What is Mental Retardation?

Mental retardation is a condition characterized by limitations in performance that result from significant impairments in measured intelligence and adaptive behavior that occurs before age 18. This is a condition of both clinical and social importance. Introduction Mental retardation also confers a social status that can be more handicapping than the specific disability itself. The determinants of competence in any individual are complex and multifactorial. Regardless of his or her level of performance, each child's abilities are influenced by both the integrity and the maturational status of the nervous system and by the nature and quality of his or her life experience. Some children sustain significant neurological insults and develop normal skills. Others manifest severe cognitive impairment despite the absence of recognizable focal neurological findings or historical evidence of significant risk factors for CNS dysfunction. Incidences Approximately 3% of the general population has an IQ less than two standard deviations below the mean. It has been estimated that 80-90% of persons with mental retardation function within the mild range, whereas only 5% of the population with mental retardation is severely to profoundly impair. Causes Table 1 lists potential contributing factors in the pathogenesis of mental retardation from preconception through the early childhood years. Clinical Menifestation
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Failure to meet intellectual developmental markers Persistence of infantile behavior Lack of curiosity Decreased learning ability Inability to meet educational demands of school

Table 2 lists a number of atypical physical features that have been associated with a higher incidence of mental retardation. Mental retardation may suggest syndromes that are associated with mental retardation should be identified at birth or during early infancy e.g. Down syndrome, fetal alcohol syndrome, and primary microcephaly are examples of such conditions.

Deviations in normal adaptive behaviors depend on the severity of the condition. Mild retardation may be associated with a lack of curiosity and quiet behavior. Severe mental retardation is associated with infantile behavior throughout life. Although youngsters with severe impairment show marked delays in psychomotor skills in the first year of life, children with moderate retardation typically exhibit normal motor development and present with delayed speech and language abilities in the toddler years. Mild retardation, on the other hand, may not be suspected until after entry into school, although participation in an organized preschool or child-care program can highlight discrepancies in the performance of a young child with significantly sub average abilities. Classification Recently categories of mild, moderate, severe and profound retardation have been replaced by a classification system that specifies four levels of support systems needed for daily functioning (i.e., intermittent, limited, extensive and pervasive).

Mental efficiency Ultimately, the diagnosis of mental retardation requires confirmation of significantly sub average general intellectual functioning (i.e., an IQ standard score of 70-75 or below) in association with deficits in two more of the following ten adaptive skill areas: communication, self-care, home living, social skills, community use, self-direction, health and safety, functional academics, leisure, and work. Diagnosis
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Parental report, and, caregiver or teacher report gives the initial clue that this child needs further evaluation. A comprehensive history, physical examination, and laboratory evaluation often lead to identification of specific factors. This finding follows developmental assessment and systemic evaluation. A range of laboratory studies must be considered in the medical evaluation including karyotypes. It should be kept in mind that a diagnosis of mental retardation relies on an assessment of adaptive behavior and not solely on IQ, the epidemiology varies with the life cycle.

Neuropathology Mental retardation is multifactor and neuropathology varies with the cause. Biological studies It has been observed that irrespective of the cause of mental retardation, brain perfusion defects have been observed in various areas of brain. This finding is of significance since the central theme of treatment common to all efforts to treat and prevent mental retardation is the promotion

of healthy brain development and the provision of a nurturing and growth-promoting environment. cognitive
Deficits in cognitive functioning are the defining feature of mental retardation.Cognitive abilities-as measured by intelligence tests-are the first criteria indetermining whether an individual is cognitively disabled. There may be atemptation to assume a person having low measured intelligence is functioning lowacross the board. But, this is rarely the case. Each individual has a unique set of cognitive strengths and weaknesses. Likewise, the population called mentallyretarded has general cognitive strengths and weaknesses that must be examined insome detail if we are to understand how deficiencies in cognitive functioning maycontribute to difficulties with language and communication.Let's look at three areas of cognitive functioning that have been researchedextensively with regard to mental retardation: attention, organization, and memory Children with mental retardation have been reported to have problemsdiscriminating the important features of a task and attending to more than onedimension at a time (Zeaman & House, 1979). For example, if asked to sort objectson the basis of both size and color, most children with mental retardation wouldhave difficulty. On the other hand, their ability to sustain attention has been foundto be as good, or better than, mental-agematched peers (Karrer, Nelson, &Galbraith. 1979).Individuals with mental retardation have been described as having difficultyorganizing information for recall (Spitz, 1966). This is an important skill. Forexample, if you" were asked to remember the following list of items, you You would probably recognize that these items comprise three groups: toys, fruit,and tools. When asked to recall the items, you would probably report them in thesethree groups. Typically, children with mental retardation do not spontaneouslyrecognize or use these groups for recall (Stephens, 1972).Memory difficulties have long been associated with mental retardation.However, as we learn more about memory, we learn that people with mentalretardation have both strengths and weaknesses in this domain. Long-termmemory, for example, has been found to be relatively intact in most persons withmental retardation (Belmont, 1966). However, problems with short-term memoryare frequently reported (Ellis, 1970). One explanation for the observed problemswith short-term memory is that people with mental retardation have inefficientrehearsal strategies (Bray, 1979). In order to remember information, you have tostore it. [f you want to remember a telephone number for just a few seconds, it isusually enough to repeat the number over and over. But, if you want to rememberthe number for a few minutes or a few days or more, you need .to store it in a waythat is retrievable. For example, a phone number with the last four digits 1488might be remembered by recalling 1492 (the year Columbus landed in theAmericas) minus 4 (1488). People with mental retardation tend to use rehearsalstrategies that do not enhance their recall. They tend to persist with inefficientstrategies (such as repetition) that do not always work.Another specific cognitive impairment associated with mental retardation isgeneralization of information. Persons with mental retardation have often beendescribed as having difficulty applying what they have learned previously to use innew settings, with different people, or in new ways (Stephens, 1972). Generalizationis a critical skill for learning. If students do not know when

and where to apply theirskills, they have really learned nothing. Therefore, it is essential that students withmental retardation be taught in ways that will increase their likelihood of generalization. Conversational competence
How effective are persons with mental retardation as conversational partners?People with mental retardation have often been described as passivecommunicators who wait for others to take the lead in conversations (Bedrosian &Prutting, 1978). However, people who have worked or lived with individuals withmental retardation have often found them to be very outgoing-often to the point of being intrusive. How can we reconcile the research findings with experience?Perhaps the answer lies in the selection criteria of the population to bestudied. Kuder and Bryen reported the results of a study in which they observedresidents in a private institution interacting with staff in a classroom and in aresidential setting (1991). They found that, in general, the residents initiatedinteraction with staff. For their study, they selected subjects who were capable of verbal communication. Previous studies (e.g., Prior, Minnes, Coyne, Golding, Hendy,& McGillivray, 1979) had included all of the residents in an institution, includingsome who may have been unable to engage in verbal interaction. Not surprisingly,by selecting only subjects who could talk, Kuder and Bryen found much morefrequent initiation of conversation than had been previously reported. There is more to conversational competence than simply being involved ininteraction; there are qualitative aspects as well, such asjura taking, topicmanagement, and conversational repair. The conversational competence of personswith mental retardation has been studied in each of these areas, in normalconversations, participants take turns talking. Occasionally they talk at the sametime, but imagine what it would be like if we all talked at the same time all of thetime. Persons with mental retardation have been found to have few problems withturn taking. Studies of the conversational turn taking in young children with mentalretardation (Tannock, 1988), as well as adults (Abbeduto & Rosenberg, 1980), havefound that they take turns in conversations and make few errors, much asnondisabled people do.Although people with mental retardation appear capable of taking their turnin a conversation, what is even more important is what they do with that turn. Typically, people with mental retardation do not make significant contributions tomaintaining the conversation (Abbeduto, 199 I). They may make comments, such as ok or umn-umn . but_do not extend the topic by adding new information.Research on the conversational skills of people with mental retardation hasalso found that they have difficulty_repairing_conversations_that break down. If youare talking with someone else and do not understand what is being said, you will dosomething to clarify the conversation. You will say what? or excuse me as a signal tothe speaker that you do not understand. People with mental retardation have beenfound to be capable of using such conversational repairs, but fail to use them whenthey are needed (Robinson &. Whittaker, 1986; Abbeduto. Davies, Solesby, &Furman, 1991). Children with mental retardation have also been found to be slow in esponding to clarification requests made by others (Scherer <fc Owings,

1984).Moreover, researchers have found that the development of conversational repairskills appears to plateau during the school years and not improve with experience(Abbeduto, Short-Meyerson, Benson, & Dolish, 1997).In considering all of the research on the communicative abilities of personswith mental retardation, Abbeduto (1991) concluded that "deficits in verbalcommunication are a defining feature of mental retardation and should figureprominently in assessments of adaptive behavior" (p. 108). Although problems withverbal communication do seem to be quite common among people with mentalretardation, there is considerable variability within the population.Obviously, the ability to engage in effective communication with others is a criticalskill for classroom success. Teachers and other education professionals should bealert to the problems that students with mental retardation may have in expressingthemselves and understanding others. Placing students in heterogeneous groupscan be a good way to encourage communicative interaction, if the groups are wellmanaged and the group activities carefully chosen