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What are Intellectual and Developmental Disabilities?

Developmental disabilities are a group of conditions due to an impairment in physical, learning, language, or behavior areas. About one in six children in the U.S. have one or more developmental disabilities or other developmental delays.

Levels of intellectual and developmental disability (I/DD) vary greatly in children. Children with I/DD might have a hard time letting others know their wants and needs, and taking care of themselves. Intellectual disability could cause a child to learn and develop more slowly than other children of the same age. It could take longer for a child with intellectual disability to learn to speak, walk, dress, or eat without help, and they could have trouble learning in school.

Intellectual disability can be caused by a problem that starts any time before a child turns 18 years old – even before birth. It can be caused by injury, disease, or a problem in the brain. For many children, the cause of their intellectual disability is not known. Some of the most common known causes of intellectual disability – like Down syndrome, fetal alcohol syndrome, fragile X syndrome, genetic conditions, birth defects, and infections – happen before birth. Others happen while a baby is being born or soon after birth. Still other causes of intellectual disability do not occur until a child is older; these might include serious head injury, stroke, or certain infections.

Specific Types 

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CDC’s National Center on Birth Defects and Developmental Disabilities has information on certain intellectual and developmental disabilities. Click on the following links to learn more:

What are some of the signs of intellectual disability?

Usually, the more severe the degree of intellectual disability, the earlier the signs can be noticed. However, it might still be hard to tell how young children will be affected later in life.


Skills such as taking a first step, smiling for the first time, and waving “bye bye” are called developmental milestones. Children reach milestones in how they play, learn, speak, act, and move (crawling, walking, etc.).

There are many signs of intellectual disability. For example, children with intellectual disability may:


  • sit up, crawl, or walk later than other children

  • learn to talk later, or have trouble speaking

  • find it hard to remember things

  • have trouble understanding social rules

  • have trouble seeing the results of their actions have trouble solving problems

What can I do if I think my child may have intellectual disability?

Talk with your child’s doctor or nurse. If you or your doctor think there could be a problem, you can take your child to see a developmental pediatrician or other specialist, and you can contact your local early intervention agency (for children under 3) or public school (for children 3 and older). 

To help your child reach his or her full potential, it is very important to get help for him or her as early as possible!

Content source: National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention

TMI is here to help in any way that we can. We offer services for individuals of all ages. Please contact us with any questions that you may have.

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