Behavioral phenotypes and special education: parent report of educational issues for children with Down syndrome, Prader-Willi syndrome, and Williams syndrome.

Author/s: Deborah J. Fidler
Issue: Summer, 2002 Journal of Special Education

This study examined the degree to which parents are informed about syndrome-based behaviors in children with three genetic mental retardation syndromes: Down syndrome (n = 21), Prader-Willi syndrome (n = 25), and Williams syndrome (n = 21). Parents were informed regarding blatant behavioral features associated with their children's syndromes (especially concerning maladaptive behaviors) but were less informed about certain subtle syndrome-based cognitive processing outcomes. Compared to the parents of children with the other two syndromes, parents of children with Down syndrome were more informed about syndrome-related behaviors; in addition, greater numbers of individuals (e.g., parents, school psychologists, teachers, speech-language pathologists) brought information about children with Down syndrome into the classroom setting. Across all three groups, the supportive educational services received by the children were generally not adjusted to syndrome profiles.

Over the past decade, a quiet transformation has taken place in behavioral research on persons with mental retardation. In earlier years, researchers compared persons with mild, moderate, severe, and profound levels of mental retardation. Recently, however, increasing numbers of studies have divided research groups by participants' etiology or cause of mental retardation. Comparing the 1980s to the 1990s, the numbers of behavioral studies increased from 10 to 81 for Williams syndrome, from 24 to 86 for Prader-Willi syndrome, and from 60 to 149 for Fragile X syndrome. Even for Down syndrome, the sole disorder with a long-standing tradition of behavioral research, the number of behavioral studies almost doubled, rising from 607 articles during the 1980s to 1,140 articles during the 1990s (Dykens & Hodapp, 2001).

Alongside this increase in quantity has come increased knowledge about behavior in many of these disorders. Indeed, there now exists an entire field of researchers devoted to examining whether different genetic mental retardation syndromes show specific "behavioral phenotypes" (Dykens, Hodapp, & Finucane, 2000; O'Brien & Yule, 1995). Although the term has been variously defined, most researchers now agree that a behavioral phenotype involves "the heightened probability or likelihood that people with a given syndrome will exhibit certain behavioral and developmental sequelae relative to those without the syndrome" (Dykens, 1995, p. 523). This definition highlights the increased likelihood--but not certainty--that any individual with a specific genetic mental retardation disorder will show particular etiology-related behaviors.

The present study examines the degree to which parents know about education-related behaviors in the three genetic disorders of Down syndrome, Prader-Willi syndrome, and Williams syndrome. Before presenting this study, however, we review recent behavioral findings concerning each disorder. With this evidence as background, we can then assess the degree to which parents know about their children's etiology-related behaviors. Our goal involves the possibility that knowledge of such behaviors might ultimately lead to etiology-informed intervention strategies, an issue we revisit later.

Etiology-Related Behaviors in Three Genetic Mental Retardation Syndromes

By choosing to study parents' knowledge of their children with Down syndrome, Williams syndrome, and Prader-Willi syndrome, we follow our earlier work of describing behaviors in each syndrome (Hodapp & Fidler, 1999). We again note, however, that while work on behavior in genetic mental retardation disorders has accumulated at a dizzying pace, most studies are limited to only a few well-described disorders.

Down syndrome is the most common genetic (chromosomal) cause of mental retardation, caused in almost all cases by a third Chromosome 21. In addition to particular genetic and physical features, most children with Down syndrome display specific problems in linguistic grammar, expressive language, and articulation. For example, most children with Down syndrome do not progress grammatically beyond the 3-year level, and their grammatical abilities almost invariably fall below their overall mental age levels (Fowler, 1990). Similarly, skills in expressive language, as opposed to those in receptive language, are much more delayed. Indeed, by the time children's mental ages reach 24 months, significant delays (6+ months) in expressive language abilities are evident in 83% to 100% of children with Down syndrome (Miller, 1999). Regarding articulation, 95% of parents report that others show at least occasional difficulties understanding the speech of their child with Down syndrome (Kumin, 1994).

Conversely, other areas are relatively strong in most children with Down syndrome. On average, schooll-age children with Down syndrome show levels of visuo-spatial short-term memory that are ! or more years advanced over identical auditory or verbal short-term memory tasks (see Hodapp, Evans, & Gray, 1999, for a review). Such relative strengths arise even when subtests from different psychometric instruments are used to measure verbal short-term memory and when researchers use either scaled (Pueschel, Gallagher, Zartler, & Pezzullo, 1987) or age-equivalent scores in their analyses (e.g., Hodapp et al., 1992). As a group, therefore, children with Down syndrome show significant (more than mental-age level) deficits in grammar, expressive language, and articulation, as well as relative strengths in visual short-term memory tasks.

A second well-studied disorder, Prader-Willi syndrome, is caused by missing genetic material from the Chromosome 15 derived from the father (either a deletion on the paternally derived 15 or two Chromosome 15s from the mother). Many children with Prader-Willi syndrome show relative weaknesses on tasks involving sequential processing (i.e., consecutive order in problem solving). In contrast, these children perform well on tasks requiring simultaneous processing (i.e., integration and synthesis of stimuli as a unified whole). In one study of teens and young adults with Prader-Willi syndrome, average age-equivalent scores for simultaneous processing were almost 2 years more advanced than those for sequential processing (7.10 years vs. 5.29 years; Dykens, Hodapp, Walsh, & Nash, 1992).

In addition to their profile of cognitive processing, children with Prader-Willi syndrome show extreme hyperphagia (i.e., overeating) and obsessive-compulsive behavior. Hyperphagia has long been considered the hallmark of Prader-Willi syndrome (Holm et al., 1993), but it also now appears that many of these children show other obsessions and compulsions. Comparing individuals with Prader-Willi syndrome to same-age nonretarded persons diagnosed with obsessive-compulsive disorder (OCD), Dykens, Leckman, and Cassidy (1996) found few differences between the two groups on behaviors such as hoarding objects (e.g., toiletries, paper, pens); ordering and arranging objects by color, size, or shape, or until they were "just right"; needing to say or tell things; or redoing behaviors (e.g., tying and untying shoes). Across 100 individuals with Prader-Willi syndrome, 94% showed obsessions (thoughts) and 71% showed compulsions (behaviors). Joined with overeating (98%) and temper tantrums (88%), these children showed extremely high levels of maladaptive behavior (Dykens & Cassidy, 1996; Dykens & Kasari, 1997).

A third well-researched disorder, Williams syndrome, is caused by a microdeletion on Chromosome 7. Children with this syndrome generally show a characteristic "elfin-like" facial appearance, along with heart and other health problems (Pober & Dykens, 1996). As many as 95% of these children suffer from hyperacusis, or hypersensitivity to sound (Van Borsel, Curfs, & Fryns, 1997).

Apart from these medical issues, recent attention has strongly focused on the interesting--and possibly unique--cognitive-linguistic profile shown by most of these children. Children with Williams syndrome show relative strengths in language; for many years it was thought that these children might even perform at chronological-age levels on a variety of linguistic tasks (Bellugi, Wang, & Jemigan, 1994). Although age-appropriate performance in language has now been found in only small percentages of children with Williams syndrome (Mervis, Morris, Bertrand, & Robinson, 1999), these children nevertheless show relative strengths in language, as well as in verbal processing and in some areas of music (Lenhoff, 1998).

Conversely, many children with Williams syndrome perform especially poorly on a variety of visuo-spatial tasks. In a recent study, Mervis et al. (1999) found that 47 of 50 children with Williams syndrome showed the pattern of weakness in visuo-spatial tasks and a relative strength in various measures of language (e.g., vocabulary, grammar, short-term auditory memory; see also Udwin & Yule, 1991; Udwin, Yule, & Martin, 1987). Although not every child with Williams syndrome shows linguistic strengths and visuo-spatial weaknesses, the large majority do.

Children with Williams syndrome also show a wide variety of anxieties and fears. A recent study compared the fears reported by children with Williams syndrome to those reported by other children with mental retardation (Dykens, in press). A majority of the children with mental retardation reported only two fears--their parents getting sick and getting a shot or injection. In contrast, more than half of the group with Williams syndrome endorsed 41 different fears. Some involved interpersonal issues like being teased (92%), getting punished (85%), and getting into arguments with others (85%). Others involved physical issues, such as getting shots or injections (90%), being in a fire or getting burned (82%), and getting stung by a bee (79%). Still others related to these children's hyperacusis or clumsiness (loud noises such as sirens, 87%; falling from high places, 79%; thunderstorms, 78%). Though not every child with Williams syndrome shows any or all of these fears, the vast majority do appear to be overly fearful compared to most children with mental retardation.

Two themes emerged when we summarized this large and growing literature. First, in every instance there seems to be a combination of strong group differences, albeit with some within-group variation. Second, almost all of these studies date to the 1990s, most to the past 5 years. Given how recent these findings are, it remains unclear just "who knows what" about such striking etiology-related behaviors. In two earlier studies, teacher knowledge was examined relative to the two most common genetic forms of mental retardation, Down syndrome and Fragile X syndrome (Wilson & Mazzocco, 1993; York, yon Fraunhofer, Turk, & Sedgwick, 1999). Both studies found that teachers were more informed about the outcomes associated with Down syndrome than those associated with Fragile X syndrome. One study concluded that the practitioners surveyed did not demonstrate a sufficient knowledge of Fragile X syndrome to ensure that the needs of these children would be met in a classroom (York et al., 1999).

To date, no studies exist examining parent behavioral knowledge about children with Down syndrome, Williams syndrome, and Prader-Willi syndrome. Because parents are often a prominent force in the design of children's educational programs--attending IEP meetings, advocating for services, and advising teachers on their children's needs--we propose that the measure of parent knowledge of child educational characteristics serves as an indicator of whether etiology-related characteristics are being considered in special education. In addition, we assess the degree to which those phenotypic characteristics highlighted by researchers in current research have become salient to those who know these children best, their parents.

This study, then, presents the first exploration of parental knowledge about the educationally related behaviors of children with these three genetic mental retardation disorders. Because no body of work currently exists, we devised our own questionnaire and chose among those etiology-related behaviors that seemed most relevant to the school context. Using these methods, we hope to gain important, albeit preliminary, information as to what parents know about their children's behavior, how services are matched to etiology-related behavior, and who brings etiology-related behavioral information into the classrooms of children with Down syndrome, Williams syndrome, and Prader-Willi syndrome.

Method

Participants

Participants were parents of three groups of 5- to 21-year-old children and adolescents: 21 with Down syndrome, 25 with Prader-Willi syndrome, and 21 with Williams syndrome. As shown in Table 1, children in each of the three groups were an average of 11 to 12 years of age, and most showed mild or moderate levels of mental retardation. In each group, most children were attending general education classes, either full-time or part-time, with smaller percentages in special education classrooms. Mothers were the main respondents, and mothers and fathers' levels of education were generally high (most had completed college in each group). Families of children in this study were primarily middle class, and all children were currently living at home.

Procedure

Parents were recruited through local and national parent organizations for each of these three syndromes. Initial contact was established through in-person announcements made at parent organization events by the third author. Those interested filled out a form stating they would like to volunteer to participate in research. Parents who volunteered were sent a battery of questionnaires, which they completed and then returned to the researchers via mail. Parents received a coupon for a $3 cup of coffee at Starbucks along with their packet of questionnaires, but no other compensation was offered. In a small number of cases (fewer than 5), reminder phone calls were made to increase the response rate. The large majority of those parents expressing an interest in this study completed the questionnaires.

In addition to basic demographic information about themselves, their families, and their children, parents also completed questionnaires regarding their children's cognitive strengths and weaknesses, maladaptive behaviors, and current educational placement. No returned questionnaires were excluded from the analyses.

Measures

Demographics Questionnaire. This questionnaire asked parents about diagnostic information (when diagnosed and at which hospital), the child's level of intellectual impairment (borderline, mild, moderate, or severe mental retardation), mad information about parents' age, education level, and ethnicity.

Educational Experiences Questionnaire. The educational experiences questionnaire was designed specifically for this study. Items were chosen from well-established research findings on cognitive strengths and weaknesses and maladaptive behavior profiles for children with each of these disorders. For example, items pertaining to visual and verbal learning in Down syndrome and Williams syndrome are drawn from a rich literature on verbal and visuospatial processing strengths and weaknesses in these two syndromes (Hodapp et al., 1992; Jarrold, Baddeley, & Hewes, 1999; Klein & Mervis, 1999; Pueschel et al., 1987; Udwin & Yule, 1991; Wang & Bellugi, 1994). Though no piloting was done with this questionnaire, colleague reviews led to revisions improving language, phrasing, and ease of use prior to distribution.

Current placement. The first set of questions on the educational experiences questionnaire related to the child's current educational placement. Parents described whether the child was currently fully included, partially mainstreamed, or in a special day class without mainstreaming. They also rated their satisfaction with the child's current placement on a 5point scale (1 = very dissatisfied, 5 = very satisfied) and whether they had considered changing placements.

Support services. Parents were asked whether their children currently received any of the following services: speech therapy, physical therapy, occupational therapy, extra reading, extra writing, extra math, adaptive physical education, aide in the classroom, social skills training, psychological counseling, and one-on-one aide. Parents were then asked whether they would like their children to receive more of these services.

Learning profile. Parents were asked to rate the degree to which their child fit six statements concerning cognitive-linguistic behaviors and three concerning behavior problems on a 5-point Likert scale (1 = not at all, 3 = somewhat, and 5 = very much). Cognitive-linguistic functioning items included the following: is a visual learner (DS = strength; WS = weakness); is verbally expressive (WS = strength; DS = weakness); is an auditory learner (WS = strength; DS = weakness); learns through music (WS = strength); learns well by being given the "big picture" (PWS = strength); and needs material broken down into small steps/parts (PWS = weakness). Behavior problem items included the following: is frightened by loud noises (WS); needs things to be "just right" (is perfectionistic; PWS); overeats (PWS).

Role of genetics in educational programming. Parents were then asked about the role that genetic diagnosis plays in their child's educational placement or program, and the role that genetic diagnosis should play (for both questions, 1 = not at all; 5 = very much). They were also asked whether the child's teacher was aware of the diagnosis and "who brings information pertaining to [the] child's genetic diagnosis to the educational setting." This last question asked parents to check all that apply from among the following eight people: parent, child's teacher, school psychologist, pediatrician or other medical professional, resource teacher, speech therapist, occupational therapist, and physical therapist.

Results

Current Placement, Services, and Requested Services

As shown in Table 1, no significant differences were found in the educational placements of children in each of the three groups. Across all groups, most children were being educated in either fully or partially integrated settings, with about 40% of each group in special class placements. There were also no differences in satisfaction with current educational placement, F(2, 64) = 1.92, ns. The mean satisfaction rating for parents of children with Down syndrome was 3.33; for Prader-Willi syndrome, the mean was 4.00; and for Williams syndrome, the mean was 3.67. There were no significant between-group differences in the number of hours of each special service children received weekly, and only one between-group difference in the percentages of students who received each service (WS > DS, PWS for Occupational Therapy, see Table 1).

In contrast, parents in the three groups did show some differences in their desire for extra services for their children. Though 90.5% of children with Down syndrome currently receive speech therapy, greater percentages of parents of these children expressed a desire for additional speech therapy than parents in the other two groups, [chi square] (2, N = 65) = 12.91, p < .002. Although 38.1% of children with Williams syndrome currently receive a one-on-one aide in the classroom, parents of children with Williams syndrome significantly more often expressed a desire for more time with a one-on-one aide in the classroom [chi square] (2, N = 65) = 11.62, p < .02 (see Table 2).

Degree to Which Parents Are Informed

Cognitive-Linguistic Profiles. A one-way MANOVA, with the six cognitive-linguistic items serving as dependent variables, showed that parents in the three groups seem to ascribe etiology-based strengths and weaknesses to their respective children, F(12, 112) = 4.51, p < .0001. Follow-up one-way ANOVAs on each of the cognitive-linguistic dimensions suggest that parents of children with Down syndrome recognized their children's weaknesses in expressive language (see Table 3 for a complete list of follow-up ANOVAs).

In addition, a 3 (etiology) x 2 (visual vs. auditory processing) repeated measures ANOVA was performed to determine whether parents knew about the visuospatial and verbal processing profiles of their children with Down syndrome and Williams syndrome. A significant interaction effect was found showing that parents of children with different syndromes rated their children differently in their ability to process verbal versus visual information, F(2, 67) = 6.46, p < .003. Post hoc comparisons showed that parents of children with Down syndrome accurately rated their children as better visual than verbal learners (visual M = 4.20; auditory M = 2.90). In contrast, etiology-based differences in ratings were less consistently found among the other two groups, and parents of children with Williams syndrome rated their children about equal in visual and verbal learning (visual M = 3.65; auditory M = 3.80). However, parents of children with Williams syndrome did give significantly higher ratings to their children on the "auditory learner" scale than either of the other two groups (see Table 3).

A second 3 (etiology) x 2 (sequential versus simultaneous processing) repeated measures ANOVA found no significant interaction effect, F(2, 67) = 1.79, ns. Parents of children with Prader-Willi syndrome did not rate their children as better simultaneous than sequential processors; in fact, these parents tended to consider their children better sequential processors (for the PWS group, sequential M = 4.44; simultaneous M = 2.90).

Behavior Problems. MANOVA results revealed that parents were aware of their child's etiology-related behavior problems, F(6, 124) - 9.12, p < .0001. Compared to parents of children with Down syndrome and Williams syndrome, parents of children with Prader-Willi syndrome rated their children higher on overeating and obsessive-compulsive behavior; similarly, parents of children with Williams syndrome gave higher ratings to their child's being afraid of loud sounds (see Table 3 for follow-up one-way ANOVA analyses).

The Role of Genetic Syndrome in Educational Placement

A one-way ANOVA showed etiology-based differences in how important parents feel their children's genetic syndromes are to their current educational program, F(2, 63) = 3.45, p < .05. Parents of children with Down syndrome rated their children's syndrome as more important for educational purposes (M = 4.09 on a 5-point scale, where 1 = very unsatisfied and 5 = very satisfied) than parents of children with Williams syndrome (M = 2.95) but not Prader-Willi syndrome (M = 3.48). When asked how many different practitioners bring syndrome-related information to the classroom, parents of children with Down syndrome listed significantly more people than the other two groups, F(2, 63) = 16.23, p < .0001. The mean number of people listed by parents of children with Down syndrome was 3.38, whereas parents of children with Prader-Willi syndrome listed 1.52 people and parents of children with Williams syndrome listed 1.25 people, on average. Compared to parents of children with Prader-Willi syndrome or Williams syndrome, parents of children with Down syndrome noted significantly more often that etiology-based information was brought into the school setting by teachers, school psychologists, resource teachers, and speech therapists (see Table 4). The majority of parents of children with Prader-Willi syndrome (52%) and Williams syndrome (66.7%) reported that they were the sole providers of syndrome-related information in the classroom, in contrast with only 9.5% of parents of children with Down syndrome, [chi square] (2, N = 67) = 15.20, p < .001.

As one of the first studies to examine parental knowledge of etiology-related educational issues, this study demonstrates the ways in which etiology-based behavioral research has and has not been made available to those shaping educational programs for children with genetic mental retardation syndromes. Although researchers have established important connections between genetic syndromes and behavioral outcomes, such knowledge has only partially reached parents. The study also sheds light on the way that knowledge about certain syndromes seems "ahead" of knowledge about others.

On the most general level, parents in this study of chronological age-matched children seemed only partially aware of well-established etiology-related behaviors. Although parents of children with Down syndrome seemed aware of their children's strong visual over verbal processing abilities and relative weaknesses in expressive language, parents in the other two groups rated their children less in accord with their etiology-based behaviors. To some extent, parents seemed informed about the more visible features of their child's syndromes: overeating and obsessive-compulsive behaviors in Prader-Willi syndrome, visual processing strength and verbal expression weaknesses in Down syndrome, and musicality in Williams syndrome. Parents were not as aware of some of the more subtle and complex cognitive features associated with their children's syndromes. Parents of children with Prader-Willi syndrome, for example, were not aware of their children's simultaneous processing strengths, and parents of children with Williams syndrome did not report stronger verbal than visual processing abilities in these children.

Even less connection to etiology seems apparent in the supportive services provided for children with these three syndromes. Children with Down syndrome, Prader-Willi syndrome, and Williams syndrome all received similar services--no connections to etiology-related strengths or weaknesses were apparent. For example, even though children with Down syndrome have marked language delays compared with children in the other two groups, no differences were observed in the amounts of speech therapy they received.

At the same time, however, the parent findings must be considered in light of both the behavioral domain and the specific etiology. In terms of behavioral domains, parents in both the Prader-Willi and Williams syndrome groups were aware of their children's troublesome maladaptive behaviors. Parents of children with Prader-Willi syndrome rated their children's overeating and obsessive-compulsive behaviors at much higher levels than did the parents of children with the other two syndromes. Similarly, parents of children with Williams syndrome seemed somewhat aware of their children's sensitivity to loud noises. Such attention to behavior problems, though not present in every instance, was usually present among parents of children in these two groups.

A second qualifier of these findings concerns Down syndrome. Compared to parents of children with Prader-Willi or Williams syndromes, parents of children with Down syndrome possessed more in-depth understandings of their children's etiology-related behaviors. They were aware that their children are better visual than auditory processors, and that these children have relative weaknesses in verbal expression. Even though almost all children with Down syndrome (90.5%) were already receiving speech therapy, a full 80% of such parents desired more speech-language services for their children. Indeed, parents of children with Down syndrome answered all etiology-related items in the predicted ways. In contrast, parents of children with the other two syndromes were primarily informed about their children's maladaptive behaviors but were much less attuned to their child's cognitive-linguistic profiles.

Several reasons might account for this "Down syndrome advantage" in terms of parental knowledge. The first and most obvious explanation concerns the relative understanding of this syndrome by both the general public and researchers. In contrast to both Prader-Willi syndrome and Williams syndrome, Down syndrome is known to the public through TV shows (Life Goes On) and popular books (e.g., Kingsley & Levitz, 1994); the syndrome also has several large and active national and international parent organizations. Even among researchers, Down syndrome is a "known" disorder. For 140 years, researchers have examined many of this disorder's genetic, physical, and medical aspects (Pueschel, 1990); to this day, almost half of all behavioral work featuring any genetic mental retardation disorder includes individuals with Down syndrome as one of its groups (Hodapp, 1996). In addition to being based on fewer studies, the behavioral findings on Prader-Willi syndrome, Williams syndrome, and other less well-known disorders, although accumulating at a rapid rate, date mostly to the late 1980s and 1990s (Dykens et al., 2000).

This general, long-standing awareness of Down syndrome might also explain the findings concerning who brings genetic information into the classroom setting. Compared to Prader-Willi syndrome and Williams syndrome, parents of children with Down syndrome are not the sole etiology-oriented "information-providers" for the education of their children. As shown in Table 4, parents of children with Down syndrome are often joined by their children's teachers, school psychologists, speech therapists, and others in bringing information about Down syndrome into the classroom. In contrast, many parents of children with Williams and Prader-Willi syndromes find themselves the sole providers of syndrome-related information, even though they may not have access to a great deal of information. Indeed, the link remains unclear between how much parents and professionals know about etiology-related behaviors, who brings such knowledge into the classroom setting, and how educational practices change as a result.

As an early exploration of a complex topic, this study also has certain methodological limitations that should be noted. First, the samples were obtained through parent groups and therefore may not reflect the larger populations of families of children with these three syndromes. Particularly with Prader-Willi and Williams syndromes, families connected to the nationwide parent groups may be a uniquely informed subset of parents of children with this syndrome.

A second limitation is that some domains of processing were difficult to describe in lay terms. For example, we described sequential processing as "step-by-step learning" and simultaneous processing as "learning well by being given the big picture." Respondents, however, may have had difficulty rating their children using these approximate definitions. Also, although etiology-based behavioral profiles are found in most children with particular syndromes, individual children undoubtedly varied in the degree to which they expressed the behavioral profiles associated with these three syndromes (Dykens, 1995). Future studies need to link children's performance on various assessments of intellectual and maladaptive behaviors to parent and teacher ratings.

Several additional issues remain to be discussed. First, this article has implicitly adopted an approach that supports Aptitude x Treatment interactions, or ATIs. Thus, we have implicitly argued that children with one or another specific behavior or pattern of behaviors might respond better to one type of treatment versus another. To date, researchers in both general and special education have not always found such interactions.

Given this lack of evidence, some have argued that ATIs should be abandoned as a special education approach (Gresham & Witt, 1997; Lloyd, 1984). In contrast, others have argued that ATI research has suffered from poor conceptualization by researchers and the construction of an ATI "straw man" that has been readily proven ineffective (Speece, 1990). It may be that researchers have not yet developed effective methods for uncovering ATIs, and there may be factors that make existent ATIs difficult to uncover.

A future direction for this line of research is to translate syndrome-based profiles into specific educational practices or guidelines. For example, research is needed on the nature of the relative strength in visuospatial processing in individuals with Down syndrome and how this modal processing strength can be used to improve verbal processing-dependent developmental outcomes, such as language development. Such research could then be used to tailor instructional approaches in weaker domains (i.e., language acquisition) for individuals with Down syndrome and tested for efficacy in classrooms and other special education settings.

This study begins the process of examining the degree to which etiology-related behavioral information is known to parents and used in the educational setting. At this point, the picture seems mixed. Etiology-related behavioral problems seem more salient to parents than cognitive-linguistic strengths and weaknesses. According to parental report, their children's educational services are generally not attuned to etiology-related cognitive-linguistic profiles or behavior problems. And yet, if the example of Down syndrome information is instructive, many people--both parents and professionals--may soon bring etiology-related information to the classroom. Indeed, as behavioral information becomes better known to parents, teachers, and other service providers, more targeted, successful etiology-based instructional accommodations can be developed for children with many different genetic mental retardation disorders.