Resting state alpha oscillatory activity is a valid and reliable marker of schizotypy.

Schizophrenia is among the most debilitating neuropsychiatric disorders. However, clear neurophysiological markers that would identify at-risk individuals represent still an unknown. The aim of this study was to investigate possible alterations in the resting alpha oscillatory activity in normal population high on schizotypy trait, a physiological condition known to be severely altered in patients with schizophrenia. Direct comparison of resting-state EEG oscillatory activity between Low and High Schizotypy Group (LSG and HSG) has revealed a clear right hemisphere alteration in alpha activity of the HSG. Specifically, HSG shows a significant slowing down of right hemisphere posterior alpha frequency and an altered distribution of its amplitude, with a tendency towards a reduction in the right hemisphere in comparison to LSG. Furthermore, altered and reduced connectivity in the right fronto-parietal network within the alpha range was found in the HSG. Crucially, a trained pattern classifier based on these indices of alpha activity was able to successfully differentiate HSG from LSG on tested participants further confirming the specific importance of right hemispheric alpha activity and intrahemispheric functional connectivity. By combining alpha activity and connectivity measures with a machine learning predictive model optimized in a nested stratified cross-validation loop, current research offers a promising clinical tool able to identify individuals at-risk of developing psychosis (i.e., high schizotypy individuals).

Exploring schizophrenia spectrum psychopathology in borderline personality disorder.

We have previously argued that the current borderline personality disorder (BPD) diagnosis is over-inclusive and clinically and conceptually impossible to distinguish from the schizophrenia spectrum disorders. This study involves 30 patients clinically diagnosed with BPD as their main diagnosis by three BPD dedicated outpatient treatment facilities in Denmark. The patients underwent a careful and time-consuming psychiatric evaluation involving several senior level clinical psychiatrists and researchers and a comprehensive battery of psychopathological scales. The study found that the vast majority of patients (67% in DSM-5 and 77% in ICD-10) in fact met the criteria for a schizophrenia spectrum disorder, i.e., schizophrenia (20%) or schizotypal (personality) disorder (SPD). The schizophrenia spectrum group scored significantly higher on the level of disorders of core self as measured by the Examination of Anomalous Self-Experiences Scale (EASE). The BPD criterion of "identity disturbance" was significantly correlated with the mean total score of EASE. These findings are discussed in the light of changes from prototypical to polythetic diagnostic systems. We argue that the original prototypes/gestalts informing the creation of BPD and SPD have gone into oblivion during the evolution of polythetic criteria.

A diagnostic classification version of Schizotypal Personality Questionnaire using diagnostic classification models.

OBJECTIVE: To obtain more precise and rich information from the measurements for schizotypal personality disorder (SPD), a cutting-edge psychometric theory called diagnostic classification models (DCMs) was first employed in the present study to develop a diagnostic classification version of the Schizotypal Personality Questionnaire (DC-SPQ) based on the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders. METHODS: Under the framework of DCMs, 980 college students were recruited to calibrate item parameters of the Schizotypal Personality Questionnaire. Items that fit the psychometric characteristic would be selected to compose the DC-SPQ, prior to an analysis of its indexes. RESULTS: Results showed that the DC-SPQ had high reliability and validity in both the classical test theory and DCMs, in addition to showing a sensitivity of 0.921 and a specificity of 0.841 with area under receiver operating characteristic curve = 0.936. Meanwhile, the four-factor model proposed adequately fits with the data. More importantly, the DC-SPQ provides not only the general-level information similar to traditional questionnaires but also the symptom-level information with the posterior probability, which provides an insight into delivering the individual-specific intervention that is tailor made to schizotypal personality disorder. CONCLUSIONS: This study demonstrates that the DC-SPQ is very valuable for psychometric detection in that it can clarify the symptom being measured and provide more reasonable estimates.

Revisiting the overlap between autistic and schizotypal traits in the non-clinical population using meta-analysis and network analysis.

The present study aimed to explore the relationship between autistic and schizotypal traits in the non-clinical population. We first conducted a meta-analysis to quantify the correlation between self-reported autistic traits and the three dimensions of schizotypal traits (positive, negative and disorganization). The strongest correlation was found between autistic traits and negative schizotypal traits (r = 0.536, 95% CI [0.481, 0.586]), followed by the disorganization (r = 0.355, 95% CI [0.304, 0.404]) and positive (r = 0.256, 95% CI [0.208, 0.302]) dimensions. To visualize the partial correlations between dimensional behavioural traits, we constructed a network model based on a large sample of college students (N = 2469). Negative schizotypal traits were strongly correlated with autistic social/communicative deficits, whereas positive schizotypal traits were inversely correlated with autistic-like traits, lending support to the psychosis-autism diametrical model. Disentangling the overlapping and diametrical structure of autism and schizophrenia may help to elucidate the aetiology of these two neurodevelopmental disorders.

Differential emotional abnormalities among schizotypy clusters.

Schizotypy, a multidimensional personality organization that reflects liability to develop schizophrenia-spectrum disorders, has been associated with a number of emotional abnormalities. Yet, the exact nature of any emotional abnormalities in schizotypy is relatively unclear. Using an ethnically diverse nonclinical sample (N = 2637), the present study identified homogenous clusters of individuals based on positive and negative schizotypy dimensions and explored three interrelated domains of emotion traits closely tied to functional outcomes and quality of life: affective experience, emotional awareness, and meta-level emotions. Consistent with prior research, four schizotypy clusters were obtained: low ("nonschizotypic"), high positive, high negative, and mixed (high positive and high negative). Regarding emotion correlates of schizotypy clusters, the mixed cluster was found to be the most deviant on almost all emotion traits (e.g., heightened trait negative affect, diminished emotional clarity), suggesting that the effects of positive and negative schizotypy are additive. In addition, positive and negative schizotypy clusters were associated with differential abnormalities, with the negative cluster presenting a wider range of, and more severe, impairments compared to the low cluster (e.g., reduced trait positive affect and reduced attention to positive emotion). The current study highlights the heterogeneity in emotional traits among schizotypy dimensions and the importance of studying the mixed schizotypy in terms of emotional dysfunction.

Examining the dimensions of schizotypy from the top down: A hierarchical comparison of item-level factor solutions.

Numerous factor analytic studies of the Schizotypal Personality Questionnaire have supported a range of solutions, many with differing numbers of factors. Although some solutions have received more support than others, it remains unclear how clinicians and researchers may evaluate solutions with similar levels of empirical support in relation to one another, and few item-level analyses have been conducted. In the current study, we seek to explore the relationships among various factor solutions in a hierarchical manner using Goldberg's (2006) Bass-Ackward approach. A final sample of 847 undergraduate students completed the Schizotypal Personality Questionnaire with a Likert-style response format. Item-level exploratory factor analyses with between one and nine factors were extracted. Interrelationships among these solutions were examined. Each solution was evaluated in terms of its content, statistical significance, simple structure, and consistency with previous findings. Factor solutions at several levels were found to replicate findings from past factor analyses in terms of individual factor content and relative merit. Solutions with between four and six factors received the most support and solutions with up to seven factors were found to achieve support. (PsycINFO Database Record

Enhancing Psychosis-Spectrum Nosology Through an International Data Sharing Initiative.

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

The Network Structure of Schizotypal Personality Traits.

Elucidating schizotypal traits is important if we are to understand the various manifestations of psychosis spectrum liability and to reliably identify individuals at high risk for psychosis. The present study examined the network structures of (1) 9 schizotypal personality domains and (2) 74 individual schizotypal items, and (3) explored whether networks differed across gender and culture (North America vs China). The study was conducted in a sample of 27001 participants from 12 countries and 21 sites (M age = 22.12; SD = 6.28; 37.5% males). The Schizotypal Personality Questionnaire (SPQ) was used to assess 74 self-report items aggregated in 9 domains. We used network models to estimate conditional dependence relations among variables. In the domain-level network, schizotypal traits were strongly interconnected. Predictability (explained variance of each node) ranged from 31% (odd/magical beliefs) to 55% (constricted affect), with a mean of 43.7%. In the item-level network, variables showed relations both within and across domains, although within-domain associations were generally stronger. The average predictability of SPQ items was 27.8%. The network structures of men and women were similar (r = .74), node centrality was similar across networks (r = .90), as was connectivity (195.59 and 199.70, respectively). North American and Chinese participants networks showed lower similarity in terms of structure (r = 0.44), node centrality (r = 0.56), and connectivity (180.35 and 153.97, respectively). In sum, the present article points to the value of conceptualizing schizotypal personality as a complex system of interacting cognitive, emotional, and affective characteristics.

Perspectives on Machine Learning for Classification of Schizotypy Using fMRI Data.

Functional magnetic resonance imaging is capable of estimating functional activation and connectivity in the human brain, and lately there has been increased interest in the use of these functional modalities combined with machine learning for identification of psychiatric traits. While these methods bear great potential for early diagnosis and better understanding of disease processes, there are wide ranges of processing choices and pitfalls that may severely hamper interpretation and generalization performance unless carefully considered. In this perspective article, we aim to motivate the use of machine learning schizotypy research. To this end, we describe common data processing steps while commenting on best practices and procedures. First, we introduce the important role of schizotypy to motivate the importance of reliable classification, and summarize existing machine learning literature on schizotypy. Then, we describe procedures for extraction of features based on fMRI data, including statistical parametric mapping, parcellation, complex network analysis, and decomposition methods, as well as classification with a special focus on support vector classification and deep learning. We provide more detailed descriptions and software as supplementary material. Finally, we present current challenges in machine learning for classification of schizotypy and comment on future trends and perspectives.

Clinical trajectories in the ultra-high risk for psychosis population.

BACKGROUND: Traditionally, research in the ultra-high risk (UHR) for psychosis population has focused on the treatment of existing symptomatology and prevention of transition to psychosis. Recently, there has been an increase in focus on outcomes in individuals who do not transition to psychosis. However, there is a lack of standardised definitions of remission, recovery, recurrence and relapse in UHR, resulting in the inability to generalise and replicate outcomes. METHOD: The aims of the current study were to develop definitions for remission, recovery, recurrence and relapse, and apply them to a UHR cohort allowing the identification of longitudinal clinical trajectories. Further stratification in broader categories of favourable and unfavourable outcomes was applied. The predictive value of various baseline factors on specific clinical trajectories was also assessed. RESULTS: 17 different trajectories were identified in a cohort of 202 individuals within a 12-month period and classified according to the suggested definitions for recovery (35.7%), remission (7.5%), any recurrence (20%), no remission (17.3%), relapse (4.0%) and transition to psychosis (15.8%). Favourable and unfavourable trajectories represented 43.2% and 57.1% respectively. Long duration of untreated symptoms and high depression scores were associated with unfavourable outcomes. DISCUSSION: It is possible to apply clear definitions of remission, recovery, recurrence, relapse and transition to psychosis to a UHR cohort to evaluate longitudinal clinical trajectories. Acceptance and use of these definitions will help to facilitate comparisons between trials and to improve clinical clarity across the range of available therapeutic options in UHR individuals.

Symptom rating scales for schizophrenia and other primary psychotic disorders in ICD-11.

The subtype system for categorising presentations of schizophrenia will be removed from International Classification of Diseases 11th Revision. In its place will be a system for rating six domains of psychotic disorder pathology: positive symptoms, negative symptoms, depressive symptoms, manic symptoms, psychomotor symptoms and cognitive symptoms. This paper outlines the rationale and description of the proposed symptom rating scale, including current controversies. In particular, the scale could adopt either a 4-point severity rating or a 2-point presence/absence rating. The 4-point scale has the advantage of gathering more information, but potentially at the cost of reliability. The paper concludes by describing the field testing process for evaluating the proposed scale.

The Latent Taxonicity of Schizotypy in Biological Siblings of Probands With Schizophrenia.

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

[The concept of schizoidia in psychiatry : From schizoidia to schizotypy and cluster A personality disorders]. / Das Schizoidie-Konzept in der Psychiatrie : Von der Schizoidie über die Schizotypie zu den Cluster­A­Persönlichkeitsstörungen.

From a perspective of conceptual evolution schizoidia was initially considered to describe features both of the premorbid personality of schizophrenic patients and of the personalities of non-psychotic family members (Bleuler, Kahlbaum, Kraepelin). On a psychopatholocial level a close link to the complex basic symptom of autism was stressed. From the very beginnings of modern psychiatry schizoidia was discussed within a conceptual frame of schizophrenia spectrum disorders (Kretschmer, Hoch, Polatin). Approaches to operationalize these conceptual works laid the basis for the cluster A personalities in DSM-III. Due to the prominent concept of schizotypy (Kety, Rado, Meehl) three split up diagnostic categories of schizotypal, schizoid and paranoid personality disorders resulted. Cluster A personality disorders are frequent in community-based epidemiological studies. Health-care seeking behaviour due to primary personality-related problems, however, seems to be less paramount compared to cluster B and C personality disorders. Many family- and twin-based genetic studies convincingly stress a close link between schizotypal personality disorder and schizophrenia. This link is less pronounced for paranoid personality disorder, and even vanishingly low for schizoid personality disorder. From a perspective of schizophrenia spectrum disorders a vast amount of data from molecular genetic, neurobiological, neuropsychological and psychosocial research has impressingly confirmed this link for schizotypal personality disorder. Major research deficits, however, have to be noticed for paranoid and schizoid personality disorder.

Schizotypy-Independent and Schizotypy-Modulated Cognitive Impairments in Unaffected First-Degree Relatives of Schizophrenia-spectrum Patients.

OBJECTIVE: The aim of the study was to compare the neurocognitive profile of unaffected first-degree relatives of schizophrenia patients with control individuals, controlling for different schizotypal traits. METHOD: One hundred and fifteen adult unaffected first-degree relatives of schizophrenia-spectrum patients and 122 controls were tested for schizotypy with the Schizotypal Personality Questionnaire. They also underwent a thorough neurocognitive assessment with a range of tasks covering several aspects of executive functioning. Between-group differences in cognition were examined first with multivariate analysis of variance and then with a series of multivariate analyses of covariance, including the schizotypal dimensions as covariates. RESULTS: The relatives had higher scores on all schizotypal dimensions compared with controls and poorer planning, problem solving, strategy formation and working memory, irrespective of schizotypal traits. They also scored lower in executive working memory and verbal fluency. The difference in executive working memory was sensitive to the effects of paranoid and negative schizotypy (both dimensions abolished the between-group difference) whereas the difference in verbal fluency was sensitive only to the effects of paranoid schizotypy. Neither cognitive-perceptual nor disorganized schizotypy accounted for any differences in neurocognition between relatives and the controls. CONCLUSIONS: Impairments in planning, problem solving, strategy formation and working memory are "core" impairments in the schizophrenia-spectrum, possibly due to high heritability effects in these functions. Impairments in executive working memory and verbal fluency are associated with paranoid and negative schizotypy, possibly due to alterations in a common fronto-temporo-parietal neural network.

[Psychosis - clinical differential diagnosis]. / Differenzialdiagnose psychotischer Symptome.

BACKGROUND: Many patients with psychiatric and organic disorders may present primary or secondary psychotic symptoms. Based on the ICD 10 classification, this article describes the possible underlying diseases and their subdivision. The main focus will be differential-diagnostic evaluations of psychotic syndromes. RESULTS: In the clinical setting, the differential diagnosis of the paranoid schizophrenia and other psychotic disorders into three main disease groups is important: 1. other psychiatric diseases, 2. primary and secondary organic diseases and 3. autoimmune diseases. The first group contains, for example, drug-induced psychoses, affective disorders, personality disorders. The second group includes forms of dementia, forms of deliria or metabolic diseases. Recently, another focus is set on autoimmune diseases, especially encephalitides. SUMMARY: A detailed medical history, a physical examination and organic diagnostic can lead to the correct diagnosis and therapy. The differential-diagnostic classification and the detection of organic causes is an important part of psychiatric care, but often a good cooperation with organic specialties is needed.

Psychotic disorders in DSM-5 and ICD-11.

The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) was published by the American Psychiatric Association (APA) in 2013, and the Work Group on the Classification of Psychotic disorders (WGPD), installed by the World Health Organization (WHO), is expected to publish the new chapter about schizophrenia and other primary psychotic disorders in 2017. We reviewed the available literature to summarize the major changes, innovations, and developments of both manuals. If available and possible, we outline the theoretical background behind these changes. Due to the fact that the development of ICD-11 has not yet been completed, the details about ICD-11 are still proposals under ongoing revision. In this ongoing process, they may be revised and therefore have to be seen as proposals. DSM-5 has eliminated schizophrenia subtypes and replaced them with a dimensional approach based on symptom assessments. ICD-11 will most likely go in a similar direction, as both manuals are planned to be more harmonized, although some differences will remain in details and the conceptual orientation. Next to these modifications, ICD-11 will provide a transsectional diagnostic criterion for schizoaffective disorders and a reorganization of acute and transient psychotic and delusional disorders. In this manuscript, we will compare the 2 classification systems.

The measurement invariance of schizotypy in Europe.

The short version of the Oxford-Liverpool Inventory of Feelings and Experiences (sO-LIFE) is a widely used measure assessing schizotypy. There is limited information, however, on how sO-LIFE scores compare across different countries. The main goal of the present study is to test the measurement invariance of the sO-LIFE scores in a large sample of non-clinical adolescents and young adults from four European countries (UK, Switzerland, Italy, and Spain). The scores were obtained from validated versions of the sO-LIFE in their respective languages. The sample comprised 4190 participants (M=20.87 years; SD=3.71 years). The study of the internal structure, using confirmatory factor analysis, revealed that both three (i.e., positive schizotypy, cognitive disorganisation, and introvertive anhedonia) and four-factor (i.e., positive schizotypy, cognitive disorganisation, introvertive anhedonia, and impulsive nonconformity) models fitted the data moderately well. Multi-group confirmatory factor analysis showed that the three-factor model had partial strong measurement invariance across countries. Eight items were non-invariant across samples. Significant statistical differences in the mean scores of the s-OLIFE were found by country. Reliability scores, estimated with Ordinal alpha ranged from 0.75 to 0.87. Using the Item Response Theory framework, the sO-LIFE provides more accuracy information at the medium and high end of the latent trait. The current results show further evidence in support of the psychometric proprieties of the sO-LIFE, provide new information about the cross-cultural equivalence of schizotypy and support the use of this measure to screen for psychotic-like features and liability to psychosis in general population samples from different European countries.

[Schizophrenia or a group of endogenous diseases? The past and the present].

A critical analysis of the main concepts of schizophrenia (from the Kraepelin paradigm to the current studies attempted to «destruct¼ schizophrenia as nosologically independent disease) is presented. In author's opinion, the elimination of schizophrenia may lead to negative consequences as in aspect of clinical practice (the diagnosis of schizophrenia provides information about disease course, clinical and social outcomes) as well as in aspect of denial of autochthonous (endogenous) origin of mental disorders that fall under this definition. Based on the current level of knowledge, manifestation of these disorders can't be well explained by the adverse effects of situational, psychogenic or somatogenic factors. The restriction of the definition of schizophrenia («process¼ schizophrenia) should be brought about by the elimination of a group of schizophrenia spectrum disorders (schizotypal disorder, schizoaffective disorder, delusional psychosis).

Attenuated psychosis syndrome: a new diagnostic class?

Early detection and treatment of illness are fundamental in providing optimal health care. However, this is a major challenge in mental illness, where diagnoses depend on symptom manifestation and the symptoms are often on a continuum with behaviors observed in the non-ill population. During the past 25 years, substantial progress has been made in identifying clinical high risk for psychoses with extensive validation and the beginning of treatment trials for symptom reduction and secondary prevention of psychoses. Attenuated psychosis syndrome is placed in Section 3 of the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition, as a new disorder for further study. But the value and wisdom of creating a new disorder are hotly debated. The author advocates establishing a new disorder class as essential for progress. Key reasons to justify this view are described. Reasons to oppose the creation of a new class are briefly described.

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

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