| 1 | Biol. Psychiatry 2004 Jan 55: 154-64 |
|---|---|
| PMID | 14732595 |
| Title | Near-infrared spectroscopy analysis of frontal lobe dysfunction in schizophrenia. |
| Abstract | Previous studies have shown that near-infrared spectroscopy (NIRS) has high temporal resolution, requires little restraint, and is suitable for examining the effect of psychological tasks on brain circulation. In the present study, frontal function in schizophrenic patients was analyzed by NIRS during random number generation (RNG), ruler-catching (RC), and sequential finger-to-thumb (SFT) tasks. Two sets of NIRS probes were attached to the foreheads of 13 schizophrenic patients and 10 control subjects approximately at Fp1-F7 and Fp2-F8. Near-infrared spectroscopy was conducted at a sampling rate of 1 Hz, with the pathlength being determined by time-resolved spectroscopy with differential pathlength factor measurements. The absolute changes in oxygenated (oxy-Hb) and deoxygenated (deoxy-Hb) hemoglobin concentrations in response to each task were measured, and total hemoglobin (total-Hb) concentration was calculated as the sum of the two. During RNG task, total- and oxy-Hb concentrations increased, and deoxy-Hb decreased, but the responses were significantly smaller in schizophrenic patients. During RC task, oxy-Hb in schizophrenic patients tended to decrease, in contrast to the mostly increasing response in control subjects. No group difference was observed during SFT task. Task-dependent profile of functional abnormalities was observed in schizophrenic frontal brain metabolism. These results support the usefulness of NIRS data in investigating frontal lobe dysfunction and evaluating psychopathologic condition in schizophrenic patients. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 2 | Biol. Psychiatry 2004 Jan 55: 154-64 |
| PMID | 14732595 |
| Title | Near-infrared spectroscopy analysis of frontal lobe dysfunction in schizophrenia. |
| Abstract | Previous studies have shown that near-infrared spectroscopy (NIRS) has high temporal resolution, requires little restraint, and is suitable for examining the effect of psychological tasks on brain circulation. In the present study, frontal function in schizophrenic patients was analyzed by NIRS during random number generation (RNG), ruler-catching (RC), and sequential finger-to-thumb (SFT) tasks. Two sets of NIRS probes were attached to the foreheads of 13 schizophrenic patients and 10 control subjects approximately at Fp1-F7 and Fp2-F8. Near-infrared spectroscopy was conducted at a sampling rate of 1 Hz, with the pathlength being determined by time-resolved spectroscopy with differential pathlength factor measurements. The absolute changes in oxygenated (oxy-Hb) and deoxygenated (deoxy-Hb) hemoglobin concentrations in response to each task were measured, and total hemoglobin (total-Hb) concentration was calculated as the sum of the two. During RNG task, total- and oxy-Hb concentrations increased, and deoxy-Hb decreased, but the responses were significantly smaller in schizophrenic patients. During RC task, oxy-Hb in schizophrenic patients tended to decrease, in contrast to the mostly increasing response in control subjects. No group difference was observed during SFT task. Task-dependent profile of functional abnormalities was observed in schizophrenic frontal brain metabolism. These results support the usefulness of NIRS data in investigating frontal lobe dysfunction and evaluating psychopathologic condition in schizophrenic patients. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 3 | Schizophr. Res. 2006 Jun 84: 411-20 |
| PMID | 16626944 |
| Title | Resting hypofrontality in schizophrenia: A study using near-infrared time-resolved spectroscopy. |
| Abstract | 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. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 4 | Schizophr. Res. 2006 Jun 84: 411-20 |
| PMID | 16626944 |
| Title | Resting hypofrontality in schizophrenia: A study using near-infrared time-resolved spectroscopy. |
| Abstract | 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. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 5 | Psychiatry Res 2007 Jan 149: 41-7 |
| PMID | 17140670 |
| Title | State-dependent changes in intrahemispheric EEG coherence for patients with acute exacerbation of schizophrenia. |
| Abstract | Abnormalities of electroencephalographic (EEG) coherence in schizophrenia are thought to reflect functional disconnections between different brain regions associated with the onset of this disease. To clarify whether these abnormalities change in a symptom-dependent manner in individual patients, we analyzed the coherence of resting EEGs recorded at two time points with a 36.6-day interval during the course of treatment for 14 patients who had been hospitalized for acute exacerbation of schizophrenia. Symptom severity was quantitatively measured by means of the Brief Psychiatric Rating Scale (BPRS). Beta (13-20 Hz) coherence for the left frontal (F7)-temporal (T5) electrode pair was less than that for the corresponding right pair (F8-T6) at the initial test. At the second test, when symptoms had improved, the left frontal-temporal beta coherence had increased, resulting in disappearance of the laterality. This change in beta coherence for the left frontal-temporal pair correlated negatively with the change in the total BPRS score, particularly the positive symptom score. Similar correlations were found for eight patients who had been drug-free at the first examination. These results suggest that a functional disconnection between the frontal and the temporal lobe in the left hemisphere may be associated with the generation of acute psychotic symptoms in schizophrenia. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 6 | Clin Neurophysiol 2008 Jun 119: 1232-41 |
| PMID | 18396454 |
| Title | Abnormal EEG complexity in patients with schizophrenia and depression. |
| Abstract | schizophrenics are usually unable to perform well on cognitive tasks due to disturbances in cortical information processing that are observable as abnormalities in electroencephalogram (EEG) signals. However, whether such cortical disturbances can be assessed by quantitative EEG analysis remains unclear. The purpose of this study was to characterize EEG disturbances, using the Lempel-Ziv complexity (LZC), in the subjects with schizophrenia at rest or while performing mental arithmetic tasks. The results were compared to those from the subjects with depression and with healthy controls. The subjects included 62 schizophrenia patients, 48 depression patients and 26 age-matched healthy controls. EEG was recorded under two conditions: (i) resting with eyes closed, and (ii) a mentally active condition wherein the subjects were asked to subtract 7 from 100 iteratively with their eyes closed. EEG signals were analyzed by LZC and conventional spectral methods. In all the groups, LZC of EEG decreased during the mental arithmetic compared with those under the resting conditions. Both the schizophrenia and the depression groups had a higher LZC (p<0.05) than the controls. Also, the schizophrenia group had a lower LZC (p<0.05) than the depression group during the mental arithmetic task as well as during the resting state. Significant differences in LZC, at some symmetrically located loci (FP1/FP2, F7/F8), between the two hemispheres were found in all the patient groups only during the arithmetic task. Compared with conventional spectral analysis, LZC was more sensitive to both the power spectrum and the temporal amplitude distribution. LZC was associated with the ability to attend to the task and adapt the information processing system to the cognitive challenge. Thus, it would be useful in studying the disturbances in the cortical information processing patients with depression or schizophrenia. LZC of EEG is associated with mental activity. Thus, LZC analysis can be an important tool in understanding the pathophysiology of schizophrenia and depression in future studies. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 7 | Clin Neurophysiol 2008 Jun 119: 1232-41 |
| PMID | 18396454 |
| Title | Abnormal EEG complexity in patients with schizophrenia and depression. |
| Abstract | schizophrenics are usually unable to perform well on cognitive tasks due to disturbances in cortical information processing that are observable as abnormalities in electroencephalogram (EEG) signals. However, whether such cortical disturbances can be assessed by quantitative EEG analysis remains unclear. The purpose of this study was to characterize EEG disturbances, using the Lempel-Ziv complexity (LZC), in the subjects with schizophrenia at rest or while performing mental arithmetic tasks. The results were compared to those from the subjects with depression and with healthy controls. The subjects included 62 schizophrenia patients, 48 depression patients and 26 age-matched healthy controls. EEG was recorded under two conditions: (i) resting with eyes closed, and (ii) a mentally active condition wherein the subjects were asked to subtract 7 from 100 iteratively with their eyes closed. EEG signals were analyzed by LZC and conventional spectral methods. In all the groups, LZC of EEG decreased during the mental arithmetic compared with those under the resting conditions. Both the schizophrenia and the depression groups had a higher LZC (p<0.05) than the controls. Also, the schizophrenia group had a lower LZC (p<0.05) than the depression group during the mental arithmetic task as well as during the resting state. Significant differences in LZC, at some symmetrically located loci (FP1/FP2, F7/F8), between the two hemispheres were found in all the patient groups only during the arithmetic task. Compared with conventional spectral analysis, LZC was more sensitive to both the power spectrum and the temporal amplitude distribution. LZC was associated with the ability to attend to the task and adapt the information processing system to the cognitive challenge. Thus, it would be useful in studying the disturbances in the cortical information processing patients with depression or schizophrenia. LZC of EEG is associated with mental activity. Thus, LZC analysis can be an important tool in understanding the pathophysiology of schizophrenia and depression in future studies. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 8 | Psychiatr Danub 2009 Dec 21: 579-84 |
| PMID | 19935497 |
| Title | EEG characteristics in depression, "negative" and "positive" schizophrena. |
| Abstract | qEEG investigations present differences in the comparison of schizophrenic patients and healthy examinees, as well as of depressive patients and healthy controls. The comparison of "positive" and "negative" schizophrenia also presents differences in the qEEG parameters. Changes in qEEG are various in these studies, but not always consistent. In this research we wanted to compare "positive" schizophrenia, "negative" schizophrenia and depression. The sample comprised 55 examinees (all women): 20 patients with "positive" schizophrenia, 15 patients with "negative" schizophrenia and 20 patients with depression. The standard EEG registration was done in all of them. From the recorded material, the 20-second period without artifacts was analyzed by the FFT method. The results were presented as absolute special power values (muV(2)) for individual segments of the spectrum: delta (0.5-4.0), theta (4.0-8.0), alpha (8.0-13.0) and beta (13.0-30.0). The observed regions included Fp1, Fp2, F3, F4, F7, F8, T3, T4, P3, P4, O1 and O2. The "positive" type schizophrenia differs from the "negative" in the increase in both delta and theta activities, and in the decline of beta activity over frontal regions. The "positive" type of schizophrenia differs from depression in the increase in delta activity over frontal regions, while the "negative" form of schizophrenia differs from it in the decrease in beta activity over frontal regions. qEEG parameters differ in the comparison of "positive" and "negative" types of schizophrenia. These differences are more numerous and more significant than those obtained in the comparison of each of these types of schizophrenia with depression. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 9 | Psychiatr Danub 2009 Dec 21: 579-84 |
| PMID | 19935497 |
| Title | EEG characteristics in depression, "negative" and "positive" schizophrena. |
| Abstract | qEEG investigations present differences in the comparison of schizophrenic patients and healthy examinees, as well as of depressive patients and healthy controls. The comparison of "positive" and "negative" schizophrenia also presents differences in the qEEG parameters. Changes in qEEG are various in these studies, but not always consistent. In this research we wanted to compare "positive" schizophrenia, "negative" schizophrenia and depression. The sample comprised 55 examinees (all women): 20 patients with "positive" schizophrenia, 15 patients with "negative" schizophrenia and 20 patients with depression. The standard EEG registration was done in all of them. From the recorded material, the 20-second period without artifacts was analyzed by the FFT method. The results were presented as absolute special power values (muV(2)) for individual segments of the spectrum: delta (0.5-4.0), theta (4.0-8.0), alpha (8.0-13.0) and beta (13.0-30.0). The observed regions included Fp1, Fp2, F3, F4, F7, F8, T3, T4, P3, P4, O1 and O2. The "positive" type schizophrenia differs from the "negative" in the increase in both delta and theta activities, and in the decline of beta activity over frontal regions. The "positive" type of schizophrenia differs from depression in the increase in delta activity over frontal regions, while the "negative" form of schizophrenia differs from it in the decrease in beta activity over frontal regions. qEEG parameters differ in the comparison of "positive" and "negative" types of schizophrenia. These differences are more numerous and more significant than those obtained in the comparison of each of these types of schizophrenia with depression. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 10 | Schizophr. Res. 2010 Mar 117: 52-60 |
| PMID | 19896332 |
| Title | Discriminant analysis in schizophrenia and healthy subjects using prefrontal activation during frontal lobe tasks: a near-infrared spectroscopy. |
| Abstract | While psychiatric disorders such as schizophrenia are largely diagnosed on symptomatology, several studies have attempted to determine which biomarkers can discriminate schizophrenia patients from non-patients with schizophrenia. The objective of this study is to assess whether near-infrared spectroscopy (NIRS) measurement can distinguish schizophrenia patients from healthy subjects. Sixty patients with schizophrenia and sixty age- and gender-matched healthy controls were divided into two sequential groups. The concentration change in oxygenated hemoglobin (Delta[oxy-Hb]) was measured in the bilateral prefrontal areas (Fp1-F7 and Fp2-F8) during the Verbal Fluency Test (VFT) letter version and category version, Tower of Hanoi (TOH), Sternberg's (SBT) and Stroop Tasks. In the first group, schizophrenia patients showed poorer task performance on all tasks and less prefrontal cortex activation during all but the Stroop Task compared to healthy subjects. In the second group, schizophrenia patients showed poorer task performance and less prefrontal cortex activation during VFTs and TOH tasks than healthy subjects. We then performed discriminant analysis by a stepwise method using Delta[oxy-Hb] and task performance measures as independent variables. The discriminant analysis in the first group included task performance of TOH, VFT letter and VFT category and Delta[oxy-Hb] of VFT letter. As a result, 88.3% of the participants were correctly classified as being schizophrenic or healthy subjects in the first analysis. The discriminant function derived from the first group correctly assigned 75% of the subjects in the second group. Our findings suggest that NIRS measurement could be applied to differentiate patients with schizophrenia from healthy subjects. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 11 | Schizophr. Res. 2010 Mar 117: 52-60 |
| PMID | 19896332 |
| Title | Discriminant analysis in schizophrenia and healthy subjects using prefrontal activation during frontal lobe tasks: a near-infrared spectroscopy. |
| Abstract | While psychiatric disorders such as schizophrenia are largely diagnosed on symptomatology, several studies have attempted to determine which biomarkers can discriminate schizophrenia patients from non-patients with schizophrenia. The objective of this study is to assess whether near-infrared spectroscopy (NIRS) measurement can distinguish schizophrenia patients from healthy subjects. Sixty patients with schizophrenia and sixty age- and gender-matched healthy controls were divided into two sequential groups. The concentration change in oxygenated hemoglobin (Delta[oxy-Hb]) was measured in the bilateral prefrontal areas (Fp1-F7 and Fp2-F8) during the Verbal Fluency Test (VFT) letter version and category version, Tower of Hanoi (TOH), Sternberg's (SBT) and Stroop Tasks. In the first group, schizophrenia patients showed poorer task performance on all tasks and less prefrontal cortex activation during all but the Stroop Task compared to healthy subjects. In the second group, schizophrenia patients showed poorer task performance and less prefrontal cortex activation during VFTs and TOH tasks than healthy subjects. We then performed discriminant analysis by a stepwise method using Delta[oxy-Hb] and task performance measures as independent variables. The discriminant analysis in the first group included task performance of TOH, VFT letter and VFT category and Delta[oxy-Hb] of VFT letter. As a result, 88.3% of the participants were correctly classified as being schizophrenic or healthy subjects in the first analysis. The discriminant function derived from the first group correctly assigned 75% of the subjects in the second group. Our findings suggest that NIRS measurement could be applied to differentiate patients with schizophrenia from healthy subjects. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 12 | Brain Res. 2011 Mar 1377: 21-31 |
| PMID | 21195697 |
| Title | The effects of catechol-O-methyl-transferase polymorphism Val158Met on functional connectivity in healthy young females: a resting EEG study. |
| Abstract | The catechol-O-methyl-transferase (COMT) gene has been linked to a wide spectrum of human phenotypes, including cognition, affective response, pain sensitivity, anxiety and psychosis. This study examined the modulatory effects of COMT Val158Met on neural interactions, indicated by connectivity strengths. Blood samples and resting state eyes-closed EEG signals were collected in 254 healthy young females. The COMT Val158Met polymorphism was decoded into 3 groups: Val/Val, Val/Met and Met/Met. The values of mutual information of 20 frontal-related channel pairs across delta, theta, alpha and beta frequencies were analyzed based on the time-frequency mutual information method. Our one-way ANOVA analyses revealed that the significant connection-frequency pairs were relatively left lateralized (P<0.01) and included F7-T3 and F7-C3 at delta frequency, and F3-F4, F7-T3, F7-C3, F7-P3, F3-C3, F3-F7 and F4-F8 at theta frequency. The F-test at F7-T3 and F7-C3 theta surpassed the statistical threshold of P<0.003 (after Bonferroni correction). For all the above connection-frequency pairs, there was a dose-dependent trend in the connectivity strengths of the alleles as follows: Val/Val>Val/Met>Met/Met. Our analyses complemented previous literature regarding neural modulation by the COMT Val158Met polymorphism. The implication to the pathogenesis in schizophrenia was also discussed. Further studies are needed to clarify whether there is gender difference on this gene-brain interaction. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 13 | Psychiatr Danub 2011 Dec 23: 355-62 |
| PMID | 22075736 |
| Title | Quantitative electroencephalography in schizophrenia and depression. |
| Abstract | Standard (qualitative) electroencephalography (EEG) is routinely used in the diagnostic evaluation of psychiatric patients. Quantitative EEG (qEEG) findings differ between patients with schizophrenia, patients with depression, but results are not consistent. The aim of our study was to determine the differences in qEEG parameters between patients with schizophrenia, patients with depression, and healthy subjects. The study included 30 patients with schizophrenia, 33 patients with depression, and 30 healthy subjects. All study participants underwent standard EEG. Artifact-free 100-second epochs were selected from the recorded material and analyzed with Fast Fourier Transformation (FFT) analysis. The results are presented as absolute spectral power values (?V2) of delta, theta, alpha, and beta components of the EEG spectrum. EEGs were recorded from 12 locations including Fp1, Fp2, F3, F4, F7, F8, T3, T4, P3, P4, O1, and O2. In comparison with healthy subjects, patients with schizophrenia showed increased delta, theta, and beta activity and decreased alpha activity. Similar results were obtained in patients with depression, but in fewer regions. In patients with schizophrenia, delta power over Fp1, Fp2, F4, and F8 regions was increased in comparison with those in patients with depression. Interhemispheric asymmetry was found in patients with schizophrenia and healthy subjects, but not in patients with depression. The finding that patients with schizophrenia differed from patients with depression in delta power values could be potentially used in differential diagnosis between schizophrenia and depression. The role of qEEG in clinical differentiation between these two mental disorders may be especially important in cases of negative-symptom schizophrenia. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 14 | Conf Proc IEEE Eng Med Biol Soc 2013 -1 2013: 3286-90 |
| PMID | 24110430 |
| Title | A study on validity of cortical alpha connectivity for schizophrenia. |
| Abstract | Abnormalities in schizophrenia are thought to be associated with functional disconnections between different brain regions. Most previous studies on schizophrenia have considered high-band connectivity in preference to the Alpha band, as there has been some uncertainty correlating the latter to the condition. In this paper we attempt to clarify this correlation using an Electroencephalogram (EEG) analysis of the Alpha band from schizophrenic patients. Global, regional Omega and dimensional complexity and local Omega complexity differentials (LCD) of single channel are calculated using 16 channels of resting EEG data from 31 adult patients with schizophrenia and 31 age/sex matched control subjects. It was found that, compared to the controls, anterior alpha Omega and dimensional complexity are higher in schizophrenia patients (p<0.05) with the single channel LCD also increasing at FP1, FP2, F7 and F8 electrodes. Furthermore, higher left hemisphere dimensional complexity and LCD at T3 point was also found. The results suggest there is lower connectivity in the pre-frontal and left temporal regions with respect to the alpha band in schizophrenia patients. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 15 | Conf Proc IEEE Eng Med Biol Soc 2013 -1 2013: 3286-90 |
| PMID | 24110430 |
| Title | A study on validity of cortical alpha connectivity for schizophrenia. |
| Abstract | Abnormalities in schizophrenia are thought to be associated with functional disconnections between different brain regions. Most previous studies on schizophrenia have considered high-band connectivity in preference to the Alpha band, as there has been some uncertainty correlating the latter to the condition. In this paper we attempt to clarify this correlation using an Electroencephalogram (EEG) analysis of the Alpha band from schizophrenic patients. Global, regional Omega and dimensional complexity and local Omega complexity differentials (LCD) of single channel are calculated using 16 channels of resting EEG data from 31 adult patients with schizophrenia and 31 age/sex matched control subjects. It was found that, compared to the controls, anterior alpha Omega and dimensional complexity are higher in schizophrenia patients (p<0.05) with the single channel LCD also increasing at FP1, FP2, F7 and F8 electrodes. Furthermore, higher left hemisphere dimensional complexity and LCD at T3 point was also found. The results suggest there is lower connectivity in the pre-frontal and left temporal regions with respect to the alpha band in schizophrenia patients. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |