Link to full text for this issue
Pages 417-425
Review
Beatrice Arosio, Martina Casati, Cristina Gussago, Evelyn Ferri, Carlo Abbate, Valeria Scortichini, Elena Colombo, Paolo Dionigi Rossi, Daniela Mari (Handling Associate Editor: Patrizia Mecocci)
Adenosine Type A2A Receptor in Peripheral Cell from Patients with Alzheimer’s Disease, Vascular Dementia, and Idiopathic Normal Pressure Hydrocephalus: A New/Old Potential Target
Abstract: As the European population gets older, the incidence of neurological disorders increases with significant impact on social costs. Despite differences in disease etiology, several brain disorders in the elderly (e.g., Alzheimer’s disease, vascular dementia, normal pressure hydrocephalus) share dementia as a common clinical feature. The current treatment for the majority of these diseases is merely symptomatic and does not modify the course of the illness. Symptoms of normal pressure hydrocephalus are the only ones that can be modified if they are recognized in time and treated appropriately. Therefore, an important clinical strategy may be disclosed by pathogenic pathways that can be modified and to find drugs that can slow down or even arrest disease progression. Possibly a way to answer this question could be by re-examining all the molecules which have so far succeeded in improving many aspects of cognitive deterioration in some neurodegenerative conditions, that were not considered because of controversial opinions. The main purpose of this summary is to further substantiate the hypothesis that the pathway of adenosine type A2A receptor could be used as a potential target to develop new/old therapeutic strategies.
Pages 427-443
Review
Murali Vijayan, P. Hemachandra Reddy
Stroke, Vascular Dementia, and Alzheimer’s Disease: Molecular Links
Abstract: Stroke is a brain disease that occurs when blood flow stops, resulting in reduced oxygen supply to neurons. Stroke occurs at any time and at any age, but increases after the age of 55. It is the second leading cause of death and the third leading cause of disability-adjusted, life-years. The pathophysiology of ischemic stroke is complex and recent molecular, cellular, and animal models and postmortem brain studies have revealed that multiple cellular changes have been implicated, including oxidative stress/mitochondrial dysfunction, inflammatory responses, micro RNA alterations, and marked changes in brain proteins. These cellular changes provide new information for developing therapeutic strategies for ischemic stroke treatment. Research also revealed that stroke increases with a number of modifiable factors and most strokes can be prevented and/or controlled through pharmacological or surgical interventions and lifestyle changes. Ischemic stroke is the major risk factor for vascular dementia and Alzheimer’s disease. This review summarizes the latest research findings on stroke, including causal factors and molecular links between stroke and vascular disease/Alzheimer’s disease.
Pages 445-456
Review
Eric L. Goldwaser, Nimish K. Acharya, Abhirup Sarkar, George Godsey, Robert G. Nagele (Handling Associate Editor: Thomas Shea)
Breakdown of the Cerebrovasculature and Blood-Brain Barrier: A Mechanistic Link Between Diabetes Mellitus and Alzheimer’s Disease
Abstract: Alzheimer’s disease (AD) and diabetes mellitus (DM) are among the most pervasive and devastating disorders that afflict people throughout the world. Although typically associated with older demographics, recent epidemiologic studies have reported parallel trends in decreasing age of onset and increasing incidence of these conditions. Promising research continues to implicate the cerebrovasculature and blood-brain barrier (BBB) as playing key roles in AD pathoetiology. Similarly, complications accompanying DM, such as diabetic nephropathy/retinopathy, cardiovascular disease, and stroke, have been rooted in vascular compromise. Not surprisingly, DM is now considered a major risk factor for AD. The purpose of this review is to highlight investigations into the role of the cerebrovasculature in the development and progression of AD. We give particular attention to studies on humans and a variety of animal model systems that have demonstrated a link between BBB dysfunction and pathological changes in the brain consistent with aging and AD. Together, these studies suggest that the vascular complications associated with chronic, poorly managed DM can lead to subclinical BBB breakdown that precedes and drives the pathological changes progressing to symptomatic AD, providing a common mechanistic thread connecting these two disorders. Furthermore, this emphasizes the need to focus on the vasculature as a potential therapeutic target with the intent of limiting BBB breakdown involved in disease initiation and progression. In conclusion, AD may be more than just an associated comorbidity of DM, and instead another manifestation of the underlying vascular pathology that is common to both.
Pages 457-470
Hypothesis
Conrad N. Trumbore
Shear-Induced Amyloid Formation in the Brain: I. Potential Vascular and Parenchymal Processes
Abstract: Shear distortion of amyloid-beta (Aβ) solutions accelerates amyloid cascade reactions that may yield different toxic oligomers than those formed in quiescent solutions. Recent experiments indicate that cerebrospinal fluid and interstitial fluid (ISF) containing Aβ flow through narrow brain perivascular pathways and brain parenchyma. This paper suggests that such flow causes shear distortion of Aβ molecules involving conformation changes that may be one of the initiating events in the etiology of Alzheimer’s disease. Aβ shearing can occur in or around brain arteries and arterioles and is suggested as the origin of cerebral amyloid angiopathy deposits in cerebrovascular walls. Comparatively low flow rates of ISF within the narrow extracellular spaces (ECS) of the brain parenchyma are suggested as a possible initiating factor in both the formation of neurotoxic Aβ42 oligomers and amyloid fibrils. Aβ42 in slow-flowing ISF can gain significant shear energy at or near the walls of tortuous brain ECS flow paths, promoting the formation of a shear-distorted, excited state hydrophobic Aβ42* conformation. This Aβ42* molecule could possibly be involved in one of two paths, one involving rapid adsorption to a brain membrane surface, ultimately forming neurotoxic oligomers on membranes, and the other ultimately forming plaque within the ECS flow pathways. Rising Aβ concentrations combined with shear at or near critical brain membranes are proposed as contributing factors to Alzheimer’s disease neurotoxicity. These hypotheses may be applicable in other neurodegenerative diseases, including tauopathies and alpha-synucleinopathies, in which shear-distorted proteins also may form in the brain ECS.
Pages 471-475
Short Communication
Irene López-González*, Andre Palmeira*, Ester Aso, Margarita Carmona, Liana Fernandez, Isidro Ferrer *These authors contributed equally to this work.
FOXP2 Expression in Frontotemporal Lobar Degeneration-Tau
Abstract: FOXP2 is altered in a variety of language disorders. We found reduced mRNA and protein expression of FOXP2 in frontal cortex area 8 in Pick’s disease, and frontotemporal lobar degeneration-tau linked to P301L mutation presenting with language impairment in comparison with age-matched controls and cases with parkinsonian variant progressive supranuclear palsy. Foxp2 mRNA and protein are also reduced with disease progression in the somatosensory cortex in transgenic mice bearing the P301S mutation in MAPT when compared with wild-type littermates. Our findings support the presence of FOXP2 expression abnormalities in sporadic and familial frontotemporal degeneration tauopathies.
Pages 477-496
Merina Varghese, Ismael Santa-Maria, Lap Ho, Libby Ward, Shrishailam Yemul, Lauren Dubner, Hanna Księżak-Reding, Giulio Maria Pasinetti
Extracellular Tau Paired Helical Filaments Differentially Affect Tau Pathogenic Mechanisms in Mitotic and Post-Mitotic Cells: Implications in Mechanisms of Tau Propagation in the Brain
Abstract: The release of paired helical filaments (PHFs) from neurons into the extracellular space may contribute to the propagation of tau pathology across brain regions in Alzheimer’s disease (AD) and other tauopathies. The majority of available mechanistic studies exploring the pathologic role of extracellular PHFs are conducted in proliferating cell lines. Here, we compare how extracellular PHFs induce tauopathy in mitotic cells and in post-mitotic brain neurons. In a mitotic cell line (HEK 293), extracellular exposure to AD PHFs leads to an intracellular “aggresomal” type deposition of tau, coincidental with redistribution of dynein, a retrograde motor protein. We also observed that PHFs impaired proteasome degradation, but not autophagy. Exposure of cells to proteasome inhibitors was sufficient to induce intracellular tau aggregate formation and reorganization of dynein and the intermediate filament protein, vimentin. Thus, in mitotic cells, extracellular PHFs promote cellular tau aggregation, in part, by interfering with cellular proteasome degradation processes. In contrast with our observations that with proliferating cells, exposure of post-mitotic primary neuronal cultures to AD PHFs did not promote “aggresomal” tau deposition, but instead resulted in a widespread accumulation of phosphorylated tau-immunoreactive swellings in neuritic processes, characterized by disturbed cytoskeletal organization of dynein and vimentin. Collectively, our observations suggest that extracellular PHFs may contribute to the propagation of tau pathology by independent mechanisms in post-mitotic and mitotic brain cells. These outcomes suggest that in addition to post-mitotic brain neurons, mitotic brain cells should also be considered as targets for therapeutic interventions to attenuate propagation of tauopathy.
Pages 497-503
Mary Cushman, Peter W. Callas, Leslie A. McClure, Frederick W. Unverzagt, Virginia J. Howard, Sarah R. Gillett, Evan L. Thacker, Virginia G. Wadley
N-Terminal Pro-B-Type Natriuretic Peptide and Risk of Future Cognitive Impairment in the REGARDS Cohort
Abstract: Background: Improved understanding of the etiology of cognitive impairment is needed to develop effective preventive interventions. Higher amino-terminal pro-B-type natriuretic peptide (NT-proBNP) is a biomarker of cardiac dysfunction associated with risk cardiovascular diseases and stroke in apparently healthy people. Objective: To study the association of NT-proBNP with risk of incident cognitive impairment. Methods: The Reasons for Geographic and Racial Differences in Stroke is a national cohort study of 30,239 black and white Americans age 45 and older at baseline, enrolled in 2003-7. Among participants without prebaseline stroke or cognitive impairment, baseline NT-proBNP was measured in 470 cases of incident cognitive impairment and 557 controls. Cases were participants scoring below the 6th percentile of demographically-adjusted means on at least 2 of 3 serially administered tests (word list learning, word list recall and semantic fluency) over 3.5 years follow-up. Results: Adjusting for age, gender, race, region of residence, education, and income, there was an increased odds ratio of incident cognitive impairment with increasing NT-proBNP; participants in the 4th versus 1st quartile (>127 versus ≤33 pg/ml) had a 1.69-fold increased odds (95% CI 1.11-2.58). Adjustment for cardiovascular risk factors and presence of an apolipoprotein E4 allele had no substantial impact on the odds ratio. Results did not differ by age, race, gender, or presence of an apolipoprotein E4 allele. Conclusion: Higher NT-pro-BNP was associated with incident cognitive impairment in this prospective study, independent of atherogenic and Alzheimer’s disease risk factors. Future work should clarify pathophysiologic connections of NT-proBNP and cognitive dysfunction.
Pages 505-514
Lea Stevnsborg, Christina Jensen-Dahm, Thomas R. Nielsen, Christiane Gasse, Gunhild Waldemar (Handling Associate Editor: Heidi Taipale)
Inequalities in Access to Treatment and Care for Patients with Dementia and Immigrant Background: A Danish Nationwide Study
Abstract: Background: Previous studies demonstrated lower quality diagnostic assessment of dementia in immigrant populations, but knowledge about the quality of treatment and care for dementia is still lacking. Objective: To conduct a nationwide registry-based study to determine whether inequality exists regarding access to anti-dementia treatment and care between immigrant and Danish-born patients with dementia. Methods: A cross-sectional register-based study was conducted in the entire elderly (60≥ years) population with dementia in Denmark in 2012 (n=34,877). The use of anti-dementia drugs and residency in a nursing home were compared among Danish-born and Western and non-Western immigrants with dementia. Logistic regression analysis was done with adjustment for age, sex, comorbidity, marital status, basis of inclusion, and time since dementia diagnosis. Results: Immigrant background was associated with a significantly lower likelihood of receiving anti-dementia drug therapy (odds ratio (OR) [95% confidence interval (CI)]): non-Western = 0.70 [0.56-0.87]; Western = 0.74 [0.63-0.87]). No significant differences were found in type or amount of anti-dementia medication dispensed between the population groups (proxy measure for adherence). Non-Western immigrants were significantly less likely to live in a nursing home (0.52 [0.41-0.65]). Conclusion: This nationwide registry-based study indicated a worrisome difference in access to anti-dementia treatment and care for dementia patients with an immigrant background, but similar levels of adherence compared with the Danish-born population. Further research is necessary to pinpoint barriers to access to suitable healthcare among elderly immigrants with dementia but also to identify and develop culturally sensitive methods for their treatment and care.
Pages 515-523
Mohamad El Haj, Pascal Antoine
Death Preparation and Boredom Reduction as Functions of Reminiscence in Alzheimer’s Disease
Abstract: Reminiscence, or the process of thinking or telling about past experience, is thought to serve social, instrumental, and integrative functions. Our paper investigated these functions in Alzheimer’s disease (AD). Twenty-six participants with a clinical diagnosis of probable mild AD and 28 control older adults filled in a French adaptation of the Reminiscence Functions Scale. Eight specific functions were assessed: death preparation, identity, problem-solving, teaching/informing, conversation, boredom reduction, bitterness revival, and intimacy maintenance. Both older adults and AD participants reported reminiscence about their past to prepare themselves for the idea of their own mortality. All participants also reported reminiscence “to reduce boredom” and “for something to do”. However, reminiscence for death preparation and boredom reduction was reported more by AD participants than by older adults. In all participants, the death preparation function of reminiscence was significantly correlated with depression. Individuals with AD seem to reminiscence to cope with thoughts about their own mortality. This helps them to see that they have lived a full life and can therefore accept death more calmly. Individuals with AD also seem to cope with boredom by using reminiscence, probably as a tool to fill time or simply to create ease of conversation.
Pages 525-533
Binukumar BK, Steven L. Pelech, Catherine Sutter, Varsha Shukla, Niranjana D. Amin, Philip Grant, Manju Bhaskar, Suzanne Skuntz, Joseph Steiner, Harish C. Pant
Profiling of p5, a 24 Amino Acid Inhibitory Peptide Derived from the CDK5 Activator, p35 CDKR1 Against 70 Protein Kinases
Abstract: Cyclin-dependent kinase 5 (CDK5) is multifunctional protein-serine/threonine kinase that regulates a large number of neuronal processes essential for nervous system development and function with its activator p35 CDK5R1. Upon neuronal insults, p35 is proteolyzed and cleaved to p25 producing deregulation and hyperactivation of CDK5 (CDK5/p25), implicated in the hyperphosphorylation of tau and many neurodegenerative diseases. A truncated, 24 amino acid peptide, p5, derived from p25 and p35 inhibits the deregulated CDK5 phosphotransferase activity and ameliorates Alzheimer’s disease (AD) phenotypes in AD model mice. In the present study, we have screened a diverse panel of 70 human protein kinases for their sensitivities to p5, and a subset of these to p35. At least 16 of the tested protein kinases exhibited IC50 values that were 250 µM or less, with CAMK4, ZAP70, SGK1, and PIM1 showing greater sensitivity to inhibition by p5 than CDK5/p35 and CDK5/p25. By contrast, the p5 peptide modestly activated LKB1 and GSK3β. The phosphotransferase activity of CAMK4 in the absence of calcium and calmodulin was also markedly inhibited by p35. The Cyclin Y-dependent kinases PFTK1 (CDK14) and PCTK1 (CDK16) were activated by p35 at least 10-fold in the absence of Cyclin Y and by approximately 50% in its presence. These findings provide additional insights into the mechanisms of action for p5 and p35 in the regulation of protein phosphorylation in the nervous system.
Pages 535-547
Nicoletta Marchesi, Marialaura Amadio, Claudia Colombrita, Stefano Govoni, Antonia Ratti, Alessia Pascale
PKC Activation Counteracts ADAM10 Deficit in HuD-Silenced Neuroblastoma Cells
Abstract: Neuronal ELAV/Hu (nELAV) are RNA-binding proteins that mainly regulate gene expression by increasing the stability and/or translation rate of target mRNAs bearing ARE (adenine and uracil-rich elements) sequences. Among nELAV target transcripts there is ADAM10, an α-secretase involved in the non-amyloidogenic processing of the amyloid-β protein precursor (AβPP) which leads to the production of the neuroprotective sAβPPα peptide. The aim of this study was to evaluate if nELAV depletion affects ADAM10 expression in human SH-SY5Y neuroblastoma cells. We also studied the effects of Bryostatin-1, a molecule able to activate nELAV protein cascade. The specific HuD/nELAV gene silencing decreased both nELAV and ADAM10 protein contents; similar results were obtained by Aβ40 treatment in wild-type SH-SY5Y cells. In HuD-silenced cells, the exposure to Bryostatin-1 counteracted both nELAV and ADAM10 proteins downregulation, by restoring nELAV/ADAM10 basal levels. We also found that sAβPPα release, which seemed not to be compromised by Aβ40 challenge or HuD-silencing, was favored by Bryostatin-1. Overall, these findings strongly suggest that a deficiency in nELAV content negatively affects ADAM10 expression and may play a role in neurodegenerative diseases, which may benefit by molecules activating ELAV cascade.
Pages 549-558
Akira Midorikawa, Cristian E. Leyton, David Foxe, Ramon Landin-Romero, John R. Hodges, Olivier Piguet
All Is Not Lost: Positive Behaviors in Alzheimer’s Disease and Behavioral-Variant Frontotemporal Dementia with Disease Severity
Abstract: Background: Anecdotal evidence indicates that some patients with dementia exhibit novel or increased positive behaviors, such as painting or singing, after the disease onset. Due to the lack of objective measures, however, the frequency and nature of these changes has not been formally investigated. Objective: This study aimed to systematically identify changes in these behaviors in the two most common younger-onset dementia syndromes: Alzheimer’s disease (AD) and behavioral-variant frontotemporal dementia (bvFTD). Methods: Sixty-three caregivers of patients with dementia (32 caregivers of AD patients and 31 caregivers of bvFTD patients) participated in the study. Caregivers rated the presence and frequency of positive and negative behavior changes after the onset of dementia using the Hypersensory and Social/Emotional Scale (HSS) questionnaire, focusing on three domains: sensory processing, cognitive skills, and social/emotional processing. Six composites scores were obtained reflecting these three domains (two composite scores for each domain). Differences across scores and ratios of increased and decreased behaviors were analyzed between AD and bvFTD, at different disease severity levels. Results: After disease onset, significant changes in the sensory processing domain were observed across disease severity levels, particularly in AD. Composite scores of the other domains did not change significantly. Importantly, however, some novel or increased positive behaviors were present in between 10% (Music activities) and 70% (Hypersensitivity) of AD and bvFTD patients, regardless of disease severity. Conclusions: We provide the first systematic investigation of positive behaviors in AD and bvFTD. The newly developed HSS questionnaire is a valid measure to characterize changes and progression of positive behaviors in patients with dementia.
Pages 559-568
Eun Hyun Seo, Sang Hoon Kim, Sang Hag Park, Seong-Ho Kang, IL Han Choo for the Alzheimer’s Disease Neuroimaging Initiative (Handling Associate Editor: Jun-Young Lee)
Topographical APOE ε4 Genotype Influence on Cerebral Metabolism in the Continuum of Alzheimer’s Disease: Amyloid Burden Adjusted Analysis
Abstract: Background: APOE ε4 contributes to Alzheimer’s disease (AD) pathogenesis by amyloid-beta (Aβ)-dependent and Aβ-independent processes. Objective: We investigated the APOE ε4 influence on regional cerebral glucose metabolism (rCMglc) in the continuum of AD after Aβ adjustment. Methods: We included 318 cognitively normal (CN) elderly, 498 mild cognitive impairment (MCI), and 178 AD from the Alzheimer’s Disease Neuroimaging Initiative database. They had [18F] florbetapir positron emission tomography (PET) and [18F] fluorodeoxyglucose (FDG)-PET conducted within 3 months of a clinical and cognitive assessment visit and APOE genotype. At first, the rCMglc differences between APOE ε4 carriers (ε4+) and non-carriers (ε4-) were estimated on a voxel-based analysis using a ‘two-sample t-test’ design. In the second analysis, Aβ was added as covariate. Results: In CN, ε4+ showed reduced rCMglc compared to ε4- in the bilateral frontal, temporal, and the left parietal regions. In MCI, ε4+ showed reduced rCMglc compared to ε4- in the bilateral posterior parietal, temporal, and left frontal regions. In AD, ε4+ showed reduced rCMglc in the left hippocampus, right insular, and right temporal gyrus. However, after Aβ adjustment, the significant differences in the temporal regions were absent in CN and MCI, and none of the areas detected as significant in the first analysis were statistically significant in AD. Conclusions: Our study demonstrated that Aβ-independent APOE ε4 influence on rCMglc is limited to the parietal and frontal, but not temporal lobes. These results suggest that APOE ε4 may predispose for regional vulnerability according to Aβ-independent and Aβ-dependent processes.
Pages 569-584
YuHong Fu, Jen-Hsiang T. Hsiao, George Paxinos, Glenda M. Halliday, Woojin Scott Kim
ABCA7 Mediates Phagocytic Clearance of Amyloid-β in the Brain
Abstract: Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by dementia and abnormal deposits of aggregated amyloid-β in the brain. Recent genome-wide association studies have revealed that ABCA7 is strongly associated with AD. In vitro evidence suggests that the role of ABCA7 is related to phagocytic activity. Deletion of ABCA7 in a mouse model of AD exacerbates cerebral amyloid-β plaque load. However, the biological role of ABCA7 in AD brain pathogenesis is unknown. We show that ABCA7 is highly expressed in microglia and when monocytes are differentiated into macrophages. We hypothesized that ABCA7 plays a protective role in the brain that is related to phagocytic clearance of amyloid-β. We isolated microglia and macrophages from Abca7-/- and wild type mice and tested them for their capacity to phagocytose amyloid-β oligomers. We found that the phagocytic clearance of amyloid-β was substantially reduced in both microglia and macrophages from Abca7-/- mice compared to wild type mice. Consistent with these results, in vivo phagocytic clearance of amyloid-β oligomers in the hippocampus was reduced in Abca7-/- mice. Furthermore, ABCA7 transcription was upregulated in AD brains and in amyloidogenic mouse brains specifically in the hippocampus as a response to the amyloid-β pathogenic state. Together these results indicate that ABCA7 mediates phagocytic clearance of amyloid-β in the brain, and reveal a mechanism by which loss of function of ABCA7 increases the susceptibility to AD.
Pages 585-595
Siwei Liu*, Yi-Ting Ong*, Saima Hilal, Yng Miin Loke, Tien Y. Wong, Christopher Li-Hsian Chen, Carol Y. Cheung+, Juan Zhou+ *Joint first authors; +Joint senior authors
The Association Between Retinal Neuronal Layer and Brain Structure is Disrupted in Patients with Cognitive Impairment and Alzheimer’s Disease
Abstract: Both healthy and pathological aging due to Alzheimer’s disease (AD) are associated with decreased brain grey matter volume (GMV) and disrupted white matter (WM) microstructure. Thinner macular ganglion cell-inner plexiform layer (GC-IPL) measured by spectral-domain optical coherence tomography has been reported in patients with AD and mild cognitive impairment. Emerging evidence suggested a link between thinner GC-IPL and lower GMV in subjects with no dementia using region-of-interest-based approach. However, it remains unknown whether GC-IPL thickness is associated with brain WM microstructure and how such association differed between normal and cognitively impaired subjects. Here, for subjects with no cognitive impairment (NCI), thinner GC-IPL was associated with lower WM microstructure integrity in the superior longitudinal fasciculus, inferior fronto-occipital fasciculus, corticospinal tracts, anterior thalamic radiation, and cingulum regions, while it was weakly associated with lower GMV in visual cortex and cerebellum. Nevertheless, these retina-brain associations were disrupted in the presence of cognitive impairment. Correlations between GMV and GC-IPL were lost in patients with cognitive impairment but no dementia (CIND) and AD patients. GC-IPL was related to WM microstructural disruption in similar regions with decreased significance. In contrast, lower WM microstructure integrity in the fornix showed a trend of correlation with thinner GC-IPL in both CIND and AD but not NCI. Collectively, our findings suggest the possible physiological retina-brain relationship in healthy aging, which might be disrupted by disease-induced changes in patients with cognitive impairment. Longitudinal study with larger patient sample should follow to confirm the disease mechanism behind these retina-brain relationship changes.
Pages 597-613
Lilian Calderón-Garcidueñas, José Avila-Ramírez, Ana Calderón-Garcidueñas, Tonatiuh González-Heredia, Hilda Acuña-Ayala, Chih-kai Chao, Charles Thompson, Rubén Ruiz- Ramos, Victor Cortés-González, Luz Martínez-Martínez, Mario Alberto García-Pérez, Jacques Reis, Partha S. Mukherjee, Ricardo Torres-Jardón, Ingolf Lachmann (Handling Associate Editor: Piotr Lewczuk)
Cerebrospinal Fluid Biomarkers in Highly Exposed PM2.5 Urbanites: The Risk of Alzheimer’s and Parkinson’s Diseases in Young Mexico City Residents
Abstract: Exposure to fine particulate matter (PM2.5) and ozone (O3) above US EPA standards is associated with Alzheimer’s disease (AD) risk, while Mn toxicity induces parkinsonism. Mexico City Metropolitan Area (MCMA) children have pre- and postnatal sustained and high exposures to PM2.5, O3, polycyclic aromatic hydrocarbons, and metals. Young MCMA residents exhibit frontal tau hyperphosphorylation and amyloid-β (Aβ)1-42 diffuse plaques, and aggregated and hyperphosphorylated α-synuclein in olfactory nerves and key brainstem nuclei. We measured total prion protein (TPrP), total tau (T-tau), tau phosphorylated at threonine 181 (P-Tau), Aβ1-42, α-synuclein (t-α-syn and d-α-synuclein), BDNF, insulin, leptin, and/or inflammatory mediators, in 129 normal CSF samples from MCMA and clean air controls. Aβ1-42 and BDNF concentrations were significantly lower in MCMA children versus controls (p=0.005 and 0.02, respectively). TPrP increased with cumulative PM2.5 up to 5 μg/m3 and then decreased, regardless of cumulative value or age (R2= 0.56). TPrP strongly correlated with T-Tau and P-Tau, while d-α-synuclein showed a significant correlation with TNFα, IL10, and IL6 in MCMA children. Total synuclein showed an increment in childhood years related to cumulated PM2.5 , followed by a decrease after age 12 years (R2 =0.47), while d-α-synuclein exhibited a tendency to increase with cumulated PM2.5 (R2 =0.30). CSF Aβ1-42, BDNF, α-synuclein, and TPrP changes are evolving in young MCMA urbanites historically showing underperformance in cognitive processes, odor identification deficits, downregulation of frontal cellular PrP, and neuropathological AD and PD hallmarks. Neuroprotection of young MCMA residents ought to be a public health priority.
Pages 615-633
Eric E. Brown, Yusuke Iwata, Jun Ku Chung, Philip Gerretsen, Ariel Graff-Guerrero (Handling Associate Editor: Yumiko Motoi)
Tau in Late-Life Depression: A Systematic Review and Meta-Analysis
Abstract: A lifetime history of major depressive disorder (MDD) increases the risk of developing Alzheimer’s disease, of which neurofibrillary tangles due to abnormal tau proteins are a hallmark. We systematically reviewed the literature on tau in MDD and identified 49 relevant articles spanning a number of modalities, including cerebrospinal fluid (CSF) analysis, positron emission tomography, and clinicopathological correlation. We compared CSF total and phosphorylated tau proteins in MDD and controls using a meta-analytic approach. We found no difference in total or phosphorylated tau in MDD. We also found no difference in a comparison of a subgroup excluding studies with significant age differences. Positron emission tomography studies lacked specificity. Clinicopathological studies failed to associate neurofibrillary tangles with MDD. The available data on tau in MDD is limited. The involvement of tau in a subset of MDD cannot be ruled out and requires prospective exploration.
Pages 635-643
Shinji Matsunaga, Taro Kishi, Nakao Iwata
Yokukansan in the Treatment of Behavioral and Psychological Symptoms of Dementia: An Updated Meta-Analysis of Randomized Controlled Trials
Abstract: Background: Previous clinical studies found that yokukansan has a therapeutic effect on behavioral and psychological symptoms of dementia (BPSD) in dementia patients. Objective: To perform an updated meta-analysis of randomized controlled trials (RCTs) testing yokukansan for patients with BPSD. Methods: Primary efficacy and safety endpoints were BPSD total scores and all-cause discontinuation, respectively. Secondary outcomes were BPSD subscales, cognitive function scores [Mini-mental state examination (MMSE)], activities of daily living (ADL) scores, discontinuation due to adverse events (AEs), and incidences of AEs. Results: Five RCTs with 381 patients with BPSD were included. Compared with controls [placebo + usual care (UC)], yokukansan significantly decreased BPSD total scores [standardized mean difference (SMD) = −0.32, 95% confidence interval (CI) = −0.53 to −0.11, p = 0.003, I2 = 0%, N = 5 studies, n = 361]. Yokukansan was more efficacious in reducing BPSD subscale scores (delusions: SMD = −0.51, 95% CI = −0.98 to −0.04, hallucinations: SMD = −0.54, 95%CI = −0.96 to −0.12, agitation/aggression: SMD = −0.37, 95% CI = −0.60 to −0.15) than placebo + UC. However, yokukansan was not superior to placebo + UC for BPSD total as well as any subscales scores only in Alzheimer’s disease patients. Compared with UC, yokukansan treatment improved ADL scores (SMD = −0.32, 95% CI = −0.62 to −0.01). MMSE scores did not differ between the yokukansan and placebo + UC treatment groups. No significant differences were found in all-cause discontinuation, discontinuation due to AEs, and incidences of AEs between yokukansan and placebo + UC treatments. Conclusions: Our results suggest that yokukansan is beneficial for the treatment of patients with BPSD and is well-tolerated; it was not beneficial for BPSD total and any subscale scores only in Alzheimer’s disease patients.
Pages 645-656
Lara Ordoñez-Gutierrez, Ivan Fernandez-Perez, Jose Luis Herrera, Marta Anton, Irene Benito-Cuesta, Francisco Wandosell
AβPP/PS1 Transgenic Mice Show Sex Differences in the Cerebellum Associated with Aging
Abstract: Cerebellar pathology has been related to presenilin 1 mutations in certain pedigrees of familial Alzheimer's disease. However, cerebellum tissue has not been intensively analyzed in transgenic models of mutant presenilins. Furthermore, the effect of the sex of the mice was not systematically analyzed, despite the fact that important gender differences in the evolution of the disease in the human population have been described. We analyzed whether the progression of amyloidosis in a double transgenic mouse, AβPP/PS1, is susceptible to aging and differentially affects males and females. The accumulation of amyloid in the cerebellum differentially affects males and females of the AβPP/PS1 transgenic line, which was found to be ten-fold higher in 15-month-old females. Amyloid-β accumulation was more evident in the molecular layer of the cerebellum, but glia reaction was only observed in the granular layer of the older mice. The sex divergence was also observed in other neuronal, survival, and autophagic markers. The cerebellum plays an important role in the evolution of the pathology in this transgenic mouse model. Sex differences could be crucial for a complete understanding of this disease. We propose that the human population could be studied in this way. Sex-specific treatment strategies in human populations could show a differential response to the therapeutic approach.
Pages 657-667
Walter Struhal*, Christoph Mahringer*, Heinz Lahrmann, Christoph Mörtl, Peter Buhl, Mario Huemer, Gerhard Ransmayr *These authors contributed equally to this work.
Heart Rate Spectra Confirm the Presence of Autonomic Dysfunction in Dementia Patients
Abstract: Recent data suggest autonomic dysfunction in patients suffering dementia. This study evaluated autonomic modulation in dementia patients with and without autonomic involvement, employing ECG spectral analysis in the time-frequency domain (wavelet transform) in supine resting and head-up tilt (HUT) position. Thirty-six patients were prospectively evaluated at the Department of Neurology and Psychiatry, General Hospital of the City of Linz, between 2009 and 2014. A standard cardiovascular autonomic test series (Ewing battery) was performed to screen for autonomic dysfunction. The Ewing battery diagnoses were used as reference standard and compared to the diagnostic results obtained by spectral analysis (time-frequency domain) of ECG recordings. Based on the Ewing battery results, 14 patients suffered autonomic dysfunction, while 22 did not. Time frequency domain was accessed by using the continuous wavelet transformation (CWT) with an analytical Morlet mother wavelet in supine resting and HUT position. Within each cohort the modification of spectral components from supine resting to HUT was analyzed reflecting the autonomic modulation. For patients without autonomic dysfunction, a significant increase of autonomic modulation was detected by wavelet transformed ECG recordings (8%, p<0.05; low frequency content) during HUT compared to supine resting. There was no significant modulation between HUT and supine resting in patients suffering autonomic dysfunction. In dementia patients suffering autonomic dysfunction, CWT identified blunted autonomic regulation only by analysis of ECG recordings without the need to assess other biosignals or tests depending on the patient’s cooperation. Further studies are needed to evaluate whether CWT is a suitable method to support the standard Ewing battery in demented patients.
Pages 669-678
Brenna C. Beckelman, Stephen Day, Xueyan Zhou, Maggie Donohue , Gunnar K. Gouras, Eric Klann, C. Dirk Keene, Tao Ma (Handling Associate Editor: Jungsu Kim)
Dysregulation of Elongation Factor 1A Expression is Correlated with Synaptic Plasticity Impairments in Alzheimer’s Disease
Abstract: Synaptic dysfunction may represent an early and crucial pathophysiology in Alzheimer’s disease (AD). Recent studies implicate a connection between synaptic plasticity deficits and compromised capacity of de novo protein synthesis in AD. The mRNA translational factor eukaryotic elongation factor 1A (eEF1A) is critically involved in several forms of long-lasting synaptic plasticity. By examining postmortem human brain samples, a transgenic mouse model, and application of synthetic human Aβ42 on mouse hippocampal slices, we demonstrated that eEF1A protein levels were significantly decreased in AD, particularly in the hippocampus. In contrast, brain levels of eukaryotic elongation factor 2 were unaltered in AD. Further, upregulation of eEF1A expression by the adenylyl cyclase activator forskolin, which induces long-lasting synaptic plasticity, was blunted in hippocampal slices derived from Tg2576 AD model mice. Finally, Aβ-induced hippocampal long-term potentiation defects were alleviated by upregulation of eEF1A signaling via brain-specific knockdown of the gene encoding tuberous sclerosis 2. In summary, our findings suggest a strong correlation between the dysregulation of eEF1A synthesis and AD-associated synaptic failure. These findings provide insights into the understanding of molecular mechanisms underlying AD etiology and may aid in identification of novel biomarkers and therapeutic targets.
Pages 679-690
Qing Yu*, Du Fang*, Russell Howard Swerdlow, Haiyang Yu, John Xi Chen, Shirley ShiDu Yan (Handling Associate Editor: P. Hemachandra Reddy) *These authors contributed equally to this work.
Antioxidants Rescue Mitochondrial Transport in Differentiated Alzheimer’s Disease Trans-Mitochondrial Cybrid Cells
Abstract: Mitochondrial dysfunction and axonal degeneration are early pathological features of Alzheimer’s disease (AD)-affected brains. The underlying mechanisms and strategies to rescue it have not been well elucidated. Here, we evaluated axonal mitochondrial transport and function in AD subject-derived mitochondria. We analyzed mitochondrial transport and kinetics in human trans-mitochondrial “cybrid” (cytoplasmic hybrid) neuronal cells whose mitochondria were derived from platelets of patients with sporadic AD and compared these AD cybrid cell lines with cybrid cell lines whose mitochondria were derived from age-matched, cognitively normal subjects. Human AD cybrid cell lines, when induced to differentiate, developed stunted projections. Mitochondrial transport and function within neuronal processes/axons was altered in AD-derived mitochondria. Antioxidants reversed deficits in axonal mitochondrial transport and function. These findings suggest that antioxidants may be able to mitigate the consequences of AD-associated mitochondrial dysfunction. The present study provides evidence of the cause/effect of AD specific mitochondrial defects, which significantly enhances our understanding of the AD pathogenesis and exploring the effective therapeutic strategy for AD.
Pages 691-705
Hans-W. Klafki*, Henning Hafermann*, Chris Bauer, Ute Haussmann, Inga Kraus, Johannes Schuchhardt, Stephan Muck, Norbert Scherbaum, Jens Wiltfang *These authors contributed equally to this work.
Validation of a Commercial Chemiluminescence Immunoassay for the Simultaneous Measurement of Three Different Amyloid-β Peptides in Human Cerebrospinal Fluid and Application to a Clinical Cohort
Abstract: A comprehensive assay validation campaign of a commercially available chemiluminescence multiplex immunoassay for the simultaneous measurement of the amyloid-β peptides Aβ38, Aβ40, and Aβ42 in human cerebrospinal fluid (CSF) is presented. The assay quality parameters we addressed included impact of sample dilution, parallelism, lower limits of detection, lower limits of quantification, intra- and inter-assay repeatability, analytical spike recoveries, and between laboratory reproducibility of the measurements. The assay performed well in our hands and fulfilled a number of predefined acceptance criteria. The CSF levels of Aβ40 and Aβ42 determined in a clinical cohort (n = 203) were statistically significantly correlated with available ELISA data of Aβ1-40 (n = 158) and Aβ1-42 (n = 179) from a different laboratory. However, Bland-Altman method comparison indicated systematic differences between the assays. The data presented here furthermore indicate that the CSF concentration of Aβ40 can surrogate total CSF Aβ and support the hypothesis that the Aβ42/Aβ40 ratio outperforms CSF Aβ42 alone as a biomarker for Alzheimer’s disease due to a normalization to total Aβ levels.
Pages 707-716
Svetlana Hakobyan, Katharine Harding, Mohammed Aiyaz, Abdul Hye, Richard Dobson, Alison Baird, Benjamine Liu, Claire Louise Harris, Simon Lovestone, Bryan Paul Morgan
Complement Biomarkers as Predictors of Disease Progression in Alzheimer’s Disease
Abstract: There is a critical unmet need for reliable markers of disease and disease course in mild cognitive impairment (MCI) and early Alzheimer’s disease (AD). The growing appreciation of the importance of inflammation in early AD has focussed attention on inflammatory biomarkers in cerebrospinal fluid or plasma; however, non-specific inflammation markers have disappointed to date. We have adopted a targeted approach, centered on an inflammatory pathway already implicated in the disease. Complement, a core system in innate immune defense and potent driver of inflammation, has been implicated in pathogenesis of AD based on a confluence of genetic, histochemical, and model data. Numerous studies have suggested that measurement of individual complement proteins or activation products in cerebrospinal fluid or plasma is useful in diagnosis, prediction, or stratification, but few have been replicated. Here we apply a novel multiplex assay to measure five complement proteins and four activation products in plasma from donors with MCI, AD, and controls. Only one complement analyte, clusterin, differed significantly between control and AD plasma (controls, 295 mg/l; AD, 388 mg/l: p<10-5). A model combining clusterin with relevant co-variables was highly predictive of disease. Three analytes (clusterin, factor I, terminal complement complex) were significantly different between MCI individuals who had converted to dementia one year later compared to non-converters; a model combining these three analytes with informative co-variables was highly predictive of conversion. The data confirm the relevance of complement biomarkers in MCI and AD and build the case for using multi-parameter models for disease prediction and stratification.
Pages 717-721
Sara M.G. Cioffi, Daniela Galimberti, Federica Barocco, Marco Spallazzi, Chiara Fenoglio, Maria Serpente, Marina Arcaro, Simona Gardini, Elio Scarpini, Paolo Caffarra (Handling Associate Editor: Marco Bozzali)
Non Fluent Variant of Primary Progressive Aphasia Due to the Novel GRN g.9543delA(IVS3-2delA) Mutation
Abstract: Mutations in progranulin gene (GRN) are a common cause of autosomal dominant frontotemporal lobar degeneration syndromes and are associated with a wide phenotypic heterogeneity. The majority of genetic defects in GRN consists of loss-of-function mutations, causing haploinsufficiency, and is associated with extremely low plasma progranulin levels. Herein, we describe a patient who developed language dysfunctions and memory disturbances at 63 years of age. Considering the early onset and the positive family history (sister aged 50 with non-fluent/agrammatic variant of primary progressive aphasia, father with behavioral disturbances in his sixties), a genetic analysis was carried out, showing the presence of a novel mutation [g.9543delA (IVS3-2delA)] in a predicted splicing site of GRN. Her progranulin plasma levels were under the reference threshold, as in her sister, thus supporting the causative role of the new variant. The same genetic mutation was confirmed by sequencing in her sister. Results described enlarge current knowledge on genetic causes of the disease and clinical characteristics of carriers.
Pages 723-735
Ines Blockx*, Steve Einstein*, Pieter-Jan Guns, Johan Van Audekerke, Caroline Guglielmetti, Wagner Zago, Dimitri Roose, Marleen Verhoye, Annemie Van der Linden, Frederique Bard *These authors contributed equally to this work.
Monitoring Blood-Brain Barrier Integrity Following Amyloid-β Immunotherapy Using Gadolinium-Enhanced MRI in a PDAPP Mouse Model
Abstract: Background: Amyloid-related imaging abnormalities (ARIA) have been reported with some anti-amyloid-β (Aβ) immunotherapy trials. They are detected with magnetic resonance imaging (MRI) and thought to represent transient accumulation of fluid/edema (ARIA-E) or microhemorrhages (ARIA-H). Although the clinical significance and pathophysiology are unknown, it has been proposed that anti-Aβ immunotherapy may affect blood-brain barrier (BBB) integrity. Objective: To examine vascular integrity in aged (12-16 months) PDAPP and wild type mice (WT), we performed a series of longitudinal in vivo MRI studies. Methods: Mice were treated on a weekly basis using anti-Aβ immunotherapy (3D6) and follow up was done longitudinally from 1-12 weeks after treatment. BBB-integrity was assessed using both visual assessment of T1-weighted scans and repeated T1 mapping in combination with gadolinium (Gd-DOTA). Results: A subset of 3D6 treated PDAPP mice displayed numerous BBB disruptions, whereas WT and saline-treated PDAPP mice showed intact BBB integrity under the conditions tested. In addition, the contrast induced decrease in T1 value was observed in the meningeal and midline area. BBB disruption events occurred early during treatment (between 1 and 5 weeks), were transient, and resolved quickly. Finally, BBB-leakages associated with microhemorrhages were confirmed by Perls’ Prussian blue histopathological analysis. Conclusion: Our preclinical findings support the hypothesis that 3D6 leads to transient leakage from amyloid-positive vessels. The current study has provided valuable insights on the time course of vascular alterations during immunization treatment and supports further research in relation to the nature of ARIA and the utility of in vivo repeated T1 MRI as a translational tool.
Pages 737-750
Ilaria Luccarini*, Daniela Pantano*, Pamela Nardiello*, Leonardo Cavone, Andrea Lapucci, Caterina Miceli, Chiara Nediani, Andrea Berti, Massimo Stefani, Fiorella Casamenti (Handling Associate Editor: Tommaso Cassano) *These authors contributed equally to this work.
The Polyphenol Oleuropein Aglycone Modulates the PARP1-SIRT1 Interplay: An In Vitro and In Vivo Study
Abstract: poly(ADP-ribose) polymerase-1 (PARP1) activation contributes to the cascade of events initiated by amyloid-β (Aβ) peptide eventually leading to cell death in Alzheimer’s disease brain. A significant accumulation of PAR polymers and increase of PARP1 expression were detected in the cortex at the early (3.5 months) and intermediate (6 months) stage of Aβ deposition in the TgCRND8 mouse model. Our previous data highlighted the beneficial effects of oleuropein aglycone (OLE), the main polyphenol found in the olive oil, against neurodegeneration both in cultured cells and in model organisms. Here we found that 8-week OLE treatment (50 mg/kg of diet) to 6-month-old TgCRND8 mice rescued to control values PARP1 activation and the levels of its product, PAR. In N2a neuroblastoma cells, PARP1 activation and PAR formation upon exposure to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were abolished by pretreatment for 24 h with either OLE (100 μM) or PARP inhibitors. A significant reduction of the NAD+ content, compared to controls, was found in N2a cells exposed to MNNG (100 µM) for 90 min; the latter was slightly attenuated by cell treatment for 24 h with PJ-34 or with OLE. In vitro and in vivo, the OLE-induced reduction of PARP1 activation was paralleled by the overexpression of Sirtuin1 (SIRT1), and, in vivo, by a decrease of NF-kB and the pro-apoptotic marker p53. In N2a cells, we also found that OLE potentiates the MNNG-induced increase of Beclin1 levels. In conclusion, our data show that OLE treatment counteracts neuronal damage through modulation of the PARP1-SIRT1 interplay.
Pages 751-762
Virginia Pérez-Grijalba*, Noelia Fandos*, Jesús Canudas, Daniel Insua, Diego Casabona, Ana M. Lacosta, María Montañés, Pedro Pesini, Manuel Sarasa *These two authors contributed equally to this work.
Validation of Immunoassay-Based Tools for the Comprehensive Quantification of Aβ40 and Aβ42 Peptides in Plasma
Abstract: Recent advances in neuroimaging and cerebrospinal fluid (CSF) biomarker assays have provided evidence of a long preclinical stage of Alzheimer’s disease (AD). This period is being increasingly targeted for secondary prevention trials of new therapies. In this context, the interest of a noninvasive, cost-effective amyloid-β (Aβ) blood-based test does not need to be overstated. Nevertheless, a thorough validation of these bioanalytical methods should be performed as a prerequisite for confident interpretation of clinical results. The aim of this study was to validate ELISA sandwich colorimetric ABtest40 and ABtest42 for the quantification of Aβ40 and Aβ42 in human plasma. The validation parameters assessed included precision, accuracy, sensitivity, specificity, recovery, and dilution linearity. ABtest40 and ABtest42 proved to be specific for their target peptide using Aβ peptides with sequence similar to the target. Mean relative error in the quantification was found to be below 7.5% for both assays, with high intra-assay, inter-assay, and inter-batch precision (CV<9.0% on average). Sensitivity was assessed by determination of the limit of quantification fulfilling precision and accuracy criteria; it was established at 7.60 pg/ml and 3.60 pg/ml for ABtest40 and ABtest42, respectively. Plasma dilution linearity was demonstrated in PBS; however, dilution in a proprietary formulated buffer significantly increased the recovery of both Aβ40 and Aβ42 masked by matrix interactions, allowing a more comprehensive assessment of the free and total peptide levels in the plasma. In conclusion, both assays were successfully validated as tools for the quantification Aβ40 and Aβ42 in plasma.
Pages 763-776
Alexey V. Morozov, Alexandra A. Kulikova, Tatiana M. Astakhova, Vladimir A. Mitkevich, Ksenia M. Burnysheva, Alexei A. Adzhubei, Pavel A. Erokhov, Michail B. Evgen’ev, Natalia P. Sharova, Vadim L. Karpov, Alexander A. Makarov (Handling Associate Editor: Vladimir Buchman)
Amyloid-β Increases Activity of Proteasomes Capped with 19S and 11S Regulators
Abstract: Accumulation of amyloid-β (Aβ) in neurons accompanies Alzheimer's disease progression. In the cytoplasm Aβ influences activity of proteasomes, the multisubunit protein complexes that hydrolyze the majority of intracellular proteins. However, the manner in which Aβ affects the proteolytic activity of proteasomes has not been established. In this study the effect of Aβ42 and Aβ42 with isomerized Asp7 on activity of different forms of proteasomes has been analyzed. It has been shown that Aβ peptides efficiently reduce activity of the 20S proteasomes, but increase activity of the 20S proteasomes capped with the 19S and/or 11S regulators. Modulation of proteasome activity is mainly determined by the C-terminal segment of Aβ (amino acids 17-42). This study demonstrated an important role of proteasome regulators in the interplay between Aβ and the proteasomes.
Pages 777-787
Andres M. Lozano, Lisa Fosdick, M. Mallar Chakravarty, Jeannie-Marie Leoutsakos, Cynthia Munro, Esther Oh, Kristen E. Drake, Christopher H. Lyman, Paul B. Rosenberg, William S. Anderson, David F. Tang-Wai, Jo Cara Pendergrass, Stephen Salloway, Wael F. Asaad, Francisco A. Ponce, Anna Burke, Marwan Sabbagh, David A. Wolk, Gordon Baltuch, Michael S. Okun, Kelly D. Foote, MaryPat McAndrews, Peter Giacobbe, Steven D. Targum, Constantine G. Lyketsos*, Gwenn Smith* *Co-equal last authors
A Phase II Study of Fornix Deep Brain Stimulation in Mild Alzheimer’s Disease
Abstract: Background: Deep brain stimulation (DBS) is used to modulate the activity of dysfunctional brain circuits. The safety and efficacy of DBS in dementia is unknown. Objective: To assess DBS of memory circuits as a treatment for patients with mild Alzheimer’s disease (AD). Methods: We evaluated active “on” versus sham “off” bilateral DBS directed at the fornix—a major fiber bundle in the brain’s memory circuit—in a randomized, double-blind trial (ClinicalTrials.gov NCT01608061) in 42 patients with mild AD. We measured cognitive function and cerebral glucose metabolism up to 12 months post-implantation. Results: Surgery and electrical stimulation were safe and well tolerated. There were no significant differences in the primary cognitive outcomes (ADAS-Cog 13, CDR-SB) in the “on” versus “off” stimulation group at 12 months for the whole cohort. Patients receiving stimulation showed increased metabolism at 6 months but this was not significant at 12 months. On post-hoc analysis, there was a significant interaction between age and treatment outcome: in contrast to patients
Pages 789-791
Commentary
Itzhak Fried
Brain Stimulation in Alzheimer’s Disease
Abstract: Deep brain stimulation has been successfully used in treatment of motor symptoms of Parkinson’s disease and other movement disorders. In a recent multi-center prospectively randomized study, deep brain stimulation of the fornix was administered in order to ameliorate the cognitive symptoms and clinical course of Alzheimer’s disease (AD). The study points to the possibility of modest slowing of the cognitive decline in AD in a subset of patients older than 65, while at the time highlights the risk of stimulation in exacerbation of this decline in younger patients. The logic of conducting large clinical trials at the face of limited scientific understanding of the pathophysiology of AD and response of affected brain regions to electrical stimulation, is discussed with emphasis on the need to conduct: (i) animal studies in AD models, using precise focused stimulation; (ii) studies in patients who are implanted with depth electrodes for established clinical reasons (i.e., Patients with epilepsy or movement disorders); and (iii) smaller adaptive studies in AD patients with systematic alterations of therapeutic parameters such as stimulation protocol.
Pages 793-799
Rosie E. Curiel, Elizabeth Crocco, Marian Rosado, Ranjan Duara, Maria T. Greig, Arlene Raffo, David A. Loewenstein
A Brief Computerized Paired Associate Test for the Detection of Mild Cognitive Impairment in Community-Dwelling Older Adults
Abstract: Background: Semantic memory interference has been found to be a predictive cognitive marker of incipient AD. This is relevant given that developing novel paradigms to identify subtle cognitive and functional deficits is a priority in preclinical Alzheimer’s disease research. Objective: To examine the utility of a novel computerized paired associate test in distinguishing between mild cognitive impairment (MCI) and cognitively normal (CN) groups of older adults residing in the community. Methods: Participants that were CN (n = 64) or MCI (n = 34) were administered the Miami Test of Semantic Interference and Learning (MITSI-L). This novel instrument is a brief, computerized paired associate test that measured the strength of memory binding of semantically related word pairs and introduced a proactive semantic interference condition which required participants to make different associations between semantically similar targets. A series of ANOVAs explored differences on MITSI-L performance. Logistic regression and receiver operator curves (ROC) analyses were employed to further determine discriminative validity. Results: MCI participants had lower scores on all indices relative to CN elders. A composite of two subscores correctly classified 85.3% of MCI and 84.4% of CN participants. Area under the ROC was higher relative to the MMSE, immediate memory for passages, and several subtests of a sensitive memory measure, the LASSI-L. Conclusions: The MITSI-L is a computerized test that can successfully differentiate MCI from CN participants. Area under the ROC curve exceeded that of global mental status and other memory measures. The effectiveness of the MITSI-L in detecting MCI, and its brief administration and portability render it worthy of further research.
Pages 801-808
Willy Gomm, Klaus von Holt, Friederike Thomé, Karl Broich, Wolfgang Maier, Klaus Weckbecker, Anne Fink, Gabriele Doblhammer, Britta Haenisch
Regular Benzodiazepine and Z-Substance Use and Risk of Dementia: An Analysis of German Claims Data
Abstract: Background: While acute detrimental effects of benzodiazepine (BDZ), and BDZ and related z-substance (BDZR) use on cognition and memory are known, the association of BDZR use and risk of dementia in the elderly is controversially discussed. Previous studies on cohort or claims data mostly show an increased risk for dementia with the use of BDZs or BDZRs. For Germany, analyses on large population-based data sets are missing. Objective: To evaluate the association between regular BDZR use and incident any dementia in a large German claims data set. Methods: Using longitudinal German public health insurance data from 2004 to 2011 we analyzed the association between regular BDZR use (versus no BDZR use) and incident dementia in a case-control design. We examined patient samples aged ≥60 years that were free of dementia at baseline. To address potential protopathic bias we introduced a lag time between BDZR prescription and dementia diagnosis. Odds ratios were calculated applying conditional logistic regression, adjusted for potential confounding factors such as comorbidities and polypharmacy. Results: The regular use of BDZRs was associated with a significant increased risk of incident dementia for patients aged ≥60 years (adjusted odds ratio [OR] 1.21, 95% confidence interval [CI] 1.13-1.29). The association was slightly stronger for long-acting substances than for short-acting ones. A trend for increased risk for dementia with higher exposure was observed. Conclusion: The restricted use of BDZRs may contribute to dementia prevention in the elderly.
Pages 809-819
Svetlana A. Khmeleva, Sergey P. Radko, Sergey A. Kozin, Yana Y. Kiseleva, Yuri V. Mezentsev, Vladimir A. Mitkevich, Leonid K. Kurbatov, Alexis S. Ivanov, Alexander A. Makarov (Handling Associate Editor: Natalia Stefanova)
Zinc-Mediated Binding of Nucleic Acids to Amyloid-β Aggregates: Role of Histidine Residues
Abstract: Amyloid-β peptide (Aβ) plays a central role in Alzheimer’s disease (AD) pathogenesis. Besides extracellular Aβ, intraneuronal Aβ (iAβ) has been suggested to contribute to AD onset and development. Based on reported in vitro Aβ-DNA interactions and nuclear localization of iAβ, the interference of iAβ with the normal DNA expression has recently been proposed as a plausible pathway by which Aβ can exert neurotoxicity. Employing the sedimentation assay, thioflavin T fluorescence, and dynamic light scattering we have studied effects of zinc ions on binding of RNA and single- and double-stranded DNA molecules to Aβ42 aggregates. It has been found that zinc ions significantly enhance the binding of RNA and DNA molecules to pre-formed β-sheet rich Aβ42 aggregates. Another type of Aβ42 aggregates, the zinc-induced amorphous aggregates, was demonstrated to also bind all types of nucleic acids tested. To evaluate the role of the Aβ metal-binding domain’s histidine residues in Aβ-nucleic acid interactions mediated by zinc, Aβ16 mutants with substitutions H6R and H6A-H13A and rat Aβ16 lacking histidine residue 13 were used. The zinc-induced interaction of Aβ16 with DNA was shown to critically depend on histidine residues 6 and 13. However, the inclusion of H6R mutation in Aβ42 peptide did not affect DNA binding to Aβ42 aggregates. Since oxidative and/or nitrosative stresses implicated in AD pathogenesis are known to release zinc ions from metallothioneins in cytoplasm and cell nuclei, our findings suggest that intracellular zinc can be an important player in iAβ-nucleic acid interactions.
Pages 821-830
Olga M. Selivanova*, Alexey K. Surin*, Victor V. Marchenkov, Ulyana F. Dzhus, Elizaveta I. Grigorashvili, Mariya Yu. Suvorina, Anna V. Glyakina, Nikita V. Dovidchenko, Oxana V. Galzitskaya *These authors contributed equally to this work.
The Mechanism Underlying Amyloid Polymorphism is Opened for Alzheimer’s Disease Amyloid-β Peptide
Abstract: It has been demonstrated using Aβ40 and Aβ42 recombinant and synthetic peptides that their fibrils are formed of complete oligomer ring structures. Such ring structures have a diameter of about 8-9 nm, an oligomer height of about 2-4 nm, and an internal diameter of the ring of about 3-4 nm. Oligomers associate in a fibril in such a way that they interact with each other, overlapping slightly. There are differences in the packing of oligomers in fibrils of recombinant and synthetic Aβ peptides. The principal difference is in the degree of orderliness of ring-like oligomers that leads to generation of morphologically different fibrils. Most ordered association of ring-like structured oligomers is observed for a recombinant Aβ40 peptide. Less ordered fibrils are observed with the synthetic Aβ42 peptide. Fragments of fibrils the most protected from the action of proteases have been determined by tandem mass spectrometry. It was shown that unlike Aβ40, fibrils of Aβ42 are more protected, showing less ordered organization compared to that of Aβ40 fibrils. Thus, the mass spectrometry data agree with the electron microscopy data and structural models presented here.
Pages 831-843
Ivana Zimova, Veronika Brezovakova, Tomas Hromadka, Petronela Weisova, Veronika Cubinkova, Bernadeta Valachova, Peter Filipcik, Santosh Jadhav, Tomas Smolek, Norbert Zilka (Handling Associate Editor: Alejandra Alonso)
Human Truncated Tau Induces Mature Neurofibrillary Pathology in a Mouse Model of Human Tauopathy
Abstract: Alzheimer's disease (AD) represents the most common neurodegenerative disorder. Several animal models have been developed in order to test pathophysiological mechanisms of the disease and to predict effects of pharmacological interventions. Here we examine the molecular and behavioral features of R3m/4 transgenic mice expressing human non-mutated truncated tau protein (3R tau, aa151–391) that were previously used for efficacy testing of passive tau vaccine. The mouse model reliably recapitulated crucial histopathological features of human AD, such as pre-tangles, neurofibrillary tangles, and neuropil threads. The pathology was predominantly located in the brain stem. Transgenic mice developed mature sarkosyl insoluble tau complexes consisting of mouse endogenous and human truncated and hyperphosphorylated forms of tau protein. The histopathological and biochemical features were accompanied by significant sensorimotor impairment and reduced lifespan. The sensorimotor impairment was monitored by a highly sensitive, fully-automated tool that allowed us to assess early deficit in gait and locomotion. We suggest that the novel transgenic mouse model can serve as a valuable tool for analysis of the therapeutic efficacy of tau vaccines for AD therapy.
