Familial retardation is an obsolete term for mild intellectual disability attributed to environmental or idiopathic (unknown) causes and generally involving some degree of psychosocial disadvantage.
The term familial retardation is no longer used to describe children with mild intellectual disability (ID) that cannot be traced to either genetic or physical causes. Genetic causes account for about 25% of cases of ID and include such disorders as Down syndrome, phenylketonuria, Klinefelter syndrome, and fragile X syndrome. Physical causes of ID account for another 12% of cases and include trauma, problems of pregnancy (fetal alcohol syndrome, rubella, maternal malnutrition), and difficulties in the perinatal period (most often brain damage during a difficult delivery).
Until late in the twentieth century, familial or sociocultural retardation was a catchall category for the 50–80% of children whose intellectual limitations are the result of being born to parents with intellectual disabilities, along with environmental factors that include parental indifference to or rejection of the child; cultural or subgroup attitudes that disparage intellectual achievement; institutionalization; or sensory deprivation. Familial retardation as a category was never clearly defined—a fact noted by several researchers who investigated it from the 1960s into the early 2000s. As early as 1967, one investigator observed, “Considerable order could be brought to the area if, instead of viewing all retardates as a homogeneous group arbitrarily defined by some IQ score, workers would clearly distinguish between the group of retardates known to suffer from some organic defect and the larger group of retardates referred to as familial retardates. It is the etiology of familial retardation that currently constitutes the greatest mystery.”
In 2013, the American Psychiatric Association(APA) followed the World Health Organization and groups such as the American Association on Intellectual and Developmental Disabilities (AAIDD) in replacing the general term mental retardation with the phrase intellectual disability (ID) or intellectual development disorder (IDD) in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). The reason for the change is that mental retardation had come to be regarded as a stigma or insult. The historical irony here is that the term mental retardation itself was coined in the 1950s to replace terms such as feeble-minded or moron.
In addition to the change in terminology, the APA introduced a broader set of criteria for mild ID. While a child's IQ score on a standardized test is still recorded, the new definition of ID comprises three domains:
The APA notes that the diagnosis of a child as having mild ID requires a careful clinical evaluation in addition to administration of a standardized IQ test.
The reason for the new criteria is that children may demonstrate different levels of ability in the three domains that affects their adaptive functioning in ways that the IQ score alone cannot reveal. For example, some children with mild ID may have relatively high cognitive skills but severe deficits in interpersonal skills—or the reverse. While mild ID is still characterized as an IQ score two standard deviations below the average, or about 70, the IQ score is no longer the sole determinant of the child's classification as having ID. In addition to evaluating the child in the three domains specified by the APA, the AAIDD urges mental health professionals to take into account language differences among children; cultural differences in the way people talk, move, and behave; and “the community environment typical of the individual's peers and culture.”
Another distinction that is relevant to the APA's changes in nomenclature and diagnostic criteria is the classification of ID as either syndromic (associated with a genetic disorder and characterized by physical malformations or abnormalities) or nonsyndromic (not associated with a genetic disorder and lacking physical deformities). What was formerly termed familial retardation is now identified as nonsyndromic ID.
In general, intellectual disability affects between 1% and 3% of the population of the United States, with 75–90% of affected persons having mild ID. Environmental causes thought to contribute to nonsyndromic ID include the quality of the mother's prenatal care, maternal and child nutrition, family size, the spacing of births within a family, disease, and health risks from such environmental toxins as lead.
The DSM-5 diagnostic criteria for mild nonsyndromic ID do not specify an exact age for evaluation but state that “an individual's symptoms must begin during the developmental period and are diagnosed based on the severity of deficits in adaptive functioning.” In many cases, intellectual deficits are not apparent until children begin school. Mild ID is considered a chronic disorder. Children with mild nonsyndromic ID are at increased risk of a concurrent mental disorder; between 40% and 70% have such conditions as depression, attention-deficit/hyperactivity disorder, and autism spectrum disorder.
See also Diagnostic and Statistical Manual ofMental Disorders (DSM-5); Intellectual disability.
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American Association on Intellectual and Developmental Disabilities (AAIDD), 501 3rd St. NW, Ste. 200, Washington, DC, 20001, (202) 387-1968, Fax: (202) 387-2193, http://aaidd.org .
American Psychiatric Association, 1000 Wilson Blvd., Ste. 1825, Arlington, VA, 22209, (703) 907-7300, (888) 3577924, firstname.lastname@example.org, http://psychiatry.org .