Taken from the National Autistic Society's Communication magazine.

The NAS 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, writes consultant psychiatrist Lorna Wing, author of The Autistic Spectrum – a guide for parents and professionals.

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.

1. Terms used for autistic 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 – 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.

2. 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. 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.

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.

3. 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 under-lying 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 syndrome – A condition in which the person has many sudden involuntary jerky movements and vocal noises they cannot control.

Dyslexia – Specific difficulty with reading.

Dyspraxia – Specific difficulty with co-ordinating movements.

Developmental co-ordination disorder – Same as dyspraxia.

Motor co-ordination disorder – 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.

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

There are a number of conditions of this kind that can be associated 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.

5. 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 labels listed under 2 – 5 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 the UK.

Lorna Wing

Consultant psychiatrist

NAS Autism Helpline: 0845 070 4004 or email: autismhelpline@nas.org.uk

The SNAP library also has a list of specialists and information on various diagnoses. Contact the SNAP Helpline on 01277 211300 or email info@snapcharity.org