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

Both simple attention tasks (e.g. letter cancellation) and most tasks of higher cognitive processing (e.g. word generation) are known to activate the dorsolateral prefrontal cortex (PFC). While attention and higher cognitive processing differ phenomenologically, with attention tasks requiring great subjective effort despite their simplicity, possible physiological differences in the activation of the PFC between the two types of cognitive processing have remained uninvestigated. Hemodynamic changes in the PFC during activation due to tasks of attention and those of higher cognitive processing were examined using near-infrared spectroscopy in 10 Japanese and 10 American healthy adults. In tasks of higher cognitive processing, which included both verbal and non-verbal tasks, the concentration of oxygenated hemoglobin ([HbO2]) increased, and that of deoxygenated hemoglobin ([HbR]) decreased, with an increase in the tissue hemoglobin saturation (THS). In tasks of attention, which consisted of the letter cancellation and continuous performance test, both [HbO2] and [HbR] increased, with no significant changes in the THS observed. The distinctive patterns of hemodynamic changes were not affected by the factors of task difficulty or language. The change in [HbR] may be a physiological marker of the prefrontal lobe activation that discriminates between attention and higher cognitive processing. The increase in [HbR] suggests increased oxygen consumption of the PFC during tasks of attention, which might be related to the disproportionately great subjective effort associated with sustained attention. The physiological alteration in hemodynamic patterns according to changes in cognition needs to be examined in subjects with prefrontal lobe dysfunction, such as schizophrenia and mood disorder.
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PMID:Hemodynamic differences in the activation of the prefrontal cortex: attention vs. higher cognitive processing. 1472 6

We assessed the cerebral hemoglobin oxygenation response in the left frontal area in 62 schizophrenia patients and 31 healthy subjects during a verbal fluency test (VF) and letter number span test (LN) measured by near-infrared spectroscopy (NIRS). Oxygenated hemoglobin (oxyHb) increased during VF and LN in both groups. Schizophrenia patients showed lower VF and LN performance and a smaller increase in oxyHb during VF than controls. A reduced oxyHb response during VF in schizophrenia patients was also observed even when their VF performance was matched with controls' performance. On the other hand, increase in oxyHb during LN in schizophrenia patients was comparable with that in controls. In addition, patients medicated with atypical antipsychotics showed a larger increase in oxyHb during VF and LN than those medicated with typical antipsychotics. The present study confirmed functional hypofrontality in schizophrenia patients reported by other modalities such as position emission tomography, single-photon emission tomography, and functional magnetic resonance imaging and suggested that the hypofrontality may be task dependent.
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PMID:Cerebrovascular response to cognitive tasks in patients with schizophrenia measured by near-infrared spectroscopy. 1527 58

Using transmission electron microscopy, erythrocyte ultrastructure in norm and pathology was described. Among the morphological phenomena, most common were local and extensive erythrocyte plasmalemmal defects in the form of its loosening, thinning, consolidation and thickening, rupture, fragmentation, exfoliation from stroma with the formation of cavities. Plasmalemmal destruction may be accompanied with the formation of micro- and macroexovesicles, some of which lose the connection with the erythrocyte. Morphological signs of erythrocyte stromal disorganization included irregular distribution of hemoglobin granules with the formation of the regions of increased and decreased electron density, loosening of the internal structure up to the formation of cavities, as well as endovesicles, partially containing small or large osmiophilic particles. It was shown that in pathological processes of different genesis (malignant tumors, chronic bronchitis, burn trauma, schizophrenia) ultrastructural changes of erythrocytes have typical character.
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PMID:[Erythrocyte ultrastructure in norm and pathology: morphological phenomena and clinical correlations]. 1584 97

Letter- or semantically-cued verbal fluency tests (VFT) induce different, but overlapping activities in the prefrontal cortex (PFC) in healthy subjects. Functional differences between letter and semantic VFT may be important in elucidating the nature of language-related problems in schizophrenia since more profound impairment in semantically-cued retrieval may be suggestive of semantic system dysfunction specific to this disorder. However, the functional differences between the letter vs. semantic VFT on prefrontal metabolism in the subjects with schizophrenia have not been described. In the present study, we used near-infrared spectroscopy (NIRS) to assess hemoglobin concentration changes in the bilateral PFCs in subjects and controls. Sixteen subjects with schizophrenia and 19 healthy controls performed letter and semantic VFTs. Prefrontal hemodynamic changes were simultaneously monitored by NIRS. While healthy subjects performed both tasks equivalently, the subjects with schizophrenia showed more compromised performance in the semantic VFTs compared to the letter VFTs. NIRS measurement revealed that the pattern of PFC activation was greater during the letter VFT when compared to the semantic VFT in the healthy subjects, suggesting more prominent PFC involvement in letter-cued retrieval. In contrast, the subjects with schizophrenia showed the opposite pattern of activation, implying that the semantic mode of lexical access might impose greater cognitive demands on the PFC. The present study is the first to detect abnormal patterns of PFC activation in adults with schizophrenia in response to the distinct cognitive demands associated with letter and semantic VFT.
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PMID:Prefrontal activation during verbal fluency tests in schizophrenia--a near-infrared spectroscopy (NIRS) study. 1600 86

Hypofrontality has been a major finding obtained from functional neuroimaging studies on schizophrenia, although there have also been contradictory results that have questioned the reality of hypofrontality. In our previous study, we confirmed the existence of activation hypofrontality by using a 2-channel continuous-wave-type (CW-type) near-infrared spectroscopy (NIRS) instrument. In this study, we employed a single-channel time-resolved spectroscopy (TRS) instrument, which can quantify hemoglobin (Hb) concentrations based on the photon diffusion theory, to investigate resting hypofrontality. A pair of incident and detecting light guides was placed on either side of the forehead at approximately Fp2-F8 or Fp1-F7 alternately in 14 male schizophrenic patients and 16 age-matched male control subjects to measure Hb concentrations at rest. The patients were also measured with a 2-channel CW-type NIRS instrument during the performance of a random number generation (RNG) task. A reduced total hemoglobin concentration (t-Hb) less than 60 microM (the mean value of the control subjects-1.5 SD) was observed bilaterally in 4 patients and only in the left side in 3 patients. Activation hypofrontality was more manifest in these patients than in the remaining 7 patients despite the same task performance. This decreased t-Hb was related to the duration of illness, and it was not observed in patients whose duration of illness was less than 10 years. These results indicate that resting hypofrontality is a chronically developed feature of schizophrenia. This does not necessarily represent frontal dysfunction, but may reflect anatomical and/or functional changes in frontal microcirculation.
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PMID:Resting hypofrontality in schizophrenia: A study using near-infrared time-resolved spectroscopy. 1662 44

Risperidone has a relatively low risk of causing obesity and diabetes mellitus and is a first-line treatment for schizophrenia. The aim of the present study was to investigate glucose and lipid metabolism, and feeding-control parameters in schizophrenia patients treated with long-term risperidone monotherapy. Fifteen patients with paranoid-type schizophrenia who had been treated with risperidone and had Global Assessment of Function (GAF) scores >70 were selected and compared with healthy volunteers (n = 25). Single assessments of psychotic symptoms, side-effects, Drug-Induced Extrapyramidal Symptoms Scale (DIEPSS) score, bodyweight, body fat percentage and blood sampling were performed. Fasting blood glucose, insulin, hemoglobin A1c, homeostasis model assessment insulin resistance index (HOMA-IR), total cholesterol, triglyceride, high density lipoprotein (HDL)-, low density lipoprotein-cholesterol, adiponectin, prolactin and feeding-control parameters (ghrelin and leptin) were analyzed. The body fat percentage (P = 0.0018), body mass index (BMI) (P = 0.0150), fasting blood glucose (P = 0.0358), triglyceride (P = 0.0377), leptin (P = 0.0243), total ghrelin (P = 0.0067), active ghrelin (P = 0.0241) and prolactin (P < 0.0001) levels of patients treated with risperidone were significantly higher than those of healthy volunteers, while the HDL-cholesterol level (P = 0.0222) was significantly lower. Although the patients had very mild psychiatric symptoms and maintained functionally high levels, the glucose and lipid parameters were significantly impaired compared to healthy volunteers. A high level of plasma ghrelin might increase appetite, leading to exacerbation of metabolic impairment.
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PMID:Glucose and lipid metabolism of long-term risperidone monotherapy in patients with schizophrenia. 1723 39

The purpose of this study was to examine the prevalence and correlates of religious participation among persons with co-occurring serious mental illness and type 2 diabetes. Among 201 outpatients, 53% attended religious services, 36% had regular contact with a religious leader, and 15% received assistance from a religious leader. Persons with schizophrenia and African Americans were more likely to attend services and have contact with religious leaders. Both attendance at religious services and regular contact with a religious leader were linked to higher quality of life in selected domains, but not associated with global health ratings or glycosylated hemoglobin (HbA1c) levels. Results indicate that there are important diagnostic and racial differences in religious participation, and that religious participation may be a resilience factor that supports enhanced quality of life for persons with serious mental illness and diabetes.
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PMID:Correlates of religious service attendance and contact with religious leaders among persons with co-occurring serious mental illness and type 2 diabetes. 1750 3

Functional neuroimaging studies to date have shown prefrontal dysfunction during executive tasks in schizophrenia. However, relationships between hemodynamic response in prefrontal sub-regions and clinical characteristics have been unclear. The objective of this study is to evaluate prefrontal hemodynamic response related to an executive task in schizophrenia and to assess the relationship between activation in the prefrontal sub-regions and clinical status. Fifty-five subjects with schizophrenia and age- and gender-matched 70 healthy subjects were recruited for this case-control study in a medical school affiliated hospital in the Tokyo metropolitan area, Japan. We measured hemoglobin concentration changes in the prefrontal (dorsolateral, ventrolateral, and frontopolar regions) and superior temporal cortical surface area during verbal fluency test using 52-channel near-infrared spectroscopy, which enables real-time monitoring of cerebral blood volumes in the cortical surface area under a more restraint-free environment than positron emission tomography or functional magnetic resonance imaging. The two groups showed distinct spatiotemporal pattern of oxy-hemoglobin concentration change during verbal fluency test. Schizophrenia patients were associated with slower and reduced increase in prefrontal activation than healthy controls. In particular, reduced activations of the frontopolar region, rather than lateral prefrontal or superior temporal regions, showed significant positive correlations with lower global assessment of functioning scores in the patient group, although task performance was not significantly associated with the scores. These results suggest that reduced frontopolar cortical activation is associated with functional impairment in patients with schizophrenia and that near-infrared spectroscopy may be an efficient clinical tool for monitoring these characteristics.
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PMID:Reduced frontopolar activation during verbal fluency task in schizophrenia: a multi-channel near-infrared spectroscopy study. 1806 44

Abnormal prefrontal functioning plays a central role in the working memory (WM) deficits of schizophrenic patients, but the nature of the relationship between WM and prefrontal activation remains undetermined. Using two functional neuroimaging methods, we investigated the neural correlates of remembering and forgetting in schizophrenic and healthy participants. We focused on the brain activation during WM maintenance phase with event-related functional magnetic resonance imaging (fMRI). We also examined oxygenated hemoglobin changes in relation to memory performance with the near-infrared spectroscopy (NIRS) using the same spatial WM task. Distinct types of correct and error trials were segregated for analysis. fMRI data indicated that prefrontal activation was increased during WM maintenance on correct trials in both schizophrenic and healthy subjects. However, a significant difference was observed in the functional asymmetry of frontal activation pattern. Healthy subjects showed increased activation in the right frontal, temporal and cingulate regions. Schizophrenic patients showed greater activation compared with control subjects in left frontal, temporal and parietal regions as well as in right frontal regions. We also observed increased 'false memory' errors in schizophrenic patients, associated with increased prefrontal activation and resembling the activation pattern observed on the correct trials. NIRS data replicated the fMRI results. Thus, increased frontal activity was correlated with the accuracy of WM in both healthy control and schizophrenic participants. The major difference between the two groups concerned functional asymmetry; healthy subjects recruited right frontal regions during spatial WM maintenance whereas schizophrenic subjects recruited a wider network in both hemispheres to achieve the same level of memory performance. Increased "false memory" errors and accompanying bilateral prefrontal activation in schizophrenia suggest that the etiology of memory errors must be considered when comparing group performances. Finally, the concordance of fMRI and NIRS data supports NIRS as an alternative functional neuroimaging method for psychiatric research.
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PMID:Origins of spatial working memory deficits in schizophrenia: an event-related FMRI and near-infrared spectroscopy study. 1833 36

In schizophrenia, dysfunction of the prefrontal cortex (PFC), regarded as a core feature of the disease, has been investigated by different neuroimaging methods. Near infrared spectroscopy (NIRS), a novel neurophysiological method, is being increasingly used in the investigation of frontal dysfunction in schizophrenia. However, NIRS measurements during multiple frontal activation tasks have been rarely reported. The purpose of this study was to compare hemodynamic changes in the PFC between patients with schizophrenia and healthy controls during four different types of frontal lobe tasks using a 2-channel NIRS system. Thirty patients with schizophrenia and thirty age- and gender-matched healthy controls were enrolled in this study. In both groups, changes in oxygenated hemoglobin concentration (Delta[oxyHb]) at the bilateral forehead were measured during Verbal fluency test letter version (VFT-letter), VFT category version, Tower of Hanoi (TOH), the Sternberg and Stroop tasks. Regarding Delta[oxyHb] in PFC, a diagnosis group effect was found for VFT-letter and TOH. Significant negative correlation was found between left Delta[oxyHb] during TOH and negative and cognitive symptom scores in schizophrenia patients. Right Delta[oxyHb] during TOH also showed significant negative correlation with cognitive symptoms scores. No significant correlation between Delta[oxyHb] and clinical characteristics were observed during VFT-letter. These findings suggest that among a battery of frontal lobe tasks administered to schizophrenia patients, VFT-letter and TOH are more sensitive to detect PFC activation, as indicated by Delta[oxyHb] using a 2-channel NIRS. Taken together, these findings and those of previous neuroimaging studies suggest that VFT-letter and TOH might represent possible candidate physiological markers of prefrontal dysfunction in schizophrenia, though extensive testing in clinical settings will be necessary.
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PMID:Impaired regional hemodynamic response in schizophrenia during multiple prefrontal activation tasks: a two-channel near-infrared spectroscopy study. 1915 86


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