Many of these disabilities have an effect onmemory, which is the ability torecall what has been learned over time. Typically memory is moved fromsensory memory toworking memory, and then finally intolong-term memory. People with cognitive disabilities typically will have trouble with one of these types of memory.[1]
Intellectual disability, also known asgeneral learning disability,[2] and previously known asmental retardation (a term now considered offensive),[3][4] is a generalized disorder characterized by significantly impaired cognitive functioning and deficits in two or moreadaptive behaviors that appears before adulthood. It has historically been defined as anIntelligence Quotient (IQ) score under 70, but the definition now includes both one component relating to mental functioning and one relating to individuals' functional skills in their environment, so IQ is not the only factor.
Intellectual disability must have appeared in the developmental period, not only as an adult. By contrast, people withcognitive impairment have, or previously had, normal IQ, but now show confusion, forgetfulness and difficulty concentrating; cognitive impairment is typical of brain injuries, side effects from medications, anddementia.
People with a brain injury may have difficulty controlling, coordinating and communicating their thoughts and actions. They may or may not retain their intellectual abilities, depending on the type and extent of the injury. 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 false impression of a damaged intelligence even in people with normal intellectual capacity.
Neurodegenerative diseases all involve the progressive loss of structure or function ofneurons, including the death of neurons. Many neurodegenerative diseases includingParkinson's,Alzheimer's, andHuntington'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 andintellectual disability are defined by neurologists as having anIQ that is twostandard 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).[5]
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 calledmild 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.[6]
Research documents the importance of providing those with intellectual disabilities alternative spaces and contexts where they feel included and can assert their own definitions of ability and what it is to be "normal."[7]
