The stability of schizotypy across time and instruments

Measurement invariance of brief forms of the Schizotypal Personality Questionnaire across convenience versus random samples

Schizotypy, a multifaceted personality construct that represents liability for schizophrenia, is generally measured with self-report questionnaires that have been developed and validated in samples of undergraduate students. Given that understanding schizotypy in non-clinical samples is essential for furthering our understanding of schizophrenia-spectrum psychopathologies, it is critical to test whether non-clinically identified undergraduate and other convenience samples respond to schizotypy scales in the same way as random samples of the general population. Here, 651 undergraduates, 350 MTurk workers, and two randomly selected high school samples (n = 177, n = 551) completed brief versions of the Schizotypal Personality Questionnaire (SPQ-BR or SPQ-BRU). Multigroup confirmatory factor analysis was used to test whether measurement invariance was present across samples. Tests were made for all samples together and for each pair of samples. Results showed that a first-order nine-factor model fit the data well, and this factor structure displayed configural and metric invariance across the four samples. This suggests that schizotypy has the same factor structure, and the SPQ-BR/BRU is measuring the same construct across the different groups. However, when all groups were compared, results indicated a lack of scalar invariance across these samples, suggesting mean comparisons may be inappropriate across different sample types. However, when randomly selected high school students were compared with undergraduate students, scalar invariance was present. This suggests that factors such as culture and form type may be driving invariance, rather than sampling method (convenience vs general population).

Schizotypal traits in a large sample of high-school and university students from Tunisia: correlates and measurement invariance of the arabic schizotypal personality questionnaire across age and sex

BACKGROUND

The main goal of the present study was to examine the characteristics of schizotypal traits and their correlations with genetic (i.e., family history of mental illness), demographic (i.e., age, sex), environmental (e.g., income, urbanicity, tobacco/alcohol/cannabis use), and psychological (i.e., personal history of mental illness other than psychosis) factors in Tunisian high-school and university students. Our secondary goal was to contribute the literature by examining the factor structure and factorial invariance of the Arabic Schizotypal Personality Questionnaire (SPQ) across sex and age (adolescents [12-18 years] vs. young adults [18-35 years]) groups.

METHOD

This was a cross-sectional study involving 3166 students: 1160 (36.6%) high-school students (53.0% females, aged 14.9 ± 1.8); and 2006 (63.4%) university students (63.9% females, aged 21.8 ± 2.3). All students were asked to complete a paper-and-pencil self-administered questionnaire containing sociodemographic characteristics as well as the Arabic version of the SPQ.

RESULTS

The total sample yielded total SPQ scores of 24.1 ± 16.6 out of 74. The SPQ yielded good composite reliability as attested by McDonald's omega values ranging from .68 to .80 for all nine subscales. Confirmatory Factor Analysis indicated that fit of the 9-factor model of SPQ scores was acceptable. This model is invariant (at the configural, metric and structural levels) across sex and age. Except for "Odd or eccentric behavior", all schizotypy features were significantly higher among female students compared to males. Multivariable analyses showed that female sex, being a university student, lowest family incomes, tobacco use, and having a personal history of psychiatric illness were significantly associated with higher positive, negative and disorganized schizotypy subscales scores.

CONCLUSION

Future research still needs to confirm our findings and investigate the contribution of the identified factors in the development of clinical psychosis. We can also conclude that the Arabic SPQ is appropriate for measuring and comparing schizotypy across age and sex in clinical and research settings. These findings are highly relevant and essential for ensuring the clinical utility and applicability of the SPQ in cross-cultural research.

Polygenic risk for schizophrenia and schizotypal traits in non-clinical subjects

BACKGROUND

Schizotypy is a putative risk phenotype for psychosis liability, but the overlap of its genetic architecture with schizophrenia is poorly understood.

METHODS

We tested the hypothesis that dimensions of schizotypy (assessed with the SPQ-B) are associated with a polygenic risk score (PRS) for schizophrenia in a sample of 623 psychiatrically healthy, non-clinical subjects from the FOR2107 multi-centre study and a second sample of 1133 blood donors.

RESULTS

We did not find correlations of schizophrenia PRS with either overall SPQ or specific dimension scores, nor with adjusted schizotypy scores derived from the SPQ (addressing inter-scale variance). Also, PRS for affective disorders (bipolar disorder and major depression) were not significantly associated with schizotypy.

CONCLUSIONS

This important negative finding demonstrates that despite the hypothesised continuum of schizotypy and schizophrenia, schizotypy might share less genetic risk with schizophrenia than previously assumed (and possibly less compared to psychotic-like experiences).

Body structural representation in schizotypy

A deficient sense of self, typically observed in schizophrenia spectrum disorders, is often accompanied by abnormalities in bodily perception and awareness. These abnormalities are seemingly among the most powerful predictive factors for the onset of schizophrenic illnesses. According to the hypothesis of the psychosis continuum, high schizotypal traits in the general population may be characterized by a progressive sense of detachment from one's lived body. Building upon previous research that found an abnormal Body Structural Representation (BSR) in individuals with schizophrenia, this study aims to extend these findings to schizotypy. To investigate this, we utilized the Finger Localization Task (FLT), in which participants must identify the finger touched by the experimenter, and the In Between Task (IBT), in which two fingers are touched and participants must specify the number of fingers in between the two stimulated fingers. We found that individuals with high schizotypy were significantly less accurate than individuals with low schizotypy in determining the spatial configuration of their own fingers relative to each other. Most significantly, performances on both tasks were negatively correlated with the score on the Dissociative Experiences Scale (DES). These findings support the hypothesis that the progressive loss of one's sense of self is associated with abnormal bodily experiences and dissociative symptomatology which may represent a potential marker for schizophrenia proneness.

The Schizotypal Personality Questionnaire for Children (SPQ-C): Factor Structure, Child Abuse, and Family History of Schizotypy

There is a relative dearth of research on features of schizotypal personality in children, in part due to lack of instrumentation. This study tests 5 competing models of the factor structure of the self-report Schizotypal Personality Questionnaire for Children (SPQ-C) and examines its relationship with a family history of schizotypal personality disorder (SPD), child abuse, and stability over time. Hypotheses were tested on 454 11- to 12-year-old schoolchildren and their caregivers. Confirmatory factor analyses supported a 3-factor structure of the SPQ-C (cognitive-perceptual, interpersonal, and disorganized). Test-retest stability was relatively robust over 3 months (r = .67), 6 months (r = .64), and 12 months (r = .55), with acceptable internal reliabilities (r = .84 to .91). Regarding construct validity, children with a biological family history of SPD had higher scores on all 3 factors (d =.51). Abused children had higher schizotypy scores (d = .55). A genetic × environment interaction was observed, with schizotypy highest in those with both a family history of schizotypy and also child abuse. Findings are the first in the child schizotypy field to document a gene × environment interaction and the independence of child abuse from confounding genetic influences. Results support the utility of the SPQ-C in future family and clinical studies of schizotypal personality and provide an avenue for much-needed and neglected research into the early antecedents of child schizotypal personality.

Schizotypy but not Cannabis Use Modestly Predicts Psychotogenic Experiences: A Cross-Sectional Study Using the Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE)

Objective

Cannabis use predicts psychosis in longitudinal studies, but it is difficult to infer causation. Some precursor variables predict both, including childhood trauma and adversity. Additionally, some of the desired effects of cannabis use resemble the symptoms of psychosis. It would be preferable to assess psychotomimetic or “unusual” experiences that include psychotic symptoms but without assuming pathology. Finally, it is possible that similar people are prone to psychosis and drawn to cannabis use, perhaps, because they are sensitive or attracted to unusual experiences. Schizotypy provides a trait measure of proneness to unusual experiences. The study aimed to examine cross-sectionally relationships between cannabis use, schizotypy, and unusual experiences whilst controlling for current trauma symptoms.

Method

A volunteer online sample (n = 129, 64% women, predominantly students) who had used cannabis at least once was recruited. People who reported active effects of past trauma were excluded with a brief primary care posttraumatic stress disorder screen. Participants completed the Oxford-Liverpool Inventory of Feelings and Experience, the Cognitive Failures Questionnaire, and measures of substance use and sociodemographics.

Results

The majority of respondents recounted unusual experiences after cannabis use, and many of these might have been considered symptoms of psychosis if they had received medical attention. In regression analysis, the only predictor of the unusual experiences scale of O-LIFE was schizotypy (measured by the remaining subscales; 4% of variance). There were no correlations between cannabis use frequency and schizotypy or unusual experiences.

Conclusions

These findings suggest that, after controlling for schizotypy and excluding people who are actively experiencing the effects of past trauma, frequency of cannabis use does not predict unusual experiences. However, individuals with schizotypal personality traits may have more unusual experiences when using cannabis.

The association of striatal volume and positive schizotypy in healthy subjects: intelligence as a moderating factor

BACKGROUND

Schizotypy, a putative schizophrenia endophenotype, has been associated with brain-structural variations partly overlapping with those in psychotic disorders. Variations in precuneus structure have been repeatedly reported, whereas the involvement of fronto-striatal networks - as in schizophrenia - is less clear. While shared genetic architecture is thought to increase vulnerability to environmental insults, beneficial factors like general intelligence might buffer their effect.

METHODS

To further investigate the role of fronto-striatal networks in schizotypy, we examined the relationship of voxel- and surface-based brain morphometry and a measure of schizotypal traits (Schizotypal Personality Questionnaire, with subscores Cognitive-Perceptual, Interpersonal, Disorganised) in 115 healthy participants [54 female, mean age (s.d.) = 27.57(8.02)]. We tested intelligence (MWT-B) as a potential moderator.

RESULTS

We found a positive association of SPQ Cognitive-Perceptual with putamen volume (p = 0.040, FWE peak level-corrected), moderated by intelligence: with increasing IQ, the correlation of SPQ Cognitive-Perceptual and striatal volume decreased (p = 0.022). SPQ Disorganised was positively correlated with precentral volume (p = 0.013, FWE peak level-corrected). In an exploratory analysis (p < 0.001, uncorrected), SPQ total score was positively associated with gyrification in the precuneus and postcentral gyrus, and SPQ Disorganised was negatively associated with gyrification in the inferior frontal gyrus.

CONCLUSIONS

Our findings support the role of fronto-striatal networks for schizotypal features in healthy individuals, and suggest that these are influenced by buffering factors like intelligence. We conclude that protective factors, like general cognitive capacity, might attenuate the psychosis risk associated with schizotypy. These results endorse the idea of a continuous nature of schizotypy, mirroring similar findings in schizophrenia.

Cognitive Functioning and Schizotypy: A Four-Years Study

Although there is ample evidence from cross-sectional studies indicating cognitive deficits in high schizotypal individuals that resemble the cognitive profile of schizophrenia-spectrum patients, there is still lack of evidence by longitudinal/follow-up studies. The present study included assessments of schizotypal traits and a wide range of cognitive functions at two time points (baseline and 4-years assessments) in order to examine (a) their stability over time, (b) the predictive value of baseline schizotypy on cognition at follow-up and (c) differences in cognition between the two time points in high negative schizotypal and control individuals. Only high negative schizotypal individuals were compared with controls due to the limited number of participants falling in the other schizotypal groups at follow-up. Seventy participants (mean age: 36.17; 70% females) were assessed at baseline and follow-up. Schizotypal traits were evaluated with the Schizotypal Personality Questionnaire. We found that schizotypal traits decreased over time, except in a sub-group of participants ("schizotypy congruent") that includes individuals who consistently meet normative criteria of inclusion in either a schizotypal or control group. In these individuals, negative schizotypy and aspects of cognitive-perceptual and disorganized schizotypy remained stable. The stability of cognitive functioning also varied over time: response inhibition, aspects of cued attention switching, set-shifting and phonemic/semantic verbal fluency improved at follow-up. High negative schizotypy at baseline predicted poorer response inhibition and semantic switching at follow-up while high disorganized schizotypy predicted poorer semantic processing and complex processing speed/set-shifting. The between-group analyses revealed that response inhibition, set-shifting and complex processing speed/set-shifting were poorer in negative schizotypals compared with controls at both time points, while maintaining set and semantic switching were poorer only at follow-up. Taken together, the findings show differential stability of the schizotypal traits over time and indicate that different aspects of schizotypy predict a different pattern of neuropsychological task performance during a 4-years time window. These results are of significant use in the formulation of targeted early-intervention strategies for high-risk populations.

The Schizotypal Personality Questionnaire - Child (SPQ-C): Psychometric properties and relations to behavioral problems with multi-informant ratings

The Schizotypal Personality Questionnaire (SPQ) is one of the most widely used screening tools for schizotypy in adults. The Schizotypal Personality Questionnaire-Child version (SPQ-C) was recently developed to assess schizotypy in children and has a similar three-factor structure to the adult SPQ (i.e., Cognitive-Perceptual, Interpersonal-Affective, and Disorganization). However, few studies to date have reported on the psychometric properties and the usefulness of the SPQ-C in Eastern populations, including Mainland China. This study presents the first psychometric assessment of the Chinese SPQ-C in Mainland China. Exploratory factor analysis and confirmatory factor analysis were used to assess the factor structure of the SPQ-C in 1668 children (M = 12.10, SD = 0.60 years) from the China Jintan Child Cohort Study. Our findings document a three-factor structure and partial measurement invariance across residential location and gender, replicating the psychometric properties of the SPQ-C in English. The Chinese SPQ-C further correlates with standard behavioral problems (i.e., Child Behavior Checklist, Youth Self-Report and Teacher Report Form), demonstrating construct validity and utility as a child psychopathology assessment tool. Our findings provide the first robust psychometric evidence for a three-factor structure of the Chinese SPQ-C in a large Mainland Chinese sample, and suggest that the SPQ-C is suitable as a screening tool for schizotypy in community children who may be at risk for behavioral problems and later psychosis.

The effect of being left home alone at age 3 years on schizotypy and antisocial behavior at ages 17 and 23 years

OBJECTIVE

Negative home environments are associated with both schizophrenia-spectrum disorders and crime, but whether this is due to the social or cognitive sequelae of such environments is unclear. This study investigates the effect of early home environments on adult mental health.

METHOD

Using data from the Mauritius Child Health Project, a multiple time-point prospective study where all children born in 1969 in two towns (Quatre Bornes and Vacaos) were recruited at age 3 years (N = 1794), a group of children left home alone at age 3 (n = 34) were compared to children cared for by siblings/relatives (n = 222), or by mothers (n = 1498) on antisocial behavior and schizotypal personality at ages 11, 17, and 23 years.

RESULTS

Home alone children showed higher scores on psychotic behavior and conduct disorder at age 17, and also schizotypal personality and crime at 23 years compared to the other groups. No negative behavioral or cognitive effects were observed at age 11. Findings were not accounted for by social adversity or ethnicity and appear to be 'sleeper effects' in that they do not emerge until later adolescence and into adulthood.

CONCLUSIONS

Findings appear to be the first to show the negative effects of dual-parental daytime absence on adult schizotypy and crime, a finding that cannot be accounted for by verbal and spatial cognitive impairments. Results suggest an early common psychosocial denominator to the two comorbid conditions of antisocial behavior and schizotypy.

The factor structure of the short form of the Wisconsin schizotypy scales

The Chapman psychosis-proneness scales-also known as Wisconsin schizotypy scales (WSS)-are among the most used tools to measure schizotypy. The factor structure of the short-form WSS was investigated in a mixed sample of patients with chronic mental disorders and of healthy subjects from the general population. One hundred patients with a chronic mental disorder were enrolled over a 6-month period. For each patient, two controls of same sex and similar age (±5 years) were enrolled; 131 accepted to take part in the study. The unidimensional, the correlated four-factor, the second-order two-factor models, and the bifactor model with two or four orthogonally independent factors of the short-form WSS were tested with confirmatory factor analysis. Good reliability of the short-form WSS was confirmed, as its capacity of differentiating people with and without schizotypy. The bifactor models were superior to other models. However, in both bifactor models the explained common variance (ECV) attributable to the general factor and the percentage of uncontaminated correlations (PUC) were too low to use a general summary score as a measure of a single latent schizotypy variable. Symptoms scores derived from the short-form WSS can be better appreciated within a multidimensional model of schizotypy.

Developmental Aspects of Schizotypy and Suspiciousness: a Review

Purpose of the Review

This review identifies the early developmental processes that contribute to schizotypy and suspiciousness in adolescence and adulthood. It includes the most recent literature on these phenomena in childhood.

Recent Findings

The early developmental processes that affect schizotypy and paranoia in later life are complex. In contrast to existing studies of psychiatric patients and clinical/nonclinical adult populations, the study of schizotypy and suspiciousness in young children and adolescents is possible due to new child-appropriate dimensional assessments. New assessments and the advancement of technology (e.g., virtual reality in mental health) as well as statistical modeling (e.g., mediation and latent-class analyses) in large data have helped identified the developmental aspects (e.g., psychosocial, neurocognitive and brain factors, nutrition, and childhood correlates) that predict schizotypy and suspiciousness in later life.

Summary

Prospective longitudinal designs in community youths can enhance our understanding of the etiology of schizophrenia-spectrum disorders and, in the future, the development of preventive interventions by extending adult theories and interventions to younger populations.

The Factor Structure of the Schizotypal Personality Questionnaire in Undergraduate and Community Samples

The prevailing theoretical model of the Schizotypal Personality Questionnaire (SPQ) is a three-factor model based on subscale-level analyses. However, recent item-level factor analyses of the SPQ suggest a four- or five-factor model. To examine the factor structure of the SPQ and how this structure may differ between undergraduate and community samples, the authors conducted exploratory and confirmatory item-level factor analyses of this measure on undergraduate (N = 1,850) and community participants (N = 1,464). A clear three-factor solution was found in the community sample, whereas a somewhat equivocal four-factor solution was found in the undergraduate sample. Both structures displayed gender invariance. This is the first study to address the issues of undergraduate sample generalizability and gender invariance in an item-level exploratory factor analysis of the SPQ. Given the disparate findings in the samples, this study indicates the importance of using both community and undergraduate samples when examining the factor structure of the SPQ.