Understanding Intellectual Developmental Disorder

When your baby is born, you immediately check to be sure that he has all his fingers and toes. You ask the delivering doctor if he looks healthy. But the one thing you can’t find out right away is if he will have any problems with his intelligence.

Intellectual developmental disorder (IDD) (formerly called mental retardation) has its beginnings in the developmental period of life. 1.48% of boys and 0.90% of girls will be intellectually disabled. This disorder consists of difficulties with learning and independent living skills. Since some of these are not easily measured before school age, you may not have a definite answer until your child begins to struggle in school.

But there are certain groups of children which can be expected or known to have an intellectual developmental disorder soon after birth. This includes:

  • Genetic conditions: Down syndrome and fragile X syndrome are two common examples.
  • Pregnancy problems: The fetal brain can be damaged by maternal use of drugs or alcohol, if there is maternal nutrition, certain infections, or preeclampsia (a condition of maternal high blood pressure, protein in her urine, and fluid retention).
  • Childbirth problems:  If there are problems during birth or the baby is born prematurely, there is an increased risk of intellectual developmental disorder.
  • Illnesses or injury: Infants and children can develop intellectual disabilities (although not all are developmental in nature) due to infections such as meningitis, whooping cough, or measles. If a child experiences a severe head injury, is extremely malnourished, was in a near-drowning situation, is exposed to toxins such as lead prenatally or postnatally, or is a victim of abuse or neglect, intellectual disability can also result.  
  • Unknown reasons: Two-thirds of all children who have intellectual disability, where the cause is unknown.

When you look at your child for problems in intelligence, you will focus on three areas:

  • Conceptual – Problems passing many developmental milestones, such as rolling over, crawling, talking, etc. There are also problems found in school with keeping up with the learning. Your child would show problems with memory, learning, reasoning, and problem-solving skills.
  • Social – Your child will struggle with communication what he needs or wants, to learn new information, to know how to socially interact with others, and to make and keep friends.
  • Practical – This can again be seen with independence activities such as crawling, walking and talking, as well as learning how to feed and dress himself, do family chores, or organize tasks such as how to complete his homework or clean up his toys.


If you are concerned about your child’s intelligence, there are tests that can figure out where your child is. Most IQ tests are not reliable before ages 4-6 years. Many professionals prefer to label the child as developmentally delayed until then since early intervention services can help close the gap for some children who had experienced other reasons for their delays in motor or language skills.


When you look at IQ tests, the average range is between 85-115, with the mean (average) being 100. Your child is at risk for being labeled (IDD) if his IQ is 70 or below. To confirm that diagnosis, an assessment of his adaptive skills – daily living skills that allow him to be independent. If these are below his actual age along with a low IQ, then he will be diagnosed as having IDD.


The adaptive skills that are looked at, in relation to his age, are:

  • Self-care skills such as dressing, brushing his teeth, feeding himself, etc.
  • Communication skills where he can use and understand verbal and nonverbal language.
  • Self-direction skills such as making choices, being able to problem solve, and planning and starting an activity.
  • Social skills which include being able to make and keep friendships, understanding and being able to obey rules, and understanding social and emotional cues, etc.
  • Leisure skills which include being able to participate in community activities and enjoy activities on his own without needing help from others.
  • Home or school living skills which include preparing meals, cleaning up after himself, etc.
  • Functional academics of being able to use reading, writing, and math for everyday activities.
  • Community use of public transportation and community services and being able to shop.
  • Work which could be in a regular business or a sheltered workshop
  • Health and safety awareness so that he can protect himself and know when he has a health problem.

There is no treatment for IDD but there are skills that can be developed to the best of his potential. These services will be provided through special education services in your child’s school. They may also provide auxiliary services such as physical therapy, occupational therapy, and speech/language therapy. Once he has graduated from high school there can also be some community-based services such as supervised or shelter-based employment. Keeping your child social can be achieved through groups such as The ARC and Special Olympics.

Most children with IDD are at the mild level (85%). This means that they can live full lives, provided they are given the services which will allow them to reach their highest potential. If your child has no physical disabilities, there is no reason that he can’t participate in sports for enjoyment (and Special Olympics if he wants to be competitive), learn an instrument, or taking up art, dancing, or other expressive arts. If he has some skills or likes to put things together, he may be able to learn to do some crafts such as building items. The limitations depend on his interest, the availability of people to teach him, and the understanding of those people that he will need more time and maybe some extra supports to get better at these activities.

If you are interested in an in-depth look at 3 factors of children and adolescents that can create positive or negative futures, check out my program, Never Assume: Know Children Before Labeling Them.

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