By Dr Eóin Rickard, Principal Psychologist at Constellation Healthcare.  

When we talk about child development, you may have heard the terms intellectual disability (ID), or global developmental delay (GDD).  This article aims to clarify how these profiles differ from that of autism, and what clinicians are looking for when trying to understand a child’s development. 

What do we mean by intellectual disability and global developmental delay? 

Global Developmental Delay and Intellectual Disability are neurodevelopmental conditions which affect learning, across almost all areas of development (e.g., language, problem-solving, everyday skills, fine motor skills). One of the key features is that a child will usually need much more repetition of a task or skill to learn it and to retain their learning. They may need something explained, shown, or practised more times than would typically be expected for a child their age. 

GDD is only used as a category for children under the age of five, where the child’s developmental profile is not yet clear. It reflects a level of complexity in a child’s presentation that can take time to fully understand, and where it is required to see how a child develops over time. This can be the case where a child is autistic, which can make understanding their overall development trickier when they are younger. 

GDD is considered to be a temporary diagnosis, and it is always the case that a diagnosis of GDD should be reviewed later in childhood. It may be the case that a GDD diagnosis would be updated to a diagnosis of Intellectual Disability depending on the child’s progress. It can also be the case that a child no longer demonstrates significant needs in relation to learning, in which case an earlier GDD diagnosis would no longer apply. 

It is also important to note that Intellectual Disability can be diagnosed at any age, including for under 5s where their developmental profile is clearer at that age. 

Overlap with autism 

Autism and Intellectual Disability/GDD share some similarities, and across all three you may see: 

• delays in developmental milestones 

• emotional regulation needs 

• impacts on social communication 

• needs in relation to everyday skills 

Autism can also co-occur with Intellectual Disability/GDD, which can make it more complex to understand what is underlying a child’s profile. 

1.Developmental Milestones 

One of the most helpful ways to differentiate between autism and GDD/ID is to look at a child’s developmental milestones, and their acquisition of skills. Verbal language, gestures and other non-verbal communication, smiling, crawling, walking, toilet training, feeding, play, dressing and washing are all developmental areas to consider here.  

An autistic child may be progressing or developing well in a number of areas, while having some difficulties in others. For example, a child may be progressing well with their problem-solving, mealtimes, and dressing, but have delays or needs with their spoken language, toileting, and teeth brushing. 

This uneven pattern can sometimes reflect a lack of interest or motivation in activities, where the child is focused on their preferred activities and not is practising others. It can also relate to differences in joint attention (i.e., how a child tunes into what is being shown or taught) when a skill is being demonstrated. 

For example, an autistic child may appear to have been shown a skill multiple times but may not actually be tuning in to what you are showing them in a way that supports acquisition of that skill (e.g., they may not watch you directly). 

There can also be other factors for an autistic child, like sensitivity to certain sensory experiences. For example, with teeth brushing, the sensory experience of the brush on their teeth may be so overwhelming they have no desire to do it at all, which may make it appear that they are unable to do it. In these cases, the skill may not be developing, not because the child cannot learn it, but because the experience of the task makes engagement difficult or intolerable for them.  

With Intellectual Disability/Global Developmental Delay, delays or needs tend to be seen across many areas rather than in a few specific ones. You would expect broader delays across development and difficulty learning new skills even with consistent teaching and support. For example, where you are sure that your child is paying attention when it is being demonstrated to them, and they are making a clear effort to do it, but still require significant repetition and support to make progress. 

Sometimes, a child may become reluctant to engage with a task because it feels difficult, which can look similar to avoidance. However, the underlying reason is different – the task may simply be too challenging for them at that point in time. 

An additional consideration relates to Play, which is the primary way that young children learn. Play development for an autistic child might appear to be delayed because they are focusing on specific interests or activities. For example, the child may really love sensory play, e.g., playing with water, playing with sand or playing with Play-Doh, and they really just want to do that as much as they can. As a result, the child may not be interested in trying out different play activities and so has less opportunity to develop skills in other areas. This can lead to a child having a great level of skill in some areas (e.g., an autistic child who loves letters being more advanced with letter recognition than their peers) while appearing to be unable to demonstrate other skills. 

Contrarily, a child with an Intellectual Disability/GDD may have delays with their play development due to challenges with the complexity of the activity, for example imaginative play or activities relating to problem solving (e.g., jigsaws, formboards, pop-up toys).  

Understanding these differences often requires very careful observation over time, and can be challenging even for experienced clinicians to tease out. 

Helpful questions to consider are: 

• Has your child developed typically in some areas but is delayed in some specific ones? 
• Does your child attend or tune in when you are teaching a skill, & do they still require a lot of scaffolding & repetition if so? 
• Has anything been flagged to you by a professional during developmental check-ups? 

2.Social engagement and communication

Another important area of difference is social motivation and communication. 

Children with intellectual disabilities are often interested in engaging with others and motivated to interact and respond, but can find it difficult to keep up with complexity in play of their peers. This can become even more of a challenge as they get older, and the language and social demands expected of them increase over time. A child with an Intellectual Disability may still be expected to demonstrate relatively typical use of gestures, facial expressions, and eye contact use when they communicate. 

With autism social engagement can look different. The child may not be interested in engaging with others, preferring to play by themselves or sometimes ignore others. There may be differences in how an autistic child uses eye contact, they may use gestures rarely or may use few facial expressions. The way in which your child communicates can give an indication of their wider development. 

 Helpful questions to consider are: 

• If you noticed delays in development in this area, were they mostly in relation to verbal/spoken language or broader than that? 
• How motivated is your child to engage with others, even if they find it difficult? 

It is really important to remember that distinguishing between autism and Intellectual Disability/GDD is rarely straightforward. The same behaviour can have several potential underlying causes or reasons, and it’s always best to seek support if you have queries or concerns about your child’s development. 

About the author

Dr Eóin Rickard, is Principal Psychologist at Constellation Healthcare. Heleads on the delivery, development and governance of high-quality psychology assessment and intervention services. With a career rooted in disability services since 2005, Eoin’s path has included work as a family support worker, assistant psychologist, and later as a clinical psychologist in HSE child and adolescent disability services. Since completing his doctorate in clinical psychology in 2017, he has specialised in working with children and young people with a wide range of developmental needs, including through the Assessment of Need process.

Autism assessments at Constellation Healthcare

Constellation Healthcare offers a pathway of support that puts children and families first – helping every child to thrive.

At Constellation Healthcare, every autism assessment is tailored to your child – their comfort, needs and communication style. The aim is to ensure we build the fullest picture of who they are and what they need to thrive. You can find out more about what’s involved at What happens in an Autism Assessment? A guide for parents in Ireland. Following the assessment, you will receive a clear, comprehensive HSE‑recognised report. Our clinics are based in Dublin and Limerick.

We apply a multidisciplinary approach and use best– practice clinical diagnostic standards and tools including the Autism Diagnostic Interview–Revised (ADI‑R) and the ADOS‑2 (Autism Diagnostic Observation Schedule – Second Edition). 

Whether an autism diagnosis is clinically indicated or not, our report will give you clear, tailored recommendations for follow‑up supports that will help you and your child. (You can find out more at Understanding your Child’s Autism Assessment report, and what happens next.)

The assessment will help you understand your child better, give you clarity and enable you to support them with greater confidence.