Clinical review - Autistic spectrum disorders

This article discusses common presentations, core features and behaviours that may suggest a diagnosis of ASD, and evidence-based interventions.

Section 1: Epidemiology and aetiology
Section 2: Making the diagnosis
Section 3: Managing the condition
Section 4: Prognosis
Section 5: Case study
Section 6: Evidence base

Section 1: Epidemiology and aetiology

The terms `autism’ or `autism spectrum disorder’ (ASD) are used to describe a constellation of neurodevelopmental disorders present from birth or early childhood and thought to persist throughout life. Such disorders occur in individuals with intellectual disabilities as well as those with an average or above IQ. This includes Asperger syndrome and atypical autism.

ASD is classified as a pervasive developmental disorder under the International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10, under revision) and the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5). The revised DSM-5 criteria subsume Asperger syndrome.

ASD is understood to be a neurological condition with no single cause. Genetic factors are thought to play a significant role, but there is no evidence as yet for any specific genetic pathway. Despite intense speculation, there is no evidence to support a causal link with the MMR vaccine.

Available data suggests that ASD affects around one in one hundred of the population in the UK, with males outnumbering females by four to one. This is now regarded as an underestimate because diagnosis may be missed in many females and those presenting with other symptoms and psychiatric disorders that camouflage an underlying diagnosis of ASD. Attention is now focused on earlier detection and diagnosis of females.

Important! ASD affects around one in one hundred of the population in the UK.

Section 2: Making the diagnosis

The expression of ASD varies considerably and it may be difficult to diagnose, even for experienced clinicians. ASD is more likely to be diagnosed late in more able individuals and in females.

Diagnosis is made on the basis of observation of behaviour in the context of child development, culture, social interaction and developmental milestones.

These observations roughly fall into two core features; the presence of abnormal or unusual behaviours and development (positive signs) and the absence of usual behaviours or development (negative signs).

Positive signs are usually observable and may be easier to identify than negative signs which can be subtle, especially in more able individuals.

Positive signs (presence of unusual behaviour or development) might include:

  • Speech or communication delay or impairment, such as repeating phrases or literal or unusual use of language.
  • Repetitive or ritualistic behaviours, such as lining up toys or asking the same questions over and over.
  • Unusual mannerisms, such as hand flapping, finger flicking, rocking back and forth, hair twirling.
  • Insistence on sameness, for example, unusual distress at changes in an expected routine, insistence on eating the same foods, and taking the same route to school
  • Highly developed skills or precocious abilities in narrow areas. This might include eidetic or rote memory, or a fondness for facts. The person may be a gifted artist or musician or may have spectacular abilities in memorising numbers, codes and dates. It is worth noting, however, that these typically ‘autistic savant’ characteristics are much less common than is depicted in films such as Rainman.

Negative signs (the absence of usual development or behaviours) might include:

  • Lack of interest in other people, including family, coupled with a preference for objects. This might appear as aloofness.
  • Absence of imaginative or pretend play.
  • Absent or unusual eye gaze.
  • Absence of speech, delay or loss of language.
  • Absence of a social instinct leading to an inability to predict the behaviour or understand the thoughts and intentions of others, and to read between the lines of social encounters.
  • Difficulty reading non-verbal behaviours such as gesture or body language. In more able individuals this can manifest as a focus on detail or intolerance of uncertainty which can cause great stress and appear pedantic or deliberately awkward.
  • Absence of the ability to plan and organise oneself, or to follow verbal instructions.

It is important that these observations are made in the right social and cultural context, over a period of time, not just in a clinical setting.

Best practice is that formal diagnosis is made by a multidisciplinary team, which should form the basis of the programme of support for the individual and their family. NICE recommends specific instruments for diagnosis, the composition of the team and the assessment process.1

The diagnostic process is broadly divided into an interview with the parent (or someone who knows the person well) and a structured observation or interview with the child or adult. Remember that the diagnosis is a matter of clinical judgment. There are no biomarkers. Diagnostic assessment tools can guide the decision but are not definitive.

Important! Best practice is that formal diagnosis is made by a multidisciplinary team.

This lack of precision may contribute to the debate around conceptualisation of ASD as part of either natural cognitive diversity (known as neurodiversity) or specific, as yet unrecognised, biological disorders that impact on brain development and behaviour.

Co-occurring conditions

Recent estimates suggest that up to 10% of the school population has one or more neurodevelopmental disorders. While not part of a diagnosis of ASD, other conditions may co-occur and form a significant part of the clinical picture and so should be investigated and managed. These include neurodevelopmental disorders such as tics or seizures, ADHD, dyspraxia, dyslexia, sleep disorders, psychiatric disorders - particularly related to anxiety and depression - and sensory processing disorder, which is now believed to be present in a majority and is included in the revised DSM criteria. Hearing and sight problems should also be investigated and upper and lower gastrointestinal tract problems are reported.

Section 3: Managing the condition

It is accepted that recognition of the condition is a key to effective intervention and the earlier this is done the better for the child and family.


The evidence on interventions is weak. There are debates on the ethics, cost and efficacy of interventions in people with ASD, and there are many unscientific, costly and potentially hazardous treatments available. There is no evidence in support of any specific intervention although there is support for structured, individualised, communication-based approaches.

The UK charity Research Autism website has been accredited by the NHS Information Standard and describes all available interventions for ASD.

Behavioural interventions claim the highest scientific credibility and are widely used with children and adults who have ASD. There is some concern about the effects of these approaches on the mental well being of the children long term, and the strength of the claims made is not supported by follow-up studies. Individuals with ASD are widely reported not to favour behavioural interventions and these are not recommended by NICE.

Structured interventions that enhance communication or reduce anxiety through predictability can be helpful, particularly in people with ASD who show challenging behaviour. There is growing support for interventions that reduce stress and address sensory processing problems.

Vocational training has been shown to be effective if the person is allowed to play to their strengths and where adjustments are made to the social and sensory demands of the work.

There are no medications recommended for the treatment of ASD. Psychotropic medications are widely used but this is controversial and not recommended for the core features of ASD.

Investigation and treatment of co-occurring conditions or physical symptoms should be done on the same basis as it would in a neurotypical person, but adapted to take account of the characteristics and needs of the person with ASD and their family.

It is important that the narrative around ASD and possible interventions is respectful and enabling. Acceptance of the quirks and differences of people with ASD can be hugely beneficial for the patient and family.

Bear in mind that ASD is heterogenous and what suits one person may not suit another. An individualised approach involving the patient and their family or caregiver is always recommended.

Section 4: Prognosis

For ASD, outlook is probably a better term than prognosis. ASD is generally regarded as a lifelong condition. There are individuals who have been diagnosed as children and no longer meet diagnostic criteria in adulthood, but such instances are rare and unrelated to any specific treatment or programme of intervention.

The intensity of ASD symptoms varies in individuals depending on their life circumstances. Features of ASD are more pronounced at times of stress or anxiety, such as when changing schools.

Important! Features of ASD are more pronounced at times of stress or anxiety.

Taking good care of the patient’s physical and mental health is important. Reducing stress in adolescence and adulthood is associated with better outcomes, as is a higher functioning ability.

More able individuals may be able to manage their ASD through a rewarding job or empathic partner.

Unfortunately some people with ASD do not find the right help and may spend a long time receiving life limiting treatments in the form of powerful psychotropic drugs to control behaviour, or being neglected by care organisations. Social isolation, poor lifestyle and unemployment are risk factors and in adulthood many people will continue to live with family. Fear of the future is often an ongoing concern for families and people with ASD themselves.

Section 5: Case study

Donna is 21 years old and has just started at university. This is her second attempt to leave home, the first failed because she could not get on with the course she had chosen to study. She had attended the university health centre a number of times but was noted to be verbally aggressive and intolerant of the staff.

In her exams, at the end of her first year, she simply wrote that she was going to kill herself and left the exam hall. An appointment was arranged with the GP that evening. At the assessment it was noted that Donna had experienced bullying at school and had not achieved the academic success of her siblings. She struggled to make friends and her hobby was collecting sci-fi comics. When her feelings and behaviours were discussed it transpired that she had difficulties understanding the process of making and keeping an appointment, and communicating with the staff.

Donna had evidence of significant anxiety and low mood with suicidal ideation. However, it was also apparent that she had lifelong difficulties with social situations. She was referred to a specialist team for a diagnostic assessment and her anxiety and depression were addressed. After receiving a diagnosis of ASD Donna felt that it helped her to make sense of her life. The diagnosis allowed reasonable adjustments to be put in place, which enabled her to complete her degree and get a job.

Section 6: Evidence base

Clinical trials

Pellicano E, Dinsmore A, Charman T. What should autism research focus upon? Community views and priorities from the United Kingdom. Autism, 2014; 18(7):756-70.

Pilling S, Baron-Cohen S, Megnin-Viggars O et al. Recognition, referral, diagnosis, and management of adults with autism: summary of NICE guidance. BMJ 2012; 344: e4082.

Kendall T, Megnin-Viggars O, Gould N et al. Management of autism in children and young people: summary of NICE and SCIE guidance. BMJ 2013; 347: f4865.


NICE. Autism spectrum disorder in under 19s: recognition, referral and diagnosis; Clinical guideline. CG128. London, NICE, 2011

NICE. Autism: Quality standard. QS51. London, NICE 2014

NICE. Autism spectrum disorder in adults: diagnosis and management: Clinical guideline. CG142. London, NICE, 2016


Baron Cohen S. Autism and Asperger Syndrome. Oxford University Press, 2008

Autistic UK


Research Autism

Royal College of General Practitioners: Autism Spectrum Disorder: 2016

The National Autistic Society

  • Dr Carole Buckley, GP and autism champion for the RCGP.
  • Richard Mills, Research director, Research Autism London and Honorary research fellow, Centre for applied autism research, University of Bath.
  • This is an updated version of an article that was first published in November 2009.

Click here to take a test on this article and claim a certificate on MIMS Learning


  1. NICE. Autism: Quality standard. QS51. London, NICE 2014

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