Psychotic-like symptoms and positive schizotypy are associated with mixed and ambiguous handedness in an adolescent community sample Neus Barrantes-Vidal a,b,c,d,n,1 , Lizzette Go ´ mez-de-Regil a,e,1 , Blas Navarro f , Jordi Vicens-Vilanova a , Jordi Obiols a , Thomas Kwapil d a Departament de Psicologia Clı ´nica i de la Salut, Facultat de Psicologia, Universitat Aut  onoma de Barcelona, Bellaterra, 08193 Barcelona, Spain b Departament de Salut Mental, Sant Pere Claver—Fundacio ´ Sanit  aria, Vila i Vil  a 16, 08004 Barcelona, Spain c Instituto de Salud Carlos III, Centro de Investigacio ´n Biome´dica en Red de Salud Mental, CIBERSAM, Spain d University of North Carolina at Greensboro, Department of Psychology, P.O. Box 26170, Greensboro, NC 27402-6170, USA e Hospital Regional de Alta Especialidad de la Penı ´nsula de Yucata ´n (HRAEPY), Departamento de Planeacio ´n, Ensen˜anza e Investigacio ´n, Km. 8.5 Carretera Me ´rida-Cholul,Me´rida, Yucata ´n 97134, Me´xico f Departament de Psicobiologia i Metodologia, Facultat de Psicologia, Universitat Aut  onoma de Barcelona, Bellaterra, 08193 Barcelona, Spain article info Article history: Received 27 June 2011 Received in revised form 30 November 2012 Accepted 11 December 2012 Keywords: Psychosis-proneness Schizophrenia Laterality abstract The objective of this study was to replicate the association between atypical handedness and psychosis- proneness in a representative sample of adolescents from the general population. It expands previous studies by (1) analyzing a variety of atypical handedness indexes (left, mixed, ambiguous, and inconsistent), (2) measuring comprehensively the multidimensionality of psychosis-proneness, and (3) analyzing the association of different patterns of atypical handedness with nonclinical dimensions of both trait (schizotypy) and sub-clinical symptom (psychotic-like experiences) levels. Seven hundred and twenty-eight adolescents were assessed for handedness by the 12-item self-report Annett Hand Preference Questionnaire and for psychosis-proneness by the Oxford-Liverpool Inventory of Feelings and Experiences and the Community Assessment of Psychic Experiences scales. Writing-hand alone did not detect associations between laterality and psychosis-proneness. Mixed- rather than left- handedness was related to psychosis-proneness, and this was more evident when analyzing subjects with ambiguous handedness exclusively. When analysis was restricted to subjects with non-ambiguous handedness, strong left-handedness was related to psychosis-proneness. The positive dimension showed a stronger association than the negative one with atypical handedness. Results partially support mixed-handedness as a marker of developmental disorders underlying both atypical later- alization and psychosis-proneness. Among various possible mixed-handedness patterns, inconsistent hand use across primary actions, and for the same action across time, seems particularly related to psychosis-proneness and thus requires further exploration. & 2012 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Schizotypy phenotypes in the general population share etio- pathogenic mechanisms and risk factors with schizophrenia, supporting the notion of psychosis as a continuum ranging from nonclinical to clinical deviance (van Os et al., 2009). The non- clinical psychosis phenotype (i.e., psychosis-proneness) is observed and reliably measured at the level of schizotypic personality features (using trait-like measures) and psychotic- like experiences (using symptom-based measures; Kwapil et al., 1999; Stefanis et al., 2002; Barrantes-Vidal et al., 2009, 2010). A substantial body of work has demonstrated that psychometri- cally assessed schizotypy is associated cross-sectionally with laboratory, interview, cognitive, and biobehavioral measures of schizophrenic symptoms and impairment (Claridge, 1997; Raine, 2006; Blanchard et al., 2011; Kwapil et al., 2012). Furthermore, longitudinal research indicates that psychometric schizotypy is associated with the development of psychosis and schizophrenia- spectrum disorders (e.g., Chapman et al., 1994; Gooding et al., 2005) with effect sizes as large as or larger than in studies of consangui- nity. The study of psychosis-proneness in nonclinical samples allows the analysis of risk factors without the confounding effects of psychosis (e.g., medication, symptom severity, and stigma). An abnormality in cerebral lateralization has long been related to the etiology of schizophrenia (Crow, 1990; Sommer et al., 2001) and more recently of schizotypy (Richardson et al., 1997; Somers et al., 2009). This fits well with the view that schizophrenia is a Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/psychres Psychiatry Research 0165-1781/$ - see front matter & 2012 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.psychres.2012.12.008 n Corresponding author at: Departament de Psicologia Clı ´nica i de la Salut, Facultat de Psicologia, Universitat Aut  onoma de Barcelona, Bellaterra, 08193 Barcelona, Spain. Tel.: þ34 93 581 3864; fax: þ34 93 581 2125. E-mail addresses: neus.barrantes@uab.cat (N. Barrantes-Vidal), gomezderegil@gmail.com (L. Go ´ mez-de-Regil). 1 Shared first authorship. Psychiatry Research 206 (2013) 188–194