Factor versus cluster models of schizotypal traits. II: relation to neuropsychological impairment.

Heterogeneity in cognitive performance in schizophrenia and schizotypy may be accounted for, by differences in predominant symptom presentation. However, studies have not demonstrated consistent relations between specific cognitive impairments and specific trait dimensions in either population. Studies of group differences, particularly those using groups defined by cluster analyses are rare, but suggest that the negative trait dimension is more associated with executive function deficits, positive trait dimension with memory and attentional difficulties, and the disorganized trait dimension with attention problems. The present study examined the relation of schizotypal trait dimensions and executive function deficits in schizotypal individuals using two methods. Correlations between schizotypal factor scores and cognitive measures demonstrated that high negative symptoms were associated with poor performance on the WCST, while high scores on other trait dimensions were related to a better WCST performance. High scores in all trait dimensions were related to the na?ve rater's observations of unusual social behavior. A cluster analysis revealed three groups of schizotypals (predominantly negative presentation, predominantly positive symptom presentation, and high on all dimensions). The cluster with predominantly negative symptoms performed worse, than all other schizotypal groups and unselected controls, on the WCST and a higher percentage of them were rated as clinically impaired on the neuropsychological battery. However, schizotypals who were high on all trait dimensions were rated as having the most unusual social behavior by the na?ve raters. Overall, results support the hypothesis of a relation between executive function deficits and negative symptoms in schizotypal individuals.     

An obsessive-compulsive subtype of schizotypy: evidence from a nonclinical sample

Obsessive-compulsive (OC) and schizotypal symptoms are highly correlated in clinical samples. The current study investigated the presence of schizotypal and OC symptomatology in a large undergraduate sample using factor and cluster analysis and t test comparison of cluster groups. Separate clusters of individuals reporting high levels of schizotypal and OC symptoms versus purely schizotypal symptoms emerged and demonstrated different overall symptom profiles. Individuals with high levels of pure schizotypy symptoms demonstrated a prevalence of interpersonal symptoms, including restricted affect, and few close friends. In contrast, those with high levels of both schizotypy and OC symptoms demonstrated higher cognitive/perceptual symptoms, including ideas of reference and suspiciousness. Consistent with research in clinical populations, results suggest greater prevalence of positive symptoms in individuals experiencing both schizotypal and OC disorder symptoms.     

Handedness and schizotypal features in healthy subjects.

BACKGROUND: An excess of mixed-handedness has been repeatedly reported in schizophrenia and schizotypy. Handedness is a measure of atypical cerebral lateralization, which is considered as a risk factor for schizophrenia. Several studies have attempted to identify correlations between handedness and dimensions of psychosis but the results obtained so far remain inconclusive. OBJECTIVE: To explore a possible link between mixed-handedness and the three classical dimensions of psychosis. As speech and language disorders may be associated with cerebral lateralization, we predicted a correlation between mixed-handedness and disorganized dimension. METHODS: We used the Schizotypal Personality Questionnaire (SPQ) and the Edinburgh Handedness Inventory (EHI) to study the correlation between mixed-handedness scores and positive, negative or disorganized dimensions in a sample of 62 healthy subjects. RESULTS: We found a negative correlation between mixed-handedness and the disorganized dimension of schizotypy, as individuals with prominent mixed-handedness showed more severe disorganization. CONCLUSION: We have identified a link between mixed-handedness and the disorganized dimension that may help to identify genetic vulnerability factors involved in psychosis.     

Interactive decision-making in people with schizotypal traits: A game theory approach

Studies that have investigated whether deficits in social cognition observed in schizophrenia are also present in schizotypal individuals have largely been inconclusive, and none of these studies have examined social interactive behavior. Here, we investigated interactive decision-making behavior in individuals differing in the amount of schizotypal symptoms using tasks derived from Game Theory. In total 1691 undergraduate students were screened with the Schizotypal Personality Questionnaire-Brief version. We selected 69 people distributed across the full schizotypal continuum to participate in Ultimatum and Dictator Games in which they played against human and non-human, computer partners. The results showed that higher levels of schizotypal symptoms, particularly positive and disorganized schizotypy, were related to proposing higher offers to all partners. Additionally, the amount of interpersonal schizotypal symptoms was associated with an increased acceptance rate of very unfair offers from human partners, possibly reflecting a blunted emotional response to such offers. We conclude that positive and disorganized schizotypal symptoms are associated with less adequate bargaining behavior, similar to what has been recently observed in patients with schizophrenia. The observed similarities on Ultimatum Game behavior between patients with schizophrenia and individuals with more schizotypal symptoms contribute to the growing evidence that social cognitive deficits may represent a marker of vulnerability to schizophrenia.     

Cognitive profiles of schizotypal dimensions in a community cohort: Common properties of differential manifestations

Introduction: Studies assessing the effects of schizotypal dimensions (i.e., positive, negative, and disorganized) on cognitive functions have yielded mixed findings. In the present study, we administered an extensive battery of cognitive tasks to a community sample and defined the schizotypal dimensions according to a more analytical four-factor model, whereby positive schizotypy is further divided into cognitive–perceptual and paranoid. Method: Two hundred healthy community participants were assessed for schizotypy with the Schizotypal Personality Questionnaire; assessment of cognitive functions included set shifting, working memory, processing speed, verbal fluency, attention switching, planning/problem solving, strategy formation, and abstract reasoning. Associations between cognitive tasks and schizotypy were examined with hierarchical multiple linear regressions. We also divided our subjects into groups based on whether or not their scores in the negative, positive, and cognitive–perceptual factors fell in the upper 10% of the scores of a large community normative sample in Greece and examined between-group differences. Results: Applying both dimensional and categorical approaches, we showed that (a) attention-switching impairment is a “core” deficit of both negative and paranoid schizotypy, (b) impaired working memory and set shifting are associated mainly with negative and to a lesser extent paranoid schizotypy, (c) paranoid schizotypy is associated with reduced performance in tasks requiring intact frontotemporal connectivity, and (d) cognitive–perceptual and disorganized schizotypy are not associated with any cognitive functions. Conclusions: Our findings further support the more analytical four-factor categorization of schizotypy and suggest that the discrepancies in the findings so far might be due to a more “generalized” definition of the schizotypal dimensions. They also add further in the early formulation of the profile of the high-schizotypal individuals seeking psychiatric help so that their overall management is directed towards a more targeted approach.     

Higher prefrontal cortical thickness in high schizotypal personality trait

A model of schizophrenia-spectrum disorders hypothesized that schizotypy shares biomarkers with schizophrenia but due to protective factors such as a greater prefrontal cortex those individuals have a reduced vulnerability to schizophrenia. In contrast to previous studies exploring volumetric brain correlates of schizotypy focussing on clinical samples or relying on between-group comparisons we measured cortical thickness and correlated it with the expression of schizotypal personality traits in a mentally healthy sample. We acquired high-resolution MRI scans from 34 subjects and used FreeSurfer to model the grey-white and pial surfaces for each individual cortex in order to compute the distance between these surfaces to obtain a measure of cortical thickness. Differences in cortical thickness were correlated with positive and negative factors of schizotypy as assessed by means of the schizotypal personality questionnaire. We found a significant positive correlation between right dorso-lateral prefrontal cortex (DLPFC) and right dorsal premotor cortex/frontal eye fields (dPMC/FEF) and the total schizotypy score, between right DLPFC and the positive factor, and between right temporo-parietal junction and the negative factor of schizotypy. The volume of thalamus was negatively correlated with schizotypy. A significant negative correlation between thalamus volume and dPMC/FEF cortical thickness was observed. One may speculate that this finding is in line with the hypothesis of a compensatory role of greater prefrontal cortex in schizotypy in healthy populations.     

Quality of life across the schizotypy spectrum: findings from a large nonclinical adult sample

Objective

It is well documented that patients with schizophrenia have impoverished quality of life (QOL). Efforts to determine the underpinnings of this impoverishment have implicated negative symptoms more than positive or disorganized symptoms. However, only a minority of individuals with the liability to schizophrenia will ever show manifest illness, and it is presently unclear the degree to which QOL is affected in individuals with subclinical symptoms of the disorder (ie, schizotypy). The present study examined the relative contributions of negative, positive, and disorganized schizotypy symptoms to QOL.

Methods

Measures of schizotypal symptoms and subjective and objective QOL were obtained from a sample of 1395 adults.

Results

Measures of schizotypal symptoms significantly corresponded to all measures of QOL, although the magnitude of correlations were significantly larger for subjective than objective measures. The negative symptom dimension explained a substantial portion of unique variance in the social domains of QOL above and beyond that accounted for by the other schizotypy dimensions.

Conclusions

These findings highlight the deleterious impact of schizotypal symptoms, particularly negative symptoms. Further research clarifying the mechanism underlying this relationship is called for.     

Cannabis and psychometrically-defined schizotypy: Use, problems and treatment considerations

Cannabis use is associated with onset of psychosis in individuals vulnerable for developing schizophrenia-spectrum disorders. The present study addressed three knowledge gaps pertaining to this issue: 1) clarifying the incidence of cannabis use in schizotypal individuals, 2) examining how cannabis use is related to psychosocial and physiological problems in schizotypy and interest in treatment, and 3) examining how cannabis use is associated with positive, negative and disorganization features of schizotypy. Scores from a measure of schizotypal traits were used to trichotomize 1665 young adults into schizotypy (top 5% of scorers), non-schizotypy (bottom 50% of scorers) and “unconventional” (scorers within the 50th to 85th percentile) groups. Nearly a quarter of the schizotypy group endorsed cannabis use at least weekly, a rate nearly two to four times that of the other groups. The schizotypy group also reported a much greater frequency of cannabis-related problems compared to the other groups. Despite this, interest in treatment for cannabis use in the schizotypy group was not elevated. Interestingly, 85% of individuals in the schizotypy group reported interest in psychological/psychiatric treatment more generally. Cannabis use was not associated with abnormal patterns of positive or disorganized schizotypy traits in the schizotypy group relative to the other groups. However, cannabis use was associated with lower severity of negative traits. Implications of these results are discussed.     

Overlap of autistic and schizotypal traits in adolescents with Autism Spectrum Disorders

This study addresses the unraveling of the relationship between autism spectrum and schizophrenia spectrum traits in a population of adolescents with Autism Spectrum Disorders (ASD). Recent studies comparing isolated symptoms of both spectrum disorders as well as diagnostic criteria for each (DSM-IV-TR) suggest resemblances in the clinical phenotype. A group of 27 adolescents with ASD (11 to 18 years) and 30 typically developing adolescents, matched for age and gender, participated in this study. Within the ASD group 11 adolescents satisfied DSM-IV-TR criteria for schizotypal personality disorders. Autistic and schizotypal traits were identified by means of well validated questionnaires (Autism Questionnaire, AQ and Schizotypal Personality Questionnaire-Revised, SPQ). Significantly more schizotypal traits in adolescents with ASD were found than in typically developing controls. Besides high levels of negative symptoms, adolescents with ASD also displayed high levels of positive and disorganized symptoms. There appeared to be a relationship between the mean level of autistic symptoms and schizotypal traits, as well as specific associations between autistic symptoms and negative, disorganized and positive schizotypal symptoms within individuals. Schizotypal symptomatology in all sub dimensions that are reflected by the SPQ scores, was most prominently associated with attention switching problems of the autism symptoms from the AQ. These findings indicate that patients diagnosed with an ASD show schizophrenia spectrum traits in adolescence. Although other studies have provided empirical support for this overlap in diagnostic criteria between both spectrum disorders, the present findings add to the literature that behavioral overlap is not limited to negative schizotypal symptoms, but extends to disorganized and positive symptoms as well.     

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 significantlyscored 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.     

Negative schizotypal traits predict the reduction of reward motivation in effort–reward imbalance

The schizotypy construct is useful for studying the effects of environmental stress on development of subclinical negative symptoms. The relationship among self-report motivation, effort–reward imbalance (ERI), and schizotypal features has seldom been studied. We aimed to examine the possible moderation effect of schizotypal traits on ERI and reward motivation. Eight-hundred-and-forty-three college students were recruited online to complete a set of self-reported measures capturing schizotypal traits, effort–reward imbalance and reward motivation, namely the Schizotypal Personality Questionnaire (SPQ), the Effort–Reward Imbalance-School Version Questionnaire (C-ERI-S) and the Motivation and Pleasure Scale-Self Report (MAP-SR). We conducted multiple linear regression to construct models to investigate the moderating effects of schizotypal traits on the relationship between ERI and reward motivation. Stressful ERI situation predicted the reduction of reward motivation. Negative schizotypal traits showed a significant negative moderating effect on the relationship between ERI and reward motivation, while positive and disorganized schizotypal traits had significant positive moderating effects. Schizotypal traits subtypes differently moderate the relationship between ERI and reward motivation. Only negative schizotypal traits and stressful ERI situation together have negative impact on reward motivation.

     

Relationship between positive and negative symptoms of schizophrenia and schizotypal symptoms in nonpsychotic relatives.

BACKGROUND: Continuous rather than categorical measures of psychopathology may provide greater statistical power to detect susceptibility loci for schizophrenia. However, it has not been established that the dimensions of schizophrenic symptomatology and personality traits in nonpsychotic individuals share etiological factors. We therefore sought to clarify the relationship between positive and negative symptoms of schizophrenic probands and dimensions of schizotypy in their first-degree relatives. METHODS: In the Roscommon Family Study, we examined the ability of positive and negative symptoms in probands to predict 7 factors of schizotypy in nonpsychotic relatives using regression analysis. These consisted of positive, negative, and avoidant symptoms; odd speech; suspicious behavior; social dysfunction; and symptoms of borderline personality disorder. We examined 3 proband groups: schizophrenia (n = 127); schizophrenia, simple schizophrenia, and schizoaffective disorder (n = 178); and all nonaffective psychoses (n = 216), and their nonpsychotic relatives (n = 309, 477, and 584, respectively). RESULTS: Positive symptoms in all nonaffective psychoses probands predicted positive schizotypy (beta = 0.1972, P =.0004), social dysfunction (beta = 0.0719, P =.0489), and borderline personality disorder symptoms (beta = 0.1327, P =.0084) in relatives, while negative symptoms predicted negative schizotypy (beta = 0.2069, P =.0002), odd speech (beta = 0.2592, P =.0001), suspicious behavior (beta = 0.2749, P =.0001), and social dysfunction (beta =.2398, P =.0002). Proband negative symptoms and borderline personality disorder symptoms in relatives in the schizophrenia, simple schizophrenia, and schizoaffective disorder group were inversely related (beta = -0.1185, P =.05). CONCLUSIONS: Positive and negative symptoms in schizophrenia predict corresponding schizotypal symptoms in relatives. This provides evidence that these schizophrenic symptom factors (1) are etiologically distinct from each other and (2) occur on an etiological continuum with their personality-based counterparts.     

Associations between schizotypal personality traits and the facilitation and inhibition of the speed of contextually cued responses

This study measured schizotypal personality traits in a sample of 33 healthy participants using the Oxford-Liverpool Inventory of Feelings and Experiences. These traits were correlated with measures of inhibition and facilitation of response times (RTs) within a cued letter-comparison task. It was expected that scores on a measure of positive schizotypy, reflecting unrealistically distorted perceptions and beliefs, would be negatively associated with inhibition of RTs to targets that were unexpected in the context of the preceding letter cue. No specific predictions were made for the facilitation of RTs to targets expected in the context of the cues. The predicted negative association for positive schizotypy and inhibition of RTs was confirmed. There was no significant association between positive schizotypy and facilitation of RTs; however, there was an unpredicted finding that facilitation of RTs was increased in individuals with higher levels of disorganized schizotypy. The findings for positive schizotypy were consistent with Hemsley's model, in that high positive schizotypy results from a weakening of contextually elicited inhibitory processes, and is associated with altered functioning of a monitoring system. The normal functioning of the monitoring system is to generate mismatch signals that interrupt information processing when a contextually unexpected stimulus occurs.     

Association between cannabis use and schizotypal dimensions – A meta-analysis of cross-sectional studies

Cannabis consumption can cause abuse and dependence and increase risk of developing psychiatric and somatic disorders. Several literature reviews explored the link between cannabis consumption and schizophrenia but none summarized the rich literature on cannabis and psychometric schizotypy. The aim of our review is to synthesize data from studies that explored the association between cannabis consumption and schizoptypal dimensions. A systematic review of the literature and, when needed, contact with the authors, allowed us to gather data from 29 cross-sectional studies. We compared schizotypy scores between subjects that never used cannabis and subjects that used it at least once (“never vs. ever”) and between current users and subjects that do not use cannabis currently (“current vs. other”). We conducted separate analyses for total schizotypy score and each of the three classical schizotypal dimensions (positive, negative, disorganized). For all eight comparisons, the cannabis group (“ever” or “current”) had higher schizotypy scores. Differences were in the small or medium range and, with the exception of the negative score in the current vs. other comparison, statistically significant. Cannabis consumption is associated with increased schizotypal traits. More research, using different approaches (e.g. longitudinal studies) is needed to explore the cause of this association.     

Communication disturbances, working memory, and emotion in people with elevated disorganized schizotypy

This study examined whether people with elevated disorganized schizotypy would differ from control participants on characteristics associated with disorganization symptoms in schizophrenia and also whether disorganized schizotypy was associated with problems processing emotion. People with disorganized schizotypy (n = 32) exhibited greater communication disturbances (CD) than control participants (n = 34) for emotionally negative topics but not for positive topics. In addition, the disorganized group exhibited poorer performance on a working memory task but not on a psychometrically matched verbal intelligence task. In addition, poor working memory was associated with increased CD for negative topics and, after controlling for group differences in working memory, group differences in CD were not significant. Moreover, the disorganized group exhibited greater emotional ambivalence and ambivalence was associated with increased CD in the disorganized group. These results suggest that people with disorganized schizotypy exhibit some similar characteristics to people with schizophrenia who have disorganization symptoms and that disorganized schizotypy is also associated with poor emotion processing.     

A prospective longitudinal 10-year study of schizophrenia's three major factors and depression

This study investigated the nature, independence, and stability of schizophrenia's syndrome factors and depression at 2, 4.5, 7.5 and 10 years post-index hospitalization. At the four follow-ups, 71 patients (48 with schizophrenia and 23 with schizoaffective disorder) were assessed for symptoms hypothesized to constitute the reality distortion, disorganized, and negative factors of schizophrenia. At the last three follow-ups, the patients were also assessed for symptoms of depression. Factor analyses of schizophrenia symptoms revealed more than three syndrome factors at each follow-up. Longitudinally, reality distortion was a stable and relatively independent factor. The negative syndrome was independent but was bifurcated into two dimensions, interpreted as social/emotional withdrawal and diminished movement/expressiveness. Although signs of disorganization were not unified or independent early in schizophrenia's course, speech/thought disorder, disorganized affect, and poverty of speech content coalesced to form a disorganization factor by the 7.5-year follow-up. When depressive symptoms were added to the analyses, depression constituted an independent and stable dimension of schizophrenia over time. Each schizophrenia factor demonstrated a unique longitudinal course. Courses included stable symptom consistency (reality distortion), evolving symptom convergence (disorganization), and recurrent bifurcation and symptom instability (the negative syndrome).     

Facial affect recognition and schizotypal personality characteristics

Aim: Deficits in facial affect recognition are well established in schizophrenia, yet relatively little research has examined facial affect recognition in hypothetically psychosis‐prone or ‘schizotypal’ individuals. Those studies that have examined social cognition in psychosis‐prone individuals have paid little attention to the association between facial emotion recognition and particular schizotypal personality features. The present study therefore sought to investigate relationships between facial emotion recognition and the different aspects of schizotypy. Methods: Facial affect recognition accuracy was examined in 50 psychiatrically healthy individuals assessed for level of schizotypy using the Schizotypal Personality Questionnaire. This instrument provides a multidimensional measure of schizophrenia proneness, encompassing ‘cognitive‐perceptual’, ‘interpersonal’ and ‘disorganized’ features of schizotypy. It was hypothesized that the cognitive‐perceptual and interpersonal aspects of schizotypy would be associated with difficulties identifying facial expressions of emotion during a forced‐choice recognition task using a standardized series of colour photographs. Results: As predicted, interpersonal aspects of schizotypy (particularly social anxiety) were associated with reduced accuracy on the facial affect recognition task, but there was no association between affect recognition accuracy and cognitive‐perceptual features of schizotypy. Conclusions: These results suggest that subtle deficits in facial affect recognition in otherwise psychiatrically healthy individuals may be related to the vulnerability for interpersonal communication difficulties, as seen in schizophrenia.     

A quantitative association study between schizotypal traits and COMT, PRODH and BDNF genes in a healthy Chinese population

Previous studies have suggested that catechol-O-methyltransferase (COMT), proline dehydrogenase (PRODH), and brain-derived neurotrophic factor (BDNF) genes are possible susceptibility genes for schizophrenia. We hypothesized that these genes are also associated with schizotypal traits, which are heritable and related to schizophrenia. We genotyped five single nucleotide polymorphism (SNPs) from the COMT, PRODH and BDNF genes, and performed a series of association analyses between alleles, genotypes or haplotypes, and quantitative schizotypal trait scores derived from the Schizotypal Personality Questionnaire (SPQ), in 465 Chinese healthy subjects. We found that 'years of education' was a major influence on seven out of nine schizotypal components, three schizotypal factors and the total SPQ scores. Molecular genetic analysis of COMT, PRODH and BDNF genes showed no significant effects of any variants on schizotypal components or factors of SPQ after correction for multiple testing, although there were weak association between COMT Val158Met (rs4680G/A) and the odd speech subscale (allele-wise, P=0.04; genotype-wise, P=0.049), between COMT Val158Met (rs4680G/A) and the suspiciousness subscale (genotype-wise, P=0.024), and between BDNF Val66Met and the Factor 2 interpersonal measure (genotype-wise, P=0.027) before correction. Furthermore, we found SNP Val158Met (rs4680) of the COMT gene significantly influenced the scores of some of schizotypal traits including total SPQ score, the disorganization factor and the constricted affect subscale in male subjects only. However, the effect was in the opposite direction of an earlier association with the SPQ reported by Avramopoulos et al. [Avramopoulos, D., Stefanis, N.C., Hantoumi, I., Smyrnis, N., Evdokimidis, I., Stefanis, C.N., 2002. Higher scores of self reported schizotypy in healthy young males carrying the COMT high activity allele. Molecular Psychiatry 7, 706-711]. We conclude that SNP Val158Met (rs4680) in the COMT gene may be associated with some schizotypal traits in male subjects, but our results are not conclusive.     

Elevated levels of schizotypal features in parents of patients with a family history of schizophrenia spectrum disorders

There is some evidence that schizotypal traits are related to a genetic or familial liability to develop schizophrenia. However, it is unclear whether the number of schizotypal traits is elevated in parents of schizophrenia patients compared with controls. This study used the Schizotypal Personality Questionnaire to investigate the difference in number of schizotypal traits between both parents of 36 patients with schizophrenia (n = 72 persons) and 26 healthy married control couples (n = 52 persons). Parents of patients had a lower score on the positive dimension of schizotypy than healthy controls. There was no difference on the negative or disorganization dimension between groups. The difference on the positive dimension might have been caused by a difference in response style between parents of patients and controls due to the fact that parents are more familiar with schizophrenia than controls. Of interest, parents with a family history of schizophrenia spectrum disorders had more positive and negative schizotypal traits than parents without a family history of schizophrenia spectrum disorders. Because these two groups of parents differ in only genetic risk, not familiarity with schizophrenia, results suggest that the negative and positive dimension of schizotypy are related to a familial or genetic vulnerability to schizophrenia.