Predictive value of thought disorder in new-onset psychosis

Formal Thought Disorders and Neurocognition in Treatment-Resistant Schizophrenia: Trouble du cours de la pensée et neurocognition dans la schizophrénie réfractaire

OBJECTIVE

Formal thought disorders (FTDs), a core feature of schizophrenia, have been subdivided into positive and negative types, and are clinically assessed by examining speech (objective) or patient introspection (subjective). Despite being associated with poorer treatment response and worse outcomes, FTDs have been understudied in patients with schizophrenia, in particular treatment-resistant schizophrenia (TRS) or schizoaffective disorder. We aimed to explore the relationship between the severity of positive and negative FTDs and neurocognition as well as social/occupational functioning in this clinical subgroup.

METHOD

This was a retrospective chart review conducted at the Clozapine Clinic at the Centre for Addiction and Mental Health, Toronto, Canada. We reviewed charted standardized assessment of FTDs using the Thought and Language Disorder (TALD) scale, neurocognition using the Brief Cognitive Assessment Tool for Schizophrenia (B-CATS), and functioning using the Social and Occupational Functioning Assessment Scale (SOFAS) between October 2022 and June 2023. Following the original factor structure of the TALD, we computed 4- factor scores that combined positive or negative and objective or subjective FTDs. We then explored the correlation between the scores from each TALD factor and the neurocognition and functioning scores.

RESULTS

We analysed data for 23 outpatients on clozapine. After the Bonferroni adjustment, total TALD scores, indicating overall severity of FTDs, were strongly and inversely correlated with SOFAS scores (p < 0.001). A strong inverse correlation was found between the objective positive TALD factor and Letter-Number Span verbal working memory scores, r(21) = -0.63, p < 0.001.

CONCLUSIONS

Our results demonstrate the strong relationship between FTDs, neurocognition, and social/occupational functioning in a sample of TRS outpatients. Within the cognitive domains assessed, verbal working memory impairment had the strongest correlation with positive FTDs, such as derailment or tangentiality. These findings highlight the value of employing standardized psychopathological scales for FTDs in clinical practice.

Computational analysis of linguistic features in speech samples of first-episode bipolar disorder and psychosis

BACKGROUND

In recent years, automated analyses using novel NLP methods have been used to investigate language abnormalities in schizophrenia. In contrast, only a few studies used automated language analyses in bipolar disorder. To our knowledge, no previous research compared automated language characteristics of first-episode psychosis (FEP) and bipolar disorder (FEBD) using NLP methods.

METHODS

Our study included 53 FEP, 40 FEBD and 50 healthy control participants who are native Turkish speakers. Speech samples of the participants in the Thematic Apperception Test (TAT) underwent automated generic and part-of-speech analyses, as well as sentence-level semantic similarity analysis based on SBERT.

RESULTS

Both FEBD and FEP were associated with the use of shorter sentences and increased sentence-level semantic similarity but less semantic alignment with the TAT pictures. FEP also demonstrated reduced verbosity and syntactic complexity. FEP differed from FEBD in reduced verbosity, decreased first-person singular pronouns, fewer conjunctions, increased semantic similarity as well as shorter sentence and word length. The mean classification accuracy was 82.45 % in FEP vs HC, 71.1 % in FEBD vs HC, and 73 % in FEP vs FEBD. After Bonferroni correction, the severity of negative symptoms in FEP was associated with reduced verbal output and increased 5th percentile of semantic similarity.

LIMITATIONS

The main limitation of this study was the cross-sectional nature.

CONCLUSION

Our findings demonstrate that both patient groups showed language abnormalities, which were more severe and widespread in FEP compared to FEBD. Our results suggest that NLP methods reveal transdiagnostic linguistic abnormalities in FEP and FEBD.

Exploring the conceptualisation, measurement, clinical utility and treatment of formal thought disorder in psychosis: A Delphi study

BACKGROUND

Formal Thought Disorder (FTD) is a recognised psychiatric symptom, yet its characterisation remains debated. This is problematic because it contributes to poor efficiency and heterogeneity in psychiatric research, with salient clinical impact.

OBJECTIVE

This study aimed to investigate expert opinion on the concept, measurement and clinical utility of FTD using the Delphi technique.

METHOD

Across three rounds, experts were queried on their definitions of FTD, methods for the assessment and measurement of FTD, associated clinical outcomes and treatment options.

RESULTS

Responses were obtained from 56 experts, demonstrating varying levels of consensus across different aspects of FTD. While consensus (>80 %) was reached for some aspects on the concept of FTD, including its definition and associated symptomology and mechanisms, others remained less clear. Overall, the universal importance attributed to the clinical understanding, measurement and treatment of FTD was clear, although consensus was infrequent as to the reasons behind and methods for doing so.

CONCLUSIONS

Our results contribute to the still elusive formal definition of FTD. The multitude of interpretations regarding these topics highlights the need for further clarity with this phenomenon. Our findings emphasised that the measurement and clinical utility of FTD are closely tied to the concept; hence, until there is agreement on the concept of FTD, difficulties with measuring and understanding its clinical usefulness to inform treatment interventions will persist. Future FTD research should focus on clarifying the factor structure and dimensionality to determine the latent structure and elucidate the core clinical phenotype.

Automated linguistic analysis in speech samples of Turkish-speaking patients with schizophrenia-spectrum disorders

Modern natural language processing (NLP) methods provide ways to objectively quantify language disturbances for potential use in diagnostic classification. We performed computerized language analysis in speech samples of 82 Turkish-speaking subjects, including 44 patients with schizophrenia spectrum disorders (SSD) and 38 healthy controls (HC). Exploratory analysis of speech samples involved 16 sentence-level semantic similarity features using SBERT (Sentence Bidirectional Encoder Representation from Text) as well as 8 generic and 8 part-of-speech (POS) features. The random forest classifier using SBERT-derived semantic similarity features achieved a mean accuracy of 85.6 % for the classification of SSD and HC. When semantic similarity features were combined with generic and POS features, the classifier's mean accuracy reached to 86.8 %. Our analysis reflected increased sentence-level semantic similarity scores in SSD. Generic and POS analyses revealed an increase in the use of verbs, proper nouns and pronouns in SSD while our results showed a decrease in the utilization of conjunctions, determiners, and both average and maximum sentence length in SSD compared to HC. Quantitative language features were correlated with the expressive deficit domain of BNSS (Brief Negative Symptom Scale) as well as with the duration of illness. These findings from Turkish-speaking interviews contribute to the growing evidence-based NLP-derived assessments in non-English-speaking patients.

A new schizophrenia screening instrument based on evaluating the patient's writing

Formal Thought Disorder (FTD) is a defining feature of schizophrenia, which is often assessed through patients' speech. Meanwhile, the written language is less studied. The aim of the present study is to establish and validate a comprehensive clinical screening scale, capturing the full variety of empirical characteristics of writing in patients with schizophrenia. The 16-item Screening Instrument for Schizophrenic Features in Writing (SISFiW) is derived from detailed literature review and a "brainstorming" discussion on 30 samples written by patients with schizophrenia. One hundred and fifty-seven participants (114 patients with an ICD-10 diagnoses of schizophrenia; 43 healthy control subjects) were interviewed and symptoms assessed with the Positive and Negative Syndrome Scale (PANSS) and the Scale for the Assessment of Thought, Language, and Communication (TLC). Article samples written by each participant were rated with the SISFiW. Results demonstrated significant difference of the SISFiW-total between the patient group and healthy controls [(3.61 ± 1.72) vs. (0.49 ± 0.63), t = 16.64, p<0.001]. The inter-rater reliability (weighted kappa = 0.72) and the internal consistency (Cronbach's alpha coefficient = 0.613) were acceptable, but correlations with the criterion (PANSS and TLC) were unremarkable. The ROC analysis indicated a cutoff point at 2 with the maximal sensitivity (93.0 %)/specificity (93.0 %). Discriminant analysis of the SISFiW items yielded 8 classifiers that discriminated between the diagnostic groups at a perfect overall performance (with 90.4 % of original and 88.5 % cross-validated grouped cases classified correctly). This instrument appears to be practicable and reliable, with relatively robust discriminatory power, and may serve as a complementary tool to existing FTD rating scales.

Evidence for the factor structure of formal thought disorder: A systematic review

Disorganised speech, or, formal thought disorder (FTD), is considered one of the core features of psychosis, yet its factor structure remains debated. This systematic review aimed to identify the core dimensions of FTD. In line with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA), a systematic review was conducted on the FTD factor analytic literature. Sixteen studies were identified from PsycINFO, PubMed and Web of Science between October 1971 and January 2023. Across the 39 factor analyses investigated, findings demonstrated the prominence of a three-factor structure. Broad agreement was found for two factors within the three-factor model, which were typically referred to as disorganisation and negative, with the exact nature of the third dimension requiring further clarification. The quality assessment revealed some methodological challenges relating to the assessment of FTD and conducted factor analyses. Future research should clarify the exact nature of the third dimension across different patient groups and methodologies to determine whether a consistent transdiagnostic concept of FTD can be elucidated.

Linguistic findings in persons with schizophrenia-a review of the current literature

INTRODUCTION

Alterations of verbalized thought occur frequently in psychotic disorders. We characterize linguistic findings in individuals with schizophrenia based on the current literature, including findings relevant for differential and early diagnosis.

METHODS

Review of literature published via PubMed search between January 2010 and May 2022.

RESULTS

A total of 143 articles were included. In persons with schizophrenia, language-related alterations can occur at all linguistic levels. Differentiating from findings in persons with affective disorders, typical symptoms in those with schizophrenia mainly include so-called "poverty of speech," reduced word and sentence production, impaired processing of complex syntax, pragmatic language deficits as well as reduced semantic verbal fluency. At the at-risk state, "poverty of content," pragmatic difficulties and reduced verbal fluency could be of predictive value.

DISCUSSION

The current results support multilevel alterations of the language system in persons with schizophrenia. Creative expressions of psychotic experiences are frequently found but are not in the focus of this review. Clinical examinations of linguistic alterations can support differential diagnostics and early detection. Computational methods (Natural Language Processing) may improve the precision of corresponding diagnostics. The relations between language-related and other symptoms can improve diagnostics.

Studying Psychosis Using Natural Language Generation: A Review of Emerging Opportunities

Disrupted language in psychotic disorders, such as schizophrenia, can manifest as false contents and formal deviations, often described as thought disorder. These features play a critical role in the social dysfunction associated with psychosis, but we continue to lack insights regarding how and why these symptoms develop. Natural language generation (NLG) is a field of computer science that focuses on generating human-like language for various applications. The theory that psychosis is related to the evolution of language in humans suggests that NLG systems that are sufficiently evolved to generate human-like language may also exhibit psychosis-like features. In this conceptual review, we propose using NLG systems that are at various stages of development as in silico tools to study linguistic features of psychosis. We argue that a program of in silico experimental research on the network architecture, function, learning rules, and training of NLG systems can help us understand better why thought disorder occurs in patients. This will allow us to gain a better understanding of the relationship between language and psychosis and potentially pave the way for new therapeutic approaches to address this vexing challenge.

Alogia and pressured speech do not fall on a continuum of speech production using objective speech technologies

Speech production is affected in a variety of serious mental illnesses (SMI; e.g., schizophrenia, unipolar depression, bipolar disorders) and at its extremes can be observed in the gross reduction of speech (e.g., alogia) or increase of speech (e.g., pressured speech). The present study evaluated whether clinically-rated alogia and pressured speech represent antithetical constructs when analyzed using objective metrics of speech production. We examined natural speech using acoustic and natural language processing features from two archival studies using several different speaking tasks and a combined 107 patients meeting criteria for SMI. Contrary to expectations, we did not find that alogia and pressured speech presented as opposing ends of a speech production continuum. Objective speech markers were associated with clinically rated alogia but not pressured speech, and these results were consistent across speaking tasks and studies. Implications for our understanding of speech production symptoms in SMI are discussed, as well as implications for Natural Language Processing and digital phenotyping efforts more generally.

Language Network Dysfunction and Formal Thought Disorder in Schizophrenia

BACKGROUND

Pathophysiological inquiries into schizophrenia require a consideration of one of its most defining features: disorganization and impoverishment in verbal behavior. This feature, often captured using the term Formal Thought Disorder (FTD), still remains to be one of the most poorly understood and understudied dimensions of schizophrenia. In particular, the large-scale network level dysfunction that contributes to FTD remains obscure to date.

STUDY DESIGN

In this narrative review, we consider the various challenges that need to be addressed for us to move towards mapping FTD (construct) to a brain network level account (circuit).

STUDY RESULTS

The construct-to-circuit mapping goal is now becoming more plausible than it ever was, given the parallel advent of brain stimulation and the tools providing objective readouts of human speech. Notwithstanding this, several challenges remain to be overcome before we can decisively map the neural basis of FTD. We highlight the need for phenotype refinement, robust experimental designs, informed analytical choices, and present plausible targets in and beyond the Language Network for brain stimulation studies in FTD.

CONCLUSIONS

Developing a therapeutically beneficial pathophysiological model of FTD is a challenging endeavor, but holds the promise of improving interpersonal communication and reducing social disability in schizophrenia. Addressing the issues raised in this review will be a decisive step in this direction.

Clinical and developmental characteristics of cognitive subgroups in a transdiagnostic sample of schizophrenia spectrum disorders and bipolar disorder

Evidence suggests that neurocognitive dysfunction is a transdiagnostic feature of individuals across the continuum between schizophrenia and bipolar disorder. However, there is significant heterogeneity of neuropsychological and social-cognitive abilities in schizophrenia, schizoaffective disorder, and bipolar disorder. The current study aimed to investigate the clinical and developmental characteristics of cognitive subgroups within the schizo-bipolar spectrum. 147 clinically stable patients with schizophrenia, schizoaffective or bipolar disorder were assessed using clinical rating scales for current psychotic and affective symptoms, and a comprehensive neuropsychological battery including measures of social cognition (Hinting and Reading the mind from the Eyes (RMET) task)). Developmental history and premorbid academic functioning were also evaluated. The study also included 36 healthy controls. Neurocognitive subgroups were investigated using latent class analysis (LCA). The optimal number of clusters was determined based on the Bayesian information criterion. A logistic regression analysis was conducted to investigate the predictors of membership to the globally impaired subgroup. LCA revealed two neurocognitive clusters including globally impaired (n = 89, 60.5%) and near-normal cognitive functioning (n = 58, 39.5%) subgroups. The near-normal cognitive functioning subgroup was not significantly different from healthy controls. The globally impaired subgroup had a higher score of developmental abnormalities (p<0.001), poorer premorbid academic functioning, mothers who were less educated and more severe disorganized speech (p = 0.001) and negative symptoms (p = 0.004) compared to the near-normal cognitive functioning group. History of developmental abnormalities and persistent disorganization rather than diagnosis are significant predictors of the subgroup of individuals with global cognitive impairment in the schizophrenia-bipolar disorder continuum.

More than words: Speech production in first-episode psychosis predicts later social and vocational functioning

Background

Several disturbances in speech are present in psychosis; however, the relationship between these disturbances during the first-episode of psychosis (FEP) and later vocational functioning is unclear. Demonstrating this relationship is critical if we expect speech and communication deficits to emerge as targets for early intervention.

Method

We analyzed three 1-min speech samples using automated speech analysis and Bayes networks in an antipsychotic-naive sample of 39 FEP patients and followed them longitudinally to determine their vocational status (engaged or not engaged in employment education or training-EET vs. NEET) after 6-12 months of treatment. Five baseline linguistic variables with prior evidence of clinical relevance (total and acausal connectives use, pronoun use, analytic thinking, and total words uttered in a limited period) were included in a Bayes network along with follow-up NEET status and Social and Occupational Functioning Assessment Scale (SOFAS) scores to determine dependencies among these variables. We also included clinical (Positive and Negative Syndrome Scale 8-item version (PANSS-8)), social (parental socioeconomic status), and cognitive features (processing speed) at the time of presentation as covariates.

Results

The Bayes network revealed that only total words spoken at the baseline assessment were directly associated with later NEET status and had an indirect association with SOFAS, with a second set of dependencies emerging among the remaining linguistic variables. The primary (speech-only) model outperformed models including parental socioeconomic status, processing speed or both as latent variables.

Conclusion

Impoverished speech, even at subclinical levels, may hold prognostic value for functional outcomes and warrant consideration when providing measurement based care for first-episode psychosis.

Disorganization domain as a putative predictor of Treatment Resistant Schizophrenia (TRS) diagnosis: A machine learning approach

BACKGROUND

Treatment Resistant Schizophrenia (TRS) is the persistence of significant symptoms despite adequate antipsychotic treatment. Although consensus guidelines are available, this condition remains often unrecognized and an average delay of 4-9 years in the initiation of clozapine, the gold standard for the pharmacological treatment of TRS, has been reported. We aimed to determine through a machine learning approach which domain of the Positive and Negative Syndrome Scale (PANSS) 5-factor model was most associated with TRS.

METHODS

In a cross-sectional design, 128 schizophrenia patients were classified as TRS (n = 58) or non-TRS (n = 60) after a structured retrospective-prospective analysis of treatment response. The random forest algorithm (RF) was trained to analyze the relationship between the presence/absence of TRS and PANSS-based psychopathological factor scores (positive, negative, disorganization, excitement, and emotional distress). As a complementary strategy to identify the variables most associated with the diagnosis of TRS, we included the variables selected by the RF algorithm in a multivariate logistic regression model.

RESULTS

according to the RF model, patients with higher disorganization, positive, and excitement symptom scores were more likely to be classified as TRS. The model showed an accuracy of 67.19%, a sensitivity of 62.07%, and a specificity of 71.43%, with an area under the curve (AUC) of 76.56%. The multivariate model including disorganization, positive, and excitement factors showed that disorganization was the only factor significantly associated with TRS. Therefore, the disorganization factor was the variable most consistently associated with the diagnosis of TRS in our sample.

The clinical relevance of formal thought disorder in the early stages of psychosis: results from the PRONIA study

BACKGROUND

Formal thought disorder (FTD) has been associated with more severe illness courses and functional deficits in patients with psychotic disorders. However, it remains unclear whether the presence of FTD characterises a specific subgroup of patients showing more prominent illness severity, neurocognitive and functional impairments. This study aimed to identify stable and generalizable FTD-subgroups of patients with recent-onset psychosis (ROP) by applying a comprehensive data-driven clustering approach and to test the validity of these subgroups by assessing associations between this FTD-related stratification, social and occupational functioning, and neurocognition.

METHODS

279 patients with ROP were recruited as part of the multi-site European PRONIA study (Personalised Prognostic Tools for Early Psychosis Management; www.pronia.eu). Five FTD-related symptoms (conceptual disorganization, poverty of content of speech, difficulty in abstract thinking, increased latency of response and poverty of speech) were assessed with Positive and Negative Symptom Scale (PANSS) and the Scale for the Assessment of Negative Symptoms (SANS).

RESULTS

The results with two patient subgroups showing different levels of FTD were the most stable and generalizable clustering solution (predicted clustering strength value = 0.86). FTD-High subgroup had lower scores in social (p_fdr < 0.001) and role (p_fdr < 0.001) functioning, as well as worse neurocognitive performance in semantic (p_fdr < 0.001) and phonological verbal fluency (p_fdr < 0.001), short-term verbal memory (p_fdr = 0.002) and abstract thinking (p_fdr = 0.010), in comparison to FTD-Low group.

CONCLUSIONS

Clustering techniques allowed us to identify patients with more pronounced FTD showing more severe deficits in functioning and neurocognition, thus suggesting that FTD may be a relevant marker of illness severity in the early psychosis pathway.

Markers of muscarinic deficit for individualized treatment in schizophrenia

Recent clinical studies have shown that agonists at muscarinic acetylcholine receptors effectively reduce schizophrenia symptoms. It is thus conceivable that, for the first time, a second substance class of procholinergic antipsychotics could become established alongside the usual antidopaminergic antipsychotics. In addition, various basic science studies suggest that there may be a subgroup of schizophrenia in which hypofunction of muscarinic acetylcholine receptors is of etiological importance. This could represent a major opportunity for individualized treatment of schizophrenia if markers can be identified that predict response to procholinergic vs. antidopaminergic interventions. In this perspective, non-response to antidopaminergic antipsychotics, specific symptom patterns like visual hallucinations and strong disorganization, the presence of antimuscarinic antibodies, ERP markers such as mismatch negativity, and radiotracers are presented as possible in vivo markers of muscarinic deficit and thus potentially of response to procholinergic therapeutics. Finally, open questions and further research steps are outlined.

Dissecting the neurobiology of linguistic disorganisation and impoverishment in schizophrenia

Schizophrenia provides a quintessential disease model of how disturbances in the molecular mechanisms of neurodevelopment lead to disruptions in the emergence of cognition. The central and often persistent feature of this illness is the disorganisation and impoverishment of language and related expressive behaviours. Though clinically more prominent, the periodic perceptual distortions characterised as psychosis are non-specific and often episodic. While several insights into psychosis have been gained based on study of the dopaminergic system, the mechanistic basis of linguistic disorganisation and impoverishment is still elusive. Key findings from cellular to systems-level studies highlight the role of ubiquitous, inhibitory processes in language production. Dysregulation of these processes at critical time periods, in key brain areas, provides a surprisingly parsimonious account of linguistic disorganisation and impoverishment in schizophrenia. This review links the notion of excitatory/inhibitory (E/I) imbalance at cortical microcircuits to the expression of language behaviour characteristic of schizophrenia, through the building blocks of neurochemistry, neurophysiology, and neurocognition.

The cognitive aspect of formal thought disorder and its relationship with global social functioning and the quality of life in schizophrenia

PURPOSE

It was expected that using a comprehensive scale like the Thought and Language Disorder Scale (TALD) for measurement of FTD would enable assessing its heterogeneity and its associations with cognitive impairment and functionality. This study has aimed to analyze the relationship between formal thought disorder (FTD) and cognitive functions, functionality, and quality of life in schizophrenia.

METHODS

This cross-sectional exploratory study included 46 clinical participants meeting the DSM-5 diagnostic criteria for schizophrenia and 35 healthy individuals as the control groups. Data were acquired by means of the Turkish language version of the TALD, the Positive and Negative Syndrome Scale, the Clinical Global Impression Scale, the Functioning Assessment Short Test, the Social Functioning Scale, the World Health Organization Quality of Life Instrument-Short Form, and a neuropsychological test battery on executive functions, working memory, verbal fluency, abstract thinking, and response inhibition. Correlation analyses were conducted to detect significant relationships.

RESULTS

The clinical group scored failures in all cognitive tests. The objective positive FTD was associated with deficits in executive functions and social functioning. The objective negative FTD was associated with poor performance in all cognitive domains, physical quality of life, and social and global functioning. The subjective negative FTD was negatively correlated with psychological quality of life.

CONCLUSION

This study demonstrated that objective FTD factors reflect different underlying cognitive deficits and correlate with different functioning domains. Significant correlation was determined between subjective negative FTD and psychological quality of life. Given the close relationship of FTD with functioning and quality of life, the FTD-related cognitive deficits should be the key treatment goal in schizophrenia.

Lower speech connectedness linked to incidence of psychosis in people at clinical high risk

BACKGROUND

Formal thought disorder is a cardinal feature of psychotic disorders, and is also evident in subtle forms before psychosis onset in individuals at clinical high-risk for psychosis (CHR-P). Assessing speech output or assessing expressive language with speech as the medium at this stage may be particularly useful in predicting later transition to psychosis.

METHOD

Speech samples were acquired through administration of the Thought and Language Index (TLI) in 24 CHR-P participants, 16 people with first-episode psychosis (FEP) and 13 healthy controls. The CHR-P individuals were then followed clinically for a mean of 7 years (s.d. = 1.5) to determine if they transitioned to psychosis. Non-semantic speech graph analysis was used to assess the connectedness of transcribed speech in all groups.

RESULTS

Speech was significantly more disconnected in the FEP group than in both healthy controls (p < .01) and the CHR-P group (p < .05). Results remained significant when IQ was included as a covariate. Significant correlations were found between speech connectedness measures and scores on the TLI, a manual assessment of formal thought disorder. In the CHR-P group, lower scores on two measures of speech connectedness were associated with subsequent transition to psychosis (8 transitions, 16 non-transitions; p < .05).

CONCLUSION

These findings support the utility and validity of speech graph analysis methods in characterizing speech connectedness in the early phases of psychosis. This approach has the potential to be developed into an automated, objective and time-efficient way of stratifying individuals at CHR-P according to level of psychosis risk.

Understanding Language Abnormalities and Associated Clinical Markers in Psychosis: The Promise of Computational Methods

The language and speech of individuals with psychosis reflect their impairments in cognition and motor processes. These language disturbances can be used to identify individuals with and at high risk for psychosis, as well as help track and predict symptom progression, allowing for early intervention and improved outcomes. However, current methods of language assessment-manual annotations and/or clinical rating scales-are time intensive, expensive, subject to bias, and difficult to administer on a wide scale, limiting this area from reaching its full potential. Computational methods that can automatically perform linguistic analysis have started to be applied to this problem and could drastically improve our ability to use linguistic information clinically. In this article, we first review how these automated, computational methods work and how they have been applied to the field of psychosis. We show that across domains, these methods have captured differences between individuals with psychosis and healthy controls and can classify individuals with high accuracies, demonstrating the promise of these methods. We then consider the obstacles that need to be overcome before these methods can play a significant role in the clinical process and provide suggestions for how the field should address them. In particular, while much of the work thus far has focused on demonstrating the successes of these methods, we argue that a better understanding of when and why these models fail will be crucial toward ensuring these methods reach their potential in the field of psychosis.

Examining Self-Reported Thought Disorder: Continuous Variation, Convergence with Schizotypy, and Cognitive Correlates

When measured from the perspective of a clinician, the severity of 'objective' thought disorder (TD) has been found to vary continuously between people with and without psychosis-related diagnoses, and has been linked with semantic and executive dysfunctions in people with psychosis. Measures of 'subjective' TD that are derived from a first-person perspective have also been produced, but their relationships with objective TD and cognition are unclear. The aims of the current study were: to determine whether responses on a self-report TD questionnaire correspond with responses to a self-report measure of schizotypal disorganization; and to explore the association between these self-reported subjective TD severities and cognitive performance. Data was collected from a sample of 33 people without psychiatric diagnoses and 38 people diagnosed with schizophrenia or schizoaffective disorder evincing mild symptomatology, and this data was pooled for analysis in accordance with the continuum model. Self-reported TD frequencies were associated with the endorsement of disorganized schizotypal experiences. Moreover, self-reported TD frequencies showed relationships with measures of semantic and executive functioning. Thus, at mild severities, self-reported TD shows continuous variation and is associated with altered cognitive function.

Is cognitive behavioural therapy effective for individuals experiencing thought disorder?

Various clinical guidelines recommend cognitive behavioural therapy (CBT) to treat psychosis without reference to patients' thought disorder. However, there is a risk that disorganized thinking hampers CBT. We tested the prediction that thought disorder would interfere with the effectiveness of CBT for hallucinations and delusions, compared to treatment as usual and supportive counselling, in secondary data from two large, single blind randomised controlled trials. We fitted latent growth curve models separately for the development of frequency and distress of symptoms. CBT was significantly more successful than counselling in reducing delusional frequency in the short term and hallucinatory distress at any point, even in those with relatively high thought disorder. We found little evidence that clinicians should restrict CBT in this subgroup of patients. Nevertheless, the findings highlight the importance of effective initial treatment of thought disorder in maximising the benefit of CBT for psychosis, particularly for reducing distress from hallucinations.

The Complex Relationship Among Formal Thought Disorders, Neurocognition, and Functioning in Nonacutely Ill Schizophrenia Patients

The aims of the present study were to 1) evaluate clinical differences between patients suffering from schizophrenia (SZ) with mild versus moderate/severe formal thought disorder (FTD); 2) explore relationships between dimensions of FTD, neuropsychological domains, and global functioning; and 3) compare clinical dimensions of FTD in early and late SZ. One hundred thirty-six individuals with schizophrenia were recruited and evaluated during a nonacute phase of illness. FTD was assessed with the Thought, Language, and Communication Scale. Partial correlations, t-tests, and stepwise regression were undertaken to address the study aims. Patients with moderate/severe FTD performed worse than those with mild FTD for processing speed, reasoning and problem solving, and social cognition, and demonstrated poorer global functioning. Early SZ did not differ from late SZ in terms of negative FTD and difficulty in abstract thinking (DAT). Negative FTD was correlated with reasoning and problem solving; DAT was correlated with social cognition. All clinical dimensions of FTD, regardless of neurocognitive impairment, accounted for a significant amount of variance in global functioning. FTD predicted global functioning, regardless of neurocognitive factors. Due to their stability in different phases of the course of the disease and their strong relationship with other core variables, Neg-FTD and DAT should be investigated as an intermediate phenotype of the illness.

Altered syntactic abilities in first episode patients: An inner phenomenon characterizing psychosis

BACKGROUND

Research has consistently shown that language abilities represent a core dimension of psychosis; however, to date, very little is known about syntactic comprehension performance in the early stages of psychosis. This study aims to compare the linguistic abilities involved in syntactic comprehension in a large group of First Episode Psychosis (FEP) patients and healthy controls (HCs).

METHODS

A multiple choice test of comprehension of syntax was administered to 218 FEP patients (166 non-affective FEP patients [FEP-NA] and 52 affective FEP patients [FEP-A]) and 106 HCs. All participants were asked to match a sentence they listen with one out of four vignettes on a pc screen. Only one vignette represents the stimulus target, while the others are grammatical or non-grammatical (visual) distractors. Both grammatical and non-grammatical errors and performance in different syntactic constructions were considered.

RESULTS

FEP committed greater number of errors in the majority of TCGB language domains compared to HCs. Moreover, FEP-NA patients committed significantly more non-grammatical (z = -3.2, p = 0.007), locative (z = -4.7, p < 0.001), passive-negative (z = -3.2, p = 0.02), and relative (z = -4.6, p < 0.001) errors compared to HCs as well as more passive-affirmative errors compared to both HCs (z = -4.3, p < 0.001) and FEP-A (z = 3.1, p = 0.04). Finally, we also found that both FEP-NA and FEP-A committed more grammatical (FEP-NA: z = -9.2, p < 0.001 and FEP-A: z = -4.4, p < 0.001), total (FEP-NA: z = -8.2, p < 0.001 and FEP-A: z = 3.9, p =  0.002), and active-negative (FEP-NA: z = -5.8, p < 0.001 and FEP-A: z = -3.5, p = 0.01) errors compared to HCs.

CONCLUSIONS

This study shows that the access to syntactic structures is already impaired in FEP patients, especially in those with FEP-NA, ultimately suggesting that language impairments represent a core and inner feature of psychosis even at early stages.

Examination of formal thought disorder and its clinical correlates with the Turkish Version of the Thought and Language Disorder Scale (TALD-TR) in schizophrenia

BACKGROUND

Formal thought disorder (FTD) is considered to be a fundamental feature of schizophrenia. This study aims to analyze psychometric properties of the Turkish version of "Thought and Language Disorder Scale (TALD)" and investigate the relationship between FTD and various clinical characteristics in patients with schizophrenia.

METHODS

TALD was adapted into Turkish and applied to a total of 149 participants of which 114 had DSM-5 psychiatric diagnoses (schizophrenia N = 70, mania N = 20, depression N = 24) and 35 were healthy controls. Positive and Negative Syndrome Scale (PANSS), Hamilton Depression Rating Scale, Young Mania Rating Scale, and Clinical Global Impression were administered to detect illness severity.

RESULTS

The principal component analyses revealed that the Turkish version of TALD (TALD-TR) consisted of four factors including the Objective Positive (OP), Subjective Negative (SN), Objective Negative (ON) and Subjective Positive (SP) symptom dimensions which were in line with the original TALD factorial structure. It was concluded that TALD-TR shows strong construct validity and high interrater reliability. The correlation analyses with TALD-TR and PANSS showed that there are positive correlations between the TALD-TR total score and the PANSS total and subscale scores. Each diagnostic group showed the distinct pattern of FTD. The mania group exhibited the highest mean total score in the OP, whereas the schizophrenia group exhibited the highest mean total score in the ON factor. In the schizophrenia group, the severity of FTD correlated positively with duration of illness and negatively with age at onset of illness.

CONCLUSION

Adaptation of TALD into different languages seems to be possible, bringing in an international tool for research on FTD.

Neurocognitive and linguistic correlates of positive and negative formal thought disorder: A meta-analysis

Executive dysfunction and language impairment are the most prominent neuropsychological models of formal thought disorder (FTD) in schizophrenia. However, available studies have provided contradictory findings regarding the accuracy of these models. Furthermore, specific neurocognitive underpinnings of positive FTD (PosFTD) and negative FTD (NegFTD) are not clear. Following the systematic review of schizophrenia studies, a random-effects meta-analysis of the relationship between FTD and neurocognition/language in schizophrenia was conducted in 52 reports including 2805 patients. Neurocognition was significantly associated with both PosFTD (r = -0.21, CI = -0.14 to -0.27) and NegFTD (r = -0.24, CI = -0.18 to -0.30). Both PosFTD (r = ranged from -0.18 to -0.27) and NegFTD (r = ranged from -0.19 to -0.23) were significantly correlated with verbal memory, visual memory, attention, and processing speed. In meta-analyses of executive functions, PosFTD was significantly associated with working memory (r = -0.21), planning (r = -0.19), and inhibition (r = -0.21) and NegFTD was significantly associated with planning (r = -0.27), fluency (r = -0.27), and working memory (r = -0.24). In meta-analyses of linguistic variables, PosFTD was associated with deficits in syntactic comprehension (r = -0.27) and semantic processing (r = -0.18). In contrast, NegFTD was associated only with semantic comprehension (r = -0.21). Both PosFTD and NegFTD were significantly associated with executive dysfunction, neurocognitive deficits and semantic dysfunction but syntactic deficits were more specific to PosFTD. There were also some distinct patterns of relationships between the pattern of executive dysfunction and types of FTD. Fluency deficit was associated more strongly with NegFTD and poor inhibition was more specifically related to PosFTD. Current findings suggest that neurocognitive and linguistic correlates of PosFTD and NegFTD might be partly different.

A machine learning approach to predicting psychosis using semantic density and latent content analysis

Subtle features in people’s everyday language may harbor the signs of future mental illness. Machine learning offers an approach for the rapid and accurate extraction of these signs. Here we investigate two potential linguistic indicators of psychosis in 40 participants of the North American Prodrome Longitudinal Study. We demonstrate how the linguistic marker of semantic density can be obtained using the mathematical method of vector unpacking, a technique that decomposes the meaning of a sentence into its core ideas. We also demonstrate how the latent semantic content of an individual’s speech can be extracted by contrasting it with the contents of conversations generated on social media, here 30,000 contributors to Reddit. The results revealed that conversion to psychosis is signaled by low semantic density and talk about voices and sounds. When combined, these two variables were able to predict the conversion with 93% accuracy in the training and 90% accuracy in the holdout datasets. The results point to a larger project in which automated analyses of language are used to forecast a broad range of mental disorders well in advance of their emergence.

A systematic review of task-based functional neuroimaging studies investigating language, semantic and executive processes in thought disorder

The aim of the current systematic review was to synthesise the research that has investigated thought disorder (TD) using task-based functional neuroimaging techniques to target executive, language, or semantic functions. Thirty-five pertinent studies were identified from January 1990 to August 2016. Functional correlates of TD included the superior and middle temporal, fusiform, and inferior frontal gyri bilaterally, as well as the left and right cingulate cortex, the right caudate nucleus, and the cerebellum. TD-related increases and decreases in activation were both evident in most of these regions. However, the specificity of these correlates from general clinical and cognitive influences is unknown. The cortical regions implicated overlap with those thought to contribute to language and semantic systems. Cortico-striatal circuitry may also play a role in some aspects of TD through aberrant salience representation and inappropriate attentional prioritisation. To advance the field further, greater integration across structural, functional, and behavioural measures is required, in addition to non-unitary considerations of TD.

To use the brief psychiatric rating scale to detect disorganized speech in schizophrenia: Findings from the REAP-AP study

Our study aimed to assess the psychometric validity of the conceptual disorganization item and other items of the Brief Psychiatric Rating Scale (BPRS) for detecting disorganized speech in patients with schizophrenia. We included 357 schizophrenia patients with disorganized speech and 1082 without disorganized speech from the survey centers in India, Indonesia, Japan, Malaysia, and Taiwan, using the data from the Research on Asian Psychotropic Patterns for Antipsychotics (REAP-AP) study. After adjusting the effects of confounding variables, a binary logistic regression model was fitted to identify BPRS items independently associated with disorganized speech. Receiver operating characteristic (ROC) curves were used to identify optimum cut-off scores and their sensitivities and specificities for detecting disorganized speech. After adjusting the effects of confounding variables, the fitted binary logistic regression model indicated that conceptual disorganization (P < 0.0001), uncooperativeness (P = 0.010) and excitement (P = 0.001) were independently associated with disorganized speech. The ROC curve revealed that the conceptual disorganization item could accurately detect disorganized speech in patients with schizophrenia both separately and in combination with uncooperativeness and excitement. The subscale for conceptual disorganization, uncooperativeness and excitement items in the BPRS is a promising psychometric tool for detecting disorganized speech.

Resting state perfusion in the language network is linked to formal thought disorder and poor functional outcome in schizophrenia

OBJECTIVE

Formal thought disorder (FTD) is a core symptom in schizophrenia. Here, we focus on resting state cerebral blood flow (rCBF) linked to dimensions of FTD.

METHODS

We included 47 schizophrenia spectrum patients and 30 age- and gender-matched healthy controls. We assessed FTD with the assessment of thought, language, and communication (TLC) and imaging on a 3T MRI scanner. Within patients, we tested the association of FTD dimensions and in a subgroup (n = 27) the association of functional outcome after 6 months with whole brain rCBF.

RESULTS

Negative FTD was most prominently associated with perfusion within the superior temporal gyrus, while positive FTD was associated with perfusion within the supplementary motor area, and inferior frontal gyrus. Perfusion within the left supramarginal gyrus was associated with social functioning after 6 months.

CONCLUSIONS

Distinguishable associations of rCBF with FTD dimensions point to distinct underlying pathophysiology. The location of aberrant perfusion patterns suggests that negative FTD might reflect defective access to semantic memory while positive FTD likely reflects defective suppression of irrelevant information during increased speech production. Finally, the neural correlates of thought block were also predictive of poor functional outcome. Thus, functional outcome and distinct FTD dimensions may share some pathophysiology.

Individual negative symptoms and domains - Relevance for assessment, pathomechanisms and treatment

The negative symptoms of schizophrenia can be divided into two domains. Avolition/apathy includes the individual symptoms of avolition, asociality and anhedonia. Diminished expression includes blunted affect and alogia. Until now, causes and treatment of negative symptoms have remained a major challenge, which is partially related to the focus on negative symptoms as a broad entity. Here, we propose that negative symptoms may become more tractable when the different domains and individual symptoms are taken into account. There is now increasing evidence that the relationship with clinical variables - in particular outcome - differs between the domains of avolition/apathy and diminished expression. Regarding models of negative symptom formation, those relevant to avolition/apathy are now converging on processes underlying goal-directed behavior and dysfunctions of the reward system. In contrast, models of the diminished expression domains are only beginning to emerge. The aim of this article is to review the specific clinical, behavioral and neural correlates of individual symptoms and domains as a better understanding of these areas may facilitate specific treatment approaches.

Formal thought disorder in schizophrenia and bipolar disorder: A systematic review and meta-analysis

Historically, formal thought disorder has been considered as one of the distinctive symptoms of schizophrenia. However, research in last few decades suggested that there is a considerable clinical and neurobiological overlap between schizophrenia and bipolar disorder (BP). We conducted a meta-analysis of studies comparing positive (PTD) and negative formal thought disorder (NTD) in schizophrenia and BP. We included 19 studies comparing 715 schizophrenia and 474 BP patients. In the acute inpatient samples, there was no significant difference in the severity of PTD (d=-0.07, CI=-0.22-0.09) between schizophrenia and BP. In stable patients, schizophrenia was associated with increased PTD compared to BP (d=1.02, CI=0.35-1.70). NTD was significantly more severe (d=0.80, CI=0.52-0.1.08) in schizophrenia compared to BP. Our findings suggest that PTD is a shared feature of both schizophrenia and BP but persistent PTD or NTD can distinguish subgroups of schizophrenia from BP and schizophrenia patients with better clinical outcomes.

The prognostic value of formal thought disorder following first episode psychosis

BACKGROUND

Formal thought disorder (FTD) is associated with poor outcome in established psychotic illnesses and it can be assessed as a categorical or dimensional variable. However, its influence on functional outcome and hospitalisation patterns in early psychosis has not been investigated. We evaluated the relationship between FTD and these outcomes in a first episode psychosis (FEP) sample.

MATERIALS AND METHODS

A mixed diagnostic FEP cohort was recruited through an Early Intervention in Psychosis Service in Ireland. Participants were assessed at initial presentation and one year later with the MIRECC GAF to evaluate social and occupational functioning domains. Disorganisation (disFTD), verbosity (verFTD) and poverty (povFTD) dimensions of FTD were examined at both time points, as well as a unitary FTD construct. Analyses were controlled for demographic, clinical and treatment variables.

RESULTS

DisFTD was the only FTD dimension associated with functional outcome, specifically social functioning, on multivariate analysis (beta=0.13, P<0.05). The unitary FTD construct was not associated with functional outcome. DisFTD at FEP presentation predicted a greater number of hospitalisations (adjusted beta=0.24, P<0.001) and prolonged inpatient admission (adjusted OR=1.08, 95% CI 1.02-1.15, P<0.05) following FEP.

CONCLUSIONS

Longitudinal and dimensional evaluation of FTD has a clinical utility that is distinct from a cross-sectional or unitary assessment. Dimensions of FTD may map onto different domains of functioning. These findings are supportive of some of the changes in DSM-V with an emphasis on longitudinal and dimensional appraisal of psychopathology. Communication disorders may be considered a potential target for intervention in psychotic disorders.

Formal thought disorder in first-episode psychosis

Formal thought disorder (FTD) is one of the fundamental symptom clusters of schizophrenia and it was found to be the strongest predictor determining conversion from first-episode acute transient psychotic disorder to schizophrenia. Our goal in the present study was to compare a first-episode psychosis (FEP) sample to a healthy control group in relation to subtypes of FTD. Fifty six patients aged between 15 and 45years with FEP and forty five control subjects were included in the study. All the patients were under medication for less than six weeks or drug-naive. FTD was assessed using the Thought and Language Index (TLI), which is composed of impoverishment of thought and disorganization of thought subscales. FEP patients showed significantly higher scores on the items of poverty of speech, weakening of goal, perseveration, looseness, peculiar word use, peculiar sentence construction and peculiar logic compared to controls. Poverty of speech, perseveration and peculiar word use were the significant factors differentiating FEP patients from controls when controlling for years of education, family history of psychosis and drug abuse.

The impact of thought disorder on therapeutic alliance and personal recovery in schizophrenia and schizoaffective disorder: An exploratory study

Thought and language disorders are a main feature of schizophrenia. The aim of the study is to explore the impact of thought disorder on therapeutic alliance and personal recovery because of its interference with verbal communication. Thought disorder, positive and negative symptoms (Positive and Negative Syndrome Scale), functioning (Modified Global Assessment of Functioning scale), insight (Scale to Assess Unawareness of Mental Disorder), attachment insecurity (Psychosis Attachment Measure), therapeutic alliance (Scale to Assess the Therapeutic Relationship), and personal recovery (Recovery Assessment Scale, Integration Sealing-Over Scale) were assessed in 133 outpatients with schizophrenia or schizoaffective disorder at baseline and twelve months later. The data were analyzed by hierarchical multiple linear regression. Higher levels of thought disorder were significantly associated with lower clinicians' ratings, but not with patients' ratings of therapeutic alliance. In addition, lower clinicians' ratings of therapeutic alliance were significantly linked to a more sealing over and less integrative recovery style. In fact, the lower therapeutic alliance ratings mediated the association between thought disorder and a sealing over recovery style. The results highlight the importance of considering thought disorder in treatment of schizophrenia and schizoaffective disorder which may interfere with therapeutic alliance and treatment efforts towards recovery.

Language disturbance and functioning in first episode psychosis

Language disturbance has a central role in the presentation of psychotic disorders however its relationship with functioning requires further clarification, particularly in first episode psychosis (FEP). Both language disturbance and functioning can be evaluated with clinician-rated and performance-based measures. We aimed to investigate the concurrent association between clinician-rated and performance-based measures of language disturbance and functioning in FEP. We assessed 108 individuals presenting to an Early Intervention in Psychosis Service in Ireland. Formal thought disorder (FTD) dimensions and bizarre idiosyncratic thinking (BIT) were rated with structured assessment tools. Functioning was evaluated with a performance-based instrument, a clinician-rated measure and indicators of real-world functioning. The disorganisation dimension of FTD was significantly associated with clinician-rated measures of occupational and social functioning (Beta=-0.19, P<0.05 and Beta=-0.31, P<0.01, respectively). BIT was significantly associated with the performance-based measure of functioning (Beta=-0.22, P<0.05). Language disturbance was of less value in predicting real-world measures of functioning. Clinician-rated and performance-based assessments of language disturbance are complementary and each has differential associations with functioning. Communication disorders should be considered as a potential target for intervention in FEP, although further evaluation of the longitudinal relationship between language disturbance and functioning should be undertaken.

Early-Onset Schizophrenia: Exploring the Contribution of the Thought Disorder Index to Clinical Assessment

Background:

Differentiating diagnostically between schizophrenia and emotional and personality disorders with psychotic or psychotic-like symptoms is a challenging task. It is especially difficult when working with adolescent patients, because their symptoms tend to manifest at lower levels as compared with adult patients. Thought disorder is a core symptom of schizophrenia, and the Rorschach Inkblot Method is widely used for the assessment of formal thought disorder.

Objective:

In this study, which is situated within ongoing clinical practice, we investigated whether the Rorschach test is helpful for assessing early-onset schizophrenia due to its ability to detect thought disorder. We also wanted to examine whether the Thought Disorder Index (TDI) is superior to the Comprehensive System (CS) for differentiating between patients with early-onset schizophrenia and non-psychotic patients experiencing auditory and visual hallucinations. An additional aim was to examine whether the TDI correlated with the Positive and Negative Syndrome Scale (PANSS).

Methods:

Twenty-three subjects between the ages of 12 and 18 years were examined with the use of the Rorschach test, and the protocols were scored according to both the TDI and the CS. All subjects were also assessed with the Positive and Negative Syndrome Scale. The sample included 14 subjects who fulfilled the criteria for schizophrenia and 9 subjects who were experiencing hallucinations that emanated from severe emotional and relational problems but who had different non-psychotic disorders.

Results:

Although the two groups could not be distinguished with regard to their total scores for thought disorder, the identification of specific thought disorder types proved useful for differential diagnosis. Verbalizations that were categorized by the TDI as “absurd responses,” “fluidity,” “contamination,” “autistic logic,” and “word-finding difficulty” were only given by patients who had been diagnosed with schizophrenia. When patients’ responses were scored with the use of the CS, the “contamination” score was the only one found to be specific to schizophrenia.

Conclusions:

Although the sample size limits the conclusions that can be drawn, the results indicate that the TDI may be superior to the CS for the identification of thought disorder specific to—but not always present in—adolescents with schizophrenia. In other words, the absence of severe thought disorder is not synonymous with the absence of severe psychopathology, but the presence of the most severe thought disorder types (i.e., “absurd responses,” “fluidity,” “incoherence,” “contamination,” and “autistic logic”) seems to be a strong indicator of schizophrenic psychopathology.

Haemodynamic and electrophysiological markers of pragmatic language comprehension in schizophrenia

OBJECTIVES

The present study aimed at investigating neurophysiological markers of language perception in schizophrenia using simultaneous near-infrared spectroscopy (NIRS) and event-related potentials (ERPs), which have been proven to be useful for studying language processing abilities in psychiatric patients. The study shall help to integrate previous findings from ERP and fMRI studies on figurative language comprehension in schizophrenia and elucidate how electrophysiological and haemodynamic markers of language processing are related.

METHODS

Twenty-two healthy subjects and 22 schizophrenia patients judged 120 sentences regarding their meaningfulness. Phrases were literal, metaphoric, or meaningless. EEG-fNIRS signals were recorded throughout the entire experiment.

RESULTS

Schizophrenia patients showed deficient and delayed sentence comprehension. Both the early N400 and left-hemispheric activation during language comprehension were altered in patients. Correlation analyses showed that metaphor-related ERPs were strongly linked to haemodynamic cortical activity in healthy subjects, but not in patients.

CONCLUSIONS

Our results indicate group differences in cortical electrophysiological and haemodynamic activation that represent rather general impairments in the processing of complex language. Simultaneous EEG/NIRS applications are useful to depict these neural markers and to investigate their relationship. Future studies are needed to clarify the nature of respective anomalies and their potential as putative neural markers in schizophrenia research.

The Epidemiology and Associated Phenomenology of Formal Thought Disorder: A Systematic Review

BACKGROUND

Authors of the Diagnostic and Statistical Manual, Fifth Edition (DSM-V) have recommended to "integrate dimensions into clinical practice." The epidemiology and associated phenomenology of formal thought disorder (FTD) have been described but not reviewed. We aimed to carry out a systematic review of FTD to this end.

METHODS

A systematic review of FTD literature, from 1978 to 2013, using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

A total of 881 abstracts were reviewed and 120 articles met inclusion criteria; articles describing FTD factor structure (n = 15), prevalence and longitudinal course (n = 41), role in diagnosis (n = 22), associated clinical variables (n = 56), and influence on outcome (n = 35) were included. Prevalence estimates for FTD in psychosis range from 5% to 91%. Dividing FTD into domains, by factor analysis, can accurately identify 91% of psychotic diagnoses. FTD is associated with increased clinical severity. Poorer outcomes are predicted by negative thought disorder, more so than the typical construct of "disorganized speech."

CONCLUSION

FTD is a common symptom of psychosis and may be considered a marker of illness severity. Detailed dimensional assessment of FTD can clarify diagnosis and may help predict prognosis.

Prognostic implications of paranoia and thought disorder in new onset psychosis

This study follows a group of 174 young people with new onset of schizotypal symptoms and examines factors which may lead to conversion to psychosis. These prodromal subjects were screened for symptoms and later given the Structured Clinical Interview of DSM-III-R at one year, two years and ten years post onset. We also included the Paranoia Scale of Fenigstein and Vanable and the Scale for Thought, Language and Communications of Andreasen in all interviews. Our analysis found that the addition of scales for paranoia and thought disorder enhanced prediction of conversion to psychosis and long term outcome. The early occurrence of ideas of reference and poverty of thought appear to be significant predictors of future deterioration even when considered among other high-risk variables.

Building a neurocognitive profile of thought disorder in schizophrenia using a standardized test battery

A core symptom of schizophrenia is thought disorder (TD). The cognitive abilities of semantic processing and executive function are argued to be etiologically linked to TD. However, there has been no comprehensive investigation of neurocognition in TD to date. The neurocognitive profile of 58 schizophrenia patients and 48 healthy controls was examined using the MATRICS Consensus Cognitive Battery and the D-KEFS Color-Word Interference Test. TD patients performed more poorly than non-TD patients on the cognitive domains of Verbal Learning and Inhibition, reflective of semantic and executive function respectively, confirming their critical roles over and above other cognitive deficits in schizophrenia.

Functional MRI of sentence-level language comprehension in schizophrenia: a coordinate-based analysis

Numerous authors have hypothesised that abnormal pathways for language play a key role in the pathophysiology of schizophrenia, a notion that is supported by structural imaging and post-mortem findings especially in patients with thought disorder and auditory verbal hallucinations. Recently, an increasing number of functional magnetic resonance imaging (fMRI) investigations addressed language comprehension schizophrenia. We present a systematic review of the fMRI-studies on sentence- and text-level language comprehension in schizophrenia. 13 studies met the inclusion criteria. Additional studies specifically addressed language lateralization. Coordinates for differential contrasts for healthy controls>patients reported in these studies indicate that the left fronto-temporal language network is altered in schizophrenia. 33 out of the 51 reported coordinates are located in the left hemisphere. Overactivation in schizophrenia extends into premotor areas and is about equally divided among the left and right hemispheres. Several negative studies indicate heterogeneity within schizophrenia, which could possibly be related to the severity of thought disorder or auditory verbal hallucinations of patients. Activation changes related to thought disorder within schizophrenia (n=4 studies) include the inferior frontal and superior temporal gyri and are moderately lateralized to the left hemisphere. Although current fMRI literature is still insufficient to draw decisive conclusions, results point towards functionally altered pathways for language in schizophrenia. This notion is also plausible from the viewpoint of psychopathology especially since hallmark symptoms of the disease, thought disorder, auditory verbal hallucinations and alogia, are expressed in terms of language or represent abnormalities of language function.