Early psychopathological features in Spanish adolescents

Schizotypal experiences and depressive symptoms are quite common among adolescents, and have been considered as risk markers for schizophrenia-spectrum and mood disorders. The main goal of the present study was to analyze the relationship between schizotypal experiences and depressive symptoms in a community sample of non-clinical adolescents. The sample comprised a total of 1653 participants, 794 male (48%), with an average age of 15.94 years (SD = 1.23). Results showed that schizotypal traits and depressive symptoms were closely related at a subclinical level. Canonical correlation analysis indicated that the two sets of variables shared approximately 48% of the variance. The study of the dimensionality underlying the subscales of the self-reports revealed the presence of three components, namely: Depressive, Anhedonia and Reality Distortion. These results are convergent with previous studies conducted in both clinical and non-clinical samples, indicating overlap between schizotypal experiences and depressive symptoms.

Schizotypy and pathological personality profile in siblings of patients with psychosis

Schizotypy has been proposed to be the expression of the genetic vulnerability to schizophrenia. Schizotypal features have been associated with personality dimensions found in patients with psychosis. In this study, we compared the Dimensional Assessment of Personality Pathology - Basic Questionnaire (DAPP-BQ) scores of patients with psychosis, siblings scoring higher on schizotypy (SSHS), and siblings scoring lower (SSLS). The SSHSs displayed a DAPP-BQ profile characterized by high scores in the dimensions of affective lability, anxiousness, submissiveness, social avoidance, identity problems, oppositionality, narcissism, and restricted expression, distinguishing them from the SSLS. Due to these dimensions, SSHSs are more similar to the patients' DAPP-BQ profile. The results suggest that this pathological personality profile might contribute to increase the risk of developing psychosis in siblings who have more schizotypal features.

Evidence that familial liability for psychosis is expressed as differential sensitivity to cannabis: an analysis of patient-sibling and sibling-control pairs

CONTEXT

Individual differences in cannabis sensitivity may be associated with genetic risk for psychotic disorder.

OBJECTIVES

To demonstrate and replicate, using 2 conceptually different genetic epidemiological designs, that (familial) liability to psychosis is associated with sensitivity to cannabis.

DESIGN, SETTING, AND PARTICIPANTS

Sibling-control and cross-sibling comparisons using samples of patients with a psychotic disorder (n = 1120), their siblings (n = 1057), and community controls (n = 590) in the Netherlands and Flanders.

MAIN OUTCOME MEASURES

Positive and negative schizotypy using the Structured Interview for Schizotypy-Revised (for siblings and controls) and self-reported positive and negative psychotic experiences using the Community Assessment of Psychic Experiences (for siblings and patients). Cannabis use was assessed as current use (by urinalysis) and lifetime frequency of use (by Composite International Diagnostic Interview).

RESULTS

In the sibling-control comparison, siblings displayed more than 15 times greater sensitivity to positive schizotypy associated with particularly current cannabis use by urinalysis (adjusted B = 0.197, P < .001) than controls (adjusted B = 0.013, P = .86) (P interaction = .04) and a similar difference in sensitivity to its effect on negative schizotypy (siblings: adjusted B = 0.120, P < .001; controls: B = -0.008, P = .87; P interaction = .03). Similarly, siblings exposed to cannabis resembled their patient relative nearly 10 times more closely in the positive psychotic dimension of the Community Assessment of Psychic Experiences (adjusted B = 0.278, P < .001) compared with nonexposed siblings (adjusted B = 0.025, P = .12) (P interaction < .001). No significant effect was apparent for the Community Assessment of Psychic Experiences negative domain, although the association was directionally similar (2 times more resemblance; P interaction = .17). Cross-sibling, cross-trait analyses suggested that the mechanism underlying these findings was moderation (familial risk increasing sensitivity to cannabis) rather than mediation (familial risk increasing use of cannabis).

CONCLUSIONS

Genetic risk for psychotic disorder may be expressed in part as sensitivity to the psychotomimetic effect of cannabis. Cannabis use may synergistically combine with preexisting psychosis liability to cause positive and negative symptoms of psychosis.

Personality and schizophrenia: psychobiological model and its relationship with comorbidity

Personality interacts with psychosocial variables, psychopathology and coping strategies of patients with schizophrenia. Psychobiological model of personality is important for schizophrenia as temperament dimensions, except dimension Persistence, have been associated with different neurotransmitter systems. Comorbidity of psychiatric and somatic disorders and syndromes is generally associated with dimensions high Harm avoidance and low Self-directedness. Variations in other dimensions may also be important. High Harm Avoidance may represent state vulnerability marker for various psychiatric disorders and is associated with appearance of comorbidity in schizophrenia. High Self-directedness may be protective factor for development of various psychiatric as well somatic comorbidity states.

Emotional and behavioural antecedents of young adults who screen positive for non-affective psychosis: a 21-year birth cohort study

BACKGROUND

Birth cohort studies have shown that individuals who develop non-affective psychoses display subtle deviations in behaviour during childhood and adolescence. We had the opportunity to examine the widely used Child Behavior Checklist (CBCL) and the Youth Self-Report (YSR) to explore the antecedents of non-affective psychosis.

METHOD

Based on a birth cohort of 3801 young adults, psychopathology was assessed at years 5 and 14 using the CBCL and/or the YSR. Screen-positive non-affective psychosis (SP-NAP) was assessed at year 21 by using the Composite International Diagnostic Interview (CIDI) or a self-report checklist. The association between childhood symptoms and SP-NAP was examined using logistic regression.

RESULTS

Of the cohort, 60 subjects were classified as SP-NAP. In males, SP-NAP was associated with higher scores: (a) on year 5 CBCL 'Total', 'Aggression' and 'Social, Attention and Thought' scores; (b) on year 14 CBCL 'Social', 'Attention' and 'Delinquency' scores, and (c) YSR 'Total' and many YSR subscores. These associations were less clear for females. Hallucinations at year 14 were associated with SP-NAP for both sexes. Boys with high 'Total' scores at both years 5 and 14 were at greatest risk of SP-NAP (a 5-fold risk), followed by boys and girls whose 'Social, Attention and Thought' scores either increased or remained high from years 5 to 14 (3- to 13-fold risk).

CONCLUSIONS

Individuals who screen positive for non-affective psychosis show increased psychopathology during childhood and adolescence. The psychopathological trajectory of children who go on to develop schizophrenia anticipates the heterogeneity associated with the full clinical syndrome.

Self-reported childhood trauma correlates with schizotypal measures in schizophrenia but not bipolar pedigrees

BACKGROUND

Strong evidence supports the association between childhood trauma and psychotic disorders. In two different high-risk populations, we looked for a correlation between the magnitude of schizotypal dimensions and the importance of self-reported childhood trauma.

METHOD

A sample of 138 unaffected first-degree relatives was recruited (67 relatives of schizophrenic probands and 71 relatives of bipolar probands). The relationship between schizotypal dimensions and childhood trauma scores was analyzed by partial correlations.

RESULTS

A positive correlation was found between childhood trauma scores and total schizotypal scores in first-degree relatives of schizophrenic subjects but not in first-degree relatives of bipolar probands. This correlation was primarily due to a strong association with the positive dimension of schizotypy.

CONCLUSIONS

The significant correlation between childhood trauma and schizotypal dimensions in subjects at high genetic risk for schizophrenia suggests that susceptibility genes for schizophrenia may interact with childhood trauma to induce the emergence of schizotypal dimensions, mainly positive psychotic features.

[Confirmatory factor analysis of schizotypal personality traits in university students]

OBJECTIVE

Investigating the factor structure of schizotypal traits in normal population is important to describe the clinical phenotypes associated with susceptibility to schizophrenia. Schizotypal Personality Questionnaire (SPQ) is a commonly used self-rated measure to assess schizotypal traits. While Raine's three-factorial model is most commonly supported model explaining factor structure of schizotypal traits, there is also evidence supporting alternative models. The aim of this study is compare the goodness-of-fitness of various models about factor structure of the SPQ in a substantial number of university students.

METHOD

1059 university students were participated in the study. Alternative models regarding factor structure of the SPQ were compared with confirmatory factor analysis (CFA). The effect of gender on the factor structure of schizotypal traits is also studied.

RESULTS

The 4 factorial model that included cognitive-perceptual, paranoid, interpersonal and disorganized dimensions fit the data the best. Raine's three factorial model did not fit the data adequately. However, after minor modifications, Raine's model also had a satisfactory goodness-of-fit. Gender had no effect on the factor structure of the SPQ.

CONCLUSION

Results of these study supported 4-factorial model of Stefanis and modified version of Raine's model to explain factor structure of schizotypal traits. The structure of schizotypal traits is in parallel with structure of symptom dimensions in schizophrenia. This outcome is compatible with the views seeing schizotypal traits in general population in continuum with schizophrenia spectrum disorders.

Prospective memory deficits in subjects with schizophrenia spectrum disorders: a comparison study with schizophrenic subjects, psychometrically defined schizotypal subjects, and healthy controls

Memory impairment is one of the core deficits in schizophrenia. This study explored the memory profiles of schizophrenic and psychometrically defined schizotypal subjects. The study participants included 15 patients with schizophrenia, 41 schizotypal subjects, and 20 healthy controls. All of the participants completed verbal and visual memory, working memory, and prospective memory tasks. The results showed that patients with schizophrenia were impaired in all aspects of memory function, whereas the schizotypal subjects tended to show moderate to large impairment effect sizes in prospective memory. It is suggested that prospective memory be considered a potential endophenotype of schizophrenia.

Handedness and schizotypal features in healthy subjects

BACKGROUND

An excess of mixed-handedness has been repeatedly reported in schizophrenia and schizotypy. Handedness is a measure of atypical cerebral lateralization, which is considered as a risk factor for schizophrenia. Several studies have attempted to identify correlations between handedness and dimensions of psychosis but the results obtained so far remain inconclusive.

OBJECTIVE

To explore a possible link between mixed-handedness and the three classical dimensions of psychosis. As speech and language disorders may be associated with cerebral lateralization, we predicted a correlation between mixed-handedness and disorganized dimension.

METHODS

We used the Schizotypal Personality Questionnaire (SPQ) and the Edinburgh Handedness Inventory (EHI) to study the correlation between mixed-handedness scores and positive, negative or disorganized dimensions in a sample of 62 healthy subjects.

RESULTS

We found a negative correlation between mixed-handedness and the disorganized dimension of schizotypy, as individuals with prominent mixed-handedness showed more severe disorganization.

CONCLUSION

We have identified a link between mixed-handedness and the disorganized dimension that may help to identify genetic vulnerability factors involved in psychosis.

Childhood and current autistic features in adolescents with schizotypal personality disorder

The diagnostic boundaries between autistic- and schizophrenia-spectrum disorders have varied over the years, and some overlap in diagnostic criteria persists. The present study examined childhood and current signs of autistic disorder (AD) in adolescents with schizotypal personality disorder (SPD) or other personality disorders, as well as healthy controls. A structured interview was administered to rate participants' current symptoms. Participants' guardians were interviewed with the Autism Diagnostic Inventory-Revised (ADI-R), a clinical assessment of childhood and current autistic signs. Compared to both the other personality-disordered and healthy groups, adolescents with SPD were rated as having significantly more impairment on childhood and current social functioning, and having more unusual interests and behaviors. For the entire sample, impaired childhood social functioning and unusual interests and behaviors were associated with higher negative symptom scores. Current impairments in social functioning, unusual interests and behaviors, and communication were also linked with greater negative symptoms. However, neither childhood nor current autistic features significantly predicted later conversion to an Axis I psychotic disorder over the course of three years of follow-up. The findings indicate that past and current autistic signs are more common in adolescents with SPD, but neither current nor childhood autistic features are linked with conversion to psychosis.

Temperament and character as schizophrenia-related endophenotypes in non-psychotic siblings

BACKGROUND

Quantitative endophenotypes are needed to better understand the pathogenesis of schizophrenia. The psychobiological model of temperament and character suggests that personality traits are heritable and regulated by brain systems influencing schizophrenia susceptibility. Thus, measures of temperament and character may serve as schizophrenia-related endophenotypes in individuals with schizophrenia and their non-psychotic siblings.

METHODS

Individuals with schizophrenia (n=35), their non-psychotic siblings (n=34), controls (n=63), and their siblings (n=56) participated in a study of the clinical, neurocognitive and neuromorphological characteristics of schizophrenia. A mixed-model approach assessed group differences on the Temperament and Character Inventory (TCI). Neurocognitive deficits and psychopathology were correlated with the TCI. Configurations of TCI domains were examined using a generalized linear model.

RESULTS

Individuals with schizophrenia and their non-psychotic siblings had higher harm avoidance than controls and their siblings. Individuals with schizophrenia had lower self-directedness and cooperativeness, and higher self-transcendence than their non-psychotic siblings, controls, and the siblings of controls. Neurocognition was not related to temperament and character in individuals with schizophrenia or either control group. In non-psychotic siblings, self-directedness and cooperativeness were correlated with working memory and crystallized IQ.

CONCLUSION

Evidence supports harm avoidance as a schizophrenia-related endophenotype. An increased risk of schizophrenia may be associated with asociality (configured as high harm avoidance and low reward dependence), schizotypy (configured as low self-directedness, low cooperativeness, and high self-transcendence), and neurocognitive deficits (poor executive functioning, working/episodic memory, attention, and low IQ). The non-psychotic siblings demonstrated features of a mature character profile including strong crystallized IQ, which may confer protection against psychopathology.

Affect processing and positive syndrome schizotypy in cannabis users

While cannabis is associated with positive syndrome schizophrenia (SZ), it is unclear whether cannabinoids are also related to negative symptoms such as affective blunting. We examined whether cannabis use is associated with schizotypy and utilized event-related potentials (ERPs) to assess affect processing. Cannabis users demonstrated increased P300 amplitudes for unpleasant trait words, and demonstrated higher positive syndrome schizotypy which correlated with levels of cannabis use. The cannabis group also exhibited lower negative syndrome schizotypy. The lack of blunted responses during the affect ERP and decreased negative subscale schizotypy scores provide evidence that the endocannabinoid theory of schizophrenia may be primarily relevant in relation to positive syndrome SZ.

Schizotypal personality traits in Gilles de la Tourette syndrome

OBJECTIVES

Gilles de la Tourette syndrome (GTS) is a chronic tic disorder associated with comorbid psychopathology, including obsessionality, affective instability and attention-deficit hyperactivity disorder. Evidence linking GTS with schizophrenia-like symptoms is limited and equivocal, despite a common putative substrate involving dopaminergic dysfunction within frontostriatal circuits. The aim of this study was to quantify the prevalence of schizotypal traits in GTS and to detail the relationship between schizotypy and comorbid psychopathology.

MATERIALS AND METHODS

A total of 102 subjects with GTS were evaluated using the Schizotypal Personality Questionnaire and standardized neurological and psychiatric rating scales. The predictive interrelation between schizotypy, tic-related symptoms and psychiatric comorbidities was investigated using correlation and multiple regression analyses.

RESULTS

In our clinical population, 15% of the subjects were diagnosed with the schizotypal personality disorder according to the DSM-IV criteria. The strongest predictors of schizotypy were obsessionality and anxiety ratings. The presence of multiple psychiatric comorbidities correlated positively with schizotypy scores.

CONCLUSIONS

Schizotypal traits are relatively common in patients with GTS, and reflect the presence of comorbid psychopathology, related to the anxiety spectrum. In particular, our preliminary results are consistent with a shared neurochemical substrate for the mechanisms underpinning tic expression, obsessionality and specific schizotypal traits.

Nicotine consumption and schizotypy in first-degree relatives of individuals with schizophrenia and non-psychiatric controls

Individuals with schizophrenia have very high rates of cigarette smoking, and much has been discovered about the influence of nicotine on brain functioning in schizophrenia. However, less is understood about the relationship between nicotine consumption and milder phenotypes related to schizophrenia, specifically schizotypy. This study examined the relationship between nicotine consumption and schizotypy in two unmedicated samples that included first-degree relatives and non-psychiatric controls. Forty-two first-degree relatives and 50 control participants were administered a self-report questionnaire on schizotypal features as well as a self-report questionnaire on smoking behavior. A positive relationship was found between smoking status and level of schizotypy, and higher levels of schizotypy significantly predicted the odds of being a smoker after controlling for gender and group status. Interestingly, group status was a significant moderator in the relationship between level of schizotypy and smoking status, such that the relationship between these two variables was only significant in the first-degree relatives. This is the first study to investigate the relationship between these variables in a sample of first-degree relatives of individuals with schizophrenia. Those individuals with more schizotypal features are presumably at greater risk for schizophrenia-spectrum disorders and thus may be more likely to smoke cigarettes given the known biochemical effects of nicotine on overt positive and negative symptoms of schizophrenia. Although relatives did not differ from controls in their level of self-reported schizotypy, the significant relationship between smoking status and schizotypy in the former group is likely explained by their genetic vulnerability to schizophrenia-spectrum disorders.

Cognitive dimensions in first-episode schizophrenia spectrum disorders

BACKGROUND

The severity and pattern of cognitive deficits in epidemiological cohorts of patients with first-episode schizophrenia spectrum disorders still remains unclear. We aimed to characterize the basic cognitive functioning of a representative sample of patients with a first-episode schizophrenia spectrum disorders.

METHOD

One hundred thirty-one patients experiencing first-episode psychosis and 28 healthy volunteers were administered a comprehensive neuropsychological evaluation. To reduce the number of cognitive test measures into meaningful cognitive dimensions, before analyzing differences between patient and healthy volunteer samples, exploratory factor analysis was carried out on data collected in patients group. The method of extraction was Principal Components Analysis with oblique rotation.

RESULTS

An eight-factor model including verbal learning/memory, verbal comprehensive abilities, speed of processing/executive functioning, motor dexterity, motor speed, sustained attention, and impulsivity emerged. A significant below average performance in all cognitive dimensions, except impulsivity, was found. Patient's performance in speed of processing/executive functioning, motor dexterity and sustained attention dimensions exceeded one standard deviation below healthy comparison subjects.

CONCLUSIONS

At early stages of the illness, patients display a marked impairment in several functionally relevant cognitive domains.

Exophenotypical profile of adolescents with sustained attention deficit: A 10-year follow-up study

We aimed to explore prospectively the relationship between the presence of sustained attention deficit (SAD) in early adolescence and exophenotypical measures of vulnerability to schizophrenia spectrum disorders (personality and psychosocial measures) in early adulthood. Two cohorts of community adolescents were selected in 1993 according to the presence or absence of a CPT-linked SAD. In 2003, both cohorts (Index: n=42, and

CONTROL

n=38) were administered the O-LIFE, the SCID-II, the DOI battery and the COPE scale, among other tests. T-tests were used to compare both cohorts. Index subjects showed a higher level of negative schizotypy, avoidant, depressive and narcissistic personality traits, as well as more asocial behavior and poorer use of coping resources than CONTROL subjects did. A SAD in early adolescence may be associated with coping and social deficits, negative schizotypy, and personality traits indicative of emotional disturbance in adulthood. Our results suggest that SAD in early adolescence might be an indicator of psychopathology in adulthood and give support to dimensional models of psychopathology.

Schizotypal personality: neurodevelopmental and psychosocial trajectories

Schizotypal personality research holds the promise of critically important insights into the etiology and ultimate prevention of schizophrenia. This article provides a critical overview of diagnostic, developmental, demographic, psychosocial, genetic, neurodevelopmental, psychophysiological, neurochemical, neurocognitive, brain imaging, and prevention-treatment issues pertaining to this personality disorder. It is argued that genetic and early environmental influences act in concert to alter brain structure/function throughout development, resulting in disturbances to basic cognitive and affective processes that give rise to three building blocks of schizotypy-cognitive-perceptual, interpersonal, and disorganized features. Two clinical subtypes are hypothesized: (a) neurodevelopmental schizotypy, which has its roots in genetic, prenatal, and early postnatal factors, is relatively stable, has genetic affinity to schizophrenia, and may benefit preferentially from pharmacological intervention, and (b) pseudoschizotypy, which is unrelated to schizophrenia, has its roots in psychosocial adversity, shows greater symptom fluctuations, and may be more responsive to psychosocial intervention.

The initial prodrome of schizophrenia: different duration, different underlying deficits?

In light of various suggestions concerning underlying deficits and transition patterns, approaching the initial schizophrenic prodrome is a multifaceted enterprise. Recently, the prodromal phase has largely been viewed as a singular concept. However, observations of greatly varying prodromal time courses prompted us to investigate whether these differences suggest the existence of diverse prodrome subtypes. Our sample consisted of 160 patients from the Cologne Early Recognition study. The 79 patients transiting from prodrome to the Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition schizophrenia were divided into 3 time groups according to the length of the prodromal state and compared for their initial symptomatology. We found differences in the prominent clinical picture not only regarding single symptoms but also in logistic equations calculated for each group including cognitive deficits only. Our results indicate different underlying deficits: disturbances in bottom-up and top-down loop processes associated with a long prodrome and in top-down processes with medium prodrome, and a deficient central integrating system with short prodrome.

Taxonic structure of schizotypal personality in nonclinical subjects: Issues of replicability and age consistency

To assess the replicability and age consistency of the taxonic structure and base-rate of schizotypy, 803 university students (21.9 years) and 929 high school students (16.4 years) were administered three self-report measures of schizotypal personality. The two groups came from the same town and were matched on gender. MAXCOV analyses were consistent with a low base-rate taxon of approximately 10% only in the university student group; in the younger group, the three schizotypal personality measures did not show clear evidence of taxonicity. These findings support the hypothesis of the taxonic structure of schizotypal personality in adult subjects, but they raise questions concerning the identification of schizotypy in younger samples.

Prevalence of large cavum septi pellucidi and its relation to the medial temporal lobe structures in schizophrenia spectrum

Magnetic resonance imaging was used to evaluate the prevalence of the cavum septi pellucidi (CSP) in 154 schizophrenia patients, 47 schizotypal disorder patients, and 163 healthy controls. We also explored the relation of a large CSP (> or =6 mm) with medial temporal lobe structures. No significant difference was found in the prevalence of the CSP (76.0% of the schizophrenia patients, 81.6% of the controls, and 85.1% of the schizotypal patients) or the large CSP (6.5% of the schizophrenia patients, 7.4% of the controls, and 10.6% of the schizotypal patients) among the groups, but patients with a large CSP (10 schizophrenia and 5 schizotypal patients) had smaller volumes of bilateral amygdala and left posterior parahippocampal gyrus than patients without it. In the control subjects, the large CSP did not affect the volumes of the medial temporal lobe structures. These findings might reflect neurodevelopmental abnormalities in midline and associated limbic structures of the brain in schizophrenia spectrum.

Elevated social Internet use and schizotypal personality disorder in adolescents

INTRODUCTION

In the past decade, the use of the Internet as a forum for communication has exponentially increased, and research indicates that excessive use is associated with psychiatric symptoms. The present study examined the rate of Internet use in adolescents with personality disorders, with a focus on schizotypal personality disorder (SPD), which is characterized by marked interpersonal deficits. Because the Internet provides an easily accessible forum for anonymous social interaction and constitutes an environment where communication is less likely to be hampered by interpersonal deficits, it was hypothesized that SPD youth will spend significantly more time engaging in social activities on the Internet than controls.

METHODS

Self-reports of daily Internet use in adolescents with SPD (n=19), a control group with other personality disorders (n=22) and a non-psychiatric control group (n=28) were collected.

RESULTS

Analyses revealed that the SPD participants reported significantly less social interaction with 'real-life' friends, but used the Internet for social interaction significantly more frequently than controls. Chat room participation, cooperative Internet gaming, and to a lesser degree, e-mail use, were positively correlated with ratings of SPD symptom severity and Beck Depression Inventory scores.

DISCUSSION

Findings are discussed in light of the potential benefits and risks associated with Internet use by socially isolated SPD youth.

[Handedness, emotional problems, and schizotypy]

The purpose of this study was to analyse the relationship between emotional or behavioural problems and schizotypy. An assessment of handedness and schizotypal personality traits were also performed by means of the Thinking and Perceptual Style Questionnaire, the Multidimensional Schizotypal Traits Questionnaire, the Edinburgh Handedness Inventory, and the Youth Self-Report. The sample comprised 296 participants with a mean age of 13.8 and a standard deviation of 1.34. Data indicate that adolescents with high scores on psychometric factors of schizotypy displayed higher patterns of problem behaviours as well as a significant difference in all the core factors of the Youth Self-Report, compared to those who scored low on these measures. Discriminant analysis showed that the core factors of the Youth Self-Report correctly classified 84% of the adolescents with high or low scores on psychometric schizotypy. Lastly, no significant association between the factors of schizotypy and left-handedness, right-handedness, or mixed-handedness was found.

Self-report of attenuated psychotic experiences in a college population

This study assessed the rates of self-reported "prodromal" psychotic symptoms and related distress in a college population. 1020 students completed the Prodromal Questionnaire (PQ), a self-report screening measure for psychosis risk. Participants' responses were highly similar to the responses of non-psychotic-spectrum patients in the original PQ validation sample [Loewy, R.L., Bearden, C.E., Johnson, J.K., Raine, A., Cannon, T.D., 2005. The Prodromal Questionnaire (PQ): preliminary validation of a self-report screening measure for prodromal and psychotic syndromes. Schizophr. Res. 79 (1) 117-125], suggesting that the PQ may perform similarly with a variety of populations. Applying the cutoff proposed for screening treatment-seeking patients (8 or more positive symptoms) identified 43% of students, while comparatively fewer participants (25%) endorsed eight or more items at the frequency required for prodromal syndrome diagnosis by interview (i.e., weekly), and only 2% endorsed eight or more items as distressing. Although attenuated psychotic experiences are commonly reported by "normal" young adults, frequent and distressing items identify a proportion of students more consistent with the prevalence of psychotic-spectrum disorders in the general population, which suggests a potential for future screening of unselected samples.

A bias against disconfirmatory evidence is associated with delusion proneness in a nonclinical sample

Previous work has suggested that a bias against disconfirmatory evidence (BADE) may be associated with the schizophrenia spectrum. The current investigation focused on whether a BADE (1) overlaps with traditional measures of memory and executive functions or selectively taps into a unique aspect of cognition and (2) is correlated with delusional ideation but not with other aspects of schizotypy. Sixty-eight undergraduate students were administered the Schizotypal Personality Questionnaire (SPQ), the BADE test, the Rey Auditory Verbal Learning Test (RAVLT), the Wisconsin Card Sorting Test (WCST), the Trail Making Tests A and B (TMT), and tests used to estimate IQ. Factor analysis of all cognition measures resulted in a 6-factor solution, 4 of which reflected the 4 domains of neuropsychological tests (WCST, RAVLT, TMT, and IQ), and 2 of which reflected different aspects of the BADE test: Initial Belief and Integration of Disconfirmatory Evidence. This solution suggests that BADE measures were independent from the other cognitive domains measured. Integration of Disconfirmatory Evidence was the only factor that correlated with delusion-content subscales of the SPQ, providing support for the contribution of a BADE to delusional ideation.