Last Updated: March 2021

It’s likely those of us who have not had a connection with an individual who has an intellectual and/or developmental disability have some questions on what the term means and how it’s connected to disabilities we’re more familiar with, like Down syndrome. 

To help understand the connection, let’s start with the definitions. 

What Are Intellectual and/or Developmental Disabilities?

Intellectual and/or developmental disabilities, also called IDDs, are diagnosed conditions that affect an individual’s physical, intellectual and/or emotional development. 

Typically, IDDs are diagnosed between birth and the age of 22, and continue to affect a person throughout their lifetime. As of 2017, the Centers for Disease Control and Prevention (CDC) have reported that about 1 in 6 children aged 3-17 years were diagnosed with an IDD by a professional. People who experience an IDD may struggle with both the ability to learn and solve problems, and adaptive behaviors like everyday social skills or life skills.

The term IDD is commonly used to describe situations in which a person has either an intellectual or physical disability or both. Developmental disabilities is a broad category and many diagnoses can be presented within the category. It’s helpful to think of IDDs in terms of the parts of the body they affect. 

Nervous System

The brain and spinal cord are major organs of the nervous system. Conditions affecting the nervous system impact a person’s ability to learn and apply information, as well as speech and movement.

Sensory System

Sensory processing disorders (SPD) affect the senses – sight, hearing, touch, taste and smell. Loud noises and lots of bright lights can be scary to children and make them feel overwhelmed in some situations. 


How the body breaks down food and liquids into nutrients is a metabolic process. A common condition you may be aware of affecting metabolism is hypothyroidism. Too much or too little production of hormones and other chemicals can affect brain function and lead to an IDD.


Typically, degenerative conditions present over time by symptoms becoming worse or loss of function more apparent as a child or adult ages.

What is Down Syndrome?

Down syndrome is a relatively common genetic disorder. All people with Down syndrome have an extra portion of chromosome 21 present in all or some of their cells. This additional genetic material alters the course of development and causes the characteristics associated with Down syndrome. Individuals with Down syndrome have some degree of mild to moderate intellectual disability, characteristic facial features, and often congenital heart disease and other health issues of varying severity. 

Down syndrome affects each person diagnosed differently. Some people have mild symptoms and are fairly healthy, while others experience more difficulty learning and more severe health problems. Every case and individual is different.

How Are IDDs and Down Syndrome Connected?

It’s important to remember that intellectual and developmental disabilities can be very complex. Each person with a developmental disability will experience the effects differently, making the connection between specific disorders flexible. 

In the case of Down syndrome, we can look back at our list of body parts and functions that may be affected. Down syndrome affects the brain, movement, intelligence and learning, which means the connection between IDDs and Down syndrome is found in the nervous system. 

Most children with Down syndrome have mild to moderate cognitive impairments, or intellectual disabilities. There is no formula for who or how an individual will be affected by IDDs or Down syndrome. Both disabilities affect all ages, races and people of different economic situations. This means the differences and similarities between two people can be very distant.


Understanding the differences between intellectual and developmental disorders, and specific disorders like Down syndrome helps communities learn more about people with IDDs and connect with people they would otherwise never have interactions with. The key component of providing quality care to adults with IDDs is creating access to vocational services, and overall community engagement and integration plans. 

Organizations like Angel Guardians provide resources to those individuals and their communities to create spaces that are safe and open to everyone. Fitness, art, recreation, socialization and employment are all areas that Angel Guardians’ programs support. Remember that you are not alone in your experiences with intellectual and/or developmental disabilities or Down syndrome. Please contact Angel Guardians to engage with our local community and make lifelong personal friendships and connections to empower yourself or your loved one.
For more information on the key components that Angel Guardians provides to individuals and the challenges they may face, sign up for our monthly newsletter. We’ll notify you of new blog posts, upcoming events and all that’s new in our efforts to build engaged communities.

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