Development of a version of the Schizotypy Traits Questionnaire (STA) for screening children

A new scale for the screening of childhood early psychotic symptoms

This study aimed to develop a new scale, the Early Psychotic Symptoms screening scale (EPSy), to assess the prodromes of psychotic symptoms in children aged 4 to 13 years. Two versions were proposed: one to assess the child's current behavior and one to assess the child's behavior when he/she was 2 years old. The second aim of this study was to investigate the presence of these symptoms at the age of 2 years and their evolution up to the child's current age. The analysis of EPSy identified three main factors, namely mistrust/paranoia, perceptual aberrations/hallucinations and disorganized symptoms. It has good psychometric properties. Data also shows that, independently of the participant's age, the total score on the 2-years-old version predicts the total score on the current-age version, and this is also the case for each individual factor. Finally, it is of clinical interest since it makes it possible to describe symptomatology both at age 2 and at the child's present age depending on the group to which the children are assigned (control children, psychotic children, non-psychotic children).

Genetic and Geographical Associations With Six Dimensions of Psychotic Experiences in Adolesence

BACKGROUND AND HYPOTHESIS

Large-scale epidemiological and genetic research have shown that psychotic experiences in the community are risk factors for adverse physical and psychiatric outcomes. We investigated the associations of six types of specific psychotic experiences and negative symptoms assessed in mid-adolescence with well-established environmental and genetic risk factors for psychosis.

STUDY DESIGN

Fourteen polygenic risk scores (PRS) and nine geographical environmental variables from 3590 participants of the Twins Early Development Study (mean age 16) were associated with paranoia, hallucinations, cognitive disorganization, grandiosity, anhedonia, and negative symptoms scales. The predictors were modeled using LASSO regularization separately (Genetic and Environmental models) and jointly (GE model).

STUDY RESULTS

In joint GE models, we found significant genetic associations of negative symptoms with educational attainment PRS (β = -.07; 95% CI = -0.12 to -0.04); cognitive disorganization with neuroticism PRS (β = .05; 95% CI = 0.03-0.08); paranoia with MDD (β = .07; 95% CI = 0.04-0.1), BMI (β = .05; 95% CI = 0.02-0.08), and neuroticism PRS (β = .05; 95% CI = 0.02-0.08). From the environmental measures only family SES (β = -.07, 95% CI = -0.10 to -0.03) and regional education levels (β = -.06; 95% CI = -0.09 to -0.02) were associated with negative symptoms.

CONCLUSIONS

Our findings advance understanding of how genetic propensity for psychiatric, cognitive, and anthropometric traits, as well as environmental factors, together play a role in creating vulnerability for specific psychotic experiences and negative symptoms in mid-adolescence.

Prevalence and Correlates of Psychotic Like Experiences in a Large Community Sample of Young Adults in Tunisia

Despite the increased focus on non-clinical psychosis populations, no community surveys have properly investigated the phenotypal expression of Psychotic like experiences (PLEs) in the Arab-Muslim world. We aimed to examine the prevalence and correlates of PLEs in a large sample of Tunisian college students. A total of 1489 students (64.3% female, aged 18-40) participated in a cross-sectional survey. The Positive Subscale of Community Assessment of Psychotic Experiences was used to measure PLEs. The rates of PLEs found in our work were relatively high compared with those found in previous international studies, with 51.4% of the participants reporting at least one positive PLE 'nearly-always'. After controling for confounding variables, other drug use in the past year represented the only substance use variable among the significant predictors in the final model. Our findings should raise awareness of the need for implementing an early intervention programs in our region.

Childhood sexual abuse as a potential predictor of psychotic like experiences in Tunisian college students

BACKGROUND

Current research has shown that experiencing childhood trauma may predispose individuals for psychosis and expression of Psychotic like experiences (PLEs). We aimed to examine the prevalence and characteristics of PLEs and depressive and negative experiences in a sample of Tunisian college students, and to evaluate the impact of childhood traumas in the occurrence and severity of these experiences at the time of the survey.

METHOD

A total of 482 college students (63.7% female; aged 18-32) participated in a cross-sectional survey. The Positive Subscale of Community Assessment of Psychotic Experiences (CAPE) was used to measure PLEs. The Childhood Trauma Questionnaire was used to assess childhood trauma and neglect.

RESULTS

53.5% (n = 258) of the students reported at least one positive PLE 'nearly always', and 40.9% (n = 197) reported at least one negative PLE with this frequency. After controlling for demographic variables (gender, age) and psychosocial factors (drug use, depression, anxiety and stress), sexual abuse significantly contributed to PLEs.

CONCLUSION

There is a need for further cross-cultural research regarding the phenotypal expression of PLEs and its associated variables. Child sexual abuse victims should receive systematic and complete psychological screening during their adolescence/ early adulthood including, among others, PLEs and psychotic symptoms.

Dimensional assessment of schizotypal, psychotic, and other psychiatric traits in children and their parents: development and validation of the Childhood Oxford-Liverpool Inventory of Feelings and Experiences on a representative US sample

BACKGROUND

Healthy functioning relies on a variety of perceptual, cognitive, emotional, and behavioral abilities that are distributed throughout the normal population. Variation in these traits define the wide range of neurodevelopmental (NDD) and neuropsychiatric (NPD) disorders. Here, we introduce a new measure for assessing these traits in typically developing children and children at risk for NDD and NPD from age 2 to 18 years.

METHOD

The Childhood Oxford-Liverpool Inventory of Feelings and Experiences (CO-LIFE) was created as a dimensional, parent-report measure of schizotypal and psychotic traits in the general population. Parents of 2,786 children also self-reported on an adapted version of the Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE-US).

RESULTS

The CO-LIFE resulted in continuous distributions for the total score and for each of three factor analytically-derived subscales. Item response theory (IRT) analyses indicated strong reliability across the score range for the O-LIFE-US and the CO-LIFE. Internal consistency and test-retest reliability were high across all scales. Parent-child intraclass correlations were consistent with high heritability. The scales discriminated participants who reported a lifetime psychiatric diagnosis from those who reported no diagnosis. The O-LIFE-US and CO-LIFE scores correlated positively with the Social Responsiveness Scale 2 (SRS-2) indicating good convergent validity.

CONCLUSIONS

Like the original O-LIFE, the O-LIFE-US and the CO-LIFE are valid and reliable tools that reflect the spectrum of psychiatric and schizotypal traits in the general population. Such scales are necessary for conducting family studies that aim to examine a range of psychological and behavioral traits in both children and adults and are well-suited for the Research Domain Criteria (RDoC) initiative of the NIMH.

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

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

Development of Embodied Sense of Self Scale (ESSS): Exploring Everyday Experiences Induced by Anomalous Self-Representation

The scientific exploration of the self has progressed, with much attention focused on the Embodied Sense of Self (ESS). Empirical studies have suggested the mechanisms for self-representation. On the other hand, less attention has been paid to the subjectivity itself of the self. With reference to previous studies, the current study collected items that reflect the ESS and statistically extracted three factors for it: Ownership, Agency, and Narrative. The developed questionnaire [Embodied Sense of Self Scale (ESSS)] showed good enough validity and reliability for practical use. Furthermore, ESSS discriminated schizophrenia, a disorder of the ESS, from controls. We discuss the factorial structure of ESS and the relationship among factors on the basis of the current results.

The validity of the Schizotypal Personality Questionnaire in a Greek sample: Tests of measurement invariance and latent mean differences

BACKGROUND

The Schizotypal Personality Questionnaire (SPQ) is a widely used scale for measuring schizotypal characteristics modeled on DSM-III-R criteria for schizotypal personality disorder (SPD). The aim of this study was to examine the factorial structure of the Greek SPQ, its factorial invariance across gender and different age groups and possible gender and age group differences at latent mean level.

METHODS

Eight hundred sixty-five community participants completed the Greek version of the SPQ.

RESULTS

With regard to the factorial structure of the original first-order model, the results showed that a seven-factor model (sub-scales "no close friends" with "constricted affect" and "ideas of reference" with "unusual perceptual experiences" were combined) was replicated adequately. Furthermore, the second-order "paranoid" model provided also adequate fit. With regard to the factorial invariance of the SPQ across gender and age, the analysis revealed that both, the first- and second-order models showed measurement invariance (configural, metric and structural) across gender and age groups (17-35 vs. 36-70). Latent mean differences across gender and age groups were also found.

CONCLUSIONS

Based on these findings, we can conclude that the Greek version of the SPQ is a psychometrically sound instrument for measuring schizotypal characteristics and a useful screening tool for SPD across gender and age.

Reliability and normative data of the Perceptual Aberration Scale in an Italian juvenile general population sample

Psychometric tools, such as the Perceptual Aberration Scale (PAS), have been developed to identify people at risk to develop psychosis. This paper aims at providing an Italian version of the Perceptual Aberration Scale and its normative data for the general juvenile Italian population. The Italian version of the PAS was produced using three independent translators. It was administered to 1089 non-clinical participants, stratified into three age-groups, i.e., 8-13, 14-17 and 18-24. The Italian version of the PAS displayed good internal consistency in each age-group evaluated (i.e. Alpha Coefficients: 0.90 for the 8-13 age-group, 0.84 for the 14-17 age-group, and 0.87 for the 18-24 age-group) and the assumption of unidimensionality was corraborate. Furthermore, normative data for the three groups were collected (i.e. cut-offs: 25 for the 8-13 age-group, 21 for the 14-17 age-group and 20 for the 18-24 age-group) and an age-related difference, as the 18-24 group scored lower than the younger groups, was found. The Italian version of the PAS proved to be a reliable psychometric tool to investigate perceptual aberration during childhood, adolescence and young adulthood.

Heritability of Individual Psychotic Experiences Captured by Common Genetic Variants in a Community Sample of Adolescents

Occurrence of psychotic experiences is common amongst adolescents in the general population. Twin studies suggest that a third to a half of variance in adolescent psychotic experiences is explained by genetic influences. Here we test the extent to which common genetic variants account for some of the twin-based heritability. Psychotic experiences were assessed with the Specific Psychotic Experiences Questionnaire in a community sample of 2152 16-year-olds. Self-reported measures of Paranoia, Hallucinations, Cognitive Disorganization, Grandiosity, Anhedonia, and Parent-rated Negative Symptoms were obtained. Estimates of SNP heritability were derived and compared to the twin heritability estimates from the same sample. Three approaches to genome-wide restricted maximum likelihood (GREML) analyses were compared: (1) standard GREML performed on full genome-wide data; (2) GREML stratified by minor allele frequency (MAF); and (3) GREML performed on pruned data. The standard GREML revealed a significant SNP heritability of 20 % for Anhedonia (SE = 0.12; p < 0.046) and an estimate of 19 % for Cognitive Disorganization, which was close to significant (SE = 0.13; p < 0.059). Grandiosity and Paranoia showed modest SNP heritability estimates (17 %; SE = 0.13 and 14 %; SE = 0.13, respectively, both n.s.), and zero estimates were found for Hallucinations and Negative Symptoms. The estimates for Anhedonia, Cognitive Disorganization and Grandiosity accounted for approximately half the previously reported twin heritability. SNP heritability estimates from the MAF-stratified approach were mostly consistent with the standard estimates and offered additional information about the distribution of heritability across the MAF range of the SNPs. In contrast, the estimates derived from the pruned data were for the most part not consistent with the other two approaches. It is likely that the difference seen in the pruned estimates was driven by the loss of tagged causal variants, an issue fundamental to this approach. The current results suggest that common genetic variants play a role in the etiology of some adolescent psychotic experiences, however further research on larger samples is desired and the use of MAF-stratified approach recommended.

The Melbourne assessment of Schizotypy in kids: a useful measure of childhood schizotypal personality disorder

Despite being identified as a high risk cohort for psychosis, there has been relatively little research on the clinical presentation and assessment of Schizotypal Personality Disorder (SPD) in childhood. The current study aimed to develop a measure of childhood SPD (Melbourne Assessment of Schizotypy in Kids (MASK)) and assess discriminant validity against another neurodevelopmental disorder, autism spectrum disorder (ASD). Sixty-eight children aged between 5 and 12 (21 SPD, 15 ASD, and 32 typically developing) and their parents were administered the MASK. The MASK is a 57-item semistructured interview that obtains information from the child, their parents, and the clinician. The results showed high internal consistency for the MASK and higher scores in the SPD group. A factor analysis revealed two MASK factors: social/pragmatic symptoms and positive schizotypal symptoms. Both factors were associated with SPD, while only the social/pragmatic factor was associated with ASD. Within the two clinical groups, a receiver operating characteristic curve showed that the MASK (cut-off score: 132 out of 228) was a good indicator of SPD diagnosis. These preliminary MASK findings were reliable and consistent and suggest that childhood SPD is characterised by complex symptomology distinguishable from ASD.

Different combinations of perceptual, emotional, and cognitive factors predict three different types of delusional ideation during adolescence

Although adolescence is a particularly sensitive period for the development of schizotypy (Walker and Bollini [Schizophr Res 54:17-23, 2002]), there has been relatively limited research on the psychological factors that specifically predict delusional beliefs during adolescence. We studied 392 school students aged 11 to 16 years with a battery of behavioral and psychometric measures. Anxiety and negative-other schemas mediated the relationship between hallucinatory experiences and paranoid beliefs; anxiety mediated the relationship between hallucinatory experiences and grandiose beliefs; anxiety and self-negative schemas mediated the relationship between hallucinatory experiences and "other delusions" (Schneiderian/reference/misidentification). Furthermore, a jump-to-conclusions (JTC) bias moderated the relation between anxiety and other delusions: scores in the other delusions category were highest in adolescents who had both high anxiety and a JTC bias. Sex and age had only weak effects upon delusional belief. Our findings provide novel data by highlighting the different factors that underpin three delusional subtypes during the vulnerable period of adolescence.

Are genetic risk factors for psychosis also associated with dimension-specific psychotic experiences in adolescence?

Psychosis has been hypothesised to be a continuously distributed quantitative phenotype and disorders such as schizophrenia and bipolar disorder represent its extreme manifestations. Evidence suggests that common genetic variants play an important role in liability to both schizophrenia and bipolar disorder. Here we tested the hypothesis that these common variants would also influence psychotic experiences measured dimensionally in adolescents in the general population. Our aim was to test whether schizophrenia and bipolar disorder polygenic risk scores (PRS), as well as specific single nucleotide polymorphisms (SNPs) previously identified as risk variants for schizophrenia, were associated with adolescent dimension-specific psychotic experiences. Self-reported Paranoia, Hallucinations, Cognitive Disorganisation, Grandiosity, Anhedonia, and Parent-rated Negative Symptoms, as measured by the Specific Psychotic Experiences Questionnaire (SPEQ), were assessed in a community sample of 2,152 16-year-olds. Polygenic risk scores were calculated using estimates of the log of odds ratios from the Psychiatric Genomics Consortium GWAS stage-1 mega-analysis of schizophrenia and bipolar disorder. The polygenic risk analyses yielded no significant associations between schizophrenia and bipolar disorder PRS and the SPEQ measures. The analyses on the 28 individual SNPs previously associated with schizophrenia found that two SNPs in TCF4 returned a significant association with the SPEQ Paranoia dimension, rs17512836 (p-value = 2.57×10⁻⁴) and rs9960767 (p-value = 6.23×10⁻⁴). Replication in an independent sample of 16-year-olds (N = 3,427) assessed using the Psychotic-Like Symptoms Questionnaire (PLIKS-Q), a composite measure of multiple positive psychotic experiences, failed to yield significant results. Future research with PRS derived from larger samples, as well as larger adolescent validation samples, would improve the predictive power to test these hypotheses further. The challenges of relating adult clinical diagnostic constructs such as schizophrenia to adolescent psychotic experiences at a genetic level are discussed.

Emotion recognition and visual-scan paths in Fragile X syndrome

This study investigated emotion recognition abilities and visual scanning of emotional faces in 16 Fragile X syndrome (FXS) individuals compared to 16 chronological-age and 16 mental-age matched controls. The relationships between emotion recognition, visual scan-paths and symptoms of social anxiety, schizotypy and autism were also explored. Results indicated that, compared to both control groups, the FXS group displayed specific emotion recognition deficits for angry and neutral (but not happy or fearful) facial expressions. Despite these evident emotion recognition deficits, the visual scanning of emotional faces was found to be at developmentally appropriate levels in the FXS group. Significant relationships were also observed between visual scan-paths, emotion recognition performance and symptomology in the FXS group.

Why must we attribute our own action to ourselves? Auditory hallucination like-experiences as the results both from the explicit self-other attribution and implicit regulation in speech

The sense of agency, which is the awareness that "I am the one who causes action," is important in understanding passive schizophrenic symptoms and bodily self-consciousness. However, this potential linkage between subjective self-other attribution (explicit agency) and automatic self-monitoring of an action (implicit agency) has not been examined fully. The present study included two experiments conducted with the same group of healthy participants (N=48) in order to examine explicit (Exp. 1) and implicit (Exp. 2) measures of the sense of agency in speech. Exp. 1 suggested that participants who tend not to attribute a fed-back voice to themselves (the other-attribution group) might have a stronger tendency toward auditory hallucinations, as measured by the Auditory Hallucination Experience Scale 17 (AHES-17). Furthermore, the results of Exp. 2 suggested that this other-attribution group might not utilize auditory feedback during speech production, indicating the expected link between explicit and implicit agency. These results are discussed in relation to the sense-of-agency model, wherein people are understood to construct the online "self" monitoring of action.

Persisting psychotic-like experiences are associated with both externalising and internalising psychopathology in a longitudinal general population child cohort

BACKGROUND

Persisting psychotic-like experiences (PLEs) are associated with an increased risk of internalising symptoms in adolescence. Whether this association holds similarly for externalising symptoms, and from mid-childhood, is unclear. This prospective study investigated the extent to which PLE persistence was associated with internalising and externalising psychopathology in a community sample of children aged 9-11years at study commencement.

METHODS

8099 children (mean age 10.4years) completed questionnaires assessing PLEs, externalising and internalising symptoms. A subsample of 547 children completed reassessment, on average, two years later.

RESULTS

Two-thirds (66%) of children reported PLEs at baseline. Approximately two years later, PLEs persisted in 39% of those children. After adjustment for previous psychopathology and other potential confounds, children with persisting PLEs were at higher risk for internalising (odds ratio [OR]=1.94; 95% confidence interval [CI] 1.13-3.34) and externalising (OR=1.97; 95% CI 1.19-3.26) psychopathology than children whose PLEs remitted; and, than children who never presented PLEs.

CONCLUSIONS

Persistent PLEs from mid-childhood are associated with later internalising and externalising psychopathology in the general population, whereas transitory PLEs may be part of a spectrum of normative childhood development. Interventions that target persistent PLEs may contribute to a reduction in common childhood psychopathology.

Phenotypic expression of schizotypal traits in an adolescent population

The main goal of the present study was to examine the influence of gender and age in the phenotypic expression of schizotypal traits in a community sample of adolescents. The sample was composed of a total of 1,618 participants, 776 (48%) males, with a mean age of 15.9 years (SD = 1.2). The ESQUIZO-Q: Oviedo Schizotypy Assessment Questionnaire was used for the assessment of schizotypal traits, a measure specifically developed for its use in adolescents. The results showed that gender and age were two sociodemographical variables that influenced the expression of schizotypal features. The males in the study obtained higher mean scores than the females in the Negative dimension (Physical and Social Anhedonia); however, the females obtained higher mean scores in Magical Thinking, Lack of Close Friends, and Social Disorganization. With regard to age, the younger adolescents had lower scores in Odd Thinking and Language, Lack of Close Friends, Excessive Social Anxiety, and Social Disorganization compared to the older adolescents. This differential pattern is similar to the one found in patients with schizophrenia and in nonclinical young adults, and these findings improve our understanding about the phenotypic expression of schizotypy during adolescence.

Reliability and sources of validity evidence of the Oviedo Schizotypy Assessment Questionnaire-Abbreviated (ESQUIZO-Q-A)

The main goal of this research was to examine the reliability and different sources of validity evidence of the Oviedo Schizotypy Assessment Questionnaire-Abbreviated (ESQUIZO-Q-A) in nonclinical adolescents. The final sample was made up of 1,455 participants, 705 males (48.5%), with a mean age of 15.92 years (SD = 1.18). The internal consistency of the subscales ranged from .62 to .75. The analysis of its internal structure yielded a three-dimensional solution based on the dimensions: Reality Distortion, Anhedonia, and Interpersonal Disorganization. Likewise, the goodness-of-fit indices derived from the Confirmatory Factor Analysis for the hypothesized three-factor model were adequate. The three dimensions of the ESQUIZO-Q-A were significantly correlated with the subscales of the Strengths and Difficulties Questionnaire. The ESQUIZO-Q is a brief and simple self-report with adequate psychometric properties for the assessment of schizotypal traits in nonclinical adolescent populations. Future research should continue to explore the metric quality of the ESQUIZO-Q-A (e.g., sensitivity and specificity) and incorporate the new advances in psychological and educational assessment such as Computerized Adaptive Testing.

Symptoms associated with psychosis risk in an adolescent birth cohort: improving questionnaire utility with a multidimensional approach

AIM

Specialized self-report questionnaires have been developed for detection of symptoms indicative of psychosis risk. The identification of at-risk individuals is typically based on sum scores, which assume equal severity and discriminability of all symptoms, and a single dimension of illness. Our aim was to test whether separable dimensions of risk could be identified in the general population.

METHODS

We explored the latent structure of one such questionnaire using full-information item factor analysis, deriving exploratory models from the PROD-Screen questionnaire responses of the adolescent general population based on the Northern Finland 1986 Birth Cohort (n=6611).

RESULTS

A three-dimensional factor structure of positive, negative and general symptoms emerged. The factor structure, the appropriateness of the statistical model and the application of the results to the detection of heightened psychosis risk are discussed.

CONCLUSIONS

In explicitly taking into account the multidimensionality and varying symptom severity of the included items, the current model provides an improvement in questionnaire-based assessment of psychosis risk.

A psychometric approach to the relationship between hand-foot preference and auditory hallucinations in the general population: atypical cerebral lateralization may cause an abnormal sense of agency

The present study examined the relationship between the atypical cerebral lateralization pattern represented in hand and foot preferences and schizotypal personality traits, especially proneness to auditory hallucinations as related to a sense of agency. A sense of agency, measured with questionnaires in the present study, is the sense that "I am the one who causes the actions." Although atypical lateralization and an abnormal sense of agency may be related to schizophrenia or schizotypal personality, the connection between them has remained unclear. The present study used cluster analysis to categorize the handedness-footedness combinations. The results indicated that people with right-handedness and left-footedness may have more schizotypal traits and that their abnormal sense of agency may cause schizotypal personality traits. Although the reasons for crossed lateral preference remain unclear, we discuss this in terms of early switching in handedness, which may underlie atypical lateralization and lead to the experience of auditory hallucinations deriving from an abnormal sense of agency.

Going beyond students: an association between mixed-hand preference and schizotypy subscales in a general population

Research on the sub-clinical condition of schizotypy suggests that it is associated with mixed handedness. To date, however, this research has focussed on undergraduate populations. If the association between schizotypy and mixed-handedness is the result of an underlying neurological trait, it is important to demonstrate that the effect extends to the general population. With this in mind, 699 participants were drawn from a wide community sample. Schizotypy was measured using the Psychosis Proneness Questionnaire and handedness was assessed using the Annett inventory. To avoid the sometimes arbitrary definitions of left-, right- and mixed-handed, regression analyses were used to explore the data. There was no evidence of a difference in schizotypy between individuals with a left- or right-hand preference. People with a mixed-hand preference, however, had higher scores on PER-MAG (Perceptual Aberration and Magical Ideation) and HYP-IMP (Hypomania and Impulsive Non-Conformity) scales (positive traits). No effect was observed for the SAN (Social Anhedonia) and PAN (Physical Anhedonia) scales (negative traits). The nature of the association between schizotypy and handedness observed in the current study is similar to that reported for student populations. The possibility that the association is related to response biases or a biological mechanism is discussed.

Rubber hand illusion, empathy, and schizotypal experiences in terms of self-other representations

When participants observed a rubber hand being touched, their sense of touch was activated (rubber hand illusion: RHI). While this illusion might be caused by multi-modal integration, it may also be related to empathic function, which enables us to simulate the observed information. We examined individual differences in the RHI, including empathic and schizotypal personality traits, as previous research had suggested that schizophrenic patients would be more subject to the RHI. The results indicated that people who experience a stronger RHI might have stronger empathic and schizotypal personalites simultaneously. We discussed these relationships in terms of self-other representations.

The hierarchic structure in schizotypy and the five-factor model of personality

Schizotypal personality traits (schizotypy) might be seen as on a continuum with schizophrenia. However, controversy remains with regard to whether this continuum is quasi-dimensional, applying only to people with schizophrenia and schizotypy, or fully dimensional, applying to all people. If the fully dimensional model is accurate, schizotypy could be described by the same personality theories as are applied to people in general. We examined the relationship between schizotypy and the five-factor model of personality (FFM), which is arguably the most established contemporary personality theory. When we assumed a hierarchic structure of schizotypy factors, we found that the FFM scales could explain schizotypy fairly well regardless of the questionnaires used, suggesting that schizotypy might represent a variation better understood by reference to typical dimensions of personality, though it might still indicate a predisposition to schizophrenia. This article discusses this conclusion in relation to each of the five personality factors. A perspective that situates schizophrenia on a continuum with general personality variations implies that this disorder constitutes a potential risk for everyone and, thus, helps to promote understanding and correct misunderstandings that contribute to prejudice.

Psychometric properties of two measures for the assessment of Schizotypy in adolescents

The purpose of this study was to examine the psychometric properties of the Thinking and Perceptual Style Questionnaire (TPSQ) and the Multidimensional Schizotypal Traits Questionnaire-Reduced (MSTQ-R) in non-clinical adolescents. The final sample consisted of 991 participants with a mean age of 14.7 years (S.D.=1.8). The internal consistency of the TPSQ subscales ranged from 0.77 to 0.89, and that of the MSTQ-R subscales ranged from 0.62 to 0.81. Construct validity analysis from the TPSQ subscales showed a three-dimensional solution based on the factors social disorganisation, aberrant processing and anhedonia. For its part, factor analysis of the MSTQ-R also showed a three-dimensional solution based on the factors: positive symptoms, negative symptoms and impulsive-nonconformity. The TPSQ and MSTQ-R appear to have good psychometric properties and to be useful instruments for the measurement of schizotypy in adolescence. Moreover, the factor structure of these measures resembles that seen in young adult samples and provides further empirical evidence of the multidimensional structure of the instruments that we use to measure the complex schizotypy construct. Future research should explore in more depth the psychometric properties of these self-report instruments and improve our understanding of schizotypy in adolescents.

Effect of age and gender on schizotypal personality traits in the normal population

AIM

There is some evidence that age and gender influence expression of schizotypal traits in the normal population. One important limitation of previous studies, however, is the restricted age range of subjects. The aim of the present study was therefore to investigate the effect of gender and age on schizotypal personality features.

METHODS

A total of 1024 participants aged between 16 and 90 were assessed using the schizotypal personality questionnaire. The effect of gender and age on schizotypal features was investigated. Confirmatory factor analysis was used to examine the factor structure of the scale in different age groups.

RESULTS

Male subjects scored higher than women in negative and disorganized-like symptoms. Female subjects scored significantly in social anxiety and odd belief subscales. Younger participants significantly scored higher in reference, odd belief, unusual perceptual experiences, odd behavior and odd speech subscales. While decreases in schizotypy scores were gradual for most of the scales, increased disorganization in female subjects was restricted to late adolescence. Confirmatory factor analysis of the data supported modified versions of the Raine three-factor model across all age groups.

CONCLUSION

Psychological changes related to adolescence and better social adaptation as a result of life experience might contribute to the age- and gender-related differences in schizotypy.

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.

Schizotypal personality traits and atypical lateralization in motor and language functions

Atypical cerebral lateralization in motor and language functions in regard to schizotypal personality traits in healthy populations, as well as among schizophrenic patients, has attracted attention because these traits may represent a risk factor for schizophrenia. Although the relationship between handedness and schizotypal personality has been widely examined, few studies have adopted an experimental approach. This study consisted of three experiments focusing on motor and language functional lateralization in regard to schizotypal personality in the absence of mental illness: line-drawing, finger tapping, and a semantic go/no-go task. The results suggested that positive schizotypal personality might be related to functional non-lateralization in regard to at least some functions (e.g., spatial motor control and semantic processing in the present study). Subjects with high schizotypal personality traits performed equally with their right and left-hands in the line-drawing task and they reacted equally with their right and left-hands in a semantic go/no-go task involving semantic auditory stimuli presented in both ears. However, those low in schizotypal personality traits showed typical lateralization in response to these tasks. We discuss the implications of these findings for schizotypal atypical lateralization.

Hand-preference and population schizotypy: a meta-analysis

Language functions in schizophrenia patients are represented more bilateral, i.e. less lateralized than in healthy subjects. This decreased lateralization is also observed in individuals at increased risk for schizophrenia. Language lateralization is related to handedness; in that left- and mixed-handed individuals more frequently have decreased lateralization in comparison to right-handed subjects. Population schizotypy can be considered part of the schizophrenia spectrum disorders. In line with this, population schizotypy has repeatedly, though inconsistently, been associated with left-handedness. In order to define the exact association between handedness and schizotypy, we performed meta-analyses on the available literature. We found that non-right-handed subjects, but not strong left-handers, had higher scores on schizotypy questionnaires than right-handed subjects. Mixed-handers showed a trend towards higher schizotypy in comparison to strong left-handers. It is argued that the higher schizotypy in non-right-handed individuals reflects the higher incidence of bilateral language lateralization in this group. Bilateral language organisation may underlie loosening of association, possibly leading to higher schizotypy scores.

Schizotypy in adolescence: the role of gender and age

Schizotypy is a multidimensional personality construct that appears to indicate psychosis proneness. Supposedly, schizotypal traits behave differently depending on a person's age and gender, but few studies have examined this relationship. In our study we used the Thinking and Perceptual Style Questionnaire and the Junior Schizotypy Scales. The sample was made up of 321 students (169 males) with an age range of 12 to 17 years. The results show significant differences in gender and age groups. Males score higher than females on Physical Anhedonia, Social Anhedonia, and Impulsive Non-Conformity scales, while females score higher or Positive Symptoms, Negative Evaluation, and Social Paranoia scales. Significant differences were also found among age groups: Unusual experiences, self-referent ideation, social paranoia, thought disorder, and negative evaluation were more frequent in later stages of adolescence. However, the meaning of this difference could be interpreted in terms of emotional turbulence rather than as a direct indicator of vulnerability to psychosis.

Highly schizotypal students have a weaker sense of self-agency

Schizotypy can be seen as an indicator of a predisposition to schizophrenia. It is possible that schizotypal people have an abnormal self-consciousness, especially with regard to the sense of self-agency. Students were rated using the Schizotypy Traits Questionnaire (STA). They were asked to press a button, which generated a tone after some delay. They were then required to judge whether they felt they or someone else had generated the tone. The results showed that the high schizotypy group had a weaker sense of self-agency than the low schizotypy group. The present study used an experimental method to show that schizotypal traits are correlated with an abnormal sense of self-agency.

The relationship between the sense of self-agency and schizotypal personality traits

People with schizotypal traits may possess abnormal self-awareness, particularly with regard to their sense of self-agency, that is, the sense that it is oneself who is causing or generating an action. Participants in Experiments 1A (N = 11), 1B (N = 12), and 2 (N = 20) moved a mouse device and viewed resultant feedback, which was biased either temporally or spatially. They then judged whether there was a bias or whether they felt they had moved the cursor on their own. The authors found, for the 1st time, that a sense of self-agency can be experienced even if some degree of temporal bias is perceived. Furthermore, they determined that highly schizotypal people have an abnormal (weaker) sense of self-agency.