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: 20.77). 06/2008; 31(3):241-61; discussion 261-320. DOI: 10.1017/S0140525X08004214
Source: PubMed


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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Available from: Christopher Robert Badcock, Jul 31, 2014
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    • "Both Hyper-and HypoToM can lead to errors on standard ToM tasks, but these different strategies would lead to different kinds of error (Frith, 2004). According to the diametric model of the mind and mental illness, all mental disorders can be located along this dimension of ToM ranging from Hypo-to HyperToM (Crespi & Badcock, 2008; Badcock, 2011). It has been hypothesized that individuals with ASD and individuals with psychosis spectrum disorders (PSD) may be located at the extreme ends (Ciaramidaro et al. 2015). "
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    ABSTRACT: Background: Knowledge on the risk mechanisms of psychotic experiences (PE) is still limited. The aim of this population-based study was to explore developmental markers of PE with a particular focus on the specificity of hyper-theory-of-mind (HyperToM) as correlate of PE as opposed to correlate of any mental disorder. Method: We assessed 1630 children from the Copenhagen Child Cohort 2000 regarding PE and HyperToM at the follow-up at 11-12 years. Mental disorders were diagnosed by clinical ratings based on standardized parent-, teacher- and self-reported psychopathology. Logistic regression analyses were performed to test the correlates of PE and HyperToM, and the specificity of correlates of PE v. correlates of any Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) mental disorder. Results: Univariate analyses showed the following correlates of PE: familial psychiatric liability; parental mental illness during early child development; change in family composition; low family income; regulatory problems in infancy; onset of puberty; bullying; concurrent mental disorder; and HyperToM. When estimating the adjusted effects, only low family income, concurrent mental disorder, bullying and HyperToM remained significantly associated with PE. Further analyses of the specificity of these correlates with regard to outcome revealed that HyperToM was the only variable specifically associated with PE without concurrent mental disorder. Finally, HyperToM did not share any of the investigated precursors with PE. Conclusions: HyperToM may have a specific role in the risk trajectories of PE, being specifically associated with PE in preadolescent children, independently of other family and child risk factors associated with PE and overall psychopathology at this age.
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    • "Interactions among conspecifics constitute an important basis for the organization of life and provide many health benefits to social species. Deficits in social behavior are linked to developmental abnormalities in children, such as autism spectrum disorders (ASD), and can also occur later in life as a sign of major psychiatric illnesses such as schizophrenia or major depression (Crespi and Badcock, 2008). "
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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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