Intellectual Disability and Global Developmental Delay

Introduction

The Questions and Answers that follow aim to provide an introduction to intellectual disability (ID) for parents and other family members. Following those, we offer links to selected resources for more information and support and a list of valuable services.
More information about many topics relevant to children with ID and many other chronic conditions and their families can be found in the left menu. Detailed information aimed at primary care doctors can be found in our the Intellectual Disability & Global Developmental Delay module.

What is intellectual disability?

Intellectual disability (ID) is a term used when a person has certain limitations in mental functioning and in skills such as communicating, self care, and social skills. These limitations will cause a child to learn and develop more slowly than a typical child. Children with intellectual disabilities may take longer to learn to speak, walk, and take care of their personal needs such as dressing or eating. They are likely to need extra help with learning in school. They will learn, but it will take them longer. There may be some things they cannot learn.

How do you get an intellectual disability?

There are many causes of intellectual disability. The most common are:
  • Genetic conditions; examples are Down syndrome, fragile X syndrome, and phenylketonuria (PKU)
  • Problems during pregnancy
  • Premature birth
  • Problems at birth
  • Health problems such as brain infections or severe systemic infection
  • Toxic exposures
  • Metabolic errors
  • Congenital hypothyroidism

What are the symptoms?

Symptoms in infants and toddlers are: delays in crawling, sitting, walking, talking, and other developmental milestones. Symptoms in young children are: learning delays, difficulties with school, and not keeping up with peers’ development.

How is it diagnosed?

To confirm intellectual disability in a child who is showing clinical signs, the child is referred to a psychologist for an IQ test, which measures intellectual functioning. The average score is 100. Children scoring below 70 are said to have an intellectual disability. Adaptive behavior (life skills) is measured by looking at what the child can do in comparison to other children of his age, including social skills, communication skills, and skills of daily living.

What the expected outcome?

Measures of intellect and adaptive behavior may predict eventual ability to live independently. For example, people with mild to moderate ID should become relatively self-sufficient with appropriate family and community support. People with severe and profound ID will need a great deal of support and do not usually live independently. Although these measures are somewhat predictive, many people with ID have accomplished much more than originally expected. For a more specific answer, ask your child’s primary care doctor.

Will anyone else in the family get an intellectual disability?

That would depend on the underlying cause your child’s intellectual disability. For example, some genetic conditions may occur in siblings, whereas causes of ID like premature birth or toxic exposures are unlikely to. Talk with your child’s primary care doctor or a genetic counselor for more information.

What is the treatment?

While there is no treatment for ID, some of the conditions causing it (e.g., metabolic errors or congenital hypothyroidism) can be treated. Much can be done to limit secondary disabilities and to help with functional abilities.

Where can I get information on how to provide for my child when I am no longer able to provide care?

Providing for a child with ID after the parents are no longer able can be tricky and families are encouraged to consult a lawyer with expertise in this area. Financial resources should not be left directly to individuals with special needs as this may disqualify them from programs such as Medicaid and SSI (see Estate Planning Trusts and Accounts). Also, see A Family Handbook on Future Planning (ARC).

How are autism and intellectual disability related?

Both autism and intellectual disability are complex conditions arising from a number of causes. Autism refers to a condition where social functioning and communication are affected in varying degrees, whereas intellectual disability refers to deficits in intellectual functioning. Although autism and ID will sometimes occur together, they can occur independently.

Does the term developmental delay mean the same thing as intellectual disability?

IQ testing may not be very accurate until a child is 4-5 years of age, so the term developmental delay is used until formal testing can be performed. Often, children with developmental delay are later diagnosed with intellectual disability and at that point are not expected to "catch up" with their peers, although this may not always be clear to families or professionals. If there are questions about how these terms are being used about your child, ask your child’s primary care doctor.

What is the life expectancy of my child with intellectual disability?

This is a difficult question to answer because there are different degrees of intellectual disability and many causes. For a more specific answer, ask your child’s primary care doctor. Children with mild or moderate ID usually have normal life expectancies while children with severe and profound ID may sometimes have associated medical conditions that could lead to a shorter life span.

Resources

Information & Support

Where can I go for more information?

For Parents and Patients

Support

The Arc
A national, community-based organization advocating for people with intellectual and developmental disabilities and their families.

Center for Parent Information and Resources
A large resource library related to children with disabilities. Locate organizations and agencies within each state that address disability-related issues.

General

Developmental Disabilities Information (ddhealthinfo.org)
Information and resources about developmental disabilities for clinicians that includes clinical practice considerations for related conditions and information about related issues (communication, dental, mental health, CAM); University of California San Diego, School of Medicine.

Intellectual Disability (MedlinePlus)
Overview of the causes, symptoms, and treatment of ID; from the National Library of Medicine and National Institutes of Health.

Developmental Disabilities (MedlinePlus)
Reliable links to information about developmental disabilities and ID; from the National Library of Medicine and National Institutes of Health.

Learn the Signs. Act Early (CDC)
Offers many tools, videos, lists, learning materials, and an app to track a child’s developmental milestones (ages 2 months to 5 years) and act if concerned about progress; Centers for Disease Control and Prevention.

EP Magazine (Exceptional Parent)
A monthly publication that provides practical advice, emotional support, and up-to-date educational information for people with disabilities.

Financing Your Child's Healthcare (Medical Home Portal)
Information, services, and resources that may help offset some of the medical costs of caring for your child with special health care needs.

A Family Handbook on Future Planning (ARC)
Helps families develop a plan that provides personal, financial, and legal protections for their children with cognitive, intellectual, or developmental disabilities after the parents either die or can no longer provide care; a publication of The Arc of the United States and the Rehabilitation Research and Training Center (RRTC) on Aging with Developmental Disabilities.

Patient Education

Intellectual Disability Fact Sheet (English & Spanish) (CDC)
One-page fact sheet for families who may be concerned that their child has intellectual disability; Centers for Disease Control and Prevention.

Tools

Care Notebook (MHP)
The care notebook helps keep track of appointments, resources, labs, medications, tests, care providers, and more. Download the complete notebook, compile in your own binder, or download separate forms; Medical Home Portal.

Forms for Education
Descriptions and links to forms that can be adapted for states and Local Education Authorities (LEAs), usually school districts, or charter schools. Topics include evaluation and service recommendations, special dietary needs, medication administration, and authorization to release information; Medical Home Portal.

Sleep History Questionnaire (PDF Document 20 KB)
A 14-day sleep tracker and 1-page questionnaire about sleep routines and behavior.

Services for Patients & Families Nationwide (NW)

For services not listed above, browse our Services categories or search our database.

* number of provider listings may vary by how states categorize services, whether providers are listed by organization or individual, how services are organized in the state, and other factors; Nationwide (NW) providers are generally limited to web-based services, provider locator services, and organizations that serve children from across the nation.

Studies

Clinical Trials in Intellectual Disabilities (clinicaltrials.gov)
Compilation of clinical trials related to Intellectual Disabilities in children; from the National Institutes of Health

Authors & Reviewers

Initial publication: March 2012; last update/revision: October 2020
Current Authors and Reviewers:
Author: Lynne M. Kerr, MD, PhD
Reviewer: Tina Persels
Funding: The Medical Home Portal thanks the 2011-2012 URLEND Medical Home Portal trainees group for their contribution to this page.
Authoring history
2015: first version: Meghan Candee, MDR
AAuthor; CAContributing Author; SASenior Author; RReviewer