2013 International Congress on Vascular Dementia (Guest Editor: Amos D. Korczyn)
Amos D. Korczyn
International Congress on Vascular Dementia, Athens, Greece, 17-20 October 2013
Vassiliki Rentoumi, Ladan Raoufian, Samrah Ahmed, Celeste A. de Jager, Peter Garrard
Features and Machine Learning Classification of Connected Speech Samples from Patients with Autopsy Proven Alzheimer's Disease with and without Additional Vascular Pathology
Abstract: Mixed vascular and Alzheimer-type dementia and pure Alzheimer’s disease are both associated with changes in spoken language. These changes have, however, seldom been subjected to systematic comparison. In the present study, we analyzed language samples obtained during the course of a longitudinal clinical study from patients in whom one or other pathology was verified at postmortem. The aims of the study were twofold: first, to confirm the presence of differences in language produced by members of the two groups using quantitative methods of evaluation; and secondly to ascertain the most informative sources of variation between the groups. We adopted a computational approach to evaluate digitized transcripts of connected speech along a range of language-related dimensions. We then used machine learning text classification to assign the samples to one of the two pathological groups on the basis of these features. The classifiers' accuracies were tested using simple lexical features, syntactic features, and more complex statistical and information theory characteristics. Maximum accuracy was achieved when word occurrences and frequencies alone were used. Features based on syntactic and lexical complexity yielded lower discrimination scores, but all combinations of features showed significantly better performance than a baseline condition in which every transcript was assigned randomly to one of the two classes. The classification results illustrate the word content specific differences in the spoken language of the two groups. In addition, those with mixed pathology were found to exhibit a marked reduction in lexical variation and complexity compared to their pure AD counterparts.
Effectiveness and Cost-Effectiveness of the Pharmacological Treatment of Alzheimer’s Disease and Vascular Dementia
Abstract: Until an effective and especially disease-modifying treatment for Alzheimer’s disease (AD) and vascular dementia (VaD) is available, the currently available pharmacological therapeutic arsenal aims at merely improving symptomatology. Health economic data make an important contribution to the planning of healthcare services and the estimation of the cost of drug reimbursement. As such, both for cholinesterase inhibitors and, to a lesser extent, for memantine it can be claimed that the direct cost of the drug itself is eclipsed by the cost savings associated with delaying institutionalization or delaying the time of progression into a more severe disease state. The present manuscript reviews several factors contributing to the costs of dementia, gives an overview of available studies claiming both the effectiveness and cost-effectiveness of current dementia treatments, and highlights strengths and weaknesses of the aforementioned studies.
Ilaria Di Donato, Maria Teresa Dotti, Antonio Federico
Update on Several/Certain Adult-Onset Genetic Leukoencephalopathies: Clinical Signs and Molecular Confirmation
Abstract: Adult-onset leukoencephalopathies are clinically and pathologically heterogeneous diseases, characterized by overlapping clinical and neuroradiological features and a difficult diagnostic process. Nevertheless, knowledge of the metabolic and genetic basis of leukoencephalopathies is constantly increasing. This article provides an overview of currently known leukoencephalopathies in adulthood, emphasizing, in addition to the classical forms, their atypical clinical presentations. In particular, we review the clinical spectrum and the molecular pathogenesis of certain adult-onset leukoencephalopathies, including cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL), cerebroretinal microangiopathy with calcifications and cysts (CRMCC), hereditary diffuse leukoencephalopathy with spheroids (HDLS), fragile X-associated tremor/ataxia syndrome (FXTAS), vanishing white matter disease (VWM), autosomal dominant leukodystrophy due to lamin B1 duplication (ADLD), and vascular leukoencephalopathy mapping to chromosome 20q13.
Aleksandra M. Pavlovic, Tatjana Pekmezovic, Gordana Tomic, Jasna Zidverc Trajkovic, Nada Sternic
Baseline Predictors of Cognitive Decline in Patients with Cerebral Small Vessel Disease
Abstract: Introduction. Cerebral small vessel disease (SVD) is a common cause of cognitive impairment and vascular dementia. Objective. We aimed to investigate predictors of cognitive decline in patients with SVD who initially presented with first-ever small subcortical stroke of lacunar type but had normal cognitive status. Methods. A total of 294 patients with SVD were evaluated 3-5 years after initial presentation. We analyzed baseline demographic data, vascular risk factors, functional status expressed as score on modified Rankin Scale, total number of lacunar infarcts, and severity of white matter hyperintensities (WMH) on magnetic resonance imaging with Age-Related White Matter Changes scale total score (tARWMC) and Fazekas scale periventricular and deep subcortical scores. Results. At follow-up, vascular cognitive impairment (VCI) on any type was detected in 188 (63.9%) of SVD patients, with 65 (22.1%) meeting criteria for vascular dementia and 123 (41.8%) presenting with cognitive impairment not dementia. Patients with VCI were older (64.4±10.3 in VCI versus 58.6±10.5 years in non-VCI; p<0.0001) at the time of initial clinical presentation and more frequently male (57.9% VCI versus 46.2% non-VCI; p=0.052). No difference was noted in frequency of vascular risk factors in VCI versus non-VCI cases. Multivariate logistic regression analysis adjusted by age and gender identified overall severity of WMH (tARWMC HR 1.42, 95%CI 1.01–2.00; p0.043) and total number of lacunar infarcts (HR 3.06, 95%CI 1.71-5.50, p<0.001) as independent predictors of cognitive decline. Conclusion. In patients with SVD, independent predictors of VCI were baseline severity of WMH and total number of lacunar infarcts.
Olga A. Trubnikova, Anastasia S. Mamontova, Irina D. Syrova, Olga V. Maleva, Olga L. Barbarash
Does Preoperative Mild Cognitive Impairment Predict Postoperative Cognitive Dysfunction after On-Pump Coronary Bypass Surgery?
Abstract: Background: Mild cognitive impairment (MCI) may contribute to the development of postoperative cognitive dysfunction (POCD) after coronary artery bypass grafting (CABG). Objective: The aim of this study was to investigate the incidence of early and long-term POCD after CABG in coronary heart disease patients with and without preoperative MCI. Methods: The study enrolled two groups of males with coronary heart disease: 51 without MCI (mean age 56.0±6.42 years) and 50 with MCI (mean age 56.4±5.55 years). Baseline clinical characteristics as well as durations of cardiopulmonary bypass and aortic cross-clamping were similar between the two groups. MCI was defined as a Mini–Mental State Examination score of less than 28. All patients underwent detailed neuropsychological examinations (12 tests) before and 7–10 days and 1 year after surgery. The incidence of early and long-term POCD was estimated on the basis of criteria defined as a 20% decline on 20% of the tests. Results: Early POCD was diagnosed in 72% of cases in patients with MCI and in 79% of those without MCI (p = 0.5; odds ratio [OR] = 0.68; 95% confidence interval [CI] 0.2–2.2). Long-term POCD was diagnosed in 72% of MCI patients and in 70% of non-MCI patients (p = 0.8); OR = 1.08 (95% CI 0.4–2.9). Conclusions: Our results show that the presence of MCI is not the leading cause of either early or long-term POCD in patients undergoing CABG. Further research should focus on the contribution of important clinical factors, including progression of atherosclerosis and adherence, to post-CABG POCD.
Christophe E. Graf, Cécile Rossi, Sandra V. Giannelli, Bentolhoda Heyrani Nobari, Gabriel Gold, François R. Herrmann, Dina Zekry
Vitamin D is not associated with Cognitive Status in a Cohort of Very Old Hospitalized Patients
Abstract: Background/Objective: The association between vitamin D levels and cognitive function remains a controversial issue especially in the very old, highly comorbid patients. We address the relative contribution of vitamin D when taking into account potential confounders well known to be involved in cognitive decline. Methods: We investigated, in a prospective study of 428 very old inpatients from the Geneva geriatric hospital (mean age 85.2y ±6.8; 74.1% women), the association between 25-hydroxyvitamin D (25(OH)D) levels with dementia and mild cognitive impairment (MCI), taking into account comorbid conditions, functionality, malnutrition, ApoE genotype, vitamin B12, calcium, and albumin as independent variables. Results: 25(OH)D level was not different between the cognitively normal (n=200), MCI (n=46), and demented (n=182) patients nor between the different etiologies of dementia. In polytomous logistic regression, the 25(OH)D level neither as a continuous variable nor as a categorical variable increased the risk to be MCI or demented. The 25(OH)D level did not predict conversion from normal or MCI to dementia in the 315 subjects who completed the 2 years follow-up. No changes were observed in the full adjusted model after taking into account the independent variables. Similarly, considering only the group of cognitively normal subjects, the 25(OH)D level was not associated with impairment of specific cognitive domain. Conclusion: In this cohort of old hospitalized patients with a high burden of comorbidities, the 25(OH)D level alone or adjusted for confounders is not associated with cognitive status and did not predict conversion to dementia.
David G. Bruce, Wendy A. Davis, Sergio E. Starkstein, Timothy M. Davis
Mid-Life Predictors of Cognitive Impairment and Dementia in Type 2 Diabetes Mellitus: The Fremantle Diabetes Study
Abstract: Background: The pathway linking type 2 diabetes and cognitive disorders remains poorly understood, and there are many potential risk factors. Objective: To conduct a longitudinal study of risk factors in middle-aged patients with type 2 diabetes. Methods: Type 2 patients from the Fremantle Diabetes Study underwent comprehensive assessment of risk factors in 1993/1996 and cognitive assessment in 2008/2010. After a cognitive screen (Mini-Mental State Examination), the Clinical Dementia Rating was used to define cognitive impairment (rating 0.5) and dementia. The methodology was similar to a previous report in older patients from the same cohort permitting comparison with that study. Results: Of 335 eligible survivors, aged 57.5±9.2 years at baseline and 72.2±9.1 years at cognitive assessment, 14.7±1.1 years later, 276 were cognitively normal, 27 had cognitive impairment, 17 had dementia, and 15 were unclassifiable. Independent, baseline predictors of dementia were age, poorer education, and cigarette smoking. Predictors of cognitive impairment included insulin therapy and fasting glucose (negative association), while diabetic retinopathy was an additional predictor of cognitive impairment and dementia combined. Conclusion: This study identified diabetes-specific risk factors, insulin therapy and diabetic retinopathy, that may explain the excess risk for cognitive disorders in type 2 diabetes. These risk factors differed from a previous report in older patients and the main difference appears to be related to duration of diabetes in the respective samples. The duration of diabetes or its manifestations is an important determinant of the impact of diabetes on cognitive disorders. Smoking is another important modifiable risk factor.
Costas A. Anastasiou, Mary Yannakoulia, Nikolaos Scarmeas
Vitamin D and Cognition: An Update of the Current Evidence
Abstract: The active form vitamin D is a seco-steroid with multiple neurotrophic and neuroprotective functions in the central nervous system. Robust evidence from studies in animals suggests that vitamin D deficiency may impair brain physiological functioning causing anatomical and behavioral adverse effects. On the other hand, vitamin D has been found to be protective against biological processes associated with Alzheimer’s disease and cognition, including amyloid-β deposition, inflammation, calcium homeostasis, and corticosteroid-induced perturbations in cortical areas and the hippocampus. Human studies that examined the relationship between vitamin D status and cognitive function have provided inconclusive results. The majority of cross-sectional and longitudinal studies suggest a potentially protective association, whereas results from clinical trials are mostly negative, or at best, controversial. We review these studies in humans, with particular emphasis on randomized and observational prospective ones.
Martin Vyhnalek, Tomas Nikolai, Ross Andel, Zuzana Nedelska, Eva Rubínová, Hana Marková, Jan Laczó, Ondrej Bezdicek, Katerina Sheardova, Jakub Hort
Neuropsychological Correlates of Hippocampal Atrophy in Memory Testing in Nondemented Older Adults
Abstract: Background and Objective: Cognitive deficits in older adults attributable to Alzheimer's disease (AD) pathology are featured early on by hippocampal impairment. Among tests used to evaluate memory, verbal memory tests with controlled encoding and cued recall are believed to be specific for hippocampal impairment. The objective of this study was to assess the relation between left and right hippocampal volumes and several frequently used memory tests. Methods: Fifty six nondemented older adults (30 with amnestic mild cognitive impairment and 26 cognitively healthy older adults) underwent neuropsychological testing including: 1) The Enhanced Cued Recall test (ECR), a memory test with controlled encoding and recall; 2) the Auditory Verbal Learning Test (AVLT), a verbal memory test without controlled encoding and with delayed recall; and 3) The Rey-Osterrieth Complex Figure test (ROCF), a visuospatial memory test–recall condition. 1.5T brain MRI scans were used to measure estimated total intracranial volume (eTIV) along with hippocampal right and left volumes, which were measured with quantitative volumetry using FreeSurfer package (version 4.4.0). Spearman partial correlation controlled for age was used to correct for non-normal score distribution and effect of age. Results: We found moderate correlations of hippocampal volumes with AVLT 1–5 scores, AVLT delayed recall, ECR free and total recall, and ROCF reproduction. Total recall in ECR using cued recall was not superior to any of the free recall tests. No correlation in any memory test was achieved with eTIV. Conclusion: Verbal memory tests, either with controlled encoding and cued delayed recall (ECR), or without it (AVLT), as well as nonverbal memory test with delayed recall (ROCF), equally reflect hippocampal atrophy in nondemented older adults.
Zdena Kristofikova, Jan Ricny, Michaela Kolarova, Martin Vyhnalek, Jakub Hort, Jan Laczo, Jana Sirova, Daniela Ripova
Interactions between Amyloid-β and Tau in Cerebrospinal Fluid of People with Mild Cognitive Impairment and Alzheimer’s Disease
Abstract: Background: Despite the physiological sequestration of amyloid-β (Aβ) peptides by various carriers, interactions between peptides and protein tau appear to be pathological and involved in the development of Alzheimer’s disease (AD). A recent study reported increased Aβ-tau interactions in the neurons of AD patients. Objective: We investigated the possibility that levels of Aβ-tau complexes in cerebrospinal fluid could be a prospective biomarker of AD, with greater sensitivity and specificity than Aβ1-42, tau, or phospho-tau individually. Methods: By means of ELISA, we estimated levels of the complexes in 161 people (non-demented controls, people with mild cognitive impairment (MCI), probable AD or other types of dementia). Results: We found significant reductions in levels in people with MCI due to AD (down to 84.5%) or with AD (down to 80.5%) but not in other types of dementia. The sensitivity of the new biomarker to AD was 68.6%, the specificity 73.3% (compared to controls) or 59.1-66.1% (compared to other types of dementia). No significant correlations were observed between the complexes and the remaining biomarkers or between those and Mini-Mental State Examination score. Conclusion: We suppose that attenuated levels of complexes in cerebrospinal fluid reflect the accumulation of Aβ bound to tau in AD neurons and that changes start many years before symptom onset, analogously to those in Aβ1-42, tau, or phospho-tau. Unfortunately, these complexes are not a significantly better biomarker of AD than current biomarkers.
Jan Dörr*, Marius Ringelstein*, Thomas, Duning, Ilka Kleffner for the European Susac Consortium (EUSAC) *These authors contributed equally to this work.
Update on Susac Syndrome: New Insights in Brain and Retinal Imaging and Treatment Options
Abstract: Susac syndrome (SuS) is a rare endotheliopathy of the brain, the retina, and the inner ear. The underlying pathophysiology is likely an autoimmune mediated occlusion of microvessels resulting in variable degrees of central nervous system (CNS) dysfunction, visual disturbances, and hearing loss. The disease manifests either with a monophasic or polycyclic course. Patients suffering from SuS are frequently misdiagnosed as having inflammatory demyelinating CNS disease, particularly multiple sclerosis because of some overlap in the clinical presentation and the paraclinical findings. Since appropriate treatment of SuS is crucial for the prognosis, a timely and sound establishment of the diagnosis is important. Here, we summarize currently available information on the clinical presentation and diagnostic procedures in SuS. In particular, we discuss the added value of advanced techniques of brain and retinal imaging such as ultrahigh field magnetic resonance imaging and optical coherence tomography in SuS with respect to its differential diagnosis and pathophysiology. Since evidence-based treatment standards will not be available in the near future, we share some experiences in terms of treatment options. Finally, we briefly outline future areas of research in SuS.
Lieza G. Exalto, Geert Jan Biessels , Andrew J. Karter, Elbert S. Huang, Charles P. Quesenberry Jr, Rachel A. Whitmer
Severe Diabetic Retinal Disease and Dementia Risk in Type 2 Diabetes
Abstract: Background: Persons with type 2 diabetes are at an increased risk of dementia compared to those without, but the etiology of this increased risk is unclear. Objective: Cerebral microvascular disease may mediate the link between diabetes and dementia. Given the anatomical and physiological similarities between cerebral and retinal microvessels, we examined the longitudinal association between diabetic retinal disease and dementia in patients with type 2 diabetes. Methods: Longitudinal cohort study of 29,961 patients with type 2 diabetes aged ≥60 years. Electronic medical records were used to collect diagnoses and treatment of severe diabetic retinal disease (i.e., diabetic proliferative retinopathy and macular edema) between 1996-1998 and dementia diagnoses for the next ten years (1998-2008). The association between diabetic retinal disease and dementia was evaluated by Cox proportional hazard models adjusted for sociodemographics, as well as diabetes-specific (e.g., diabetes duration, pharmacotherapy, HbA1c, hypoglycemia, hyperglycemia) and vascular (e.g., vascular disease, smoking, body mass index) factors. Results: 2,008 (6.8%) patients had severe diabetic retinal disease at baseline and 5,173 (17.3%) participants were diagnosed with dementia during follow-up. Those with diabetic retinal disease had a 42% increased risk of incident dementia (demographics adjusted Hazards Ratio (HR)=1.42, 95% Confidence Interval (CI) 1.27, 1.58); further adjustment for diabetes-specific (HR1.29; 95%CI 1.14,1.45) and vascular-related disease conditions (HR 1.35; 95%CI 1.21,1.52) attenuated the relation slightly. Conclusion: Diabetic patients with severe diabetic retinal disease have an increased risk of dementia. This may reflect a causal link between microvascular disease and dementia.
Marjukka Bartelet, Wim Waterink, Susan van Hooren
Extreme Sexual Behavior in Dementia as a Specific Manifestation of Disinhibition
Abstract: In nursing homes, extreme sexual behavior is one of the most challenging behaviors in dementia. Despite this, however, there is no conformity in the literature regarding how to label and define this type of behavior. Examples of labels used include inappropriate sexual behavior, improper sexual behavior, sexually disinhibited behavior, or hyper sexuality. According to recent theoretical perspectives, extreme sexual behavior may be regarded as a part of disinhibited behavior or could be considered as an independent neuropsychiatric symptom. In this multicenter study, it was investigated whether there is a relationship between extreme sexual behavior and the typical neuropsychiatric symptoms seen in dementia. In 179 residents diagnosed with dementia, extreme sexual behavior was measured using an observation scale. Twelve neuropsychiatric symptoms were measured by the Neuropsychiatric Inventory. Multivariate analysis of covariance with gender showed that residents with observed extreme sexual behavior (n=43) only showed a higher score on neuropsychiatric symptom ‘disinhibition’, as compared to residents with non-observed sexual behavior (n=136). In addition, the effect size was large. These findings indicate that among residents with dementia, extreme sexual behaviors should not be considered as an independent neuropsychiatric symptom. Instead, disinhibition may be an important underlying mechanism for extreme sexual behavior and thus validates the label ‘sexually disinhibited behavior’.
Elena Radi, Patrizia Formichi, Carla Battisti, Antonio Federico
Apoptosis and Oxidative Stress in Neurodegenerative Diseases
Abstract: Neurodegenerative disorders affect almost 30 million individuals leading to disability and death. These disorders are characterized by pathological changes in disease-specific areas of the brain and degeneration of distinct neuron subsets. Despite the differences in clinical manifestations and neuronal vulnerability, the pathological processes appear similar, suggesting common neurodegenerative pathways. Apoptosis seems to play a key role in the progression of several neurologic disorders like Alzheimer’s disease, Parkinson's disease, Huntington’s disease, and amyotrophic lateral sclerosis as demonstrated by studies on animal models and cell lines. On the other hand, research on human brains reported contradictory results. However, many dying neurons have been detected in autoptic brains of patients with neurodegenerative diseases, and these conditions are often associated with significant cell loss accompanied by typical morphological features of apoptosis such as chromatin condensation, DNA fragmentation, and activation of cysteine-proteases called caspases. Cell death and neurodegenerative conditions have been linked to oxidative stress and imbalance between generation of free radicals and antioxidant defenses. Multiple sclerosis, stroke, and neurodegenerative diseases have been associated with reactive oxygen species and nitric oxide. Here we present an overview of the involvement of neuronal apoptosis and oxidative stress in the most important neurodegenerative diseases, mainly focusing the attention on several genetic disorders, discussing the interaction between primary genetic abnormalities and the apoptotic pathways.
Stavros J. Baloyannis
Golgi Apparatus and Protein Trafficking in Alzheimer’s Disease
Abstract: Alzheimer’s disease (AD) is a progressive degeneration of the brain, inducing memory decline, inability in learning, and behavioral alterations, resulting progressively in a marked deterioration of all mental activities and eventually a vegetative state. The main causative factor, however, is still unclear. The implication of amyloid-β, AβPP, tau protein, the selective loss of neurons, the alteration of the synapses, the cytoskeletal changes, and the morphological alterations of the brain capillaries contribute substantially to the pathogenetic profile of the disease, without sufficiently enlightening the initial steps of the pathological procedures. The ultrastructure of the neuronal organelles as well as histochemical studies revealed substantial alterations, primarily concerning mitochondria. In this study, the morphological and morphometric alterations of the Golgi apparatus (GA) are described in the Purkinje cells of the cerebellum in twenty AD brains, studied with electron microscopy. As it is well established, GA has a very important role to play in many procedures such as glycosylation, sulfation, and proteolysis of protein systems, which are synthesized in the endoplasmic reticulum of nerve cells and glia. GA may also play a crucial role in protein trafficking and in misfolding of protein aggregates. In addition, the hyperphosphorylation of tau protein is closely related with the pathology of GA. In AD cases, described in this study, an obvious fragmentation of the cisternae of GA was observed in the Purkinje cells of the vermis and the cerebellar hemispheres. This alteration of GA may be associated with alterations of microtubules, impaired protein trafficking, and dendritic, spinal, and synaptic pathology, since protein trafficking plays an essential role in the three dimensional organization of the dendritic arbor and in the integrity of the synaptic components.
Euphrosyni Koutsouraki, Eleni Hatzifilippou, Dimitrios Michmizos, Tania Banaki, Vassiliki Costa, Stavros Baloyannis
The Probable Auto-Antigenic Role of Lipids (Anti-Ganglioside Antibodies) in the Pathogenesis of Alzheimer’s Disease
Abstract: We examined the sera of 103 demented patients of a mean age of 75 years and 60 age-matched healthy individuals, using ELISA, to investigate the levels of IgM antibodies against GM1, GD1b, and GQ1b gangliosides and their possible correlation with clinical parameters (age, severity, and type of dementia). All the individuals that demonstrated positive titers of anti-ganglioside antibodies were demented patients whereas normal controls showed borderline or negative values. Significant correlation was revealed between IgM anti-GM1 and both the age of the patients and the severity of dementia. Most of the patients with increased IgM anti-GD1b titers suffered from AD.
Jorge Ghiso, Silvia Fossati, Agueda Rostagno
Amyloidosis Associated with Cerebral Amyloid Angiopathy: Cell Signaling Pathways Elicited in Cerebral Endothelial Cells
Abstract: Substantial genetic, biochemical, and in vivo data indicate that progressive accumulation of amyloid-β (Aβ) plays a central role in the pathogenesis of Alzheimer’s disease (AD). Historically centered in the importance of parenchymal plaques, the role of cerebral amyloid angiopathy (CAA)—a frequently neglected amyloid deposit present in >80% of AD cases—for the mechanism of disease pathogenesis is now starting to emerge. CAA consistently associates with microvascular modifications, ischemic lesions, micro- and macro-hemorrhages, and dementia, progressively affecting cerebral blood flow, altering blood-brain barrier permeability, interfering with brain clearance mechanisms and triggering a cascade of deleterious pro-inflammatory and metabolic events that compromise the integrity of the neurovascular unit. New evidence highlights the contribution of pre-fibrillar Aβ in the induction of cerebral endothelial cell dysfunction. The recently discovered interaction of oligomeric Aβ species with TRAIL DR4 and DR5 cell surface death receptors mediates the engagement of mitochondrial pathways and sequential activation of multiple caspases, eliciting a cascade of cell death mechanisms while unveiling an opportunity for exploring mechanistic-based therapeutic interventions to preserve the integrity of the neurovascular unit.
Dénes Zádori, Gábor Veres, Levente Szalárdy, Péter Klivényi, József Toldi, László Vécsei
Glutamatergic Dysfunctioning in Alzheimer’s Disease and Related Therapeutic Targets
Abstract: The impairment of glutamatergic neurotransmission plays an important role in the development of Alzheimer’s disease (AD). The pathological process, which involves the production of amyloid-β peptides and hyperphosphorylated tau proteins, spreads over well-delineated neuroanatomical circuits. The gradual deterioration of proper synaptic functioning (via GluN2A-containing N-methyl-D-aspartate receptors, NMDARs) and the development of excitotoxicity (via GluN2B-containing NMDARs) in these structures both accompany the disease pathogenesis. Although one of the most important therapeutic targets would be glutamate excitotoxicity, the application of conventional anti-glutamatergic agents could result in further deterioration of synaptic transmission and intolerable side-effects. With regard to NMDAR antagonists with tolerable side-effects, ion channel blockers with low affinity, glycine site agents, and specific antagonists of polyamine site and GluN2B subunit may come into play. However, in the mirror of experimental data, only the application of ion channel blockers with pronounced voltage dependency, low affinity, and rapid unblocking kinetics (e.g., memantine) and specific antagonists of the GluN2B subunit (e.g., ifenprodil and certain kynurenic acid amides) resulted in desirable symptom amelioration. Therefore we propose that these kinds of chemical agents may have therapeutic potential for present and future drug development.
Merav E. Shaul, Bertan Hallacoglu, Angelo Sassaroli, Barbara Shukitt-Hale, Sergio Fantini, Irwin H. Rosenberg, Aron M. Troen
Cerebral Blood Volume and Vasodilation are Independently Diminished by Aging and Hypertension: A Near InfraRed Spectroscopy Study
Abstract: Background: Senescent changes in brain microvascular circulation may cause or contribute to age-related cognitive decline. Such changes are promoted partly by aging, but also by chronic hypertension, a leading treatable cause of cognitive decline. Objectives: We aimed to non-invasively detect in vivo the senescent changes in brain microvascular circulation associated with age and hypertension, and inquired whether decrements driven by aging would be exacerbated by chronic hypertension. Methods: In this longitudinal study, absolute near infrared spectroscopy (NIRS) was used to quantify in vivo cerebral blood volume (CBV) and assess the hemodynamic response to a hypercapnic respiratory challenge in normotensive Wistar-Kyoto (WKY) and spontaneous-hypertensive (SHR) rats. The impact of age and hypertension were evaluated by repeating these measurements on the same animals at 4- and 16-months of age. Results: CBV decreased markedly with age in both strains, from 4.5±0.2 to 2.6±0.1 ml/100 g tissue, on average. Chronic hypertension, however, did not significantly exacerbate this age-related decrease in CBV (-48.1±3.7% in WKYs versus -53.3±5.4% in SHRs). In contrast, vasoreactivity was already impaired in the young hypertensive rats (ΔVMR 0.017±0.014 in young SHRs versus 0.042±0.005 in young WKYs) and further worsened by middle-age (ΔVMR 0.011±0.017 middle-aged SHRs). Conclusion: Whereas a decrease in brain blood volume correlated with age but not hypertension, vasodilatory capacity was diminished due to hypertension but did not appear affected by age alone. The ability of absolute NIRS to distinguish between such senescent changes in brain (micro)vascular circulation in life may allow early detection and intervention to preserve cerebrovascular health with age.
Ivana Molino, Carlo Cavaliere, Elena Salvatore, Mario Quarantelli, Luisa Colucci, Angiola Maria Fasanaro
Is Anterior Communicating Artery Syndrome Related to Fornix Lesions?
Abstract: Anterior communicating artery (ACoA) syndrome, which may occur after rupture of ACoA aneurysms, consists of anterograde memory problems, executive dysfunctions, confabulations, and personality changes. Recently, the employment of diffusion tensor tractography (DTT) has related ACoA to microstructural lesions in the cingulum and the fornix, but an accurate characterization of these subjects should be provided. We report the clinical and neuropsychological findings of a patient who developed a severe and persistent amnesia together with significant behavioral changes, as well as her imaging results, where the sole evidence of brain damage was that of the fornix demonstrated by DTT. The four-year neuropsychological follow-up of the subject allows exclusion of other causes. This case demonstrates that microstructural lesions of fornix may lead to persistent amnesia, executive impairments, and behavioral changes and contributes to the knowledge of its role in cognition.
Stefanie Schreiber, Benjamin Drukarch, Cornelia Garz, Solveig Niklass, Luiza Stanaszek, Siegfried Kropf, Celine Bueche, Friederike Held, Stefan Vielhaber, Johannes Attems, Klaus G. Reymann, Hans-Jochen Heinze, Roxana O. Carare, Micha M.M. Wilhelmus
Interplay Between Age, Cerebral Small Vessel Disease, Parenchymal Amyloid-β, and Tau Pathology: Longitudinal Studies in Hypertensive Stroke-Prone Rats
Abstract: Background. Accumulation of amyloid-β (Aβ) and hyperphosphorylated tau (ptau) accompany cerebral small vessel disease (CSVD) in the aging brain and in Alzheimer’s disease. CSVD is characterized by a heterogeneous spectrum of histopathological features possibly initiated by an endothelial dysfunction and blood-brain barrier (BBB) breakdown. Objective. We test the hypothesis that characteristic features of CSVD are associated with the accumulation of Aβ and ptau in non-transgenic spontaneously hypertensive stroke-prone rats (SHRSP). Methods. Amyloid-β protein precursor (AβPP) and tau were investigated by western blotting (n=12 SHRSP, age 20 weeks). Lectin staining and plasma protein immunocytochemistry for BBB examination were performed in 38 SHRSP (age 12-44 weeks) and Aβ (n=29) and ptau (n=17) immunocytochemistry in 20-44 week-old SHRSP. We assessed the correlation between extracellular amyloid deposits and features of CSVD (n=135, 12-44 weeks). Results. In 20 week-old SHRSP, cortical AβPP expression was significantly increased compared to Wistar controls but tau levels were unchanged. At ages of 12-44 weeks, SHRSP exhibited an age-dependent increase in extracellular Aβ. Ptau was observed in 26-44 week-old SHRSP. Distinct features of CSVD pathology developed from the age of 12 weeks on. Conclusion. We demonstrate that in a hypertensive rat model that displays features of CSVD from 12 weeks, there is an age-dependent extracellular deposition of Aβ observed from 12 weeks onwards, increased AβPP expression at 20 weeks and ptau accumulation from 26 weeks on. This study suggests that CSVD associated with hypertension results in an age-related failure of Aβ clearance, increase in AβPP expression, and intraneuronal tau hyperphosphorylation.
Irena Rektorova, Lenka Krajcovicova, Radek Marecek, Marie Novakova, Michal Mikl
Default Mode Network Connectivity Patterns associated with Visual Processing at Different Stages of Parkinson’s Disease
Abstract: Background: The default mode network (DMN) decreases its activity when switching from a resting state to a cognitive task condition, while activity of the network engaged in the given task increases. Visual processing is typically disturbed in Parkinson’s disease dementia (PDD). Objective: Using functional MRI, we studied the DMN effective connectivity patterns in PDD as compared with cognitively normal patients with Parkinson’s disease (PD) and healthy controls (HC) when switching from baseline to a visual cognitive task condition. Methods: In all, 14 PDD, 18 PD, and 18 age-matched healthy controls participated in this functional MRI study. We used a psychophysiological interaction analysis with the precuneus (PCu) as a seed. The threshold was set at p(FWE) < 0.05. Results: The healthy controls showed greater PCu connectivity with the bilateral middle temporal/middle occipital gyri at baseline than during the task condition. The correlation direction changed from positive to negative. Both PD and PDD showed disturbed DMN connectivity with the brain regions that are involved in bottom-up visual processing. In PD, we also found impaired integration of the areas engaged in the ventral attentional network, which might reflect specific attentional deficits observed during the early course of PD. In mild PDD, we detected increased engagement of areas involved in the dorsal attentional network, which corresponds to increased top-down control in this patient group as compared to the healthy controls. Conclusion: Our results show impaired dynamic interplay between large scale brain networks in PD that spread far beyond the motor system.
Stephan Seiler, Stefan Ropele, Reinhold Schmidt
Magnetization Transfer Imaging for in vivo Detection of Microstructural Tissue Changes in Aging and Dementia: A Short Literature Review
Abstract: Magnetization-transfer imaging (MTI), a magnetic resonance imaging acquisition protocol, can detect microstructural brain tissue changes by assessing the magnetization exchange between tissue water and protons bound to macromolecules. This short literature review summarizes results of previous MTI studies in normal aging, cerebral small vessel disease, and Alzheimer’s disease (AD). During normal aging, the magnetization transfer ratio (MTR), a measure for the magnitude of magnetization transfer between macromolecular and water protons, declines in normal appearing brain tissue and associations between lower MTR and executive dysfunction have been described. In AD, MTR changes follow a disease-specific temporo-parietal pattern, independent of cortical atrophy. The differential diagnostic contribution beyond atrophy seems to be modest and the independent effect of MTR alterations as predictors of conversion from mild cognitive impairment to AD needs to be explored. MTR correlates well with global cognitive measures like the Mini-Mental State Examination, and MTR decreases rapidly over time in AD. Longitudinal studies are needed to determine the clinical relevance of global and regional MTI measures in normal aging and neurodegenerative disease. Moreover, correlative MTI-histopathologic postmortem studies are warranted to determine the full spectrum of tissue destruction underlying MTR lowering apart from demyelination.
Renée F.A.G. de Bruijn*, Saloua Akoudad*, Lotte G.M. Cremers*, Albert Hofman, Wiro J. Niessen, Aad van der Lugt, Peter J. Koudstaal, Meike W. Vernooij, M. Arfan Ikram *These authors contributed equally to this work.
Determinants, MRI Correlates, and Prognosis of Mild Cognitive Impairment: The Rotterdam Study
Abstract: Mild cognitive impairment (MCI) marks a transitional stage between healthy aging and dementia, but the understanding of MCI in the general population remains limited. We investigated determinants, MRI-correlates, and prognosis of MCI within the population-based Rotterdam Study. Firstly, we studied age, APOE-ɛ4 carriership, waist circumference, hypertension, diabetes mellitus, total and HDL-cholesterol levels, smoking, and stroke as potential determinants of MCI. Determinants were assessed cross-sectionally at baseline (2002-2005) and up to 7 years prior to baseline (1997-2001). Secondly, we compared volumetric, microstructural, and focal MRI-correlates in persons with and without MCI. Thirdly, we followed participants for incident dementia and mortality until 2012. Out of 4,198 participants, 417 had MCI, of whom 163 amnestic and 254 non-amnestic MCI. At baseline, older age, APOE-ɛ4 carriership, lower total cholesterol levels, and stroke were associated with MCI. Additionally, lower HDL-cholesterol levels and smoking were related to MCI when assessed 7 years prior to baseline. Persons with MCI, particularly those with non-amnestic MCI, had larger white matter lesion volumes, worse microstructural integrity of normal-appearing white matter, and a higher prevalence of lacunes, compared to cognitively healthy participants. MCI was associated with an increased risk of dementia (hazard ratio (HR) 3.98, 95% confidence interval (CI) 2.97;5.33), Alzheimer’s disease (HR 4.03, 95% CI 2.92;5.56), and mortality (HR 1.54, 95% CI 1.28;1.85). In conclusion, we found that several vascular risk factors and MRI-correlates of cerebrovascular disease were related to MCI in the general population. Participants with MCI had an increased risk of dementia, including Alzheimer’s disease, and mortality.
Georgios Tsivgoulis, Aristeidis H. Katsanos, Sokratis G. Papageorgiou, Efthimios Dardiotis, Konstantinos Voumvourakis, Sotirios Giannopoulos
The Role of Neurosonology in the Diagnosis of Vascular Dementia
Abstract: Although transcranial sonography is not yet an established diagnostic modality for dementia screening or differential diagnosis of Alzheimer’s disease (AD) from vascular dementia (VaD), intracranial hemodynamic assessment may provide crucial information about the association between cognitive deterioration and vascular risk factors. We conducted a systematic narrative review of available literature through MEDLINE and EMBASE search to identify all available data about the evaluation of VaD patients with transcranial Doppler, and to discuss further the vascular disorders of the cerebral circulation in patients with vascular cognitive impairment. According to the available literature data to date, VaD patients were found to have lower mean flow velocity values in four studies (indicating cerebral hypoperfusion), higher pulsatility indices in three studies (indicating increased downstream vascular resistance), and more severe impairment of cerebrovascular reactivity in five studies (indicating exhausted vasodilatory reserve) compared to AD patients and controls. Microembolic signals were also found to be significantly more common in patients with VaD or AD compared to their age- and gender-matched controls, suggesting that asymptomatic microembolism, apart for being only marker of VaD, could presumably be involved in the genesis of dementia, and in the overlap between VaD and AD. Further studies with larger and carefully selected groups are required to eliminate potential confounders and to set specific cut-off values for the aforementioned hemodynamic parameters in demented patients and dementia subtypes.
Vida Demarin, Sandra Morovic
Ultrasound Subclinical Markers in Assessing Vascular Changes in Cognitive Decline and Dementia
Abstract: Aging is often associated with some cognitive impairment. Greater population life expectancy is one explanation for increased incidence of cognitive impairment cases. Large numbers of people with cognitive impairment and dementia is becoming one of the most important medical and social problems worldwide. Therefore, prevention of cognitive impairment is an imperative. Dementia includes a heterogeneous group of disorders, the most common being Alzheimer’s disease and vascular dementia. Most cardiovascular risk factors, such as hypertension, diabetes mellitus, hypercholesterolemia, atrial fibrillation, and smoking, are not exclusively risk factors for vascular dementia, but also for Alzheimer’s disease. Early changes in the blood vessel wall can be detected by early ultrasound screening methods which allow us to detect changes before the disease becomes clinically evident. Intracranial hemodynamics can be assessed by transcranial Doppler sonography (TCD), functional TCD with various functional tests, and TCD detection of cerebral emboli. Extracranial circulation (carotid and vertebral arteries) can be assessed by means of color Doppler flow imaging. Novel ultrasound technology enables non-invasive, portable, bedside detection of early vascular changes such as arterial stiffness, measurement of the intima-media thickness, pulse-wave velocity, flow-mediated dilation, or endothelial dysfunction in order to obtain information necessary to determine more closely the relation between vascular status and disease development, so that the evolution of cardiovascular disease can be prevented or at least postponed. Early disease detection enables in-time management, and studies have shown that careful control of vascular risk factors can postpone or even reverse disease progression.
Integration of Genomic Information in Development of Pharmacological Vascular Dementia Prevention and Treatment Strategies
Abstract: Treatment of hypertension reduces vascular dementia (VaD) risk but not all anti-hypertensive drugs (AHDs) are equally effective, suggesting drug-gene interactions. To understand this relationship, publicly accessible databases were searched for genes deregulated in VaD and their interactions with AHDs. Genes that were downregulated in association with VaD were MTHFR, SYK, AGT, and RPGRIP1L. Genes that were upregulated in VaD were MMP9 and VEGFA. TNFSF14, AR, and PHLDB2 were also associated with VaD, however, transcription or protein level changes could not be ascertained. Analysis of gene expression data suggests that AHDs differentially regulate VaD-associated genes. Information about AHD up- or downregulation of VaD-associated genes could be used as an empirical basis for the optimal selection of AHDs in clinical trials and, ultimately, for VaD prevention and treatment.
Harry S. Goldsmith
Benefit of Omental Blood Flow in Alzheimer’s Disease: Effect on Deteriorating Neurons
Abstract: It has been commonly believed that a decrease in cerebral blood flow (CBF), which routinely occurs in Alzheimer’s disease (AD), results from the death of critical intracerebral neurons that no longer require the maintenance of an adequate blood supply. This belief is presently being challenged by the idea that it is not neuronal death that causes a decrease in CBF, but actually a decrease in the CBF which leads to the death of neurons seen in AD. In association with dead neurons located within the AD brain are varying numbers of deteriorating neurons. Increasing the CBF to still viable but deteriorating neurons in AD is believed to delay and even improve the clinical manifestations of AD. This increase in CBF has proven effective in treating a group of patients with AD. The increase in CBF was accomplished surgically by placing an intact pedicled omentum directly on the AD brain. While surgery is not a long-term answer in the treatment of AD, the surgical procedure should be evaluated by a carefully controlled study while awaiting the future development of a pharmaceutical method to control the disease.
Francesco Amenta, Anna Carotenuto, Angiola Maria Fasanaro, Raffaele Rea, Enea Traini
The ASCOMALVA (Association between the Cholinesterase Inhibitor Donepezil and the Cholinergic Precursor Choline Alphoscerate in Alzheimer’s Disease) Trial: Interim Results after Two Years of Treatment
Abstract: Cholinesterase inhibitors (ChE-Is) are used for symptomatic treatment of mild-to-moderate Alzheimer's disease (AD), but long-term effects of these compounds are mild and not always obvious. Preclinical studies have shown that combination of ChE-Is and the cholinergic precursor choline alphoscerate increases brain acetylcholine levels more effectively than single compounds alone. ASCOMALVA (Effect of association between a ChE-I and choline alphoscerate on cognitive deficits in AD associated with cerebrovascular injury) is a double-blind trial investigating if the ChE-I donepezil and choline alphoscerate in combination are more effective that donepezil alone. The trial has recruited AD patients suffering from ischemic brain damage documented by neuroimaging and has completed 2 years of observation in 113 patients of the 210 planned. Patients were randomly allotted to an active treatment group (donepezil + choline alphoscerate) or to a reference group (donepezil + placebo). Cognitive functions were assessed by the Mini‐Mental State Evaluation and Alzheimer's Disease Assessment Scale Cognitive subscale. Daily activity was evaluated by the basic and instrumental activities of daily living tests. Behavioral symptoms were assessed by the Neuropsychiatric Inventory. Over the 24-month observation period, patients of the reference group showed a moderate time-dependent worsening in all the parameters investigated. Treatment with donepezil plus choline alphoscerate significantly slowed changes of the different items analyzed. These findings suggest that the combination of choline alphoscerate with a ChE-I may prolong/increase the effectiveness of cholinergic therapies in AD with concomitant ischemic cerebrovascular injury.
Micha M.M. Wilhelmus, Mieke de Jager, Erik N.T.P Bakker, Benjamin Drukarch
Tissue Transglutaminase in Alzheimer’s Disease: Involvement in Pathogenesis and its Potential as a Therapeutic Target
Abstract: Protein misfolding and the formation of stable insoluble protein complexes by self-interacting proteins, in particular amyloid-β and tau protein, play a central role in the pathogenesis of Alzheimer’s disease (AD). Unfortunately, the underlying mechanisms that trigger the misfolding of self-interacting proteins that eventually results in formation of neurotoxic dimers, oligomers, and aggregates remain unclear. Elucidation of the driving forces of protein complex formation in AD is of crucial importance for the development of disease-modifying therapies. Tissue transglutaminase (tTG) is a calcium-dependent enzyme that induces the formation of covalent ε-(γ-glutamyl)lysine isopeptide bonds, which results in both intra- and intermolecular protein cross-links. These tTG-catalyzed intermolecular cross-links induce stable, rigid, and insoluble protein complexes, whereas intramolecular cross-links change the conformation of proteins. Inhibition of tTG-catalyzed cross-linking counteracts the formation of protein aggregates, as observed in disease-models of other protein misfolding diseases, in particular Parkinson’s and Huntington’s diseases. Although data of tTG activity in AD models is limited, there is compelling evidence from both in vitro and postmortem human brain tissue of AD patients that point toward a crucial role for tTG in the pathogenesis of AD. Here, we review these data on the role of tTG in the initiation and development of protein aggregates in AD, and discuss the possibility to use inhibitors of the cross-linking activity of tTG as a new therapeutic approach for AD.
Celine Zoe Bueche, Cornelia Garz, Luiza Stanaszek, Solveig Niklass, Siegfried Kropf, Daniel Bittner, Wolfgang Härtig, Klaus G. Reymann, Hans-Jochen Heinze, Roxana O. Carare, Stefanie Schreiber
Impact of N-Acetylcysteine on Cerebral Amyloid-β Plaques and Kidney Damage in Spontaneously Hypertensive Stroke-Prone Rats
Abstract: Background: Cerebral small vessel disease (CSVD) in spontaneously hypertensive stroke prone rats (SHRSP) is accompanied by parenchymal amyloid-β (Aβ) deposition in the brain and by hypertensive nephropathy with tubulointerstitial damage. N-acetylcysteine (NAC) promotes blood-brain barrier (BBB) breakdown in SHRSP and may thus accelerate the failure of vascular and perivascular clearance of Aβ. Objective: In this study, we test the hypothesis that treatment with NAC increases the cerebral Aβ load and improves renal damage in the SHRSP model. Methods: A total of 46 SHRSP (ages 18-44 weeks) were treated daily with NAC (12 mg/kg body weight) and 74 no-treated age-matched SHRSP served as controls. The prevalence of parenchymal Aβ load, IgG positive small vessels, and small perivascular bleeds was assessed in different brain regions. Tubulointerstitial kidney damage was assessed through a) the presence of erythrocytes in peritubular capillaries and b) tubular protein cylinders. Results: SHRSP treated with NAC had an age-dependent increase of BBB breakdown (assessed by the presence of IgG positive small vessels) and small perivascular bleeds, mainly in the cortex. NAC significantly increased the Aβ plaque load in the cortex while the number of parenchymal amyloid deposits in the remaining brain areas including basal ganglia, hippocampus, thalamus, and corpus callosum were unchanged. There were no significant treatment effects on tubulointerstitial kidney damage. Conclusion: The impact of NAC on cerebral cortical plaque load increase may result from the vascular pathology of SHRSP that accompanies BBB breakdown, leading to the failure of amyloid clearance mechanisms. It remains to be seen whether in humans chronic NAC intake may increase amyloid load in the aging human brain and dementia.
Sotirios Giannopoulos*, Aristeidis H Katsanos*, Maria Kosmidou, Georgios Tsivgoulis *These authors contributed equally to this work.
Statins and Vascular Dementia: A Review
Abstract: The impact of statin therapy on dementia has been a hot topic of debate over the last decade and still remains highly controversial. Among all causes of dementia, vascular dementia (VaD) is the one type that is more likely to benefit from statins. To date no randomized clinical trials have been published and no systematic review has investigated a possible preventive effect of statins on the VaD subtype. In the present literature review, we tried to identify all available data on the effect of statins specifically in patients with VaD, and to further discuss this possible association. Our literature search highlighted two cross-sectional studies, two prospective cohort studies, and one retrospective cohort study. Two of the studies found a significant positive effect of statin treatment on VaD, depicted by the lower incidence of VaD in statin users, while the others reported non-significant associations. The relatively small numbers of VaD patients and statin users, as well as the presence of confounders and biases, make the interpretation of results extremely difficult. Statins may exert a benefit in the prevention of all-type dementia and VaD, through several mechanisms except for hyperlipidemia reduction. A well-designed randomized clinical trial is the ideal study design to address the effect of statin therapy in VaD and to draw final conclusions.
Fabricio Ferreira de Oliveira, Paulo Henrique Ferreira Bertolucci, Elizabeth Suchi Chen, Marilia Cardoso Smith
Brain-Penetrating Angiotensin-Converting Enzyme Inhibitors and Cognitive Change in Patients with Dementia due to Alzheimer’s Disease
Abstract: Controversy over benefits of angiotensin-converting enzyme inhibitors (ACEIs) for treatment of dementia due to Alzheimer’s disease (AD) led to this alternative investigational approach by the employment of pharmacogenetic methods, correlating the cognitive change of patients with late-onset AD with the presence of common ACE gene promoter polymorphisms, and stratifying the sample in groups of patients who responded or not to the brain-penetrating ACEIs Captopril or Perindopril. A trend was found for treatment with brain-penetrating ACEIs to slow cognitive decline in AD patients with the haplotype rs1800764 (CC): rs4291 (TT) (ρ=0.024), and also non-significantly for independent carriers of rs1800764 or rs4291.