Written by Dr Lorna Wing, consultant psychiatrist in 2011. Lorna passed away in 2014.

The National Autistic Society Autism Helpline is frequently contacted by parents who are puzzled by the diagnostic label their child has been given. Most parents are now familiar with the terms 'autism' and 'autistic spectrum disorder'. Problems arise with a range of other diagnoses where the relationship to the autistic spectrum is not clear. I will try to clarify the situation, which is indeed confusing.

Clarification is important because, whatever other condition may also be present, when a child or adult has an autistic spectrum disorder, this has a major effect in determining the needs of the person concerned. Providing the right kind of help and services is essential for the person's future progress and quality of life. The right diagnosis and the right help also makes life much easier for the person's family.

Terms used for autistic spectrum disorders

Autistic spectrum disorders

Commonly used to cover the whole range of conditions that have in common the triad of impairment of social interaction, social communication and social imagination. This triad is associated with a repetitive pattern of behaviour. The social interaction impairment is the most important part of the triad so people who have this on its own can be included in the spectrum. This is particularly relevant for people coming for a diagnosis later in childhood or adult life. They may have learned to compensate for their disabilities in communication and imagination, but the social interaction impairment is still evident even though it may be shown in subtle ways.

  • Pervasive developmental disorders: This term is used in the International Classification of Diseases, 10th edition (ICD-10) and the American Diagnostic and Statistical Manual, 4th edition (DSM-IV) to cover more or less the same range as autistic spectrum disorders.
  • Childhood autism (ICD-10): Used when the person's behaviour fits the full picture of typical autism.
  • Autistic disorder (DSM-IV): This is the same as childhood autism.
  • Atypical autism (ICD-10): Used when the person's behaviour pattern fits most but not all the criteria for typical autism.
  • Pervasive developmental disorder not otherwise specified (PDD-NOS): This is more or less the same as atypical autism.
  • Asperger syndrome (ICD-10)/Asperger disorder (DSM-IV): Briefly, this is used for more able people who have good grammatical language but use it mainly to talk about their special interests.

Read more about the difference between 'high-functioning' autism and Asperger syndrome.

Labels sometimes used for particular patterns of disabilities and/or behaviour that can be found among people with autistic spectrum disorders

Some professionals in the field have picked out particular patterns of disabilities and/or behaviour that can be seen in some people with autistic spectrum disorders, and have named them as separate syndromes.

There is disagreement as to whether these so-called syndromes can ever occur on their own without the social communication and imagination impairments that are diagnostic of an autistic spectrum disorder.

My own view, shared by many colleagues, is that they are part of the autistic spectrum, as is shown when a detailed developmental history is taken.

Non-verbal learning disorder (NVLD)

Study of the criteria for this condition shows that it covers people with the social behaviour pattern of Asperger syndrome, who also have problems with the non-verbal skills of arithmetic and some visuo-spatial skills Dr Asperger included such people in his descriptions but also included people with social problems who were very good with numbers and visuo-spatial skills.

Right hemisphere learning disorder

The same as non-verbal learning disorder. The non-verbal learning problems mentioned above are mainly located in the right hemisphere of the brain.

Semantic-pragmatic disorder

Good grammatical language but lack of ability to use language in a socially appropriate manner. This pattern is characteristic of the people Asperger described.

Pathological demand avoidance (PDA)

Briefly, avoidance of everyday tasks and manipulative, socially inappropriate, in some cases aggressive behaviour.

Developmental disorders that are not in the autistic spectrum but often occur together with an autistic spectrum disorder

These developmental disorders can occur on their own - that is, the child or adult concerned does not have the triad of impairments. However, the disorders listed below very often occur as part of the picture of an autistic spectrum disorder.

One of the commonest mistakes made by clinicians lacking experience with autistic disorders is to observe the person's clumsiness, or reading difficulty, or poor attention span and to diagnose that as the main problem. They miss the fact that underlying the obvious difficulties seen on the surface is an autistic spectrum disorder with the characteristic social impairments.

It is of the greatest importance that the autistic spectrum disorder is recognised and the appropriate help and services provided.

Attention deficit/hyperactive disorder (ADHD)

Poor attention span together with marked overactivity.

Hyperkinetic disorder

Marked overactivity without poor attention span.

Attention deficit disorder (ADD)

Poor attention span without marked overactivity.

Tourette's syndrome

A condition in which the person has many sudden involuntary, jerky movements and vocal noises they cannot control.


Specific difficulty with reading.


Specific difficulty with co-ordinating movements.

Developmental co-ordination disorder

The same as dyspraxia.

Motor coordination disorder

Again, the same as dyspraxia.

Disorder of attention, motor co-ordination and perception (DAMP)

Used when the person has a combination of these problems. The perceptual problem may, for example, be dyslexia.

Physical conditions affecting the brain that can be associated with autistic spectrum disorders

There are a number of conditions of this kind that can occur together with autistic spectrum disorders. Just a few examples are:

  • Tuberous sclerosis
  • Fragile X
  • Rett's syndrome
  • Brain damage following encephalitis.

If a child or adult has one of these conditions together with an autistic spectrum disorder, the physical condition should have appropriate treatment.

The autistic spectrum disorder requires the type of treatment, education and other services as for any autistic spectrum disorder occurring on its own.

Terms used in the International Classification System that are applied to difficult behaviour

  • Conduct disorder
  • Oppositional defiant disorder.
These labels are most unhelpful. They simply name the behaviour without any indication of the underlying cause.

It is possible for a child or adult with an autistic spectrum disorder to be given one of these diagnoses if a proper history is not taken and the proper psychological investigations are not carried out.

If this happens the needs of the child or adult concerned and their family are likely to be misjudged, with disastrous results.

Advice for parents

If parents are given one or more of the difficult behaviour labels listed above, but feel that their son or daughter has features of an autistic spectrum disorder, the first step is to discuss this with the professional who has made the diagnosis.

If this professional insists that autism, in any of its forms, is not present, the parents should ask to be referred to someone who specialises in the field of autistic spectrum disorders.

The NAS Autism Helpline is able to give information about professionals with a special interest in autistic disorders in different areas of the UK.

What's the difference between high-functioning autism and Asperger syndrome?

High-functioning autism and Asperger syndrome are both part of the autism spectrum. The main difference between the two is thought to be in language development: people with Asperger syndrome, typically, will not have had delayed language development when younger.

Signs of high-functioning autism and Asperger syndrome

Gillberg and Ehlers (1998) identify four main areas where controversy over the difference in diagnosis still exists.

Level of cognitive functioning

The view that Asperger syndrome is autism without any additional learning disability is helpful from the diagnostic point of view as it is fairly easy to make a distinction in these circumstances. However, Asperger himself said that there might be unusual circumstances where a person could present the symptoms of Asperger syndrome with additional learning disability. It is widely recognised that high-functioning autism cannot occur in someone with an IQ below 65-70.

Motor skills

In recent years the view that Asperger syndrome can only occur when there are additional difficulties with motor skills has become more prominent. Certainly Asperger himself was well aware of the prevalence of motor skill problems in the group of people he tried to describe. It seems likely that most children with Asperger syndrome experience poor co-ordination and difficulties with fine motor control. However, many children with higher functioning autism will also have difficulties in these areas.

Language development

This is the area that probably causes the greatest controversy. Both ICD-10 and DSM-IV1 state that for a diagnosis of Asperger syndrome, spoken language development must be normal. Children with high-functioning autism may have had significant language delay. However, Asperger's original descriptions of the condition stated that speech and language peculiarities are a key feature of Asperger syndrome. Often diagnoses of Asperger syndrome are made when a child is quite old and they or their parents may have difficulty remembering the details of their language development.

Age of onset

A diagnosis of high-functioning autism and one of Asperger syndrome can be made in the same individual at different stages of development. Occasionally a child has been diagnosed with high-functioning autism in early childhood and this diagnosis has been changed to Asperger syndrome when they started school. Some diagnosticians are clearly of the view that Asperger syndrome cannot be diagnosed before a child starts school. However this is largely because areas such as social skills deficits may not become apparent until a child spends a lot of time in social settings.

To summarise

  • Both people with high-functioning autism and Asperger syndrome are affected by the 'triad of impairments' common to all people with autism.
  • Both groups are likely to be of average or above average intelligence.
  • The debate as to whether we need two diagnostic terms is ongoing.
  • However, there may be features such as age of onset and motor skill deficits which differentiate the two conditions.

Although it is frustrating to be given a diagnosis which has yet to be clearly defined it is worth remembering that the fundamental presentation of the two conditions is largely the same. This means that treatments, therapies and educational approaches should also be largely similar. At the same time, all people with autism or Asperger syndrome are unique and have their own special skills and abilities. These deserve as much recognition as the areas they have difficulty in.

If you or your son or daughter has recently been given a diagnosis of either high-functioning autism or Asperger syndrome then it is worth checking what criteria the diagnostician was using.

Read about the history of the terms 'high-functioning autism' and Asperger syndrome on the next page.

The history of the term 'autism' and Asperger syndrome

The controversy over the differences between high-functioning autism and Asperger syndrome goes back a long way: here we examine some of the literature available and the reasoning behind the existence of the two separate terms.

The term 'autism' has an unusual history. It was originally coined by a psychiatrist Eugen Bleuler in 1911 to describe what he perceived as one of the key symptoms of schizophrenia, that of social withdrawal. Autism, literally meaning 'selfism', seemed to him to describe the active detachment which affected many of his patients.

Leo Kanner and Hans Asperger 

In the 1940s when Leo Kanner in America and Hans Asperger in Austria were both beginning to identify the existence of autism they separately stumbled on this term which they felt described what they were witnessing in the children they were treating.

Kanner started from the premise that these children were experiencing childhood schizophrenia. In time he became aware that they were not exhibiting all the symptoms of schizophrenia and used the phrase 'infantile autism' to describe their condition.

Asperger identified a personality disorder affecting some of the children referred to his child psychiatry clinic which he felt was described, albeit imperfectly, by the term autism. His acute identification of autism was extraordinarily ahead of its time considering he was among the first people to chart it. Unlike schizophrenic patients, children with autism do not show a disintegration of personality. They are not psychotic; instead they show a greater or lesser degree of autism.

Kanner, an American, was writing in English. His paper was published in the UK where it gained a lot of attention. The term 'infantile autism' became increasingly widely used in the 1950s and 60s, more and more children were diagnosed with the condition. In the English-speaking world the work of Hans Asperger went largely ignored. However, in Europe he continued to conduct research and have an influence over child psychiatry.

Judith Gould and Lorna Wing's research 

We don't know if Kanner was ever aware of the work of Asperger but we do know that Asperger in later years read about the work of Leo Kanner. He argued, albeit unconvincingly, that they had identified separate syndromes with a great overlap. Other academics began to argue that Asperger's and Kanner's autism were the same syndrome. Most notably Judith Gould and Lorna Wing in their ground-breaking study in Camberwell in the late 1970s came to the conclusion that autism existed on a continuum. In 1981, Lorna Wing used the phrase 'Asperger syndrome' in a research paper to describe a distinct sub-group of patients that she had been seeing. The term became much more widely used in the English-speaking world as a result. Some professionals have felt that Asperger syndrome is a more acceptable diagnosis from the point of view of parents. They argue that there is a social stigma attached to autism which is not attached to the term Asperger syndrome.

In the case of Asperger syndrome its recognition has resulted in its placement among developmental disorders in general and autistic spectrum disorders in particular. It may well be proved to have no independent existence but this does not detract from Asperger's achievement in discerning something very special in the children he described."
Uta Frith, 1998

1 ICD-10: International classification of diseases, published by the World Health Organisation; DSM-IV: Diagnostic and statistical manual of mental disorders (version IV), published by the American Psychiatric Association.