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There has been much attention directed toward the identification of specific characteristics associated with the Down syndrome behavioural phenotype. Researchers have identified patterns of behavioural characteristics including strengths in the areas of social functioning^[1,2] and weaknesses in such areas as communication^[3,4], short term memory^[5], and cognition (e.g., problem solving^[6]). As others have proposed^[7,8], this knowledge, combined with research demonstrating effective intervention strategies, enables us to explore matching evidence based intervention procedures with specific behavioural characteristics to further advance the development of individuals with Down syndrome.

One area of concern with regard to the development of individuals with Down syndrome is the likelihood of challenging behaviours. It is believed the presence of several characteristics associated with the Down syndrome behavioural phenotype directly increase the likelihood of individuals with Down syndrome exhibiting challenging behaviour. Specifically, the increased desire to escape tasks, impaired communication skills, and possibly, enhanced social motivation, are likely to contribute to an individual with Down syndrome developing challenging behaviours. Fortunately, there is a compendium of evidenced based strategies regarding the assessment and intervention of such behaviours. Over the past several decades, our knowledge has grown exponentially in relation to assessment, prevention, and amelioration of challenging behaviours in individuals with developmental disabilities. In this paper, we present several recommendations matching evidence based intervention strategies with specific challenges faced by children with Down syndrome. These recommendations have the potential to improve outcomes for individuals with Down syndrome.

Increased likelihood of challenging behaviour

One characteristic long associated with individuals with Down syndrome is their tendency to be stubborn^[9,10]. Additionally, several studies specifically examining the presence of challenging behaviour in individuals with Down syndrome indicate challenging behaviours take many forms such as noncompliance, compulsions, and talking to oneself^[11-14]. Additionally, behaviours such as those associated with anxiety, depression and withdrawal have been noted to increase with age^[12,15]. As we seek to identify interventions to ameliorate these challenging behaviours, it is important to consider early developing characteristics, those that have been identified as part of the Down syndrome behavioural phenotype, that are likely to contribute to the presence of more significant challenging behaviours in individuals with Down syndrome. Attention to them may prevent the development of more significant challenging behaviour as the child matures.

One characteristic of young children with Down syndrome is their increased likelihood of engaging in behaviour to avoid learning tasks. As demonstrated by the work of Wishart and her colleagues, such "opting" out of learning opportunities is apparent within the first year of life^[16,17,18]. Thus, the youngest of children with Down syndrome are engaging in specific behaviours that interfere with skill development. Within the toddler years, these opting out behaviours often take the form of "cute" party trick behaviours to "get out" of situations, specifically learning tasks. Such behaviours appear to persist throughout childhood and adolescence preventing children with Down syndrome from accessing important learning opportunities.

Researchers have also described individuals with Down syndrome as having strengths in social functioning^[1]. This may be the result of children with Down syndrome being motivated to engage in social interactions with others. However, this increased desire to engage in social interactions may also result in an increase in socially motivated challenging behaviour (e.g., throwing food items during mealtime so Mom immediately comes over to the child and picks up the food items, coaxing the child to continue eating). Additionally, children with Down syndrome demonstrate weaker skills in reading other's emotions^[19]. Therefore, the child with Down syndrome may in fact be rewarded by receiving any type of attention regardless of whether that attention would be considered positive (e.g., verbal praise, smile) or negative in nature (e.g., reprimand, stern look).

Another characteristic associated with the Down syndrome behavioural phenotype that influences the likelihood of challenging behaviour is the presence of communication impairments associated with Down syndrome. Specifically, the impairments in expressive communication are well documented^[3,4,20] and are apparent quite early in development. For example, requesting behaviours, that emerge in the first year of life in typically developing children, are impaired in children with Down syndrome (e.g., refs 6,21,22,23). During the later years, speech intelligibility is also quite poor in individuals with Down syndrome^[24]. Impaired communication not only results in reduced social interactions, but also likely increases the probability of challenging behaviours emitted due to the lack of more appropriate communicative responses^[25,26].

These characteristics, all related to the Down syndrome behavioural phenotype, affect the developing behavioural repertoires of individuals with Down syndrome. In addition, these characteristics can be exacerbated by biological factors associated with Down syndrome^[27]. For example, illness and sleep disorders (which occur with higher incidence in individuals with Down syndrome) are both likely to have an extensive effect on engagement in challenging behaviours. Thus, specific behaviours and impairments, emerging at a very early age, compounded by the presence of biological factors, are likely to result not only in the development of challenging behaviours during the toddler years, but the maintenance of these behaviours throughout childhood. Such behaviours also not only interfere with the acquisition of skills, but, in many communities, preclude individuals with Down syndrome from opportunities with typical peers within educational, community, and employment settings. In light of the negative impact challenging behaviours can have, attention to the identification of effective interventions that correspond to the characteristic behavioural deficits associated with the Down syndrome behavioural phenotype, beginning at the earliest stages of development, is essential.

Evidence based interventions

One of the greatest contributions to the quality of life of individuals with developmental disabilities has been the development of functional behaviour assessment procedures and implementation of positive behaviour support strategies^[28]. These technologies have enhanced quality of life, creating access to community schools, housing, recreation, and employment for many individuals with developmental disabilities. In previous work, we^[27] provided an overview of the functional assessment process^[29] and identified studies demonstrating the effectiveness of behavioural intervention strategies to address specific behavioural challenges often seen in individuals with Down syndrome. Thus, empirically demonstrated strategies to address challenging behaviour in individuals with Down syndrome do exist. With the identification of an early emerging Down syndrome behavioural phenotype, it is now possible to explore the matching of intervention strategies to address these characteristic behaviours before they become significant challenging behaviours that disrupt skill acquisition^[30].

Preventing challenging behaviours from entering the repertoire of young children with Down syndrome

Based on our extensive review of the literature addressing challenging behaviours in individuals with developmental disabilities and our own intervention research (as well as our clinical work in both home and school settings), we suggest several recommendations that can prevent or minimise the emergence of challenging behaviours within the repertoire of individuals with Down syndrome.

Recommendation 1: Provide caregivers with information regarding identifying and intervening upon potentially challenging behaviours

"Challenging behaviours" are quite common and transient in typically developing children. For example, it is not uncommon for a typically developing child to tantrum, act aggressively toward a peer, or engage in an idiosyncratic behaviour that he/she finds stimulating (e.g., staring at a spinning ceiling fan). However, it is when these behaviours interfere with social relationships, cause injury to self or others, or prevent the acquisition of new skills^[26] that intervention is warranted. Unfortunately, it is not always readily obvious when the child has "crossed the line" between typical behaviours and those that are, or will soon develop into, problematic behaviours. Thus, it is essential that caregivers (both family members and early interventionists) be informed of the behaviours that are characteristic of young children with Down syndrome and are likely to become problematic over time.

One means of identifying such behaviours is to gain an understanding of the functions that the behaviours serve for a particular child. Thus, caregivers should be empowered with the understanding that behaviours emitted by children serve a function (e.g., to escape an activity, to obtain an item) and the manner in which those behaviours are consequated will result in either their increase or decrease over time. There is much empirical support for this notion, as analysis of the intervention literature has determined that when intervention is based upon a functional assessment, the effectiveness of intervention procedures is improved^[31]. Thus, given strategies to determine the function of behaviours, caregivers can then be advised to intervene upon these specific behaviours in a timely fashion. This urgency is not because we are certain that all of the behaviours will become problematic with time, but because, at the early stages of development, one cannot predict which behaviours will become problematic for an individual child. Additionally, addressing challenging behaviours when the child is young prevents a history of engagement in the behaviour which in turn increases the likelihood of amelioration. In our experience when all caregivers are active members of the child's team and receive ongoing training, as described above, the typical challenges that arise are easier to ameliorate and thus do not become significant over time. Therefore, it is essential to provide caregivers with training to prepare them to address the presence of early escape behaviours (e.g., throwing materials, turning away from challenging tasks), self-stimulatory behaviours (e.g., teeth grinding, hand waving, rocking), and inappropriate attention seeking behaviours (e.g., approaching a forbidden area).

Recommendation 2: Develop strategies to address early escape behaviours

As demonstrated by Wishart, very young children with Down syndrome have a propensity to opt out of learning situations^[8,17]. Such refusal to engage in tasks results in inconsistent performance over time^[18,32]. When these behaviours appear during the toddler and preschool years, they can easily be interpreted as "typical" childhood behaviours. However, the young child who consistently escapes from difficult tasks during the toddler years can become the young child or elementary school student who also seeks to escape rather than to tackle the task at hand and now has a long history of successfully doing so. Thus, using strategies that prevent the occurrence of escape behaviour, from a very early age, may minimise the negative effects that are likely to present themselves at a later point in time developing into a pattern of escape motivated behaviour.

There are several antecedent strategies that can be used to prevent the occurrence of escape behaviour. For example, task difficulty can be manipulated so that the task is less challenging and less likely to result in challenging behaviour. Once the child with Down syndrome is performing the task at that level, the difficulty level of the task can be gradually increased. Additionally, specific prompts can be delivered to ensure successful engagement in the task (e.g., errorless learning strategies). Consequence strategies involving reinforcement can also be utilised to increase the value of engaging in the task. For example, we have had tremendous success using token systems with toddlers with Down syndrome^[32]. Laminated photos of preferred cartoon characters are attached to a strip of cardboard each time the target response is performed. When a pre-determined number of responses occur (determined by individual child performance), a reinforcing item/activity is delivered (e.g., singing a song, playing a game, accessing a toy). A combination of these strategies (antecedent and consequence strategies) has led to decreased escape behaviour, increased engagement in target responses, and increased attention during instructional/therapeutic opportunities in children with Down syndrome^[33].

Recommendation 3: Teach requesting behaviours

One communication impairment that appears early in development in children with Down syndrome is that of requesting^[6,21,22,23]. Seen in typical infants during the latter half of the first year of life, requesting takes multiple forms including the use of eye gaze, gesture (e.g., pointing), and vocalisation to regulate the behaviour of another (e.g., to access an object or activity). Although requesting behaviours are particularly important as they are directly related to later communicative and cognitive competence (e.g., refs 6,22,23,34,35), there are only a handful of studies that specifically targeted requesting skills for intervention^[36,37]. Keeping in mind that the lack of effective communication skills is likely to result in the onset of challenging behaviours^[25], intervention is warranted to provide the individual with Down syndrome an appropriate means of communicating.

We have taught communication skills, including requesting, with intensive instruction^[38] involving repeated opportunities presented in close temporal proximity, with little or no engagement in alternate activities between opportunities, utilising specific prompting procedures and high rates of reinforcement^[39,40]. We taught young children with Down syndrome (between 10 and 26 months of age) requesting responses consisting of eye gaze and vocalisation (e.g., an open mouth sound), with some of the children being taught to emit the sound "mmm" as an approximation of more^[39,41]. The response taught involved a request for continuation of a preferred activity with an object (e.g., shaking and then tickling with a small stuffed toy). Intervention was then applied to teach requests involving assistance (described by Fidler et al., as instrumental requests^[6]). Our findings suggest that this intervention was effective in addressing requesting deficits. In addition there is a need to systematically teach requesting in a variety of situations to ensure children with Down syndrome possess requesting skills commensurate with typical development.

Requesting may be a "pivotal" skill for children with Down syndrome. Pivotal skills are those that, once acquired, result in collateral improvements in related skill areas^[42]. There may be several skill areas, those specifically impaired in young children with Down syndrome (part of the behavioural phenotype), including short term memory and imitation, that are likely to operate as pivotal skills. Children with Down syndrome show strong visual motor imitation skills, but impaired vocal imitation skills^[43,44]. Imitation has been linked to expressive language^[45,46]; and play skills^[45]. Therefore vocal imitation may in fact be a pivotal skills and, fortunately, there exists empirically validated interventions to address vocal imitation skills in young children with developmental disabilities^[47]. However, systematic applications of vocal imitation interventions taking place with young children with Down syndrome are rare.

Recently, we assessed the imitation skills of six children with Down syndrome (2 years old) and found that none of the children demonstrated vocal imitation^[41]. We taught caregivers to use intensive instruction (the same type of instruction we used to teach requesting: multiple closely placed teaching opportunities, using systematic prompting procedures and the delivery of predetermined consequences). The children were first taught motor imitation (e.g., tap head, tap table, clap hands) and then vocal imitation (e.g., "aah" "ba" "mmm"). Not only did each child acquire the vocal skills targeted for imitation, but after having acquired between 3 and 4 specific sounds in vocal imitation, participants demonstrated generalised imitation. That is, they imitated or attempted to imitate any vocalisation asked of them. This allowed for the prompting of verbal approximations using verbal models within naturally occurring situations (e.g., "mmm" for more, "hup" for help, and "em" for an approximation of Emily, one of the participants' names). Thus, establishing early vocal imitation skills allowed for the prompting of other communication behaviours across multiple environments.

With respect to preventing challenging behaviours, gains in early imitation and communication skills allow caregivers to prompt more appropriate responses in situations where a child may be likely to engage in a challenging behaviour to request attention or access to a tangible, in addition to situations in which he/she desires to escape (e.g., say "done" to indicate the desire to terminate an activity). Doing so prior to the occurrence of the challenging behaviour allows reinforcement to be delivered as a consequence for appropriate behaviour, rather than for engagement in challenging behaviour.

Recommendation 4: Decrease the extent to which children engage in self-stimulatory behaviours

Self-stimulatory behaviours are behaviours emitted by an individual that result in automatic reinforcement. Therefore, the individual engages in the behaviour because it either feels good (i.e., he/she is obtaining some type of pleasure from the act) or the individual is trying to escape internal stimuli (e.g., a young child bangs his ear to escape the pain of an ear infection). There is an increased likelihood of self-stimulatory behaviour associated with developmental disabilities, and, although not a defining characteristic of Down syndrome, there are many individuals with Down syndrome who engage in some form of self-stimulatory behaviour (e.g., tongue clicking, rocking, placing hands in mouth, teeth grinding). These behaviours can be particularly disruptive to learning opportunities and participation in community settings, as well as stigmatising with peers.

To illustrate, a 12 month old child with Down syndrome whose intervention programme was supervised by the first author, tended to rock back and forth. At first, caregivers thought he was dancing, but then noticed that the behaviour occurred quite often, when the child was alone as well as in the presence of others, when music was playing and when there was no music. This suggested that rocking was self-stimulatory in nature. A simple interruption procedure involving gently holding the child's shoulders until the rocking stopped, followed by prompting an appropriate social behaviour (e.g., clapping hands, throwing a kiss, or catching a ball) and reinforcement for appropriate behaviour resulted in a substantial decrease in the behaviour. There is strong evidence for the use of these types of interventions to decrease self-stimulatory behaviours in individuals with developmental disabilities^[48,49]. The early application of interventions to decrease self-stimulatory behaviours ensures that children with Down syndrome are not missing valuable learning opportunities and/or being socially ostracised as a result of engaging in self-stimulatory behaviour.

Conclusion

The presence of challenging behaviour that interferes with the acquisition of new skills, stigmatises the child, and prevents access to community environments, is likely to be manifested during the early stages of development, thus negatively changing the course of development in the child with Down syndrome. We hypothesise that adherence to the recommendations outlined above with systematic instruction, delivered by caregivers (i.e., family members, teachers, related service providers), it is possible to not only prevent behavioural deficits from entering their repertoire, but to facilitate the acquisition of a variety of early developing skills in very young children with Down syndrome. We further propose the following questions for future research:

1. What is the best way to empower families with the knowledge they need to identify and address (via evidence based interventions) early developing behaviours that have the potential to become challenging over time?
2. Does empowering caregivers with such knowledge prevent specific behaviours seen in young children with Down syndrome that are associated with the Down syndrome behavioural phenotype (e.g., opting out of learning tasks)?
3. Does early attention to these behaviours result in a decrease in the likelihood that individuals with Down syndrome engage in challenging behaviour throughout their life time?
4. What collateral changes result from the matching of interventions with behavioural phenotype characteristics? For example, does establishing the systematic instruction of imitation skills enhance communication skills (e.g., requesting) and in turn, will the early enhancement of communication skills result in changes, not only in decreasing significant challenging behaviours, but improving cognitive performance (e.g., problem solving)?

In most communities, children with Down syndrome immediately receive early intervention services for the primary purpose of ensuring that the child will in fact learn as many skills as possible to enjoy a productive lifestyle. This goal may be realised for more children with Down syndrome if we are able to improve the effectiveness of these intervention services. As research documents the specific characteristics of the Down syndrome behavioural phenotype, we are faced with the task of drawing on empirically demonstrated intervention procedures to address those skill weaknesses/impairments. Matching intervention procedures with characteristic deficits has the potential to improve the efficiency and effectiveness of intervention efforts, possibly resulting in collateral changes in other areas of impairment in individuals with Down syndrome, thus preventing a host of negative outcomes.

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Kathleen M Feeley is Assistant Professor, Department Special Education and Literacy,

Emily A Jones is Assistant Professor, Department of Psychology, both at C.W. Post Campus of Long Island University, 720 Northern Blvd, Brookville, New York 11548

Correspondence to Kathleen M Feeley • e-mail: Kathleen.feeley@liu.edu

 

Paper prepared from presentations and discussions at the Down Syndrome Research Directions Symposium 2007, Portsmouth, UK. The symposium was hosted by Down Syndrome Education International in association with the Anna and John J Sie Foundation, Denver. Major sponsors also included the Down Syndrome Foundation of Orange County, California and the National Down Syndrome Society of the USA. Information about the symposium can be found at http://www.dseinternational.org/research-directions/

 

doi:10.3104/reviews.2076

Received: 10 October 2007; Accepted: 17 October 2007; Published online 2 July 2008