Claridge Gordon - Schizotypy: new dimensions

First published 2015
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2015 O. Mason and G. Claridge

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British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library

Library of Congress Cataloging in Publication Data
Schizotypy (Mason)
Schizotypy : new dimensions / edited by Oliver Mason and
Gordon Claridge.
p. ; cm.
Includes bibliographical references and index.
I. Mason, Oliver, 1967- , editor. II. Claridge, Gordon, 1932- , editor.
III. Title.
[DNLM: 1. Schizotypal Personality Disorder. 2. Schizophrenic
Psychology. WM 203]
RC569.5.S36
616.8581dc23
2014046166

ISBN: 978-0-415-72203-2 (hbk)
ISBN: 978-1-315-85856-2 (ebk)

Typeset in ITC New Baskerville Std
by Swales & Willis Ltd, Exeter, Devon, UK

Advances in Mental Health Research series

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Adapting the Tavistock method
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Olivia Sagan

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Research and practice
Edited by Joshua L. Cohen and J. Lauren Johnson with Penelope P. Orr

Schizotypy
New dimensions
Edited by Oliver J. Mason and Gordon Claridge

Contents

OLIVER J. MASON AND GORDON CLARIDGE

THOMAS R. KWAPIL AND CHARLOTTE A. CHUN

CHRISTINE MOHR AND ULRICH ETTINGER

PHILIP GRANT

GINA M. GRIMSHAW AND LAURA KRANZ

MARTIN DEBBAN

TJASA VELIKONJA, OLIVER J. MASON AND HELEN L. FISHER

TAMARA SHEINBAUM AND NEUS BARRANTES-VIDAL

EMMA BARKUS

CHRISTINA DANIEL AND OLIVER J. MASON

CHARLIE HERIOT-MAITLAND AND EMMANUELLE PETERS

JO HODGEKINS

NICOLA J. HOLT

GORDON CLARIDGE

Part I
Measurement, brain and biology

Part III
Consequences and outcomes

7
Mechanisms mediating the pathway from environmental adversity to psychosis proneness

Tamara Sheinbaum and Neus Barrantes-Vidal

Introduction

A fast-growing field of research investigating the effects of psychosocial adversity on the brain is challenging the view that the endophenotypic abnormalities found in schizotypy and schizotypal personality disorder (SPD) only derive from genetic and biological insults for instance, early life maltreatment impairs brain structure and physiology (e.g. Teicher, Anderson, Ohashi, & Polcari, 2013). Notably, animal models (e.g. of maternal separation) suggest that these exposures cause brain and behavioural phenotypes that are analagous to those observed in individuals with schizophrenia (Brown, 2011).

Epidemiological research has recently shown an association of psychosocial factors both at macro (i.e. social) and micro (i.e. personal) environmental levels with clinical and non-clinical psychosis, particularly for the dimension of reality distortion (reviews in Bentall & Fernyhough, 2008; Brown, 2011). Some studies are conflicting, but there is an increasing consensus that psychosocial adversity is not merely a trigger of a genetically based psychosis proneness, but rather a co-participating factor in the make-up of the diathesis to psychosis. Velikonja, Mason, & Fisher ( in this volume) have reviewed in depth the relation of schizotypy with maltreatment, parental loss and bullying. In this chapter, we will first provide a brief overview of the array of candidate psychosocial factors that have been associated with schizotypy, and then focus on the mediating mechanisms that have received most attention in accounting for the adversityschizotypy connection.

Macro-environmental risk factors

Urbanicity

An increasing body of evidence indicates that early exposure to an urban environment is associated with both subclinical and clinical psychosis (Krabbendam & van Os, 2005). Studies have demonstrated a dose-response effect of urbanicity on psychotic-like experiences (PLEs) (van Os, Hanssen, Bijl, & Vollebergh, 2001) and that the persistence of PLEs is greater among those living in an urban as opposed to a rural area (Spauwen, Krabbendam, Lieb, Wittchen, & van Os, 2006).

Poverty

Poverty seems to be more strongly related to psychosis than to other psychiatric conditions (Read, 2010). A Swiss general population survey that assessed all DSM-IV (American Psychiatric Association, 2000) personality disorders found that poverty was uniquely associated with SPD ratings (Hengartner, Ajdacic-Gross, Rodgers, Mller, & Rssler, 2013). Additionally, other general population studies have provided evidence that socio-economic disadvantage (variously defined) is associated with a greater likelihood of reporting PLEs (e.g. Saha, Scott, Varghese, & McGrath, 2013).

Minority status

Evidence suggests that both first- and second-generation immigrants have an increased risk for developing psychosis (Bourque, van der Ven, & Malla, 2011), and that migrant status is associated with a greater prevalence of PLEs (van Os, Linscott, Myin-Germeys, Delespaul, & Krabbendam, 2009). According to van Os (2012), several pieces of evidence (including the fact that the risk for psychosis persists into the second generation and is also found in ethnic minorities without recent history of migration) suggest that it is not migration in itself that elevates psychosis proneness, but rather certain features of the greater social context in the host country, particularly the situation of being in a minority group position. In this respect, research examining the rates of psychotic disorders among ethnic minority individuals has shown that the rates increase as the proportion of the own ethnic group in the neighbourhood of residence decreases (e.g. Boydell et al., 2001). Although studies focusing on ethnic density and psychosis proneness are scarce, a nationally representative study in the UK indicated that, as a whole, ethnic minorities living in a lower own-group density neighbourhood were more likely to endorse PLEs (Das-Munshi et al., 2012).

Micro-environmental risk factors

Family environment

There is evidence linking family environment variables, such as parental communication deviance and expressed emotion, with the risk and course of psychotic disorders. Certain aspects of the family milieu have been associated with PLEs. For example, children with psychotic symptoms are more likely to have mothers with negative expressed emotion, but not decreased warmth (Polanczyk et al., 2010), and individuals high on social anhedonia report less cohesive and more conflictive family environments than controls (Blanchard, Collins, Aghevli, Leung, & Cohen, 2011).