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Crespi B, Badcock C. Psychosis and autism as diametrical disorders of the social brain. Behav Brain Sci 31: 241-261

Department of Biosciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
Behavioral and Brain Sciences (Impact Factor: 14.96). 06/2008; 31(3):241-61; discussion 261-320. DOI: 10.1017/S0140525X08004214
Source: PubMed

ABSTRACT Autistic-spectrum conditions and psychotic-spectrum conditions (mainly schizophrenia, bipolar disorder, and major depression) represent two major suites of disorders of human cognition, affect, and behavior that involve altered development and function of the social brain. We describe evidence that a large set of phenotypic traits exhibit diametrically opposite phenotypes in autistic-spectrum versus psychotic-spectrum conditions, with a focus on schizophrenia. This suite of traits is inter-correlated, in that autism involves a general pattern of constrained overgrowth, whereas schizophrenia involves undergrowth. These disorders also exhibit diametric patterns for traits related to social brain development, including aspects of gaze, agency, social cognition, local versus global processing, language, and behavior. Social cognition is thus underdeveloped in autistic-spectrum conditions and hyper-developed on the psychotic spectrum.;>We propose and evaluate a novel hypothesis that may help to explain these diametric phenotypes: that the development of these two sets of conditions is mediated in part by alterations of genomic imprinting. Evidence regarding the genetic, physiological, neurological, and psychological underpinnings of psychotic-spectrum conditions supports the hypothesis that the etiologies of these conditions involve biases towards increased relative effects from imprinted genes with maternal expression, which engender a general pattern of undergrowth. By contrast, autistic-spectrum conditions appear to involve increased relative bias towards effects of paternally expressed genes, which mediate overgrowth. This hypothesis provides a simple yet comprehensive theory, grounded in evolutionary biology and genetics, for understanding the causes and phenotypes of autistic-spectrum and psychotic-spectrum conditions.

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    • "This could also help to establish the validity of the assumption that there is a continuum of social ability relating to the number and severity of autistic traits, regardless of a clinical threshold. Social difficulties such as problems in forming or maintaining interpersonal relationships or engaging in inappropriate behaviour are often central to the everyday struggles that individuals with ASD face (Troisi 2008; Crespi and Badcock 2008). In order to design effective interventions, such as social skill training, it is important to have a detailed understanding of how individuals' symptoms may interact with the environment and disrupt everyday functioning. "
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    ABSTRACT: Measuring autistic traits in the general population has proven sensitive for examining cognition. The present study extended this to pro-social behaviour, investigating the influence of expectations to help others. A novel task describing characters in need of help was administered to students scoring high versus low on the Autism-Spectrum Quotient. Scenarios had two variants, describing either a 'clear-cut' or 'ambiguous' social rule. Participants with high versus low autistic traits were less pro-social and sympathetic overall towards the characters. The groups' ratings of char-acters' expectations were comparable, but those with high autistic traits provided more rule-based rationales in the clear-cut condition. This pattern of relatively intact knowledge in the context of reduced pro-social behaviour has implications for social skill training programmes.
    Journal of Autism and Developmental Disorders 02/2015; 45(8). DOI:10.1007/s10803-015-2393-x · 3.34 Impact Factor
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    • "Later it was realised that there were very significant differences. Crespi and Badcock (2008) point out that autism shows a general pattern " of constrained overgrowth, whereas schizophrenia involves undergrowth " . They also point out that " these disorders exhibit diametrical patterns for traits related to social brain development, including aspects of gaze, agency, social cognition, local versus global processing, language and behaviour " . "
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    • "Later it was realised that there were very significant differences. Crespi and Badcock (2008) point out that autism shows a general pattern " of constrained overgrowth, whereas schizophrenia involves undergrowth " . They also point out that " these disorders exhibit diametrical patterns for traits related to social brain development, including aspects of gaze, agency, social cognition, local versus global processing, language and behaviour " . "
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    ABSTRACT: In the target article, Crespi & Badcock (C&B) propose a novel hypothesis based on observations that a large set of phenotypic traits exhibit diametrically opposite phenotypes in autism-spectrum versus psychotic-spectrum conditions. They propose that development of these conditions is mediated in part by alterations in “genomic imprinting.” This hypothesis is based on the model of the Prader-Willi and Angelman syndromes. The authors have produced a masterful discussion of the differences between psychosis and autism. Of course, another article could be written on the similarities.
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