Within the category of Neurodevelopmental Disorders suggested by the DSM-V (Diagnostic and Statistical Manual of Mental Disorders – Fifth Version), we find two subcategories that are especially popular and sometimes confusing: Intellectual Disability (ID) and Autism Spectrum Disorder (ASD) .

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As long as they belong to the same category, ADD and ID share some characteristics. For example, they originate in early childhood and have limitations in specific or global areas of adaptive behavior. That is, in both cases the person who has the diagnosis has difficulties in developing personally, socially, academically, and occupationally in the way that is expected for his or her chronological age. However, both their diagnosis and their intervention have some important differences.

In this article we will review the differences between Intellectual Disability and Autism (or, rather, the Autism Spectrum Disorder construct).

5 differences between ADD and Intellectual Disability

Intellectual Disability and ASD often coexist, that is, after making the corresponding evaluations both can be diagnosed at the same time (in this case we speak of a comorbidity between ADD and ASD). In other words, it is very common for people with ASD to also have some manifestations of Intellectual Disability, and vice versa.

However, the two are experiences that differ on some issues, which is necessary to know in order to access a timely intervention.

1. Intellectual Skills vs. Social Communication

Intellectual disability is manifested in tasks such as reasoning, problem solving, planning, abstract thinking , decision making, academic learning or learning by experience. All this is observed on a daily basis, but can also be assessed using standardised scales.

In the case of Autism Spectrum Disorder, the major diagnostic criterion is not the intellectual area, but the area of social communication and interaction ; which is manifested as follows: little social-emotional reciprocity; little willingness to share interests, emotions or affections; the presence of a qualitative alteration of communication (for example, lack of verbal or non-verbal communication, or stereotypes in language); and a difficulty in adapting behavior to the norms of different contexts.

2. Adaptive behavior

In the case of Intellectual Disability, it is notorious the difficulty to reach the level of personal independence that is expected according to the chronological age. That is, without the necessary supports, the person has some difficulty in participating in daily life tasks, for example, at school, at work, and in the community.

This does not happen because of a lack of interest, but because the person with ID may need a constant repetition of the codes and social norms in order to acquire them and act according to them.

The adaptive behavior of ASD is manifested by little interest in sharing imaginative play or by a lack of disposition towards imitative play . It is also reflected in a lack of interest in making friends (because of a lack of intention to relate to peers).

This lack of interest stems from the fact that many of the things in their immediate environment can cause them high levels of stress and anxiety , which they alleviate through patterns or interests and restrictive, repetitive or stereotyped activities.

3. Monitoring of standards

In relation to the above, the monitoring of social norms in the case of ASD may be hindered by the presence of restricted interests , which may range from simple motor stereotypes, to the insistence on maintaining things in a way that does not vary, that is, an inflexibility towards changing routines. Children with ASD often feel conflicted when their routines are changed.

On the other hand, in Intellectual Disability, following instructions or rules may be made difficult by the way logical processing, planning or experiential learning works (for example, there may be significant difficulty in recognizing risky behaviors or situations without the necessary supports).

4. The sensory experience

Something that is also important in the diagnosis of ASD is the presence of sensory hyporreactivity or hyperreactivity . For example, there may be negative responses to some sounds or textures, or behaviors of excessive fascination with smelling or touching objects, or by closely observing and fixing objects with lights or repetitive movements.

In the case of Intellectual Disability, the sensory experience does not necessarily present itself in an exacerbated manner, since it is the intellectual experience that manifests itself most strongly.

5. The evaluation

To diagnose intellectual disability, quantitative scales measuring IQ were previously used . However, the application of these tests as diagnostic criteria is ruled out by the DSM itself.

It is now recommended that intellectual skills be assessed by tests that can provide a broad view of how they function, for example, memory and attention, visuospatial perception, or logical reasoning; all of this in relation to adaptive functioning, so that the ultimate goal of the assessment is to determine the need for supports (which, according to the DSM, can be mild, moderate, severe, or profound).

When the child is too young to be assessed through standardized scales, but his or her functioning is markedly different from that expected for his or her age, clinical assessments are performed and a diagnosis of Global Developmental Delay can be determined (if before age 5).

In the case of ASD, the diagnosis occurs primarily through observation and the clinical judgment of the practitioner. In order to standardize this, several diagnostic tests have been developed that require specific professional training and can be applied from the time the child is 2 years old.

Currently very popular are, for example, the Autism Diagnostic Interview-Revised (ADI-R) or the Autism Diagnostic Observation Scale (ADOS).

Bibliographic references:

  • Documentation Centre for Studies and Competitive Examinations (2013). DSM-5: News and Diagnostic Criteria. Retrieved May 7, 2018. Available at http://www.codajic.org/sites/www.codajic.org/files/DSM%205%20%20Novedades%20y%20Criterios%20Diagnósticos.pdf.
  • Martínez, B. and Rico, D. (2014). Neurodevelopmental disorders in DSM-5. AVAP Conference. Recovered May 7, 2018. Available at http://www.avap-cv.com/images/actividades/2014_jornadas/DSM-5_Final_2.pdf.
  • WPS. (2017). (ADOS) Autism Diagnostic Observation Schedule. Retrieved May 7, 2018. Available at https://www.wpspublish.com/store/p/2647/ados-autism-diagnostic-observation-schedule.