Measuring thought disorder with clinical rating scales in schizophrenic and nonschizophrenic patients

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.

Assessing the dimensionality of scores derived from the Revised Formal Thought Disorder Self-Report Scale in schizotypy

The current work explored the dimensionality and convergent validity of responses to Barrera et al.'s (2015) 29-item Formal Thought Disorder-Self Scale (FTD-SS) obtained in two non-clinical samples. Exploratory factor analyses were conducted in Sample 1 (n = 324), yielding evidence of three correlated factors, although simple structure was not achieved until nine items were removed. Support for the correlated three factors model of responses to the revised 20-item scale (FTD-SS-R) was replicated when a confirmatory factor analysis was conducted in Sample 2 (n = 610). Finally, convergent associations were found between FTD-SS-R scores and scores from other schizotypy measures across both samples, though these measures only explained half of the variance in FTD-SS-R scores. Additional research is needed to evaluate the appropriateness of the items and incremental validity of the scale in non-clinical samples.

Schizophrenia phenomenology revisited: positive and negative symptoms are strongly related reflective manifestations of an underlying single trait indicating overall severity of schizophrenia

BACKGROUND

To examine whether negative symptoms, psychosis, hostility, excitation, and mannerism (PHEM symptoms), formal thought disorders (FTD) and psychomotor retardation (PMR) are interrelated phenomena in major neurocognitive psychosis (MNP) or deficit schizophrenia and whether those domains belong to an underlying latent vector reflecting general psychopathology.

METHODS

In this study, we recruited 120 patients with MNP or deficit schizophrenia and 54 healthy subjects and measured the above-mentioned symptom domains.

RESULTS

In MNP, there were significant associations between negative and PHEM symptoms, FTD and PMR. A single latent trait, which is essentially unidimensional, underlies these key domains of schizophrenia and MNP and additionally shows excellent internal consistency reliability, convergent validity, and predictive relevance. Confirmatory Tedrad Analysis indicates that this latent vector fits a reflective model. The lack of discriminant validity shows that positive (and PHEM or psychotic) and negative symptoms greatly overlap and probably measure the same latent construct. Soft independent modeling of class analogy (SIMCA) shows that MNP (diagnosis based on negative symptoms) is better modeled using PHEM symptoms, FTD, and PMR than negative symptoms.

CONCLUSIONS

In stable phase MNP, which is a restricted sample of the schizophrenia population, negative and PHEM symptoms, FTD and PMR belong to one underlying latent vector reflecting overall severity of schizophrenia (OSOS). The bi-dimensional concept of "positive" and "negative" symptoms cannot be validated and, therefore, future research in stable phase schizophrenia should consider that the latent phenomenon OSOS as well as its reflective manifestations are the key factors of schizophrenia phenomenology.

Rationale for BPRS use in routine clinical practice: quantitative assessment of psychopathology, consistent with clinical sense

The Brief Psychiatric Rating Scale (BPRS) is expected to provide a valuable instrument for routine evaluation of the patient's status and correct interpretation of concentrations measured during therapeutic monitoring of antipsychotic drugs. Inpatient files were searched for information relative to acute episodes and BPRS items were scored every 10 days until discharge from the hospital according to a retrospective scheme. Eighty patients were included, who met DSM III criteria for schizophrenia and bipolar disorder. Clusters of symptoms that tend to appear together were identified through principal components analysis and are in keeping with factors described previously. Differences with respect to diagnosis further suggest that such clusters convey clinically relevant information. The time course of haloperidol action was also investigated: an average 51 % improvement was observed over the first 10 days, while the proportion of patients showing a 50% or larger BPRS decrease at the time of discharge reached 90%. The prominent contribution of changes in positive, florid symptoms to global improvement is also described. Finally, association of clinical improvement with a shorter period of hospitalization is shown. These results indicate that the BPRS represents a level of abstraction compatible with the way clinicians communicate and that its introduction into routine practice may allow for better description of the course of illness

Eotaxin, an Endogenous Cognitive Deteriorating Chemokine (ECDC), Is a Major Contributor to Cognitive Decline in Normal People and to Executive, Memory, and Sustained Attention Deficits, Formal Thought Disorders, and Psychopathology in Schizophrenia Patients

Eotaxin is increased in neurodegenerative disorders and schizophrenia, and preclinical studies indicate that eotaxin may induce cognitive deficits. This study aims to examine whether peripheral levels of eotaxin impact cognitive functioning in healthy volunteers and formal thought disorder (FTD) and psychopathology in schizophrenia patients. Serum levels of eotaxin were assayed and cognitive tests were performed on a sample of 40 healthy participants and 80 schizophrenia patients. Among healthy participants, eotaxin levels were significantly associated with episodic/semantic memory, executive functions, Mini Mental State Examination, emotion recognition, and sustained attention. In addition, age-related effects on these cognitive measures were partly mediated by eotaxin. The super-variable "age-eotaxin" predicted a large part of the variance in cognitive functions among healthy participants, and hence, eotaxin may act as an "accelerated brain aging chemokine" (ABAC). In schizophrenia, eotaxin levels had a strong impact on formal thought disorders and psychopathology. In schizophrenia, increased eotaxin strongly impacts memory and sustained attention, which together to a large extent determine FTD. FTD together with memory deficits predicts around 92.5% of the variance in psychopathology. Moreover, the effects of eotaxin are partially mediated by executive functioning, while the effects of male sex on FTD and psychopathology are mediated by eotaxin. In healthy subjects, eotaxin strongly impacts executive functioning and multiple cognitive domains. In schizophrenia, peripheral levels of eotaxin strongly impact both negative symptoms and psychosis (hallucinations and delusions), and these eotaxin effects are mediated by impairments in frontal functioning, memory, sustained attention, and FTD. Eotaxin is an endogenous cognitive deteriorating chemokine (ECDC) and a novel therapeutic target for age-related cognitive decline and schizophrenia as well.

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.

Two new scales of formal thought disorder in schizophrenia

Information provided by patients and respective carers may help to understand formal thought disorder (FTD) in schizophrenia. Two scales, one for patients (FTD-patient) and one for carers (FTD-carer), were constructed to assess pragmatics, cognitive, paralinguistic, and non-verbal aspects of communication. In the first scale the patients themselves assess their verbal communication; in the second scale the carer assesses the speech of the respective patient. Both scales exhibited internal reliability and evidence of good test-retest reliability. Higher total scores on both scales (FTD-patient and FTD-carer) were significantly associated with positive FTD, but not with negative FTD. Principal component analysis of the scales yielded a multidimensional structure. It is suggested that FTD in schizophrenia may be associated with a range of deficits (e.g. pragmatics, lexical activation, working memory, sustained attention). These scales, in conjunction with the clinician's assessment, can provide a more comprehensive picture of FTD in schizophrenia, revealing its dimensions and making it possible to establish associations between symptoms of FTD and neuropsychological, neurophysiologic, and neuroimaging data. In addition, they provide service users' and carers' perspectives for the assessment of communication in schizophrenia.

Working memory in schizophrenia and mania: correlation with symptoms during the acute and subacute phases

OBJECTIVE

The aims of this study were to examine working memory in the acute subacute phase of schizophrenia and mania and to examine correlations between working memory and specific symptom domains.

METHOD

Visuospatial working memory and symptom profiles were assessed in three groups (schizophrenia group, n= 19; mania, n= 12; controls, n= 19) on two occasions separated by 4 weeks.

RESULTS

Both patient groups had significant deficits on working memory compared to the well controls and the schizophrenia and mania groups were equally impaired. All groups showed equivalent improvement over time. In the patient groups, impaired working memory was significantly correlated with the presence of both negative symptoms and positive thought disorder.

CONCLUSION

Impaired working memory is found in both schizophrenia and mania during the acute subacute phases. Further research is required in order to clarify the neurocognitive mechanisms linking impaired working memory with both negative symptoms and positive thought disorder.

Factor analysis of the Communication Disturbances Index

The present study utilized factor analysis to investigate possible underlying processes in schizophrenic thought disorder. Using the Communication Disturbances Index [CDI; Arch. Gen. Psychiatry, 53, (1996) 358], a measure of disruption in the communication of meaning from speaker to listener, we examined the speech of 58 stable schizophrenia outpatients for six different types of referential communication disturbances. We calculated instances of disturbance per 100 words and then factor-analyzed our data using the SAS statistical package. Principal components analysis with an oblique rotation produced both a two- and a three-factor solution, depending on factor inclusion criteria. In the three-factor solution, the first two factors reflected weaknesses in language structural organization and in concept-boundary definition, respectively. The third factor appeared to reflect weaknesses in specific facets of memory functioning. In the two-factor solution, the aforementioned structural organization and concept-boundary definition factors were combined into a single executive functioning factor. Results from the study may be heuristic in the development of models of language disturbance in schizophrenia patients.

Prevalence and description of psychotic features in bipolar mania

Psychotic symptoms are common in both the manic and depressive phases of bipolar disorder. More than half of patients with bipolar disorder will experience psychotic symptoms in their lifetime. Grandiose delusions are the most common type of psychotic symptom, but any kind of psychotic symptom, including thought disorder, hallucinations, mood-incongruent psychotic symptoms, and catatonia can present as part of a manic episode. Psychotic symptoms suggest poor prognosis when they occur in the absence of affective symptoms. However, psychotic symptoms can mask affective symptoms and make the distinction between manic-depressive illness and other psychiatric disorders difficult, especially in minorities. Careful assessment of prior psychiatric history, family history, and treatment response can aid in the differentiation of affective disorders with psychotic features from psychotic disorders.

Positive and negative symptoms in the psychoses: principal components analysis of items from the Scale for the Assessment of Positive Symptoms and the Scale for the Assessment of Negative Symptoms

The present study investigated the factor structure of the items contained in Andreasen's scales for the assessment of positive and negative symptoms (SAPS and SANS) by use of a series of principal components analyses (PCAs) with oblique rotations of the axes. It was found that the structure could be summarized by three major components labeled negative symptoms, thought disorder, and delusions/hallucinations. Dimensionality could meaningfully be increased to five components. Negative symptoms was found to separate into two components that we labeled negative signs and social dysfunctions. The delusions/hallucinations factor could be separated into two components, delusions and hallucinations, with "loss of boundary" delusions being related to both factors. Delusions of persecution were independent of other symptoms. The thought disorder factor did not decompose meaningfully within the investigated dimensionality. A two-factor solution did not explain the correlation between symptoms adequately. The results do not support the simple dichotomy between positive and negative symptoms in psychosis, but suggest that a wider dimensional concept may be more useful in future studies.

Positive and negative symptoms in the psychoses. Re-analysis of published SAPS and SANS global ratings

The validity of the simple dichotomy between positive and negative symptoms was examined by reanalysing the results of published studies using global ratings from Andreasen's SAPS and SANS. Global ratings from our own sample of 114 diagnostically heterogenous psychotic patients were also analysed. In none of the studies was a simple positive-negative dichotomy an adequate representation of symptom structure. The most commonly occurring structure consisted of three independent groups: Hallucinations/Delusions, Positive Thought Disorder and Negative Symptoms. These findings applied to both manic and schizophrenic groups of patients. An important implication of these results for future studies is that combining positive symptoms into a single scale is inappropriate because possibly differential relationships between Hallucinations/Delusions and Thought Disorder and a variety of external measures may be obscured by such a means of data reduction.

Ordering thoughts on thought disorder

A common denominator can be found permeating thought disorder at various levels--the lack of executive planning and editing. With data available from aphasiology and neuropsychology, certain features of thought disorder can be reinterpreted as being consistent with dysfunction of the frontal lobe. It is hypothesised that thought disorder may reflect a dysfunction of the cortical-subcortical loops that project into the pre-frontal cortex. The hypothesis predicts that thought-disordered patients will have impaired performance on tests of frontal lobe function, regardless of diagnosis.