Thought-disordered Schizophrenic Patients Research Articles

Further evidence for “hyper-priming” in thought-disordered schizophrenic patients using repeated masked category priming

Background Previous research has yielded evidence for enhanced semantic priming in formal thought-disordered schizophrenia patients, a result that fits well with the hypothesis of disinhibited processes of spreading activation in this population. Methods The present study tested this hypothesis by using masked repetition priming, which yields reversed semantic priming effects in healthy participants. Assuming that performance in this paradigm relies on a balance between activation and inhibition processes in healthy participants, we compared formal thought-disordered schizophrenia patients, non-thought disordered schizophrenia patients, and healthy controls. Results For thought-disordered schizophrenia patients, we found a large positive semantic priming effect for dominant category exemplars (primed by the category name), whereas healthy controls had a small negative effect. For non-thought disordered patients, we found a non-significant, numerically positive effect. Conclusions This result yields further evidence for the lack of inhibitory processes in thought-disordered patients.

Double-decision lexical tasks in thought-disordered schizophrenic patients: A path towards cognitive remediation?

It has been shown that schizophrenics have certain difficulties in the processing of semantic context. These difficulties have usually been evaluated using lexical decision tasks with semantic priming. In this study, we chose to examine the idea of an abnormality in the early stages of semantic context processing in thought-disordered schizophrenics using two double lexical decision tasks: one with a high (25%) and one with a low (15%) proportion of related words to assess the participants’ competency in controlled and possibly also more automatic context processing. The results obtained in 40 control participants and 40 schizophrenic patients revealed no significant differences in the amplitude of semantic priming between the two groups. These results suggest that, in the disorganized schizophrenic subjects evaluated in this study, the context processing processes mobilized by the employed tasks were unimpaired.

Semantic context-processing deficit in thought-disordered schizophrenic patients: Evidence from new semantic priming paradigms

Introduction. Disorders in the processing of the semantic context are now a well-established phenomenon in thought-disordered (TD) schizophrenic patients, and have been revealed especially well by studies that have made use of the experimental paradigm of lexical decision tasks coupled with semantic priming. The main question addressed by this study was the evaluation of the experimental conditions under which TD schizophrenic patients are able to deploy cognitive strategies for semantic context processing. Methods. We studied semantic priming in two double lexical decision tasks (i.e., involving the explicit processing of the prime word) using a sequential presentation of words (stimulus onset asynchrony; SOA 500?ms) with a different proportion of related words (Experiment 1 with 25% vs. Experiment 2 with 15%) in 15 TD schizophrenic and 15 normal participants. Results. The results showed no significant differences between the semantic priming of TD schizophrenic and normal participants for Experiment 1, unlike Experiment 2 in which we observed a significant reduction of the amplitude of semantic priming in TD schizophrenic patients. The results of Experiment 1 contrast with those obtained previously (Besche et al., 1997) using a classical lexical decision task (implicit processing of the prime word) which also contained 25% related words. Conclusions. Experimental variables, such as the cognitive processing required by the prime word or the proportion of related words or the way they are manipulated, all seem to influence the emergence of semantic priming abnormalities in TD schizophrenic patients.

Increased automatic spreading of activation in thought-disordered schizophrenic patients

Previous research on semantic priming in schizophrenia has produced conflicting findings. While several studies provided evidence for an enhanced cognitive spreading of activation in schizophrenia patients with formal thought disorder, other research has failed to replicate. The aim of the present study was to resolve some of the ambiguities in the literature. Thirty-two schizophrenic patients (12 with and 20 without symptoms of formal thought disorder according to the PANADSS) and 65 healthy controls were compared in a semantic priming task using word pronunciation. Irrespective of baseline condition (neutral or unrelated condition) patients with formal thought disorder (TD) exhibited a significantly greater indirect semantic priming effect than both non-TD patients and healthy controls. Known confounding variables such as length of illness, neuroleptic dosage and psychomotor slowness did not moderate priming. Results further strengthen the spreading activation model of formal thought disorder put forward by Maher/Manschreck and Spitzer. Data indicate that hyper-priming is not confined to lexical decision tasks. Possible reasons why several studies have failed to replicate greater priming in TD schizophrenic patients are discussed.

Information processing deficits in withdrawing alcoholics.

Prepulse inhibition (PPI) of the acoustic startle response (a reduction in response to an intense, startling stimulus (the pulse) if preceded by 30-150 ms by a weaker, non-startling stimulus) is an established model to index information processing deficits in thought-disordered schizophrenic patients. The present study aimed to investigate the influence of alcohol withdrawal on the PPI effect. Eight withdrawing alcoholic patients underwent testing for PPI of the acoustic startle response (defined as percentage reduction of the response over pulse-alone stimulus; prepulses 15 dB above the background) on three occasions (1, 3 and 7 days following the last drink). The results demonstrated remarkably low levels of PPI on days 1 and 3, with this being very robust in three patients who had a history of delirium tremens; there was a trend towards normalization of PPI on day 7. This study, although preliminary, suggests strongly that there is a deficit in the filtering of sensory information in alcohol-dependent patients undergoing alcohol withdrawal. This was most apparent in those with a history of delirium tremens. Further studies are needed to define the cause and chronicity of these deficits.

Enhanced semantic priming in thought-disordered schizophrenic patients using a word pronunciation task

Previous research on semantic priming in schizophrenia has produced contradictory findings. For the present study, it was intended to resolve some of the ambiguities in the literature. Using a semantic priming task with word pronunciation, evidence is provided that thought-disordered schizophrenic (TD) patients exhibit significantly increased semantic priming as compared to healthy and psychiatric controls. Results suggest that enhanced semantic priming is not confined to tasks that require lexical decision. Moreover, results indicate that TD schizophrenic patients suffer from a decay of hierarchical thinking, i.e. TD schizophrenics reveal a tendency to process the less meaningful rather than the dominant aspects of external information. Priming effects for the inferior meaning of homograph words (for example, ‘dance’ is an inferior, and ‘game’ is a superior associate of the word ‘ball’) were significantly greater compared to healthy controls and non-TD schizophrenics. Results were not moderated by sociodemographic background variables, psychomotor slowing and psychopathological symptoms other than thought disorder.

'Hyper-priming' in thought-disordered schizophrenic patients.

A number of studies have suggested that indirect semantic priming is enhanced in thought-disordered schizophrenics. However, research on direct semantic priming has produced conflicting results. The aim of the present study was to resolve some of the ambiguities of previous findings. For the present study, 44 schizophrenic patients were split according to the presence of associative loosening into a positive thought-disordered (TD) and non-positive thought-disordered (NTD) group. Thirty healthy subjects and 36 psychiatric patients served as controls. Schizophrenics displayed increased indirect semantic priming compared with psychiatric controls. When subtyping the sample, TD-patients exhibited significantly enhanced indirect semantic priming compared with healthy and psychiatric controls as well as NTD-patients. Overall slowing was found to be independent of priming effects. Medication, age and chronicity of the schizophrenic illness did not modulate priming. In line with Spitzer and Maher it is inferred that disinhibited semantic networks underlie formal thought disorder in schizophrenia. For future research, it would be appropriate to: employ indirect semantic priming rather than direct semantic priming conditions; and, pay more attention to potential moderators of the priming effect, most importantly, the prime display duration and the length of the stimulus onset asynchrony.

Thought Disorder in Schizophrenia: A Reappraisal of Older Formulations and an Overview of Some Recent Studies

Introduction. Formal thought disorder, as manifested in disorganised speech, is a cardinal symptom of schizophrenia. Method. In this review we examine several older explanations of thought disorder and consider newer cognitive accounts. Results. Older formulations often were not mechanistic and simply redescribed the phenomenon under study. Direct comparisons of thought-disordered schizophrenic patients and jargon aphasic patients indicated that the groups were not similar, as they differed on a number of language variables, including naming and comprehension. Later attentional models also had limitations. Correlations between thought disorder and ''attentional'' measures were often only moderate and the tests or scales used to assess attention or thought disorder may not have accurately measured these constructs. Recent working memory models have lacked convergent validity in that patients with frontal lobe damage and working memory problems do not exhibit thought disorder and that single word association and priming studies elicit abnormalities in schizophrenic patients, findings at odds with the view that thought disorder is a discourse planning problem. In our own series of studies we found compelling evidence that thought disorder may be related to various impairments in semantic processing. These impairments were especially evident on semantic fluency tasks. In fact it was the latter, rather than working memory or attentional tests, that predicted thought disorder. Moreover, we were able to provide a mechanistic account of thought disorder based on qualitative abnormalities in semantic priming paradigms. Conclusions. Patients with thought disorder displayed lack of priming for highly associated within-category words, suggesting that they could not access them in a timely and semantically relevant manner. The literature also has implications for understanding cognitive architecture. Although vocabulary and naming abilities were relatively normal in schizophrenic patients, cognitive maps of semantic space, as determined by multidimensional scaling analyses, indicated disorganisation among semantic entities. These results imply that the size of the lexicon is dissociable from the organisation of the lexicon. In schizophrenia in particular it appears that the latter, rather than the former, is more perturbed.

Impairment of semantic categorization processes among thought-disordered schizophrenic patients.

To explore semantic categorization strategies in patients with schizophrenia. A short-term memory-recognition task that reveals the effects associated with categorization was created and applied to 2 groups of patients with schizophrenia and depression. Only the schizophrenic subgroup with formal thought disorder (measured using Andreasen's Thought, Language, and Communication [TLC] scale) exhibited a deficiency in semantic categorization strategies during the task. These results support the hypothesis of the impairment of the processes involved in the processing of contextual information in patients with schizophrenia who suffer from formal thought disorder.

Associative semantic network dysfunction in thought-disordered schizophrenic patients: Direct evidence from indirect semantic priming

The characteristics of the spread of semantic activation in associative networks in normal subjects, thought-disordered (TD) and nonthought-disordered (NTD) schizophrenic patients with respect to time and semantic distance are examined. Direct and indirect semantic priming effects at two stimulus onset asynchronies (SOA) in a lexical decision task reveal that semantic associations spread further and faster in TD schizophrenic patients than in normal controls and in NTD schizophrenic patients. From a methodological point of view, indirect semantic priming at short prime-target intervals appears to be the best indicator of associative network dysfunction. The findings are discussed within the framework of current research on the effect of dopamine on the signal-to-noise ratio in cortical neural networks. Data suggest that semantic associative memory operates at a comparatively lower signal-to-noise ratio in thought-disordered schizophrenic patients.

Conversation skills training of thought-disordered schizophrenic patients through attention focusing

An attention-focusing procedure was designed as discrete trials and multiple prompts with contingent social reinforcement to facilitate the acquisition of conversational skills in thought-disordered schizophrenic patients. Three patients with DSM-III-R diagnoses of schizophrenia completed a standard social skills training program and the attention-focusing procedure in multiple baseline experimental designs. While social skills training had little effect on the acquisition of skills, patients who completed the attention-focusing procedure significantly increased performance of conversational skills and showed some generalization of trained behaviors.

Psychological construing and thought disorder: another test of the 'difficulty' hypothesis.

Two versions of the grid test of thought disorder were derived which used similar elements, and were of equal difficulty, but one of which employed psychological, and the other non-psychological, constructs. They were administered to thought-disordered schizophrenic patients and to psychiatric and normal controls. On one measure (consistency), although not on the other (intensity), the results strongly supported the hypothesis that thought-disordered patients are maximally disordered in the area of psychological construing. The results support those of an earlier study (McPherson et al. 1975) and are compatible with those theories which postulate a role for social factors in the aetiology of thought disorder.

Conceptual structure in thought-disordered schizophrenics.

“Thought-disorder” in schizophrenia was initially a psychiatric concept derived from clinical observation. As crystallized in standard psychiatric authorities, say Mayer-Gross, Slater and Roth (1954) the primary features of the talk (and inferentially the thinking) of thought-disordered schizophrenic patients are: (i)Inconsequential following of side issues.(ii)Tendencies for the thought to be directed by alliterations, analogies, clang associations, associations with accidents of the speaker's environment, symbolic meanings, and the condensation of several (perhaps mutually contradictory) ideas into one.(iii)Words used out of context, e.g. concrete meanings taken where abstract meanings would be appropriate.(iv)Clinging to unimportant detail.(v)The use of laconic answers, e.g. I don't know, maybe, perhaps—indicative of emptiness and vagueness of ideas.(vi)Thought is generally marked by gaps, poverty, indefiniteness and vagueness.(vii)Indications of thought-blocking.(viii)Indications of pressure of thoughts.