Intellectual disability
Encyclopedia
Intellectual disability is a broad concept encompassing various intellectual deficits, including mental retardation
(MR), deficits too mild to properly qualify as MR, various specific conditions (such as specific learning disability), and problems acquired later in life through acquired brain injuries or neurodegenerative diseases like dementia
. Intellectual disabilities may appear at any age.
Intellectual disability is also increasingly being used as a synonym for the term mental retardation as used in standard medical references.
is a generalized disorder characterized by significantly impaired cognitive functioning and deficits in two or more adaptive behavior
s that appears before adulthood. It has historically been defined as an Intelligence Quotient
(IQ) score under 70, but the definition now includes both a component relating to mental functioning and one relating to individuals' functional skills in their environment, so IQ is not the only factor.
Although the clinical term mental retardation is a subtype of intellectual disability the latter is now preferred by most advocates in most English-speaking countries as a euphemism
for mental retardation and is replacing it in United States official documents following the passing of Rosa's Law
on October 6, 2010. Some bodies are using developmental disability
which also has an established wider meaning.
By contrast, people with cognitive impairment have, or had, normal IQ, but show confusion, forgetfulness and difficulty concentrating; cognitive impairment is typical of brain injuries, side effects from medications, and dementia
.
is a well known example of such disorders. A learning disability cannot be cured or fixed. Individuals with learning disabilities can face unique challenges that are often pervasive throughout the lifespan. Social support can be a crucial component for students with learning disabilities in the school system. With the right support and intervention, people with learning disabilities can succeed in school and be successful later in life.
(ABI) is brain damage
caused by events after birth
, rather than as part of a genetic
or congenital disorder. It usually affects cognitive
, physical, emotion
al, social or independent functioning and can result from either traumatic brain injury
or nontraumatic injury
such as stroke
, infection
or substance abuse
. Most definitions of ABI exclude neurodegenerative disorders.
People with a brain injury may have difficulty controlling, coordinating and communicating their thoughts and actions, but they retain their intellectual abilities. However, the intellectual abilities of a person with a brain injury are likely to be interfered with by the resulting thought coordination and communication difficulties, which can make it difficult for them to express themselves in a manner intelligible to others. This may give the impression of a damaged intelligence, even though such is not the case.
is the umbrella term for the progressive loss of structure or function of neurons, including death of neurons. Many neurodegenerative diseases including Parkinson’s, Alzheimer’s, and Huntington’s occur as a result of neurodegenerative processes. As research progresses, many similarities appear which relate these diseases to one another on a sub-cellular level. Discovering these similarities offers hope for therapeutic advances that could ameliorate many diseases simultaneously.
Dementia
is a serious loss of cognitive ability in a previously unimpaired person, beyond what might be expected from normal aging. Both dementia and mental retardation
are defined by neurologists as having an IQ that is two standard deviation
s 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 (mental retardation), or a condition that is acquired later (dementia).
Dementia may be static, the result of a unique global brain injury, or progressive, resulting in long-term decline due to damage or disease in the body. In the early stages of Alzheimer's disease, whose symptoms of dementia are called mild cognitive impairment
, the person typically loses 8 to 10 IQ points per year, with the result that a person of previously normal intelligence usually becomes intellectually disabled in less than five years.
Although dementia is far more common in the geriatric population, it may occur in any stage of adulthood. The overwhelming factor emerging from genetic studies of the dementias and other central nervous system neurodegenerative conditions is abnormalities of protein handling.
Mental retardation
Mental retardation is a generalized disorder appearing before adulthood, characterized by significantly impaired cognitive functioning and deficits in two or more adaptive behaviors...
(MR), deficits too mild to properly qualify as MR, various specific conditions (such as specific learning disability), and problems acquired later in life through acquired brain injuries or neurodegenerative diseases like dementia
Dementia
Dementia is a serious loss of cognitive ability in a previously unimpaired person, beyond what might be expected from normal aging...
. Intellectual disabilities may appear at any age.
Intellectual disability is also increasingly being used as a synonym for the term mental retardation as used in standard medical references.
Mental retardation
Mental retardationMental retardation
Mental retardation is a generalized disorder appearing before adulthood, characterized by significantly impaired cognitive functioning and deficits in two or more adaptive behaviors...
is a generalized disorder characterized by significantly impaired cognitive functioning and deficits in two or more adaptive behavior
Adaptive behavior
Adaptive behavior is a type of behavior that is used to adjust to another type of behavior or situation. This is often characterized by a kind of behavior that allows an individual to change an unconstructive or disruptive behavior to something more constructive. These behaviors are most often...
s that appears before adulthood. It has historically been defined as an Intelligence Quotient
Intelligence quotient
An intelligence quotient, or IQ, is a score derived from one of several different standardized tests designed to assess intelligence. When modern IQ tests are constructed, the mean score within an age group is set to 100 and the standard deviation to 15...
(IQ) score under 70, but the definition now includes both a component relating to mental functioning and one relating to individuals' functional skills in their environment, so IQ is not the only factor.
Although the clinical term mental retardation is a subtype of intellectual disability the latter is now preferred by most advocates in most English-speaking countries as a euphemism
Euphemism
A euphemism is the substitution of a mild, inoffensive, relatively uncontroversial phrase for another more frank expression that might offend or otherwise suggest something unpleasant to the audience...
for mental retardation and is replacing it in United States official documents following the passing of Rosa's Law
Rosa's Law
Rosa's Law is a United States law which replaces several instances of "mental retardation" in law with "intellectual disability." The bill was introduced as S.2781 in the United States Senate on November 17, 2009 by Barbara Mikulski...
on October 6, 2010. Some bodies are using developmental disability
Developmental disability
Developmental disability is a term used in the United States and Canada to describe lifelong disabilities attributable to mental or physical impairments, manifested prior to age 18. It is not synonymous with "developmental delay" which is often a consequence of a temporary illness or trauma during...
which also has an established wider meaning.
By contrast, people with cognitive impairment have, or had, normal IQ, but show confusion, forgetfulness and difficulty concentrating; cognitive impairment is typical of brain injuries, side effects from medications, and dementia
Dementia
Dementia is a serious loss of cognitive ability in a previously unimpaired person, beyond what might be expected from normal aging...
.
Specific learning disability
Specific learning disability is a classification including several disorders in which a person has difficulty learning in a typical manner, usually caused by an unknown factor or factors. This is not indicative of intelligence level. Rather, people with a learning disability have trouble performing specific types of skills or completing tasks if left to figure things out by themselves or if taught in conventional ways. DyslexiaDyslexia
Dyslexia is a very broad term defining a learning disability that impairs a person's fluency or comprehension accuracy in being able to read, and which can manifest itself as a difficulty with phonological awareness, phonological decoding, orthographic coding, auditory short-term memory, or rapid...
is a well known example of such disorders. A learning disability cannot be cured or fixed. Individuals with learning disabilities can face unique challenges that are often pervasive throughout the lifespan. Social support can be a crucial component for students with learning disabilities in the school system. With the right support and intervention, people with learning disabilities can succeed in school and be successful later in life.
Acquired brain injuries
An acquired brain injuryAcquired brain injury
An acquired brain injury is brain damage caused by events after birth, rather than as part of a genetic or congenital disorder such as fetal alcohol syndrome, perinatal illness or perinatal hypoxia. ABI can result in cognitive, physical, emotional, or behavioural impairments that lead to permanent...
(ABI) is brain damage
Brain damage
"Brain damage" or "brain injury" is the destruction or degeneration of brain cells. Brain injuries occur due to a wide range of internal and external factors...
caused by events after birth
Birth
Birth is the act or process of bearing or bringing forth offspring. The offspring is brought forth from the mother. The time of human birth is defined as the time at which the fetus comes out of the mother's womb into the world...
, rather than as part of a genetic
Genetic disorder
A genetic disorder is an illness caused by abnormalities in genes or chromosomes, especially a condition that is present from before birth. Most genetic disorders are quite rare and affect one person in every several thousands or millions....
or congenital disorder. It usually affects cognitive
Cognition
In science, cognition refers to mental processes. These processes include attention, remembering, producing and understanding language, solving problems, and making decisions. Cognition is studied in various disciplines such as psychology, philosophy, linguistics, and computer science...
, physical, emotion
Emotion
Emotion is a complex psychophysiological experience of an individual's state of mind as interacting with biochemical and environmental influences. In humans, emotion fundamentally involves "physiological arousal, expressive behaviors, and conscious experience." Emotion is associated with mood,...
al, social or independent functioning and can result from either traumatic brain injury
Traumatic brain injury
Traumatic brain injury , also known as intracranial injury, occurs when an external force traumatically injures the brain. TBI can be classified based on severity, mechanism , or other features...
or nontraumatic injury
Injury
-By cause:*Traumatic injury, a body wound or shock produced by sudden physical injury, as from violence or accident*Other injuries from external physical causes, such as radiation injury, burn injury or frostbite*Injury from infection...
such as stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
, infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
or substance abuse
Substance abuse
A substance-related disorder is an umbrella term used to describe several different conditions associated with several different substances .A substance related disorder is a condition in which an individual uses or abuses a...
. Most definitions of ABI exclude neurodegenerative disorders.
People with a brain injury may have difficulty controlling, coordinating and communicating their thoughts and actions, but they retain their intellectual abilities. However, the intellectual abilities of a person with a brain injury are likely to be interfered with by the resulting thought coordination and communication difficulties, which can make it difficult for them to express themselves in a manner intelligible to others. This may give the impression of a damaged intelligence, even though such is not the case.
Neurodegenerative diseases
NeurodegenerationNeurodegeneration
Neurodegeneration is the umbrella term for the progressive loss of structure or function of neurons, including death of neurons. Many neurodegenerative diseases including Parkinson’s, Alzheimer’s, and Huntington’s occur as a result of neurodegenerative processes. As research progresses, many...
is the umbrella term for the progressive loss of structure or function of neurons, including death of neurons. Many neurodegenerative diseases including Parkinson’s, Alzheimer’s, and Huntington’s occur as a result of neurodegenerative processes. As research progresses, many similarities appear which relate these diseases to one another on a sub-cellular level. Discovering these similarities offers hope for therapeutic advances that could ameliorate many diseases simultaneously.
Dementia
Dementia
Dementia is a serious loss of cognitive ability in a previously unimpaired person, beyond what might be expected from normal aging...
is a serious loss of cognitive ability in a previously unimpaired person, beyond what might be expected from normal aging. Both dementia and mental retardation
Mental retardation
Mental retardation is a generalized disorder appearing before adulthood, characterized by significantly impaired cognitive functioning and deficits in two or more adaptive behaviors...
are defined by neurologists as having an IQ that is two standard deviation
Standard deviation
Standard deviation is a widely used measure of variability or diversity used in statistics and probability theory. It shows how much variation or "dispersion" there is from the average...
s 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 (mental retardation), or a condition that is acquired later (dementia).
Dementia may be static, the result of a unique global brain injury, or progressive, resulting in long-term decline due to damage or disease in the body. In the early stages of Alzheimer's disease, whose symptoms of dementia are called mild cognitive impairment
Mild cognitive impairment
Mild cognitive impairment is a brain-function syndrome involving the onset and evolution of cognitive impairments beyond those expected based on the age and education of the individual, but which are not significant enough to interfere with their daily activities...
, the person typically loses 8 to 10 IQ points per year, with the result that a person of previously normal intelligence usually becomes intellectually disabled in less than five years.
Although dementia is far more common in the geriatric population, it may occur in any stage of adulthood. The overwhelming factor emerging from genetic studies of the dementias and other central nervous system neurodegenerative conditions is abnormalities of protein handling.