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The aim of this paper is to provide an overview of the dominant approaches used to explain causes of challenging behaviour.

This paper is the second in a two‐part series. It presents the causes of challenging behaviour according to the three theoretical approaches that have dominated the literature: applied behaviour analysis; biological factors; and psychiatric disorders.

It is apparent that the causes of challenging behaviour are likely to be complex and involve multiple factors. The approaches that have dominated the literature focus on single causes and do not explore possible interactions between various causes. Given the shortcomings of existing approaches, a fourth approach, the biopsychosocial model, is proposed as an alternative model to explain the causes of challenging behaviour.

This paper is the most recent of only a few providing an overview of the various approaches that seek to explain the causes of challenging behaviour.

The purpose of this paper is to establish the value of clinical genetic diagnostics in the lives of people with an intellectual disability (ID), their families, and their primary and professional caregivers. It has been shown that psychologists are more likely to make use of the opportunities offered by clinical genetic diagnostics if they have seen the psychological benefits in their own practice. Moreover, this paper aims to promote the practice of informing people with ID, their families, and other caregivers regarding the current technological advances in genetic diagnostics, thereby allowing these patients to decide for themselves whether to utilise these opportunities.

The authors report four case studies in which the psychosocial value to each patient is pivotal.

In these four cases, it is clear the medical model can augment the social model by providing an interpretation of its meaningfulness in the lives of the people concerned.

Case studies alone can have limited scientific significance. This approach examining the significance of clinical genetic diagnosis should be studied further in larger groups.

It is hoped that psychologists and other professional caregivers will become enthused about the value of clinical genetic diagnostics and will choose to discuss the option of referral for clinical genetic diagnostics with their patients more often.

People with an ID who are seeking mental health care, and their caregivers, should be given the opportunity to take part in the decision regarding whether to use clinical genetic diagnostics, which may even have a destigmatising effect.

Quality of life may improve for people with an ID seeking mental healthcare and for their caregivers as well by opening up discussion regarding the opportunities presented by clinical genetic diagnostics. The fact that people are able to make their own choices based on their own considerations can have a destigmatising effect.

Tuberous sclerosis complex (TSC) is a genetic disorder with a high prevalence of autism spectrum disorder (ASD), yet no single genetic, neurological or neurophysiological risk marker is necessary or sufficient to increase risk for ASD. This paper aims to discuss the utility of adopting a developmental perspective.

The increasing number of TSC infants presenting with abnormalities prenatally provides a unique opportunity to study risk pathways to ASD from birth. Here, the authors review findings to date that support the investigation of infants with TSC to further our understanding of typical and atypical development.

Evidence has accumulated from studies of infants at familial risk for ASD (“baby siblings”) to suggest that early markers of ASD are present in the first year of life. The early waves of prospective studies of infants with TSC indicate dynamic changes in developmental trajectories to ASD and are likely to provide insight into cascading effects of brain “insult” early in development. Emerging evidence of phenotypic and biological homology between syndromic and idiopathic cases of ASD supports the notion of a convergence of risk factors on a final common pathway in ASD.

The delineation of brain-based biomarkers of risk, prediction and treatment response in TSC will be critical in aiding the development of targeted intervention and prevention strategies for those infants at high risk of poorer developmental outcomes.

This paper seeks to discuss the complexity of the relationship between genotype and phenotype and highlight the importance of a greater understanding of behavioural phenotypes in genetic syndromes. The aim is to explore the developmental trajectory of the behavioural phenotypes as individuals emerge from childhood into adulthood and beyond.

Information was gathered from a search of the relevant literature over the past 20 years using Medline and PsycINFO databases in May 2010 as well as information published in textbooks on this matter.

The outcomes were considered under five areas of functioning: cognition, communication, behaviour, social functioning and propensity to psychiatric illnesses. The research thus far suggests that outcomes in behavioural phenotypes in adults are extremely variable. Individual predictions are difficult to make. However, some trends do emerge.

Findings of particular interest are the rates of attention deficit hyperactivity disorder and autism spectrum conditions and how these change over the developmental trajectory. The paper highlights the need for further research in this area and discusses the need to view behavioural phenotypes as a continuum across the lifespan.

The behavioral phenotype of fragile X syndrome (FXS) and intellectual disability (ID) proposed by Hagerman et al. (2009) was primarily based on data from male children and teens. The purpose of this study was to promote a better understanding of how this condition manifests in adults.

A total of 18 men of FXS were paired with men with Down syndrome on the basis of age and level of ID. A screening checklist was created on the basis of existing scales and the Hagerman et al. (2009) behavioral phenotype and completed by care providers.

Five of the 12 features of the phenotype were significantly more present among men with FXS than in men with Down syndrome.

This study provides partial confirmation for Hagerman et al.’s (2009) behavioral phenotype of FXS among men with moderate ID and identified some traits that warrant further investigation.

Heritability studies attempt to estimate the contribution of genes (vs. environments) to variation in phenotypes (or outcomes of interest) in a given population at a given time. This chapter scrutinizes heritability studies of adverse health phenotypes, emphasizing flaws that have become more glaring in light of recent advances in the life sciences and manifest most visibly in epigenetics.

Drawing on a diverse body of research and critical scholarship, this chapter examines the veracity of methodological and conceptual assumptions of heritability studies.

The chapter argues that heritability studies are futile for two reasons: (1) heritability studies suffer from serious methodological flaws with the overall effect of making estimates inaccurate and likely biased toward inflated heritability, and, more importantly (2) the conceptual (biological) model on which heritability studies depend – that of identifiably separate effects of genes versus the environment on phenotype variance – is unsound. As discussed, contemporary bioscientific work indicates that genes and environments are enmeshed in a complex (bidirectional, interactional), dynamic relationship that defies any attempt to demarcate separate contributions to phenotype variance. Thus, heritability studies attempt the biologically impossible. The emerging research on the importance of microbiota is also discussed, including how the commensal relationship between microbial and human cells further stymies heritability studies.

Understandably, few sociologists have the time or interest to be informed about the methodological and theoretical underpinnings of heritability studies or to keep pace with the incredible advances in genetics and epigenetics over the last several years. The present chapter aims to provide interested scholars with information about heritability and heritability estimates of adverse health outcomes in light of recent advances in the biosciences.

The area of behavioural phenotype research and related clinical practice is now recognised as one of high relevance to all practitioners who help people with learning disabilities, whatever their age. Knowledge continues to accumulate rapidly regarding aspects pertaining to aetiology, likely developmental, emotional and behavioural challenges, useful multidisciplinary interventions and supports and long‐term prognosis. This paper reviews the concept, its history and recent developments, focusing on those aspects which are of particular importance to clinical and other care and support professionals and their clients. There is a continuing need for widespread dissemination of the large body of relevant information, and its application to practice in order to maximise benefits for people with learning disabilities and their families.

Cornelia de Lange syndrome (CdLS) is a congenital disorder characterized by distinctive facial features, growth retardation, limb abnormalities, intellectual disability, and behavioral problems. Cornelia de Lange syndrome is associated with abnormalities on chromosomes 5, 10 and X. Heterozygous point mutations in three genes (NIPBL, SMC3 and SMC1A), are responsible for approximately 50-60% of CdLS cases. CdLS is characterized by autistic features, notably excessive repetitive behaviors and expressive language deficits. The prevalence of autism spectrum disorder (ASD) symptomatology is comparatively high in CdLS. However, the profile and developmental trajectories of these ASD characteristics are potentially different to those observed in individuals with idiopathic ASD. A significantly higher prevalence of self-injury are evident in CdLS. Self-injury was associated with repetitive and impulsive behavior. This study describes the behavioral phenotype of four children with Cornelia de Lange syndrome and ASDs and rehabilitative intervention that must be implemented.

This article focuses on the consequences of having FraX‐E, the rare but well recognised variant of fragile X syndrome. The authors provide some background on the condition and report on recent research and evidence. Three case reports are outlined and the specific behavioural aspects of the syndrome are considered. The authors argue that it is important that the behavioural phenotype for FraX‐E is clearly identified and defined in order to give those with the condition relevant psychological and educational support in the future.

Political scientists have taken up behavior genetics (BG) at a momentous time in the science of genetics. Momentous, because the science of genetics is undergoing a paradigm shift [Petronis, A. (2010). Epigenetics as a unifying principle in the aetiology of complex traits and diseases. Nature, 465(7299), 721–727]. This shifting paradigm poses a significant challenge to both the prevailing methodologies of behavior genetics – twin, family, adoption studies – and one of the most noteworthy findings to emerge from such studies, that is, which we can call the principle of minimal parental effects. This is the supposition that the effect of the shared parental rearing environment on the behavioral phenotypes of offspring is statistically equivalent to zero (Plomin & Daniels, 1987). It is not uncommon nowadays to find twin, adoption, and family studies utilized in the study of political behavior (e.g., Alford, J., Funk, C. L., & Hibbing, J. R. (2005). Are political orientations genetically transmitted? American Political Science Review, 99(2), 153–167.); likewise, the principle of minimal parental effects is frequently invoked in such studies (e.g., Mondak, J. J., Hibbing, M. V., Canache, D., Seligson, M. A., & Anderson, M. A. (2010). Personality and civic engagement: An integrative framework for the study of trait effects on political behavior. American Political Science Review, 104(1), 85–110.). As we shall see, the challenge comes from recent discoveries in genetics that are radically transforming our understanding of the genome and its relationship to environment.