Thought disorder in adolescent-onset schizophrenia

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.

A hierarchical finite mixture model that accommodates zero-inflated counts, non-independence, and heterogeneity

A number of mixture modeling approaches assume both normality and independent observations. However, these two assumptions are at odds with the reality of many data sets, which are often characterized by an abundance of zero-valued or highly skewed observations as well as observations from biologically related (i.e., non-independent) subjects. We present here a finite mixture model with a zero-inflated Poisson regression component that may be applied to both types of data. This flexible approach allows the use of covariates to model both the Poisson mean and rate of zero inflation and can incorporate random effects to accommodate non-independent observations. We demonstrate the utility of this approach by applying these models to a candidate endophenotype for schizophrenia, but the same methods are applicable to other types of data characterized by zero inflation and non-independence.

Thought disorder in mid-childhood as a predictor of adulthood diagnostic outcome: findings from the New York High-Risk Project

BACKGROUND

Thought disorder has been proposed as an indicator of schizotypy, which is considered to be necessary but not sufficient for the development of schizophrenia. It is unclear whether thought disorder is an indicator of susceptibility (i.e. an endophenotype) for schizophrenia. The goal of the present study was to elucidate the role of thought disorder in relation to schizotypy by examining its presence in high-risk individuals during mid-childhood. Method The sample consisted of 265 subjects drawn from the New York High-Risk Project. Individuals at high risk for schizophrenia (i.e. offspring of parents with schizophrenia) were compared with individuals at low risk for schizophrenia (i.e. offspring of parents with affective disorder or offspring of psychiatrically normal parents). Videotaped interviews were rated for thought disorder using the Scale for the Assessment of Thought, Language, and Communication (TLC). The same subjects were administered diagnostic interviews in late adolescence/early adulthood.

RESULTS

Although positive thought disorder was equally present in subjects with affective and non-affective psychoses, negative thought disorder (namely, poverty of speech and poverty of content of speech) was elevated only in subjects with schizophrenia-related psychosis. Logistic regression analyses revealed that negative thought disorder added to the prediction of schizophrenia-related psychosis outcomes over and above positive thought disorder.

CONCLUSIONS

These findings suggest that negative thought disorder may have a specific association with schizotypy, rather than a more general association with psychosis. The findings also support consideration of negative thought disorder as an endophenotypic indicator of a schizophrenia diathesis.

Thought disorder and communication deviance as predictors of outcome in youth at clinical high risk for psychosis

OBJECTIVE

Given the fundamental role of thought disorder in schizophrenia, subtle communication disturbance may be a valuable predictor of subsequent development of psychosis. Here we examined the contribution of thought and communication disturbance to the prediction of outcome in adolescents identified as putatively prodromal for psychosis.

METHOD

Transcribed speech samples were elicited from 105 adolescents (54 identified as being at clinical high risk for a first episode of psychosis [CHR], and 51 demographically comparable comparison subjects) and coded for formal thought disorder (FTD) and linguistic cohesion. We then examined the association of baseline FTD/cohesion with conversion to psychosis and social and role outcome at follow-up, approximately 1 year later.

RESULTS

At baseline, CHR patients who subsequently converted to psychosis (CHR+) showed an elevated rate of illogical thinking and poverty of content (POC) in their speech, relative to both typically developing controls and CHR patients who did not convert to psychosis (CHR-). CHR+ youth also used significantly less referential cohesion at baseline, indicating that they provide fewer references to persons, objects, or events mentioned in preceding utterances. Multiple regression models indicated that, among measures of FTD/cohesion, illogical thinking was uniquely predictive of subsequent conversion to psychosis, whereas POC and referential cohesion were significant predictors of social and role functioning, respectively.

CONCLUSIONS

Despite the absence of fully psychotic symptoms, putatively prodromal individuals evidence signs of communication disturbance that are qualitatively similar to those seen in schizophrenia and are predictive of both conversion to psychosis and psychosocial outcome. These findings suggest that FTD measures have prognostic significance for at-risk youth.

The Genetic Basis of Thought Disorder and Language and Communication Disturbances in Schizophrenia

Thought disorder as well as language and communication disturbances are associated with schizophrenia and are over-represented in clinically unaffected relatives of schizophrenics. All three kinds of dysfunction involve some element of deviant verbalizations, most notably, semantic anomalies. Of particular importance, thought disorder characterized primarily by deviant verbalizations has a higher recurrence in relatives of schizophrenic patients than schizophrenia itself. These findings suggest that deviant verbalizations may be more penetrant expressions of schizophrenia susceptibility genes than schizophrenia. This paper reviews the evidence documenting the presence of thought, language and communication disorders in schizophrenic patients and in their first-degree relatives. This familial aggregation potentially implicates genetic factors in the etiology of thought disorder, language anomalies, and communication disturbances in schizophrenia families. We also present two examples of ways in which thought, language and communication disorders can enrich genetic studies, including those involving schizophrenia.

Brain/behavior Asymmetry in Schizophrenia: A MEG Study of Cross-modal Semantic Priming

Semantic priming has long been used to investigate how concepts and ideas are related at the level of language, and has become a convenient tool for assessing conceptual and semantic dysfunction in cognitive disorders, including schizophrenia. The study of semantic priming in schizophrenia has led to diverse results: enhanced priming, reduced priming, and priming equivalent to that found in nonpsychiatric comparison groups. A number of hypotheses have been proposed to explain some of the observed deficits in schizophrenia patients. For example, difficulties in word recognition may be due to hyperactivation of too many lexical representations or to a failure to inhibit lexical competitors. One way to distinguish between these possible explanations is to move beyond reliance on behavior alone and to examine the neural processes involved in lexical recognition. Here we present a magnetoencephalographic study of semantic priming in schizophrenia. Importantly, schizophrenia patients and healthy controls did not differ in performance on a priming task. We show that normal behavioral performance can occur in a context of aberrant neural responses. These findings suggest that normal behavioral responses in schizophrenia can be achieved through neural mechanisms that differ from those seen in the psychiatrically well brain.

The power of linkage analysis of a disease-related endophenotype using asymmetrically ascertained sib pairs

A linkage study of a qualitative disease endophenotype in a sample of sib pairs, consisting of one disease affected proband and one sibling is considered. The linkage statistic compares marker allele sharing with the proband in siblings with an abnormal endophenotype to siblings with the normal endophenotype. Expressions for the distribution of this linkage statistic, in terms of the recombination fraction are derived and (1) the genetic parameter values (allele frequency and endophenotype and disease penetrance) and (2) the abnormal endophenotype rates in the population and in classes of relatives of disease affected probands. It is then shown that when either the disease or the abnormal endophenotype has additive penetrance, the expressions simplify to a monotonic function of the difference between abnormal endophenotype rates in siblings and in the population. Thought disorder is considered as a putative schizophrenia endophenotype. Forty sets of genetic parameter values that correspond to the known prevalence values for thought disorder in schizophrenic patients, siblings of schizophrenics and the general population are evaluated. For these genetic parameter values, numerical results show that the test statistic has>70% power (α = 0.0001) in general with a sample of 200 or more proband-sibling pairs to detect the linkage between a marker (θ = 0.01), and a locus pleiotropic for schizophrenia and thought disorder.

Influence of diagnostic classification on gender ratio in schizophrenia - a meta-analysis of youths hospitalized for psychosis

BACKGROUND

The research literature on hospital admissions for psychoses in youths was reviewed in order to test whether there was a gender ratio discrepancy in diagnostic subgroups; the effect of the diagnostic criteria classification on this measure was also investigated.

METHOD

A meta-analysis was conducted on 12 primary studies by assessing the male/female odds ratio (OR) in the schizophrenia and mood disorders with psychosis subgroups as well as the amount of variability between studies. Study inclusion criteria were: patients between the ages of 8 and 19, at least 15 patients with psychosis and a standardized diagnostic criteria classification system such as DSM, ICD or RDC.

RESULTS

The male/female OR measured in this meta-analysis implies that a male subject with psychosis is 1.7 times as likely to obtain a diagnosis of schizophrenia; conversely, a female subject with psychosis is 2.1 times as likely to be assigned in the mood disorders with psychosis subgroup. Disparity in diagnostic criteria nomenclature (ICD-9 vs. DSM) could account for a statistically significant difference in male/female OR for the schizophrenia subgroup in a subset of 11 studies.

CONCLUSIONS

Under the narrower definition of schizophrenia in studies using DSM diagnostic criteria classification, the shift towards a greater proportion of patients diagnosed with mood disorders with psychosis could be explained by the time criteria; the simultaneous emergence of the gender ratio difference is discussed. This study shows that subtle changes in diagnostic criteria in psychiatric illnesses can greatly influence observational data pertaining to youths.

Thought disorder in childhood schizophrenia: replication and update of concept

OBJECTIVES

To examine whether measures of thought disorder differentiated schizophrenic from normal children and to examine the relationship of these measures with developmental and cognitive factors.

METHOD

The speech samples of 88 schizophrenic and 190 normal children, aged 9 to 13 years, were coded with the Kiddie Formal Thought Disorder Rating Scale and Halliday and Hassan's analysis of cohesion.

RESULTS

Above and beyond differences in mental age, gender, and neuroleptic status, the patients had significantly more formal thought disorder (FTD) and cohesive deficits than the normal children matched by mental age. The younger schizophrenic and normal children had significantly more thought disorder than the older children with these diagnoses. Combined FTD and cohesion scores correctly identified 76% of schizophrenic and 88% of normal children with little variability across mental age. The thought disorder measures generated 2 independent components: FTD and cohesion.

CONCLUSIONS

Thought disorder measures that include both FTD and cohesion provide a quantitative diagnostic tool of childhood-onset schizophrenia.

Behavioral science foundations of the Rorschach test: research and clinical applications

Never without its critics, the Rorschach Test continues to be widely used in clinical settings. The test continues to be criticized vigorously. Rorschach critics appear to fall into two broad groups: those leveling valid methodological concerns about the test s behavioral science foundations and method critics who appear to deny the validity of the test on strictly a priori or theoretical considerations. Many critics do not appear to be acquainted with the extensive Rorschach research literature. The current paper provides an overview of several domains of applied and laboratory Rorschach behavioral science, including statistical power analysis, interobserver agreement and interrater reliability, Rorschach assessment of thought disorder, and emerging research linking Rorschach variables with diagnostic criteria from the DSM-IV, as a means of educating both adherents and detractors alike concerning the test s scientific track record and applicability to clinical assessment.