The contribution of novel brain imaging techniques to understanding the neurobiology of mental retardation and developmental disabilities

Studying the biological mechanisms underlying mental retardation and developmental disabilities (MR/DD) is a very complex task. This is due to the wide heterogeneity of etiologies and pathways that lead to MR/DD. Breakthroughs in genetics and molecular biology and the development of sophisticated brain imaging techniques during the last decades have facilitated the emergence of a field called Behavioral Neurogenetics. Behavioral Neurogenetics focuses on studying genetic diseases with known etiologies that are manifested by unique cognitive and behavioral phenotypes. In this review, we describe the principles of magnetic resonance imaging (MRI) techniques, including structural MRI, functional MRI, and diffusion tensor imaging (DTI), and how they are implemented in the study of Williams (WS), velocardiofacial (VCFS), and fragile X (FXS) syndromes. From WS we learn that dorsal stream abnormalities can be associated with visuospatial deficits; VCFS is a model for exploring the molecular and brain pathways that lead to psychiatric disorders for which subjects with MR/DD are at increased risk; and finally, findings from multimodal imaging techniques show that aberrant frontal-striatal connections are implicated in the executive function and attentional deficits of subjects with FXS. By deciphering the molecular pathways and brain structure and function associated with cognitive deficits, we will gain a better understanding of the pathophysiology of MR/DD, which will eventually make possible more specific treatments for this population.     

Goodness-of-fit ethic for informed consent to research involving adults with mental retardation and developmental disabilities

This article reviews current theory and research on informed consent policies for adults with mental retardation within a relational ethics framework that re-conceptualizes consent vulnerability in terms of the goodness-of-fit between participant decisional capacities and the specific consent context. Conceptualizing informed consent competence as a product of the relationship between person and consent context shifts assessment of decisional capacity away from an exclusive focus on a research participant's cognitive deficiencies to (a) an examination of those aspects of the consent setting that are creating or exacerbating consent vulnerability and (b) consideration of how the setting can be modified to produce a consent process that best reflects and protects the hopes, values, concerns, and welfare of adults with developmental disabilities.     

Quality of life of adults with mental retardation/developmental disabilities who live with family

In this paper, we review the literature related to the quality of life of adults with mental retardation/developmental disabilities (MR/DD) who live at home with their families. We examine the nature of the relationships between adults with MR/DD and their parents and siblings, the social worlds of adults with MR/DD, age-related functional and health issues that affect their quality of life, the range of services and supports provided to them, and familial efforts to plan for their continued well-being when parental care is no longer viable. Individual characteristics associated with these dimensions and/or more compromised quality of life profiles are identified. The paper concludes with recommendations for expanded research on the quality of life of adults with MR/DD who live in the parental home, a topic which has received markedly less attention than the quality of life of adults who live in publicly supported residential settings. MRDD Research Reviews 7:105-114, 2001.     

Theoretical perspectives on language and communication problems in mental retardation and developmental disabilities

We argue that researchers interested in language and communication problems in mental retardation or any other developmental disorder should view such problems as emerging within the broader context of the behavioral profile, or phenotype, associated with a particular genetic condition. This will require understanding the direct and indirect effects of genes on the development of language and communication and thereby an understanding of the complex relations that exist between language and other dimensions of psychological and behavioral functioning as well as an understanding of the environments in which the developing person acts and is acted upon. We believe that the dominant model for understanding language and communication problems--the nativist approach, which emphasizes the child's innate capacity for acquiring language and characterizes language as consisting of a set of context-free deterministic rules that operate on abstract representations--is inconsistent with an emphasis on indirect genetic effects. We review recent evidence that undermines the nativist approach--evidence concerning the initial state of the language-learning child, the role of environmental input, the competence-performance distinction, and modularity. In place of nativism, we argue for Emergentism, which is a model in which language is seen to emerge from the interaction between the child's biological abilities to map statistical properties of the language input into a distributed representation and the characteristics of the language learning environment and for the purpose of engaging in real-time, meaningful language use.     

Living circumstances of children and adults with mental retardation or developmental disabilities in the United States, Canada, England and Wales, and Australia

The purpose of this article was to collate evidence to describe where people with mental retardation or developmental disabilities live in five developed countries: United States, Canada, England, Wales, and Australia. Family homes are important dwelling places for people with mental retardation. They are the home of the great majority of children with mental retardation and a considerable proportion of adults with mental retardation. The likelihood of placement outside the family home increases with adulthood and progressively as people age. Adults with mental retardation live in a wide variety of settings, with formal residential provision frequently dependent on the arrangements that the authorities responsible for providing service support have chosen to make. There has been a considerable move away from accommodating people in large segregated and geographically isolated institutions in the countries considered. However, the current range of accommodation includes much with a distinctively different character to the homes where other citizens live. Many people still live in larger groups than would be ordinarily found in typical homes and this may necessitate departure from the architectural norm. In all of the countries considered, there has been a recent trend towards small community settings, compatible with typical housing architecture. This appears furthest advanced in the U.S. but is discernible elsewhere. Availability of residential services at a national level varies between 100 and 155 places per 100,000 total population. Regional variation within countries is even greater. In no case is the national availability considered adequate to meet the demand arising from changing need or expectations. MRDD Research Reviews 7:115-121, 2001. (c) 2001 Wiley-Liss, Inc.     

Applications of gene targeting technology to mental retardation and developmental disability research

The human and mouse genome projects elucidated the sequence and position map of innumerous genes expressed in the central nervous system (CNS), advancing our ability to manipulate these sequences and create models to investigate regulation of gene expression and function. In this article, we reviewed gene targeting methodologies with emphasis on applications to CNS development and neurodevelopmental disorders.     

Evaluating backward chaining methods on vocational tasks by adults with developmental disabilities

Backward chains are widely used to teach complex skills to individuals with developmental disabilities. Implementation of chaining procedures may vary regarding untaught steps and there is little to guide practitioners in the selection of chaining procedures. Moreover, there is a dearth of research evaluating effectiveness and efficiency of procedural variations of behavior chains. The purpose of this study was to extend previous research by evaluating the effectiveness, efficiency, and preference for four procedural variations (i.e., teacher‐completion, participant‐completion, no‐completion, and a control condition) of backward chains across vocational tasks with adults with developmental disabilities. Although procedural variations effectively established vocational skills, the participant‐completion procedure (in which the instructor implemented a least‐to‐most prompt hierarchy during all untrained steps in the chain) was the most efficacious backward chaining procedural variation and efficient in terms of sessions to mastery. The no‐completion procedure (in which the instructor completed all untrained steps in the chain out of view of the participant) was least efficient across trials, sessions, errors, and total duration to mastery. One participant preferred the no‐completion condition while the other two participants showed an initial preference for the teacher‐completion condition that changed to preference for the no‐completion condition. Vocational skills maintained 1‐ and 4‐weeks postmastery. Stakeholders rated goals, procedures, and outcomes as socially valid.     

Predicting the relative efficacy of three presentation methods for assessing preferences of persons with developmental disabilities

Choices were presented to 9 individuals with developmental disabilities using a two-choice format. Each pair of items, selected based on prior preference assessment, was presented to each participant in three conditions (actual items, pictures of the items, and spoken-name presentation) using a reversal design. The evaluation was conducted using food items, and was then repeated using nonfood items. The participants were also given a test to measure their skills on discrimination tasks ranging in difficulty from simple to conditional discriminations. The participants' abilities to make consistent choices with food and nonfood items were predicted, with 94% accuracy, by their discrimination skills. The findings suggest that presentation methods can affect the accuracy of a choice assessment, and that the systematic assessment of basic discrimination skills can be used to predict the effectiveness of different presentation methods in this population.     

Life skills instruction for children with developmental disabilities

The Preschool Life Skills program is an intervention package designed to teach functional skills to prevent problem behavior in typically developing children. The purpose of the current study was to evaluate the effects of the instructional package (renamed “Life Skills”) with children with developmental disabilities. The program involved teaching 12 life skills to nine participants across four instructional units. The units were instruction following, functional communication, tolerance of denial and delay, and friendship skills. Teachers provided instruction through a three-tiered instructional approach, starting with class-wide instruction followed by small group and one-to-one instruction as necessary. We extended previous research by using visual prompts during all three tiers and progressively increasing intertrial intervals during one-to-one instruction. Results indicated that the intervention led to skill acquisition with all nine participants. The skills maintained 4 weeks after instruction ended.     

Mental retardation genes in drosophila: New approaches to understanding and treating developmental brain disorders

Drosophila melanogaster is emerging as a valuable genetic model system for the study of mental retardation (MR). MR genes are remarkably similar between humans and fruit flies. Cognitive behavioral assays can detect reductions in learning and memory in flies with mutations in MR genes. Neuroanatomical methods, including some at single-neuron resolution, are helping to reveal the cellular bases of faulty brain development caused by MR gene mutations. Drosophila fragile X mental retardation 1 (dfmr1) is the fly counterpart of the human gene whose malfunction causes fragile X syndrome. Research on the fly gene is leading the field in molecular mechanisms of the gene product's biological function and in pharmacological rescue of brain and behavioral phenotypes. Future work holds the promise of using genetic pathway analysis and primary neuronal culture methods in Drosophila as tools for drug discovery for a wide range of MR and related disorders.     

Co-occurrence of developmental disabilities with birth defects

This article begins with a discussion of the concepts of comorbidity and co-occurrence of diseases and health conditions. These concepts are then applied to the literature on the population-based prevalence of developmental disabilities and birth defects. Most of the existing literature focuses on co-occurrence and obtains data from both clinical and administrative sources. Developmental disabilities occur more frequently in children with multiple, rather than with isolated, birth defects. More research, with more sophisticated study designs, will be necessary to further elucidate the contributions of birth defects to the etiology of developmental disabilities, control for other risk factors, and to identify strategies for prevention and intervention services.     

A multidisciplinary treatment for encopresis in children with developmental disabilities

Achieving continence of one's bowel movements is a key step in development and failure to do so leads to many negative consequences. Treatments for encopresis appearing in the literature have employed behavioral strategies; medications such as suppositories, laxatives, or enemas; and in some studies a combination of these approaches. To date, attempts to extend successful treatments for encopresis in typically developing children to those with developmental disabilities have been limited. The current study included three participants diagnosed with developmental disabilities who had a history of encopresis. None of the participants had a continent bowel movement under baseline conditions. Continent bowel movements increased during treatment that included the addition of suppositories to elicit continent bowel movements. Two participants began having independent continent bowel movements (i.e., without requiring suppositories) and medication was successfully faded out for the remaining participant. Treatment took between 13 and 21 days.     

Psychodynamic counselling with parents of children with developmental disabilities

A joint treatment of parents and child can be the treatment of choice when dealing with developmental disabilities. In our clinical experience, we have observed that psychoanalytically oriented support (developmental guidance), which involves the child and the parents together, answers the needs and addresses the difficult dynamics that are characteristic of developmental disabilities.     

Expanding the utility of behavioral momentum for youth with developmental disabilities

Non‐compliance with requests in educational or therapeutic settings interferes with teaching and learning. Recent studies indicate that the probability of compliance can be increased when short sequences of requests with a high probability of compliance are followed by a request less likely to be followed by compliance. The high probability command sequence (HPCS) consists of requests that produce compliance rates of 80% or more. For some individuals with severe disabilities it is difficult to find sufficient number of requests that result in 80% compliance. This study assessed the effects of two levels of high probability request sequences on compliance with subsequent low probability requests. The three participants (ages 7, 11, and 20) met the diagnostic criteria for autism and/or severe to profound mental retardation. Results showed that both high (>80% compliance) and medium (50–70% compliance) request sequences produced increases in compliance to subsequent requests that had produced low compliance rates (<40%) during baseline. No systematic differences were observed between high and medium probability sequences. Copyright © 2000 John Wiley & Sons, Ltd.     

Improving accepting and giving compliments with individuals with developmental disabilities

Individuals with developmental disabilities, such as autism spectrum disorder, typically exhibit conversation skill deficits, with two prevailing deficits including giving and accepting compliments. The current study used an individualized approach to assess and teach accepting and giving compliments specific to performance, possession, and appearance with three adolescents and young adults with developmental disabilities. We taught these skills using behavioral skills training and prompting during conversations utilizing a multiple-baseline design across participants. We also observed generalization and treatment extension of the participants' skills in conversations with adults not associated with teaching and in the absence of any teaching procedures. The results support the efficacy of the procedures used toward improving giving and accepting compliments within the context of a conversation. We discuss considerations to improve the social acceptability of and refinements to the teaching procedures and acquired skills.     

Quality care in residential placement for children and youth with developmental disabilities

There is a growing concern for quality care in residential placements outside of the natural family for children and youth with developmental disabilities. Ideally, children with developmental disabilities should remain with their natural parent or parents of parents with appropriate supports until the age when children typically leave home. In reality, parents of children and youth with development disabilities are not always able or willing to care for their children at home, and alternate residential placements must be found. This paper will discuss some of the issues surrounding the provision of quality care in out-of-home residential placements for children and youth with developmental disabilities.     

Replications and extensions in arousal assessment for sex offenders with developmental disabilities

Three adult male sex offenders with developmental disabilities participated in phallometric assessments that involved repeated measures of arousal when exposed to various stimuli. Arousal assessment outcomes were similar to those obtained by Reyes et al. (2006). Additional data-analysis methods provided further information about sexual preferences, thus replicating and extending previous research. The results provide preliminary data for establishing a preference gradient by age. Implications for the use of repeated measures and preference gradients in arousal assessments are discussed.