Schizotypal Personality Scale Research Articles

Attenuated psychotic symptoms, substance use and self-reported PTSD in adolescence

ABSTRACT Background: The occurrence of attenuated psychotic symptoms (APS) is a major concern in populations with substance use disorders (SUDs). However, APS also frequently develop in the course of Post-Traumatic Stress Disorder (PTSD). This study explores how the prevalence of APS differs between adolescent patients with only SUD, SUD with a history of traumatic experiences (TEs), and with SUD and self-reported PTSD. Methods: We recruited n = 120 treatment-seeking adolescents at a German outpatient clinic for adolescents with SUD. All participants filled out questionnaires assessing APS (PQ-16, YSR schizoid scale), trauma history, PTSD symptoms (both UCLA PTSD Index), and SUD severity (DUDIT) next to an extensive substance use interview. We performed a multivariate analysis of co-variance with the four PQ-16 scales and the YSR scale as outcomes and PTSD status as predictor. Additionally, we performed five linear regressions predicting each PQ-16 score and YSR score based on tobacco, alcohol, cannabis, ecstasy, amphetamine, and methamphetamine use. Results: Participants with co-occurring SUD and self-reported PTSD showed significantly higher APS prevalence rates (PQ-16 score, p = .00002), more disturbed thought content (p = .000004), more perceptual disturbances (p = .002), more negative symptoms (p = .004) and more thought problems (p = .001) compared to adolescents with SUD and a history of trauma and adolescents with only SUD. Past-year substance use was not predictive for APS prevalence (F(75) = 0.42; p = .86; R 2 = .04). Conclusion: Our data suggests that the occurrence of APS in adolescents with SUD is better explained by co-occurring self-reported PTSD than by substance use frequency or substance class. This finding might indicate that APS might be reduced through treating PTSD or focusing on TEs in SUD therapy.

Examination of the Prefrontal Cortex Hemodynamic Responses to the Fist-Edge-Palm Task in Naïve Subjects Using Functional Near-Infrared Spectroscopy.

The Fist-Edge-Palm (FEP) task, a manual hand task, has been used to detect frontal dysfunctions in clinical situations: its performance failures are observed in various prefrontal cortex (PFC)-related disorders, including schizophrenia. However, previous imaging studies reported that the performance of the FEP task activated motor-related areas, but not the PFC. Here, we aimed to investigate the relationships between the performance of the FEP task and PFC functions. Hemodynamic activity in the PFC, including the dorsolateral PFC (area 46) and frontal pole (area 10), was recorded. Healthy young subjects performed the FEP task as well as a palm tapping (PT) task (control task) three times. The subjects also completed a Wisconsin Card Sorting Test (WCST) and Schizotypal Personality Scale (STA) questionnaire. We found that hemodynamic activity (Oxy-Hb) in the PFC increased in the first trial of the FEP task but decreased considerably in the second and third trials compared to the PT task. The number of performance errors in the FEP task also decreased in the second and third trials. Error reduction (i.e., learning) in the FEP task between the first and second trials was negatively correlated with schizotypal trait and the number of perseveration errors in the WCST. Furthermore, changes in the PFC hemodynamic activity between the first and second trials were positively correlated with error reduction in the FEP task between the first and second trials, and negatively correlated with the number of perseveration errors in the WCST. These results suggest that learning in the FEP task requires PFC activation, which is negatively associated with perseveration errors in the WCST. The results further suggest that the FEP task, in conjunction with near-infrared spectroscopy, may be useful as a diagnostic method for various disorders with PFC dysfunction.

Personality traits in adults with hoarding disorder

Background: Prior research has demonstrated a link between compulsive hoarding symptoms and personality traits; however, no studies have investigated the link between hoarding and personality traits utilizing a sample of individuals diagnosed with hoarding disorder (HD) using formal diagnostic criteria. The aim of the current study was to evaluate the frequency and type of personality traits in adults diagnosed with HD and to explore the associations among hoarding severity and personality disorder traits within this sample.Methods: Seventy-two veterans enrolled in an ongoing treatment trial for HD completed a battery of self-report measures during their initial assessment. Linear regression analyses were used to determine the unique variance accounted for by hoarding severity in predicting scores on the personality disorder scales from the Millon Clinical Multiaxial Inventory-III (MCMI-III).Results: The majority of participants had an elevated score on at least one of the MCMI-III Personality scales. The most frequently elevated scores were for the Avoidant, Dependent, Depressive, and Schizoid scales. Hoarding severity was a significant predictor of personality traits in 10 out of 14 MCMI-III scales.Limitations: Given the exploratory nature of the investigation, we did not control for multiple comparisons or the presence of mood or anxiety disorders.Conclusions: The elevated prevalence of co-occurring personality pathology in adults with HD indicates the importance of considering underlying personality structure when developing individualized treatment plans.

Personality characteristics of victims of intimate partner violence: A systematic review

Abstract Intimate partner violence (IPV) is global public health issue and refers to the violence committed by a partner in the context of an intimate relationship, regardless of whether or not it is legally recognized. This review aims to analyze the personality characteristics present in victims of IPV, addressing the causes and consequences of the abusive relationship. Studies focusing on female victims were obtained through multiple databases, following the Cochrane Collaboration procedures. Of the 87 documents collected, 31 were retained for further analysis and considered eligible for inclusion, with ten studies from manual search being included. The objectives, methodological aspects (sample/instruments), and main conclusions were extracted from each study. The results suggest that women tend to become victims when they experience violence during childhood, when they are economically dependent, lack social support, and fear for their lives. The consequences consist of physical and psychological sequelae that remain throughout life. There are personality traits that make the victim susceptible to remaining in an abusive relationship. Women who have experienced IPV obtained higher scores in schizoid, avoidant, self-destructive, schizotypal, borderline, and paranoid personality scales. Therefore, female victims exhibit characteristics such as low personal self-esteem, family and social isolation, dependency (economic and emotional), insecurity, inferiority, submissiveness, and pacification. This review is particularly useful for clinical practice and intervention with victims of IPV, by bringing to light specific personality traits, cognitive schemas and/or possible diagnoses that are most common among these victims and make them more vulnerable to remaining in abusive relationships.

Schizotypy from the Perspective of the DSM-5 Alternative Model of Personality Traits: a Study on a Sample of 1056 Italian Adult University Students

To assess the relationships between schizotypy measures and DSM-5 Alternative Model of Personality Disorders (AMPD) traits, 1056 (69.4% female; mean age = 23.30 years) University students, were administered the Italian translation of the Schizotypal Personality Questionnaire (SPQ), Schizotypal Personality Scale (STA), Schizotypy Scale (SS), and Personality Inventory for DSM-5 (PID-5). Exploratory structural equation modeling (ESEM) suggested that the SPQ, STA, and SS Schizofrenism scale total scores may represent primary measures of schizotypy/Schizotypal personality disorder (PD), whereas the SS anhedonia (AH) total score represent an index of the general anhedonia level. MAMBAC, MAXCOV, and LMode taxometric analyses showed that both schizotypy and anhedonia constructs had a dimensional distribution (all comparison curve fit index values<.40). Bayesian confirmatory factor analysis (CFA) supported a two-factor model of SPQ, STA, SS SZ and SS AH scale total scores. Hierarchical regression analyses showed that DSM-5 AMPD traits that were hypothesized to define the Schizotypal PD profile (i.e., Cognitive and Perceptual Dysregulation, Unusual Beliefs and Experiences, Eccentricity, Restricted Affectivity, Withdrawal, and Suspiciousness), as well as the additional specifiers (i.e., Anxiousness, and Depressivity) explained 66.0% of the systematic variance in the schizotypy factor scale scores. Our findings suggested that schizotypy could be represented as a continuously-distributed latent variable which may be effectively described in terms of a coherent system of dysfunctional personality traits.

Early maladaptive schemas in patients with schizophrenia and non-patients with high and low schizotypal traits and their differences based on depression severity

BackgroundThe aims of this study were to predict positive and negative symptoms of psychosis via early maladaptive schemas (EMSs) in patients with schizophrenia (SZ); to compare EMSs among SZ patients, non-patients with high schizotypal traits, and non-patients with low schizotypal traits; and to compare EMSs among subgroups concerning depression severity. MethodsWe applied three groups of participants including SZ patients (n = 105), non-patients with low schizotypal traits (n = 90), and non-patients with high schizotypal traits (n = 90). Participants completed the Young Schema Questionnaire-Short Form (YSQ-SF), the Positive and Negative Syndrome Scale (PANSS), the Schizotypal Personality Scale (STA), and the Beck Depression Inventory-II (BDI-II). ResultsThe results indicated that the mistrust/abuse and social isolation schemas were significant predictors of positive and negative symptoms in SZ patients respectively. SZ patients and non-patients with high schizotypal traits exceeded non-patients with low schizotypal traits on all EMSs. There were no differences between SZ patients and non-patients with high schizotypal traits regarding EMSs. In the subgroups with high depression, SZ patients showed higher levels of EMSs than non-patients with low and high schizotypal traits. In the subgroups with low depression, both SZ patients and non-patients with high schizotypal traits had higher scores on EMSs than non-patients with low schizotypal traits. ConclusionThe findings suggest that mistrust/abuse and social isolation may be specific to psychosis symptoms. Also, SZ and schizotypal traits may overlap in relation to EMSs. In addition, the activated EMSs may contribute to high depression in SZ.

Schizotypal traits are associated with sleep spindles and rapid eye movement in adolescence.

Research suggests an association between schizophrenia and a decrease in sleep spindle activity, as well as a change in sleep architecture. It is unknown how the continuum of psychotic symptoms relates to different features in the sleep electroencephalogram. We set out to examine how sleep architecture and stage 2 spindle activity are associated with schizotypy in a healthy adolescent population. The participants in our study (n=176, 61% girls) came from a community-based cohort. Schizotypal traits were evaluated using the Schizotypal Personality Scale (STA) in early adolescence (mean age 12.3years, SD=0.5) and the participants underwent ambulatory overnight polysomnography at mean age 16.9years (SD=0.1). Sleep was scored in 30-s epochs into stages 1, 2, 3 and rapid eye movement (REM) sleep. Stage 2 spindles were detected using an automated algorithm. Spindle analyses from central and frontal derivations included spindle duration and density for slow (10-13Hz) and fast (13-16Hz) ranges. Covariates included sex and age. Those with the highest STA scores had a higher percentage of REM (B=2.07 [95% CI, 0.17, 4.0]; p=.03) than those with the lowest scores. Those with the highest scores had shorter spindle duration, as derived from the frontal regions, and a slower oscillation range (B=-0.04 [95% CI, -0.07, -0.01]; p=.023) than those with the lowest scores. We conclude that high levels of schizotypy characteristics measured in early adolescence may be associated with distinguished features of sleep architecture, namely with spindle morphology and a higher proportion of REM sleep.

Associations of Schizotypal Personality and Paranoid Ideation With the Degree of Flow Experience in Daily Life

Background: Flow experience is thought to enhance health-related quality of life by mitigating stress and providing a sense of achievement. The associations between flow experience and subclinical psychiatric anomalies, such as schizotypal personality traits and paranoid ideation, have not been examined. Objectives: This study aimed to evaluate the associations between flow experience and subclinical psychiatric anomalies in a healthy population. Materials and Methods: This cross-sectional study included 64 undergraduates from Kibi international university, Japan (42 males, 22 females; mean age 20.1 ± 1.13 years). Schizotypal personality was measured using the Japanese version of the Oxford Schizotypal Personality Scale (STA). Paranoia was measured using the Japanese-version Paranoia Checklist (JPC). Flow experience was measured using the Flow Experience Checklist (FEC). Results: Both the STA score and the JPC distress subscore were positively correlated with the FEC score. However, no correlation was observed between either the JPC conviction or the frequency subscore and the FEC score. Stepwise multiple regression analysis revealed that the FEC score was influenced only by the STA score. Conclusions: Schizotypal personality traits appear to enhance the quality of flow experiences, but not their frequency or duration. We suggest that these intense flow experiences serve as a distraction from psychological abnormalities, such as paranoid ideation.

Schizotypy and Religiosity: The Magic of Prayer

The term schizotypy is used to describe a diverse range of characteristics symptomatic of schizotypal personality disorder and borderline personality disorder. An emerging body of research is concerned with the relationship between schizotypy and religiosity. Mixed findings suggest a gender-specific, weak positive association between schizotypy and religiosity. The present aim was to clarify the relationship between schizotypy and religiosity by employing a multidimensional measure of prayer as a measure of religiosity. A sample of 371 Irish respondents completed the Measure of Prayer Type and the Schizotypal Personality (STA) and Borderline Personality (STB) Scales. Multiple regression showed that Magical Thinking uniquely predicted all prayer types, controlling for age and gender.

Schizotypy and personality profiles of Cluster A in a group of schizophrenic patients and their siblings

BackgroundSchizotypy, or the set of personality traits related to schizophrenia, is considered an endophenotypic manifestation that is more represented in first-degree relatives of patients with schizophrenia than in the general population. The assessment of schizotypy is primarily based on self-reports, and for this reason it presents several limitations. In order to assess schizotypy, this study proposes a diagnostic instrument based on clinical reports.MethodsA sample of 66 subjects, composed of 25 outpatients with schizophrenia, 18 siblings of these patients and 23 healthy controls, was subjected to the personality assessment test SWAP-200 by trained clinical interviewers. To test the hypothesis of the difference between the profiles of the Personality Disorders within the schizophrenia spectrum, a Multivariate Analysis of Variance and subsequent planned comparisons were conducted.ResultsPatients with schizophrenia scored higher than both their siblings and the controls on all SWAP-200 scales; their siblings, compared to the healthy controls, showed significant statistical differences, with higher mean scores for paranoid (F(1,63) = 7.02; p = 0.01), schizoid (F(1,63) = 6.56; p = 0.013) and schizotypal (F(1,63) = 6.47; p = 0.013) traits (PD T scores of Cluster A and Q-factor scores for the schizoid scale [F(1,63) = 6.47; p = 0.013]).ConclusionsConsistent with previous data, first-degree relatives of patients with schizophrenia scored higher on schizophrenia-related personality traits than a general population comparison sample. SWAP-200, as an alternative diagnostic instrument to self-report measures, is able to reveal the higher prevalence of schizotypal traits in siblings of patients with schizophrenia, suggesting its possible use as a complementary instrument for the assessment of schizophrenia.

Psychohygienic estimation of features of the formation of properties of character of pupils aged 14-17 years in the dynamics of learning at modern schools.

The aim of scientific work was psychohygienic estimation of features of the formation of properties of character of pupils aged 14-17 years old in the dynamics of learning at modern schools. The studies were conducted on the basis of secondary schools in the city of Vinnitsya. Evaluation of the formation of properties of character was carried out using a personality questionnaire Mini-mult. It was determined that in the structure of personal profile of properties of character in girls aged 14-17 years during the period of study at school predominance of characterologic features according to schizoid scales (Se) and pscychasthenia (Pt) (block 1 of characterologic features), hypochondria (Hs) and depression (D) (block 2 of characterologic features), hypomania (Ma) and hysteria (Hy) (block 3 of characterologic features is registered). In the structure of personal profile of properties of character of boys of 14-17 years during the period of study at school predominance of characterologic properties according to psychasthenia (Pt) and schizoid (Se) (block 1 of characterologic features), hypochondria (Hs) and depression (D) (block 2), paranoid (Pa) and hypomania (Ma) (block 3) is registered. The results suggest the need to consider the properties of character of schoolchildren in development of health-saving technologies, sanitation measures and psychohygienic effect on the pupils’ organism.

Dopaminergic basis of the psychosis-prone personality investigated with functional magnetic resonance imaging of procedural learning.

Previous evidence shows a reliable association between psychosis-prone (especially schizotypal) personality traits and performance on dopamine (DA)-sensitive tasks (e.g., prepulse inhibition and antisaccade). Here, we used blood oxygen level-dependent (BOLD) fMRI and an established procedural learning (PL) task to examine the dopaminergic basis of two aspects of psychosis-proneness (specific schizotypy and general psychoticism). Thirty healthy participants (final N = 26) underwent fMRI during a blocked, periodic sequence-learning task which, in previous studies, has been shown to reveal impaired performance in schizophrenia patients given drugs blocking the DA D2 receptor subtype (DRD2), and to correspond with manipulation of DA activity and elicit fronto-striatal-cerebellar activity in healthy people. Psychosis-proneness was indexed by the Psychoticism (P) scale of the Eysenck Personality Questionnaire-Revised (EPQ-R; 1991) and the Schizotypal Personality Scale (STA; 1984). EPQ-R Extraversion and Neuroticism scores were also examined to establish discriminant validity. We found a positive correlation between the two psychosis-proneness measures (r = 0.43), and a robust and unique positive association between EPQ-R P and BOLD signal in the putamen, caudate, thalamus, insula, and frontal regions. STA schizotypy score correlated positively with activity in the right middle temporal gyrus. As DA is a key transmitter in the basal ganglia, and the thalamus contains the highest levels of DRD2 receptors of all extrastriatal regions, our results support a dopaminergic basis of psychosis-proneness as measured by the EPQ-R Psychoticism.

Psychometric properties of Peters et al. Delusions Inventory-21 in adolescence

We explored the psychometric properties of the Korean version of the Peters et al. Delusions Inventory-21 (PDI-21) and evaluated the item characteristics of the PDI-21 compared with the Magical Ideation Scale (MIS) in Korean community adolescents. Survey participants comprised 310 Year 10 students who were assessed with the following instruments: the PDI-21, the MIS, the Schizotypal Personality Scale (STA) and the Symptom Checklist-90-R (SCL-90-R). The item characteristics of the PDI-21 and MIS were also explored using item response theory (IRT). The PDI-21 exhibited good internal consistency and demonstrated significant correlations with the MIS, STA and all subscale scores of the SCL-90-R, indicating psychological distress in adolescents with high PDI-21 scores. We also found through IRT analysis that the PDI-21 provides more information at the lower range and the MIS at the higher range of delusion proneness. Our findings suggest that the PDI-21 is an effective and reliable self-report measure for assessment of delusion proneness and that the PDI-21 and the MIS may be used complementarily to assess a broad range of delusion proneness among community adolescents.

Neural correlates of reality monitoring during adolescence

BackgroundReality monitoring processes serve the critical function of discriminating between externally derived information and self-generated information. Several reality monitoring studies with healthy adult participants have identified the anterior prefrontal cortex (PFC) as consistently engaged during the recollection of self-generated contextual cues. Furthermore, reduced activity of medial PFC has been linked with schizotypal trait expression of delusion and hallucination-like symptoms in healthy adults undergoing fMRI reality-monitoring tasks. The present study seeks to examine the cerebral underpinnings of reality monitoring during adolescence, a developmental stage where the expression of schizotypal traits may increase risk for psychosis. MethodA group of 33 adolescents, assessed using the Schizotypal Personality Scale (SPQ), underwent fMRI while performing a reality monitoring task. After an encoding session where the subject or the experimenter read out a series of complete or incomplete word pairs, subjects were presented with the first word of studied word pairs and asked whether the corresponding word had been: (1) perceived or produced (context monitoring), or (2) read by the subject or by the experimenter (origin monitoring). ResultsAnalyses revealed a common set of activated brain areas during both context and origin monitoring conditions. When compared to context monitoring, origin monitoring was associated with greater activation in anterior PFC within Brodmann area 10 (BA 10). Correlation analyses revealed that reduced signal change in BA 10 during origin monitoring was associated with greater schizotypal trait expression. ConclusionMuch like adults performing a similar reality monitoring task, adolescents exhibit a common pattern of brain activity during origin and context monitoring, with functional specialization within the prefrontal cortex involving preferential activation of BA 10 during origin monitoring. Greater schizotypal trait expression appears to be significantly associated to reduced BA 10 activity during origin monitoring trials. Results are discussed in relation to cortical specialization within the PFC and trait expression during adolescence.

Reliability and Validity of the Japanese Version of the Oxford Schizotypal Personality Scale

Reliability and Validity of the Japanese Version of the Oxford Schizotypal Personality Scale

Catechol-o-Methyltransferase Genotype and Childhood Trauma May Interact to Impact Schizotypal Personality Traits

We attempt to identify gene by childhood abuse interactions which predispose to the development of schizotypal traits in a familial bipolar disorder (BD) sample. Self-report measures of schizotypal personality traits (Schizotypal Personality Scale) and childhood maltreatment (Childhood Trauma Questionnaire) were administered to 222 participants from 44 families with BD. Variants of catechol-o-methyltransferase (COMT) and four other dopamine pathway-related genes: DRD4, DRD2,MAOA, and SLC6A3, were typed. BD type I (BD I) subjects scored significantly higher than their unaffected relatives on the Schizotypal Personality Scale. The val allele of the Val158 Met polymorphism of the COMT gene was associated with increased schizotypal personality trait scores in individuals exposed to higher levels of self-reported childhood trauma (p < 0.05). There was no direct effect of the val158met polymorphism on schizotypal personality traits. Further, no passive correlation between COMT genotype and childhood trauma was found. We raise the possibility that genetically-driven variation in COMT may interact with childhood trauma to contribute to the risk of developing schizotypal personality traits.

Neuropsychological status of bipolar I disorder: impact of psychosis

The presence of schizotypal personality traits in some people with bipolar disorder, together with reports of greater cognitive dysfunction in patients with a history of psychotic features compared with patients without such a history, raises questions about the nosological relationship between bipolar disorder with psychotic features and bipolar disorder without psychotic features. To test the impact of a history of DSM-IV-defined psychosis on the neuropsychological status of participants with bipolar disorder while statistically controlling for confounding factors such as mood, medication, alcohol misuse/dependence and childhood abuse, and to evaluate the impact of schizotypal personality traits (and thus potential vulnerability to psychotic illness) on the cognitive performance of people with bipolar disorder and their healthy relatives. Neuropsychological data were obtained for 25 participants with type I bipolar disorder and a history of psychosis, 24 with type I bipolar disorder but no history of psychosis and 61 unaffected relatives. Schizotypal traits were measured with the Schizotypal Personality Scale (STA). Childhood trauma was measured with the Childhood Trauma Questionnaire. The group with a history of psychosis performed significantly worse than the healthy relatives on measures of verbal working memory, cognitive flexibility and declarative memory. Nevertheless, the two bipolar disorder groups did not differ significantly from each other on any cognitive measure. Scores on the STA were negatively associated with verbal working and declarative memory, but positively associated with visual recall memory. 'Psychotic' and 'non-psychotic' subtypes of bipolar disorder may lie on a nosological continuum that is most clearly defined by verbal memory impairment.

Apophenia, theory of mind and schizotypy: Perceiving meaning and intentionality in randomness

Impaired ability to correctly infer others' mental states (‘Theory of Mind’ – ToM) and the tendency to perceive meaning in unrelated events (‘apophenia’) have been implicated in vulnerability to schizophrenia. Sixty-three healthy participants completed three experimental tasks that provided indices of ToM and apophenia. The first task (Contingency) required participants to rate the strength of relationship between the movements of two shapes; in some conditions the movements were unrelated, in others the movement of one shape was contingent on that of the other. In the second task (Stories), participants answered questions on short stories with ‘random’, ‘physical’ or ‘ToM’ themes. The third task (Triangles) required participants to view and then describe the movement of triangles on a computer screen in ‘random’, ‘physical’ and ‘ToM’ conditions. Participants completed questionnaire measures of psychosis-proneness (the Schizotypal Personality Scale – STA) and delusional thinking style (Peters et al. Delusions Inventory – PDI-21). Little evidence was found on any of the tasks for an association between a specific deficit in ToM accuracy and any aspect of psychosis-proneness. On the Triangles task, schizotypal and delusion-prone participants spontaneously reported perceiving a greater number of associations in the random condition (apophenia). On both the Triangles and Contingency tasks, over-mentalizing was found to be associated with delusional thinking but not with general schizotypy. We speculate that over-mentalizing may be underpinned by a hyper-associative cognitive style, linked to an exaggeration of the normal human tendency to attribute mental states, rather than to dysfunction in the assessment of causality. Perceiving meaning in randomness and, more particularly, attributing mental states where none are indicated, may be important factors in the formation of paranormal and delusional beliefs.

The Effect of Anxiety on the Cognitive Functioning in Non-clinical Schizotypal Individuals

Schizotypal personality disorder (SPD) is characterized by eccentric behavior and perceptual distortions that closely resemble the patterns observed in those with schizophrenia. Schizophrenia and related personality disorders (i.e., SPD) are associated with deficits in sustained attention, slower than normal reaction times, and manifestations of working memory deficits and erratic cognitive tasks. The present study used the schizotypal personality scale (STA) to compare cognitive abilities of self-reported low schizotypic tendency subjects with high schizotypic tendency subjects. The group scores on the STA differed significantly. Those with high STA scores also tended to have higher state and trait anxiety scores based on the State-Trait Anxiety Inventory (STAI). The groups did not significantly differ on any of the demographic variables tested, including age, education, self-rated health status, and medication. Along with an executive function test, two computerized tasks tested subjects on reaction time and memory. Even when covariates (i.e., state, trait anxiety scores) were analyzed, there were no significant differences between the groups and tasks, although the gathered data showed trends in the expected direction.

Measuring psychosis proneness in a nonclinical Korean population: is the Peters et al Delusions Inventory useful for assessing high-risk individuals?

Objectives We examined the psychometric properties of the Korean version of the Peters et al Delusions Inventory (PDI) 40 and investigated the distribution of delusional ideation in a nonclinical population. We also used the item response theory to evaluate the usefulness of the PDI in measuring the risk for psychosis. Methods A total of 310 nonclinical individuals completed the Korean PDI-40, the Magical Ideation Scale (MIS), and the Schizotypal Personality Scale (STA). In addition, 60 psychotic inpatients with delusions completed the PDI-40. Among 310 individuals, 124 participated in a follow-up study 6 months after completing their original questionnaire. Results The PDI-40 revealed a slightly skewed distribution, but the score range was similar to that of the British population. Scores were negatively correlated with age, but no sex differences were found. The Korean PDI-40 exhibited good internal consistency and test-retest reliability. The PDI was significantly correlated with the MIS and the STA. Ten components were extracted through a principal component analysis with varimax rotation. The test results using item response theory revealed 39 items as the items which individuals with very high level of psychosis proneness will answer as “yes.” Moreover, all items yielded “above moderate” discrimination in terms of psychosis proneness. Conclusions We confirmed the reliability and validity of the Korean PDI-40. The usefulness of the PDI-40 in a nonclinical population was replicated in the Korean sample. The PDI-40 can be used as an informative device when investigating “psychosis proneness” in a group at high risk for psychosis.