What are the early signs and symptoms of Autism Spectrum Disorder?

Autism Spectrum Disorder (or ASD for short) is characterised by a difficulty with social communication and repetitive patterns of behaviour. This article explores these two areas in more detail giving a comprehensive guide to the early signs and symptoms of ASD.

a woman kissing a young autistic child on the cheek
This blog explores techniques and ideas that come from the Positive Behaviour Support Framework which you can read more about here

Autism Spectrum Disorder (ASD) is characterised by difficulties in two domains: (1) social communication and social interaction; and (2) restricted, repetitive patterns of behaviour, interests, or activities. The first signs of ASD begin to emerge in the first year of life and can be detected between 6 months and 18 months of age. For example, you may see that the child is having difficulty with making eye contact, not babbling, not pointing, or using other gestures. not responding to his or her name and does not engage with others. 

However, some children with ASD start to develop social communication skills such as shared affected and social engagement and communication skills as expected and then regress, just before or sometime during age 2 years (Zwaigenbaum et al., 2015).  For example, the child will stop making eye contact, using language, playing with other children, and other learned social skills. Researchers have not found the link between why some children regress or which children are at risk of doing so.

Whilst the signs and symptoms appear quite early the median age of diagnosis is between 3 and 4 years (Maenner et al., 2021). Early identification and intervention are imperative. They have a strong positive effect on the developmental trajectories and quality of life of the child with ASD (Elder et al., 2017). 

Caregivers can act as the first “screeners” for autism and similar conditions by paying close attention to their infant’s social, emotional, and language development. In Table 1 below, we have outlined expected social interaction and social communication developmental milestones for children aged 0 -2 years. Table 2 outlines the behaviours that are associated with restricted, repetitive patterns of behaviour, interests, or activities. Please remember Autism is known as a “spectrum” disorder because the way the characteristics manifest and the severity of the symptoms will vary greatly from one child to another, hence referring to a "spectrum" or "continuum'.

If your child is not exhibiting the behaviours and skills listed in the table below that are fitting for his/her age, it does not mean your child has a developmental condition instead it simply means it needs to be further investigated.  It is also important to note that there is a lot of overlap of characteristics between various conditions.  

For example, a child with a Social Communication Disorder has similar difficulties with social communication and social interaction as children with ASD, however they do not have the restrictive and repetitive behaviours.  Children with Attention Deficit Hyperactivity Disorder may exhibit similarities with reduced eye contact, not responding to their name or saying socially inappropriate things caused by inattentiveness, distractibility, lack of impulse control or social skill difficulties.  Children with social anxiety or other anxiety disorders may present with some symptoms suggestive of ASD, as well.  They may have reduced eye contact, limited relational attention, be unlikely to initiate interactions and display resistance to change because they prefer familiar routines and people. These similarities in characteristics can result in some children getting an incorrect or late diagnosis.By getting the appropriate diagnosis we can understand the causes of your child's behaviour and work out how you can help. Please refer to the blog on teaching strategies for children with ASD.

Hence for a certain diagnosis of ASD, a comprehensive assessment by a multidisciplinary team of various professionals including a paediatrician, psychologist, speech pathologist and occupational therapist is useful. The professionals will base their assessment on the criteria outlined in Diagnostic and Statistical Manual of Mental Disorders (DSM-5).  This thorough investigation of a child’s symptoms will help rule out numerous conditions and accurately diagnose the condition.  This will help when providing and deciphering the best intervention that would most benefit the child.

Social communication and social interaction

Please note the following does not contain a comprehensive list of all the skills that might be found under each heading.

0-3 Months

Receptive skill

  • He/she reacts to caregiver speaking (e.g. turns head, smiles or quietens).
  • He/she reacts to loud sounds.
  • He/she calms down or smiles when spoken to and/or picked up.

Expressive skill

  • He/she makes cooing and gurgling sounds.
  • He/she cries to signal needs (e.g. hunger, pain, wet, tired uncomfortable, scared, cold or loneliness).
  • He/she uses different cries for different needs which are recognised by caregiver.

Social skills

  • He/she shows preference for primary caregiver to stranger.
  • He/she quietens in response to familiar voice and being comforted by caregivers.
  • He/she makes eye contact with adult when held close.
  • He/she shows interest in watching faces.
  • He/she smiles to show pleasure in response to social stimulation.
  • He/she shows other emotions such as interest, boredom and sadness.
  • He/she can briefly calm self (e.g. bring hands to mouth and suck on hand).
  • He/she responds positively to love, affection and touch (e.g. hugs, cuddles and massage).
  • He/she imitates adult tongue movements.

3-6 Months

Receptive skill

  • He/she watches faces with interest.
  • He/she follows moving objects and people with eyes.
  • He/she recognises familiar objects and people.
  • He/she reacts to caregiver’s voice (e.g. turn in your direction, smile or get excited).
  • He/she l listens when spoken to.
  • He/she responds to changes in tone of voice.
  • He/she pays attention to music and rhythm.
  • He/she notices toys that make sounds.
  • He/she notices other environmental sounds (e.g. microwave, blender, vacuum cleaner).

Expressive skill

  • He/she laughs, squeals and chuckles.
  • He/she makes babbling sounds by using consonant sounds (e.g. da, da, da) to get attention.
  • He/she makes gurgling sounds and blows bubbles.
  • He/she coos more in response to caregiver’s voice.
  • He/she vocalises when happy or upset.

Social skills

  • He/she cries when upset and seek comfort.
  • He/she shows excitement by laughing, waving arms and legs.
  • He/she knows differences between familiar and unfamiliar people,
  • He/she enjoys playing with people, especially caregivers.
  • He/she imitates smiles and frowns.
  • He/she smiles spontaneously (e.g. at oneself in the mirror, at people).
  • He/she pays attention to own name.
  • He/she makes different kinds of sounds to express feelings (e.g. happiness, upset).

6-9 Months

Receptive skill

  • He/she starts to respond to own name.
  • He/she watches caregiver’s mouth when they talk.
  • He/she gives attention to conversation.
  • He/she appears to understand some familiar and routine words (e.g. bed, bottle , car and no).
  • He/she looks at pictures briefly.
  • He/she follows and anticipates simple routine sequences (e.g. milk, meal preparation or bath preparation).

Expressive skill

  • He/she babbles by using an increased variety of sounds put together in two syllables (baba, papa, mama, gaga, dada).
  • He/she imitates sounds.
  • He/she expresses a range of messages such as making requests, rejecting commenting or calling to get attention (e.g. raising hands to request being picked up or shaking head for no, clapping when a favourite song is on or vocalising loudly to get parent’s attention).

Social skills

  • He/she expresses different emotions (e.g. upset with parent leaves, loss of a toy or holding onto blanket for comfort, happiness when given a favourite treat).
  • He/she enjoys games like Peek-a-boo, hide and seek and pat-a-cake.
  • He/she shows more comfort around familiar people, and becomes afraid around strangers.

9-12 Months

Receptive skill

  • He/she reacts to a person speaking especially when name is called.
  • He/she pays attention to where caregiver is looking and pointing to (e.g. following your eye gaze or pointed finger to a toy).
  • He/she understands up to 50 words for common items and people (e.g. car, juice, truck, eyes, and daddy).
  • He/she starts to respond to simple instructions like “No,” “Come here,”, “more water?”,” give to mummy”.
  • He/she listens to songs and stories repeatedly.

Expressive skill

  • He/she gestures (points) while vocalising.
  • He/she imitates sounds and actions.
  • He/she babbles by putting together many syllables and changes in tone.
  • He/she meaningfully uses and says 1 -2 single words (e.g. mama, dada, uh-oh or bed).
  • He/she request objects and actions by using gestures, vocalising, and body language.
  • He/she refuses objects and actions by using gestures, vocalising, and body language.
  • He/she makes comments by using gestures, vocalising, and body language.
  • He/she gains attention by using gestures, vocalising, and body language.

Social skills

  • He/she plays simple social games.
  • He/she shows happiness to see parents, toys, or favourite items.
  • He/she can differentiate caregivers from strangers, and gets upset when parent must leave.
  • He/she gives affection and love.
  • He/she responds by turning to look when name is called.
  • He/she imitates some actions (e.g. waving, talking on the phone or drinking from a cup) and simple hand games.
  • He/she understands the word “no”, but may not always listen.

12-18 Months

Receptive skill

  • He/she follows simple one-part instructions e.g. come here, sit down, give me cup.
  • He/she pays attention and can point to pictures and familiar characters in books.
  • He/she recognises own name.
  • He/she understands simple questions (e.g. 'Where is puppy?').
  • He/she understands familiar phrases (e.g. give teddy a cuddle).
  • He/she understands and point to familiar objects, clothes and body parts.
  • He/she understands more words than what they can say.
  • He/she looks at what is being talking about.

Expressive skill

  • He/she can say 3 to 20 words e.g. mummy, daddy, and a few familiar objects. Intelligibility of the words will vary.
  • He/she expresses no and yes.
  • He/she uses gestures with vocalisations, speech to show someone what they want.
  • He/she imitates new words.
  • He/she makes environmental noises (e.g. animal sounds, transport, and machine sounds).
  • He/she speaks in 1 to 2 words utterances.
  • He/she uses no and yes correctly.
  • He/she uses own name to refer to self.
  • He/she asks questions by raising intonation at end of phrase (e.g. 'Go park?').
  • He/she uses speech, vocalisations, gestures, or touch to gain attention.
  • He/she makes a protest by saying no, shaking head or moving away.
  • He/she makes a comment by using speech, gestures, vocalising, or facial expressions.
  • He/she requests action/assistance, by using speech, gestures, vocalising, or facial expressions.
  • He/she greets and uses social courtesies (with prompts) using speech, gestures, vocalisations, or facial expressions.
  • He/she answers simple questions (e.g. 'where’s puppy?').

Social skills

  • He/she acknowledges when others are talking by giving eye contact, vocally responding, or repeating a word said.
  • He/she may have temper tantrums especially when tired, hungry or frustrated.
  • He/she seeks comfort from caregiver when angry, upset, scared or sad.
  • He/she shows affection to familiar people.
  • He/she is interested in interacting with children and adults.
  • He/she uses eye contact with children and adults during playful interactions.
  • He/she plays next to other children.
  • He/she may initiate play by handing toys to others but expects them to be returned.
  • He/she engages in simple pretend play.
  • He/she points to or brings an object to show others something interesting,
  • He/she uses a few strategies to self soothe e.g. sucking thumb, getting favourite teddy or asking for a cuddle.
  • He/she engages in joint attention (e.g. points to ice cream and looks at caregiver).
  • He/she is beginning to show empathy (e.g. looking sad or getting upset when someone else is crying) and offering them comfort (e.g. hug, teddy or pat on head).
  • He/she is starting to social reference i.e. seeking and using information from the caregiver to know how to deal with a new or unfamiliar situation.

18-24 Months

Receptive skill

  • He/she comprehends approximately 300 words (but may not able to able to say them all).
  • He/she understands simple pronouns, action words, body parts and names of familiar objects.
  • He/she understands simple questions, yes/no questions and related two-part instructions (e.g. get your water bottle and bag).
  • He/she listens to simple stories with pictures.
  • He/she focuses on an activity for a few minutes.
  • He/she enjoys rhymes and songs.
  • He/she points to objects or pictures when they are named,

Expressive skill

  • He/she can say at least 50 words.
  • He/she can name pictures.
  • He/she puts 2 words together (e.g. go car, no tv, more juice).
  • He/she asks simple questions (e.g. 'What's this? What's that?').
  • He/she imitates sounds words.
  • He/she sings simple songs.

Social skills

  • He/she plays near or next to other children and gets excited when with other children.
  • He/she begins to enter a play group with adult assistance.
  • He/she starting to cooperate with other children when playing.
  • He/she mimics real life situations when playing,
  • He/she begins to assert independence (“No!”, “Mine!”), indicate preferences and, wants to try doing things without help.
  • He/she have temper tantrums and may use physical aggression when frustrated.

Signs of restricted, repetitive patterns of behaviour, interests or activities

  • Stereotyped or repetitive body movements (e.g. tip toe walking, hand flapping, body rocking while standing).
  • Use of objects (e.g. repeatedly spinning wheels of a car, lining up objects or opening and closing doors).
  • Speech (e.g. repeating phrases or words or making repetitive noises).
  • Moving constantly.
  • Insistence on sameness (e.g. furniture needs to stay in the same place, drinking from the same cup, wanting to wear the same t-shirt everyday).
  • Rigid routines for daily activitie  e.g. taking a specific route to childcare, having a strict bedtime routine, need to watch a particular before leaving for school in the morning)
  • Ritualised patterns of verbal messages (e.g. needing to ask people a series of question in a particular order).
  • Non-verbal behaviour (e.g. turning the light on and off three times before entering the classroom).
  • Difficulties with dealing with changes to routines (e.g. crying, screaming, and becoming aggressive if there change in teacher).
  • Environment (e.g. having a tantrum and wanting to run away when asked to eat outside instead of the dining table).
  • Difficulties with transitioning from one activity to another (e.g. going from the playground to the classroom).
  • Highly restricted and persistent preoccupation on an interest and obsession that is abnormal in intensity or focus (e.g. wanting to learn all about washing machines, bus schedules or army).
  • Under sensitivity (hypo-reactivity) or oversensitivity (hyper-reactivity) to sensory input or unusual interest in sensory aspects of the environment (e.g. apparent indifference to pain/temperature, adverse response to specific sounds or textures, touch,  excessive smelling or touching of objects, visual fascination with lights).

As you have read this information if it has raised any concerns please speak to your local doctor who can provide a referral to the relevant professional for diagnosis and treatment if appropriate. Research shows that early intervention greatly improves outcomes, so it is important to look for these symptoms when a child is as young as soon as possible.  If you would like to learn about more practical evidence based strategies to help your child with ASD achieve better communication, social, emotional, behavioural and learning outcomes please refer to the Positive Behaviour Support Strategies for Students with Autism Spectrum Disorder online course.


Elder, J. H., Kreider, C. M., Brasher, S. N., & Ansell, M. (2017). Clinical impact of early diagnosis of autism on the prognosis and parent–child relationships. Psychology Research and Behavior Management, 10, Article 283-292.

Maenner, M.J., Shaw, K.A., Bakian, A.V., Bilder, D.A., Durkin, M.S., Esler, A., Furnier, S.M., Hallas, L., Hall-Lande, J., Hudson, A., Hughes, M.M., Patrick, M., Pierce, K., Poynter, J.N., Salinas, A., Shenouda, J., Vehorn, A., Warren, Z., Constantino, J.N., DiRienzo, M., Fitzgerald, R.T., Grzybowski, A., Spivey, M.H., Pettygrove, S., Zahorodny, W., Ali, A., Andrews, J.G., Baroud, T., Gutierrez, J., Hewitt, A., Lee, L.C., Lopez, M., Mancilla, K.C., McArthur, D., Schwenk, Y.D., Washington, A., Williams, S., & Cogswell, M.E. (2021). Prevalence and Characteristics of Autism Spectrum Disorder Among Children Aged 8 Years - Autism and Developmental Disabilities Monitoring Network. MMWR Surveill Summ, Dec 3;70(11):1-16.

Zwaigenbaum, L., Bauman, M. L., Choueiri, R., Kasari, C., Carter, A., Granpeesheh, D., Mailloux, Z., Smith Roley, S., Wagner, S., Fein, D., Pierce, K., Buie, T., Davis, P.A., Newschaffer, C., Robins, D., Wetherby, A., Stone, W.L., Yirmiya, N., Estes, A., Hansen, R.L., McPartland, J.C., & Natowicz, M.R. (2015). Early intervention for children with autism spectrum disorder under 3 years of age: Recommendations for practice and research. Pediatrics, 136( Suppl 1), S60–81. 


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