A rating scale for the assessment of objective and subjective formal thought and language disorder (TALD)

Formal thought disorder (FTD) is a core syndrome of schizophrenia. However, patients with other diagnoses, such as mania and depression amongst others, also present with FTD. We introduce a novel, comprehensive clinical rating scale, capturing the full variety of FTD phenomenology including subjective experiences. The 30-item Thought and Language Disorder (TALD) scale is based on a detailed review of the literature, encompassing all formal thought disorder symptoms reported from the early 20th century onwards. Objectively observable symptoms as well as subjective phenomena were included. Two hundred and ten participants (146 patients ICD-10 diagnoses: depression n. = 63, schizophrenia n. = 63, mania n. = 20; 64 healthy control subjects) were interviewed and symptoms rated with the TALD, TLC, HAMD, YMRS and SAPS/SANS. A principal component analyses was performed for the TALD to differentiate sub-syndromes. The principal component analysis revealed four FTD factors; objective and subjective as well as positive and negative factor dimensions. The correlation analyses with the TLC and the SAPS/SANS FTD sub-scores demonstrated the factor validity for the objective factors. The different diagnoses showed a distinct pattern of symptom severity in each of the factors, with mania patients exhibiting the highest value in the positive, objective dimension. The scale showed good psychometric results, which makes it a practicable, nosologically-open instrument for the detailed assessment of all FTD dimensions. The results strengthen the importance of subjective symptom assessment reported by the patient.DFG (project no. Ki 588/6-1)Scopu

Is formal thought disorder in schizophrenia related to structural and functional aberrations in the language network? A systematic review of neuroimaging findings

Formal thought disorder (FTD) is a core feature of schizophrenia, a marker of illness severity and a predictor of outcome. The underlying neural mechanisms are still a matter of debate. This study aimed at 1) reviewing the literature on the neural correlates of FTD in schizophrenia, and 2) testing the hypothesis that FTD correlates with structural and functional aberrations in the language network. Medline, PsychInfo, and Embase were searched for neuroimaging studies, which applied a clinical measure to assess FTD in adults with schizophrenia and were published in English or German in peer-reviewed journals until December 2016. Of 412 articles identified, 61 studies were included in the review. Volumetric studies reported bilateral grey matter deficits (L > R) to be associated with FTD in the inferior frontal gyrus, the superior temporal gyrus and the inferior parietal lobe. The same regions showed hyperactivity in resting state functional magnetic resonance imaging (fMRI) studies and both hyper- and hypoactivity in fMRI studies that employed semantic processing or free speech production tasks. Diffusion tensor imaging studies demonstrated white matter aberrations in fibre tracts that connect the frontal and temporo-parietal regions. FTD in schizophrenia was found to be associated with structural and functional aberrations in the language network. However, there are studies that did not find an association between FTD and neural aberrations of the language network and regions not included in the language network have been associated with FTD. Thus, future research is needed to clarify the specificity of the language network for FTD in schizophrenia

Differences in single positive formal thought disorder symptoms between closely matched acute patients with schizophrenia and mania

Formal thought disorders (FTD) are a hallmark diagnostic feature of schizophrenia (SZ) and (bipolar) mania (MA). FTD can be separated into positive (pFTD) and negative dimensions. It is unclear whether there are differences in pFTD on a single symptom level between acutely ill patients with SZ and MA, which cannot be attributed to cognitive impairment. We compared single pFTD symptoms in two groups of acutely ill patients with ICD-10 bipolar mania and schizophrenia, closely matched for age, sex, pFTD TALD score, verbal IQ and neuropsychological test performance (executive function, verbal fluency, attention, and working memory). SZ patients had higher severity of the TALD symptoms 'perseverations' and 'poverty of content of speech' than those with MA (Mann-Whitney U, significant, Bonferroni corrected). Speech in acute SZ patients differs from MA in that it conveys little information and adheres to previously mentioned ideas and topics. Matching for confounding variables, such as IQ and cognition, is important when comparing patients with different diagnoses

The role of the left and right inferior frontal gyrus in processing metaphoric and unrelated co-speech gestures

Gestures are an integral part of in-person conversations and complement the meaning of the speech they accompany. The neural processing of co-speech gestures is supported by a mostly left-lateralized network of fronto-temporal regions. However, in contrast to iconic gestures, metaphoric as well as unrelated gestures have been found to more strongly engage the left and right inferior frontal gyrus (IFG), respectively. With this study, we conducted the first systematic comparison of all three types of gestures and resulting potential laterality effects.During collection of functional imaging data, 74 subjects were presented with 5 s videos of abstract speech with related metaphoric gestures, concrete speech with related iconic gestures and concrete speech with unrelated gestures. They were asked to judge whether the content of the speech and gesture matched or not.Differential contrasts revealed that both abstract related and concrete unrelated compared to concrete related stimuli elicited stronger activation of the bilateral IFG. Analyses of lateralization indices for IFG activation further showed a left hemispheric dominance for metaphoric gestures and a right hemispheric dominance for unrelated gestures.Our results give support to the hypothesis that the bilateral IFG is activated specifically when processing load for speech-gesture combinations is high. In addition, laterality effects indicate a stronger involvement of the right IFG in mismatch detection and conflict processing, whereas the left IFG performs the actual integration of information from speech and gesture

Psychiatric symptoms are differentially associated with verbal fluency performance in patients with schizophrenia and affective disorders

Background Despite verbal fluency (VF) being a common task in psychiatric research, there is very little consensus on the nature of VF deficits in psychiatric populations and their implications for our knowledge about cognitive and specifically linguistic functioning in these populations. Previous studies have found that negative symptoms, including alogia, are associated with poorer overall VF production in patients with schizophrenia (SCH), while studies investigating positive symptoms, including formal thought disorder, have yielded mixed results. Because most studies didn’t analyze additional VF measures such as clustering and lexical characteristics, it remains unclear whether the association between negative and positive symptoms and VF performance in patients with schizophrenia reflects abnormalities in linguistic and/or semantic processing or other aspects of cognition. Furthermore, it is uncertain whether these associations are specific to patients with schizophrenia, while the associations with manic and depressive symptoms are understudied. Methods We recruited 58 German-speaking inpatients diagnosed with either schizophrenia (N = 36), bipolar disorder (BD; N = 10), or major depression (DEP; N = 12). All patients were assessed on conventional symptom scales including the SANS/SAPS, HAMD, and YMRS, and were further administered the semantic (SF; animals) and letter (LF; P) fluency tasks (60 s). The following dependent variables were analyzed: correct words, error rate, response latencies, switching rate, cluster size, idiosyncratic word production rate, and word frequency. Results BD produced significantly larger clusters and had significantly higher idiosyncratic word production rates on SF compared to both SCH and DEP, while overall word frequency on SF differentiated between all patient groups. Overall negative symptomatology and specifically alogia were negatively associated with overall performance and positively with between-cluster response latencies on SF. Alogia was not significantly associated with other VF variables. Cluster size and overall word frequency on SF were positively associated with depressive and negatively with manic symptoms, idiosyncratic word production rate on SF was positively associated with manic symptoms, while positive symptoms were only negatively associated with the frequency of the first three words on SF. Discussion Previous evidence for an association between negative and positive symptoms, and VF performance in SCH has been to some extent replicated in a diverse psychiatric sample. Because alogia was not significantly associated with VF variables other than overall productivity and between-cluster response latencies, we found no evidence that alogia is associated with deficient processing within the semantic memory or mental lexicon. Yet, its positive association with between-cluster response latencies possibly suggests that alogia reflects transdiagnostic dysfunctional connectivity between the prefrontal and temporal cortices and, thus, inefficient lexical access. Furthermore, clinical levels of mania were associated with normal cluster sizes, in line with one previous study. Intriguingly, cluster sizes did not differ between SCH and DEP, indicating a similar level of the semantic deficit with possibly different underlying mechanisms. Additionally, manic symptoms were associated with relatively unusual (but appropriate) word production, indicating aberrant saliency of words during lexical access in mania. Further research regarding word frequency is needed to adequately interpret those results. Finally, LF performance was diagnostically and symptomatically unremarkable

Support for a novel, simple method for calculating word frequency of output on language production tasks

Introduction: Studies consistently report that patients with schizophrenia exhibit qualitative abnormalities on language production tasks. These abnormalities are possibly associated with the severity of psychotic symptoms. Despite this, some studies have conflictingly suggested that patients with schizophrenia exhibit similar word frequency (WF) effects on lexical tasks compared to healthy subjects. Given that previous studies calculated WFs from language corpora, we aimed to investigate the relationship between WF and psychotic symptoms using a novel, simple method for calculating WF. Methods: Thirty-six patients with schizophrenia were included in the study. The severity of positive symptoms was measured using the Scale for the Assessment of Positive Symptoms (SAPS). One semantic and one letter fluency task were administered with the patients instructed to produce as many animal names and words beginning with the letter p in 60 s, respectively. Every response in the output was assigned (1) a corpus-based WF, extracted from the German-language lexical database dlexDB, and (2) a within-sample WF. The within-sample WF was calculated as the raw number of participants who produced the word. Spearman’s correlations were computed between the WF variables and symptoms. Results: Corpus-based WF exhibited skewed, kurtic, and/or non-normal distribution. Contrastingly, within-sample WF displayed normal, non-skewed, and non-kurtic distribution. There were no significant correlations between corpus-based WF and symptoms on both tasks. Conversely, within-sample WF on semantic fluency was significantly negatively and weakly correlated with the global SAPS score, as well as subscales measuring delusions and bizarre behavior. Further, within-sample WF on letter fluency was significantly positively and weakly correlated with the subscale measuring bizarre behavior of the SAPS scale. Conclusion: The differences in the data distribution patterns between corpus-based WF and within-sample WF indicate that different methodological frameworks may have better use of one or the other variable type. Further, significant correlations with positive symptoms were observed only for within-sample WF. It can be concluded that within-sample WF may be more appropriate for analyzing verbal fluency output in psychiatric research compared to corpus-based WF