A disturbed sense of self in the psychosis prodrome: Linking phenomenology and neurobiology

Abstract

Interest in the early phase of psychotic disorders has risen dramatically in recent years. Neurobiological investigations have focused specifically on identifying brain changes associated with the onset of psychosis. The link between these neurobiological findings and the complex phenomenology of the early psychosis period is not well understood. In this article, we re-cast some of these observations, primarily from neuroimaging studies, in the context of phenomenological models of “the self” and disturbance thereof in psychotic illness. Specifically, we argue that disturbance of the basic or minimal self (“ipseity”), as articulated in phenomenological literature, may be associated with abnormalities in midline cortical structures as observed in neuroimaging studies of pre-onset and early psychotic patients. These findings are discussed with regards to current ideas on the neural basis of self-referential mental activity, including the notion of a putative “default-mode” of brain function, and its relation to distinguishing between self- and other-generated stimuli. Further empirical work examining the relationship between neurobiological and phenomenological variables may be of value in identifying risk markers for psychosis onset.

Introduction

Recent years have witnessed an increased interest in the early phase of schizophrenia and other psychotic disorders, including the pre-onset or prodromal period. This focus has been guided by the view that intervening clinically at this point, when the disorder is not yet entrenched, may improve the longer-term outcome of patients or even prevent illness onset (Yung et al., 1996, Yung et al., 2003). Researching the early phase of psychotic disorder is also generally believed to provide a clearer picture of pathophysiological mechanisms at play, before the effects of advanced illness stages cloud the clinical picture (Klosterkötter et al., 2001, Parnas, 2000, Yung et al., 2004a). A substantial amount of theoretical and empirical work indicates that phenomenological anomalies, particularly those reflecting a basic self-disturbance, feature prominently during the psychosis prodrome and may be the core disturbance at work in the emergence of schizophrenia-spectrum disorders (McGhie and Chapman, 1961, McGorry et al., 1987, Møller and Husby, 2000, Parnas, 2000, Parnas, 2003; Parnas and Handest, 2003, Parnas et al., 2003; Parnas et al., 1998).

Neurobiological studies, assisted largely by developments in structural and functional magnetic resonance imaging (MRI) techniques, have begun to map brain changes that occur before, during, and after the development of frank psychotic disorder. This work has indicated that alterations in both brain structure and function are apparent in pre-psychotic individuals (Lawrie et al., 2008, Wood et al., 2008), that some of these changes are correlated with patients’ cognitive difficulties or symptomatology, and that they may progress with transition to frank psychosis (Fornito et al., 2008c; Garner et al., 2005, Job et al., 2005, Pantelis et al., 2003). Ultimately, it is hoped that such findings may be useful as biological markers of risk for transition to psychotic disorder, and/or help to elucidate pathophysiological changes that occur as psychotic illness develops. However, neurobiological studies have not yet considered how brain alterations during the onset of psychosis may relate to the phenomenological disturbances, particularly those related to self-experience, that feature prominently during this period (Parnas, 2000, Parnas, 2003; Parnas and Handest, 2003, Parnas et al., 2003; Parnas et al., 1998). The converging evidence from recent work on the neural correlates of self-related mental activity (Gusnard et al., 2001, Northoff et al., 2006) has therefore prompted us to re-consider the neuroimaging evidence base in early psychotic disorders in the context of phenomenological models of psychosis.

This paper focuses on recent evidence that points towards alterations of cortical midline structures as underlying a disrupted sense of self in prodromal patients. While this discussion is essentially speculative, we believe that it is through this integrative framework that a coherent and testable model of psychotic disorders can be developed. To this end, we begin with a brief overview of current phenomenological theories of the early stages of psychosis, arguing that a disturbance of the basic sense of self, sometimes referred to as “ipseity” disturbance, may account for many of the key phenomenological changes that occur during the prodrome. We then consider how such disturbances might relate to altered function of cortical midline structures of the brain, and briefly review the provisional evidence for such abnormalities in early psychosis.