Clinical Neuroscience

[THE ROLE OF CHRONIC BRAIN HYPOPERFUSION IN THE PATHOGENESIS OF ALZHEIMER'S DISEASE - FACTS AND HYPOTHES]

ZÁDORI Dénes, DATKI Zsolt, PENKE Botond

NOVEMBER 30, 2007

Clinical Neuroscience - 2007;60(11-12)

[In Alzheimer’s disease, which belongs to the neurodegenerative disorders, the ethiopathogenetic role of several risk factors has been proved. A considerable number of them are mainly known as cardiovascular risk factors and can precipitate chronic brain hypoperfusion. Using functional imaging techniques, this hypoperfusion and the resulting hypometabolism become detectable in the watershed areas of the brain as early as in the stage of mild cognitive impairment. Hypoperfusion leads to the degeneration of capillaries in this area causing the deterioration of diffusion. The further reduction of nutrient and oxygen support of neurons is capable to initiate a neurodegenerative process which spreads along the glutamaterg system arising from the neurons of the association cortices. The neuropathological lesions of this neuronal system, such as the neurofibrillary tangles and the β-amyloid plaques, are known to be the characteristic markers of Alzheimer's disease. In our review we present the development of hypoperfusion and its consequences in the watershed areas of the brain and describe the neurodegenerative process of the neuronal system arising from the neurons of the association cortices in the early stage of Alzheimer's disease. Considering the previous hypotheses and the neuropathological lesions of Alzheimer's disease we give a new consensus model to characterize the pathomechanism of the disorder.]

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[DIFFUSION TENSOR AND FUNCTIONAL MR IMAGING OF SEVERE TRAUMATIC BRAIN INJURY AT LOW MAGNETIC FIELD]

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[Aim of the study - Presentation of diffusion tensor imaging (DTI) performed at low magnetic field (1 Tesla) in the algorithm of work-up of a patient suffering from severe traumatic brain injury (TBI). Method - DTI and functional MRI (fMRI) were applied at 1 Tesla for visualization of neural pathways and examination of sensory functions of a patient with severe TBI. DTI-measurement was also performed on a healthy patient for comparison. Results - DTI acquired at low magnetic field yielded appropriate visualization of neural pathways. DTI confirmed the results of the clinical and fMRI examinations in the patient suffering from severe TBI. Conclusion - An optimized DTI can be useful in the examination of patients with TBI, moreover, it may also help in the establishment of diagnoses of other central nervous system diseases affecting neuronal pathways. The presented results suggest that DTI of appropriate quality can be performed at low magnetic field.]

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[CONGRESS CALENDAR]

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[acquired. The human prion protein gene (PRNP) is located to chromosome 20 (20p12-ter). Mutations and polymorphisms in the PRNP are associated with prion disease. Genetic prion diseases are inherited in an autosomal dominant trait, examination of the penetrance is restricted to mutation E200K (59-89%). Mutations can be substitutions or insertions. Genetic prion diseases are classified according to the clinicopathological phenotype and comprise genetic Creutzfeldt-Jakob disease, Gerstmann-Sträussler-Scheinker disease and fatal familial insomnia. Base pair insertions may resemble Creutzfeldt-Jakob disease or Gerstmann-Sträussler-Scheinker disease phenotypes, however, their unique clinicopathological presentations are also emphasized. Among the polymorphisms of the PRNP, the one at codon 129 is the most important, where methionine or valine may be encoded. This polymorphism is known to influence the phenotype of disease forms. Molecular classification of sporadic Creutzfeldt-Jakob disease also depends on the codon 129 polymorphisms in addition to the Western blot pattern of the protease resistant prion protein. According to this at least six well characterised forms of sporadic Creutzfeldt-Jakob disease are known. Influence of other genes were also investigated. Contrasting results are reported regarding the role of apolipoprotein E allele ε4, but presence of allele ε2 seems to influence the prognosis. Polymorphisms in the doppel gene or ADAM10 could not be clearly associated with Creutzfeldt-Jakob disease. Polymorphisms in the upstream and intronic regulatory region of the PRNP gene may be a risk factor for Creutzfeldt-Jakob disease. The PRNP codon 129 polymorphism was examined in non-prion diseases. Some studies suggest that this polymorphism may have influence on the cognitive decline and early onset Alzheimer’s disease.]

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[Stress, depending on its level and quality, may cause adaptive and maladaptive alterations in brain functioning. As one of its multiple effects, elevated blood cortisol levels decrease the synthesis of the neuroprotective BDNF, thus leading to hippocampal atrophy and synapse loss, and rendering it a possible cause for the Alzheimer’s disease (AD) related neuropathological and cognitive changes. As a result of the stress response, intraneuronal alterations - also affecting the metabolism of β-actin - can develop. These have a role in the regulation of memory formation (LTP), but in pathological conditions (AD) they could lead to the accumulation of Hirano bodies (actin-cofilin rods). According to the dementia treatment guidelines, the behavioural and psychological symptoms of AD can be treated with certain antipsychotics. Therefore, the aim of our study was to examine the effects of sertindole (currently not used in the standard management of AD) on the transcription of some AD associated genes (amyloid precursor protein [APP], mitogen activated protein kinase-1 [MAPK-1], β-actin) in the brain of rats exposed to chronic immobilization stress (CIS). Male Wistar rats were exposed to CIS for three weeks. The four groups were: control (n=16), CIS (n=10), 10 mg/kg sertindole (n=5) and 10 mg/kg sertindole + CIS (n=4). Following transcardial perfusion, the relative levels of hippocampal and cortical mRNA of the previously mentioned genes were measured with real-time PCR. CIS induced hippocampal β-actin (p<0.01), MAPK-1 and APP (p<0.05) mRNA overexpression. The simultaneous administration of sertindole suppressed this increase in β-actin, MAPK-1 and APP expression (p<0.05). Ours is the first report about CIS induced β-actin gene overexpression. This finding, in accordance with the similar results in APP and MAPK-1 expression, underlines the significance of cytoskeletal alterations in AD pathogenesis. The gene expression reducing effect of sertindole suggests that antipsychotic drugs may have a neuroprotective effect.]

Clinical Neuroscience

[Epidemiology of dementia in Hungary]

ÉRSEK Katalin, KÁRPÁTI Krisztián, KOVÁCS Tibor, CSILLIK Gabriella, GULÁCSI L. Ádám, GULÁCSI László

[Objective - To estimate the epidemiology and the distribution of disease severity of dementia in Hungary, using published data. To estimate the demented population of 2008 and to make a projection for 2050. Methodology - With an outlook for the international professional literature and the available Hungarian information we examine the epidemiology of dementia in Hungary by age-groups and disease severity (according to MMSE categories), then make our estimation for the entire population. Results - Based on the estimation of the number of demented people in Hungary there is a noticeable difference between the domestic and the internationally published data. According to previous Hungarian studies, the number of the demented subjects vary between 530 and 917 thousand patients. Multiplying the elderly age-group’s populations by the global prevalence data it results in 101 thousand of demented patients. Estimation by the domestic published data we remarkably overestimate the presumed value, whereas by using the global prevalence figures we underestimate. Conclusions - There is a strong need for a representative study to obtain exact figures on the prevalence of dementia in Hungary. Getting exact figures of the Hungarian prevalence of dementia it is a strong need an overall representative study. With the lack of it the health and social care systems are not able to prepare for providing the increasing number of patients.]