Understanding Intellectual Disabilities
Historical Development of Intellectual Disability
Historically, people with intellectual disabilities have been referred to by various terms, including “mentally-oligofrénico,” “weak-minded,” “decreased,” “delayed,” and “mentally handicapped.” Regarding individuals with physical and/or sensory disabilities, terms like “handicapped,” “crippled,” “paralyzed,” “disabled,” “destitute,” and “maimed” have been used. The World Health Organization (WHO) proposed using the term “mental subnormality” generally and “mental deficiency” for specific cases, as well as “mental delay” for socially disadvantaged individuals.
Conceptual and Explanatory Models
Several dominant models have emerged over time:
- Demonological Model: (Middle Ages) Individuals were believed to be possessed by demons. Solution: Exorcism.
- Biological Medical Model: (Greeks and Romans, 16th to mid-20th century) Individuals were seen as patients. Solution: Medical treatments and psychosurgery.
- Intrapsychic Model: (Late 19th century) Individuals were considered mentally ill. Solution: Psychological treatment.
- Model of Abnormal Behavior: (Early 20th century) Individuals were seen as having learned maladaptive behaviors. Solution: Direct instruction and functional analysis of behavior.
- Cognitive Model: (1980s) Individuals were seen as lacking cognitive strategies. Solution: Covert reinforcement, stress inoculation, and awareness techniques.
- Model Based on Quality of Life: (1990s) Individuals are considered citizens in development. Solution: Community intervention and techniques based on medical, cognitive, and behavioral norms.
WHO: International Classification of Impairments, Disabilities, and Handicaps (ICIDH)
The ICIDH classifies the consequences of disease into three levels:
- Impairment: Any loss or abnormality of psychological, physiological, or anatomical structure. This can be permanent or temporary.
- Disability: Any restriction or lack of ability (resulting from an impairment) to perform an activity in a normal manner. This represents a decrease in the individual’s operational functionality.
- Handicap: A disadvantage resulting from an impairment or disability that limits or prevents the fulfillment of a normal role. This can relate to social integration, work, physical independence, and economic self-sufficiency.
American Association on Mental Retardation (AAMR)
The AAMR, now the American Association on Intellectual and Developmental Disabilities (AAIDD), is the oldest association in its field. It has played a key role in evolving the understanding of intellectual disability, replacing the term “mental deficiency” with “mental retardation” and later with “intellectual disability.”
9th AAMR Definition (Luckasson et al., 1992)
Mental retardation refers to substantial limitations in present functioning. It is characterized by significantly below-average intellectual functioning, generally coexisting with limitations in two or more adaptive skill areas: communication, self-care, home living, social skills, community use, self-direction, health and safety, functional academic skills, leisure, and work. Mental retardation must manifest before age 18.
This definition includes three broad elements:
- Significant limitations in intellectual functioning.
- Significant limitations in adaptive behavior.
- Manifestation during the developmental period.
Health and Intellectual Disability
The WHO defines health as “a state of complete physical, mental, and social well-being.” For individuals with intellectual disabilities, physical and mental health can significantly impact their functioning. Some individuals enjoy excellent health and can fully participate in social roles, while others experience limitations.
Types of Support
- Intermittent: Episodic support needed during transitions or specific circumstances (e.g., job loss). Example: Borderline Intellectual Disabilities.
- Limited: Consistent support for a limited time (e.g., vocational training). Example: Moderate Intellectual Disability.
- Extensive: Regular, possibly daily, support in specific environments (e.g., home or work). Example: Severe Intellectual Disability.
- Pervasive: Constant, high-intensity support across multiple settings, potentially life-sustaining. Example: Profound Intellectual Disability.
Disability, Deficiency, and Causes
Disability is any restriction or lack of ability (due to an impairment) to perform an activity in a normal manner.
Deficiency is any loss or abnormality of psychological, physiological, or anatomical structure.
Causes of Disability:
- Genetics: Inherited conditions like Down syndrome and Fragile X syndrome.
- Congenital: Conditions present at birth, potentially due to factors during pregnancy (e.g., alcohol or drug exposure).
- Acquired: Conditions resulting from accidents or illnesses after birth (e.g., encephalitis, meningitis, head injuries, asphyxia).
Degrees of Intellectual Disability
- Mild: Individuals can hold simple conversations, achieve independence in personal care, and develop social and communication skills. They may experience generalized learning difficulties.
- Moderate: Individuals experience slow language development and challenges with personal care and motor skills. They can develop social relationships and participate in simple activities.
- Severe: Individuals have limited psychomotor development and communication skills. They may acquire some basic life skills but struggle with generalization. Associated medical conditions are common.
- Profound: Individuals often have limited mobility, lack sphincter control, and require constant supervision and assistance. Associated medical conditions are common.