摘要:

BackgroundDespite advances in the pharmacologic treatment of schizophrenia, the neuro-physiologic mechanism(s) of disordered attention in schizophrenia remain elusive.ObjectiveThe goal of the present study was to assess specific components of attention, including disengagement, movement, re-engagement, and the inhibitory processes involved their control.MethodsThirteen chronic schizophrenics from the inpatient and outpatient units of the Veterans Administration Medical Center (New Orleans, LA) and thirteen normal control subjects were administered a saccadic eye movements task. Saccade latency was measured in the presence of contra-lateral distracter stimuli that preceded the target onset (Distracter-before), followed the target onset (Distracter-after) or in the absence of a distracter (No-distracter). In order to assess the interactive process of fixation disengagement and target selection, fixation was either offset before the target (Gap) or it remained on in the presence of the target (Overlap).ResultsRepeated measures analysis of variance revealed that saccadic latency in patients with schizophrenia is prolonged to a greater extent than in normal control subjects in the presence of distracter stimuli. Patients with schizophrenia are also characterized by a greater percentage of error saccades directed to the distracter, and require a longer latency to “issue” corrective saccades following error saccades.ConclusionsThe findings suggest that patients with schizophrenia are required to invoke volitional control under distracter conditions, whereas normal control subjects require minimal volitional control. The results are interpreted in terms of the inhibitory mechanisms that regulate attention.

ISSN:0894-878X    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundEarly information processing deficits are consistently reported for patients with schizophrenia on smooth pursuit tracking tasks. A growing number of studies have applied a transient (magnocellular) or sustained (parvocellular) explanation to account for deficient processing of briefly presented visual stimuli, moving stimuli, and particularly, stimuli requiring smooth tracking eye movements in patients with schizophrenia.ObjectiveAlthough the preponderance of findings offer support for transient (where is it?) as opposed to sustained (what is it?) deficit, a need remains for specific depiction of the deficit. This was accomplished by applying a unique analytic method to a smooth pursuit tracking task.MethodsFourteen patients with schizophrenia and fifteen normal control subjects were tested on smooth pursuit tracking performance at five different “within-wave” dot velocity frequencies that ranged from .3 to 1.1 hz. Performance data was extracted from each of the five frequencies and then separated into 12 discrete components that corresponded to light velocity (i.e., 12 bins).ResultsA repeated measures multivariate analysis of covariance indicated that the performance of patients with schizophrenia was significantly poorer than that of their normal counterparts for three separate analyses of the time in smooth pursuit, F(11,594) = 8.99;p<0.00001, percentage of time in smooth pursuit, F(11,594) = 3.06;p<0.0005, and time in saccade eye movement, F(l 1,594) = 3.11;p<0.0004. A regression analysis revealed that the medication dosage was not significantly associated with performance on any of the critical measures, although trends were observed.ConclusionsThe findings provide support for an early information processing deficit in patients with schizophrenia. In addition, the results support the current neurophysiologic model for abnormal smooth pursuit tracking in patients with schizophrenia, specifically implicating a transient channel deficiency.

ISSN:0894-878X    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveThe aim of this study is to equalize the influence of age-related changes and to test the hypothesis that specific structural brain changes are mediating the development of unique clinical features in late-onset paranoid psychosis (LOPP).BackgroundFindings of unique white matter lesions have been recently described in patients with LOPP. These findings have not been consistent, however, when age-matched normal subjects have been used as a control group.MethodMagnetic resonance imaging data were compared in 13 patients with LOPP, mean age 66.33, and 35 elderly patients with early-onset paranoid schizophrenia (PSCH), mean age 63.89. Patients in the LOPP group differed from the PSCH group by the mild degree or absence of negative symptoms, the absence of formal thought disorders, and by prevalence of female patients.ResultsAnalysis of the magnetic resonance imaging data revealed statistically significant differences between the LOPP and PSCH groups. White matter hyperintensity was almost threefold more frequent in LOPP than in PSCH groups, 69.2% versus 22.9% respectively. Ventricular enlargement and cortical atrophy were more frequent in the PSCH group, reaching, for moderate to severe abnormalities, 28.6% for ventricular enlargement and 22.9% for cortical atrophy; moderate to severe abnormalities were absent in all 13 patients of the LOPP group.ConclusionsThese data point to the possibility that late-onset paranoid psychosis is a distinct clinicopathological entity, with white matter hyperintensity mediating the development of LOPP in a significant percentage of the cases. The vascular origin of white matter lesions in LOPP is suggested.

ISSN:0894-878X    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveThis study analyzes lesion configuration in patients in the post-acute stage after first single unilateral stroke who suffered from depressive disorders.BackgroundRecent studies indicate a biological origin of poststroke depressive disorders. Due to differences in times of investigation, methods applied, and patient selection, most data are not comparable. Furthermore, only a few studies of poststroke depression report detailed neuropsychologic assessments.MethodsWe investigated 20 consecutive patients who were diagnosed as depressive according to DSM-III-R criteria and exhibited no other severe illness, had no history of neurologic or psychiatric disease, and who were either not aphasic, or only mildly aphasic. A structured clinical interview, self-based and observer-based depression rating scales, a comprehensive neuropsychologic and neurologic examination and ADL-measurement were applied. Neuroradiologic analysis was based on standardized computed tomography scans.ResultsNine of 10 subjects with left hemisphere strokes exhibited a major depression and 7 of 10 subjects with right hemisphere infarcts a minor depression. The most prominent neuropsychologic deficits were found in frontal lobe associated tasks. Type and severity of depression were not related to the severity of neurologic symptoms or impairment in activities of daily living. For both major and minor depression the maximal overlap of lesions was found in subcortical areas, including parts of the caudate nucleus, posterior parts of the putamen, and the deep white matter.ConclusionsThe findings support the theory that poststroke depression is related to the dysfunction of (cortico-) striato-pallido-thalamic-cortical projections that modulate cortico-thalamo-cortical loop systems.

ISSN:0894-878X    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveTo examine for structural asymmetries in the posterior superior temporal lobe at the microscopic level in an effort to explain the gross anatomical and functional asymmetries of this brain region.BackgroundThe posterior superior temporal lobe is typically larger on the left and damage to this area frequently results in an aphasia. This has led to the hypothesis that the structural asymmetry determines the functional asymmetry, but no definite confirmation of this hypothesis exists.MethodsSixteen men were studied at postmortem. Posterior superior temporal lobe dimensions, gray matter volume, white matter volume, SMI-32 immunopositive neuronal density, and glia cell volume were measured for both the left and right hemispheres. In a subset of eight subjects, myelin sheath and axon diameters were measured with electron microscopy.ResultsPosterior superior temporal lobe white matter volume was greater on the left (p= 0.003,ttest for dependent samples). This asymmetry did not appear to be the result of an isolated proliferation of glia (p= 0.46,ttest for dependent samples), nor the density of cortical to cortical projections neurons in the overlying cortex (p= 0.71,ttest for dependent samples). In a subset of eight subjects studied with electron microscopy, axons of the left posterior superior temporal lobe were more thickly myelinated (57 nm [SD = 27] left, 46 nm [SD = 24],p< 0.001, ANOVA).ConclusionsAs axons with thicker myelin sheaths conduct faster and require a greater volume, these results suggest asymmetry of myelination as an explanation for both a left hemisphere dominance for rapid sensory signal processing, leading to a functional asymmetry for language, and a larger left planum temporale.

ISSN:0894-878X    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveThis study examined lexical emotional perception in patients with unilateral brain damage.BackgroundHypotheses pertaining to laterality and emotion were tested. More specifically, we were interested in whether the right hemisphere is dominant for verbally-presented emotion. In addition, we examined whether emotional content improves the performance of patients with left brain damage (LBD) and language deficits.MethodSubjects were 11 patients with right brain damage (RBD), 10 patients with LBD, and 15 normal control adults. The subject groups did not differ significantly on demographic or basic cognitive variables; the patient groups were similar on neurologic variables. Parallel emotional experimental and nonemotional control tasks included word identification (or recognition), sentence identification, and word discrimination. There were eight emotional categories (e.g., happiness) and eight nonemotional categories (e.g., vision).ResultsA significant interaction among Group, Condition, and Task revealed that patients with RBD were significantly impaired relative to patients with LBD and normals within the emotional condition, particularly for the identification tasks. Furthermore, the performance of patients with LBD and language deficits was improved by emotional content for the sentence identification task.ConclusionsThese findings suggest that the right hemisphere has a unique contribution in the identification of lexical emotional stimuli. Implications for rehabilitation of patients with LBD and language deficits and patients with RBD by means of emotion-based strategies are discussed.

ISSN:0894-878X    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveTo examine the differential impairment of implicit and explicit memory systems in cortical and subcortical dementias.BackgroundWhereas verbal priming was reported to be impaired in patients with Alzheimer Disease (AD), patients with Parkinson Disease (PD) may be relatively more impaired on tasks of motor skill learning.MethodsWe examined 15 patients with Alzheimer disease, 10 patients with Parkinson disease and dementia (PD-D), 15 patients with PD but no dementia, and 24 age-comparable normal control subjects with a neuropsychologic battery that included tests of explicit memory (Buschke Selective Reminding Test, Benton Visual Retention Test, Digits Span), and tests of implicit memory (Word-Stem Completion task and the Maze Test).ResultsAD and PD-D groups showed similar deficits on all measures of explicit memory, and performed significantly worse than PD patients without dementia and normal control subjects. On the other hand, there were no significant between-group differences in any of the measures of implicit memory.ConclusionsOur study demonstrated preserved implicit learning in the context of severe explicit learning deficits in patients with dementia, but could not demonstrate a different profile of memory deficits between so-called cortical and subcortical dementias.

ISSN:0894-878X    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveTo examine the concurrent validity of a newly developed telephone adaptation of the Modified Mini-Mental State Exam.BackgroundLongitudinal studies of cognition may be advantaged by availability of assessment instruments that can be used over the telephone, as well as in person.MethodSubjects were 263 noninstitutionalized elderly residents of a rural community in southern Idaho, aged 65 to 93, who had little or no cognitive difficulty. At an average interval of four weeks, we administered the Modified Mini-Mental State Exam (3MS) and the newly adapted Telephone Modified Mini-Mental State Exam (T3MS). Order of administration was randomly assigned.ResultsAgreement between scores on the two instruments was good (r= 0.82,p< 0.001). When we applied various cutoff scores to the instruments, thereby generating assignments of individuals to “screen positive” and “screen negative” groups, the percent agreement in screening results ranged from 80% to 96% as we reduced the cutoff scores from 90 to 74 (100 points possible).ConclusionsAt least among subjects without major cognitive syndromes, the Telephone Modified Mini-Mental State Exam provides a reasonable substitute for the more costly in-person 3MS. The telephone instrument should now be tested over a broader range of cognitive abilities in order to assess its validity in more impaired subjects, e.g., by studying an institutionalized sample.

ISSN:0894-878X    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0894-878X    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0894-878X    

出版商:OVID    

年代:1999

数据来源: OVID