The validity of Psychosis Proneness Scales as vulnerability indicators in recent-onset schizophrenia patients

Abstract

The Psychosis Proneness Scales developed by the Chapmans and colleagues (Chapman et al., 1995) are widely used to identify nonpatient individuals who are hypothesized to possess heightened vulnerability to schizophrenia and related psychopathology. Yet surprisingly little is known about whether schizophrenia patients themselves show abnormalities on these scales across different clinical states, as would be expected for vulnerability indicators. Scores on four of the Psychosis Proneness Scales were evaluated at three assessment points over a 15-month period in healthy controls (n = 54) and in recent-onset schizophrenia patients (n = 72) who experienced symptom fluctuations across assessments. Patients showed steady elevations on the Physical Anhedonia Scale across time and clinical state, consistent with a stable vulnerability indicator. Patients had higher scores on the Perceptual Aberration and Magical Ideation Scales than controls throughout the followup period but scores also changed across clinical states, consistent with a mediating vulnerability indicator. Patients had higher scores on the Impulsive Non-Conformity Scale than controls only during a psychotic state, reflecting an episode indicator. The longitudinal characteristics of these scales in people who are actually diagnosed with schizophrenia provide key evidence for the validity of three commonly used psychometric indicators of vulnerability to psychosis.

Attributional Style and Persecutory Delusions. Evidence for an Event Independent and State Specific External-Personal Attribution Bias for Social Situations

“…The use of a questionnaire measure, in form of the Paranoia Checklist to assess vulnerability to psychosis appears justifiable because attenuated subthreshold psychotic symptoms have been found to be risk factors, emerging before first episodes (Horan et al 2008) and are frequently used as a low level criterion in high-risk studies (Yung et al 2003).…”

Ten-year stability of self-reported schizotypal personality features in patients with psychosis and their healthy siblings

“…Therefore, while schizotypy has come to imply a multidimensional neurodevelopmental and psychopathological vulnerability to schizophrenia, schizotypal personality disorder reflects a nosological category of an Axis II diagnosis within the schizophrenia spectrum disorders (Kwapil and Barrantes-Vidal, 2012). Assuming that schizotypal personality disorder might represent not only a categorical diagnostic realm but also a key multidimensional psychopathological construct, schizotypal personality features may be potential vulnerability indicators for schizophrenia and psychosis (Horan et al, 2008). In this regard, several studies have provided interesting data on schizotypal phenomenology complex relationship with psychosis.…”

“…Following Nuechterlein and Dawson (1984) a valid and reliable candidate indicator of vulnerability to psychotic disorders should show evidence of a clear abnormality as compared to the general population, and that the abnormality itself be an enduring feature regardless of patients clinical status. In addition, the pattern of variation in severity of the abnormality in relation to the level of variation in symptoms over the course of the psychotic illness is essential to differentiate between stable, mediating and episoderelated vulnerability markers (independent, partially dependent and dependent on the acute symptomatology, respectively) (Horan et al, 2008).…”

“…This approach has been used with the Chapman's and colleagues Psychosis Proneness Scales to clarify the extent to which their psychometric vulnerability indicators (positive and negative schizotypy) represent state or trait phenomena (Horan et al, 2008). Moreover, there are few studies on schizotypal personality symptoms that include patients with schizophrenia.…”

Affective processing in positive schizotypy: Loose control of social-emotional information

“…Positive schizotypy refers to traits such as odd beliefs and perceptual disturbances that are similar to positive symptoms in schizophrenia, however, these symptoms are not as profound as those found in individuals with schizophrenia (Meehl, 1962;Raine, 2006). Several authors supported the notion that psychometric measures of schizotypy including the positive symptoms scale of the Schizotypal Personality Questionnaire (SPQ; Raine, 1991) indicate vulnerability to schizophrenia and related psychopathology (Barrantes-Vidal et al, 2013;Chapman, Chapman, Kwapil, Eckblad, & Zinser, 1994;Gooding, Tallent, & Matts, 2005;Horan, Reise, Subotnik, Ventura, & Nuechterlein, 2008;Lenzenweger & Loranger, 1989;Vollema, Sitskoorn, Apples, & Kahn, 2002). Research with individuals at risk avoids many confounds associated with chronic schizophrenia such as effects of medication, institutionalization, and changes related to illness duration, and helps identify traits that may be part of the liability to the disorder (Phillips & Seidman, 2008).…”