Chapter 44 Intellectual Disability
PATHOPHYSIOLOGY
Intellectual disability (the term that is gaining widespread usage in replacing the term mental retardation) is foremost amongst the developmental disabilities in terms of its prevalence. The term intellectual disability refers to significant limitations in cognitive and adaptive functioning. This is a cognitive disability manifested during childhood (before age 18 years) that is characterized by below-normal intellectual functioning (intelligence quotient [IQ] is approximately 2 standard deviations below the norm, in the range of 70 to 75 or below) with other limitations in at least two adaptive areas of functioning: speech and language, self-care skills, home living, social skills, use of community resources, self-direction, health and safety, functional academics, leisure, and work. Newer definitions of intellectual disability adopt a functional or ecologic approach rather than applying the terminology formerly used to describe levels of mental retardation, such as mild, moderate, severe, and profound. Refer to Box 44-1 and Box 44-2 for diagnostic criteria for mental retardation (currently still in use by some organizations). Many advocates promote the use of newer designations—cognitive disability, intellectual disability, and learning disability—rather than the term mental retardation.
Box 44-1 Diagnostic Criteria for Mental Retardation
1. Significantly subaverage intellectual functioning: an intelligence quotient (IQ) of approximately 70 or below on an individually administered IQ test (for infants, a clinical judgment of significantly subaverage intellectual functioning)
2. Concurrent deficits or impairments in present adaptive functioning (i.e., the person’s effectiveness in meeting the standards expected for his or her age by his or her cultural group) in at least two of the following areas: communication, self-care, home living, social and interpersonal skills, use of community resources, self-direction, functional academic skills, work, leisure, health, and safety
3. The onset is before age 18 years:
Code based on degree of severity reflecting level of intellectual impairment:
From American Psychiatric Association: Diagnostic and statistical manual of mental disorders, ed 4, text revision (DSM-IV-TR), Washington, DC, 2000, The Association.
Box 44-2 Operational Definition of Mental Retardation
Mental retardation is characterized both by a significantly below-average score on a test of mental ability or intelligence and by limitations in the ability to function in areas of daily life, such as communication, self-care, and getting along in social situations and school activities. Mental retardation is sometimes referred to as a cognitive or intellectual disability.
Children with mental retardation can and do learn new skills, but they develop more slowly than children with average intelligence and adaptive skills. There are different degrees of mental retardation, ranging from mild to profound. A person’s level of mental retardation can be defined by their intelligence quotient (IQ), or by the types and amount of support they need.
From Centers for Disease Control and Prevention: Mental Retardation, Developmental Disabilities (serial online): www.cdc.gov/ncbddd/dd/ddmr.htm. Accessed on June 10, 2007.
Causes of intellectual disability can be classified as prenatal, perinatal, and postnatal. Prenatal causes include chromosomal disorders (trisomy 21 [Down syndrome], fragile X syndrome), syndrome disorders (Duchenne’s muscular dystrophy, neurofibromatosis [type 1]), and inborn errors of metabolism (phenylketonuria [PKU]). Perinatal causes can be categorized as those related to intrauterine problems such as abruptio placentae, maternal diabetes, and premature labor, and those related to neonatal conditions, including meningitis and intracranial hemorrhage. Postnatal causes include conditions resulting from head injuries, infections, and demyelinating and degenerative disorders. Fragile X syndrome, Down syndrome, and fetal alcohol syndrome (FAS) account for one third of the cases of intellectual disability. The occurrence of associated problems such as cerebral palsy, sensory impairments, psychiatric disorders, attention deficit hyperactivity deficit (ADHD), and seizure disorders is more likely correlated with the more severe levels of intellectual disability. Diagnosis is established early in childhood. In a few instances, intellectual disability can be prevented as demonstrated with fetal alcohol syndrome by encouraging women not to injest alcohol during pregnancy. Children born with metabolic conditions such as PKU and congenital hypothyroidism can be medically treated to prevent the consequences of nontreatment resulting in intellectual disability. Long-term prognosis is determined ultimately by the extent to which the individual can function independently in the community (i.e., employment, independent living, social skills).
INCIDENCE
1. More than 85% of persons with intellectual disability have an IQ that classifies them in the mild level (IQ between 50 and 70).
2. Prevalence rate is 1% for children between the ages of 3 years to 10 years.
3. More than 600,000 children and youth ages 6 to 21 years are estimated to have intellectual disability.
4. One of every 10 children in special education has some variation of intellectual disability.
5. Intellectual disability is more common in older children (6 to 10 years) than in younger children (3 to 5 years).
6. Male/female ratio is 1.5:1. Incidence is higher in lower socioeconomic groups.
7. Prevalence rate is higher in African Americans than in whites.
8. Risk of recurrence in families is as follows:
9. Nearly 18% of infants with very low birth weight have severe disabilities.
10. Approximately 500,000 youths have an intellectual disability.
11. The high school dropout rate for students with disabilities is 25% to 30%.
12. The unemployment rate for persons with intellectual disabilities is estimated to be between 66% and 75%.
13. Lifetime costs for all individuals born with an intellectual disability in 2000 are anticipated to reach $51.2 billion, amounting to more than $1 million per person.
CLINICAL MANIFESTATIONS
COMPLICATIONS
3. Behavioral and/or psychiatric problems
5. Constipation (caused by decreased intestinal motility secondary to anticonvulsant medications, insufficient intake of fiber and fluids)
6. Associated congenital anomalies such as esophageal malformation, small bowel obstruction, and cardiac defects
LABORATORY AND DIAGNOSTIC TESTS
1. Cognitive and developmental assessment tests, including the following:
2. Measurements of adaptive behaviors
Table 44-1 Hypotheses and Strategies for Assessing Etiologic Risk Factors
| Hypothesis | Possible Evaluation Strategies |
|---|---|
| Prenatal Onset | |
| Chromosomal disorder | Extended physical examination |
| Referral to clinical geneticist | |
| Chromosomal and DNA analysis | |
| Syndrome disorder | Extended family history and examination of relatives |
| Extended physical examination | |
| Referral to clinical geneticist | |
| Inborn error of metabolism | Newborn screening using tandem mass spectrometry |
| Analysis of amino acids in blood, urine, and/or cerebrospinal fluid | |
| Analysis of organic acids in urine | |
| Measurement of blood levels of lactate, pyruvate, very long chain fatty acids, free and total carnitine, and acylcarnitines | |
| Measurement of arterial ammonia and gases | |
| Assays of specific enzymes in cultured skin fibroblasts | |
| Biopsies of specific tissue for light and electron microscopy and biochemical analysis | |
| Cerebral dysgenesis | Neuroimaging (computed tomography or magnetic resonance imaging) |
| Social, behavioral, and environmental risk factors | Intrauterine and postnatal growth assessment |
| Placental pathologic analysis | |
| Detailed social history of parents | |
| Medical history and examination of mother | |
| Toxicologic screening of mother at prenatal visits and of child at birth | |
| Referral to clinical geneticist | |
| Perinatal Onset | |
| Intrapartum and neonatal disorders | Review of maternal records (prenatal care, labor, and delivery) |
| Review of birth and neonatal records | |
| Postnatal Onset | |
| Head injury | Detailed medical history |
| Skull radiography and neuroimaging | |
| Brain infection | Detailed medical history |
| Cerebrospinal fluid analysis | |
| Demyelinating disorders | Neuroimaging |
| Cerebrospinal fluid analysis | |
| Degenerative disorders | Neuroimaging |
| Specific DNA studies for genetic disorders | |
| Assays of specific enzymes in blood or cultured skin fibroblasts | |
| Biopsies of specific tissue for light and electron microscopy and biochemical analysis | |
| Referral to clinical geneticist or neurologist | |
| Seizure disorders | Electroencephalography |
| Referral to clinical neurologist | |
| Toxic-metabolic disorders | See “Inborn error of metabolism” in Prenatal Onset category of table |
| Toxicologic studies | |
| Lead and heavy metal assays | |
| Malnutrition | Body measurements |
| Detailed nutritional history | |
| Environmental and social disadvantage | Detailed social history |
| History of abuse or neglect | |
| Psychologic evaluation | |
| Observation in new environment | |
| Educational inadequacy | Early referral and intervention records |
| Review of educational records |
From American Association on Mental Retardation: Mental retardation: definition, classification, and systems of supports, ed 10, Washington, DC, 2002, The Association.
MEDICAL MANAGEMENT
Medical management will be highly dependent on the health care needs of the child or youth and the specific diagnosis associated with the child or youth’s intellectual disability. The goal of medical care is to promote the child’s or youth’s optimal health status and prevent complications and secondary conditions by providing primary and specialty health care. Another important goal of care is to ensure that the child or youth and primary caretakers receive the instruction needed for the development of self-care skills to manage health, personal, and disability needs on a daily and long-term basis. As the section on complications and secondary conditions demonstrates, the child or youth may have a number of secondary conditions and diagnoses that significantly affect their overall health status, such as seizure disorders, cardiac problems, and psychiatric problems. Given the array of health needs, some of the following medications may be prescribed for a child or youth with intellectual disability:
a. Psychotropic medications (e.g., thioridazine [Mellaril], haloperidol [Haldol]) for youth with self-injurious behaviors
b. Psychostimulants for youth who demonstrate attention-deficit/hyperactivity disorder (e.g., methylphenidate [Ritalin])
c. Antidepressants (e.g., fluoxetine [Prozac])
d. Medications for aggressive behaviors (e.g., carbamazepine [Tegretol])
For medical management to be effective, it must be coordinated with the interdisciplinary team of professionals who use a framework of care based on the principles of being coordinated, culturally sensitive, comprehensive, family-centered, asset-oriented, and community-based.
NURSING ASSESSMENT
The assessment process is comprehensive in scope and based on the dimensions of biophysical, psychosocial, behavioral, and educational needs. Assessment consists of comprehensive evaluation of deficits and strengths related to the following adaptive skills: communication, self-care, social interactions, use of community resources, self-direction, maintenance of health and safety, functional academics, development of leisure and recreational skills, and work. Assessment considers the influence of the child’s cultural and linguistic background, interests, and preferences.
Physical assessment includes measurement of growth (height and weight identified on growth charts) and evaluation for current infections, current status of congenital problems, thyroid functioning, dental care, auditory and visual acuity, nutritional and feeding problems, and orthopedic problems. Physical assessment also involves monitoring for secondary conditions associated with specific diagnoses, such as monitoring for hypothyroidism and depression in those with Down syndrome (for information on Down syndrome, see Chapter 21).
NURSING DIAGNOSES
• Self-care deficit, Bathing/hygiene
• Self-care deficit, Dressing/grooming
• Self-care deficit, Toileting
• Therapeutic regimen management, Ineffective
• Communication, Impaired verbal
• Nutrition: less than body requirements, Imbalanced
• Family processes, Interrupted
NURSING INTERVENTIONS
Infants, Toddlers, and Preschoolers
1. Refer to early intervention program for development of individualized family service plan (IFSP) that is family centered, culturally sensitive, and developmental appropriate (infants from birth to 3 years) or, if child, to community service coordinator/individualized education plan (IEP) coordinator (see Appendix G) providing opportunities for developmental learning (older than 3 years of age) (Appendix B).
2. Refer family to family resource centers and parent information centers that serve parents of children from birth to age 3 who are enrolled in early intervention programs to assist with family support needs, respite care, and sibling needs.
3. Collaborate with other professionals and disability specialists to formulate interdisciplinary plan of care that incorporates lifespan approach with periodic evaluations and assessments of current needs.
4. Serve as health care resource and consultant to child’s disability service coordinator or care manager to ensure child receives comprehensive, accessible, community-based health care provided in inclusive settings.
5. Assist family in obtaining access to care services such as assistive technology, health insurance coverage, dental care, therapy services, income assistance, employment training, advocacy services, and job placement.
6. Refer to other sections in text for specific plans of care for associated special health care needs and health problems.
7. Families are educated about their children’s rights and protections and are supported/encouraged to adovcate on behalf of their children.
8. See the Discharge Planning and Home Care section in this chapter for long-term care.
9. Refer to Box 44-3 for support areas and representative support activities for nursing care needs of children and their families.
Box 44-3 Support Areas and Representative Support Activities
Human Development Activities
• Providing physical development opportunities related to eye-hand coordination, fine motor skills, and gross motor activities
• Providing cognitive development opportunities related to coordinating sensory experiences, representing the world with words and images, reasoning logically about concrete events, and reasoning in more realistic and logical ways
• Providing social-emotional developmental activities related to trust, autonomy, initiative, mastery, and identity
Teaching and Education Activities
• Interacting with trainers or teachers and fellow trainees or students
• Participating in training or educational decisions
• Learning and using problems-solving strategies
• Operating technology for learning
• Accessing training or educational settings
• Learning and using functional academics (e.g., reading signs, counting change)
• Learning and using health and physical education skills
Home Living Activities
Employment Activities
Health and Safety Activities
• Accessing and obtaining therapy services
• Avoiding health and safety hazards
• Communicating with health-care providers
• Accessing emergency services
• Maintaining a nutritious diet
• Maintaining mental health and emotional well-being
• Receiving respiratory care, feeding, skin care, seizure management, ostomy care, and other services for exceptional medical needs
Behavioral Activities
• Learning specific skills or behaviors
• Learning or making appropriate decisions
• Accessing and obtaining mental health treatments
• Making choices and taking initiatives
• Incorporating personal preferences into daily activities
• Learning or using self-management strategies
Social Activities
• Socializing within the family
• Participating in recreation or leisure activities
• Making appropriate sexuality decisions
• Socializing outside the family
• Associating and dissociating from people
• Communicating with others about personal needs
• Using appropriate social skills
Protection and Advocacy Activities
From American Association on Mental Retardation: Mental retardation: definition, classification, and systems of supports, ed 10, Washington, DC, 2002, The Association.
School-Aged Children
1. Collaborate with other professionals and disability specialists to formulate interdisciplinary plan of care that incorporates life-span approach with periodic evaluations and assessments of current needs.
2. Encourage family with child-rearing practices that support child’s acquisition of skills related to communication skills, personal care, social interactions, household tasks, and health care self care.
3. Collaborate with members of the special education team in IEP development on identifying health-related needs that affect academic performance and adaptive functioning and to ensure that the child’s educational program is provided in an inclusive enrivonment.
4. Collaborate with disability service coordinator or case manager to ensure that ongoing health-related needs associated with long-term disability management and primary care needs are addressed and that health care is community-based, appropriate, accessible, comprehensive, and provided in inclusive settings.
5. Assist family in obtaining access to care services such as health insurance coverage, dental care, therapy services, after-school programs, recreational programs, advocacy services, and social skills and mobility training.
6. Parents are encouraged to learn and advocate for their children’s rights and protections and to foster the development of their children’s advocacy.
7. Refer parents to family support services, such as parent-to-parent support to assist them in coping with the needs of their children with an intellectual disability and challenges of living with a child with an intellectual disability.
8. Refer to the Discharge Planning and Home Care section in this chapter.
9. Refer to Box 44-3 for support areas and representative support activities for nursing care needs of school-aged children and their families.
Adolescents
1. Collaborate with other professionals and disability specialists to formulate interdisciplinary plan of care that incorporates life-span approach with periodic evaluations and assessments of current needs.
2. Refer to other sections in text for special health care needs and health problems.
3. Collaborate with members of the IEP team in IEP transition planning to identify health-related needs that affect academic performance and adaptive functioning, acquisition of community living skills, access to sex education, and work-based instruction and on-the-job training; and promote inclusive approaches in the IEP.
4. Encourage family with child-rearing practices that support child’s acquisition of skills related to communication skills, personal care, sexuality, social interactions, and household tasks (remember, the child will have a number of options as to what his or her life goals are).
5. Coordinate with health care transition specialist to ensure that health insurance coverage continues when pediatric eligibility terminates, to transfer individual from pediatric to adult health care specialty and primary care professionals, and to ensure learning of health self-care skills.
6. Collaborate with disability service coordinator or case manager to ensure that ongoing health-related needs associated with long-term disability management and primary care needs are addressed.
7. Assist youth and family with transition access to care services such as health insurance coverage, dental care, therapy services, postsecondary training and education, employment training and placement, income assistance, rehabilitation services, recreational and leisure services, social and advocacy groups, and community living and mobility training (use of transportation).
8. Refer to family support services to assist family members in “letting go” of their adolescent in transition and to support him or her during the process.
9. Youth are encouraged to participate as fully as possible in decision making affecting their lives, and realize that they are fully informed of their legal rights and protections.
10. Refer to the Discharge Planning and Home Care section in this chapter.
11. Refer to Box 44-3 for support areas and representative support activities for nursing care needs of youth and young adults.
Discharge Planning and Home Care
1. Refer child and family to agencies and professionals who can provide specialized health care services related to well-child and well-adolescent care and dental care and hygiene; health care provided must be appropriate to needs, community-based, accessible, and comprehensive.
2. Refer family to community resources for genetic counseling, financial assistance, adaptive equipment supply, and family support services.
3. Collaborate with families as needed in developing and implementing behavior treatment plan.
4. Facilitate learning of appropriate social, community, communication, community safety, healthy sexuality and stranger avoidance skills, and development of peer relationships and leisure and recreational interests.
5. Facilitate child’s inclusion into early intervention and educational programs, recreational programs, and community settings.
6. Coordinate services with members of infant, child, or youth’s interdisciplinary team in early intervention (IFSP) or educational (IEP) settings. Refer to Appendix G.
7. Ensure that if the appointment of guardian is necessary, the individual is fully informed about the child or youth’s health-related needs.
8. Ensure that children and youth with intellectual disabilities participate in decision making as fully as possible and are informed of their rights and protections.
CLIENT OUTCOMES
1. Child or youth and family will express overall satisfaction as measured by quality-of-life indicators.
2. Family and child or youth will cope with challenges of living with disability.
3. Family will be adept in accessing community resources.
4. Child or youth will demonstrate autonomy, self-determination, and self-advocacy behaviors.
5. Youth will graduate from high school or obtain a high school certificate.
6. Youth will have acquired school-based work experience as precursor for adult employment.
7. Child or youth will have participated in inclusive school and community-based activities.
8. Child or youth will have age-appropriate social relationships with peers with and without disabilities.
9. Youth will have access to sex education enabling healthy sexuality, responsible sexual expression, and protection from sexual exploitation and abuse.
American Association on Mental Retardation, The ARC. Mental retardation: definition, classification, and systems of supports, ed 10. Washington, DC: The Association, 2002.
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