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).

Parental mental disorders and offspring schizotypy in middle childhood: an intergenerational record linkage study

PURPOSE

To investigate relationships between distinct schizotypy risk profiles in childhood and the full spectrum of parental mental disorders.

METHODS

Participants were 22,137 children drawn from the New South Wales Child Development Study, for whom profiles of risk for schizophrenia-spectrum disorders in middle childhood (age ~ 11 years) were derived in a previous study. A series of multinomial logistic regression analyses examined the likelihood of child membership in one of three schizotypy profiles (true schizotypy, introverted schizotypy, and affective schizotypy) relative to the children showing no risk, according to maternal and paternal diagnoses of seven types of mental disorders.

RESULTS

All types of parental mental disorders were associated with membership in all childhood schizotypy profiles. Children in the true schizotypy group were more than twice as likely as children in the no risk group to have a parent with any type of mental disorder (unadjusted odds ratio [OR] = 2.27, 95% confidence intervals [CI] = 2.01-2.56); those in the affective (OR = 1.54, 95% CI = 1.42-1.67) and introverted schizotypy profiles (OR = 1.39, 95% CI = 1.29-1.51) were also more likely to have been exposed to any parental mental disorder, relative to children showing no risk.

CONCLUSION

Childhood schizotypy risk profiles appear not to be related specifically to familial liability for schizophrenia-spectrum disorders; this is consistent with a model where liability for psychopathology is largely general rather than specific to particular diagnostic categories.

Longitudinal mediation by perceived burden of the pathway from thwarted belonging to suicidal ideation

INTRODUCTION

Whereas the interpersonal theory of suicide entails the assumption that thwarted belongingness and perceived burdensomeness are equally important, mutually moderating, proximal causes of active ideation, evidence suggests these may not be co-moderating processes. We tested an alternative perspective, hypothesizing that burden mediates the longitudinal relationship of thwarted belonging with active ideation.

METHODS

A 6-week, four-wave prospective online survey was completed by 298 undergraduates. We tested cross-sectional and cross-lagged panel models (CLPM, with and without random effects) with belonging, burden, and ideation at 2-week lags, and post hoc models with burden as a concurrent mediator of ideation.

RESULTS

Approximately 28% of undergraduates reported active ideation at baseline. Cross-sectionally, thwarted belonging had no direct influence on ideation but indirectly affected ideation via burden. This result was not confirmed in the 2-week CLPM analyses. In post hoc analyses, we found belonging operated indirectly via later burden to influence contemporaneous ideation.

CONCLUSIONS

Findings suggest thwarted belonging influences active ideation indirectly via perceived burden. The effect of burden as a mediator appears to depend on its temporal proximity to ideation. Future research should delimit the period during which perceived burden is an active mediator, accommodate dual-process approaches, and explore other mediation alternatives to co-moderation.

Developmental profiles of schizotypy in the general population: A record linkage study of Australian children aged 11-12 years

Objectives

The detection of young people at high risk for psychotic disorders has been somewhat narrowly focused on overt symptom‐based markers that reflect mild reality distortion (e.g., psychotic‐like experiences), or prodromal syndromes that are proximal to psychosis onset. The concept of schizotypy represents a broader framework for investigating risk for schizophrenia (and other disorders) in childhood, before the onset of prodromal or overt symptoms. We sought to detect profiles of risk for psychosis (schizotypy) in a general population sample of 22,137 Australian children aged 11–12 years, and to determine early life risk factors associated with these profiles from data available in linked records (registers).

Methods

Fifty‐nine self‐reported items were used as indicators of schizotypy across six broad domains; z‐scores for each domain were subjected to latent profile analyses (LPA). A series of multinomial logistic regressions was used to examine the association between resulting profile (class) membership and several childhood and parental risk factors, and the proportion of children with mental disorders among each schizotypy profile was examined.

Results

The LPA revealed three person‐centred profiles referred to as True Schizotypy (n = 1,323; 6.0%), Introverted Schizotypy (n = 4,473; 20.2%), and Affective Schizotypy (n = 4,261; 19.2%), as well as a group of children showing no risk (n = 12,080; 54.6%). Prior exposure to perinatal and familial adversities including childhood maltreatment, as well as poor early childhood development and academic functioning, was variously associated with all risk groups. There was a higher proportion of childhood mental disorder diagnoses among children in the True Schizotypy group, relative to other profiles.

Conclusion

Subtle differences in the pattern of exposures and antecedents among schizophrenia liability profiles in childhood may reflect distinct pathogenic pathways to psychotic or other mental illness.

Practitioner points

Children aged 11–12 years report characteristics of schizotypy which can be classified into three distinct profiles that may represent different pathological processes towards later mental ill‐health.

Early life exposure to perinatal and familial adversities including childhood maltreatment, early childhood developmental vulnerability, and poor academic functioning predict membership in all three childhood schizotypy profiles.

Latent liability for schizophrenia (and potentially other mental disorders) may be represented by different profiles of functioning observable in childhood.

Basic self-disturbance in schizotypy

AIM

Phenomenological researchers argue that schizophrenia spectrum disorders are primarily disorders of the basic self. To test this argument, we compared self-report and lexical measures of basic self-disturbance between schizophrenia spectrum (high-schizotypy) and non-spectrum groups (low-schizotypy).

METHODS

From an initial sample (n = 310) screened with the (SPQ), n = 39 were classified as high schizotypy (z > 1.28 on at least one SPQ factor scale) and were compared to a randomly selected low-schizotypy group (z < 1 on all three SPQ factor scales; n = 41). Participants wrote four narratives about personal and fictional experiences and completed the Ego Strength Questionnaire and a self-report version of the Schizophrenia Proneness Instrument. The written narratives were subjected to linguistic inquiry to examine pronoun usage (lexical measures).

RESULTS

The high-schizotypy group reported higher levels of basic symptoms, lower ego strength, and used third-person and personal pronouns more frequently than the low-schizotypy group. Self-report measures correlated significantly with lexical measures. Self-report and lexical measures were useful tools in predicting high schizotypy, correctly classifying 68% and 69% of schizotypy and non-schizotypy, respectively.

CONCLUSION

In line with phenomenologists' arguments, high schizotypy was associated, to some extent, with basic self-disturbance.

Aberrant salience and reward processing: a comparison of measures in schizophrenia and anxiety

BACKGROUND

Aberrant salience may contribute to the development of schizophrenia symptoms via alterations in reward processing and motivation. However, tests of this hypothesis have yielded inconsistent results. These inconsistencies may reflect problems with the validity and specificity of measures of aberrant salience in schizophrenia. Therefore, we investigated relationships among measures of aberrant salience, reward, and motivation in schizophrenia and anxiety.

METHOD

Individuals with schizophrenia (n = 30), anxiety (n = 33) or unaffected by mental disorder (n = 30) completed measures of aberrant salience [Aberrant Salience Inventory (ASI), Salience Attribution Test (SAT)], motivation (Effort Expenditure for Reward Task), and reinforcer sensitivity (Stimulus Chase Task).

RESULTS

Schizophrenia participants scored higher than anxiety (d = 0.71) and unaffected (d = 1.54) groups on the ASI and exhibited greater aberrant salience (d = 0.60) and lower adaptive salience (d = 0.98) than anxious participants on the SAT. There was no evidence of a correlation between measures of aberrant salience. Schizophrenia was associated with related deficits in motivated behaviour and maladaptive reward processing. However, these differences in reward processing did not correlate with aberrant salience measures.

CONCLUSIONS

The results suggest that key measures of aberrant salience have limited specificity and validity. These problems may account for inconsistent findings reported in the literature.

Psychotic Experiences and Schizotypy in Early Adolescence Predict Subsequent Suicidal Ideation Trajectories and Suicide Attempt Outcomes From Age 18 to 38 Years

Subclinical risk markers for schizophrenia predict suicidality, but little is known about the nature of the relationship. Suicidal ideation is often considered homogenous, but distinguishing passive from active ideation (ie, thoughts of death vs thoughts of killing oneself) and different temporal patterns may further the understanding of risk factors. We tested whether schizotypy and psychotic experiences (PEs) in early adolescence predict subsequent growth trajectories of suicidal ideation and suicide attempt outcomes. Participants were 1037 members of the population-representative Dunedin Study cohort. PE was measured at 11 years and schizotypy at 13 and 15 years. Outcomes were passive and active suicidal ideation, and suicide attempt, measured at 18, 21, 26, 32, and 38 years. Passive ideation was best represented by 2 trajectories, including persistent and transient ideation classes. Schizotypy predicted membership in the smaller persistent class (odds ratio [OR] = 1.21, P = .041), whereas PE was not associated with class membership. The probability of suicide attempts was 13.8% in the persistent ideation class, compared with 1.8% in the transient class. Active ideation was best represented by a 1-class model, the intercept of which was predicted by schizotypy (OR = 1.23, P = .015). Suicide attempts were predicted by schizotypy (OR = 1.53, P = .040) and PE (OR = 3.42, P = .046), and this was partially mediated by indirect effects via the active ideation trajectory. Findings indicate that adolescent schizotypy and PE are related to subsequent suicidal ideation and attempts. Suicidal ideation is heterogeneous, and schizotypy is specifically related to a persistent passive ideation subgroup.

Association of subclinical psychosis with suicidal ideation: A twin study

Subclinical psychosis, including schizotypal indicators and psychotic experiences, predicts future suicidal ideation. This relationship may reflect unmeasured confounding from environmental factors, genetic factors, or both. We used a genetically-informative twin design to understand if the association between subclinical psychosis and suicidal ideation is independent of shared genetic and environmental factors. We analysed cross-sectional associations of age-22 self-reported subclinical psychosis (positive, negative, and disorganised features) with suicidal ideation in twins participating in the FinnTwin12 study (maximum n = 1213). Then, we analysed the reverse association of age-14 suicidal ideation with age-22 subclinical psychosis. Associations were studied first among individuals and then within monozygotic (MZ) and dizygotic (DZ) pairs. Individual-level analyses showed that all subclinical psychosis factors were associated with suicidal ideation. In within-pair analyses, estimates of associations were lower for MZ pairs than DZ pairs, except for the negative schizotypy-suicidal ideation association where estimates were consistent across individual-level and within-pair analyses. Findings provide evidence that the association between negative features and suicide ideation is not explained by familial factors and may be causal, though the possibility of confounding by individual-specific environmental factors and reverse causation cannot be ruled out. The relationships of positive and disorganised subclinical psychosis features with suicidal ideation cannot be explained by confounding due to environmental factors shared between siblings, but their associations may be due to shared genetic factors.

Components of schizophrenia liability affect the growth of psychological stress sensitivity following major life events

BACKGROUND

Some argue that physiological and psychological stress sensitivities contribute causally to schizophrenia. Indeed, evidence shows that those with or at risk for schizophrenia have highly sensitive stress responses. However, it is unclear how psychological stress sensitivity develops. Our aim was to test whether psychological stress sensitization develops longitudinally in association with major life events and components of schizophrenia liability. We expected schizophrenia liability to predict higher psychological stress sensitivity; life events to predict subsequent increases in psychological stress sensitivity; and schizophrenia liability to moderate this relationship.

METHODS

In a prospective study, undergraduates (n = 184) completed a measure of schizophrenia liability at baseline. Then at 2-month intervals over 6 months, they reported on the occurrence of major life events and completed measures of psychological stress sensitivity.

RESULTS

Latent variable growth modelling showed that stress sensitivity increased following incident life events when controlling for baseline life events. Higher cognitive-perceptual and interpersonal scores predicted higher baseline sensitivity. Higher cognitive-perceptual features predicted larger increases in psychological stress sensitivity following life events whereas greater disorganization reduced growth.

CONCLUSIONS

This evidence is consistent with the idea that psychological sensitization is involved in the development of schizophrenia and suggests an important link between positive features of schizophrenia liability and the magnification of psychological stress sensitivity.

The relationships among aberrant salience, reward motivation, and reward sensitivity

OBJECTIVES

Change in reward processing and motivation may mediate the relationship between dopaminergic dysregulation and positive symptoms of schizophrenia. We sought to investigate the measurement of aberrant salience and its relationship with behavioural measures of reward and motivation.

METHODS

Participants (n = 82) completed measures of aberrant salience (Aberrant Salience Inventory and Salience Attribution Task), motivation (Effort Expenditure for Rewards Task), and reinforcer sensitivity (Stimulus Chase Task). Hypotheses were tested using correlation and generalised linear modelling.

RESULTS

Results indicated no relationship between aberrant salience measures. The Aberrant Salience Inventory was positively related to effort expenditure for lower less likely rewards and predicted the use of probability alone in decision-making. The only significant relationship between reward and motivation was a positive relationship between gain sensitivity and motivated behaviour for higher more likely rewards.

CONCLUSIONS

Although some support for a relationship between measures of reward motivation and aberrant salience were found, there was no evidence that the aberrant salience measures had concurrent validity. Our results suggest caution is warranted when interpreting measures of aberrant salience.

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.

Enhancing Psychosis-Spectrum Nosology Through an International Data Sharing Initiative

The latent structure of schizotypy and psychosis-spectrum symptoms remains poorly understood. Furthermore, molecular genetic substrates are poorly defined, largely due to the substantial resources required to collect rich phenotypic data across diverse populations. Sample sizes of phenotypic studies are often insufficient for advanced structural equation modeling approaches. In the last 50 years, efforts in both psychiatry and psychological science have moved toward (1) a dimensional model of psychopathology (eg, the current Hierarchical Taxonomy of Psychopathology [HiTOP] initiative), (2) an integration of methods and measures across traits and units of analysis (eg, the RDoC initiative), and (3) powerful, impactful study designs maximizing sample size to detect subtle genomic variation relating to complex traits (the Psychiatric Genomics Consortium [PGC]). These movements are important to the future study of the psychosis spectrum, and to resolving heterogeneity with respect to instrument and population. The International Consortium of Schizotypy Research is composed of over 40 laboratories in 12 countries, and to date, members have compiled a body of schizotypy- and psychosis-related phenotype data from more than 30000 individuals. It has become apparent that compiling data into a protected, relational database and crowdsourcing analytic and data science expertise will result in significant enhancement of current research on the structure and biological substrates of the psychosis spectrum. The authors present a data-sharing infrastructure similar to that of the PGC, and a resource-sharing infrastructure similar to that of HiTOP. This report details the rationale and benefits of the phenotypic data collective and presents an open invitation for participation.

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.

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 Latent Taxonicity of Schizotypy in Biological Siblings of Probands With Schizophrenia

If schizotypy is a taxonic liability for schizophrenia with a general population prevalence of ~10%, it should also be taxonic among biological siblings of probands with schizophrenia. Moreover, assuming this is so, siblings' schizotypy class membership should be predicted by probands' familial load for psychotic disorder and clinical severity, consistent with a multifactorial polygenic threshold model of schizophrenia. We tested these hypotheses in the Genetic Risk and Outcome of Psychosis (GROUP) Study where siblings of probands (n = 792) and unaffected controls (n = 559) provided self-report ratings on the Community Assessment of Psychic Experiences (CAPE). Maximum covariance analyses of control group ratings led to the identification of CAPE items sensitive to nonredundant positive and negative schizotypy classes in the control group (prevalence = 7.9% and 11.1%, respectively). When the same taxonic solution was applied to siblings' CAPE rating, taxometric analyses yielded evidence for larger positive and negative schizotypy classes among siblings (prevalence = 14.1% and 21.8%, respectively). Whereas probands' familial loads for bipolar disorder or drug use disorders did not predict siblings' membership in the schizotypy classes, probands' familial load for psychotic disorder did. Siblings were more likely to be members of the positive schizotypy class where their probands were more severely affected. The pattern of findings is consistent with Meehl's argument that schizotypy reflects liability for schizophrenia.

Intra-individual variability and psychotic-like experiences in adolescents: Findings from the ALSPAC cohort

Clinical and epidemiological studies have demonstrated associations between elevated intra-individual variability (IIV) of reaction time and psychotic disorders. However, little attention has been paid to the relationship between performance stability and psychotic-like experiences (PLE) in adolescence, before psychotic disorder onset. Data from 6702 children from the Avon Longitudinal Study of Parents and Children (ALSPAC) were used to address this issue. Children took part in a semi-structured clinical interview regarding psychotic symptoms at age 12 and 18, and reaction time variability was assessed at age 13 and 15. Children who had elevated IIV at age 15 were more likely to report suspected or definite PLE at age 18, with larger associations being found for more frequent or bizarre symptoms. Elevated IIV at age 15 was also associated with persistent PLE between age 12 and 18. These findings tentatively suggest that elevated IIV in early adolescence may be predictive of later PLE, and offer some support for the notion of a psychosis continuum.

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.

Testing the Validity of Taxonic Schizotypy Using Genetic and Environmental Risk Variables

BACKGROUND

Meehl regarded schizotypy as a categorial liability for schizophrenia that is the product of genes, environment, and gene-environment interactions. We sought to test whether schizophrenia-related genotypes and environmental risk factors predict membership in classes defined by taxometric analyses of positive (cognitive-perceptual), negative (interpersonal), and disorganized schizotypy.

METHODS

Participants (n = 500) completed the Schizotypal Personality Questionnaire (SPQ) and provided information on the following risk factors: cannabis use, pregnancy and obstetric complications, social adjustment, and family history of psychosis. Saliva samples were obtained so that the frequency of single-nucleotide polymorphism (SNP) alleles associated with risk for developing schizophrenia could be determined. Genotyped SNPs were rs1625579 (MIR137), rs7004633 (MMP16), rs7914558 (CNNM2), and rs12966547 (CCDC68). Sets of SPQ items were subject to multiple coherent cut kinetic (CCK) analyses, including mean-above-minus-below-a-cut, maximum covariance, maximum eigenvalue, and latent modes analyses.

RESULTS

CCK analyses indicated latent taxonicity of schizotypy across the 3 item sets. The cognitive-perceptual class had a base rate of 25%, and membership was predicted by the rs7004633 SNP (odds ratio = 2.33, 95% confidence interval = 1.15-4.72 in adjusted analyses). Poor social adjustment predicted memberships in the interpersonal (16%) and disorganized (21%) classes. Classes were found not to be mutually exclusive.

CONCLUSIONS

Schizotypy is taxonic and schizotypy class membership is predicted by genetic and environmental factors that predict schizophrenia. The findings hold the promise that a more complete understanding of schizotypy as a schizophrenia liability state will come from investigation of other genes and environmental factors associated with schizophrenia.

Preliminary evidence that schizophrenia liability at age 15 predicts suicidal ideation two years later

We tested artifactual and theory-based accounts of the relationship between schizophrenia liability and suicidality. At baseline, 387 adolescents (12 to 17years) completed measures of schizotypy, hopelessness, and depressed affect. After two years, schizotypal and non-schizotypal subsamples (n=16 and 31, respectively) self-reported passive suicidal ideation, active ideation, and serious ideation and action. Taxonic schizotypy predicted passive ideation (OR=8.15, 95% CI 1.34, 49.60) even when controlling for depressed affect. Hopelessness did not predict suicidality or moderate schizotypy-suicidality relationships. Findings were consistent with the interpersonal theory of suicide and contrary to the artifactual account of the association.

Paternal and maternal ages have contrasting associations with self-reported schizophrenia liability

BACKGROUND

Older paternal age predicts schizophrenia diagnosis in offspring. If this relationship reflects a pathogenic process, paternal age should predict the expression of subclinical schizophrenia liability (schizotypy). We hypothesized that paternal and maternal ages predict positive, negative, and disorganized features of schizotypy, that family history of psychosis moderates the relationship of paternal age with schizotypy, and that stress sensitivity mediates the relationship of maternal age with schizotypy.

METHOD

Two studies are reported, each of undergraduates (n=500 and n=211) who completed the Schizotypal Personality Questionnaire. The second was designed to replicate and extend the first and included assessment of stress sensitivity.

RESULTS

In Study 1, older paternal age and younger maternal age predicted greater positive schizotypy (β=.13 and β=-.19, respectively). Parental ages did not predict negative or disorganized features and family history did not moderate the paternal age association. In Study 2, the same pattern of associations between parental ages and schizotypy components was observed. Additionally, stress sensitivity partially mediated the association of maternal age with positive schizotypy whereas it did not contribute to the paternal age association.

CONCLUSION

The association between older paternal age and schizophrenia extends to self-reported positive features of schizophrenia liability, consistent with the notion that this relationship arises from a pathogenic process, such as de novo mutations. Importantly, younger maternal age was an equally potent predictor of positive schizotypy, with its association partially mediated by stress sensitivity.

Dimensionality vs taxonicity of schizotypy: some new data and challenges ahead

Heterogeneity in the expression of schizotypy may arise from underlying dimensional processes or a taxonic population structure. In a 2-phase study, we tested the taxonicity of self-reported schizotypy within a general psychiatric sample (n = 109) and examined taxon validity by testing its association with clinical schizotaxia in follow-up subsamples. Taxometric analyses indicated a taxonic structure (schizotypy prevalence = 38.8%) provided the best description of the underlying population distribution. After a year, schizotypal (n = 14) and nonschizotypal (n = 14) subsamples returned for diagnosis of clinical schizotaxia by assessment of executive functioning, attention, memory, and negative symptoms. Seven patients met diagnostic criteria, all members of the schizotypy class. Schizotypy was associated with impaired attention and memory, more negative symptoms, poorer global functioning, and more extensive psychiatric histories. We reconcile inconsistencies in the literature by discussing threats to the validity of this and similar research on Meehl's taxonomic model of schizotypy, including conceptual limitations of the lexical hypothesis and conventions of factor analysis. Scrutiny of Meehl's model should involve disambiguation and better measurement of the schizotaxia-schizotypy phenotype.

The taxonicity of schizotypy: does the same taxonic class structure emerge from analyses of different attributes of schizotypy and from fundamentally different statistical methods?

Findings on the population distribution of schizotypy consistently point toward an underlying class structure. However, past research is methodologically homogeneous, chiefly involving analysis of attribute-specific indicators and coherent cut kinetic methods such as maximum covariance (MAXCOV) analysis. Two questions are examined. Are different or overlapping classes identified from different attributes of the schizophrenia phenotype? Do fundamentally different approaches to analysis yield consistent results? Participants (n=1074) completed the Schizotypal Personality Questionnaire (SPQ). Following item screening, MAXCOV analyses were conducted iteratively on attribute-specific item sets (cognitive-perceptual, interpersonal, and disorganized) and a general item set. Latent variable modeling (factor analysis, latent class analysis, and factor-mixture modeling) was used to examine the consistency of the MAXCOV results using items retained in the general set following MAXCOV analysis. Attribute-specific and general item sets gave taxonic MAXCOV curves and base rates of 8.4-10.4% and 3.6%, respectively. Classes were not independent. No latent variable model emerged as uniquely superior but five models distinguished a small high-scoring class populated by members of the MAXCOV general class. Different attributes distinguished overlapping yet nonredundant taxa, and a general schizotypy taxon identified with MAXCOV was also identified in latent variable modeling.

An updated and conservative systematic review and meta-analysis of epidemiological evidence on psychotic experiences in children and adults: on the pathway from proneness to persistence to dimensional expression across mental disorders

BACKGROUND

The psychosis-proneness-persistence-impairment model of psychotic disorder incorporates notions of both phenomenological and temporal continuity (persistence) of psychotic experiences (PE), but not structural continuity. Specific testable propositions of phenomenological continuity and persistence are identified. Method Propositions are tested by systematic reviews of the epidemiology of PE, persistence of PE and disorder outcomes, and meta-analyses (including Monte Carlo permutation sampling, MCPS) of reported rates and odds ratios (ORs).

RESULTS

Estimates of the incidence and prevalence of PE obtained from 61 cohorts revealed a median annual incidence of 2.5% and a prevalence of 7.2%. Meta-analysis of risk factors identified age, minority or migrant status, income, education, employment, marital status, alcohol use, cannabis use, stress, urbanicity and family history of mental illness as important predictors of PE. The mode of assessment accounted for significant variance in the observed rates. Across cohorts, the probability of persistence was very strongly related to the rate of PE at baseline. Of those who report PE, ∼20% go on to experience persistent PE whereas for ∼80%, PE remit over time. Of those with baseline PE, 7.4% develop a psychotic disorder outcome.

CONCLUSIONS

Compelling support is found for the phenomenological and temporal continuity between PE and psychotic disorder and for the fundamental proposition that this relationship is probabilistic. However, imprecision in epidemiological research design, measurement limitations and the epiphenomenological nature of PE invite further robust scrutiny of the continuity theory.

Systematic reviews of categorical versus continuum models in psychosis: evidence for discontinuous subpopulations underlying a psychometric continuum. Implications for DSM-V, DSM-VI, and DSM-VII

Diagnostic systems, phenotype models, and theories of etiology incorporate propositions on the underlying nature of psychosis and schizophrenia phenotypes. These propositions, whether implicit or explicit, are that the distributions of the phenotypes, or the phenotype experiences themselves, are dimensional or categorical. On one hand, evidence on the epidemiology of schizophrenia phenotypes suggests symptom phenotypes may not be bound by conventional diagnostic thresholds but instead may blend imperceptibly with subclinical, statistically frequent experience, supporting continuum viewpoints. On the other hand, evidence on the population structure suggests a latent categorical structure; the population may be composed of two types of people. However, both sets of evidence are beset by methodological limitations that point unequivocally to the need to move beyond current diagnostic conceptualizations, observation, and anamnesis of psychosis, and toward responsive and scientifically refutable formulations of schizophrenia.

Seeking verisimilitude in a class: a systematic review of evidence that the criterial clinical symptoms of schizophrenia are taxonic

This review examines whether there is evidence that the criterion symptoms of Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) (DSM-IV) schizophrenia are taxonic--that schizophrenia is not part of a single distribution of normality. Two taxometric methods, coherent cut kinetics (CCK) and latent variable modeling (LVM), are demonstrated to be sensitive to latent classes and, therefore, were regarded as providing relevant statistical evidence. A systematic literature search identified 24 articles describing analyses of 28 participant cohorts in which CCK or LVM methods were used with one or more criterion symptoms of schizophrenia. Virtually all analyses yielded results that, on first impression, favored taxonic over dimensional interpretations of the latent structure of schizophrenia. However, threats to the internal and external validity of these studies--including biased or inadequate analyses, violation of statistical assumptions, inadequate indicator screening, and the introduction of systematic error through recruitment and sampling--critically undermine this body of work. Uncertainties about the potential effects of perceptual biases, unimodal assessment, and item parceling are also identified, as are limitations in seeking to validate classes with single or double dissociations of outcomes. We conclude that there is no reason to seriously doubt a single-distribution model of schizophrenia because there is no evidence that provides a serious test of this null hypothesis. A second fundamental question remains outstanding: is schizophrenia truly a group of schizophrenias, with taxonic divisions separating its types? We make design and analysis suggestions for future research addressing these questions.

The burden of awareness of psychometric risk for schizophrenia

Participants in studies of psychometric risk for schizophrenia are rarely informed of their risk status. Nondisclosure may be justifiable if the harmful effects of disclosure outweigh its benefits. We examined whether disclosure may adversely affect well-being and, if so, factors that predict the degree of adverse effect. Undergraduates (n=114) rated the anticipated impact--on felt distress, coping, optimism, helplessness, future lifestyle choices, and survival--of discovering they were at risk for schizophrenia and six other diseases. They also completed measures of potential predictors of this impact, including knowledge about schizophrenia, vicarious experience of schizophrenia, their potential to suffer stigmatization because of schizophrenia, and schizotypy. Participants judged schizophrenia risk more negatively than risk for heart disease, arthritis, depression, and diabetes, and less negatively than risk for cancer and Alzheimer's disease. Higher disorder-nonspecific impact, greater stigma, and lower psychometric risk for schizophrenia together provided the best linear prediction of schizophrenia-specific impact. Awareness of schizophrenia risk creates a significant adverse impact, the level of which may be greatest among those with lowest risk.

A systematic review and meta-analysis of the psychosis continuum: evidence for a psychosis proneness-persistence-impairment model of psychotic disorder

A systematic review of all reported incidence and prevalence studies of population rates of subclinical psychotic experiences reveals a median prevalence rate of around 5% and a median incidence rate of around 3%. A meta-analysis of risk factors reveals associations with developmental stage, child and adult social adversity, psychoactive drug use, and also male sex and migrant status. The small difference between prevalence and incidence rates, together with data from follow-up studies, indicates that approximately 75-90% of developmental psychotic experiences are transitory and disappear over time. There is evidence, however, that transitory developmental expression of psychosis (psychosis proneness) may become abnormally persistent (persistence) and subsequently clinically relevant (impairment), depending on the degree of environmental risk the person is additionally exposed to. The psychosis proneness-persistence-impairment model considers genetic background factors impacting on a broadly distributed and transitory population expression of psychosis during development, poor prognosis of which, in terms of persistence and clinical need, is predicted by environmental exposure interacting with genetic risk.

The latent structure and coincidence of hypohedonia and schizotypy and their validity as indices of psychometric risk for schizophrenia

Recent exchanges on the place of hypohedonia within Meehl's theory of schizotaxia, schizotypy, and schizophrenia focus on evidence of the taxonicity of asociality, not hedonic capacity per se. Two hypotheses were contrasted, one that hypohedonia is a nonpathological individual difference variable independent of schizotypy, the other that schizotypy and hypohedonia tap independent taxonic processes that predict the emergence of positive and negative signs of schizophrenia, respectively. Undergraduates (n = 1,543) completed a multifaceted measure of schizotypy and hypohedonia. A consecutive subsample of these (n = 284) also completed a continuous performance test and the Symptom Checklist 90-Revised. Independent taxometric analyses (maximum covariance and maximum eigenvalue) indicated schizotypy was taxonic and hypohedonia was dimensional. Their coincidence was no greater than chance. Schizotypy was associated with impaired attention and significant psychological distress, whereas hypohedonia was not. Hypohedonia does not behave like a core component of schizotypy.

Over-representation of Maori New Zealanders among adolescents in a schizotypy taxon

BACKGROUND

Minority ethnic and migrant groups are often over-represented among those with schizophrenia.

OBJECTIVES

The aim of this study was to determine whether Maori, the aboriginal minority of New Zealand, are over-represented in a schizotypy taxon derived from a general population sample of adolescents.

METHOD

Secondary school students (n = 387) aged 13 to 17 years completed self-report measures of four schizotypy attributes, magical thinking, hallucinatory tendency, self-referential ideation, and perceptual aberration, and indicated ethnic descent and self-identified ethnic belonging.

RESULTS

Taxometric analyses (maximum covariance, maximum eigenvalue, latent modes) yielded consistent evidence of taxonicity of schizotypy. Participants who were of Maori descent were over-represented in the schizotypy group.

CONCLUSIONS

Ethnicity, or the stress and resilience factors for which ethnicity is a proxy measure, has a measurable impact on psychometric risk for schizophrenia.

Thought disorder, pragmatic language impairment, and generalized cognitive decline in schizophrenia

BACKGROUND

Schizophrenia is associated with pragmatic language impairment (PLI), a reduced ability to communicate intention in a rule-governed fashion. Two explanations for PLI include that PLI is equivalent to thought disorder and that PLI is secondary to generalized cognitive decline.

OBJECTIVES

The aims of this study were to demonstrate PLI in schizophrenia and to test which of these explanations best accounts for the relationships among thought disorder, PLI, and generalized cognitive decline.

METHOD

Schizophrenia (n=20) and control (n=26) participants provided speech samples that were scored for thought disorder (type-token ratio and Cloze procedure) and PLI [Profile of Pragmatic Impairment in Communication (PPIC)]. Generalized cognitive decline was determined from discrepancies between current and premorbid verbal IQ.

RESULTS

Patients with schizophrenia exhibited significant PLI and generalized cognitive decline. There was no evidence of an association between thought disorder and PLI. Moreover, generalized cognitive decline predicted PLI (r(2)=0.33 to 0.59) but not thought disorder (r(2)=0.02 to 0.06).

CONCLUSIONS

The results conformed to a predicted pattern of associations based on the notion that PLI in schizophrenia is secondary to generalized cognitive decline.

Automatic hypermnesia and impaired recollection in schizophrenia

Evidence from studies of nonmnemonic automatic cognitive processes provides reason to expect that schizophrenia is associated with exaggerated automatic memory (implicit memory), or automatic hypermnesia. Participants with schizophrenia (n = 22) and control participants (n = 26) were compared on word stem completion (WSC) and list discrimination (LD) tasks administered using the process dissociation procedure. Unadjusted, extended measurement model and dual-process signal-detection methods were used to estimate recollection and automatic memory indices. Schizophrenia was associated with automatic hypermnesia on the WSC task and impaired recollection on both tasks. Thought disorder was associated with even greater automatic hypermnesia. The absence of automatic hypermnesia on the LD task was interpreted with reference to the neuropsychological bases of context and content memory.

Automatic hypermnesia and impaired recollection in schizophrenia

Evidence from studies of nonmnemonic automatic cognitive processes provides reason to expect that schizophrenia is associated with exaggerated automatic memory (implicit memory), or automatic hypermnesia. Participants with schizophrenia (n = 22) and control participants (n = 26) were compared on word stem completion (WSC) and list discrimination (LD) tasks administered using the process dissociation procedure. Unadjusted, extended measurement model and dual-process signal-detection methods were used to estimate recollection and automatic memory indices. Schizophrenia was associated with automatic hypermnesia on the WSC task and impaired recollection on both tasks. Thought disorder was associated with even greater automatic hypermnesia. The absence of automatic hypermnesia on the LD task was interpreted with reference to the neuropsychological bases of context and content memory.

The Profile of Functional Impairment in Communication (PFIC): a measure of communication impairment for clinical use

This article describes the construction of the Profile of Functional Impairment in Communication (PFIC), a scale designed for the assessment of communication impairments following traumatic brain injury. The measure comprises 10 feature summary scales, assessing severity of impairment, and 84 specific behaviour items, assessing the frequency of specific communication impairments. To assess the psychometric properties of the scale, videotaped dyadic social interactions of 20 patients with traumatic brain injury were rated by eight trained raters. The feature summary scales were found to have acceptable inter-rater reliabilities, and high concurrent validity and internal consistency. Four case descriptions are presented to illustrate the clinical application of the PFIC. It is concluded that the PFIC is a useful measure for the identification of specific communication impairments in clinical practice.