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Introduction to Intellectual Disabilities

Tammy Reynolds, B.A., C.E. Zupanick, Psy.D. & Mark Dombeck, Ph.D.

The term "intellectual disability" is a specific type of disability. It is caused by limited mental capacity. Limited mental capacity makes it difficult to develop important mental abilities. This includes reasoning, planning, thinking, and judgment. This limited mental capacity makes it difficult to learn new things. The ability to learn is a very important mental ability. We learn new information and skills in school. We learn from our past mistakes. We learn how to do many things by watching others. When this ability to learn is lacking, it causes many problems in everyday life.

The Diagnostic and Statistical Manual of Mental Disorders of the American Psychiatric Association (APA, 2013) lists three main criteria for intellectual disabilities:

1. Significant limitations in intellectual functioning (mental abilities);
2. Significant limitations in adaptive functioning (conceptual skills, social skills, and practical life skills);
3. The problems begin before age 18.

Although the APA's diagnostic manual is called the Diagnostic and Statistical Manual of Mental Disorders (emphasis added), intellectual disabilities are not disorders in and of themselves. Instead, there are several causes of intellectual disabilities. For example, there are many genetic causes. Brain injuries can cause an intellectual disability. Some types of medical conditions can also affect the brain's development. Because intellectual disabilities are not disorders, there are no treatments. Instead, people are provided additional supports. These supports help people to have a satisfying life despite their disability.

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What Is an Intellectual Disability?

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Resources

  • Articles

    • Introduction to Intellectual Disabilities
    • Causes of Intellectual Disabilities
    • Diagnosis of Intellectual Disabilities
      • The Diagnosis of Intellectual Disabilities
      • Psychological Tests and Intellectual Disabilities
      • Psychological Tests and Intellectual Disabilities Continued
      • Tests of Adaptive Functioning
      • Diagnostic Criteria for Intellectual Disabilities: DSM-5 Criteria
      • The American Association on Intellectual and Developmental Disabilities (AAIDD) Diagnostic Criteria for Intellectual Disability
      • Comparing the APA and the AAIDD Diagnostic Criteria for Intellectual Disability
      • Intellectual Disability and Severity Codes
      • Intellectual Disability and Other Psychiatric Disorders
    • Historical & Contemporary Perspectives of Intellectual Disabilities
      • Historical And Contemporary Perspectives on Intellectual Disabilities
      • Early Medical Explanations of Intellectual Disability
      • History of Stigmatizing Names for Intellectual Disabilities
      • History of Stigmatizing Names for Intellectual Disabilities Continued
      • Reducing the Stigma of Intellectual Disabilities: The Evolution of Modern Medical Explanations
      • Paving the Way to a Modern Conception of Intellectual Disability: Advancements in Intelligence Testing
      • Advancements in Genetic Research
      • Social and Political Controversies Associated with Intellectual Disabilities
      • Reproductive Rights for People with Intellectual Disabilities
    • Intellectual Disabilities & Supportive Rehabilitation
      • Intellectual Disabilities and Supportive Rehabilitation: Developing an Individualized Support Plan (ISP)
      • Educational Supports and Individual Educational Plans (IEPs)
      • The Choice of Educational Settings: The Pros and Cons of Mainstreaming Children With Intellectual Disabilities
      • Effective Teaching Methods for People With Intellectual Disabilities
      • Applied Behavioral Analysis (ABA) and Intellectual Disabilities
      • Physical Therapy and Sensory Skills Training
      • Individualized Support Plans: Adaptive Functioning & Life Skills
      • Social Skills Training
      • Supported Employment and Integrated Work Sites
      • Supported Housing and Community Integration
      • Therapies for Intellectual Disabilities and Outdated/Unproven Treatments
    • Support for Families of People with Intellectual Disabilities
      • Additional Support Services for People with Intellectual Disabilities and Their Families: Community Supports
      • Additional Support Services: Financial Supports
      • Additional Support Services: Family Supports
      • Additional Support Services: Advocacy and Legal Supports
    • Intellectual Disabilities Summary & Conclusion
      • Intellectual Disabilities Summary and Conclusion
    • Intellectual Disabilities Resources & References
      • Intellectual Disabilities Resources and References
      • Intellectual Disabilities Document Revision History
  • Book & Media Reviews

    • A Special Education
    • Living with Mild Cognitive Impairment
  • Videos

    • What is Intellectual Disability?
    • Let's Talk About Intellectual Disabilities: Loretta Claiborne
    • What Causes an Intellectual Disability?
    • What Is An Intellectual Disability?
    • What's disability to me? Mia's story.
    • Primary Care of Children and Young Adults with Down Syndrome
    • Dr. Tim Shriver: Intellectually Different ... Not Disabled
    • Living with Down Syndrome: Parents, Health Professionals and Personal Perspectives