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Biomedical subjects

K Maurer

Publications and source records attributed to K Maurer.

At least 109 records · Page 6Linked to original sources
PubMed1992

IRAOS: an instrument for the assessment of onset and early course of schizophrenia.

Since Kraepelin's first description of dementia praecox in 1889 many data and theories have been published on the onset and course of schizophrenia. Until now studies on these topics had to rely on first admission data and on the subsequent course of the disease. However, first hospitalisation is preceded by a wide variety of patterns and duration of the early course. Items taken from the pre-admission phase of the disease are often incorrectly used as premorbid characteristics, understandably preceding the subsequent course and outcome of schizophrenia with high predictive power. In relation to our interest to study the beginning of schizophrenia, systematically, paying special attention to the age and gender distribution of true onset and the symptomatology and pattern of the early and later course, we developed an 'Interview for the Retrospective Assessment of the Onset of Schizophrenia (IRAOS)'. It allows an objective, reliable, and valid assessment of the symptoms, psychological impairments, demographic and social characteristics as well as the referring points in time of the early course of psychosis. The instrument is administered as a semi-structured interview with both the patient and a key informant. The obtained information is extended by a systematic examination of the clinician's case notes. Some results derived from an ongoing study on age and gender differences in onset and patterns of early course are added to demonstrate the use of the instrument.

Combined Modality Therapy↗
PubMed1992

[Importance of the EEG in early and differential diagnosis of dementia of the Alzheimer type].

The development of new parameters in the quantitative evaluation of EEG provides new diagnostic opportunities for the clinician. Reviewing all published papers on EEG and dementia over the last 10 years revealed 30 out of 428 studies discussing EEG alterations in relation to the severity of the disease. This approach provides useful information for early and differential diagnosis of dementia. Besides a generalised slowing-down represented by an increase of delta and theta and a decrease of alpha and beta in the frequency spectrum (also characterised by a reduction of the peak frequency), the topography of the alterations changes depending on the severity of the disease. For instance, the alpha activity loses its normally occipital orientation. In early stages of the disease, it is measured parietally ("anteriorized"). In advanced stages, the activity is equally distributed over the scalp. Some studies found significant alterations even in early stages of the disease, most pronounced in theta and beta activity, making the EEG a useful tool for the early diagnosis of dementia. But studies on the differential diagnostic value are lacking. The value of EEG could be improved after parameters like the EEG segmentation or the traditional parameters combined with cognitive stimulation have been sufficiently evaluated.

Aged↗
PubMed1992

Quantitative topographical analysis of effects of single thiopental bolus on human electroencephalogram.

The aim of present study was to characterize the topographical effect of thiopental on the EEG during induction of anesthesia. A multichannel (19 channels) digital EEG was recorded in 10 patients undergoing surgical treatment. The period during induction of anaesthesia before intubation was investigated in regard to peak frequency, amplitude, topography, and amplitude in conventional frequency bands. The main findings were a slowing of the EEG with a simultaneous increase of amplitude in the predominant EEG frequency (peak frequency) during induction. The topographical analysis showed a clear change of localization of the peak frequency in the occipito-frontal direction. Berger described the effect of thiopental on electrical cortical activity as early as 1933. Since then, many studies have investigated its influence on the EEG, but few have tried to characterize the effects of topographical changes in a quantitative way.

Adult↗
PubMed1992

Changes in P300 latency and amplitude in schizophrenic patients and healthy controls during the examination.

In 30 schizophrenic patients (sixteen of the paranoid subtype, 14 of the nonparanoid) and healthy controls (n = 30) event-related potentials were obtained with a somatosensory reaction-time (RT) version of the "oddball paradigm" by stimulating the right (first run) and the left (second run) median nerve. Variations of P300 amplitude and latency and of RT within the average (30 trials) were studied by fractionating off-line the original averages in three subaverages. After stimulation of the right median nerve oscillations on P300 amplitude and latency were observed. After stimulation of the left median nerve there was a trend toward a decrease of the P300 amplitude that reached significance at the electrode P3 for patients (p = 0.014) and at the electrode P4 for controls (p = 0.025). The P300 latency showed variations for patients and controls. The mean-RT was prolonged across the subaverages only for schizophrenics, reaching significance after stimulation of the right median nerve. Paranoid and nonparanoid schizophrenic patients showed similar results on P300 and RT parameters across the subaverages. These results are discussed in terms of the influence of motivation and task involvement on the P300 amplitude. These could be unspecific factors that account for the habituation of the P300 along the examination.

Adult↗
PubMed1992

Functional relationship between brain regions in schizophrenia evaluated with Pearson's correlation between event-related potentials.

As part of a study of the somatosensory P300 event-related potential (ERP) in paranoid and nonparanoid schizophrenic patients (8) Pearson's product-moment correlations between ERP waveforms were calculated to study the functional relationship between brain areas. ERP were recorded from F3, F4, P3 and P4; interhemispheric (F3 to F4; P3 to P4) and intrahemispheric (F3 to P3; F4 to P4) correlations were obtained. There was no significant difference among the paranoid and nonparanoid patients and healthy controls for both the interhemispheric and the intrahemispheric correlations. The lack of disruption of functional relationship between brain areas on the patients do not support the hypofrontality and the laterality hypothesis of schizophrenia. However, the use of neuroleptics by the patients, the study of the whole waveforms and not parts of them and the use of linked-ears reference could account for these negative results.

Adult↗
PubMed1991

Electroencephalographic mapping during isoflurane anesthesia for treatment of mental depression.

Seven patients undergoing isoflurane anesthesia were studied using electroencephalographic (EEG) mapping, a computer-assisted technique of EEG processing that permits the analysis of the spatial distribution of frequency components of the human EEG. After induction with thiopental, the patients were hyperventilated (carbon dioxide tension, 25 to 28 mm Hg) with 4% isoflurane in oxygen until a burst-suppression EEG appeared. Brain electrical activity was compared before anesthesia, at 0.5 to 0.8% and 1.8 to 2.1% isoflurane, during bursts, and after anesthesia. Starting from an alpha EEG with occipital predominance, a distinct alpha activation appeared over the whole cortex during 0.5 to 0.8% isoflurane. Decreased alpha amplitude with a maximum over the frontotemporal regions was observed during 1.8 to 2.1% isoflurane. Bursts consisted of high amplitude in all frequency bands. In the delta and the theta bands, voltage was very low before isoflurane administration, and increased in relation to depth of anesthesia. A minimum in delta and theta amplitudes occurred over both central regions. The dominant frequency, defined as the frequency component with the highest amplitude in the frequency spectrum, decreased from 8 to 4 and finally to 1 Hz, while its amplitude increased from 3 to 13 microV. As anesthesia deepened, the dominant frequency shifted from the occiput to the frontal cortex. Brain mapping transfers an immense amount of electroencephalographic (EEG) data into a comprehensive, easily readable image of brain function during anesthesia for therapy of mental depression. To make use of this technique in the operating room, further investigation and development toward on-line mapping are necessary.

Adult↗
PubMed1991

Integrity of the blood-CSF barrier in dementia of Alzheimer type: CSF/serum ratios of albumin and IgG.

Serum and cerebrospinal fluid (CSF) from 25 patients with dementia of Alzheimer type (DAT) and 25 controls were assayed for concentrations of albumin and IgG. The severity of dementia was rated with the Mini Mental State Examination. The CSF/serum ratio for albumin and IgG as well as the IgG index were used to evaluate blood-CSF barrier function in the respective groups. The control group was matched for age, sex and the indirect alcohol parameters, mean corpuscular volume and gamma-glutamyltranspeptidase. There were no signs of dysfunction of the blood-CSF barrier for proteins or signs of local synthesis of IgG in the central nervous system (CNS) of the demented patients. The permeability of the blood-CSF barrier appeared to be unrelated to dementia severity. The data do not support the hypothesis that a pathological leakage through the blood-CSF barrier facilitates the entry of extraneuronal proteins to the CNS, which might contribute to the pathophysiological process in DAT.

Aged↗
PubMed1991

Topography of the quantitative electroencephalogram in dementia of the Alzheimer type: relation to severity of dementia.

Conventional electroencephalographic (EEG) frequency bands and peak frequency were investigated in patients with probable dementia of the Alzheimer type (DAT). Measures of EEG topography and activity were also related to the severity of dementia, as assessed by neuropsychological tests. EEG activity measured in conventional frequency bands proved to be the most sensitive parameter for the quantitative differentiation of DAT, whereas the topography of peak frequency was the better qualitative discriminator between healthy subjects and DAT patients.

Aged↗
PubMed1991

[Sex differences in schizophrenic diseases].

Sex differences in schizophrenic diseases have been known for a long time but have also been subject to long-term neglect by psychiatric epidemiological research, although a study of these sex differences could, in our opinion, yield valuable pointers to pathogenic factors involved in this group of diseases the aetiology of which still awaits clarification. For this reason we initiated large-scale investigations focussed on this topic. The paper presented here discusses a few initial results, basing on data of Mannheim and National Danish Case Records and on our own study on schizophrenia, the latter being a representative record of 392 patients hospitalised for the first time in the Rhine-Neckar region and the eastern part of the Palatinate. First of all, sex differences at the age at which the disease appeared for the first time, were studied while paying close attention to artifacts and other, usually neglected methodical error sources. The difference in the average age of the sexes at first hospitalisation was confirmed, and also--using an instrument specially developed for that purpose--at the onset of the disease. At the time the first signs of the disease are noticed and the first schizophrenic symptoms become apparent, men are about 3 to 4 years younger than women. On the other hand, the cumulative lifetime risk--calculated up to 60 years of age--seems to be the same for both sexes. It appears that there are no sex differences in the pattern of symptoms of the disease at the time of initial hospital admittance, in respect of both the most common and the characteristic signs and symptoms. There were significant although quantitatively not very great differences in respect of patient behaviour which displays socially positive aspects somewhat more often in women and socially negative ones distinctly more often in men. In respect of the course of the disease we could not find any marked sex differences over a period of 10 years after onset of the disease; however, this is presently based only on the Danish case record data and on criteria of the course of the disease, such as number and duration of inpatient treatments.

Adolescent↗
PubMed1991

[Experiences with "Schedules for Clinical Assessment in Neuropsychiatry (SCAN)" within the scope of a multicenter field study].

The "Schedules for Clinical Assessment in Neuropsychiatry" (SCAN), a comprehensive set of clinical assessment instruments were developed by the World Health Organization (WHO) and the London Institute of Psychiatry. A central aim is to provide clinicians and researchers with a standardized interview for ICD-10 diagnoses. Core instrument of SCAN is the 10th version of the "Present State Examination" (PSE) which has proved to be one of the most helpful psychopathological assessment instruments. PSE-10 covers a wide range of non-psychotic as well as of psychotic symptoms and includes special modules for ICD-10 and DSM-IIIR diagnoses, e.g. alcohol and drug abuse, sleeping and eating disorders. A computer program (CATEGO-V) is also developed for standardized scoring and diagnostics. The paper introduces SCAN by describing its structure and applicability. Different rating periods and scales are explained, and PSE-10 is contrasted with PSE-9 in a whole. SCAN experiences within a reliability study are reported, completed by a critical evaluation of the most recent version of the SCAN system.

Adolescent↗
PubMed1991

[A computer algorithm for diagnostic assessment with DSM-III in the early course of schizophrenic diseases].

The purpose of the computer algorithm described here is the evaluation of diagnostic criteria according to DSM-III for schizophrenia and schizophreniform disorders. It also dates the first time point of the assessment of these diagnoses. The necessary information comes from a semistructured interview, called IRAOS (Interview for the Retrospective Assessment of the Onset of Schizophrenia). With this interview early indicators of a beginning schizophrenia can be evaluated in their chronological order and their type of course. The algorithm was first used in a sample of patients admitted for the first time with a diagnosis of either schizophrenia or paranoid psychosis. One third of these patients fulfills the DSM-III-criterion of a duration of at least six months. The other patients fulfill criterion B of a schizophreniform disorder. To strengthen the validity of a diagnosis including the criteria A up to E successively, the sample is reduced to 70%. The average time point of the first assessment of the diagnosis by the computer algorithm is about 1.5 years before the index-admission. Together with the IRAOS the computer algorithm allows an operationalized assessment of the real onset of schizophrenia.

Adult↗
PubMed1991

[Sex differences in age of onset, symptomatology and evolution of schizophrenia].

Gender differences in age at onset, symptomatology and course of schizophrenia are examined by analyzing case register data and by direct investigation of a representative sample of first-admitted patients. The main finding that males fall ill at an earlier age than females can be confirmed even after ruling out other interpretations due to sample bias, different time span between real onset and first hospital admission, gender differences in symptom development or other confounding factors. When looking for causes of these gender differences it seems that disturbances in early social development must be understood as a consequence of beginning schizophrenia rather than a prerequisite. The need for explanatory models is stressed that allow for the empirical testing of hypotheses concerning gender specific development of schizophrenia.

Age Factors↗
PubMed1991

[Schizophrenia and age].

The association of age with time of onset, symptomatology and early course of schizophrenia was studied on a large, representative sample of first-admitted patients with a diagnosis of schizophrenia (nuclear and related diagnoses) from a total population of about 1.5 million by using a semi-structured interview (IRAOS) developed specifically for this purpose. As a result an age distribution differing between men and women was obtained when the appearance of the first sign of a mental disturbance was studied. 61.6% of the men and 47.4% of the women fell ill prior to the age of 25. Negative symptoms and the early course of the disease turned out to be relatively independent of age at onset. The few age differences observed with positive and unspecific symptoms seem to be accounted for by factors not specific for schizophrenia, such as slightly increased anxiety at young age, slightly increased depressiveness in early adulthood and slightly increased paranoid delusions later in adulthood. At young age delusional symptoms, probably as an expression of immature personality, are less stable, less differentiated and less systematized, whereas fully developed delusions of persecution become more frequent at higher age. An unexpected finding was a comparatively high proportion of lengthy phases characterized by negative symptoms prior to first admission in late-onset schizophrenia in females. Hence, beginning schizophrenia seems to be a fairly uniform pattern of response at all ages, female sex appearing to be the only factor independent of the disease that influences it to any significant extent by delaying onset.

Adolescent↗
PubMed1990

Temperature dependence of the electrical and mechanical responses of the adductor pollicis muscle in humans.

Changes at low temperatures of the electrical and mechanical activity of the adductor pollicis muscle were studied in 10 volunteers. Decreasing temperatures resulted in increased amplitude and duration of the negative phase and peak-to-peak amplitude of the evoked muscle action potential. Distal latency, electromechanical latency, contraction time, and half-relaxation time were also increased while isometric force, contraction velocity, and relaxation velocity were decreased. The increase of contraction time is greater over the temperature range below 28 degrees C than above 29 degrees C. Skin temperature differs significantly from muscle temperature, showing about 3 degrees C lower values during cooling and up to 4 degrees C higher values during rewarming with radiant heat.

Action Potentials↗
PubMed1990

P3 topography in psychiatry and psychopharmacology.

Endogenous components of event related potentials are of particular interest in psychiatric diseases because of their relations to cognitive and behavioral processes. We studied the topography of these potentials in order to find out whether there are different scalp distributions in schizophrenic and depressive patients in relation to the psychopathological state and compared to normal controls. Furthermore variations of the topographical scalp distribution of P300 in normal volunteers after administration of physostigmine and biperiden was investigated. We demonstrated a clear relationship of the P300 amplitude with the negative symptom axis and found different topographical scalp distributions in different groups and experimental conditions. Topography of event related potentials is therefore a promising field of investigation for a better understanding of psychiatric disorders.

Adolescent↗
PubMed1990

Glucocorticoid receptors on mononuclear leukocytes in Alzheimer's disease.

Several lines of evidence suggest disturbances of the hypothalamic-pituitary-adrenal (HPA) system in Alzheimer's disease (AD). In an exploration of the potential role of the glucocorticoid receptor (GR) in AD, GR density and affinity were assessed on mononuclear leukocytes of 12 AD patients and 12 healthy controls. GR binding characteristics did not differ between patients and controls or between patients subdivided according to diagnosis or associated clinical features. These data suggest that the abnormalities of the HPA system in AD are not related to a GR deficiency.

Adrenocorticotropic Hormone↗