What are the signs of Intellectual Developmental Disorder. (Intellectual Disability)?
The journey to reach the right diagnosis and support for a child with a neurodevelopmental disorder such as intellectual developmental disorder (IDD) can be a challenging and time-consuming task. This process begins with the parent or caregiver, who observes the child and overtime picks up the signs that the child may be developing in a non-typical manner. In such circumstances the caregiver is encouraged to seek a professional opinion from a paediatrician, child psychiatrist or psychologist, who can further guide the caregiver and child in their journey to appropriate support.
Controversy around using the right terminology
There are various diagnostic terms floating around in the public domain regarding IDD, making it ever so confusing to those who are unfamiliar or new to these names. The name intellectual developmental disorder was used originally by the World Health Organisation (WHO) in the International Classification of Diseases (ICD-11). On the other hand, the American Psychiatric Association in the Diagnostic and Statistical Manual of Mental Disorders (DSM) used the diagnostic term intellectual disability to refer to the same disorder (DSM-5).
To develop consistency between the classification systems the DSM-5 has endorsed the term IDD although still mostly using the term intellectual disability (DSM-5). Its latest text-revision the DMS-5-TR has transitioned to the official use of the term IDD, although acknowledging that the title intellectual disability is still very much used by lay people and professionals (DSM-5-TR). To further complicate the matter, in the United States of America (USA) IDD was known as mental retardation until Rosa’s Law was introduced in 2010 (U.S. Government Publishing Office). What is more, in the United Kingdom, IDD is commonly known as a learning disability (Public Health England, 2023) resulting in further confusion associated with these very different learning difficulties.
What is intellectual developmental disorder (IDD)?
According to the DSM-5-TR, IDD has three main diagnostic components:
- Reduced intellectual functioning (IQ of 65-75)
- Reduced capacity to meet developmental and sociocultural expectations of independent living and community participation
- The above deficits emerged in childhood
The severity of the disability can be categorised into mild, moderate, severe and profound intellectual developmental disorder, and it is decided based on the person’s level of ability to carry out day-to-day tasks and function as part of society (Criterion B), rather than IQ scores (Criterion A) (DMS-5-TR). This is simply because one’s level of functioning in society and capacity to live independently will determine the extent of external support required for day-to-day functioning (DSM-5-TR).
What are the signs of IDD?
Regarding observations associated with intellectual functioning (Criterion A), a parent should keep an eye out for the following behaviours:
- Difficulty expressing and comprehending oral language in an age-appropriate manner
- Limited general or subject specific knowledge
- Difficulty understanding math concepts
- Difficulty identifying patterns or understanding concepts
- Difficulty writing sentences or longer texts (Beal et al. 2019).
Adaptive behaviour refers to an individual’s ability to engage in social and practical skills needed to function in society. As mentioned, this is also a deficit in individuals with IDD (Criterion B). Parents should keep an eye out for the following behaviours when observing for difficulty with adaptive behaviours:
- Difficulty to distinguish truthful from exaggerated claims
- Unable to walk or ride a bike alone within 5-block radius of home
- Unable to provide their own address and postcode
- Difficulty putting things in their proper place when finished using them
- Shows no caution around hot or dangerous items
- Difficulty to wait for their turn in games and other fun activities
- Difficulty selecting correct clothes for cold or warm days
- Difficulty controlling feelings when not getting their own way
- Difficulty stating when feeling happy, sad, scared or angry
- Delays or inability in toileting and general self-care behaviours.
- Difficulty engaging in social relationships (Dekker et al. 2002).
For further clarity when observing younger children, consider the following behaviours:
- Emotional and behavioural problems – acting out
- Trouble telling time
- Having a hard time listening
- Difficulties with concentration
- Speech problems – speaking like a younger child
- Poor memory
- Destroys own things
- Don’t get along with peers
- Runs away from home
- Sense of worthlessness
- Steels outside the home (Dekker et al. 2002).
How is IDD assessed?
In order to assess for IDD, two primary assessments have to be undertaken, first an assessment of the individual’s cognitive functioning (Criterion A) and secondly, an assessment of the individual’s adaptive functioning (Criterion B). In order to address an individual’s cognitive functioning, the individual will work with a psychologist for approximately two hours to undertake one of a variety of standardized assessments of cognitive ability, for example, the Weschler intelligence tests. In the case of adaptive functioning, the parents, carers and in some cases, teachers will be provided with a standardized assessment consisting of a collection of questions associated with the individual’s adaptive behaviour. In some cases, genetic testing is also undertaken. With the information collected from these assessments, professionals will make a judgement of whether an individual’s level of functioning in these two areas is consistent with that of IDD.
If you are suspecting that your child may have intellectual developmental disorder, and you are looking for guidance and assistance to find appropriate support, feel free to book an appointment and find out how we can assist you on this difficult journey.
Co-Author: Sharyn Jones, B Psych (Hons).
Sharyn Jones is a Brisbane psychologist with 10 years of experience working with adults, adolescents, children and their parents. Using a combination of cognitive behavioural and solution focused therapies, she aims to facilitate positive changes in client’s lives so that they can achieve and obtain their desired goals.
To make an appointment with Sharyn try Online Booking. Alternatively, you can call Vision Psychology Brisbane on (07) 3088 5422 or M1 Psychology Loganholme on (07) 3067 9129.
Co-Author: Katalin Mezei, BA (Hons) Psych & Crim, G. Dip Psych, MSc Health Psych
Katalin Mezei is a Provisional Psychologist now based in Brisbane, having completed my undergraduate and Master’s training in the United Kingdom. My aim is to help people identify my clients’ core values and help them live according to them.
To make an appointment with Katalin please call Vision Psychology Brisbane on (07) 3088 5422 or M1 Psychology Loganholme on (07) 3067 9129
American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). Washington, DC: American Psychiatric Association.
American Psychiatric Association. (2022). Diagnostic and statistical manual of mental disorders (5th ed. Text revision). Washington, DC: American Psychiatric Association.
Beal, A.L., Holdnack, J.A., Saklofske, D.H. and Weiss, L.G. (2019). Practical Considerations in WISC-V Interpretation and Intervention. London, UK: Academic Press Elsevier.
Dekker, M.C., Koot, H.M., van der Ende, J., Verhulst, F.C. (2002). Emotional and behavioural problems in children and adolescents with and without intellectual disability. Journal of Child Psychology and Psychiatry. 43:8, 1087-1098.
Public Health England. (2023). Learning disability – applying All Our Health.
World Health Organisation. (2022). International Classification of Diseases 11th Revision. (11th ed.).
U.S. Government Publishing Office (2010). Public Law 111-256 – Rosa’s Law. https://www.govinfo.gov/app/details/PLAW-111publ256