UMLS:C0036341 - FACTA Search

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

The psychometric high-risk strategy represents a useful methodologic adjunct to the traditional genetic high-risk research approach in the study of the etiology and development of schizophrenia. During the past 15 years, considerable research activity has focused on psychometrically identified individuals hypothesized to be en route to schizophrenia (i.e., putative schizotypes). The Perceptual Aberration Scale (PAS) has figured prominently in such prediction-oriented psychometric high-risk work. This report examines research using the PAS completed since 1987 that has established the instrument as a valid index for detecting liability for schizophrenia (or schizotypy) and as, arguably, the schizotypy index of choice for research. These results are presented and interpreted in light of Meehl's theoretical framework of schizotypy. Other measures of and assessment devices for schizotypy (schizophrenia-related liability) are identified. Of these other measures, the Chapmans' Magical Ideation Scale and the schizophrenia liability index of Moldin and colleagues are particularly well established. Methodologic suggestions for future psychometric high-risk and other work using objective measures of schizotypic psychopathology are offered. It is strongly recommended that future studies of schizotypy (or those in the planning stages, relying on psychometric detection methods use multiple psychometric indices to tap schizotypy or use a psychometric index in association with other promising biobehavioral markers of schizophrenia liability (e.g., sustained attentional deficits, eye movement dysfunction) for maximum efficiency in both location and definition of schizotypes.
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PMID:Psychometric high-risk paradigm, perceptual aberrations, and schizotypy: an update. 819 10

The longitudinal followup strategy in high-risk research is being increasingly complemented by the use of psychosis-proneness scales to select subjects for study who might be vulnerable to schizophrenia and who show differences on laboratory measures that could act as endophenotypic markers for use in genetic investigations. Three types of experimental paradigm have been adopted, drawn from cognitive psychology, psychophysiology, and the neuropsychology of hemisphere function. Results adopting each of these approaches are examined, alongside recent factor-analytic evidence that psychosis-proneness scales currently in use tap up to four different components that map onto the clinical heterogeneity of schizophrenia (and possibly other forms of psychosis). No one of these components clearly emerges as, or points to, a single indicator of risk, though some aspect of neurocognitive functioning seems a likely candidate. Even so, it is argued, the clinical expression of vulnerability must be due to a convergence in an individual of several components of risk since individually (and notably so for "susceptibility to positive symptoms") they are very common in the healthy population. In evaluating the evidence, attention is drawn to two crucially different ways that investigators in schizophrenia research have construed the notion of continuity (1) as subclinical defect (or forme fruste of disease) having varying expression or (2) as biologically based personality dimensions that simultaneously describe the dispositions to aberrations of function leading to degree of illness. It is noted that the model of continuity chosen can significantly shape the way the results of risk research are interpreted and the theories of psychosis to which they give rise.
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PMID:Single indicator of risk for schizophrenia: probable fact or likely myth? 819 12

Abnormalities of information processing have played a central role in understanding schizophrenia since the time of Kraepelin and Bleuler. Clearly, schizophrenia spectrum patients have profound problems focusing attention on salient cues and overcoming the disrupting effects of distracting stimuli. Theoretically, such patients are rendered vulnerable to stimulus inundation, cognitive fragmentation, and thought disorder induced by this inability to adequately process self-generated cognitive cues and stimuli from the complex world that surrounds us. Adding to the strength of such theories, investigators have made considerable progress in clarifying the functional significance and neurobiological basis of information-processing/attentional dysfunctions. This article focuses on our understanding of information-processing/attentional dysfunctions in schizophrenia. The relevant material will be presented in four parts: (1) an overview; (2) a review of specific, conceptual issues in information-processing research of the group of schizophrenias, including the roles of antipsychotic medications and generalized versus specific deficits; (3) a review of 10 common techniques used to tap the information processing and attention dysfunctions of schizophrenia patients; recent advances and novel applications of these techniques in "boundary" populations such as high-risk children and schizotypal patients are discussed and psychopharmacological probes, animal models, and basic strategies are also reviewed; and (4) an integration and suggestions for future directions in information-processing/attention research in schizophrenia. Overall, information-processing research provides an important viewpoint from which we can understand the group of schizophrenias.
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PMID:Information processing and attention dysfunctions in schizophrenia. 832 34

The N2 component of the auditory event-related potential (ERP) indexes cognitive processes involved in the categorization of deviant stimuli. Although N2 amplitude and latency abnormalities have been reported in schizophrenia, their relationship to MRI structural changes, clinical status, and P3 abnormalities has not been defined. We therefore studied the auditory N2 and P3 components elicited by an oddball paradigm in 15 right-handed male subjects with schizophrenia and 14 control subjects who had quantitative MRI measures of temporal lobe gray-matter structures. To provide a methodological comparison, we measured the auditory N2 from both the target ERP (N2t) and the target-minus-frequent ERP difference (N2d) waveforms. Both N2t and N2d amplitude were bilaterally reduced in schizophrenics, with N2d showing a more pronounced reduction. Within the schizophrenic group, N2 amplitude reduction was associated with reduction in gray-matter volume of the left superior temporal gyrus (STG) and of medial temporal lobe structures bilaterally, and clinically, with greater chronicity. P3 amplitude, in contrast, correlated only with left posterior STG volume, and was more prominently associated with delusions and thought disorder. These findings suggest that the N2 and P3 components, though occurring sequentially in the ERP, tap separable anatomic and behavioral abnormalities in schizophrenia.
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PMID:The auditory N2 component in schizophrenia: relationship to MRI temporal lobe gray matter and to other ERP abnormalities. 837 37

Scores on the Minnesota Multiphasic Personality Inventory (MMPI)-168 item version were examined during periods of clinical remission and of psychosis for recent-onset schizophrenia patients (n = 19) and at comparable time intervals for demographically matched normal participants (n = 19). To determine diagnostic specificity, MMPIs for participants with bipolar affective disorder in remission (n = 12) were also examined. Methods for distinguishing between stable vulnerability indicators, mediating vulnerability factors and episode indicators of psychopathology were adapted from Nuechterlein and Dawson (1984). MMPI scales Pa, Sc and validity scale F showed a combination of trait and state qualities, characteristic of mediating vulnerability factors. These scales reflect changes that occur during psychotic episodes but also apparently tap personality characteristics that endure into periods of clinical remission. Unexpectedly, some MMPI scales that are not typically associated with psychotic disorders (i.e. Hs, D, and Hy) were significantly higher in schizophrenia patients across psychotic and clinically remitted states than in normal participants. In clinical remission, higher scores on scales Hs, D and Hy, showed some specificity to schizophrenia relative to bipolar disorder. While MMPI-168 scales Pd and Pt fit the pattern for vulnerability indicators, it was uncertain whether they belonged to the 'stable' versus 'mediating' subtype. MMPI scores that continue to be higher in remission than in a normal sample may reflect either enduring vulnerability factors or the impact of schizophrenia and the individuals' attempts to cope with the disorder. Studies of first-degree relatives will be needed to provide converging evidence that certain personality characteristics reflect genetic predisposition to schizophrenia.
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PMID:Trait versus state aspects of the MMPI during the early course of schizophrenia. 1036 94

Traditionally, the diagnosis of schizophrenia has depended on the presence of specific behavioral phenomena assessed by way of behavioral observation and patient symptomatic report. Even though the introduction of explicit diagnostic criteria and structured interviews has improved the reliability of schizophrenia diagnosis, it is still unclear how best to define schizophrenia in order to further etiologic research. This situation persists despite ample evidence that schizophrenia is a heritable brain disorder and the existence of laboratory measures that tap into this neurobiological genetic diathesis. We contend that such laboratory measures can be used to supplement traditional clinical assessment in order to improve the definition of schizophrenia, thereby enhancing research into schizophrenia's origins. Ultimately, this increased understanding of the disorder's etiology should facilitate the development of targeted therapeutic interventions.
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PMID:At issue: assessment of schizophrenia: getting closer to the cause. 1460 36

Schizophrenic patients consistently demonstrate performance deficits on visual masking procedures. In visual masking, the subject's ability to process a target stimulus is reduced by another stimulus (mask) presented either before (forward masking) or after (backward masking) the target. Masking procedures employed in schizophrenia research have used several experimental paradigms. Most early studies have used high-energy masks (i.e., the mask is stronger than the target) and spatially overlapping target and mask. More recently, studies have begun to employ relatively weak (i.e., low-energy) masks, as well as masks that surround, but do not spatially overlap, the target. Data for forward and backward masking components of four masking conditions (target location and identification with a high-energy mask, target identification with a low-energy mask, and target identification with equal energy paracontrast/metacontrast) were collected from 75 patients with schizophrenia. Based on theoretical distinctions among masking procedures, we compared four models of visual masking using structural equation modeling. Although high zero-order correlations were found among the masking parameters, a four-factor model, in which factors were separated on the type of response (target location and identification), the shape of the function (monotonic and non-monotonic), and the overlap of the stimuli (overlapping and non-overlapping), provided the best fit for the data. These findings suggest that the four masking procedures used in this study may tap unique aspects of visual processing and are not redundant. The results also support theories of the different mechanisms underlying performance on these measures.
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PMID:Visual processing in schizophrenia: Structural equation modeling of visual masking performance. 1597 68

Given the pervasive nature of executive deficit, assessment of executive functions is of crucial importance in neuropsychiatry, child and adolescent psychiatry, geriatric psychiatry, and other related areas. A number of neuropsychologic tests of executive function commonly are used in assessing several clinical disorders, including but not limited to traumatic brain injury, schizophrenia, depression, attention deficit disorder/attention deficit hyperactivity disorder, and dementia. Because the concept of executive control in its current form constitutes an over arching construct, a construct that is based on the cognitive symptoms of the frontal lobe disorder caused by many disparate underlying conditions, no single measure of executive function can adequately tap the construct in its entirety.Therefore, it is necessary to administer several tests of executive function,each assessing a particular aspect of the executive function. An appropriate combination of such neuropsychologic tests and batteries, including the Wisconsin Card Sorting Test, Tower test, Stroop test, the D-KEFS, and the ECB, provides an adequate but relatively crude mechanism for assessing executive systems dysfunction. Neuroscientists continue to refine their understanding of the nature of executive control, and additional innovative procedures that reflect state-of-the-art insights of cognitive neuroscience have been introduced recently. Among a few first steps in that direction are nonveridical, actor-centered procedures such as the CBT and the Iowa Gambling Test.
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PMID:Neuropsychologic assessment of frontal lobe dysfunction. 1612 67

Men and women who develop schizophrenia are at increased risk, compared with the general population, to engage in violence toward others. The reasons for this robust finding remain obscure. We undertook a review of studies comparing neuropsychological test performance, neurological soft signs, and structural brain images of persons with schizophrenia with and without a history of violence. Our search identified 17 studies. The results are inconsistent and contradictory, mainly due to varying definitions of violence, differences in sample characteristics, and the use of diverse measures to tap the neurobiological correlates of violent behavior. The results suggest, however, that among men with schizophrenia, those who have displayed a stable pattern of antisocial and aggressive behavior since childhood, as compared with those with no such history, perform better on neuropsychological tests tapping specific executive functions and more poorly on assessments of orbitofrontal functions, show fewer neurological soft signs, and display larger reductions in volume of the amygdalae, more structural abnormalities of the orbitofrontal system, more abnormalities of white matter in the amygdala-orbitofrontal system, and smaller reductions in volumes of the hippocampus.
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PMID:Neurobiological correlates of violent behavior among persons with schizophrenia. 1638 76

To date, every published study of the antisaccade task has replicated the finding that schizophrenia patients make an increased number of errors. This finding has been interpreted as support for frontal and/or basal ganglia dysfunction in schizophrenia, primarily because neurological patients with pathology in these brain regions also make large numbers of errors on the antisaccade task. Here, we compared the performance of schizophrenia patients and nonpsychiatric controls on an antisaccade task and on two neuropsychological tests, the Wisconsin Card Sorting Test, which is assumed to tap frontal lobe functioning, and the interference condition of the Stroop Test, which is thought to tap dorsolateral prefrontal cortex/anterior cingulate functioning. We examined the pattern of intercorrelations among these tasks. Schizophrenia patients made significantly more errors on the antisaccade task, made more perseverative errors and achieved fewer categories on the Wisconsin Card Sorting Test, and were significantly slower during the interference condition of the Stroop Test than were nonpsychiatric controls. Antisaccade errors were significantly correlated with interference performance on the Stroop in schizophrenia patients and in controls, but were not significantly correlated with the measures of Wisconsin Card Sorting Test performance in either group. The pattern of intercorrelation suggests that these tasks should not be thought of as representing a unitary variable of "frontal cortical integrity". Although aspects of these tasks tap the ability to inhibit prepotent responses, each task is also behaviorally complex. The multifaceted nature of these tasks makes it difficult to isolate which brain regions are part of the network underlying the specific act of inhibiting a prepotent response (for example, the reflexive saccade toward the novel peripheral target) and which regions participate in aspects of task performance that are related to non-inhibitory components (for example, executing an antisaccade). A broadly distributed network is undoubtedly involved in both processes. Parsing the various components of cognitively complex tasks may help to clarify both the specific behaviors that are anomalous and their underlying neural substrates. We also address the complexity of inferring localized brain dysfunction in schizophrenia patients based on seemingly analogous behavioral deficits in neurological populations.
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PMID:The antisaccade task and neuropsychological tests of prefrontal cortical integrity in schizophrenia: empirical findings and interpretative considerations. 1663 52

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