[P300 in mild cognitive impairment and in dementia].

Objectives: The late component of the event-related potential (ERP), P300 is a marker for cognitive brain functions. The objective of this study was to examine P300 parameters in dementia and in mild cognitive impairment (MCI), to examine whether there is a correlation between the changes in P300 parameters and the type and severity of dementia, and to determine P300 abnormalities in MCI in relation to the presence/absence of CT/MRI abnormalities.

Method: Auditory event-related potentials, P300 were recorded in 28 MCI patients (14 of them with normal CT/MRI findings and 10 subjects with mild ventricular enlargement).

Automated Neuropsychological Test Battery (CANTAB) in mild cognitive impairment and in Alzheimer's disease.

Neuropsychological deficits, such as poor episodic memory, are consistent features of mild cognitive impairment and also that of early stage of dementia. The aim of the present study was to detect cognitive dysfunction among patients with Alzheimer's disease or with mild cognitive impairment (MCI), which refers to a transitional state between the cognition of normal aeging and mild dementia regarded as a high-risk condition for the development of clinically probable Alzheimer's disease (AD). Computerized tests of memory, attention and executive functions were studied in groups of AD subjects (n=15) and MCI subjects (n=25).

[Switching patients with schizophrenia to ziprasidone from conventional or other atypical antipsychotics].

Objectives: The aim of the study was to assess the efficacy, tolerability and safety of ziprasidone in patients with schizophrenia who were already treated with conventional or other atypical antipsychotics that had to be switched due the lack of efficacy or bad tolerance.

Methods: The study was a 12-week, open label, multicenter, non comparative trial on oral ziprasidone. 106 patients with DSM-IV schizophrenia were switched to ziprasidone from their previous antipsychotic without a washout phase.

Brain blood flow changes measured by positron emission tomography during an auditory cognitive task in healthy volunteers and in schizophrenic patients.

Objective: Cognitive deficit is an essential feature of schizophrenia. One of the generally used simple cognitive tasks to characterize specific cognitive dysfunctions is the auditory "oddball" paradigm. During this task, two different tones are presented with different repetition frequencies and the subject is asked to pay attention and to respond to the less frequent tone.

[Cognitive functions in prepsychotic and negative-symptom schizophrenic patients].

Background: Relationship between schizophrenia and cognitive functions has been reported by several studies. Our work group examined the changes of cognitive functions in prepsychotic patients without any relevant psychiatric disorder in their anamnesis, and also in schizophrenic patients with predominantly negative symptoms.

Methods: Measures were carried out by Cambridge Neuropsychological Test Automated Battery (CANTAB), a complex computer-based test battery of 13 tests covering a wide range of cognitive functions.

Cognitive functions in prepsychotic patients.

Objective: Cognitive dysfunctions are now widely understood as an essential feature of schizophrenia. A great number of cognitive disturbances have been described in drug-naive first-episode patients as well. The full-blown psychotic symptoms are usually preceded by a longer prodromal period, in which non-specific psychological disturbances are already present.

[Effect of atypical antipsychotics on metabolism].

The metabolic effect of atypical antipsychotic drugs may manifest itself in weight gain, disturbances in glucose homeostasis and dyslipidemia. One confounding factor is that psychotic disorders themselves make the patients prone to specific metabolic changes. Nevertheless clinical studies have confirmed that atypical anti-psychotic drugs have a different metabolic effect.

The role of cytochrome P450 enzymes in the metabolism of risperidone and its clinical relevance for drug interactions.

In the recent years it has been increasingly recognized that pharmacogenetical factors play an important role in the drug treatment. These factors may influence the appearance of side-effects and drug interactions due to interindividual differences in the activity of metabolizing enzymes. Risperidone in humans is mainly metabolized to 9-hydroxyrisperidone by the polymorphic cytochrome enzyme P450 2D6 (CYP2D6).

Relationship between risperidone and 9-hydroxy-risperidone plasma concentrations and CYP2D6 enzyme activity in psychiatric patients.

The implication of cytochrome P450 CYP2D6 enzyme activity in the metabolism of the antipsychotic drug risperidone has been reported in vitro and in studies of healthy volunteers. Around 7 % of Caucasians have inherited impaired capacity of this enzyme (poor metabolisers). These subjects might be prone to higher plasma concentrations of risperidone.

[Relationship between clozapine plasma levels and withdrawal symptoms].

Discontinuation of clozapine and an attempt to change his medication to sertindol has led to serious psychotic and somatic symptoms in an schizophrenic patient treated with clozapine for five years, however after readministration of clozapine these symptoms rapidly disappeared. To further analyse the case we have developed an HPLC method for the measurement of plasma levels of clozapine and its main metabolite N-desmethyl clozapine in order to monitor the plasma levels of clozapine and to correlate with the clinical symptoms. The present results confirmed that after discontinuation of clozapine no measurable amount of drug or its main metabolite were present in the plasma of the patient.

Serum paraoxonase activity changes in patients with Alzheimer's disease and vascular dementia.

The prevalence of Alzheimer's disease (AD) and vascular dementia (VAD) increases with aging of the population. The role of lipoproteins in the pathogenesis of AD is unclear: apoE(2) offers protection and apoE(3) is neutral, while apoE(4) promotes the development of the disease. Recently, several studies have confirmed the role of oxidative stress in the pathogenesis of AD and VAD.

[Auditory event related potential and PET scan: a possibility for the comprehensive evaluation of cognition].

The authors studied the parallel use of event related potential (ERP) and brain activation PET in nine healthy volunteers. The presence of P300 wave in the EEG recording was accompanied by a parallel increase in the blood perfusion of the anterior cingulate gyrus. Furthermore, the functional connectivity between cortical and subcortical structures was also present during the task.

[Use of positron emission tomography in psychiatry].

For the past years, substantial amount of experimental data has been published on the use of positron emission tomography in different psychiatric disorders. The different PET methods, which evaluate the whole-brain or regional metabolism, tissue perfusion or receptor density may help to identify the disorder specific changes in brain function and also better understand the underlying pathophysiology. In the clinical practice, PET plays an important role in the diagnosis and differential diagnosis of dementias and, presumably, in the near future the PET technique will be also extensively used in the clinical examination of other psychiatric disorders.

N(epsilon)(gamma-glutamyl)lysine in cerebrospinal fluid marks Alzheimer type and vascular dementia.

N(epsilon)(gamma-glutamyl)lysine isodipeptide is released from the breakdown of proteins cross-linked by transglutaminase enzymes. Transglutaminase activation is a marker of apoptosis and elevated isodipeptide concentrations in body fluids might correlate with the intensity of apoptotic cell turnover. The concentration of N(epsilon)(gamma-glutamyl)lysine was measured in the cerebrospinal fluid (CSF) of patients with probable Alzheimer's disease (n = 14) and vascular type dementia (n = 11) and compared with not demented surgical controls (n = 17).

Clozapine withdrawal symptoms after change to sertindole in a schizophrenic patient.

A 30-year-old male patient with paranoid schizophrenia was on clozapine therapy for more than five years. Discontinuation of clozapine and an attempt to change his medication to sertindole has led to serious psychotic and somatic symptoms. After readministration of clozapine the psychotic symptoms rapidly disappeared.

[First Hungarian experiences with positron emission tomography (PET) studies. Members of the PET working group].

Diagnostic investigations commenced on the 28th of June 1994 in Hungary's and Central Europe's first PET Centre at the University Medical School of Debrecen. The Centre is equipped with a GE 4096 Plus whole body PET scanner. A metabolic tracer, 18F-deoxy-D-glucose (FDG), was used in the investigations.

Ascorbic acid in cerebrospinal fluid - a possible protection against free radicals in the brain.

The function of ascorbic acid in living organisms is complex. Previous studies emphasize its protective role against harmful effect of free radicals, and its presence is necessary for the function of numerous enzymes. Ascorbic acid is a powerful reducing agent due to its dienol molecular structure, which is not present in the oxidized form, dehydroascorbic acid.

Concentration gradients for HVA, 5-HIAA, ascorbic acid, and uric acid in cerebrospinal fluid.

Concentrations of HVA, 5-HIAA, ascorbic acid, and uric acid in the lumbar and cisternal cerebrospinal fluid (CSF) were measured in psychiatric and neurologically impaired patients. The concentration of HVA is 6.1 times and of 5-HIAA 2.