Neuropsychological dysfunction in schizotypal personality disorder: a profile analysis

Atypical semantic cognition in schizotypal personality disorder and borderline personality disorder

Increased schizotypal traits have previously been associated with atypical semantic cognition in community samples. However, no study has yet examined whether adults diagnosed with schizotypal personality disorder (SPD) display atypical semantic fluency and memory. We hypothesized that 24 adults diagnosed with SPD would name more idiosyncratic words on the semantic fluency task and show decreased semantic recall for animal and fruit category words compared with 29 participants with borderline personality disorder (BPD) and a community sample of 96 age-matched controls. We examined whether atypical semantic cognition was specifically associated with disorganized and eccentric speech and thinking, or more broadly with pathological personality traits and personality functioning. Our main hypothesis was confirmed, as the SPD participants named more idiosyncratic words and recalled fewer semantically related words compared with controls. Surprisingly, participants with BPD likewise named more atypical words compared with controls. More idiosyncratic semantic fluency was associated with more eccentric speech and thinking. Increased idiosyncratic semantic fluency and reduced semantic recall were both coupled to increased detachment and lowered personality functioning, while reduced semantic recall further was related to increased interpersonal problems. Our findings suggest that persons with SPD, and to a lesser degree BPD, show atypical semantic cognition, which is associated with eccentric speech and thinking, and more broadly with impaired personality function, social withdrawal, and emotional flatness. The idiosyncratic semantic cognition may worsen difficulties with social reciprocity seen in SPD and BPD.

Semantic clustering on common list-learning tasks: a systematic review of the state of the literature and recommendations for future directions

INTRODUCTION

On some list-learning tasks, such as the California Verbal Learning Test (CVLT) or Hopkins Verbal Learning Test (HVLT), examinees have the opportunity to group words based on semantically related categories (i.e., semantic clustering). Semantic clustering (SC) is often considered the most efficient organizational strategy and adopting SC is presumed to improve learning and memory. In addition, SC is conceptualized as reflecting higher-order executive functioning skills. Although SC measures have intuitive appeal, to date, there are no comprehensive reviews of the SC literature base that summarize its psychometric utility. In this systematic review, we synthesize the literature to judge the validity of SC scores.

METHOD

We conducted a systematic literature search for empirical articles reporting SC from the CVLT and HVLT. We qualitatively described the relationship of SC with other list-learning and cognitive test scores and clinical diagnoses, contrasting SC with serial clustering and total learning scores when possible.

RESULTS

SC was inversely correlated with serial clustering. Higher SC was strongly associated with better learning and memory performances. When compared with cognitive tests, SC tended to have the strongest relationships with other memory measures and modest relationships with tests of executive functioning. SC had negligible to small relationships with most other cognitive domains. Traditional memory scores yielded stronger relationships to cognitive test performances than did SC. SC across clinical groups varied widely, but clinical groups tended to use SC less often than healthy comparison groups.

CONCLUSION

Our comprehensive review of the literature revealed that SC is strongly related to measures of learning and memory on the CVLT and HVLT and is correlated with a wide range of cognitive functions. SC has been understudied in relevant populations and additional research is needed to test the degree to which it adds incremental validity beyond traditional measures of learning and memory.

Amphetamine-induced striatal dopamine release in schizotypal personality disorder

RATIONALE

Previous research has suggested that schizotypal personality disorder (SPD), a condition that shares clinical and cognitive features with schizophrenia, may be associated with elevated striatal dopamine functioning; however, there are no published studies of dopamine release within subregions of the striatum in SPD.

OBJECTIVES

To characterize dopamine release capacity in striatal subregions and its relation to clinical and cognitive features in SPD.

METHODS

We used positron emission tomography with [¹¹C]raclopride and an amphetamine challenge to measure dopamine D2-receptor availability (binding potential, BP_ND), and its percent change post-amphetamine (∆BP_ND) to index amphetamine-induced dopamine release, in subregions of the striatum in 16 SPD and 16 healthy control participants. SPD participants were evaluated with measures of schizotypal symptom severity and working memory.

RESULTS

There were no significant group differences in BP_ND or ∆BP_ND in any striatal subregion or whole striatum. Among SPD participants, cognitive-perceptual symptoms were associated at trend level with ∆BP_ND in the ventral striatum, and disorganized symptoms were significantly negatively related to ∆BP_ND in several striatal subregions.

CONCLUSIONS

In contrast to previous findings, SPD was not associated with elevated striatal dopamine release. However, in SPD, there was a moderate positive association between ventral striatal dopamine release and severity of cognitive-perceptual symptoms, and negative associations between striatal dopamine release and severity of disorganized symptoms. Future larger scale investigations that allow for the separate examination of subgroups of participants based on clinical presentation will be valuable in further elucidating striatal DA functioning in SPD.

Schizotypal traits and cognitive performance in siblings of patients with psychosis

INTRODUCTION

Schizotypy has been proposed to be the expression of genetic vulnerability to schizophrenia. The available literature shows cognitive similarities between schizotypy and schizophrenia, with mildly impaired performance being associated with schizotypy. This study aims to determine the relationship between schizotypy and cognitive performance in siblings of patients with psychosis.

METHODS

Schizotypal features and cognitive performance on a neuropsychological battery were compared between 48 siblings of patients with psychosis and 44 healthy controls. The relationships between schizotypy and cognitive performance were analysed by controlling the condition of being a sibling.

RESULTS

Siblings showed poorer performance on vigilance/sustained attention (M = 37.6; SD = 7.1) and selective attention/interference control/working memory (M = 23.28; SD = 2.7) tasks. The variance in vigilance/sustained attention performance was explained, at 30%, by the interpersonal factor of schizotypy on the suspiciousness dimension and the condition of being a sibling.

CONCLUSIONS

Interpersonal features of schizotypy in siblings of patients with psychosis are associated with deficits in vigilance/sustained attention performance.

Neuropsychological Profile in Patients with Schizotypal Personality Disorder or Schizophrenia

Neuropsychological impairments have been consistently reported in patients with schizophrenia. As little is known whether subjects with schizotypal personality disorder exhibit neurocognitive dysfunction similar to that in schizophrenia, we assessed the neuropsychological profile of 15 subjects with schizotypal personality disorder and compared it with that for 15 patients with schizophrenia and for 15 psychiatrically normal volunteers. All participants were administered a standard neuropsychological battery assessing language ability, spatial ability, visuomotor function, verbal memory, visual memory, auditory attention, visual attention, and executive function. Performance on most of the cognitive domains was impaired in patients with schizotypal personality disorder but less than patients with schizophrenia. Specifically, impairment in verbal memory and visuomotor ability in patients with schizotypal personality disorder and patients with schizophrenia were comparable, while patients with schizophrenia performed worse on the test of executive function than did patients with schizotypal personality disorder. As a whole, cognitive deficits in patients with schizotypal personality disorder were qualitatively similar to, but quantitatively milder than, those for patients with schizophrenia. The results suggest that cognitive abilities related to frontotemporal lobe function are disturbed across these schizophrenia-spectrum disorders.

Structural alterations of the pyramidal pathway in schizoid and schizotypal cluster A personality disorders

AIM

Schizoid (ScPD) and Schizotypal (SPD) personality disorders are rare and severe disorders. They are associated with high liability to schizophrenia and present an attenuated form of its negative symptoms, which are considered a putative endophenotype for schizophrenia. The trans-diagnostic study of negative symptoms in non-psychotic populations such as ScPD/SPD might provide useful markers of a negative-symptom domain; however, little is known about their neurobiological substrates. The aim of the study was to investigate differences in gray and white matter volumes in subjects with ScPD/SPD compared to a group of healthy controls.

METHODS

Structural magnetic resonance images were obtained from 20 never-psychotic subjects with ScPD/SPD and 28 healthy controls. Resulting values from clusters of differences were correlated in patients with relevant clinical variables (O-LIFE scale).

RESULTS

ScPD/SPD presented greater bilateral white matter volume compared to healthy controls in the superior part of the corona radiata, close to motor/premotor regions, which correlated with the O-LIFE subtest of cognitive disorganization. No differences were found in regional gray matter or global gray/white matter volumes.

CONCLUSION

Greater volumes in motor pathways might relate to cognitive symptoms and motor alterations commonly present in schizophrenia-related disorders. Given the established link between motor signs and psychosis, structural alterations in motor pathways are suggested as a putative biomarker of a negative-symptom domain in psychosis subject to further testing.

Neurological soft signs in Chinese adolescents with schizophrenia and schizotypal personality traits

OBJECTIVE

Neurological soft signs (NSSs) may reflect neurodevelopmental anomalies in association with the spectrum of schizophrenia disorders. We examined NSSs in Chinese adolescents with schizophrenia and schizotypal personality traits.

METHODS

Eighty-seven schizophrenic adolescents (SCH group), 85 adolescents with only schizotypal personality traits (SPT group), and 88 healthy controls (HC group) were enrolled. The NSS subscales of the Cambridge Neurological Inventory (CNI) were administered to all 260 participants.

RESULTS

The NSS prevalence rates were higher in the SCH group than in the other two groups for both hands in the fist-edge-palm, Oseretsky, and graphesthesia tests. Relative to HCs, the SCH group also showed higher NSS prevalence rates in the right finger agnosia and right mirror movement of finger opposition tests. SCH>SPT>HC trends were observed for all NSS subscale scores and for the left, right, and total NSS scores.

CONCLUSIONS

To our knowledge, the present study is the first to examine NSSs in adolescents with schizophrenia and adolescents with schizotypal personality traits. These results provide preliminary findings suggesting that schizophrenia spectrum disorders may be characterized by developmental abnormalities in the central nervous system, and support the notion that NSSs may be schizophrenia spectrum disorder biomarkers.

Impaired conscious memory in non-clinical schizotypy

INTRODUCTION

Impaired controlled and preserved/enhanced automatic memory processes have been reported in schizotypy. This memory pattern has been considered as a marker of vulnerability to schizophrenia. Our aim was to further explore this memory pattern in non-clinical schizotypy in order to determine which specific dimensions of schizotypy (i.e., positive, negative or disorganised), and more specifically which components of the dimensions, are most closely related to memory dysfunctions.

METHODS

Fifty-seven undergraduate students performed a category-production task. This was adapted for use with the process dissociation procedure in order to dissociate between automatic and controlled memory processes. The level of schizotypy was assessed using the Schizotypal Personality Questionnaire.

RESULTS

Regression analyses confirmed that controlled memory processes decreased as schizotypy increased. The positive factors (more specifically, the ideas of reference subscale) and disorganised factors (more specifically, the odd or eccentric behaviour subscale) were negatively correlated with the controlled memory processes.

CONCLUSIONS

Our study supports the idea that impaired controlled processes are an early cognitive marker of vulnerability to schizophrenia and confirm that the disorganised factor contributes the most to vulnerability to memory dysfunction. It also emphasises the importance of dissociating between each of the features characterising schizotypy rather than considering it as a whole.

Visual-spatial working memory performance and temporal gray matter volume predict schizotypal personality disorder group membership

BACKGROUND

Prior work shows individuals with schizotypal personality disorder (SPD) evince temporal lobe volume abnormalities similar to schizophrenia but sparing of prefrontal cortex, which may mitigate psychosis and the severe neurocognitive impairments observed in schizophrenia. This study examined the extent to which frontal-temporal gray matter volume and neurocognitive performance predict: (1) SPD group membership in a demographically-balanced sample of 51 patients and 37 healthy controls; and (2) symptom severity in SPD.

METHODS

Dimensional gray-matter volume (left frontal-temporal regions (Brodmann area (BA) 10, 21, 22)) and neurocognitive performance on key memory tasks (California Verbal Learning Test (CVLT), Dot Test, Paced Auditory Serial Addition Test (PASAT)), all salient to schizophrenia-spectrum disorders were examined in a multi-variable model.

RESULTS

Middle temporal gyrus (BA21) volume and spatial-working memory (Dot Test) performance were significant predictors of SPD group membership likelihood, with poorer working-memory performance indicating increased probability of SPD membership. Combining across regional volumes or cognitive measures resulted in fair-to-good discrimination of group membership, but including neurocognitive and non-collinear regional volume measures together resulted in a receiver-operating-characteristic (ROC) curve with improved diagnostic discrimination. Larger BA10 volume in dorsolateral prefrontal cortex (DLPFC) significantly predicted less symptom severity in SPD.

CONCLUSIONS

These findings suggest that temporal lobe volume and spatial-working memory performance are promising biological/phenotype markers for likelihood of SPD classification, while greater DLPFC volume may serve as a protective factor.

Spatial analysis of schizotypal personality traits in Chinese male youths: evidence from a GIS-based analysis of Sichuan

Background

Schizotypal personality traits are associated with schizophrenia spectrum disorders, stating that schizotypal traits may represent a “prodrome” or other developmental precursor of schizophrenia. Genetic and environmental factors both play importanxt roles in the development of schizotypal traits. Different levels of schizotypal traits across regions may be indicative of similar differences in the incidence of schizophrenia.

Aim

The present study identifying where in a given region, schizotypal personality traits are more or less level of schizotypal personality scores in Chinese male youth of Sichuan province. Not only for research purposes but also for the evaluation of new draft and allocation policy initiatives intended to aid recruitment of mental health employees.

Methods

Data from the Psychological Selection Systems for Chinese Recruits, a mental health screening system used in China, collected in 2011 (67,558 copies) were used to map spatial distribution of schizotypal personality traits using geostatistics and geographic information system (GIS) techniques. Correlation analyses were conducted to explore the effects of years of education and illiterate rate on schizotypal personality traits.

Results

Maps for three schizotypal personality clinical scales (dissociative, Dit; neurotic, Net and sensitive, Set) showed similar geographical trends. The highest T scores were distributed mainly in the eastern and northern counties of Sichuan, with scores decreasing successively from east to west, with the eastern counties generally showing higher scores. Correlation analysis showed that t-scores of Set were negatively correlated with years of education, whereas t-scores of Net were negatively correlated with illiteracy rate.

Conclusions

Schizotypal personality traits in male youth showed specific geographical trends in Sichuan province, providing some evidence that kriging based on GIS can be used to geographically localize genetic and environmental factors associated with schizotypal personality traits. This approach could be used to help allocate public health resources to specific areas and could also have personnel selection applications.

Schizotypal personality disorder

Early phenomenological descriptions of schizophrenia have acknowledged the existence of milder schizophrenia spectrum disorders characterized by the presence of attenuated symptoms typically present in chronic schizophrenia. The investigation of the schizophrenia spectrum disorders offers an opportunity to elucidate the pathophysiological mechanisms giving rise to schizophrenia. Differences and similarities between subjects with schizotypal personality disorder (SPD), the prototypical schizophrenia personality disorder, and chronic schizophrenia have been investigated with genetic, neurochemical, imaging, and pharmacological techniques. Patients with SPD and the more severely ill patients with chronic schizophrenia share cognitive, social, and attentional deficits hypothesized to result from common neurodevelopmentally based cortical temporal and prefrontal pathology. However, these deficits are milder in SPD patients due to their capacity to recruit other related brain regions to compensate for dysfunctional areas. Individuals with SPD are also less vulnerable to psychosis due to the presence of protective factors mitigating subcortical DA hyperactivity. Given the documented close relationship to other schizophrenic disorders, SPD will be included in the psychosis section of DSM-5 as a schizophrenia spectrum disorder as well as in the personality disorder section.

Neuroimaging findings in schizotypal personality disorder: a systematic review

BACKGROUND

Schizotypal personality disorder is the prototypical schizophrenia-spectrum condition, sharing similar phenomenological, cognitive, genetic, physiological, neurochemical, neuroanatomical and neurofunctional abnormalities with schizophrenia. Investigations into SPD circumvent many confounds inherent to schizophrenia such as medication and institutionalization. Hence, SPD offers a unique vantage point from which to study schizophrenia-spectrum conditions.

METHODS

We systematically reviewed the neuroimaging literature in SPD to establish: (1) whether there are concordant findings in SPD and schizophrenia, possibly reflective of core pathology between the two conditions and (2) whether there are discordant findings in SPD and schizophrenia, possibly reflecting protective factors in the former. The findings are synthesized across structural and functional neuroimaging domains.

RESULTS

A total of 54 studies were identified. Medial temporal lobe structures seem to be compromised in both SPD and schizophrenia. In schizophrenia prefrontal structures are further compromised, whereas in SPD these seem to be larger-than-normal, possibly reflecting a compensatory mechanism. Additional pathology is discussed, including evidence of aberrant subcortical dopaminergic functioning.

CONCLUSIONS

SPD is a schizophrenia-spectrum condition that shares pathology with schizophrenia, but is distinct in showing unique neural findings. Future studies are needed to confirm and localize regions of common and disparate pathology between SPD and schizophrenia.

Functional outcomes, functional capacity, and cognitive impairment in schizotypal personality disorder

BACKGROUND

Individuals with schizotypal personality disorder (SPD) exhibit impaired cognitive functioning in a pattern similar to that found in schizophrenia; less clear is the extent to which these individuals also share schizophrenia patients' impairments in functional capacity and real-world functioning.

METHOD

We evaluated 46 SPD patients, as well as 38 individuals with avoidant personality disorder (AvPD) and 55 healthy controls (HC) on: cognitive functioning, real-world functioning (employment and residential status), and functional capacity (indexed by the UPSA, a performance-based skills assessment).

RESULTS

We found that individuals with SPD exhibited worse performance on both the cognitive battery and the UPSA than the other groups; they were also less likely to be employed and to be living independently. Additionally, cognitive and UPSA performance in the SPD group was intercorrelated to a degree comparable to what has been found in schizophrenia, and this relationship was not present in the AvPD group. Finally, real-world functioning was related to UPSA performance for both patient groups.

CONCLUSIONS

SPD patients exhibit impaired real-world functioning suggesting that these deficits extend across the schizophrenia spectrum. In addition, there is supportive evidence for the validity and importance of performance-based measures such as the UPSA to predict everyday outcomes across the schizophrenia spectrum.

Inferring about individual drug and schizotypy effects on cognitive functioning in polydrug using mephedrone users before and after clubbing

OBJECTIVE

Mephedrone has been recently made illegal in Europe, but little empirical evidence is available on its impact on human cognitive functions. We investigated acute and chronic effects of mephedrone consumption on drug-sensitive cognitive measures, while also accounting for the influence of associated additional drug use and personality features.

METHOD

Twenty-six volunteers from the general population performed tasks measuring verbal learning, verbal fluency and cognitive flexibility before and after a potential drug-taking situation (pre-clubbing and post-clubbing at dance clubs, respectively). Participants also provided information on chronic and recent drug use, schizotypal (Oxford-Liverpool Inventory of Feelings and Experiences) and depressive symptoms (Beck Depression Inventory), sleep pattern and premorbid IQ.

RESULTS

We found that (i) mephedrone users performed worse than non-users pre-clubbing and deteriorated from the pre-clubbing to the post-clubbing assessment; (ii) pre-clubbing cannabis and amphetamine (not mephedrone) use predicted relative cognitive attenuations; (iii) post-clubbing, depression scores predicted relative cognitive attenuations; and (iv) schizotypy was largely unrelated to cognitive functioning, apart from a negative relationship between cognitive disorganisation and verbal fluency.

CONCLUSION

Results suggest that polydrug use and depressive symptoms in the general population negatively affect cognition. For schizotypy, only elevated cognitive disorganisation showed potential links to a pathological cognitive profile previously reported along the psychosis dimension.

Semantic processing impairment in individuals with schizotypal personality disorder features: a preliminary event-related potential study

OBJECTIVE

This study aimed to examine semantic processing features in individuals with and without schizotypal personality disorder (SPD) features.

METHODS

An implicit semantic task was used to examine the automatic spreading semantic activation process which is relatively free from the influence of attention. An explicit semantic task was used to examine the controlled semantic processing which requires high involvement of attention. Individuals with stable SPD features (n=17) were those who scored higher than 36 on the schizotypal personality questionnaire (SPQ) at two time points. Individuals with unstable SPD features (n=15) were defined as participants who scored higher than 36 at the baseline time point but lower than 36 at the second time point. Their performances in the two semantic tasks were then compared to 17 individuals without SPD features (scoring below 36 at both time points). Event-related potentials (ERP) were recorded when participants were performing the two tasks.

RESULTS

Behavioral data, early ERP components and N400s were analyzed in each experiment. No between-group difference was observed in the implicit semantic task. In the explicit semantic task, the differences involved only the N400 component. When compared to the group without SPD features, participants with stable and unstable SPD features showed enhanced N400 effects (difference wave), while there was no difference between the two groups with SPD features. Moreover, the larger N400 effects were found to be due to less negative N400 amplitudes to related target words.

CONCLUSION

These findings suggest that individuals with SPD features were impaired in processing of context-related stimuli. The inhibition function to contextually unrelated materials in participants with SPD features appeared intact.

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.

Cerebellar-dependent eyeblink conditioning deficits in schizophrenia spectrum disorders

Accumulating evidence suggests that abnormalities in neural circuitry and timing associated with the cerebellum may play a role in the pathophysiology of schizophrenia. Schizotypal personality disorder (SPD) may be genetically linked to schizophrenia, but individuals with SPD are freer from potential research confounds and may therefore offer insight into psychophysiological correlates of schizophrenia. The present study employed a delay eyeblink conditioning (EBC) procedure to examine cerebellar-dependent learning in schizophrenia, SPD, and healthy control subjects (n = 18 per group) who were matched for age and gender. The conditioned stimulus was a 400-ms tone that coterminated with a 50 ms unconditioned stimulus air puff. Cognitive performance on the Picture Completion, Digit Symbol Coding, Similarities, and Digit Span subscales of the Wechsler Adult Intelligence Scale--Third Edition was also investigated. The schizophrenia and SPD groups demonstrated robust EBC impairment relative to the control subjects; they had significantly fewer conditioned responses (CRs), as well as smaller CR amplitudes. Schizophrenia subjects showed cognitive impairment across subscales compared with SPD and control subjects; SPD subjects showed intermediate performance to schizophrenia and control subjects and performed significantly worse than controls on Picture Completion. Impaired EBC was significantly related to decreased processing speed in schizophrenia spectrum subjects. These findings support the role of altered cortico-cerebellar-thalamic-cortical circuitry in the pathophysiology of schizophrenia spectrum disorders.

Relationship between personality disorder dimensions and verbal memory functioning in a community population

Based on the Baltimore Epidemiologic Catchment Area (ECA) follow-up survey, we examined relationships between dimensions of Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) personality disorders and both subjective and objective memory functioning in a community population. Our study subjects consisted of 736 individuals from the ECA follow-up study of the original Baltimore ECA cohort, conducted between 1993 and 1996 and available for assessment in the Hopkins Epidemiology Study of Personality Disorders from 1997 to 1999. Subjects were assessed for DSM-IV personality disorders using a semi-structured instrument, the International Personality Disorder Examination, and were asked about a subjective appraisal of memory. Verbal memory function, including immediate recall, delayed recall, and recognition, were also evaluated. Multiple linear regression analyses were used to determine associations between personality dimensions of DSM-IV Axis II traits and subjective and objective memory functioning. Scores on schizoid and schizotypal personality dimensions were associated with subjective and objective memory dysfunction, both with and without adjustment for Axis I disorders. Borderline, antisocial, avoidant, and dependent personality disorder scores were associated with subjective memory impairment only, both with and without adjustment for Axis I disorders. This study suggests that subjective feelings of memory impairment and/or objective memory dysfunction are associated with specific personality disorder dimensions.

Sustained attention and working memory deficits follow a familial pattern in schizophrenia

Cognitive deficits are core features of schizophrenia and considered putative endophenotypes. This study assessed the familial pattern of deficits in sustained attention, working memory and executive function in remitted-schizophrenia patients and their unaffected siblings. Sixteen patients, 16 unaffected siblings, and 17 healthy control subjects underwent a battery of neuropsychological tasks that have so far yielded mixed findings in performance differences. Both groups had prolonged reaction times compared with controls in sustained attention tasks; the siblings made more false alarms in the working memory task, but only the patients' performance was poorer in the executive function tasks. These findings further support sustained attention and working memory deficits as potential endophenotypes of schizophrenia. Reaction time and false alarm rates are suggested as additional useful endophenotypic measures that could potentially account for differences in performance in tasks that are not purported to examine the specific measures per se.

Evidence of reduced selective attention in schizotypal personality disorder

It has been shown that high-schizotypy and schizophrenic participants demonstrate increased task-switching costs, although high-schizotypy participants present this pattern only in incongruent trials (Cimino & Haywood, 2008). In this study, we aim to explore whether this results from difficulties in selective attention or task control. A total of 18 participants with high levels of psychometrically defined schizotypy and 16 participants with low scores were tested in two different versions of a task-switching paradigm. Participants were asked to switch between attending to the color or the shape of bidimensional objects following a previous cue. Two versions of the task were investigated, one involving only switches in the perceptual dimension to attend (color or shape) and another also switching the response set. High-schizotypy subjects consistently showed increased switch costs in incongruent trials for both versions of the tasks, demonstrating a deficit in the selection of the perceptual dimension instead of the selection of the response rules.

Eye tracking performance and the boundaries of the schizophrenia spectrum

In order to investigate the nature of the eye tracking impairment in schizophrenia spectrum we measured pursuit gain with a constant velocity target using a quantitative (RMS error in pursuit gain) and, on an exploratory basis, a qualitative (quality of tracking) measure. We utilized a sample consisting of three clinically characterized groups: patients with schizophrenia (SZ), their first degree non-psychotic relatives, subjects with schizotypal personality disorder (SPD), and healthy volunteers (HV). Thirty three SZ patients, 19 SPD subjects, 66 non-psychotic relatives (all clinically assessed for schizophrenia spectrum psychopathology--DSM-IIIR) and 18 HV were evaluated using an infrared eye tracking system. Targets were constant velocity trapezoids at 5°/s (slow) and 16°/s (fast). The quality of the eye tracking was independently evaluated by at least two raters (ICC: 0.92). The RMS measures at the two velocities (quantitative measure) and the quality of the tracking obtained for each velocity were entered separately into a two factor repeated measures ANOVA, with velocity and diagnosis as the independent measures. For the quantitative ratings (RMS error), a significant effect for velocity was found, with all subjects performing worse at the higher velocity, but there was no significant velocity by diagnosis interaction. In addition, an overall significant effect for diagnosis was found in the four-group ANOVA. In post hoc multiple comparison tests, SZ subjects performed significantly worse from the HV and the relatives. SPD subjects were not different from patients with schizophrenia (or from any group--and their performance was intermediate between the HV and the SZ). Relatives of the patients with schizophrenia were different from SZ subjects, but not different from SPD or HV subjects. Similar results were obtained in the exploratory qualitative ratings. Clinical symptoms did not correlate significantly with quantitative or qualitative performance in any group. We have found that the performance of SPD subjects is intermediate between that of patients with schizophrenia and the healthy volunteers in both qualitative and quantitative (exploratory) measures. Indeed, SPD subjects comprise the only group not statistically different from schizophrenic patients in quantitative or qualitative ratings.

Evolution of neuropsychological dysfunction during the course of schizophrenia and bipolar disorder

BACKGROUND

Neurocognitive dysfunction in schizophrenia (SZ), bipolar (BD) and related disorders represents a core feature of these illnesses, possibly a marker of underlying pathophysiology. Substantial overlap in domains of neuropsychological deficits has been reported among these disorders after illness onset. However, it is unclear whether deficits follow the same longitudinal pre- and post-morbid course across diagnoses. We examine evidence for neurocognitive dysfunction as a core feature of all idiopathic psychotic illnesses, and trace its evolution from pre-morbid and prodromal states through the emergence of overt psychosis and into chronic illness in patients with SZ, BD and related disorders.

METHOD

Articles reporting on neuropsychological functioning in patients with SZ, BD and related disorders before and after illness onset were reviewed. Given the vast literature on these topics and the present focus on cross-diagnostic comparisons, priority was given to primary data papers that assessed cross-diagnostic samples and recent meta-analyses.

RESULTS

Patients with SZ exhibit dysfunction preceding the onset of illness, which becomes more pronounced in the prodrome and early years following diagnosis, then settles into a stable pattern. Patients with BD generally exhibit typical cognitive development pre-morbidly, but demonstrate deficits by first episode that are amplified with worsening symptoms and exacerbations.

CONCLUSIONS

Neuropsychological deficits represent a core feature of SZ and BD; however, their onset and progression differ between diagnostic groups. A lifetime perspective on the evolution of neurocognitive deficits in SZ and BD reveals distinct patterns, and may provide a useful guide to the examination of the pathophysiological processes underpinning these functions across disorders.

Factors in sensory processing of prosody in schizotypal personality disorder: an fMRI experiment

INTRODUCTION

Persons diagnosed with schizophrenia demonstrate deficits in prosody recognition. To examine prosody along the schizophrenia spectrum, antipsychotic-naïve schizotypal personality disorder (SPD) subjects and healthy control subjects were compared. It was hypothesized that SPD subjects would perform more poorly; with cognitive and demographic factors contributing to the poor performance. The superior temporal gyrus (STG) was selected as the region-of-interest (ROI) given its known abnormalities in SPD and its important role in the processing of prosody.

METHODS

SPD and healthy comparison (HC) subjects were matched on age, IQ, and parental social-economic status (PSES). Cognitive measures included the Speech Sound Perception Test (SSPT) to examine phonological processing (SPD=68, HC=74) and the Verbal Fluency task to examine executive functioning (SPD=129, HC=138). The main experiment was a novel fMRI task of prosody identification using semantically neutral sentences spoken with emotional prosody (SPD=16, HC=13). Finally, volumetric measurement of the superior temporal sulcus (STS), a key region for processing prosody, and partially overlapping with the STG, was performed (SPD=30, HC=30).

RESULTS

Phonological processing and executive functioning were both impaired in SPD subjects compared with HC subjects. Contrary to the prediction, SPD subjects, as a group, were similar to HC subjects in terms of correctly indentifying the emotion conveyed and reaction time. Within the SPD group, prosody identification accuracy was influenced by executive functioning, IQ and perhaps PSES, relationships not found with HC subjects. Phonological perception aided prosody identification in both diagnostic groups. As expected, both groups activated the STG while performing the prosody identification task. However, SPD subjects may have been less "efficient" in their recruitment of STG neurons. Finally, SPD subjects demonstrated a trend toward smaller STS volumes on the left, particularly the lower bank.

CONCLUSIONS

These data suggest that subtle differences between SPD and controls in phonological processing, executive functioning, IQ, and possibly PSES, contributed to difficulty in processing prosody for some SPD subjects.

Gamma oscillation deficits and the onset and early progression of schizophrenia

A fascinating convergence of evidence in recent years has implicated the disturbances of neural synchrony in the gamma frequency band (30-100 Hz) as a major pathophysiologic feature of schizophrenia. Evidence suggests that reduced glutamatergic neurotransmission via the N-methyl-D-aspartate (NMDA) receptors that are localized to inhibitory interneurons, perhaps especially the fast-spiking cells that contain the calcium-binding protein parvalbumin (PV), may contribute to gamma band synchrony deficits. These deficits may underlie the brain's failure to integrate information and hence the manifestations of many symptoms and deficits of schizophrenia. Furthermore, because gamma oscillations are thought to provide the temporal structure that is necessary for synaptic plasticity, gamma oscillation deficits may disturb the developmental synaptic reorganization process that is occurring during the period of late adolescence and early adulthood. This disturbance may contribute to the onset of schizophrenia and the functional deterioration that is characteristic of the early stage of the illness. Finally, reduced NMDA neurotransmission on inhibitory interneurons, including the PV-containing cells, may inflict excitotoxic or oxidative injury to downstream pyramidal neurons, leading to further loss of synapses and dendritic branchings. Hence, a key element in the conceptualization of rational early-intervention and prevention strategies for schizophrenia may involve correcting the abnormal NMDA neurotransmission on inhibitory interneurons-possibly that on the PV-containing neurons, in particular-thereby normalizing gamma oscillation deficits and attenuating downstream neuronal pathology.

Indices of orbitofrontal and prefrontal function in Cluster B and Cluster C personality disorders

Neuropsychological studies implicate disruption of frontal systems in personality disorders. Few studies have examined the performance of Cluster B and Cluster C personality disorder patients on tests of orbitofrontal (OFC) and prefrontal (PFC) cortex function. Patients carrying diagnoses of either Cluster B (n=56) or Cluster C (n=19) personality disorders were compared with healthy control subjects (n=61) on the Iowa Gambling Task and University of Pennsylvania Smell Identification Test. They also completed the Wechsler Abbreviated Scale of Intelligence as a control for general intellectual ability. On the gambling task, Cluster B and Cluster C patients made more disadvantageous decisions during certain portions of the task but overall did not differ from healthy controls. Whereas no appreciable differences in olfactory identification performances were detected between patient and healthy control groups, IQ was higher for controls and was related to Cluster B patients' lower educational levels. Overall, there was limited evidence for neurocognitive inefficiency for personality disorder groups on tests sensitive to OFC and PFC function. The present study is among the first to report neurocognitive findings for the full range of Cluster B personality disorders and any Cluster C personality disorder.

Dichotic listening in schizotypal personality disorder: evidence for gender and laterality effects

Verbal dichotic listening performance was examined in 42 right-handed men and women with DSM-IV-defined schizotypal personality disorder (SPD) and 68 right-handed controls. As expected, both male and female control groups showed a right ear advantage on a verbal dichotic listening task. Although SPD subjects in general had lower accuracy scores than comparison subjects, only male SPD subjects showed an abnormal left ear advantage that was specifically due to deficient right ear performance. The results suggest that left hemisphere temporal lobe structures may be particularly involved in male, but not female, SPD.

Neurodevelopmental factors associated with schizotypal symptoms among adolescents at risk for schizophrenia

Schizophrenia has come to be viewed as a neurodevelopmental disorder that is characterized by genetic vulnerability, stressors during the prenatal period that may be marked by minor physical anomalies and neurobehavioral deficits that emerge in early development. Less is known about the neurodevelopmental origins of schizotypal personality symptoms. The present study examines schizotypal symptoms in Israeli adolescents (mean age = 16.79 years) who have not yet reached the developmental period during which first schizophrenic episode is most likely to emerge: 39 adolescent offspring of parents with schizophrenia, 39 offspring of parents with other psychiatric disorders, and 36 offspring of parents with no history of mental illness. The Semi-Structured Kiddie Interview for Personality Syndromes was used to assess cognitive–perceptual, interpersonal, and disorganized schizotypal symptoms. Interpersonal schizotypal symptoms were more prevalent in the schizophrenia offspring group than in the no-mental-illness offspring group. Among the schizophrenia offspring group, interpersonal, but not cognitive–perceptual, schizotypal symptoms were associated with minor physical anomalies, fine motor dyscoordination, and deficits in executive functioning during adolescence. Among young people whose parents did not have schizophrenia, cognitive–perceptual schizotypal symptoms were correlated with deficits in executive functioning. Adolescent schizotypal symptoms were associated with neurobehavioral symptoms measured during middle childhood in a subgroup of the sample that had been assessed prospectively. Finally, young people who had genetic risk for schizophrenia, minor physical anomalies, and neurobehavioral signs together were at markedly increased risk for symptoms of interpersonal schizotypal symptoms, compared to young people with one or none of these risk factors.

Schizotypal traits and cognitive function in healthy adults

Growing evidence has shown that psychometrically identified schizotypes among student populations have subtle cognitive impairments in several domains such as attention, working memory and executive function, but the possible association between psychometric schizotypy in adult populations and cognitive function has not been well documented. Here we examined the association between schizotypal traits as assessed by the Schizotypal Personality Questionnaire (SPQ) and cognitive function including memory, attention, executive function, and general intelligence in 124 healthy adults. Cognitive functioning was assessed with the Wechsler Memory Scale-Revised (WMS-R), the Wechsler Adult Intelligence Scale-Revised (WAIS-R), and the Wisconsin Card Sorting Test (WCST). SPQ scores showed a significant inverse correlation with verbal IQ and the information, comprehension and similarities subtests. No correlation was found between SPQ scores and memory, attention, performance IQ, or executive functioning. These results indicate that schizotypal traits in healthy adults are associated with verbal IQ decrements, suggesting that schizotypal traits themselves, even at a non-clinical level, may play unfavorable roles in cognitive functioning, which is in line with the viewpoint that schizotypy is on a continuum with normality, with its extreme form being clinically expressed as schizophrenia.

Prospective memory deficits in subjects with schizophrenia spectrum disorders: a comparison study with schizophrenic subjects, psychometrically defined schizotypal subjects, and healthy controls

Memory impairment is one of the core deficits in schizophrenia. This study explored the memory profiles of schizophrenic and psychometrically defined schizotypal subjects. The study participants included 15 patients with schizophrenia, 41 schizotypal subjects, and 20 healthy controls. All of the participants completed verbal and visual memory, working memory, and prospective memory tasks. The results showed that patients with schizophrenia were impaired in all aspects of memory function, whereas the schizotypal subjects tended to show moderate to large impairment effect sizes in prospective memory. It is suggested that prospective memory be considered a potential endophenotype of schizophrenia.

Auditory processing abnormalities in schizotypal personality disorder: an fMRI experiment using tones of deviant pitch and duration

BACKGROUND

One of the cardinal features of schizotypal personality disorder (SPD) is language abnormalities. The focus of this study was to determine whether or not there are also processing abnormalities of pure tones differing in pitch and duration in SPD.

METHODS

Thirteen neuroleptic-naïve male subjects met full criteria for SPD and were group-matched on age and parental socio-economic status to 13 comparison subjects. Verbal learning was measured with the California Verbal Learning Test. Heschl's gyrus volumes were measured using structural MRI. Whole-brain fMRI activation patterns in an auditory task of listening to tones including pitch and duration deviants were compared between SPD and control subjects. In a second and separate ROI analysis we found that peak activation in superior temporal gyrus (STG), Brodmann Areas 41 and 42, was correlated with verbal learning and clinical measures derived from the SCID-II interview.

RESULTS

In the region of the STG, SPD subjects demonstrated more activation to pitch deviants bilaterally (p<0.001); and to duration deviants in the left hemisphere (p=0.005) (two-sample t). SPD subjects also showed more bilateral parietal cortex activation to duration deviants. In no region did comparison subjects activate more than SPD subjects in either experiment. Exploratory correlations for SPD subjects suggest a relationship between peak activation on the right for deviant tones in the pitch experiment with odd speech and impaired verbal learning. There was no difference between groups on Heschl's gyrus volume.

CONCLUSIONS

These data suggest that SPD subjects have inefficient or hyper-responsive processing of pure tones both in terms of pitch and duration deviance that is not attributable to smaller Heschl's gyrus volumes. Finally, these auditory processing abnormalities may have significance for the odd speech heard in some SPD subjects and downstream language and verbal learning deficits.

Awareness of everyday executive difficulties precede overt executive dysfunction in schizotypal subjects

Much evidence indicates that schizophrenic patients exhibit deficits on tests of executive functioning. It is therefore hypothesized that individuals with high schizotypal personality traits that may have a predisposition to schizophrenia, are also likely to exhibit impairments in neuropsychological tests of executive function. The sample consisted of 65 healthy controls that were divided into high and low scorers on the Schizotypal Personality Questionnaire (SPQ-B: Raine et al., 1995). Participants completed a battery of executive tasks (category and letter fluency, the Hayling test, Zoo map); however, a MANOVA revealed no significant differences between high and low SPQ scorers. Nevertheless, high SPQ scorers scored significantly higher on the Dysexecutive Questionnaire (DEX) self-rating scale of everyday executive problems; and these self-ratings correlated significantly with the disorganisation and cognitive-perceptual features of the SPQ-B, but not with the interpersonal features. This suggests that perceived executive dysfunction is pre-morbidly present and may become evident in test performance only with the onset of schizophrenia itself.

Context processing in schizotypal personality disorder: evidence of specificity of impairment to the schizophrenia spectrum

Working memory abnormalities, which are particularly pronounced on context processing tasks, appear relatively specific to schizophrenia spectrum illnesses compared with other psychotic disorders. However, the specificity of context processing deficits to schizotypal personality disorder (SPD), a prototype of schizophrenia, has not been studied. The authors administered 3 versions of the modified AX Continuous Performance Test and an N-back working memory test to 63 individuals with SPD and 25 with other personality disorders, as well as 42 healthy controls. For the AX Continuous Performance Test standard and degraded versions, there was a significant Trial Type x Delay x Group interaction, as SPDs made significantly more errors reflecting poor maintenance of context and fewer errors reflecting good maintenance of context. SPDs also demonstrated poor performance on the N-back, especially at the 2-back condition. Context processing errors and N-back accuracy scores were related to disorganization symptoms. These findings, which are quite similar to those previously reported in patients with schizophrenia, suggest that context processing deficits are specific to the schizophrenia spectrum and are not a reflection of overall psychopathology.

Impact of coexistent schizotypal personality traits on frontal lobe function in obsessive-compulsive disorder

OBJECTIVE

This study was a post-hoc analysis of the results from a neuropsychological battery which was conducted to investigate the frontal lobe difference between obsessive-compulsive disorder (OCD) patients with and without schizotypal personality trait (SPT), especially dorsolateral prefrontal and medial frontal functions.

METHODS

Fifty-five OCD patients were divided into two groups according to their Personality Disorder Questionnaire-4+ scores. Patients with OCD with SPT (n=17) and OCD without SPT (n=38) were compared to 52 schizophrenia patients and 67 healthy subjects. Two neuropsychological tasks, the Wisconsin Card Sorting Test (WCST) and verbal fluency tests which are considered to reflect dorsolateral and medial frontal functions, were selected for an analysis.

RESULTS

OCD with SPT patients and patients with schizophrenia performed significantly worse than controls in both the WCST and verbal fluency tasks, whereas OCD without SPT patients showed no deficits in the same tasks. Moreover, we found no statistically significant difference in either task between patients having OCD with SPT and patients with schizophrenia.

CONCLUSION

This study indicate that OCD with SPT may have distinct patterns of neurocognitive deficit that differ from those of OCD without SPT, especially in terms of frontal lobe function.

Cognitive alterations in groups at risk for psychosis: neutral markers of genetic risk or indicators of social disability?

OBJECTIVE

To investigate whether cognitive alterations associated with vulnerability to psychosis, are associated with expression of psychopathology and functional outcome in groups at different levels of risk for psychotic illness.

METHOD

Neurocognition, psychopathology and functional outcome were measured in subjects with variable risk for psychosis: i) 29 patients with psychotic disorder, ii) 46 subjects at familial risk, iii) 41 subjects at psychometric risk and iv) 54 control subjects.

RESULTS

Dose-response relationships between cognitive dysfunction and increasing risk for psychosis were found. Cognitive alterations were predicted by negative symptoms in patients and by positive psychotic experiences in the familial risk group. In both at risk groups, cognitive speed was associated with functional outcome.

CONCLUSION

Some cognitive impairments serve as neutral endophenotypic marker across the psychosis continuum. However, other cognitive alterations associated with transmission of psychosis may have a direct impact on the pathway from risk to psychopathology and alterations in functioning.

Neurocognitive deficits in the (putative) prodrome and first episode of psychosis

OBJECTIVE

International research programs have contributed to the creation of operationally defined criteria to identify individuals at risk for schizophrenia. Although there has been substantial progress in the prospective study of the schizophrenia prodrome, the utility of current diagnostic criteria remains questionable because of the relatively low base rates of incident psychoses, the high false-positive rate and ethical concerns regarding the treatment of individuals at risk. The identification of brain based neurocognitive vulnerability markers for schizophrenia may contribute to the development of an at risk algorithm with greater predictive accuracy.

METHODS

Forty subjects at risk (AR) for schizophrenia, 15 in their first episode (FE) of schizophrenia, and 36 healthy comparison (HC) subjects were administered a neurocognitive battery that assessed the domains of processing speed, working memory, verbal episodic memory, executive functioning and general intelligence.

RESULTS

At baseline, AR subjects showed neurocognitive deficits across all domains compared to HC subjects that were less severe than those observed in the FE sample. In preliminary analyses, AR subjects who later converted to psychosis (N=5) had greater neurocognitive impairment at baseline evaluation compared to those individuals who remained "at risk" at follow-up.

CONCLUSIONS

Neurocognitive deficits may be important in the pathogenesis of early psychosis and could help to define individuals at greatest risk for schizophrenia. Continued research in larger cohorts is needed to test the validity of this neurocognitive profile and its utility as a vulnerability marker.

Schizotypal disorder and schizophrenia: a profile analysis of neuropsychological functioning in Japanese patients

This study compares neuropsychological functioning in a Japanese schizophrenia spectrum disorder group and a group of healthy Japanese volunteers. Participants were 37 patients diagnosed with schizophrenia, 28 schizotypal patients, and 99 psychiatrically-normal volunteers. A wide range of cognitive measures were examined. All participants completed a Japanese version of a neuropsychological battery assessing executive function, working memory, processing speed, language, verbal memory, and spatial organization. Comparisons of neuropsychological function demonstrated similarities and differences between patients diagnosed with schizotypal disorder and those diagnosed with schizophrenia. Impairments in verbal memory, language, and processing speed were common to both patient groups and may represent a vulnerability to schizophrenia. Impairments in aspects of working memory, spatial organization and executive function were preferentially observed in schizophrenia and may be features of the overt manifestation of psychosis. Possible differences in the contributions of prefrontal and temporo-limbic structures provide direction for further studies.

The effects of guanfacine on context processing abnormalities in schizotypal personality disorder

BACKGROUND

The signature of impaired cognition in people with schizotypal personality disorder (SPD) may be centrally related to working memory impairments. Guanfacine, an alpha2A agonist that acts post-synaptically in the prefrontal cortex (PFC), has shown potential for reducing working memory limitations in other populations. This study examined the potential of guanfacine for improving context processing, a feature of working memory, in SPD.

METHODS

29 individuals with SPD entered into a 4-week, randomized parallel-design, double-blind, placebo-controlled trial of guanfacine treatment, followed by a 4-week open-label extension. A modified version of the AX-Continuous Performance Test (AX-CPT) was administered. On this task, evidence of intact context processing includes few BX errors (false cue, correct probe) and higher levels of AY errors (correct cue, false probe).

RESULTS

At the end of double-blind treatment, participants treated with guanfacine demonstrated a significant reduction in BX errors and a small but significant increase in AY errors, a pattern that was not seen in the participants treated with placebo.

CONCLUSIONS

SPD participants improved in their context processing toward a normal response bias, making fewer BX and more AY errors, after being treated with guanfacine.

Schizophrenic-like neurocognitive deficits in children and adolescents with 22q11 deletion syndrome

22q11.2 Deletion Syndrome (22q11DS) is the most common genetic microdeletion syndrome affecting humans. The syndrome is associated with general cognitive impairments and specific deficits in visual-spatial ability, non-verbal reasoning, and planning skills. 22q11DS is also associated with behavioral and psychiatric abnormalities, including a markedly elevated risk for schizophrenia. Research findings indicate that people with schizophrenia, as well as those identified as schizoptypic, show specific cognitive deficits in the areas of sustained attention, executive functioning, and verbal working memory. The present study examined such schizophrenic-like cognitive deficits in children and adolescents with 22q11DS (n = 26) and controls (n = 25) using a cross-sectional design. As hypothesized, 22q11DS participants exhibited deficits in intelligence, achievement, sustained attention, executive functioning, and verbal working memory compared to controls. Furthermore, deficits in attention and executive functioning were more pronounced in the 22q11DS sample relative to general cognitive impairment. These findings suggest that the same pattern of neuropsychological impairment seen in patients with schizophrenia is present in non-psychotic children identified as at-risk for the development of schizophrenia based on a known genetic risk marker.

Theory of mind, neurocognition, and functional status in schizotypy

The present study is the first to concurrently examine social cognition, neurocognition, and social functioning in psychometric schizotypes. Screening of 2108 undergraduates with the Schizotypal Personality Questionnaire-Brief (SPQ-B) identified 52 persons high in schizotypy and 40 persons low in schizotypy. All participants were administered a test battery designed to assess two elements of neurocognition, verbal secondary memory (California Verbal Learning Test) and executive functioning (Wisconsin Card Sorting Test), two elements of social cognition, emotion perception (The Awareness of Social Inference Test-Part 1) and theory of mind (The Awareness of Social Inference Test-Parts 2 and 3), and social functioning (Social Adjustment Scale-Self Report). Although the persons with high schizotypy were impaired in social functioning relative to the persons with low schizotypy, they were not impaired in theory of mind, emotion perception, verbal secondary memory, or executive functioning. Theory of mind and verbal secondary memory were correlated in persons with high schizotypy. The present findings suggest that psychometric schizotypes are not impaired in the domains of social cognition and neurocognition examined.

MRI abnormalities of the hippocampus and cavum septi pellucidi in females with schizotypal personality disorder

OBJECTIVE

This study examined MRI hippocampal volume and cavum septi pellucidi (CSP) in female subjects with schizotypal personality disorder (SPD) and comparison subjects.

METHOD

MRI was performed on 20 SPD and 29 comparison subjects with delineation of left and right hippocampi. Number of slices containing the CSP was counted. Subjects were given a working memory task, the Delayed Alternation task and other measures of working memory including the Wechsler Memory Test-Revised and the California Verbal Learning Test. Clinical measures were derived from the SCID-II.

RESULTS

SPD females evinced bilaterally smaller hippocampal volumes compared with non-psychiatric female subjects (15.1% on left, 15.7% on right). Additionally, SPD subjects showed statistically significantly more slices containing CSP, and a trend level difference when large CSP was defined as four or more slices (20% vs. 6.9%). SPD subjects demonstrated more errors, more perseverations, and a trend toward more failure to maintain set on the Delayed Alternating task, which were associated with smaller left hippocampal volumes. There was no difference between groups in logical memory, verbal learning or semantic clustering nor a significant correlation between these measures and hippocampal volumes. Clinically, in SPD subjects, right hippocampal volumes correlated negatively with odd appearance/behavior and positively with suspiciousness/paranoia, and odd speech was positively correlated with the number of slices containing a CSP in exploratory analyses.

CONCLUSIONS

Female SPD subjects showed bilaterally smaller hippocampal volumes and larger CSP than comparison subjects, similar to what has been shown in schizophrenia. Moreover, these abnormalities have clinically significant associations which may help to explain some of the manifestations of the disorder.

Comparison of three computer-administered cognitive tasks as putative endophenotypes of schizophrenia

It has been repeatedly demonstrated that individuals with schizotypal personality features (SPF) exhibit similar endophenotypic traits as persons with schizophrenia. Less research has compared the relative sensitivity of different endophenotypes in the same sample of individuals with SPF. Fourteen university students with SPF (mean age 20.5+/-1.6; 43% male) and 26 controls (mean age 20.3+/-1.1; 31% male) were defined by the Abbreviated Schizotypal Personality Questionnaire (SPQ-B). All participants reported no known biological relative with schizophrenia. Participants completed three computer-administered cognitive tasks: a 6-min degraded-stimuli A-X Continuous Performance Test (CPT), the Wisconsin Card Sort Test (WCST), and a Span of Apprehension (SOA) task (6- and 12-letter arrays). On the CPT, only omission errors resulted in a statistically significant group difference, U=115.5, p=.05, Cohen's d=0.54 (medium effect size), with the SPF group (mean errors: 3.43+/-3.28) making more omission errors than controls (mean errors: 1.88+/-2.66). Notably, 46% of the controls had no omission errors, compared to 14% of the SPF group. The only SPQ-B factor score to show a statistically significant linear relationship with CPT omission errors was the Cognitive-Perceptual factor (rs=.33, p=.04). Group differences on performance indices from the SOA and WCST did not approach statistical significance. Based on performance from the community-identified schizotypes, results suggest that performance on the CPT may represent a more robust endophenotype of schizophrenia, compared to the SOA and WCST.

Cognitive function and symptoms in adolescents with schizotypal personality disorder

Cognitive deficits have been documented in schizophrenia and spectrum disorders. This study examines cognitive functioning and its relation to symptoms in adolescents with schizotypal personality disorder (SPD). Participants are 89 adolescents recruited for a study of youth at risk for Axis I disorders, especially psychosis. At intake, 34 met criteria for SPD, 38 for another Axis II disorder and/or conduct disorder (Other disorder-OD), and 17 did not currently meet criteria for any DSM-IV disorder (normal control-NC). At initial assessment, cognitive functioning was measured using subtests from the Wechsler Intelligence Scales and Wechsler Memory Scales (WMS), and symptoms were measured using the Structured Interview for Prodromal Symptoms (SIPS). At the time of this report, 50 were readministered the SIPS at 1-year follow-up (T2). The SPD group scored significantly below the NC group on the Arithmetic subtest of the Wechsler Intelligence Scales, but there was only limited evidence of group differences on the WMS. Poorer performance on the Wechsler Intelligence Scales was associated with greater severity of negative and disorganized symptoms. Deficits on the WMS were linked with more severe disorganized symptoms. The findings reported here are consistent with previous reports of limited cognitive deficits in adolescents with SPD, with the most marked deficits in mental arithmetic. The associations between symptoms and cognitive scores parallel those observed in adults with schizophrenia and spectrum disorder, and they are consistent with the notion that negative symptoms are more stable and partially reflect premorbid cognitive functions.

Reduction of caudate nucleus volumes in neuroleptic-naïve female subjects with schizotypal personality disorder

BACKGROUND

The caudate nucleus might contribute to the psychopathological and cognitive deficits observed in schizotypal personality disorder (SPD), a schizophrenia spectrum disorder. Here we focused on female patients, because this group is underrepresented in studies of SPD and schizophrenia, and we might learn more about the caudate and clinical and cognitive impairments that are unique to female patients diagnosed with SPD.

METHODS

Magnetic resonance imaging scans, obtained on a 1.5-T magnet with 1.5-mm contiguous slices, were used to measure the caudate in 32 neuroleptic-naïve women with SPD and in 29 female normal comparison subjects. Subjects were group-matched for age, parental socioeconomic status, and intelligence quotient.

RESULTS

We found significantly reduced left and right caudate relative volume (8.3%, 7.7%) in female SPD subjects compared with normal comparison subjects. In female SPD subjects, we found significant correlations between smaller total caudate relative volume and worse performance on the Wisconsin Card Sorting test (nonperseverative errors) and on the California Verbal Learning Test (verbal memory and learning), and significant correlations between smaller total caudate relative volume and both positive and negative symptoms on the Structured Interview for Schizotypy.

CONCLUSIONS

These findings demonstrate that, for female SPD subjects, smaller caudate volume is associated with poorer cognitive performance and more schizotypal symptomatology.

Premorbid neurocognitive functioning in schizophrenia spectrum disorder

A prospective study based on the U.S. National Collaborative Perinatal Project and using the Wechsler Intelligence Scale for Children (WISC) found lower test scores for the Coding subtest in preschizophrenic children than in their unaffected siblings. Using data on cognitive functioning in adolescence, the aim of the present prospective study was to examine whether low scores on Coding is associated with the risk of developing schizophrenia spectrum disorders. The 12 subtests of the WISC were administered to 311 children and adolescents with a mean age of 15.1 years (range: 8 to 20 years), and the diagnostic assessment (DSM-IIIR) was conducted by senior clinicians 25 years later. The group with schizophrenia spectrum disorder consisted of 84 individuals, and this group obtained significantly lower scores on Coding than nonschizophrenic controls. This difference could not be explained by differences in WISC IQ. Logistic regression analysis controlling for age at examination, gender, and social status yielded a significant, but relatively weak, association between low Coding test score and risk of schizophrenia spectrum disorder. For each unit increase in the Coding raw score, the adjusted odds ratio was 0.97 (95% CI 0.94-1.00) (p = .022), and the risk of schizophrenia spectrum disorder decreased by 3% (95% CI 6 to 0%). The Coding deficit on the WISC may indicate deficits in perceptual motor speed or in working memory processing speed in young individuals who later develop schizophrenia, schizotypal personality disorder, or other disorders within the schizophrenia spectrum.

Catechol-O-methyltransferase Val158Met genotype variation is associated with prefrontal-dependent task performance in schizotypal personality disorder patients and comparison groups

OBJECTIVE

A single-nucleotide polymorphism of the gene coding for catechol-O-methyltransferase (COMT Val(158)Met) is associated with prefrontal-dependent task performance in schizophrenia. We evaluated the relationship of the COMT genotype with diagnostic status and cognitive performance in schizotypal personality disorder.

METHODS

Unmedicated outpatients with schizotypal personality disorder (SPD; n = 67) and non-schizotypal personality disorder (NSPD; n = 154) by DSM-III-R, and normal control (NC; n = 60) participants were genotyped at the COMT Val(158)Met locus. Of these, 98 Caucasians (23 SPD, 52 NSPD and 23 NC) performed a brief neurocognitive battery: Wisconsin Card Sorting Test (WCST), Paced Auditory Serial Addition Test (PASAT), California Verbal Learning Test (CVLT), Visuospatial Working Memory (DOT) and Visual Delayed Recall (Wechsler Memory Scale Visual Reproduction, WMS-VR).

RESULTS

Allele distribution was not significantly different in the full sample (by chi(2)) for the SPD group compared with either the NC or combined NC/NSPD groups. In analyses of variance of Caucasian individuals, the SPD group performance met or approached significantly worse performance than NC, NSPD or both groups, on the PASAT, CVLT and WMS-VR. In regression analyses of cognitive performance, the COMT genotype was significantly associated with performance on WCST and PASAT, independent of diagnosis, with the Val/Val genotype associated with the worse performance.

CONCLUSIONS

(1) Allelic variation in COMT activity is unrelated to the diagnosis of SPD in this sample. (2) Individuals with SPD exhibit multiple deficits in prefrontal and temporal lobe-dependent tasks. (3) The COMT genotype is related to performance on prefrontal cortex-dependent tasks and may contribute to the deficit in prefrontal-dependent memory processes in SPD as it does in schizophrenia.

Clinical, cognitive, and social characteristics of a sample of neuroleptic-naive persons with schizotypal personality disorder

INTRODUCTION

Schizotypal personality disorder (SPD) shares with schizophrenia many biological features, yet little is known about the clinical characteristics of persons diagnosed with this disorder. This report describes the clinical, cognitive and socio-occupational characteristics of a community sample of subjects diagnosed with SPD.

METHOD

Sixty-four male and 40 female neuroleptic-naive DSM-IV SPD subjects and 59 male and 51 female comparison subjects were recruited from the community for a total sample of 214 subjects. Demographic and cognitive differences between groups and, within the SPD group, the effect of gender on clinical features, such as the SPD criteria, SAPS, SANS, Schizotypal Personality Questionnaire, and co-morbidity, were examined using ANOVA and Chi-square distributions.

RESULTS

SPD subjects, in contrast to comparison subjects, had significantly lower socio-economic status, poorer social relationships and skills, and lower vocabulary scores. Furthermore, SPD subjects demonstrated more impairment on Vocabulary scores than on Block Design, as measured by the WAIS-R, a pattern not seen in comparison subjects. In the SPD cohort, positive symptoms predominated and nearly half were co-morbid for major depression. With respect to gender, male SPD subjects, compared with female SPD subjects, evinced significantly more negative symptoms, fewer friends, had more odd speech, and were more likely to also suffer from paranoid and narcissistic personality disorders. In contrast to male SPD subjects, female SPD subjects perceived themselves to be more disorganized.

CONCLUSIONS

SPD subjects, similar to schizophrenics, are impaired socially, occupationally, and cognitively, particularly in the area of verbal measures. Moreover, male SPD subjects may be more severely affected than female SPD subjects across multiple domains of functioning.

Fronto-temporal disconnectivity in schizotypal personality disorder: a diffusion tensor imaging study

BACKGROUND

Using diffusion tensor imaging (DTI), we previously reported abnormalities in two critical white matter tracts in schizophrenia, the uncinate fasciculus (UF) and the cingulum bundle (CB), both related to fronto-temporal connectivity. Here, we investigate these two bundles in unmedicated subjects with schizotypal personality disorder (SPD).

METHODS

Fifteen male SPD subjects and 15 male control subjects were scanned with line-scan DTI. Fractional anisotropy (FA) and mean diffusivity (D(m)) were used to quantify water diffusion, and cross-sectional area was defined with a directional threshold method. Exploratory correlation analyses were evaluated with Spearman's rho, followed by post hoc hierarchical regression analyses.

RESULTS

We found bilaterally reduced FA in the UF of SPD subjects. For CB, there was no significant group difference for FA or D(m) measures. Additionally, in SPD, reduced FA in the right UF was correlated with clinical symptoms, including ideas of reference, suspiciousness, restricted affect, and social anxiety. In contrast, left UF area was correlated with measures of cognitive function, including general intelligence, verbal and visual memory, and executive performance.

CONCLUSIONS

These findings in SPD suggest altered fronto-temporal connectivity through the UF, similar to findings in schizophrenia, and intact neocortical-limbic connectivity through the CB, in marked contrast with what has been reported in schizophrenia.

A comparative profile analysis of neuropsychological function in men and women with schizotypal personality disorder

The purpose of this study was to compare the cognitive profiles of men and women with clinically defined schizotypal personality disorder (SPD). We examined the neuropsychological profile of SPD in 26 right-handed females and 31 right-handed males who met DSM-IV criteria for SPD, and matched comparison subjects. Cognitive performance was assessed on measures of abstraction, verbal and spatial intelligence, learning and memory, language, attention, and motor skills. Neuropsychological profiles were constructed by standardizing test scores based on the means and standard deviations of comparison groups matched for sex, age, handedness, ethnicity and parental SES. Overall, SPD subjects showed mild, general decrements in performance in most cognitive domains. However, unlike male SPD subjects, female SPDs did not show relative deficits in verbal learning and abstraction. The results suggest a less severe pattern of cognitive deficits in women with SPD compared to men, consistent with hypotheses of gender differences in cognitive function in schizophrenia.

Validation of Turkish and English Versions of the Schizotypal Personality Questionnaire-B

Abstract. We present normative data for a Turkish translation of the Schizotypal Personality Questionnaire-B (SPQ-B). The SPQ-B is a brief, self-report screening instrument developed by Raine and Benishay (1995) and is used to evaluate respondents for the presence of schizotypal personality features. We describe the internal consistency and test-retest reliability of the Turkish instrument and report intercorrelations among subfactors and total SPQ-B score. For comparison purposes, we present normative data for the SPQ-B (English version) from two studies examining schizotypy among nonclinical student samples in the United States. We report α coefficients and assess the convergent validity of the SPQ-B by examining the relationship between scores on the SPQ-B and performance on two existing measures of schizotypy and schizophrenic-spectrum personality disorders. Central tendency, distribution of scores, factor structure, and intercorrelations in both Turkish and US samples were similar, suggesting that our Turkish translation of the SPQ-B is a culturally valid instrument.

Cingulate gyrus volume and metabolism in the schizophrenia spectrum

BACKGROUND

The cingulate gyrus, which is involved in affect, attention, memory and higher executive functions, has been implicated as a dysfunctional region in schizophrenia. Postmortem studies report cytoarchitectural changes in the anterior cingulate gyrus (ACG) and functioning imaging studies show correlations between the degree of hypometabolism of the anterior cingulate and clinical symptoms in schizophrenia.

METHODS

Unmedicated patients with schizophrenia (n=27) and schizotypal personality disorder (SPD) (n=13), as well as sex- and age-matched control subjects (n=32), were studied with (18)F-fluorodeoxyglucose positron emission tomography (PET) scans and magnetic resonance imaging (MRI). As a control over mental activity, all subjects performed a verbal working memory task during the PET protocol. The cingulate gyrus was first outlined on the MRI scans and, after coregistration, the coordinates were applied to the PET scans to yield a three-dimensional metabolic map of the cingulate gyrus for each subject. A statistical resampling method was used to analyze the metabolic differences between groups.

RESULTS

Compared with controls, patients with schizophrenia had lower relative glucose metabolic rates in the left anterior cingulate and the right posterior cingulate gyrus (PCG) assessed by 3-D significance probability mapping. SPD patients had higher glucose metabolic rates (GMRs) in the left posterior cingulate than did controls. Furthermore, volumetric measurement with MRI showed the left anterior cingulate and Brodmann area 24' to be smaller in schizophrenic patients than controls.

CONCLUSIONS

Compared with controls, patients with schizophrenia have metabolic and volumetric reductions in a cingulate gyrus area that is related to higher executive functions. Schizotypal patients rely more on sensory association areas to perform a cognitive task than do controls and seem to be a group that is partially distinct in its physiological and functional characteristics.