Diagnosing autistic children

The signs of autism can be different depending on:

  • the person
  • how old they are
  • what environment they’re in
  • how tired they are
  • if they’re working hard to act like everyone else (masking)
  • how people are communicating with them or around them
  • if they have anxiety

Autism is a lifelong condition, so it can often be diagnosed in childhood. But, it may only be recognised later in life.

These are signs of autism that health professionals look for when making a diagnosis. But, because autism is a wide spectrum, every autistic person will experience autism differently.

For example, delayed speech (learning to speak later than most children) can be a sign of autism. However, many autistic children talk at the same age as a child without autism would.

Read more about the autistic spectrum

Speak to your GP practice or health visitor if:

  • you think you or your child might be autistic, and that a formal assessment is needed to understand you or your child’s needs

They can arrange for further assessment if needed.

Signs of autism in children

The signs of autism can change as children grow. Babies and toddlers show different signs of autism than older children.

The signs of autism can also change depending on the environment your child is in. Everyone behaves differently when their environment changes. For example, you’ll likely behave differently at work than you do at home. It’s the same for autistic people. This means that an autistic child may present differently in different environments. Their way of thinking and processing hasn’t changed, but the way they manage their environment has. They may also mask in some circumstances.

Read more about masking

Many signs of autism can be seen in children who are not autistic. It’s important to discuss any concerns you have with a health professional like your GP or health visitor.

Signs of autism in babies and toddlers

Signs of autism in babies and toddlers can include a number of things that affect different parts of their life and behaviour.

Talking and emotions

Autistic babies and toddlers are more likely to:

  • start talking later than most children
  • be more interested in objects or the room around them than other people – for example, they may spend a long time with a specific toy but not respond to their name being called
  • make lots of specific repetitive movements when excited or upset – these movements will be more intense than those made by babies and toddlers who do not have autism, and might be noticed by your GP or health visitor

Autistic babies and toddlers might be less likely to:

  • smile back when you smile at them
  • point to show when they want something
  • point to show you something they find interesting
  • share when they’re feeling happy – for example, they might be having fun playing, but they might not turn around and smile at you


Autistic babies and toddlers might be more likely to:

  • spend a long time setting up toys in a certain way, and set them up the same way every time
  • enjoy lining toys up in order, or watching parts of them move
  • use their toys to act out scenes from their favourite movie or TV show rather than making up pretend stories

Autistic babies and toddlers might be less likely to:

  • seem interested in playing with other children their age

Sensory (sights, smells, sounds, touch, and tastes)

Autistic babies and toddlers might be more likely to:

  • react strongly to sounds, smells, touch, tastes, or things they can see – for example, if they like the way a stuffed toy feels, they might want to spend a lot of time stroking the toy
  • become upset if given something to eat or drink that’s new to them
  • eat a limited range of foods

Signs of autism in older children

As children experience different environments, like nursery and school, the characteristics of autism can change.


Autistic children might be more likely to:

  • speak differently to most children – for example, they might use an unusual accent, talk slowly or quickly compared to others, speak in a ‘flat’ tone that doesn’t change, or use a ‘sing-song’ voice
  • use longer or more formal words than most children, even in relaxed situations
  • enjoy sharing their interests and stories, but be less likely to ask other people about their interests
  • find it difficult to identify or describe their emotions or feelings


Autistic children might:

  • find it difficult to make and keep friends
  • have 1 or 2 good friends that they spend a lot of time with
  • spend free time, like school break times, by themselves
  • find it hard to tell the difference between someone being friendly or joking, and someone trying to bully them or hurt their feelings
  • get on better with adults than other children their age
  • get on better with children who are younger or older than them
  • spend time with a group of children, but find it hard to join in with other children’s play, and so spend a lot of time on the edge of the group
  • have friends at school, but do not see them outside of school
  • relate strongly to animals, books, or important objects, but less so to other people

Different situations and routine

Autistic children might:

  • accidentally make social mistakes, for example correcting a teacher about classroom rules
  • find some social situations, like parties or busy places, overwhelming and difficult to cope with
  • be passive around other children or adults, agreeing to everything and doing everything people ask
  • tell others what to do, including while playing
  • do well in structured situations with clear roles and rules, but find social situations with no timetable or rules difficult, for example school breaks/free play
  • find changes to their routine stressful or scary, especially if the change is unexpected – for example, having a different teacher for a day or having plans change due to bad weather

Sensory (sights, smells, sounds, touch, and tastes)

Autistic children might:

  • react strongly to sounds, smells, touch, tastes, or things they can see – for example, being unable to cope with seams in their socks or the noises in supermarkets
  • find certain sounds, smells, feelings or tastes particularly calming or enjoyable – for example, coloured lights or being tucked tightly into bed
  • make repetitive movements when excited or upset – for example flapping their hands, rocking back and forth, or making the same noise repeatedly
  • have difficulty recognising bodily needs or sensations

What happens if my child is thought to be autistic?

If you’re concerned your child might be autistic it’s important to speak to your GP, health visitor or named person at school. They’ll be able to discuss your concerns and provide you with strategies for support. They can also help you access your local neurodevelopmental assessment pathway if appropriate.

A neurodevelopmental assessment will look at all areas of your child’s development. This will include both their strengths and where they might need support. The assessment will gather information from:

  • you
  • your child’s school
  • health professionals
  • your child (through an in-person assessment)

The main aim of the assessment is to help everyone understand your child’s needs better. It may also include an assessment for a specific neurodevelopmental condition like autism.

To be diagnosed with autism, a person has to have a lot of signs of autism from birth. These signs need to have had a big effect on their life.

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Source: NHS Fife - Opens in new browser window

Last updated:
25 April 2024