Neuro-Psychiatric Clinic) in Sweden in the 1980’s found the Wing’s triad of disturbed mutual contact, disturbed mutual communication and limited imagination. In the 1990’s they added another factor making it a square. The factor was limited planning ability.
  • Ole Ivar Lovaas studied and furthered behavioural analysis and treatment of children with autism. Lovaas achieved limited success at first with his experimental behaviour analysis. He developed it to target younger children (less than 5 years of age) and implemented treatment at home and increased the intensity (a measurement of the amount of “therapy time”) to about 40 hours weekly. Lovaas wrote Teaching Developmentally Disabled Children: The Me Book in 1981. In 2002, Lovaas wrote, Teaching Individuals with Developmental Delays: Basic Intervention Techniques.

Signs and symptoms of ASDs

People with ASDs may have problems with social, emotional, and communication skills. They might repeat certain behaviors and might not want change in their daily activities. Many people with ASDs also have different ways of learning, paying attention, or reacting to things. ASDs begin during early childhood and last throughout a person’s life.


A child or adult with an ASD might have:

  • Not play “pretend” games (pretend to “feed” a doll)
  • Not point at objects to show interest (point at an airplane flying over)
  • Not look at objects when another person points at them
  • Have trouble relating to others or not have an interest in other people at all
  • Avoid eye contact and want to be alone
  • Have trouble understanding other people’s feelings or talking about their own feelings
  • Prefer not to be held or cuddled or might cuddle only when they want to
  • Appear to be unaware when other people talk to them but respond to other sounds
  • Be very interested in people, but not know how to talk, play, or relate to them
  • Repeat or echo words or phrases said to them, or repeat words or phrases in place of normal language (echolalia)
  • Have trouble expressing their needs using typical words or motions
  • Repeat actions over and over again
  • Have trouble adapting when a routine changes
  • Have unusual reactions to the way things smell, taste, look, feel, or sound
  • Lose skills they once had (for instance, stop saying words they were using)

Causes of autism

There’s no one cause of autism. Research suggests that autism develops from a combination of genetic and non-genetic, or environmental, influences. These influences appear to increase the risk that a child will develop autism.

  • Autism’s genetic risk factors: Changes in certain genes increase the risk that a child will develop autism. If a parent carries one or more of these gene changes, they may get passed to a child (even if the parent does not have autism).
  • Autism’s environmental risk factors: certain environmental influences may further increase – or reduce – autism risk in people who are genetically predisposed to the disorder. Importantly, the increase or decrease in risk appears to be small for any one of these risk factors:
  • Advanced parent age (either parent)
  • Pregnancy and birth complications (e.g. extreme prematurity [before 26 weeks], low birth weight, multiple pregnancies [twin, triplet, etc.]).
  • Use of alcohol
  • Maternal metabolic conditions such as diabetes and obesity
  • Use of anti-seizure drugs during pregnancy
  • Untreated phenylketonuria (called PKU, an inborn metabolic disorder caused by the absence of an enzyme)
  • Rubella (German measles)

Diagnosis of autism

  • Diagnosing autism spectrum disorder (ASD) can be difficult, since there is no medical test, like a blood test, to diagnose the disorders. Doctors look at the child’s behavior and development to make a diagnosis.
  • ASD can sometimes be detected at 18 months or younger. By age 2, a diagnosis by an experienced professional can be considered very reliable. Diagnosing an ASD takes two steps:
  • Developmental Screening
  • Comprehensive Diagnostic Evaluation

Developmental Screening

Developmental screening is a short test to tell if children are learning basic skills when they should, or if they might have delays. During developmental screening the doctor might ask the parent some questions or talk and play with the child during an exam to see how she learns, speaks, behaves, and moves. A delay in any of these areas could be a sign of a problem.

All children should be screened for developmental delays and disabilities during regular well-child doctor visits at:

  • 9 months
  • 18 months
  • 24 or 30 months

Additional screening might be needed if a child is at high risk for developmental problems due to preterm birth, low birth weight or other reasons. In addition, all children should be screened specifically for ASD during regular well-child doctor visits at:

  • 18 months
  • 24 months

Other lab tests may be done under specific circumstances. These tests include:

  • Chromosomal analysis, which may be done if intellectual disability is present or there is a family history of intellectual disability. For example, fragile X syndrome, which causes a range of below-normal intelligence problems as well as autistic-like behaviors, can be identified with a chromosomal analysis.
  • An electroencephalograph (EEG), which is done if there are symptoms of seizures
  • MRI, which may be done if there are signs of differences in the structure of the brain.

Treatment of autism

Applied behavioral analysis (ABA)

This intervention works by breaking down skills like communication and cognitive skills into smaller and simpler tasks. The tasks are then taught in a highly structured way. The simple tasks over time coalesce into more complex skills that help in development.

Early start Denver model

This is yet another behavioral intervention that combines applied behavioral analysis with developmental and relationship based approaches. The child is brought into interactive social relationships, using positive emotional exchanges and joint play activities. It improves cognitive, language and adaptive behavioral skills.

Discrete Trial Training (DTT)

This is a style of teaching that uses a series of trials and efforts to teach each step of a desired behavior or response.

Pivotal Response Training (PRT)

This is intended to increase the child’s motivation to learn and monitor his or her own behaviour and begin communication.

Verbal Behavior Intervention (VBI)

VBI is a type of ABA that focuses on teaching verbal skills.

Speech and language therapy (SLT)

This therapy aims at improving communication and language skills. This can improve their ability to interact with others socially. This intervention may use visual aids, stories and toys and other aids to develop language skills.

Occupational therapy

This focuses on development and maintenance of fine motor and adaptive skills.

Stem cell therapy



Medicines are most commonly used to treat related conditions and problem behaviors, including depression, anxiety, hyperactivity, and obsessive-compulsive behaviors.

Prevention of autism

  • Although the exact cause of autism is not known in most instances, some cases are linked to chemical exposure during pregnancy. Therefore, it is essential to avoid taking any drugs during pregnancy unless the doctor specifically prescribes them.
  • It also is essential to avoid drinking alcoholic beverages of any kind during pregnancy. Being immunized against rubella (German measles) before becoming pregnant can prevent rubella-associated autism.
  • Following delivery, there are certain measures that may be helpful in preventing autism. One is early diagnosis and treatment of phenylketonuria (PKU). This is a hereditary disease that is caused by the lack of a liver enzyme required to digest the enzyme phenylalanine.
  • Similarly, early diagnosis and treatment of celiac disease may reduce the risk of a child having autism.

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  1. Occupational Therapists not only work for Fine motor & adaptive skill, but also Sensory Issues. Called “Sensory Integration Therapy”.

  2. how many times we can give him therapy

  3. As teacher how can I plan my lesson plans to teach my children that having problems with Autism? I need your help.

  4. My grandson was developing normally until 2 years when he stopped uttering some words that he had previously learnt.

    I decided to take him to a Paediatrician. Without doing tests of any sort, he went on to say the child was autistic. In addition to telling us what to do to help the child, he went to prescribe medication which he said would calm the child. In deed the child sleeps at night unlike before. Of course he can now maintain eye contact. But can we still seek tests ?

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