Cognitive Disability: Information on Intellectual Disability
Author: Disabled World (DW)
Updated/Revised Date: 30 Dec 2025
Contents: Synopsis - Introduction - Main - Publications - Subtopics
Synopsis: Overview of cognitive disabilities including intellectual impairments, learning disabilities, and acquired conditions like dementia and traumatic brain injury.
Intellectual disabilities, also known as developmental delay or mental retardation, are a group of disorders defined by diminished cognitive and adaptive development. Affecting more males than females, they are diagnosed in between one and three percent of the population.
Introduction
What is Cognitive Disability?
Intellectual disabilities, also known as developmental delay or mental retardation, are a group of disorders defined by diminished cognitive and adaptive development. Affecting more males than females, they are diagnosed in between one and three percent of the population.
Main Content
Broadly speaking, a cognitive disability is a variety of medical conditions affecting cognitive ability. This is a broad concept encompassing various intellectual or cognitive deficits, including intellectual disability, deficits too mild to properly qualify as intellectual disability, various specific conditions (such as specific learning disability), and problems acquired later in life through acquired brain injuries or neurodegenerative diseases like dementia. These disabilities may appear at any age.
- Intellectual Functioning: Refers to a person's ability to plan, comprehend, and reason. A child's intellectual functioning can be assessed by an intelligence test. The most common intelligence test that you've probably heard of is the IQ test. Generally, a child with scores of 70 to 75 or lower is classified as having a cognitive disability.
- Adaptive Behavior: Refers to an individual's ability to apply social and practical skills in everyday life. Examples of adaptive behavior can include personal care, social problem-solving skills, dressing and eating skills, using money, and following rules.
- Mild Cognitive Disability: Accounting for around 85% of all cognitive disabilities. Kids in this category have IQ scores between 55 and 70 and are usually included in the regular classroom.
- Moderate cognitive Disability: Students with this type of disability have IQ scores between 30 and 55.
- Severe cognitive Disability: Kids with severe cognitive disabilities have IQ scores that fall under 30 and will have few communication skills, and will need direct supervision. Of all cognitive disabilities, only about 3 to 4% of children have a severe cognitive disability.
Many cognitive disabilities have a base in physiological or biological processes within the individual, such as a genetic disorder or a traumatic brain injury. Other cognitive disabilities may be based in the chemistry or structure of the person's brain. Persons with more profound cognitive disabilities often require assistance with aspects of daily living. Persons with minor learning disabilities might be able to function adequately despite their disability, maybe to the point where their disability is never diagnosed or noticed.
Dementia is a serious loss of cognitive ability in a previously unimpaired person, beyond what might be expected from normal aging. Both dementia and intellectual disability are defined by neurologists as having an IQ that is two standard deviations below median (below about 70, when 100 is the median); the difference between these two classifications for intellectual disability is whether the low IQ represents a lifelong condition (intellectual disability), or a condition that is acquired later (dementia).
Clinical Diagnosis of Cognitive Disability
Clinical diagnosis of cognitive disability can include Down syndrome, Traumatic Brain Injury (TBI), Autism, or Dementia.
Clinical diagnosis may also include less severe cognitive conditions such as Dyslexia, Attention Deficit Disorder, Dyscalculia, and other learning disabilities.
Functional Diagnosis of Cognitive Disability
Sometimes it is more useful to avoid the medical perspective of cognitive disability and view them from a functional perspective instead.
A Functional disability perspective ignores the medical and behavioral causes of cognitive disability and focuses on the abilities and challenges the person with a cognitive disability faces. Functional cognitive disabilities may involve difficulties or deficits involving problem-solving, attention, memory, math comprehension, visual comprehension, reading, linguistic, and verbal comprehension.
Types of Cognitive Disabilities
Dyslexia
Dyslexia is the most common form of language-based learning disability.
Approximately fifteen to twenty percent of the population has some form of language-based learning disability. Dyslexia is primarily a reading disability, and there is evidence suggesting that Dyslexia is a condition that is inherited. Dyslexia is a condition that is found in both females and males from all ethnic backgrounds.
Dyslexia involves difficulty in single world decoding, often reflecting an insufficient phonological processing ability. This lack of ability is many times unexpected, relating to the person's age and other cognitive and academic abilities. The person has not experienced another form of developmental disability, or sensory impairment. The person may have trouble with different forms of language, reading, and difficulty with spelling and writing as well.
Attention Deficit Hyperactivity Disorder (ADHD)
ADHD is a medical condition affecting a person's ability to focus, sit still, and pay attention. They may have difficulty in focusing on tasks or subjects, or act impulsively; they may also get into trouble. ADHD begins in childhood, but may not be diagnosed until the person reaches adolescence or even adulthood.
Persons with ADHD may have difficulty with finishing assignments from school or tasks from home, jumping from one activity to another. They may lose things; forget things like homework or something they were supposed to do. They may have difficulty with following instructions, or following through with tasks they have been assigned. The person may make careless mistakes, or have difficulty paying attention to details. Persons with ADHD may have trouble organizing activities, or tasks, and may interrupt other people. They may fidget, feel restless, or talk excessively.
Brain Injury
There are numerous causes of brain injury, including stroke, illness, Traumatic Brain Injury (TBI), brain tumors, and Meningitis, among others.
Each brain injury is unique - there is no reliable way to predict how an individual's brain will be affected by a particular injury. Once a person's brain has been injured, health care providers perform a number of different psychological and neurological tests to determine the areas of the brain that have been damaged. With some brain injuries, the damages done and the result in behaviors are barely noticeable. In other brain injuries, the damages and affects are more extensive. The extent of the injury to the person's brain determines the outcome of the person's ability to process information.
Genetic Disability
Genetic Disabilities, such as Down syndrome, Autism, and Dementia, impact people individually.
Some persons with these disabilities can function at higher levels than others. Persons with Down's syndrome, for example, may function at a high enough level to live independently, while others with the syndrome need consistent assistance with activities of daily living. The greater the severity of the cognitive disability the person experiences, the more difficult it is for the individual to comprehend.
Curated and edited by Ian C. Langtree, Founder & Editor-in-Chief, Disabled World. This section is maintained by the Disabled World editorial team.
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