Schizotypy and clinical symptoms, cognitive function, and quality of life in individuals with a psychotic disorder
Introduction
Schizotypy encompasses a collection of atypical or maladaptive personality traits, odd behaviors, unconventional beliefs, and unusual cognitive and perceptual experiences. Several definitions, approaches, and structures of schizotypy have been proposed in connection with theories of psychotic disorders, primarily schizophrenia. For example, Meehl conceptualized schizotypy as a dichotomous, taxometric construct that represented genetic risk for schizophrenia (“schizogene”) which, when combined with additional genetic potentiators and deleterious life experiences, leads to manifest psychosis (Meehl, 1962). Meehl's and similar models, such as Rado's, are based largely on observations that unaffected relatives of probands exhibit unusual personality characteristics and cognitive deficits similar to those observed in schizophrenia (Rado, 1956a, Rado, 1956b, Rado, 1953). Alternatively, some have posited that the expression of schizotypal characteristics varies along a continuum in the general population which is anchored at the extreme end by schizotypal personality disorder and psychosis (Linscott and Van, 2010, Allardyce et al., 2007, Kwapil et al., 2008, Kwapil et al., 2013). The dimensional approach is supported in large part by individual differences in schizotypy in the normal population and evidence that schizotypal traits correlate with many neurobiological abnormalities observed in schizophrenia, including deficits in cognition, sensorimotor gating, and perception, neurological soft signs, and elevated dopamine function (Ettinger et al., 2014, Woodward et al., 2011).
Surprisingly, relatively little is known about the expression of schizotypy in individuals with a psychotic disorder, despite the fact that models of schizotypy, regardless of type, make several testable predictions. First, if schizotypal personality traits represent stable vulnerability markers, then they should be elevated in individuals with a psychotic disorder and only weakly related to clinical symptoms, especially positive symptoms, which wax and wane over time. Horan et al. (2008) tested this hypothesis in a sample of first-episode patients examined longitudinally. Consistent with a stable vulnerability indicator, physical anhedonia was consistently elevated in schizophrenia and varied little with clinical state. Patients also exhibited consistently higher levels of perceptual aberrations and magical ideation; although they co-varied to some extent with clinical state over time. While informative, this investigation was limited to just schizophrenia patients and did not include additional important measures of schizotypy, such as social anhedonia (Horan et al., 2007, Horan et al., 2008).
A second outstanding question is the specificity of schizotypy to schizophrenia spectrum disorders. Schizotypy has been studied almost exclusively in the context of schizophrenia and is usually considered a latent risk factor specific to schizophrenia (Kwapil, 1998, Lenzenweger and Loranger, 1989a, Lyons et al., 1995). However, there is evidence that some aspects of schizotypy are elevated in individuals with psychotic bipolar disorder and their unaffected relatives (Schurhoff et al., 2005, Etain et al., 2007, Schurhoff et al., 2003, Chapman et al., 1994). Consistent with a latent vulnerability to psychosis more broadly, unaffected relatives of psychotic bipolar patients demonstrate elevated levels of disorganization (Schurhoff et al., 2005). However, in contrast to schizophrenia, physical anhedonia is not elevated in probands with psychotic bipolar disorder and their unaffected family members (Etain et al., 2007, Schurhoff et al., 2003). Similarly, the absence of significant elevations in unaffected family members suggests that among psychosis patients, perceptual aberrations may also be specific to schizophrenia (Lenzenweger and Loranger, 1989a). However, this hypothesis has not been tested.
Finally, the associations between elevated schizotypy, cognitive impairment, and psychosocial functioning in healthy subjects and unaffected family members implies that schizotypy will also correlate with these measures in psychosis patients (Cochrane et al., 2012, Delawalla et al., 2006, Cohen and Davis, 2009). While cognitive impairment and limitations in psychosocial functioning are core features of psychosis, the link between these factors and schizotypy has not been investigated in patients.
To test these predictions, we: 1) compared schizotypal personality traits between healthy individuals and patients with a psychotic disorder and examined the extent to which clinical symptoms overlap with schizotypy; 2) compared schizotypal personality traits between schizophrenia spectrum disorders and bipolar disorder with psychotic features; and 3) examined the relationship between schizotypy, cognitive function, and quality of life in individuals with a psychotic disorder.
Section snippets
Participants
68 individuals with a psychotic disorder (i.e., schizophrenia spectrum disorders, bipolar disorder with psychotic features) and 59 healthy subjects were included in this investigation. Study participants were drawn from a repository of clinical and cognitive data collected on individuals with a primary psychotic disorder and healthy subjects recruited at the Vanderbilt University Department of Psychiatry. The study was approved by the Vanderbilt University Institutional Review Board. All study
Results
Demographic data, schizotypy, and neuropsychological test scores along with clinical variables (i.e., duration of illness, PANSS scores) and quality of life data for healthy subjects and psychosis patients are presented in Table 1.
Discussion
The expression of schizotypy in psychotic disorders has received surprisingly little attention despite the theoretical importance of this construct to psychosis. Consistent with the idea that schizotypy represents stable, trait vulnerability for psychosis, we found that clinical symptoms, which vary markedly over time, are only weakly correlated with schizotypy, if at all. All four measures of schizotypy exhibited minimal to moderate correlations with PANSS scores; no clinical symptom,
Role of funding source
This research was supported by the Jack Martin, M.D., Research Professorship (awarded to NDW). The funding source did not have any role in designing the study; collection, analysis, or interpretation of the data; writing the manuscript; or in the decision to submit the manuscript for publication.
Contributors
Authors EB and NDW conceived and designed the research reported on, analyzed the data, and co-wrote the final draft of the manuscript. Author NDW provided funding for the project.
Conflict of interest
No commercial support was received for this manuscript and the authors have no conflicts of interest to report.
Acknowledgments
This research was supported by the Jack Martin, M.D., Research Professorship (held by NDW). The authors would like to thank Kristan Armstrong for her assistance with recruiting subjects to participate in this study. The authors are indebted to the individuals who participated in the study.
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