The measurement invariance of schizotypy in Europe

Variation of subclinical psychosis across 16 sites in Europe and Brazil: findings from the multi-national EU-GEI study

BACKGROUND

Incidence of first-episode psychosis (FEP) varies substantially across geographic regions. Phenotypes of subclinical psychosis (SP), such as psychotic-like experiences (PLEs) and schizotypy, present several similarities with psychosis. We aimed to examine whether SP measures varied across different sites and whether this variation was comparable with FEP incidence within the same areas. We further examined contribution of environmental and genetic factors to SP.

METHODS

We used data from 1497 controls recruited in 16 different sites across 6 countries. Factor scores for several psychopathological dimensions of schizotypy and PLEs were obtained using multidimensional item response theory models. Variation of these scores was assessed using multi-level regression analysis to estimate individual and between-sites variance adjusting for age, sex, education, migrant, employment and relational status, childhood adversity, and cannabis use. In the final model we added local FEP incidence as a second-level variable. Association with genetic liability was examined separately.

RESULTS

Schizotypy showed a large between-sites variation with up to 15% of variance attributable to site-level characteristics. Adding local FEP incidence to the model considerably reduced the between-sites unexplained schizotypy variance. PLEs did not show as much variation. Overall, SP was associated with younger age, migrant, unmarried, unemployed and less educated individuals, cannabis use, and childhood adversity. Both phenotypes were associated with genetic liability to schizophrenia.

CONCLUSIONS

Schizotypy showed substantial between-sites variation, being more represented in areas where FEP incidence is higher. This supports the hypothesis that shared contextual factors shape the between-sites variation of psychosis across the spectrum.

Mediating role for metacognitive processes in the relationship between schizotypy and anxiety and depression symptoms

Introduction: Depression and anxiety symptoms are highly prevalent in schizophrenia-spectrum disorders and are commonly associated with schizotypy in non-clinical samples. However, it remains unclear what factors could be contributing to the relationships between schizotypy and anxiety and depression symptoms. Using path analysis, we explored the complex interplay between schizotypy, metacognitive beliefs, cognitive insight, and symptoms of emotional distress.Methods: Self-report data of schizotypy, metacognitive beliefs, cognitive insight, depression, and anxiety symptoms were collected from 344 participants from a predominantly student sample.Results: Path analysis confirmed unique associations between schizotypy dimensions, metacognitive beliefs, and cognitive insight. Furthermore, negative beliefs about worry mediated the link between the schizotypy dimensions, unusual experiences, cognitive disorganisation, and introvertive anhedonia and both depression and anxiety symptoms. Lack of cognitive confidence also mediated the relationship between cognitive disorganisation and depression symptoms. Finally, the cognitive insight subcomponent self-reflectiveness mediated the relationship between unusual experiences and cognitive disorganisation and anxiety.Conclusions: This study significantly furthers our understanding of the complex relationship between schizotypy, metacognitive processes, and emotional distress. Our findings also provide support for interventions which modify metacognitive beliefs and self-reflectiveness, which may prove beneficial for treatment in clinical settings.

Gender Differences in the Correlations between Childhood Trauma, Schizotypy and Negative Emotions in Non-Clinical Individuals

Early life trauma has a negative impact on the developing brain, and this can lead to a wide range of mental illnesses later in life. Childhood trauma is associated with increased psychotic symptoms and negative emotions such as depressive, anxiety, and stress symptoms in adulthood. Childhood trauma has also been shown to influence sub-clinical ‘schizotypy’ characteristics of psychosis in the general population. As it has been reported that mental health outcomes after early life trauma exposure are influenced by gender, the current study aimed to investigate the gender differences in the relationship between childhood trauma, schizotypy and negative emotions. Sixty-one non-clinical participants (33 men and 28 women) aged between 18 and 45 completed self-report questionnaires to measure early life trauma, schizotypy and negative emotions. Despite similar levels of childhood trauma in men and women, early life trauma in women was associated with increased schizotypy personality characteristics (Cognitive Disorganisation) and increased depression, anxiety and stress later in life, but no correlations were observed in men. Our findings suggest that the sociocultural and biological processes affected by early life adversities may differ between the genders. Women may be more vulnerable to the influence of childhood trauma, which may be associated with increased psychopathology later in life.

Adaptive and maladaptive features of schizotypy clusters in a community sample

Schizotypal personality traits correlate with psychopathology and impaired functional outcome. Yet advantageous aspects of positive schizotypy may exist which could promote resilience and creativity, and several studies have identified a high positive but low negative schizotypy group with some signs of adaptation. The aim of our study was to clarify whether such individuals demonstrate only traits associated with well-being, or they also have traits that predict impairment. Participants (N = 643 students, 71.5% female) completed measures of schizotypy, resilience, self-esteem, self-concept clarity, and absorption. We identified four clusters: an overall low schizotypy, an overall high schizotypy, a disorganised-interpersonal schizotypy and a positive schizotypy cluster. The overall high schizotypy cluster seemed to be the most vulnerable as it was the least resilient and showed widespread maladaptation, whereas the high positive schizotypy cluster had intact self-esteem and high resilience and its elevated absorption may hold the promise for adaptive outcomes such as creativity and positive spirituality. However, the high positive schizotypy cluster lacked self-concept clarity. The results suggest that individuals showing high positive and low negative schizotypy demonstrate features promoting mental well-being to an extent that is higher than in all the other clusters, while their self-concept impairment is similar to that observed in the high and the disorganised-interpersonal schizotypy clusters. Better understanding of these factors could be informative for prevention and treatment of psychosis-spectrum disorders.

The network structure of schizotypy in the general population

Schizotypal personality traits show similarity with schizophrenia at various levels of analysis. It is generally agreed that schizotypal personality is multidimensional; however, it is still debated whether impulsive nonconformity should be incorporated into theories and measurement of schizotypy. In addition, relatively little is known about the network structure of the four-dimensional model of schizotypal personality. To estimate the network structure of schizotypy, we used data from participants recruited from the community (N = 11,807) who completed the short version of the Oxford-Liverpool Inventory of Feelings and Experiences, a widespread self-report instrument that assesses the positive, negative, disorganised and impulsive domains of schizotypy. We performed community detection, then examined differences between communities in terms of centralities and compared the strength of edges within and between communities. We found communities that almost perfectly corresponded to the a priori-defined subscales (93% overlap, normalised mutual information = 0.74). Items in the disorganisation community had higher closeness centrality relative to items in the other communities (Cliff's Δs ranged from 0.55 to 0.83) and weights of edges within the disorganisation community were stronger as compared to the negative schizotypy and impulsive nonconformity communities (Cliff's Δs = 0.33). Our findings imply that the inclusion of impulsive nonconformity items does not dilute the classical three-factor structure of positive, negative and disorganised schizotypy. The high closeness centrality of disorganisation concurs with theories positing that cognitive slippage and associative loosening are core features of the schizophrenic phenotype.

Measurement Invariance of Psychotic-Like Symptoms as Measured With the Prodromal Questionnaire, Brief Version (PQ-B) in Adolescent and Adult Population Samples

Valid measurement of group differences in self-reported psychotic-like experiences (PLEs) requires knowing any group-specific measurement properties of the instruments. We investigated the measurement invariance of the 21-item Prodromal Questionnaire-Brief (PQ-B) questionnaire across gender, ethnic minority/majority status, and presence of depressive symptoms in two different US non-clinical undergraduate samples (N = 1,099). For each item, endorsement of the experience and the associated distress were combined for analysis. A unidimensional model of the PQ-B fit the data well. Across genders, the PQ-B showed configural and metric, but not full scalar invariance; there were statistically significant differences in eight thresholds of six items, most being higher endorsement thresholds for self-identified females. Partial scalar invariance was also found for ethnic status, with five thresholds of three items being higher for the minority participants. For depressive symptomatology, defined as the top quintile by the Beck Depression Inventory-II, partial scalar invariance required dropping one item, after which there were statistically significant differences only in two response thresholds. Overall, a wide range of PLE questionnaire items were found to be robust to gender and ethnicity effects, strengthening confidence in found group differences in PLEs. Although full scalar invariance could not be ascertained for any of the group comparisons, the few found scalar differences across groups were small, with minimal impact on group PLE estimates. However, since PLEs are easily conceptually entangled with depression symptoms, similar items should be considered for exclusion if separable constructs are the target of investigation.

Assessing cross-national invariance of the Community Assessment of Psychic Experiences (CAPE)

BACKGROUND

The Community Assessment of Psychic Experiences (CAPE) is a 42-item self-report questionnaire that has been developed and validated to measure the dimensions of psychosis in the general population. The CAPE has a three-factor structure with dimensions of positive, negative and depression. Assessing the cross-national equivalence of a questionnaire is an essential prerequisite before pooling data from different countries. In this study, our aim was to investigate the measurement invariance of the CAPE across different countries.

METHODS

Data were drawn from the European Union Gene-Environment Interaction (EU-GEI) study. Participants (incident cases of psychotic disorder, controls and siblings of cases) were recruited in Brazil, France, Italy, the Netherlands, Spain and UK. To analyse the measurement invariance across these samples, we tested configural invariance (i.e. identical structures of the factors), metric invariance (i.e. equivalence of the factor loadings) and scalar invariance (i.e. equivalence of the thresholds) of the three CAPE dimensions using multigroup categorical confirmatory factor analysis methods.

RESULTS

The configural invariance model fits well, providing evidence for identical factorial structure across countries. In comparison with the configural model invariance, the fit indices were very similar in the metric and scalar invariance models, indicating that factor loadings and thresholds did not differ across the six countries.

CONCLUSION

We found that, across six countries, the CAPE showed equivalent factorial structure, factor loadings and thresholds. Thus, differences observed in scores between individuals from different countries should be considered as reflecting different levels of psychosis.

Validation of the Spanish-language Cardiff Anomalous Perception Scale

The Cardiff Anomalous Perceptions Scale (CAPS) is a psychometric measure of hallucinatory experience. It has been widely used in English and used in initial studies in Spanish but a full validation study has not yet been published. We report a validation study of the Spanish-language CAPS, conducted in both Spain and Colombia to cover both European and Latin American Spanish. The Spanish-language version of the CAPS was produced through back translation with slight modifications made for local dialects. In Spain, 329 non-clinical participants completed the CAPS along with 40 patients with psychosis. In Colombia, 190 non-clinical participants completed the CAPS along with 21 patients with psychosis. Participants completed other psychometric scales measuring psychosis-like experience to additionally test convergent and divergent validity. The Spanish-language CAPS was found to have good internal reliability. Test-retest reliability was slightly below the cut-off, although could only be tested in the Spanish non-clinical sample. The scale showed solid construct validity and a principal components analysis broadly replicated previously reported three component factor structures for the CAPS.

Age moderates the association between frequent cannabis use and negative schizotypy over time

The current study examined whether age and frequent cannabis use interact to influence the trajectories of positive and negative schizotypy over time. Participants were 155 cannabis users, aged 15-24 years old, assessed over a 12-month period at 6-monthly intervals. The analyses examined the influence of age, frequent use, and time on positive and negative schizotypy. The current study found that among frequent cannabis users, younger age was associated with increased negative schizotypy over time, while among occasional cannabis users, younger age was associated with decreasing negative schizotypy over time. The current findings have implications for understanding how cannabis use may influence psychosis risk differently depending on age and frequency of use, as well as bring together past mixed findings on the relationship between negative schizotypy and cannabis use.

A reassessment of the higher-order factor structure of the German Schizotypal Personality Questionnaire (SPQ-G) in German-speaking adults

The Schizotypal Personality Questionnaire (SPQ) is a widely-used self-report instrument for the assessment of schizotypal personality traits. However, the factor structure of scores on English and non-English translations of the SPQ has been a matter of debate. With little previous factorial evaluation of the German version of the SPQ (SPQ-G), we re-assessed the higher-order factor structure of the measure. A total of 2,428 German-speaking adults from Central Europe (CE) and the United Kingdom (UK) completed the SPQ-G. Confirmatory factor analysis - testing proposed 2-, 3-, and 4-factor models of SPQ-G scores - indicated that the 4-factor solution had best fit. Partial measurement invariance across cultural group (CE and UK) and sex was obtained for the 4-factor model. Further analyses showed CE participants had significantly higher scores than UK participants on one schizotypal facet. These results suggest that scores on the SPQ-G are best explained in terms of a higher-order, 4-factor solution in German migrant and non-migrant adults.

The Network Structure of Schizotypal Personality Traits

Elucidating schizotypal traits is important if we are to understand the various manifestations of psychosis spectrum liability and to reliably identify individuals at high risk for psychosis. The present study examined the network structures of (1) 9 schizotypal personality domains and (2) 74 individual schizotypal items, and (3) explored whether networks differed across gender and culture (North America vs China). The study was conducted in a sample of 27001 participants from 12 countries and 21 sites (M age = 22.12; SD = 6.28; 37.5% males). The Schizotypal Personality Questionnaire (SPQ) was used to assess 74 self-report items aggregated in 9 domains. We used network models to estimate conditional dependence relations among variables. In the domain-level network, schizotypal traits were strongly interconnected. Predictability (explained variance of each node) ranged from 31% (odd/magical beliefs) to 55% (constricted affect), with a mean of 43.7%. In the item-level network, variables showed relations both within and across domains, although within-domain associations were generally stronger. The average predictability of SPQ items was 27.8%. The network structures of men and women were similar (r = .74), node centrality was similar across networks (r = .90), as was connectivity (195.59 and 199.70, respectively). North American and Chinese participants networks showed lower similarity in terms of structure (r = 0.44), node centrality (r = 0.56), and connectivity (180.35 and 153.97, respectively). In sum, the present article points to the value of conceptualizing schizotypal personality as a complex system of interacting cognitive, emotional, and affective characteristics.

Insomnia and intellect mask the positive link between schizotypal traits and creativity

Background

Schizotypy is a set of personality traits that resemble the signs and symptoms of schizophrenia in the general population, and it is associated with various subclinical mental health problems, including sleep disturbances. Additionally, dimensions of schizotypy show specific but weak associations with creativity. Given that creativity demands cognitive control and mental health, and that sleep disturbances negatively impact cognitive control, we predicted that positive, impulsive and disorganised schizotypy will demonstrate stronger associations with indicators of creativity, if the effect of mental health, insomnia, and intellect are statistically controlled.

Methods

University students (N = 182) took part in the study. Schizotypy was assessed with the shortened Oxford-Liverpool Inventory of Feelings and Experiences (sO-LIFE). Creative achievements were measured with the Creative Achievement Questionnaire (CAQ), divergent thinking was assessed with the ‘Just suppose’ task, and remote association problem solving was tested with Compound Remote Associate (CRA) problems. Mental health was assessed with the 12-item version of the General Health Questionnaire (GHQ-12), and insomnia was examined with the Athens Insomnia Scale (AIS). Verbal short term memory was measured with the forward digit span task, and intellect was assessed with the Rational-Experiential Inventory (REI). Multiple linear regressions were performed to examine the relationship between creativity and schizotypy. Indicators of creativity were the dependent variables. In the first block, dimensions of schizotypy, age, gender and smoking were entered, and in the second block, the models were extended with mental health, insomnia, verbal short term memory, and intellect.

Results

Positive schizotypy positively predicted real-life creative achievements, independently from the positive effect of intellect. Follow-up analyses revealed that positive schizotypy predicted creative achievements in art, while higher disorganised schizotypy was associated with creative achievements in science (when intellect was controlled for). Furthermore, disorganised schizotypy positively predicted remote association problem solving performance, if insomnia and verbal short term memory were statistically controlled. No dimension of schizotypy was significantly associated with divergent thinking.

Discussion

In line with previous findings, positive schizotypy predicted real-life creative achievements. The positive effects of disorganised schizotypy might be explained in terms of the simultaneous involvement of enhanced semantic priming and cognitive control in problem solving. We speculate that the lack of associations between divergent thinking and schizotypy might be related to instruction effects. Our study underscores the relevance of sleep impairment to the psychosis-spectrum, and refines our knowledge about the adaptive aspects of schizotypy in the general population.

Odd and disorganized-Comparing the factor structure of the three major schizotypy inventories

Schizotypy is a personality-framework currently considered a comprehensive and useful construct in schizophrenia research and becoming ever more accepted within psychiatry. Thus, it is crucial to obtain a unifying and generally accepted means of its measuring. The three most commonly used psychometric schizotypy inventories, the Wisconsin Schizotypy Scales, Schizotypal Personality Questionnaire and Oxford-Liverpool Inventory of Feelings and Experiences were, however, built upon different theoretical schizotypy models, wherefore comparing results from studies that have used different inventories is difficult and sometimes questionable. Therefore, an analysis of all three inventories was conducted within the same sample of 327 healthy participants to illustrate the similarities and differences in factor structures. Results showed that findings are likely dependent on the used assessment instrument. A following item-level factor analysis was conducted to investigate the shared structure of all three inventories, in order to illustrate a framework interpretable as "common ground" between measures. This adjusted four-factor structure may be used to better aid comparisons between schizotypy-studies having used different inventories. At least, our findings illustrate the necessity of viewing individual results before the background of the theoretical framework of the respective measurement tool.

Comparisons of schizotypal traits across 12 countries: Results from the International Consortium for Schizotypy Research

BACKGROUND

Schizotypal traits are expressions of underlying vulnerability to psychotic disorders which have a potential impact on mental health status, neurocognition, quality of life, and daily functioning. To date, little research has examined epidemiologic landscape of schizotypal traits at the cross-national level. Our aim was to study the expression of schizotypal traits by sex, age, and country in a combined sample gathered from 12 countries.

METHODS

A total of 27,001 participants completed the Schizotypal Personality Questionnaire (SPQ). The mean age of participants was 22.12 (SD=6.28); 37.5% (n=10,126) were males.

RESULTS

Schizotypal traits varied according to sex, age, and country. Females scored higher than males in the positive dimension, whereas males scored higher in the disorganization dimension. By age, a significant decrease in the positive schizotypal traits was observed. Epidemiological expression of schizotypal traits varied by country. Moreover, several interactions by sex, age, and country were found.

CONCLUSIONS

This pattern is similar to those found in patients with psychosis and psychotic-like experiences. These findings provide new insights and the opportunity to explore the phenotypic expression of schizotypal traits at cross-national level.

Psychiatric framing affects positive but not negative schizotypy scores in psychology and medical students

When testing risk for psychosis, we regularly rely on self-report questionnaires. Yet, the more that people know about this condition, the more they might respond defensively, in particular with regard to the more salient positive symptom dimension. In two studies, we investigated whether framing provided by questionnaire instructions might modulate responses on self-reported positive and negative schizotypy. The O-LIFE (UK study) or SPQ (New Zealand study) questionnaire was framed in either a "psychiatric", "creativity", or "personality" (NZ only) context. We tested psychology students (without taught knowledge about psychosis) and medical students (with taught knowledge about psychosis; UK only). We observed framing effects in psychology students in both studies: positive schizotypy scores were lower after the psychiatric compared to the creativity instruction. However, schizotypy scores did not differ between the creativity and personality framing conditions, suggesting that the low scores with psychiatric framing reflect defensive responding. The same framing effect was also observed in medical students, despite their lower positive schizotypy scores overall. Negative schizotypy scores were not affected by framing in either study. These results highlight the need to reduce response biases when studying schizotypy, because these might blur schizotypy-behaviour relationships.

Brief assessment of schizotypal traits: A multinational study

The Schizotypal Personality Questionnaire-Brief (SPQ-B) was developed with the aim of examining variations in healthy trait schizotypy, as well as latent vulnerability to psychotic-spectrum disorders. No previous study has studied the cross-cultural validity of the SPQ-B in a large cross-national sample. The main goal of the present study was to analyze the reliability and the internal structure of SPQ-B scores in a multinational sample of 28,426 participants recruited from 14 countries. The mean age was 22.63years (SD=7.08; range 16-68years), 37.7% (n=10,711) were men. The omega coefficients were high, ranging from 0.86 to 0.92 for the total sample. Confirmatory factor analysis revealed that SPQ-B items were grouped either in a theoretical structure of three first-order factors (Cognitive-Perceptual, Interpersonal, and Disorganized) or in a bifactor model (three first-order factors plus a general factor of schizotypal personality). In addition, the results supported configural but not strong measurement invariance of SPQ-B scores across samples. These findings provide new information about the factor structure of schizotypal personality, and support the validity and utility of the SPQ-B, a brief and easy tool for assessing self-reported schizotypal traits, in cross-national research. Theoretical and clinical implications for diagnostic systems, psychosis models, and cross-national mental health strategies are derived from these results.

The structure of schizotypal personality traits: a cross-national study

BACKGROUND

Schizotypal traits are considered a phenotypic-indicator of schizotypy, a latent personality organization reflecting a putative liability for psychosis. To date, no previous study has examined the comparability of factorial structures across samples originating from different countries and cultures. The main goal was to evaluate the factorial structure and reliability of the Schizotypal Personality Questionnaire (SPQ) scores by amalgamating data from studies conducted in 12 countries and across 21 sites.

METHOD

The overall sample consisted of 27 001 participants (37.5% males, n = 4251 drawn from the general population). The mean age was 22.12 years (s.d. = 6.28, range 16-55 years). The SPQ was used. Confirmatory factor analysis (CFA) and Multilevel CFA (ML-CFA) were used to evaluate the factor structure underlying the SPQ scores.

RESULTS

At the SPQ item level, the nine factor and second-order factor models showed adequate goodness-of-fit. At the SPQ subscale level, three- and four-factor models displayed better goodness-of-fit indices than other CFA models. ML-CFA showed that the intraclass correlation coefficients values were lower than 0.106. The three-factor model showed adequate goodness of fit indices in multilevel analysis. The ordinal α coefficients were high, ranging from 0.73 to 0.94 across individual samples, and from 0.84 to 0.91 for the combined sample.

CONCLUSIONS

The results are consistent with the conceptual notion that schizotypal personality is a multifaceted construct and support the validity and utility of SPQ in cross-cultural research. We discuss theoretical and clinical implications of our results for diagnostic systems, psychosis models and cross-national mental health strategies.

Dimensional Structure and Measurement Invariance of the Schizotypal Personality Questionnaire - Brief Revised (SPQ-BR) Scores Across American and Spanish Samples

The main goal of the present study was to test the measurement equivalence of the Schizotypal Personality Questionnaire - Brief Revised (SPQ-BR) scores in a large sample of Spanish and American non-clinical young adults. The sample was made up of 5,625 young adults (M = 19.65 years; SD = 2.53; 38.5% males). Study of the internal structure, using confirmatory factor analysis (CFA), revealed that SPQ-BR items were grouped in a theoretical internal structure of nine first-order factors. Moreover, three or four second-order factor and bifactor models showed adequate goodness-of-fit indices. Multigroup CFA showed that the nine lower-order factor models of the SPQ-BR had configural and weak measurement invariance and partial strong measurement invariance across country. The reliability of the SPQ-BR scores, estimated with omega, ranged from 0.67 to 0.91. Using the item response theory framework, the SPQ-BR provides more accurate information at the medium and high end of the latent trait. Statistically significant differences were found in the raw scores of the SPQ-BR subscales and dimensions across samples. The American group scored higher than the Spanish group in all SPQ-BR domains except Ideas of Reference and Suspiciousness. The finding of comparable factor structure in cross-cultural samples would lend further support to the continuum model of psychosis spectrum disorders. In addition, these results provide new information about the factor structure of schizotypal traits and support the validity and utility of this measure in cross-cultural research.