Intellectual Disability

Intelligence is both genetically and environmentally determined. Children born to parents with intellectual disability are at increased risk of a range of developmental disabilities, but clear genetic transmission of intellectual disability is unusual. Although advances in genetics, such as chromosomal microarray analysis and whole genome sequencing of the coding regions (exome), have increased the likelihood of identifying some causes of intellectual disability, a cause of intellectual disability in a specific person often cannot be identified. A cause is most likely to be identified in severe cases. Deficits in language and personal–social skills also may be due to emotional problems, environmental deprivation, learning disorders Overview of Learning Disorders Learning disorders are conditions that cause a discrepancy between potential and actual levels of academic performance as predicted by the person’s intellectual abilities. Learning disorders... read more , or deafness Hearing Impairment in Children Common causes of hearing loss are genetic defects in neonates and ear infections and cerumen in children. Many cases are detected by screening, but hearing loss should be suspected if children... read more rather than intellectual disability.

The primary manifestations of intellectual disability are

Some children with mild intellectual disability may not develop recognizable symptoms until preschool age. However, early identification is common among children with moderate to severe intellectual disability and among children in whom intellectual disability is accompanied by physical abnormalities or signs of a condition (eg, cerebral palsy Cerebral Palsy (CP) Cerebral palsy refers to a group of nonprogressive conditions characterized by impaired voluntary movement or posture and resulting from prenatal developmental malformations or perinatal or... read more ) that may be associated with a particular cause of intellectual disability (eg, perinatal asphyxia). Delayed development is usually apparent by preschool age, often manifesting more as delay in communication than in motor skills. Among older children, hallmark features are a low IQ combined with limitations in adaptive behavior skills (eg, communication, self-direction, social skills, self-care, use of community resources, maintenance of personal safety). Although developmental patterns may vary, it is much more common for children with intellectual disability to experience slow progress than developmental arrest.

Behavioral problems are the reason for most psychiatric referrals and out-of-home placements for people with intellectual disability. Behavioral problems are often situational, and precipitating factors can usually be identified. Factors that predispose to unacceptable behavior include

In institutional settings (now uncommon in the US), overcrowding, understaffing, and lack of activities contribute to both behavior challenges and to limited functional progress. Avoidance of long-term placement in large congregate care settings is extremely important in maximizing the individual's success.

Prenatal testing can be done to determine whether the fetus has abnormalities, including genetic disorders, that predispose to intellectual disability.

From birth on, growth and development Childhood Development Descriptions of development are often divided into specific domains, such as gross motor, fine motor, language, cognition, and social/emotional growth. These designations are useful, but substantial... read more , including cognitive ability, are routinely assessed at well-child visits. For suspected cases of intellectual disability, development and intelligence are assessed in greater detail, typically by early intervention or school staff.

Establishing intellectual disability is followed by efforts to determine a cause, often including central nervous system (CNS) imaging and genetic and metabolic testing. Accurate determination of the cause may provide a developmental prognosis, suggest plans for educational and training programs, help in genetic counseling, and relieve parental guilt.

Many people with mild to moderate intellectual disability can support themselves, live independently, and be successful at jobs that require basic intellectual skills.

Life expectancy may be shortened, depending on the etiology of the disability, but health care is improving long-term health outcomes for people with all types of developmental disabilities. People with severe intellectual disability are more likely to require life-long support. The more severe the cognitive disability and the greater the immobility, the higher the mortality risk.

Treatment and support needs depend on social competence and cognitive function. Referral to an early intervention program during infancy may prevent or decrease the severity of disability resulting from a perinatal insult. Realistic methods of caring for affected children must be established.

Family support and counseling are crucial. As soon as intellectual disability is confirmed or strongly suspected, the parents should be informed and given ample time to discuss causes, effects, prognosis, education and training of the child, and the importance of balancing known prognostic risks against negative self-fulfilling prophecies in which diminished expectations result in poor functional outcomes later in life. Sensitive ongoing counseling is essential for family adaptation. If the family’s physician cannot provide coordination and counseling, the child and family should be referred to a center with a multidisciplinary team that evaluates and serves children with intellectual disability; however, the family’s physician should provide continuing medical care and advice.

A comprehensive, individualized program is developed with the help of appropriate specialists, including educators.

A multidisciplinary team includes

Affected children with concomitant mental health disorders such as depression may be given appropriate psychoactive drugs in dosages similar to those used in children without intellectual disability. Use of psychoactive drugs without behavioral therapy and environmental changes is rarely helpful.

Every effort should be made to have children live at home or in a community-based residence. Living at home with the family is usually better for the child than alternative placements unless marked behavior difficulties require a higher level of supervision than the family can provide. The family may benefit from psychologic support and help with daily care provided by day care centers, homemakers, and respite services. The living environment must encourage independence and reinforce learning of skills needed to accomplish this goal.

Whenever possible, children with intellectual disability should attend an appropriately adapted day care center or school with peers without cognitive disability. The Individuals with Disabilities Education Act (IDEA), the primary US special education law, stipulates that all children with disabilities should receive appropriate educational opportunities and programs in the least restrictive and most inclusive environments. The Americans with Disability Act and Section 504 of the Rehabilitation Act also provide for accommodations in schools and other public settings.

As people with intellectual disability reach adulthood, an array of supportive living and work settings is available. Large residential institutions are being replaced by small group or supported individual residences matched to the individual's functional abilities and needs.

Vaccines Childhood Vaccination Schedule Vaccination follows a schedule recommended by the Centers for Disease Control and Prevention (CDC), the American Academy of Pediatrics, the American Academy of Family Physicians, and the American... read more have all but eliminated congenital rubella and pneumococcal and H. influenzae meningitis as causes of intellectual disability.

Fetal alcohol syndrome Fetal Alcohol Syndrome Alcohol exposure in utero increases the risk of spontaneous abortion, decreases birth weight, and can cause fetal alcohol syndrome, a constellation of variable physical and cognitive abnormalities... read more is a highly common and totally preventable cause of intellectual disability. Because it is unknown when during pregnancy alcohol is most likely to harm the fetus and whether there is a lower limit of alcohol use that is completely safe, pregnant women should be advised to avoid all alcohol intake.

Folate supplementation (400 to 800 mcg orally once a day) in women beginning 3 months before conception and continuing through the 1st trimester reduces the risk of neural tube defects (see prevention of congenital neurologic anomalies Prevention Spina bifida is defective closure of the vertebral column. Although the cause is not known, low folate levels during pregnancy increase risk. Some children are asymptomatic, and others have... read more ).

Continuing improvements in, and increased availability of, obstetric and neonatal care and the use of exchange transfusion and Rho(D) immune globulin to prevent hemolytic disease of the newborn have reduced the incidence of intellectual disability; the increase in survival of very low-birth-weight infants has kept the prevalence constant.

The following are English-language resources that may be useful. Please note that THE MANUAL is not responsible for the content of these resources.