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) begins in the developmental period of life. 1.48% of boys and 0.90% of girls will have an intellectual disability consisting of learning and independent living skills struggles. Psychologists can’t measure many skills in younger children with milder forms of intellectual disability. These children will be identified due to academic delays when they enter school.


But certain groups of children can be expected or known to have an intellectual developmental disorder soon after birth due to:

  • 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) due to infections such as meningitis, whooping cough, or measles. Intellectual disabilities can also result from severe head injuries, extreme malnourishment, near-drowning situations, exposure to toxins such as lead prenatally or postnatally, or abuse.
  • Unknown reasons: Two-thirds of all children have an intellectual disability due to unknown causes.

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 communicating his needs or wants, learning new information, socially interacting with others, and making and keeping friends.
  • Practical – The child will require assistance learning independent 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 completing his homework or cleaning up his toys.


If you are concerned about your child’s intelligence, some tests can determine 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 have experienced other reasons for their motor or language skills delays.


When you look at IQ tests, the average range is between 85-115, with the mean (average) being 100. Your child is at risk of 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, he will be diagnosed with IDD.

The adaptive skills are age-related skills of independence such as:

  • Self-care skills, including dressing, brushing his teeth, feeding himself, etc.
  • Communication skills consisting of the use and understanding of verbal and nonverbal language.
  • Self-direction skills include making choices, problem-solving, and planning and starting an activity.
  • Social skills, including friendship skills, understanding and obeying rules, and understanding social and emotional cues, etc.
  • Leisure skills include participating in community activities and enjoying activities independently without needing help from others.
  • Home or school living skills, which include preparing meals, cleaning up after himself, etc.
  • Functional academics such as reading, writing, and math for everyday activities.
  • Community skills such as using public transportation and community services and shopping.
  • 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 or cure for IDD. However, children with IDD can develop many skills through school-based special education services and community services, including job-related skills for many in community-based businesses and 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%), meaning they can live full lives, provided they are given the services that 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 take 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 support to get better at these activities.

If you are interested in an in-depth look at three factors of children and adolescents that can create positive or negative futures, check out my program, Developing a Calm Class.