| 1 | J. Nucl. Med. 2003 May 44: 671-81 |
|---|---|
| PMID | 12732667 |
| Title | A truly simultaneous combination of functional transcranial Doppler sonography and H(2)(15)O PET adds fundamental new information on differences in cognitive activation between schizophrenics and healthy control subjects. |
| Abstract | Working memory deficits are a cardinal feature of the pathophysiology of schizophrenia. Lesion studies and functional blood flow-dependent imaging methods with coarse temporal resolution, such as PET and functional MRI (fMRI), tend to paint a fairly static picture of the cortical regions involved. In contrast, functional transcranial Doppler sonography (FTCD) provides a high temporal resolution. Truly simultaneous FTCD-fMRI is not yet possible for technical reasons, but H(2)(15)O PET and FTCD can be used really simultaneously. However, this combination has not yet been used for cognitive activations in schizophrenia. We therefore investigated the extent to which there are both spatial (PET) and temporal changes (FTCD) in the activation patterns of schizophrenic patients. Eleven clinically stable chronic schizophrenic, right-handed patients and 10 healthy, right-handed control subjects, matched for age, sex, education, and intelligence quotient, participated in the study. We selected stable chronic schizophrenic patients who could perform a working memory task (N-back task) as well as healthy volunteers to exclude the possibility of imaged artifacts due to poor performance. All subjects were examined with a truly simultaneous FTCD-H(2)(15)O PET combination under cognitive activation. schizophrenic patients activate a significantly larger cortical volume for adequate task performance (P < 0.05), but with a significantly lower blood flow increase in this volume (P < 0.01), than do control subjects. Furthermore, they cannot significantly increase blood flow velocity during the time course of cognitive activation as control subjects do. There were only significant correlations between neuropsychologic performance and imaging parameters (FTCD changes, PET blood flow changes) in control subjects (all r >or= /0.65/; P < 0.05), but no significant correlations in schizophrenics (all r < /0.3/; P > 0.4). We demonstrated that schizophrenic patients exhibit qualitative differences in the spatial and temporal resolution of cognitive processing. All facts could be interpreted as a sign of alternative, less efficient problem-solving strategies in schizophrenia that lead to the working memory deficits observed during the further course of this disease. Truly simultaneous FTCD-PET can be used in neuroscience to add fundamental new information on spatial and temporal cognitive activation behavior to understand the true physiologic nature of the disease-specific differences of mental illnesses that are seen as disorders of the mind arising in the brain. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 2 | J. Nucl. Med. 2003 May 44: 671-81 |
| PMID | 12732667 |
| Title | A truly simultaneous combination of functional transcranial Doppler sonography and H(2)(15)O PET adds fundamental new information on differences in cognitive activation between schizophrenics and healthy control subjects. |
| Abstract | Working memory deficits are a cardinal feature of the pathophysiology of schizophrenia. Lesion studies and functional blood flow-dependent imaging methods with coarse temporal resolution, such as PET and functional MRI (fMRI), tend to paint a fairly static picture of the cortical regions involved. In contrast, functional transcranial Doppler sonography (FTCD) provides a high temporal resolution. Truly simultaneous FTCD-fMRI is not yet possible for technical reasons, but H(2)(15)O PET and FTCD can be used really simultaneously. However, this combination has not yet been used for cognitive activations in schizophrenia. We therefore investigated the extent to which there are both spatial (PET) and temporal changes (FTCD) in the activation patterns of schizophrenic patients. Eleven clinically stable chronic schizophrenic, right-handed patients and 10 healthy, right-handed control subjects, matched for age, sex, education, and intelligence quotient, participated in the study. We selected stable chronic schizophrenic patients who could perform a working memory task (N-back task) as well as healthy volunteers to exclude the possibility of imaged artifacts due to poor performance. All subjects were examined with a truly simultaneous FTCD-H(2)(15)O PET combination under cognitive activation. schizophrenic patients activate a significantly larger cortical volume for adequate task performance (P < 0.05), but with a significantly lower blood flow increase in this volume (P < 0.01), than do control subjects. Furthermore, they cannot significantly increase blood flow velocity during the time course of cognitive activation as control subjects do. There were only significant correlations between neuropsychologic performance and imaging parameters (FTCD changes, PET blood flow changes) in control subjects (all r >or= /0.65/; P < 0.05), but no significant correlations in schizophrenics (all r < /0.3/; P > 0.4). We demonstrated that schizophrenic patients exhibit qualitative differences in the spatial and temporal resolution of cognitive processing. All facts could be interpreted as a sign of alternative, less efficient problem-solving strategies in schizophrenia that lead to the working memory deficits observed during the further course of this disease. Truly simultaneous FTCD-PET can be used in neuroscience to add fundamental new information on spatial and temporal cognitive activation behavior to understand the true physiologic nature of the disease-specific differences of mental illnesses that are seen as disorders of the mind arising in the brain. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 3 | J. Nucl. Med. 2003 May 44: 671-81 |
| PMID | 12732667 |
| Title | A truly simultaneous combination of functional transcranial Doppler sonography and H(2)(15)O PET adds fundamental new information on differences in cognitive activation between schizophrenics and healthy control subjects. |
| Abstract | Working memory deficits are a cardinal feature of the pathophysiology of schizophrenia. Lesion studies and functional blood flow-dependent imaging methods with coarse temporal resolution, such as PET and functional MRI (fMRI), tend to paint a fairly static picture of the cortical regions involved. In contrast, functional transcranial Doppler sonography (FTCD) provides a high temporal resolution. Truly simultaneous FTCD-fMRI is not yet possible for technical reasons, but H(2)(15)O PET and FTCD can be used really simultaneously. However, this combination has not yet been used for cognitive activations in schizophrenia. We therefore investigated the extent to which there are both spatial (PET) and temporal changes (FTCD) in the activation patterns of schizophrenic patients. Eleven clinically stable chronic schizophrenic, right-handed patients and 10 healthy, right-handed control subjects, matched for age, sex, education, and intelligence quotient, participated in the study. We selected stable chronic schizophrenic patients who could perform a working memory task (N-back task) as well as healthy volunteers to exclude the possibility of imaged artifacts due to poor performance. All subjects were examined with a truly simultaneous FTCD-H(2)(15)O PET combination under cognitive activation. schizophrenic patients activate a significantly larger cortical volume for adequate task performance (P < 0.05), but with a significantly lower blood flow increase in this volume (P < 0.01), than do control subjects. Furthermore, they cannot significantly increase blood flow velocity during the time course of cognitive activation as control subjects do. There were only significant correlations between neuropsychologic performance and imaging parameters (FTCD changes, PET blood flow changes) in control subjects (all r >or= /0.65/; P < 0.05), but no significant correlations in schizophrenics (all r < /0.3/; P > 0.4). We demonstrated that schizophrenic patients exhibit qualitative differences in the spatial and temporal resolution of cognitive processing. All facts could be interpreted as a sign of alternative, less efficient problem-solving strategies in schizophrenia that lead to the working memory deficits observed during the further course of this disease. Truly simultaneous FTCD-PET can be used in neuroscience to add fundamental new information on spatial and temporal cognitive activation behavior to understand the true physiologic nature of the disease-specific differences of mental illnesses that are seen as disorders of the mind arising in the brain. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 4 | BMC Psychiatry 2006 -1 6: 25 |
| PMID | 16723019 |
| Title | Association between two distinct executive tasks in schizophrenia: a functional transcranial Doppler sonography study. |
| Abstract | schizophrenia is a severe mental disorder involving impairments in executive functioning, which are important cognitive processes that can be assessed by planning tasks such as the Stockings of Cambridge (SOC), and tasks of rule learning/abstraction such as the Wisconsin Card Sorting Test (WCST). We undertook this study to investigate the association between performance during separate phases of SOC and WCST, including mean cerebral blood flow velocity (MFV) measurements in chronic schizophrenia. Functional transcranial Doppler sonography (FTCD) was used to assess bilateral MFV changes in the middle (MCA) and anterior (ACA) cerebral arteries. Twenty-two patients with chronic schizophrenia and 20 healthy subjects with similar sociodemographic characteristics performed SOC and WCST during FTCD measurements of the MCA and the ACA. The SOC was varied in terms of easy and difficult problems, and also in terms of separate phases, namely mental planning and movement execution. The WCST performance was assessed separately for maintaining set and set shifting. This allowed us to examine the impact of problem difficulty and the impact of separate phases of a planning task on distinct intervals of WCST. Simultaneous registration of MFV was carried out to investigate the linkage of brain perfusion during the tasks. In patients, slowing of movement execution during easy problems (SOC) was associated with slowing during maintaining set (WCST) (P < 0.01). In healthy subjects, faster planning and movement execution during predominantly difficult problems were associated with increased performance of WCST during set shifting (P < 0.01). In the MCA, patients showed a significant and positive correlation of MFV between movement execution and WCST (P < 0.01). The results of this study demonstrate performance and brain perfusion abnormalities in the association pattern of two different tasks of executive functioning in schizophrenia, and they support the notion that executive functions have a pathological functional correlate predominantly in the lateral hemispheres of the brain. This study also underpins the scientific potential of FTCD in assessing brain perfusion in patients with schizophrenia. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |
| 5 | Clin Neurophysiol 2007 Jul 118: 1449-59 |
| PMID | 17452011 |
| Title | Impaired rapid modulation of cerebral hemodynamics during a planning task in schizophrenia. |
| Abstract | Patients with schizophrenia show deficits in planning, and the Stockings of Cambridge (SOC) is a task that assesses planning performance. This study was undertaken to investigate rapid changes of cerebral hemodynamics during separate phases of SOC in schizophrenia and normals by means of functional transcranial Doppler sonography (FTCD). We included 21 patients with chronic schizophrenia and a control group of 20 healthy subjects in the study. They underwent FTCD of the middle (MCA) and anterior cerebral arteries (ACA) during performance of SOC. The main finding was that healthy subjects significantly modulated the early cerebral hemodynamic response along distinct conditions of SOC, whereas we observed no significant differences in patients. Normally, there was an up-regulation of cerebral hemodynamics during mental planning, and about zero values were observed during movement execution. Patients showed lower development of the early cerebral hemodynamic response during planning of SOC. The findings of this study suggest a uniform pattern of cerebral hemodynamic regulation during a planning task in schizophrenia, whereas healthy subjects modulated such a response along a planning-movement execution sequence. We provide novel evidence that modulation of cerebral hemodynamics is compromised in schizophrenia, and that FTCD constitutes a proper method to measure these alterations. |
| SCZ Keywords | schizophrenia, schizophrenic, schizophrenics |