Dopaminergic foundations of schizotypy as measured by the German version of the Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE)—a suitable endophenotype of schizophrenia

Personality Psychology and Individual Differences, Department of Psychology, Justus-Liebig-University Giessen Giessen, Germany.
Frontiers in Human Neuroscience (Impact Factor: 2.9). 01/2013; 7:1. DOI: 10.3389/fnhum.2013.00001
Source: PubMed

ABSTRACT The concept of schizotypy or "psychosis proneness" captures individual differences in perceptual, cognitive, and affective experiences that may relate to a range of psychotic disorders. The concept is an important way to assess the contribution of pre-existing psychological and genetically based biological features to the development of illnesses such as schizophrenia (so called endophenotypes). The Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE) is a widely used multi-dimensional measure of the construct and consists of four scales which mirror several groups of psychotic symptoms: Unusual Experiences (UnEx; positive symptoms), Cognitive Disorganization (CogDis; cognitive symptoms), Introvertive Anhedonia (IntAn; negative symptoms), and Impulsive Nonconformity (ImpNon; impulsive and antisocial symptoms). For the purpose of evaluating the suitability of schizotypy as an endophenotype of schizophrenia the current version of the O-LIFE was translated into German: its psychometric properties (including re-test reliability and construct validity) were examined in a large sample (n > 1200) and compared to those of the English original. The German version was both highly reliable and consistent with the original. The study aimed to show that schizotypy as measured by the O-LIFE can indeed be regarded as an endophenotype of schizophrenia in terms of genetic associations regarding relevant dopamine-related candidate polymorphisms of schizotypy [i.e., Val(158)Met-polymorphism of the COMT gene, uVNTR of the MAOA gene, Taq1A-polymorphism of the DRD2 gene, VNTR of the SLC6A3 (DAT) gene]. We also wanted to compare the genetic associations of the O-LIFE to those published using other operationalizations of schizotypy. Our results show a large number of significant associations and borderline-significant trends between the O-LIFE sub-scales and a range of genes, thereby supporting using the O-LIFE in the search for endophenotypic markers.

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    Frontiers in Psychiatry 09/2014; 5:134. DOI:10.3389/fpsyt.2014.00134
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    ABSTRACT: Schizotypy refers to a constellation of personality traits that are believed to mirror the subclinical expression of schizophrenia in the general population. Evidence from pharmacological studies indicates that dopamine (DA) is involved in the etiology of schizophrenia. Based on the assumption of a continuum between schizophrenia and schizotypy, researchers have begun investigating the association between DA and schizotypy using a wide range of methods. In this article, we review published studies on this association from the following areas of work: (1) experimental investigations of the interactive effects of dopaminergic challenges and schizotypy on cognition, motor control, and behavior (2), dopaminergically supported cognitive functions (3), studies of associations between schizotypy and polymorphisms in genes involved in dopaminergic neurotransmission, and (4) molecular imaging studies of the association between schizotypy and markers of the DA system. Together, data from these lines of evidence suggest that DA is important to the expression and experience of schizotypy and associated behavioral biases. An important observation is that the experimental designs, methods, and manipulations used in this research are highly heterogeneous. Future studies are required to replicate individual observations, to enlighten the link between DA and different schizotypy dimensions (positive, negative, cognitive disorganization), and to guide the search for solid DA-sensitive behavioral markers. Such studies are important in order to clarify inconsistencies between studies. More work is also needed to identify differences between dopaminergic alterations in schizotypy compared to the dysfunctions observed in schizophrenia.
    Frontiers in Psychiatry 12/2014; 5:184. DOI:10.3389/fpsyt.2014.00184
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    ABSTRACT: The schizotypy construct focuses attention on the liability to develop schizophrenia-spectrum disorders, yet traditionally, the schizotypy models have put more emphasis on stress-vulnerability interactions rather than developmental dynamics of emerging risk for psychopathology. Indeed, developmental accounts of this emerging personality trait have rarely been explicitly formulated. In this position article, we wish to convey some of the basic developmental tenets of schizotypy, and how they can inform high-risk research. Firstly, we tackle the state vs trait issue to outline the possible relationship between high-risk states and trait schizotypy. Second, we review the evidence suggesting that the consolidation of schizotypy, encompassing its 3 main dimensions, could be considered as a developmental mediator between very early risk factors and transition into high-risk states. Importantly, developmental dynamics between endophenotypes, as well as transactional and epigenetics mechanisms should enter modern conceptualizations of schizotypy. Finally, we present a developmental psychopathology perspective of schizotypy sensitive to both the multifinality and equifinality of schizophrenia-spectrum disorders. We conclude that schizotypy represents a crucial construct in a fully-developmental study of schizophrenia-spectrum disorders. © The Author 2014. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email:
    Schizophrenia Bulletin 12/2014; DOI:10.1093/schbul/sbu175 · 8.61 Impact Factor


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May 27, 2014