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H P Volz

Publications and source records attributed to H P Volz.

At least 19 recordsLinked to original sources
PubMed1999

Impaired sensory processing in male patients with schizophrenia: a magnetoencephalographic study of auditory mismatch detection.

The generation of mismatch negativity (MMN) as a component of auditory evoked event-related brain potentials has been reported previously to be severely disturbed in patients with schizophrenia. In the present study, we extended these findings to magnetoencephalography and investigated the neuromagnetic mismatch field (MMNm) in 15 male schizophrenic inpatients as compared to 16 healthy male volunteers. A standard tone of 1000 Hz and three different types of mismatch (1050-Hz tone, 5000-Hz tone, tone omission) were employed within the same paradigm, each mismatch occurring with a 10% pseudorandom probability. After correction for eye artifacts, the mean global field power of the mismatch reaction was calculated. Mismatch generation in patients with schizophrenia proved to be significantly impaired for all three conditions. This result confirms the theory of impaired auditory information processing in patients with schizophrenia at the level of the primary auditory cortex. Deficient generation of MMNm probably represents an impaired generation and/or faster decay of the sensory memory trace on the basis of disturbed sensory processing in male patients with schizophrenia.

Adult↗
PubMed1998

31Phosphorus magnetic resonance spectroscopy of the dorsolateral prefrontal region in schizophrenics--a study including 50 patients and 36 controls.

BACKGROUND: In a preliminary study we found decreased phosphodiester (PDE)% values and an increased phosphomonoester (PME)/phosphodiester ratio in the dorsolateral prefrontal region (DLPFR) of 13 chronic schizophrenics vs. 14 controls using 31phosphorus magnetic resonance spectroscopy (31P-MRS). Since these results are in contrast to the findings of other groups, we increased our study group to a total of 50 chronic schizophrenics on stable neuroleptic medication and 36 controls to minimize the possibility of a chance result due to small sample size. METHODS: An image-selected in vivo 31P-MRS method on a Philips Gyroscan ACS II scanner working at 1.5 T was used. RESULTS: We could confirm our earlier findings of decreased PDE% levels in schizophrenics. Additionally, we found phosphocreatine (PCr)% and PCr/adenosine triphosphate (ATP) to be increased in the schizophrenics. While no association between PME% and PDE% with neuroleptic medication was found, ATP% correlated positively and PCr/ATP negatively with the chlorpromazine equivalent dose. CONCLUSIONS: The decreased PDE% levels might be characteristic only for chronic, neuroleptic-treated patients. The finding of altered high-energy phosphate levels can be interpreted as an indication of decreased energy-demanding processes in the DLPFR of the investigated patients compared to controls.

Adenosine Triphosphate↗
PubMed1998

High-energy phosphates in the frontal lobe correlate with Wisconsin Card Sort Test performance in controls, not in schizophrenics: a 31phosphorus magnetic resonance spectroscopic and neuropsychological investigation.

In recent years, a number of 31phosphorus magnetic resonance spectroscopy (P-MRS) studies on the frontal lobe of schizophrenics have been performed, reporting alterations of phospholipids and high-energy phosphates. Deicken et al. (1994b) recently found positive correlations between left frontal phosphomonoester% (PME%) levels and the performance of a specific frontal lobe task, the Wisconsin Card Sorting Test (WCST), in schizophrenics. In the present paper, the correlations between phospholipids and high-energy phosphates in the frontal lobe of 26 schizophrenics and 23 controls measured with a volume-selective P-MRS method were investigated. Overall, we could not find any correlations between WCST results and phospholipid levels, but in controls phosphocreatine% (PCr%) and PCr/adenenosine triphosphate (ATP) ratios were negatively correlated with test performance. Since PCr behaves as a buffer of ATP, in the sense that when ATP is consumed by neuronal activity PCr is catalysed rapidly to ATP, increased PCr% values and, moreover, increased PCr/ATP ratios point to a decreased ATP consumption. Thus, the correlations found between PCr% and PCr/ATP and test performance in controls point to an association between reduced performance in a specific frontal lobe task and decreased energy demanding processes at rest. This association was not found in schizophrenics, possibly due to the influence of neuroleptic medication or the disease process per se.

Adenosine Triphosphate↗
PubMed1998

[Sex specific differences in hemispheric lateralization in schizophrenia? An MEG-MRI study].

In this magnetoencephalography study the issue of hemispheric lateralisation in patients with schizophrenia was addressed using acoustically evoked neuromagnetic fields. The characteristics of dipoles in the superior temporal gyrus, the primary auditory cortex, were calculated. In contrast to other studies, alterations did not concern the localisation, but rather the orientation of dipoles. Of pathophysiological interest was that the dipoles abnormalities were found left-hemispherically in male (p = 0.02) and right-hemispherically in female patients with schizophrenia (p = 0.01) when compared to controls. The findings suggest gender-specific alterations of hemispheric lateralisation in schizophrenia.

Adult↗
PubMed1998

Challenging the anterior attentional system with a continuous performance task: a functional magnetic resonance imaging approach.

Combining the Continuous Performance Test (CPT) with a modern functional imaging technique provides a powerful tool for investigating neurophysiological processes in the human brain. There is increasing evidence from single photon emission tomography (SPECT), positron emission tomography (PET) and presently also functional magnetic resonance imaging (fMRI) studies proposing the existence of a distributed large-scale attentional network, mediated by the dorsolateral prefrontal and mesial frontal cortex, thalamus, basal ganglia and posterior parietal and superior temporal lobe. The aim of this study is to show that fMRI is a useful tool for in vivo localization of attentional tasks and to compare the results with established imaging techniques. Functional MRI was performed on a clinical 1.5-T system using gradient-echo acquisition. For data processing, the Statistical Parametric Mapping (SPM96) package was used. A right lateralized activation pattern in the dorsolateral prefrontal and mesial frontal cortex, the thalamus and the basal ganglia was found in a group of 12 male subjects. These findings support theories suggesting right hemispheric dominance of human attention.

Adult↗
PubMed1998

31P magnetic resonance spectroscopy in the frontal lobe of major depressed patients.

Most research with 31P-magnetic resonance spectroscopy (31P-MRS) in affective disorders has been done in the field of bipolar disturbances. Reduced frontal and temporal lobe phosphomonoester (PME) concentrations were measured in the euthymic state, whereas increased values were found in the depressed state. In bipolar-II patients reduced phosphocreatine (PCr) concentrations were reported in the euthymic, depressed, and manic state. The aim of the present study was to explore whether PME and PCr were also altered in the frontal lobe of major depressed, unipolar patients. Therefore, we used 31P-MRS to investigate the relative phospholipid and high-energy phosphate concentrations in the frontal lobe of 14 unipolar patients, mostly medicated, and 8 age-matched controls. We found increased PME and decreased ATP values. Other 31P-MRS parameters were not different in both groups. Phosphomonoester percentages correlated negatively with the degree of depression. Thus, the main alterations found in bipolar depressed patients could also be demonstrated in unipolar depressed patients. The results are discussed with regard to disturbed phospholipid and intracellular high-energy phosphate metabolism in depressed patients.

Adenosine Triphosphate↗
PubMed1998

Cognitive stimulation with the Wisconsin Card Sorting Test: functional MR imaging at 1.5 T.

PURPOSE: To determine whether functional magnetic resonance (MR) imaging can demonstrate a specific pattern of cerebral activation during cognitive stimulation by using a high-level cognitive task such as the Wisconsin Card Sorting Test. MATERIALS AND METHODS: Thirty-one healthy volunteers underwent functional MR imaging with a 1.5-T MR imager with a standard head coil (100/50 [repetition time msec/echo time msec], 230-mm field of view, 40 degrees flip angle, 256 x 256 matrix). For stimulation, a personal computer version of the Wisconsin Card Sorting Test was used. Image analysis was done off-line, and cross-correlation coefficients between the stimulus function and the signal intensity response were calculated on a pixel-by-pixel basis and overlaid onto the corresponding anatomic MR image for each volunteer. RESULTS: Stimulation resulted in strongly frontal activation, which included the mesial and the dorsolateral prefrontal cortexes, interconnected with Brodmann areas 44, 45, and 46. While activation was often bilateral, the largest area of activation was in the right hemisphere. Activation also was found in the basal ganglia and the mesial thalamic nuclei. CONCLUSION: Functional MR imaging can demonstrate a specific pattern during activation with a cognitive task. Functional MR imaging has promise for more precise anatomic and functional imaging studies of brain interaction than have other imaging modalities.

Adult↗
PubMed1998

Monoamine oxidase inhibitors. A perspective on their use in the elderly.

Monoamine oxidase inhibitors (MAOIs) are mainly used in psychiatry for the treatment of depressive disorders and in neurology for the treatment of Parkinson's disease. While the classical, nonselective and nonreversible MAOIs, such as phenelzine and tranylcypromine, are characterised by the risk of inducing a hypertensive crisis when dietary tyramine is ingested, the selective monoamine oxidase-B (MAO-B) inhibitor selegiline (deprenyl) and, even more so, the selective and reversible monoamine oxidase-A (MAO-A) inhibitor moclobemide, are free from this potential interaction. Drug tolerability data for the elderly show that moclobemide is one of the most well tolerated compounds. Selegiline, especially when used in combination with levodopa, can cause anorexia, dry mouth, dyskinesia and, most problematic, orthostatic hypotension. For the traditional MAOIs, phenelzine and tranylcypromine, published data are insufficient to be able to give a conclusive tolerability statement regarding the use of these compounds in elderly people. Although orthostatic hypotension occurs in most patients treated with traditional MAOIs, the incidence in elderly patients with depression does not appear to be greater than that reported with tricyclic antidepressants.

Aged↗
PubMed1997

Decreased energy demanding processes in the frontal lobes of schizophrenics due to neuroleptics? A 31P-magneto-resonance spectroscopic study.

In the present investigation on 31P-magneto-resonance spectroscopic parameters in the frontal lobe, we found phosphocreatine levels and the ratio phosphocreatine/adenosine triphosphate to be increased (12.62 +/- 1.98% resp. 0.31 +/- 0.06) in 50 neuroleptic-treated schizophrenics, whereas no differences were detected in 10 neuroleptic-free patients (11.66 +/- 2.57% resp. 0.29 +/- 0.08) compared to 36 controls (11.37 +/- 1.45 resp. 0.29 +/- 0.04). This result points to a major role of neuroleptics in the metabolism of high-energy phosphates.

Adenosine Triphosphate↗
PubMed1997

Brain activation during cognitive stimulation with the Wisconsin Card Sorting Test--a functional MRI study on healthy volunteers and schizophrenics.

It has been demonstrated by single photon emission computed tomography (SPECT) and positron emission tomography (PET) that frontal brain regions are stimulated during performance of the Wisconsin Card Sorting Test (WCST). The WCST is also regarded as one of the standard tests for the assessment of frontal activity in brain imaging studies of schizophrenia. In this study cerebral activation was assessed by means of functional magnetic resonance imaging (fMRI). In healthy volunteers WCST stimulation resulted in a right lateralized frontal activation. In 13 chronic schizophrenics on stable neuroleptic medication, a lack of activation in the right prefrontal cortex and--as a trend--an increased left temporal activity during execution of the WCST was noted compared to controls. Since a one-slice technique was used, no information about the activation pattern in adjacent brain regions was obtained. However, as fMRI possesses a superior spatial resolution compared to SPECT and PET, the anatomical localization of the activation effect in the measured slice can be defined more precisely. Beside these methodological considerations, the results are discussed in relation to prior findings of a reduced ability of schizophrenics to coordinate cerebral function.

Adult↗
PubMed1997

Abnormalities of auditory evoked magnetic fields and structural changes in the left hemisphere of male schizophrenics--a magnetoencephalographic-magnetic resonance imaging study.

Functional and structural changes in 10 DSM-III-R male schizophrenics and 10 healthy volunteers were investigated using magnetoencephalographically (MEG) detected long-latency (N100 m) auditory evoked fields (AEFs) and magnetic resonance imaging (MRI). The AEFs were characterized by single moving equivalent dipoles, which were superimposed on MRIs. There were significant differences in dipole orientations and in AEF latencies in the left hemisphere of schizophrenics, when compared to the controls. The MEG-detected alterations were found to be associated with a bilateral volume reduction of the posterior superior temporal gyrus (pSTG), which was more pronounced in the left hemisphere. Separate analysis of white and gray matter has shown that the pSTG volume reduction resulted from decreased gray matter volumes without white matter changes. Both the functional and the morphological data indicate a left-hemispheric disturbance in our patients.

Adult↗
PubMed1997

[Fluoxetine].

Explore the source record for details and available documents.

Animals↗
PubMed1997

31P magnetic resonance spectroscopy in the dorsolateral prefrontal cortex of schizophrenics with a volume selective technique--preliminary findings.

Pettegrew et al (Arch Gen Psychiatry 48:563-568, 1991) were the first to determine abnormalities concerning phospholipids and high energy metabolites in the dorsolateral prefrontal cortex of drug-naive schizophrenics with 31P magnetic resonance spectroscopy (MRS). Other investigations could not replicate these findings. We included in our study 13 schizophrenic inpatients and 14 age-matched controls. Whereas Pettegrew et al found increased levels of phosphodiesters and decreased levels of phosphomonoesters we measured decreased levels of phosphodiesters in the schizophrenics as compared to controls. One possible explanation for the contradictory findings of the both trials might be the different localization techniques used.

Adult↗
PubMed1997

Brofaromine versus imipramine in in-patients with major depression--a controlled trial.

Brofaromine is a selective and reversible inhibitor of monoamine oxidase A. The efficacy and safety of this compound as compared with tricyclic antidepressants, classical monoamine oxidase inhibitors and placebo has been demonstrated in several clinical trials. The present 6-week, double-blind, randomized trial compared brofaromine with imipramine in in-patients with major depression. Brofaromine was as effective as imipramine in the treatment of major depression, but exhibited a different side-effect profile, in particular lacking the anticholinergic and certain cardiovascular side-effects of the tricyclic imipramine, but more likely to induce sleep disturbances. In this study, in-patients were examined, since the majority of controlled clinical trials on depressed patients conducted so far have focused on the evaluation of out-patients. If one assumes that a different degree of severity of depression exists between these two patient groups, then the results of those trials conducted on out-patients cannot readily be transferred to in-patients.

Adolescent↗
PubMed1997

Pramipexole as adjunct to haloperidol in schizophrenia. Safety and efficacy.

Pramipexole, a presynaptic dopamine D2/D3 autoreceptor agonist, has been given to haloperidol-treated patients with schizophrenia (n = 15) in an effort to ameliorate residual positive and negative symptoms that have not been satisfactorily influenced by haloperidol alone. Total scores of the positive and negative symptom scale (PANSS) decreased by more than 20% in 9 of 15 patients (reduction of total score: 22-62%). Serious adverse events did not occur. Three of the 15 patients dropped out due to worsening of schizophrenia. Insomnia, as the most frequent side effect, occurred in 4 patients. No clinically relevant electrocardiographic and laboratory changes were reported. This study supports the safety of the treatment of schizophrenia with pramipexole and haloperidol as a combination therapy. However, further clinical studies are required to support these preliminary findings.

Adult↗