Autistic spectrum disorders (ASD) are a range of related developmental disorders that begin in childhood and persist throughout adulthood.
ASD can cause a wide range of symptoms, which are grouped into three broad categories:
•Problems and difficulties with social interaction, such as a lack of understanding and awareness of other people's emotions and feelings.
•Impaired language and communication skills, such as delayed language development and an inability to start conversations or take part in them properly.
•Unusual patterns of thought and physical behaviour. This includes making repetitive physical movements, such as hand tapping or twisting. The child develops set routines of behaviour, which can upset the child if the routines are broken.
There is currently no cure for ASD, but there are a range of treatments that can improve the symptoms listed above.
Types of ASD
The term 'spectrum' is used because the symptoms of ASD can vary from child to child, and from mild to severe.
In very broad terms, there are three main types of ASD:
•Autistic disorder, sometimes known as 'classic autism'.
•Asperger syndrome.
•Pervasive Developmental Disorder – Not Otherwise Specified (PDD-NOS), which is also known as 'atypical autism'.
Autistic disorder
Children with autistic disorder usually have significant problems with language, social interaction and behaviour. Many children with autistic disorder will also have learning difficulties and below-average intelligence.
Asperger syndrome
Children with Asperger syndrome have milder symptoms that affect social interaction and behaviour. Their language development is usually unaffected, although they often have problems in certain areas of language. For example, understanding humour or figures of speech, such as 'she’s got a chip on her shoulder' or 'it's raining cats and dogs'.
Children with Asperger syndrome usually have above-average intelligence. Some children are skilled in fields requiring logic, memory and creativity, such as maths, computer science and music. (But only 1 in 200 children are exceptionally skilled, so-called 'autistic savants').
Pervasive Developmental Disorder – Not Otherwise Specified
PDD-NOS can be thought of as a 'diagnosis of exclusion'. It is used for children who share some, but not all, of the traits of autistic disorder and/or Asperger syndrome.
Most children with PDD-NOS have milder symptoms than children with autistic disorder, but they do not share the good language skills and above-average intelligence associated with Asperger syndrome.
How common are autistic spectrum disorders?
ASD are uncommon but not rare. In England it is estimated that 1 in every 100 children has an ASD.
ASD are more common in boys than girls. Boys are three to four times more likely to develop an ASD than girls.
Are rates of ASD rising?
The number of diagnosed cases of ASD has increased over the past two decades, but this does not necessarily mean that the condition is becoming more widespread.
Some experts argue that the rise in diagnosed cases may be due to health professionals getting better at diagnosing cases correctly.
In the past, many children with an ASD may have been incorrectly labelled as 'slow', 'difficult' or 'painfully shy', and not given the treatment they needed.
Some campaigners believe that the rise in cases is due to childhood vaccination programmes:
•A side effect of the MMR (mumps, measles and rubella) vaccine. This claim is often made in England.
•A side effect of a mercury-containing compound called thiomersal, which is used as a preservative in some vaccines. This claim is often made in the US.
The MMR vaccine has been investigated extensively in a number of major studies around the world, involving millions of children. Researchers have found no evidence of a link between MMR and ASD.
In 2009, one of the country's leading ASD charities, the National Autism Society, released a statement supporting the claim that there is no link between MMR and ASD.
Thiomersal has also been extensively studied. No evidence of a link to ASD has been found. Furthermore, thiomersal was removed from vaccines in the US after 1999, yet the rates of ASD have continued to rise in the US.
Outlook
The outlook for children with ASD usually depends on how severe their symptoms are and, especially, their level of intelligence.
Children with mild to moderate symptoms who have average or above-average intelligence often grow up to be independent adults with jobs, long-term relationships and children.
Children with more severe symptoms who have below-average intelligence are unlikely to be able to live as independent adults. They may need additional care and assistance for the rest of their lives. However, there is no reason why they cannot enjoy a good quality of life.
Mon Sep 20, 2010 2:28 pm by 
