Schizotypy: Reflections on the Bridge to Schizophrenia and Obstacles on the Road Ahead to Etiology and Pathogenesis

Abstract

Abundant empirical data, drawn from a variety of methodologies and at different levels of analysis, support a robust connection between schizotypic psychopathology and the underlying liability for schizophrenia. This liability is termed schizotypy and represents a unifying latent construct that gives rise to both psychopathologies. Schizotypy can manifest itself in a variety of forms ranging from flagrant schizophrenia through less conspicuous schizotypic conditions to nearly silent manifestations known as endophenotypes, which can be detected only with properly sensitive technologies. Therein lies the power and research potential of the study of schizotypic psychopathology, namely it offers a window on schizophrenia liability (schizotypy). This window is particularly useful as it provides a view of liability uncontaminated by factors such as deterioration, medication sequelae, and institutionalization effects. However, the major stumbling block in the road ahead for schizotypy research, at all levels of analysis, is the problem of heterogeneity. Heterogeneity is observed across symptom pictures, performance patterns on laboratory tasks, longitudinal course, and, probably, at the level of genetic inputs as well. In order to advance our understanding of schizophrenia, schizotypic psychopathology, and all manner of endophenotypes the issue of heterogeneity must be confronted and resolved in a principled manner. A cautionary discussion of neuroimaging and its utility for advancing our understanding of the etiology and pathogenesis of schizophrenia and related pathologies provides a vantage point from which to view the promise of any one method in terms of resolving power. Finally, a discussion of the highly problematic, yet age-old, problem of rating approaches to measurement in psychopathology research and the value of the counting, ratio-scale approach is highlighted.