Clinical Neuroscience

[The role of β-amyloid and mitochondrial dysfunction in the pathogenesis of Alzheimer’s disease]

SZARKA András

JULY 30, 2015

Clinical Neuroscience - 2015;68(07-08)

DOI: https://doi.org/10.18071/isz.68.0222

[Alzheimer’s disease is the most common form of dementia in mid- and late life. The 7-10% of the population over 65 and the 50-60% of the population over 85 are affected by this disease. On the contrary of its prevalence the pathogenesis of the disease is not well defined and there is no effective neuroprotective therapeutic agent. Three predominant neuropathological features of the Alzheimer’s disease brain are intracellular neurofibrillary tangles consisting mainly of the hyperphosphorylated protein t; the extracellular amyloid deposits (neuritic plaques) consisting of amyloid b peptide; and the extensive neuronal cell loss in the hippocampus and in portions of the cerebral cortex. The possible reason of the extensive neuronal cell loss can be the mitochondrial dysfunction observed in Alzheimer’s disease. Beyond the unclarified pathogenesis the causality of these characteristic neuropathologic phenomena are still unknown. In this study we would like to deal with two actual hypotheses, with the amyloid cascade and with the mitochondrial cascade hypotheses. We try to give an overview of these two hypotheses and to depict their interrelationship.]

COMMENTS

0 comments

Further articles in this publication

Clinical Neuroscience

Mental health of physicians - nationwide representative study from Hungary

GYŐRFFY Zsuzsa, GIRASEK Edmond

Background and aim - Somatic and mental health and stress factors of physicians became an issue of growing interest in both national and international researches. Our aim is to give an overviewing analysis of Hungarian physicians’ mental health state. Methods - Representative, cross-sectional, quantitative survey on a representative sample of Hungarian physicians (n=4784). The control group was formed by the population group of a national survey conducted by “Hungarostudy 2013” (n=2000). Results - Suicidal thoughts (18.8% vs. 9.6%, p<0.001), the scores of Somatic Symptom Scale (PHQ-10, 20.4% vs. 13.6%, p<0.001) were significantly higher among physicians. The suicidal attempts (1.9% vs. 3.5%, p=0.053) and BDI depression scores (7.9% vs. 29.5%, p<0.001) were significantly higher in the control group. High Perceived Stress Scale (PPS) scores occurred in 43.3% of the physicians sample, and 43.4% of them had high scores in the Athenian Insomnia Scale (AIS). The young (<35) female physicians showed significantly higher rates of suicidal thoughts, higher scores of PHQ and PPS. In the young female cohort, the AIS scores were significantly higher than of the other physicians. Conclusions - Mental health of physicians (sleep disorders, suicidal thoughts and psychosomatic symptoms) showed poorer results than the population data. BDI scores and the rate of suicidal attempts showed favourable trends. The next step in the physicians’ mental health researches is to investigate the most decisive risk factors, and to work out the prevention tools.

Clinical Neuroscience

[Focal motor seizures and status epilepticus provoked by mirtazapine]

DÖMÖTÖR Johanna, CLEMENS Béla

[The seizure-provoking effect of the tetracyclic antidepressant mirtazapine is not a well-known adverse effect of the drug. The authors report on a 39-year-old non-epileptic patient who had been treated for depression with the usual daily dose of mirtazapine. Having increased the daily dose of the drug from 30 to 45 milligrams he experienced a few clonic seizures of the right lower limb. This symptom and insomnia erroneously intended the patient to further increase the daily dose of mirtazapine, which immediately resulted in the evolution of focal clonic status epilepticus in the same limb. After admission, this condition was recorded by video-EEG and abolished by intravenous administration of levetiracetam after the intravenous clonazepam had been ineffective. Discontinuation of mirtazapine and administration of carbamazepine resulted in completely seizure-free state that persisted even after carbamazepine treatment was terminated. The clinical and laboratory data indicate the seizure-provoking effect of mirtazapine in the reported case.]

Clinical Neuroscience

[Radiosurgery of intracerebral cavernomas - Current Hungarian practice]

FEDORCSÁK Imre, NAGY Gábor, DOBAI József Gábor, MEZEY Géza, BOGNÁR László

[Background and purpose - Radiosurgery is an increasingly popular treatment option especially for deep eloquent intracerebral cavernomas that are often too risky for surgical removal, but their re-bleed carries significant risk for persisting neurological deficit. Gamma-radiation based radiosurgery has been being available since 2007 in Hungary in Debrecen. Our aim is to summarize our experience accumulated during the first five years of treatment and to compare it to the international experience. Patient selection and methods - We retrospectively analyzed 51 cavernomas in 45 patients treated between 2008 and 2012 in terms of localization, natural history, and the effect of radiosurgery on re-bleed risk and epilepsy, and its side effects. Results - We treated 26.5% deep eloquent (brainstem, thalamic/basal ganglia) and 72.5% superficial hemispheric cavernomas. The median presentation age was 25 years (13-60) for deep, and 45 years (6-67) for superficial cavernomas. They were treated median of 1 year after presentation. 64.5% of deep cavernomas bled before treatment, the annual risk of first hemorrhage was 2%/lesion, re-bleed risk 21.7%, with 44% persisting morbidity. 13.5% of superficial cavernomas bled prior to treatment, the risk of first bleed was 0.3%, there was no re-bleed, and 35% caused epilepsy. We used GammaART-6000TM rotating gamma system for treatment, marginal dose was 14 Gy (10-16), and treatment volume 1.38-1.53 cm3. Re-bleed risk of deep eloquent lesions fell to 4% during the first two years after treatment and to 0% thereafter, and no hemorrhage occurred from superficial lesions after treatment. Persisting morbidity in deep lesions came from adverse radiation effect in 7% and from re-bleed in 7%, and there was no persisting side effect in superficial cavernomas. 87.5% of cases of epilepsy resistant to medical therapy improved. Radiological regression was found in 37.5% and progression in 2% after treatment. Conclusions - Radiosurgery of cavernomas is safe and effective. Early preventive treatment for deep cavernomas carrying high surgical risk is justified. Moreover, for superficial lesions that are surgically easily accessible radiosurgery also appears to be an attractive alternative.]

Clinical Neuroscience

Thrombocytopenia with gabapentin usage

ATAKLI Dilek, YUKSEL Burcu, AK Dogan Pelin, SARIAHMETOGLU Hande, SARI Hüseyin

Gabapentin is an antiepileptic drug approved for adjunctive therapy for partial seizures. We report a case of a patient who had thrombocytopenia with the dose of 2400 mg/day of gabapentin. The causal relationship between gabapentin and thrombocytopenia was revealed by dramatic increase in thrombocyte count following the cessation of the gabapentin treatment. To our knowledge, this is the first case report with a hematopoietic side effect of gabapentin.

Clinical Neuroscience

[LGI1 encephalitis: the first Hungarian patient]

SZŐTS Mónika, MARTON Annamária, ILLÉS Zsolt, BAJZIK Gábor, NAGY Ferenc

[In the recent years, it has been increasingly recognised that in a group of limbic encephalitis antibodies are directed against the scaffolding protein LGI1 (Leucine-rich glioma inactivated 1), which is part of the voltage gated potassium channel (VGKC) complex on neural synapses. Patients present with seizures and subacute history of neuropsychiatric symptoms, including psychosis and changes in memory, cognition, behaviour. Faciobrachial dystonic seizures can be observed, which are highly characteristic for LGI1 encephalitis. MRI shows medial temporal abnormalities in more than half of the cases. CSF evaluation is usually normal. Hyponatremia is frequently associated and may confuse the initial diagnosis. Early recognition and prompt initiation of immunotherapies are of great importance. The clinical improvements often correlate with the antibody levels. We present the case of a 64-year old man, who responded quickly to plasma exchange and major improvement was noted within few weeks.]

All articles in the issue

Related contents

Clinical Neuroscience

[Frontotemporal dementia - Part II Differential diagnosis, genetics, molecular pathomechanism and pathology]

GALARIOTIS Vasilis, BÓDI Nikoletta, JANKA Zoltán, KÁLMÁN János

[This is a comprehensive paper in three parts covering history, prevalence, clinical forms, differential diagnosis, genetics, molecular pathomechanism, pathology, clinical diagnosis and treatment of frontotemporal dementia (FTD). The second part focuses on the differential diagnosis, genetics, molecular pathomechanism and pathology. The clinical diagnosis of frontotemporal dementia is based on the presence of a prominent disturbance of the executive function and of frontal lobe syndrome or a progressive aphasic syndrome without severe global cognitive impairment. Of other dementias, it is primarily Alzheimer’s disease that it should be differentiated from, but other psychiatric disorders must also be ruled out. The disease has familial and sporadic forms. Recent identification of mutations in the gene encoding the microtubule-associated tau protein in the inherited frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) has demonstrated that various tau dysfunctions can lead to neurodegeneration. Tau gene mutations have varied effects on the biology and function of the protein. This heterogeneous pathomechanism explains the wide range of clinical and neuropathological features observed in the FTDP-17. Tau and ubiquitin antibodies can be detected by sensitive immunohistochemical methods. The diagnosis of FTD should be based on neuropathological examination, and this is also the only method by which it can be definitely differentiated from other types of dementias.]

Lege Artis Medicinae

[The effects of angiotensin receptor blockers on the nervous system in hypertension and dementia]

KOVÁCS Tibor

[The renin-angiotensin system (RAS) is one of the most important mechanisms regarding the pathomechanism and treatment of hyprtension. The most of the elements of the RAS are found in the nervous system too. The effect of angiotensin converting enzyme inhibitors and angiotensin receptor blockers (ARBs) is based on the inhibition of the RAS. ARBs might have a special role in the central nervous system because they do not decrease the production of angiotensin but inhibit its harmful effects mediated through the AT1 receptor while allowing the stimulation of AT2 receptors with resulting pleiotrophic actions. Hypertension is the most important risk factor for stroke and has a negative effect on cognitive functions. Antihypertensive treatment has an effect on the nervous system; in addition to the consequences of the reduced blood pressure, ARBs might provide additional advantages in stroke and dementia prevention.]

Clinical Neuroscience

[The effect of angiotensin receptor blockers in cerebrovascular disorders and dementia: Bonus in addition to the antihypertensive effect]

KOVÁCS Tibor

[Hypertension and dementia are frequent disorders or rather syndromes. Their incidence is growing with advancing age and hypertension is increasing the risk of cognitive impairment too, while treating hypertension (i.e. the use of antihypertensive medications) is decreasing it. In addition, hypertension is the most important risk factor for stroke. The renin-angiotensin system (RAS) has a special role in the development of hypertension and also involved in the pathogenesis of the most frequent dementia form, namely Alzheimer’s disease. The effect of angiotensin convertase inhibitors and angiotensin receptor blockers (ARB) is based on the inhibition of the RAS, but the ARBs do not inhibit angiotensin formation, just blocking its harmful effects on the AT1 receptor, while allowing the activation of AT2 receptors with pleiotropic effects. Preclinical, epidemiological and clinical therapeutic studies suggest this additional effect of ARBs and these are summarized in this review.]

Clinical Neuroscience

[The role of immobilization stress and sertindole on the expression of APP, MAPK-1 and β-actin genes in rat brain]

KÁLMÁN János, PÁKÁSKI Magdolna, SZŰCS Szabina, KÁLMÁN Sára, FAZEKAS Örsike, SÁNTHA Petra, SZABÓ Gyula, JANKA Zoltán

[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.]