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Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Loosening of thinking as assessed by the Object Sorting Test (OST) has been found in a percentage of normal subjects but in a higher percentage of schizophrenics, and is familially transmitted in both groups. Loosening of thinking in normal subjects is not associated with evidence of impaired function or increased psychopathology, and in recognition of this, it was termed allusive thinking rather than thought disorder. Both OST-assessed loosening and concreteness of thinking were found to be present independently in a high percentage of schizophrenics, so that both were considered to contribute to schizophrenic thought disorder. The presence of OST-assessed loosening in schizophrenics would, therefore, be predicted to correlate partially rather than totally with measures of schizophrenic thought disorder. It has been suggested that OST-assessed loosening in normal subjects is due to a genetically determined reduction in strength of an inhibitory process that limits the spread of activation of semantic associations and results in a predisposition to schizophrenia. The brain event-related potential P300, which is, in part, under genetic control, may index this inhibitory process. Therefore, it was predicted that in normal subjects, P300 would correlate with OST-assessed loosening of associations. If schizophrenic thought disorder is due to a further weakening of this inhibitory process, it can be predicted that P300 in schizophrenics correlates only weakly with OST-assessed loosening of thinking, but more strongly with schizophrenic thought disorder. In a study in which P300 was elicited using a difficult selective attention task with 15 unmedicated schizophrenics and 22 healthy subjects, all three predictions were supported.
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PMID:P300 indexes thought disorder in schizophrenics, but allusive thinking in normal subjects. 844 76

An average person normally spends at least 90 min to 2 h per night dreaming. Nevertheless, memories of dream events are not retrieved while awake unless the person awoke shortly after a dream. It is hypothesized here that schizophrenic delusions initially arise because a system that normally inhibits the formation of memories of dream events is defective. Therefore, memories of dream events or fragments would be occasionally made and placed in the normal memory store. The only reason that we really know anything happened to us in the past is that we have a memory of it, and having a memory of an event is sufficient to really believe it. Therefore, the schizophrenic would believe that the dream events actually happened. It is proposed that this is the basis of primary delusions. Because memories are represented by strengthened neural connections there will be an accumulation of connections that do not correspond to reality. This accumulation may account for other symptoms of schizophrenia such as thought disorder, loosening of associations, and hallucinations. The brain trying to draw conclusions from several memories may be the basis of secondary delusions. Evidence is presented for the ideas that primary delusions are due to memories of dream events, that a substance, with vasotocin-like bioactivity, is released in the brain during dreaming and inhibits memory formation, that the lateral habenula is a brain area involved in vasotocin actions and is affected by neuroleptics, and that brain mechanisms involved in vasotocin actions show pathological alterations in schizophrenia.
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PMID:Defective inhibition of dream event memory formation: a hypothesized mechanism in the onset and progression of symptoms of schizophrenia. 966 11

Contextual effects were explored in schizophrenia patients and paired comparison subjects during a long-term face recognition task. The objective was to investigate the contextual effects on face recognition by manipulating, in the same experiment, the perceptual context of the face (intrinsic vs. extrinsic) and the task context (inclusion vs. exclusion instructions). The situation was derived from the Jacoby's [Jacoby, L.L., 1991. A process dissociation framework: separating automatic from intentional uses of memory. Journal of Memory and Language 30, 513-541] process dissociation procedure. The results showed that schizophrenia patients (N=20) presented lower performances than healthy controls (N=20) in the inclusion but not in the exclusion task. This observation emphasizes the heterogeneity of recollection and suggests that the memory impairment in schizophrenia reflects an imbalance between two mechanisms. The first is a deficit in "associative recollection", i.e., the failure to use efficiently associative information. The other is an enhanced "discriminative recollection" that impedes their capacity to process information separately from its perceptual context. In addition, correlation with symptoms suggest that the former is expressed in the loosening of associations characteristic of disorganization symptoms, whereas the latter reflects the lack of flexibility or the contextualization bias related to psychotic symptoms, i.e., delusions and hallucinations.
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PMID:Use of the process dissociation procedure to study the contextual effects on face recognition in schizophrenia: familiarity, associative recollection and discriminative recollection. 1712 45

In schizophrenia, speech production deficits in patients with positive formal thought disorder (FTD e.g. loosening of associations and derailment) have been attributed to impairments in the semantic network. The brain area implicated in the retrieval of associated (i.e. relational) concepts is the hippocampus, a key region in the psychopathology of schizophrenia. However, its role in schizophrenic speech production and FTD in particular is yet little understood. To investigate the neural correlates of associative verbal retrieval, twelve patients with schizophrenia with varying degrees of FTD and twelve matched healthy control subjects underwent a free verbal association (FVA), a semantic (SVF) and a phonological verbal fluency (PVF) task while brain activity was measured with fMRI. The tasks varied in the relational binding operations needed for linking the stimulus to the respective response. Compared to control subjects, patients revealed attenuated left hippocampal activity during both semantic word generation tasks (FVA, SVF). Contrasting verbal fluency with FVA, a failure in recruiting the anterior cingulate gyrus emerged in the patient group. A negative correlation was found between right middle temporal activity and the severity of FTD during FVA. The hippocampus seems to play a major role in word generation. In schizophrenia, attenuated hippocampal activity during semantic tasks strengthens the hypothesis of impaired relational memory processes, affecting thought and language.
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PMID:Hippocampal dysfunction during free word association in male patients with schizophrenia. 1835 25

On the 100th anniversary of the publication of Eugen Bleuler's Dementia Praecox or the Group of Schizophrenias, his teachings on schizophrenia from that seminal book are reviewed and reassessed, and implications for the current revision of the category of schizophrenia, with its emphasis on psychotic symptoms, drawn. Bleuler's methods are contrasted with Kraepelin's, and 4 myths about his concept of schizophrenia addressed. We demonstrate that (1) Bleuler's concept of schizophrenia has close ties to historical and contemporary concepts of dissociation and as such the public interpretation of schizophrenia as split personality has some historical basis; (2) Bleuler's concept of loosening of associations does not refer narrowly to a disorder of thought but broadly to a core organically based psychological deficit which underlies the other symptoms of schizophrenia; (3) the "4 A's," for association, affect, ambivalence, and autism, do not adequately summarize Bleuler's teachings on schizophrenia and marginalize the central role of splitting in his conception; and (4) Bleuler's ideas were more powerfully influenced by Pierre Janet, particularly with regard to his diagnostic category Psychasthenia, than by Sigmund Freud. We conclude that Bleuler's ideas on schizophrenia warrant reexamination in the light of current criticism of the emphasis on psychotic symptoms in the schizophrenia diagnosis and argue for the recognition of the dissociative roots of this most important psychiatric category.
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PMID:Eugen Bleuler's Dementia praecox or the group of schizophrenias (1911): a centenary appreciation and reconsideration. 2150 10

The aim of this review is to describe the potential relationship between multisensory disintegration and self-disorders in schizophrenia spectrum disorders. Sensory processing impairments affecting multisensory integration have been demonstrated in schizophrenia. From a developmental perspective multisensory integration is considered to be crucial for normal self-experience. An impairment of multisensory integration is called 'perceptual incoherence'. We theorize that perceptual incoherence may evoke incoherent self-experiences including depersonalization, ambivalence, diminished sense of agency, and 'loosening of associations' between thoughts, feelings and actions that lie within the framework of 'self-disorders' as described by Sass and Parnas (2003). We postulate that subconscious attempts to restore perceptual coherence may induce hallucinations and delusions. Increased insight into mechanisms underlying 'self-disorders' may enhance our understanding of schizophrenia, improve recognition of early psychosis, and extend the range of therapeutic possibilities.
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PMID:Schizophrenia as a self-disorder due to perceptual incoherence. 2397 19

Symptoms specific to schizophrenia include self-disturbances, delusional perception and loosening of associations. Self-disturbances in schizophrenia can be explained from the standpoint of an abnormal sense of agency, such as thought broadcasting as an over-attribution of agency and thought insertion as an under-attribution of agency. Delusional perception is often accompanied by impairment of perceptual organization; delusional mood and delusions might result from the reorganization of the fragmented perceptual field, as well as a loss of reality. Impairment of perceptual organization is frequently related to the loosening of associations.
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PMID:[Symptoms Specific to Schizophrenia]. 3017 76