Pages 331-343
Review
Lucy Nelson, Paul Gard, Naji Tabet
Hypertension and Inflammation in Alzheimer’s Disease: Close Partners in Disease Development and Progression!
Abstract: Alzheimer’s disease (AD) is by far the most common sporadic neurodegenerative disorder. Clinically it is associated with cognitive and other neuropsychological impairments, and neuropathologically it is distinguished by presence of amyloid-β plaques and neurofibrillary tangles. Hypertension has been traditionally associated with the etiology of vascular dementia, however, vascular risk factors including hypertension are increasingly being implicated in AD. Likewise, the importance of neuroinflammation in AD pathogenesis is also widely recognized. Data from animal and non-AD human studies suggest a close reciprocal relationship between hypertension and inflammatory systems. Much less is known on the potential pathological interaction between hypertension and inflammation in AD and its subsequent effects on amyloid and tau misfolding, aggregation, and propagation, events recognized as critical for the development and progression of AD. This review summarizes what is known about the mechanistic interactions between hypertension and inflammatory mediators and assesses their potential synergistic/additive role in AD genesis. Increasing our understanding of the pathological interactions between the recognized risk factors for AD is a worthwhile endeavor in a condition which currently has limited treatment options but an increasing number of potential preventative measures.
Pages 345-364
Review
Claire L. Russell, Sasa Koncarevic, Malcolm A. Ward (Handling Associate Editor: Carol Brayne)
Post-Translational Modifications in Alzheimer’s Disease and the Potential for New Biomarkers
Abstract: The ability to detect and diagnose Alzheimer’s disease (AD) early is an ever pressing issue, and the development of markers of disease progression that are able to distinguish AD patients from normal aging and patients with alternative forms of dementia, is at the center of the issue. Protein markers of disease, or biomarkers, can be used not only to monitor the progression of AD, but also allow identification of patients suitable for potential therapy, and the response to therapy to be monitored. Cerebrospinal fluid protein biomarkers are important in this early AD diagnosis, and three such biomarkers have been extensively studied and are reviewed here. In addition, post translational protein modifications of proteins important in AD pathology are also discussed. If additional biomarkers can be identified and thoroughly understood, potential therapeutic agents can be better designed, and the effects of therapeutic intervention on disease progression can be monitored.
Pages 365-369
Short Communication
Marta Anne Taddeo, Sangmook Lee, Thomas B. Shea
Synergistic Inhibition of Synaptic Signaling in Cortical Cultures by Subcytotoxic Levels of Oligomerized Amyloid-β and Iron: Alleviation by Zinc
Abstract: Iron exacerbates amyloid-β (Aβ) toxicity, while zinc alleviates it. We examined the impact of these metals on Aβ-induced signaling inhibition. Murine embryonic cortical neurons on multi-electrode arrays received 0.1 µM FeCl2 0.1 µM zinc acetate and/or 10 nM oligomerized Aβ1-42. No toxicity was observed. Spontaneous signaling was not altered by iron or Aβ individually, but was inhibited by both. Zinc did not impact signaling alone, but prevented inhibition by iron plus Aβ. Aβ can be detected years before cognitive decline. Subcytotoxic iron levels may potentiate Aβ-induced impairment of synaptic activity during these early stages; zinc supplementation may alleviate this potentiation.
Pages 371-376
Barbara Borroni, Mario Grassi, Marta Bianchi, Amalia Cecilia Bruni, Raffaele Giovanni Maletta, Maria Anfossi, Daniele Pepe, Annachiara Cagnin, Paolo Caffarra, Stefano Cappa, Francesca Clerici, Antonio Daniele, Giovanni B. Frisoni, Daniela Galimberti, Lucilla Parnetti, Roberta Perri, Innocenzo Rainero, Lucio Tremolizzo, Marinella Turla, Orazio Zanetti, Alessandro Padovani (Handling Associate Editor: Valeria Drago)
Estimating the Inheritance of Frontotemporal Lobar Degeneration in the Italian Population
Abstract: Frontotemporal dementia (FTD) has a strong genetic basis, with familial forms occurring in 30-50% of cases. Causative genes have been identified, with an autosomal dominant pattern of inheritance. Notwithstanding, in a number of cases with positive family history no pathogenetic mutation has been reported, and the role of genetics in sporadic cases is still unclear. In the present study, we aim to estimate the genetic contribution to FTD using concordance among parent-offspring pairs. Heritability of early-onset (EO, <65 years) and late-onset (LO, ≥65 years) FTD was estimated by examining the concordance between parents and offspring. Probands with at least one parent whose dementia status was known were recruited from 15 Italian centers, and the presence or absence of dementia was considered in siblings. Different prevalence estimates, as available by literature data, were tested. A total of 260 probands and 1619 family members were considered in this study. We found that parent-offspring concordance in FTD was 6.25%, resulting in hereditability of 98.5% (95% confidence interval (CI): 85.0%-100.0%). Equal heritability for both sexes regardless of parental gender was reported. EO-FTD showed hereditability of 86.3% (95% CI: 77.0%-95.0%) and LO-FTD of 75.7% (95% CI: 65.0%-86.0%). Estimating the contribution of genetics in FTD may help in driving future genetic studies to identify new pathogenetic determinants. We suggest that in most of the cases FTD is a genetic-based disease, even in the elderly. Different inheritance modality might be considered in future work, beyond autosomal dominant disease.
Pages 377-386
Mathilde Sauvée, Guerric DidierLaurent, Clotilde Latarche, Marie-Christine Escanyé, Jean-Luc Olivier, Catherine Malaplate-Armand
Additional Use of Aβ42/Aβ40 Ratio with Cerebrospinal Fluid Biomarkers P-Tau and Aβ42 Increases the Level of Evidence of Alzheimer’s Disease Pathophysiological Process in Routine Practice
Abstract: Background. Cerebrospinal fluid (CSF) biomarkers have recently been included in the criteria for the diagnosis of Alzheimer’s disease (AD). Since interpretation of CSF profile requires the combination of three parameters, biological data are not always conclusive and isolated elevation of phosphorylated tau (P-tau) or reduction of amyloid-β (Aβ)42 alone can be observed. In these cases, Aβ42/Aβ40 ratio could be more relevant than Aβ42 absolute values by considering inter-individual variations in the total amyloid load. Objective. The objective of this study was to assess the use of Aβ42/Aβ40 ratio to improve the accuracy of biological conclusions in the diagnosis of patients with ambiguous CSF Aβ42 or tau results. Methods. Among 386 lumbar punctures analyzed in the lab in 2 years, 122 showed ambiguous biological data that were completed by CSF Aβ40 quantification and Aβ42/Aβ40 ratio calculation. A biological conclusion was then made using 0.05 as the Aβ42/Aβ40 ratio cut-off. Results. Our results showed that one-third of the biological profiles of patients with atypical dementia were ambiguous. The addition of Aβ42/Aβ40 ratio increased the proportion of interpretable biological profiles from 69% to 87%, without changing the conclusion when usual biomarkers (Aβ42 and P-tau) were concordant. Conclusion. Our results support the use of the Aβ42/Aβ40 ratio in addition to the usual CSF AD biomarkers for patients with ambiguous biological profiles. This method could be specifically directed to this population in order to improve the level of certainty for clinical routine practice.
Pages 387-399
Vivek Tiwari, Anant B. Patel
Pyruvate Carboxylase and Pentose Phosphate Fluxes are Reduced in AβPP-PS1 Mouse Model of Alzheimer's Disease: A 13C NMR Study
Abstract: Although pyruvate dehydrogenase (PDH) is the major pathway of glucose metabolism and source for energy production, pyruvate carboxylase (PC) and pentose phosphate pathway (PPP) account for a significant fraction of glucose oxidation in the mature central nervous system. Flux through the PDH pathway has been reported to be reduced in Alzheimer’s disease (AD) patients as well as in animal models of AD. However, fluxes through the PPP and PC pathways have not been explored under conditions of AD. The present study investigates the fluxes of PC and PPP in a 20-month-old AβPP-PS1 mouse model of AD using 13C NMR spectroscopy together with infusion of [2-13C]glucose. Mice were also administered [1,6-13C2]glucose or [1-13C]glucose for 10 or 90 min, respectively, to investigate PDH flux. AβPP-PS1 mice exhibit a significant reduction in the level of NAA and increase in level of myo-inositol. The flux through PDH was found to be significantly lower in the cerebral cortex (AβPP-PS1 0.39±0.08; control 0.77±0.08 µmol/g/min), hippocampus (AβPP-PS1 0.31±0.04; control 0.64±0.12 µmol/g/min), and striatum (AβPP-PS1 0.34±0.06; control 0.56±0.03 µmol/g/min) of AβPP-PS1 as compared with control mice. The fluxes through PC (AβPP-PS1 0.037±0.006, control 0.079±0.013 µmol/g/min) and PPP (AβPP-PS1 0.024±0.005; control 0.062±0.022 µmol/g/min) were found to be significantly reduced in AβPP-PS1 mice when compared with age-matched controls. The reduction in the fluxes of PC and PPP may lead to a weakened neural defense system of ammonia detoxification and antioxidant reserve in AβPP-PS1 mice, which may be responsible for the compromised neuronal viability and functions in AD.
Pages 401-410
Giovanna Viticchi, Lorenzo Falsetti, Fabrizio Vernieri, Claudia Altamura, Riccardo Altavilla, Simona Luzzi, Marco Bartolini, Leandro Provinciali, Mauro Silvestrini (Handling Associate Editor: Jack de la Torre)
Apolipoprotein E Genotype and Cerebrovascular Alterations Can Influence Conversion to Dementia in Patients with Mild Cognitive Impairment
Abstract: The presence of apolipoprotein E (APOE) ε4 allele is the only recognized genetic risk factor for the sporadic form of Alzheimer’s disease. The aim of this study was to investigate the relationship between APOE genotype and the functional and anatomic status of cerebral vessels in patients with mild cognitive impairment (MCI). Moreover, we explored whether the possible correlation between APOE genotype and cerebrovascular parameters influences the risk of conversion from MCI to dementia. 75 MCI patients underwent a complete neuropsychological battery at baseline and after 24 months to evaluate the possible conversion to dementia. Ultrasound assessment of neck and intracranial vessels was performed to assess common carotid artery intima-media thickness (IMT), plaque index, and cerebrovascular reactivity (breath-holding index, BHI). APOE genotype was determined to classify patients as carriers (APOE ε4+) and non-carriers (APOE ε4-). Pathologic values of BHI and IMT were significantly more common in ε4 carriers than in non-carriers [OR 6.603 (95% CI 1.678-25.997), p<0.05 and OR 5.195 (95% CI 1.319-20.464), p<0.05; logistic regression adjusted model]. The risk of conversion to dementia was significantly higher in APOE ε4+ patients than in APOE ε4- ones (OR: 6.818; 95% CI:1.894-24.545, p=0.003). A path-analysis model showed that APOE genotype influences the progression to dementia directly and indirectly by increasing the risk of pathologic values of IMT or BHI. Our data, besides confirming an increased susceptibility of MCI patients with APOE ε4 to develop dementia, show an association between functional and anatomic impairment of the cerebral vessels and APOE ε4+ genotype.
Pages 411-419
Hanna Eriksson, Seyed-Mohammad Fereshtehnejad, Farshad Falahati, Bahman Farahmand, Dorota Religa, Maria Eriksdotter (Handling Associate Editor: Josep Garre-Olmo)
Differences in Routine Clinical Practice between Early and Late Onset Alzheimer’s Disease: Data from the Swedish Dementia Registry (SveDem)
Abstract: Background: Due to age of onset, Alzheimer’s disease (AD) is divided into early onset (EOAD) or late onset (LOAD), but emerging data also suggests that the underlying pathology may be different. Whether differences in clinical care exist is less well investigated. Objectives: To evaluate whether there are differences in demographics, diagnostic work-up, and pharmacological treatment between EOAD and LOAD. Material and Methods: Data on patients with newly diagnosed EOAD (n=453) and LOAD (n=4599) was obtained from the Swedish dementia registry (SveDem). Logistic regression models were used to adjust the comparisons for the baseline confounders including gender, cognitive decline, and co-morbidity. Results: The majority of EOAD and LOAD were in the mild stage of the disease when diagnosed. The majority of patients with EOAD went through an extended diagnostic work-up including more technical investigations as well as assessments by neuropsychologists and speech therapists than patients with LOAD. EOAD patients were treated with overall fewer medications but obtained treatment with cholinesterase inhibitors to a higher extent than those with LOAD, while there were no differences between the groups in antidepressant and antipsychotics use. Conclusions: There are differences between EOAD and LOAD in demographics, diagnostic work-up, and pharmacological treatment. Based on our findings, an extensive work-up should be recommended when EOAD is suspected.
Pages 421-430
Erin L. Boespflug, James Eliassen, Jeffrey Welge, Robert Krikorian (Handling Associate Editor: Peter Bayley)
Associative Learning and Regional White Matter Deficits in Mild Cognitive Impairment
Abstract: Background: While diagnostic criteria for Alzheimer’s disease (AD) include neuroimaging biomarkers, there remains no definitive biomarker of mild cognitive impairment (MCI). MCI is a risk factor for AD that may be amenable to early intervention. Early decline in white matter (WM) integrity identified by diffusion tensor imaging is a predictor of future progression of neurodegeneration. Objective: Identify regionally specific WM differences between individuals with MCI and those with age-associated memory impairment (AAMI) and relationships with specific memory decrements. Methods: DTI and neuropsychological data were acquired from 38 participants (23 MCI and 15 AAMI). A region of interest approach was used to evaluate regional differences between groups and correlative relationships with performance on memory tasks. Results: Fornix WM had higher mean (MD), radial (DR), and axial (DA) diffusivity in MCI participants relative to AAMI. Temporal stem (TS) WM had higher MD and DR in MCI than in AAMI. In MCI, TS MD and DR varied, while fornix MD and DR was uniformly high, and in AAMI, TS MD and DR were uniformly low and fornix MD and DR varied. In MCI, TS MD and DA were inversely associated with associative learning but not list learning. Conclusions: In addition to supporting prior evidence implicating the fornix in early AD pathology, these data implicate a profile of neurodegeneration associated with early MCI. Further, they suggest that associative learning tasks are more sensitive to early neurodegeneration and may be useful in identifying individuals at risk for AD.
Pages 431-439
Jean-Baptiste Mignardot, Olivier Beauchet, Cédric Annweiler, Christophe Cornu, Thibault Deschamps (Handling Associate Editor: Eija Lönnroos)
Postural Sway, Falls, and Cognitive Status: A Cross-Sectional Study among Older Adults
Abstract: Background: Cognitive impairment-related changes in postural sway increase fall risk among older adults. Better understanding this association could be helpful for fall prevention. Objective: To examine the center-of-pressure (COP) velocity association with cognitive status and history of falls, in cognitively healthy individuals (CHI), patients with mild cognitive impairment (MCI), and with mild-to-moderate Alzheimer’s disease (MMAD). Methods: Six hundred and eleven older community-dwellers (77.2 ± 7.9 years; 51.8% men) were separated into CHI, MCI, and MMAD participants. By computing the average absolute maximal velocity (AAMV), the bounding limits of COP velocity dynamics were determined while participants were asked to maintain quiet stance on a force platform with eyes open or with eyes closed. Age, gender, history of falls, body mass index, handgrip strength, Timed Up & Go score were used as covariates. Results: The multivariate ANCOVA, with AAMV in eyes open and eyes closed conditions as dependent variables, showed that the highest AAMVs that bound the COP velocity dynamics of postural sway were associated with cognitive impairment (p = 0.048) (i.e., lowest limits in CHI and MCI as compared with MMAD) and falls (p = 0.033) (i.e., highest limits in fallers). Conclusions: These findings identified the bounding limits of COP velocity as a hallmark feature of cognitive impairment-related changes in postural sway, in particular for MMAD. This point is of special interest for clinical balance assessment and fall prevention in MMAD patients in order to plan long-term targeted fall-prevention programs.
Pages 441-451
Magdalena Korecka, Teresa Waligorska, Michal Figurski, Jon B Toledo, Steven E. Arnold, Murray Grossman, John Q. Trojanowski, Leslie M. Shaw (Handling Associate Editor: Piotr Lewczuk)
Qualification of a Surrogate Matrix-Based Absolute Quantification Method for Amyloid-β42 in Human Cerebrospinal Fluid Using 2D UPLC-Tandem Mass Spectrometry
Abstract: The primary aims of this work were to: 1) establish a calibrator surrogate matrix for quantification of amyloid-β (Aβ)42 in human cerebrospinal fluid (CSF) and preparation of quality control samples for LC-MS-MS methodology, 2) validate analytical performance of the assay, and 3) evaluate its diagnostic utility and compare it with the AlzBio3 immunoassay. The analytical methodology was based on a 2D-UPLC-MS-MS platform. Sample pretreatment used 5 M guanidine hydrochloride and extraction on μElution SPE columns as previously described. A column cleaning procedure involved gradual removal of aqueous solvents by acetonitrile assured consistent long-term chromatography performance. Receiver-operator characteristic (ROC) curve and correlation analyses evaluated the diagnostic utility of UPLC-MS-MS compared to AlzBio3 immunoassay for detection of Alzheimer’s disease (AD). The surrogate matrix, artificial CSF containing 4 mg/mL of BSA, provides linear and reproducible calibration comparable to human pooled CSF as calibration matrix. Appropriate cleaning of the trapping and analytical columns provided every-day, trouble-free runs. Analyses of CSF Aβ42 showed that UPLC-MS-MS distinguished neuropathologically-diagnosed AD subjects from healthy controls with at least equivalent diagnostic utility to AlzBio3. Comparison of ROC curves for these two assays showed no statistically significant difference (p = 0.2229). Linear regression analysis of Aβ42 concentrations measured by this mass spectrometry-based method compared to the AlzBio3 immunoassay showed significantly higher but highly correlated results. In conclusion, the newly established surrogate matrix for 2D-UPLC-MS-MS measurement of Aβ42 provides selective, reproducible, and accurate results. The documented analytical performance and diagnostic performance for AD versus controls supports consideration as a candidate reference method.
Pages 453-466
Lorena Rami, Maria A. Mollica, Carmen García-Sanchez, Judith Saldaña4, Belen Sanchez, Isabel Sala, Cinta Valls-Pedret, Magda Castellví, Jaume Olives, Jose L Molinuevo (Handling Associate Editor: Montse Alegret)
The Subjective Cognitive Decline Questionnaire (SCD-Q): a validation study
Abstract: Background: Subjective cognitive decline (SCD) is gaining importance as a focus of investigation, but adequate tools are needed for its quantification. Objective: To develop and validate a questionnaire to quantify SCD, termed the Subjective Cognitive Decline Questionnaire (SCD-Q). Methods: 124 controls (CTR), 144 individuals with SCD, 83 mild cognitive impairment subjects, 46 Alzheimer’s disease patients, and 397 informants were included. The SCD-Q contains: part I, named MyCog, which is answered by the subject; and part II, TheirCog, which includes the same questions and is answered by the informant or caregiver. The 24 SCD-Q items assess the perceived subjective decline in memory, language, and executive functions in the last two years. Results: The MyCog scores of controls differed significantly from those of the other groups (p<0.05) and there were significant differences in TheirCog scores between all groups. The optimal TheirCog cut-off score for discriminating between individuals with and without cognitive impairment was 7/24 (sensitivity 85%, specificity 80%). MyCog scores correlated significantly with anxiety and depression (r=0.29, r=0.43, p<0.005), but no correlations were found with neuropsychological tests. TheirCog scores correlated significantly with most of the neuropsychological tests (p<0.05). Informants’ depression and anxiety influenced TheirCog scores in controls and SCD groups. Conclusion: Self-perceived cognitive decline, measured by the SCD-Q part I (MyCog), discriminated SCD from CTR. Part II (TheirCog) was strongly related to subjects’ objective cognitive performance, and discriminated between subjects with or without cognitive impairment. The SCD-Q is a useful tool to measure self-perceived cognitive decline incorporating the decliner and the informant perspective.
Pages 467-477
Sara García-Ptacek, Bahman Farahmand, Ingemar Kåreholt, Dorota Religa, Maria Luz Cuadrado, Maria Eriksdotter (Handling Associate Editor: Alberto Villarejo)
Mortality Risk after Dementia Diagnosis by Dementia Type and Underlying Factors: A Cohort of 15,209 Patients based on the Swedish Dementia Registry
Abstract: Background: Knowledge on survival in dementia is crucial for patients and public health planning. Most studies comparing mortality risk included few different dementia diagnoses. Objectives: To compare mortality risk in the most frequent dementia disorders in a large cohort of patients with an incident diagnosis, adjusting for potential confounding factors. Methods: 15,209 patients with dementia from the national quality database, Swedish Dementia Registry (SveDem), diagnosed in memory clinics from 2008 to 2011, were included in this study. The impact of age, gender, dementia diagnosis, baseline Mini-Mental State Examination (MMSE), institutionalization, coresidency, and medication on survival after diagnosis were examined using adjusted hazard ratios (HR) with 95% confidence intervals (CI). Results: During a mean follow-up of 2.5 years, 4,287 deaths occurred, with 114 (95% CI 111-117) deaths/1,000 person-years. Adjusted HR of death for men was 1.56 (95% CI 1.46-1.66) compared to women. Low MMSE, institutionalization, and higher number of medications were associated with higher HR of death. All dementia diagnoses demonstrated higher HR compared to Alzheimer’s disease, with vascular dementia presenting the highest crude HR. After adjusting, frontotemporal dementia had the highest risk with a HR of 1.91 (95% CI 1.52-2.39), followed by Lewy body dementia (HR 1.64; 95% CI 1.39-1.95), vascular dementia (HR 1.55; 95% CI 1.42-1.69), Parkinson’s disease dementia (HR 1.47; 95% CI 1.17-1.84), and mixed Alzheimer’s disease and vascular dementia (HR 1.32; 95% CI 1.22-1.44). Conclusion: Worse cognition, male gender, higher number of medications, institutionalization, and age were associated with increased death risk after dementia diagnosis. Adjusted risk was lowest in Alzheimer’s disease patients and highest in frontotemporal dementia subjects.
Pages 479-497
Martha Dlugaj, Gerhard Weinreich, Christian Weimar, Andreas Stang, Nico Dragano, Thomas E. Wessendorf, Helmut Teschler, Angela Winkler, Natalia Wege, Susanne Moebus, Stefan Möhlenkamp, Raimund Erbel, Karl-Heinz Jöckel on behalf of the Heinz Nixdorf Recall Study Investigative Group
Sleep-Disordered Breathing, Sleep Quality, and Mild Cognitive Impairment in the General Population
Abstract: There is increasing evidence that sleep disorders are associated with cognitive decline. We, therefore, examined the cross-sectional association of sleep-disordered breathing (SDB), sleep quality, and three types of sleep complaints (difficulties initiating sleep, difficulties maintaining sleep, and early morning awakening) with mild cognitive impairment (MCI) and its subtypes. A group of 1,793 participants (51% men; 63.8±7.5 years) of the population-based Heinz Nixdorf Recall study (total sample n=4,157) received a screening for SDB and self-report measures of sleep complaints. Group comparisons were used to compare performances among five cognitive subtests. Multivariate logistic regression models were calculated to determine the association of MCI (n=230) and MCI subtypes (amnestic MCI, n=120); non-amnestic MCI, n=110) with SDB severity levels, poor sleep quality, and sleep complaints. Severe SDB (apnea-hypopnea index ≥30/h, n=143) was not associated with MCI, amnestic MCI, or non-amnestic MCI. Poor sleep quality was associated with MCI (Odds ratio (OR) =1.40, 95% confidence interval (CI) =1.02-2.03; fully adjusted) as well as frequently reported difficulties initiating sleep (OR=1.94, 1.20-3.14), difficulties maintaining sleep (OR=2.23, 1.27-4.63), and early morning awakening (OR=2.30, 1.32-4.00). Severe difficulties initiating sleep (OR=2.23, 1.21-4.13) and early morning awakening (OR=2.88, 1.45-5.73) were solely associated with the amnestic MCI subtype, whereas severe difficulties maintaining sleep (OR=3.84, 1.13-13.08) was associated with non-amnestic MCI. Our results suggest that poor sleep quality, rather than SDB, is associated with MCI. The selective association of difficulties initiating sleep and early morning awakening with amnestic MCI and of difficulties maintaining sleep with non-amnestic MCI might serve as a marker to improve diagnostic accuracy in the earliest stages of cognitive impairment and will be further investigated in our longitudinal examination.
Pages 499-513
Haijun Shao*, Yiying Zhang*, Yuanlin Dong, Buwei Yu, Weiming Xia, Zhongcong Xie (Handling Associate Editor: Xuemin Xu) *These authors contributed equally to the work.
Chronic Treatment with Anesthetic Propofol Improves Cognitive Function and Attenuates Caspase Activation in Both Aged and Alzheimer’s Disease Transgenic Mice
Abstract: There is a need to seek new treatment(s) for Alzheimer’s disease (AD). A recent study showed that AD patients may have decreased levels of functional GABA receptors. Propofol, a commonly used anesthetic, is a GABA receptor agonist. We therefore set out to perform a proof of concept study to determine whether chronic treatment with propofol (50 mg/kg/week) can improve cognitive function in both aged wild-type (WT) and AD transgenic (Tg) mice. Propofol was administrated to the WT and AD Tg mice once a week for 8 or 12 weeks, respectively. Morris water maze was used to assess the cognitive function of the mice following the propofol treatment. Activation of caspase-3, caspase-9, and caspase-8 was investigated using western blot analysis at the end of the propofol treatment. In the mechanistic studies, effects of propofol, amyloid-β protein (Aβ), and GABA receptor antagonist flumazenil on caspase-3 activation and opening of the mitochondrial permeability transition pore were assessed in H4 human neuroglioma and mouse neuroblastoma cells by western blot analysis and flow cytometry. Here we showed that the propofol treatment improved cognitive function and attenuated brain caspase-3 and caspase-9 activation in both aged WT and AD Tg mice. Propofol attenuated Aβ-induced caspase-3 activation and opening of the mitochondrial permeability transition pore in the cells, and flumazenil inhibited the propofol’s effects. These results suggested that propofol might improve cognitive function via attenuating the Aβ-induced mitochondria dysfunction and caspase activation, which explored the potential that anesthetic propofol could improve cognitive function in elderly and AD patients.
Pages 515-523
Mariam Torkamani, Louise McDonald, Ignasi Saez Aguayo, Christos Kanios, Maria-Nefeli Katsanou, Laura Madeley, Patricia D. Limousin, Andrew J. Lees, Maria Haritou, Marjan Jahanshahi and the ALADDIN Collaborative Group
A Randomized Controlled Pilot Study to Evaluate a Technology Platform for the Assisted Living of People with Dementia and their Carers
Abstract: The use of telemedicine is becoming increasingly popular in assisting with the home management of People with Dementia (PwD) by offering services to the carers that may enhance their ability to care for their relative for longer. A computerized platform, ALADDIN, was evaluated in its usefulness to reduce carer burden and distress and to improve their quality of life, in an attempt to delay institutionalization of PwD. ALADDIN offers educational material about dementia to carers and provides the opportunity to contact other carers and clinicians. ALADDIN also facilitates remote monitoring of the PwD and their carers by the clinicians to enable speedy delivery of appropriate intervention. The ALADDIN platform was piloted at three European sites, and used by thirty carers of PwD living in the community (platform group). The platform group and a control group of thirty PwD and their carers were assessed at baseline, 3 months, and 6 months. The results showed a significant improvement in the quality of life of the carers in the platform group, with some reduction in carer burden and distress. The platform was useful in monitoring the patients and facilitating contact with other professionals. Access to and use of the ALADDIN platform was rated positively by carers and clinicians. The ALADDIN platform’s usefulness and applicability for prolonging the home management of PwD are discussed.
Pages 525-533
Vineet Kumar Khemka, Debajit Bagchi, Kausik Bandyopadhyay, Aritri Bir, Mrittika Chattopadhyay, Atanu Biswas, Debasis Basu, Sasanka Chakrabarti (Handling Associate Editor: Othman Ghribi)
Altered Serum Levels of Adipokines and Insulin in Probable Alzheimer’s Disease
Abstract: Cerebral hypometabolism of glucose, weight loss, and decreased food intake are characteristic features of sporadic Alzheimer’s disease (AD). A systematic study on the serum levels of adipokines and insulin, the major hormones regulating energy metabolism, food intake, and body weight, in sporadic AD is necessary. The present study compares the serum levels of leptin, adiponectin, and insulin, measured by commercially available immuno-assay kits, between controls and sporadic AD subjects. The results show a conspicuous decrease in the level of leptin, a dramatic rise in the level of adiponectin, and also a statistically significant increase in insulin level, in the blood of AD subjects, with respect to controls. The changes in the serum levels of adiponectin and insulin in AD are positively correlated with the severity of dementia. Likewise, the serum level of leptin in AD subjects is negatively correlated with the degree of dementia. The changes in the levels of adipokines and insulin have implications in the amyloid pathology, neurodegeneration, and hypometabolism of glucose existing in the AD brain.
Pages 535-549
Nicholas F. Fitz, Emilie L. Castranio, Alexis Y. Carter, Ravindra Kodali, Iliya Lefterov, Radosveta Koldamova (Handling Associate Editor: Ottavio Arancio)
Improvement of Memory Deficits and Amyloid-β Clearance in Aged APP23 Mice Treated with a Combination of Anti-Amyloid-β Antibody and LXR Agonist
Abstract: Passive amyloid-β (Aβ) vaccination has shown significant effects on amyloid pathology in pre-depositing amyloid-β protein precursor (AβPP) mice but the results in older mice are inconsistent. A therapeutic effect of LXR and RXR agonists consisting of improved memory deficits and Aβ pathology has been demonstrated in different Alzheimer’s disease (AD) mouse models. Here, we report the effect of a combination of N-terminal Aβ antibody and synthetic LXR agonist T0901317 (T0) on AD-like phenotype of APP23 mice. To examine the therapeutic potential of this combination the treatment of mice started at 11 months of age, when amyloid phenotype in this model is fully developed, and continued for 50 days. We show that Aβ immunization with or without LXR agonist restored the performance of APP23 transgenic mice in two behavior paradigms without affecting the existing amyloid plaques. Importantly, we did not observe an increase of brain microhemorrhage which is considered a significant side effect of Aβ vaccination. Target engagement was confirmed by increased Abca1 and ApoE protein level as well as increased ApoE lipidation in soluble brain extract. In interstitial fluid obtained by microdialysis, we demonstrate that immunization and T0 significantly reduced Aβ levels, indicating an increased Aβ clearance. We found no interaction between the immunotherapy and T0, suggesting no synergism, at least with these doses. The results of our study demonstrate that anti-Aβ treatments can ameliorate cognitive deficits in AβPP mice with advanced AD-like phenotype in conjunction with a decrease of Aβ in brain interstitium and increase of ApoE lipidation without affecting the existing amyloid plaques.
Pages 551-560
Shafaat Hussain, Shiva Mansouri, Åke Sjöholm, Cesare Patrone, Vladimer Darsalia
Evidence for Cortical Neuronal Loss in Male Type 2 Diabetic Goto-Kakizaki Rats
Abstract: Type 2 diabetes (T2D) is strongly associated with early cognitive decline and may facilitate the development of neurodegenerative diseases. Despite the overwhelming amount of indirect evidence pointing toward the presence of cerebral neurodegeneration in T2D, no hard proof of it on histological and quantitative levels exists. This warrants more research to investigate whether T2D can lead to neurodegeneration in the central nervous system and to study the precise nature and temporal dynamics of such changes. We performed a comprehensive quantitative assessment of T2D-induced changes in neuronal and glial numbers in the cerebral cortex using stereological methods. We compared the cellular composition of 3- and 13-month-old male type 2 diabetic Goto-Kakizaki (GK) rat brains. Age and sex-matched Wistar rats served as healthy controls. Our results show a significant decrease in neuron numbers (≈11%) in the cerebral cortex of 13-month-old GK rats compared to young, or Wistar rats, while astroglia numbers were unchanged. We also recorded increased microglia activation in aged diabetic rat brains as indicated by significantly increased average microglia cell volume. Our observations provide quantitative evidence of T2D-induced changes in brain’s cellular composition during aging. These findings may facilitate the mechanistic understanding of cognitive dysfunction and other neurodegenerative disorders in T2D.
Pages 561-574
Orkid Coskuner*, Ian V.J. Murray* (Handling Associate Editor: Debomoy Lahiri) *These authors contributed equally to the manuscript.
Adenosine Triphosphate (ATP) Reduces Amyloid-β Protein Misfolding in vitro
Abstract: Alzheimer’s disease (AD) is a devastating disease of aging that initiates decades prior to clinical manifestation and represents an impending epidemic. Two early features of AD are metabolic dysfunction and changes in amyloid-β protein (Aβ) levels. Since levels of ATP decrease over the course of the disease and Aβ is an early biomarker of AD, we sought to uncover novel linkages between the two. First and remarkably, a GxxxG motif is common between both Aβ (oligomerization motif) and nucleotide binding proteins (Rossmann fold). Second, ATP was demonstrated to protect against Aβ mediated cytotoxicity. Last, there is structural similarity between ATP and amyloid binding/inhibitory compounds such as ThioT, melatonin, and indoles. Thus, we investigated whether ATP alters misfolding of the pathologically relevant Aβ42. To test this hypothesis, we performed computational and biochemical studies. Our computational studies demonstrate that ATP interacts strongly with Tyr10 and Ser26 of Aβ fibrils in solution. Experimentally, both ATP and ADP reduced Aβ misfolding at physiological intracellular concentrations, with thresholds at ~500 µM and 1 mM respectively. This inhibition of Aβ misfolding is specific; requiring Tyr10 of Aβ and is enhanced by magnesium. Last, cerebrospinal fluid ATP levels are in the nanomolar range and decreased with AD pathology. This initial and novel finding regarding the ATP interaction with Aβ and reduction of Aβ misfolding has potential significance to the AD field. It provides an underlying mechanism for published links between metabolic dysfunction and AD. It also suggests a potential role of ATP in AD pathology, as the occurrence of misfolded extracellular Aβ mirrors lowered extracellular ATP levels. Last, the findings suggest that Aβ conformation may be a sensor of metabolic dysfunction.
Pages 575-585
Cristian E. Leyton, Sharon Savage, Muireann Irish, Samantha Schubert, Olivier Piguet, Kirrie J. Ballard, John R. Hodges
Verbal Repetition in Primary Progressive Aphasia and Alzheimer’s Disease
Abstract: We aimed to explore the nature of verbal repetition deficits and infer the cognitive systems involved in primary progressive aphasia (PPA) and Alzheimer’s disease (AD). A total of 63 patients (13 semantic variant (sv-PPA), 17 nonfluent/agrammatic variant (nfv-PPA), 10 logopenic variant (lv-PPA), 23 AD) and 13 matched healthy controls completed a battery of tests that included naming, word comprehension, digit span, repetition of multisyllabic single words, monosyllabic word span presented under similar and dissimilar phonological conditions, and sentence repetition. All patient groups displayed some level of impairment, however, specific patterns emerged in each variant. Participants with sv-PPA were the least impaired, showing marginal difficulties exclusively for sentence repetition, whereas those with lv-PPA had the worst overall performance. Cases with nfv-PPA showed compromised repetition of multisyllabic and phonologically similar words. The deficit in cases with AD was confined to span tasks. These distinctive patterns of language impairments can assist in the differential diagnosis of PPA variants and point toward the vulnerability of specific cognitive systems in each syndrome.
Pages 587-597
Xuemei Feng*, Zhouxian Bai*, Jiajia Wang*, Bin Xie, Jiya Sun, Guangchun Han, Fuhai Song, Peter J. Crack, Yong Duan, Hongxing Lei *These authors contributed equally to this work.
Robust Gene Dysregulation in Alzheimer’s Disease Brains
Abstract: The brain transcriptome of Alzheimer’s disease (AD) reflects the prevailing disease mechanism at the gene expression level. However, thousands of genes have been reported to be dysregulated in AD brains in existing studies, and the consistency or discrepancy among these studies has not been thoroughly examined. Toward this end, we conducted a comprehensive survey of the brain transcriptome datasets for AD and other neurological diseases. We first demonstrated that the frequency of observed dysregulation in AD was highly correlated with the reproducibility of the dysregulation. Based on this observation, we selected 100 genes with the highest frequency of dysregulation to illustrate the core perturbation in AD brains. The dysregulation of these genes was validated in several independent datasets for AD. We further identified 12 genes with strong correlation of gene expression with disease progression. The relevance of these genes to disease progression was also validated in an independent dataset. Interestingly, we found a transcriptional “cushion” for these 100 genes in the less vulnerable visual cortex region, which may be a critical component of the protection mechanism for less vulnerable brain regions. To facilitate the research in this field, we have provided the expression information of ~8000 relevant genes on a publicly accessible web server AlzBIG (http://alz.big.ac.cn).
Pages 599-613
Minho Moon*, Jin Gyu Choi*, Sun Yeou Kim, Myung Sook Oh *These authors contributed equally to this study.
Bombycis excrementum Reduces Amyloid-β Oligomer-Induced Memory Impairments, Neurodegeneration, and Neuroinflammation in Mice
Abstract: Alzheimer’s disease (AD) is the most common cause of progressive dementia and is characterized by memory impairments, neuronal death, and neuroinflammation. AD-related pathophysiology is caused primarily by the presence of amyloid-β oligomers (AβO). Recently, an increased focus has been directed toward natural compounds or medicinal extracts for the treatment of AD. Extracts from Bombycis excrementum (BE), which is composed of various bioactive constituents and mulberry leaves (the preferred food of silkworms), have been shown to possess anti-inflammatory, anti-diabetic, and anti-oxidative effects. Additionally, mulberry leaves exert anti-amyloidogenic action and neuroprotective effects against Aβ peptides but it is unknown whether BE has a therapeutic effect on AD-related pathologies. Therefore, the present study examined whether BE inhibits AβO-induced memory loss, neuronal death, and inflammation. Behavioral tests revealed that BE significantly ameliorated AβO-induced memory impairments and inhibited AβO-induced neuronal loss in cultured cells and the brains of mice. BE also significantly inhibited microgliosis and astrogliosis following intra-hippocampal AβO injections in mice. Furthermore, BE significantly attenuated the release of nitric oxide from microglia and reduced AβO-induced S100-β cytokine release from activated astrocytes. These results suggest that BE may be a candidate agent for the treatment of AD.
Pages 615-631
Chen-Chen Tan, Jin-Tai Yu, Hui-Fu Wang, Meng-Shan Tan, Xiang-Fei Meng, Chong Wang, Teng Jiang, Xi-Chen Zhu, Lan Tan (Handling Associate Editor: Francesco Panza)
Efficacy and Safety of Donepezil, Galantamine, Rivastigmine, and Memantine for the Treatment of Alzheimer’s Disease: A Systematic Review and Meta-Analysis
Abstract: Background: The role of currently available drugs for Alzheimer’s disease (AD) has been controversial, with some national formularies restricting their use, and health economists questioning whether the small clinical effects are economically worthwhile. Objective: To estimate the efficacy and safety of donepezil, galantamine, rivastigmine, and memantine for the treatment of AD. Methods: Double-blind, placebo-controlled, with random assignment to a cholinesterase inhibitor or memantine trials were included into the pooled studies. Results: Cognitive effects were significant for all drugs, ranging from a -1.29 points mean difference (95% CI -2.30 to -0.28) in the 20 mg daily memantine trials to -3.20 points (95% CI -3.28 to -3.12) in the 32 mg daily galantamine group. Only memantine had no effect on the Clinicians’ Global Impression of Change scale. No behavioral benefits were observed, except for -2.72 (95% CI -4.92 to -0.52) in the 10 mg daily donepezil group and -1.72 (95% CI -3.12 to -0.33) for 24 mg daily galantamine trial. Only 5 mg daily donepezil had no effect on the function outcome. Compared with placebo, more dropouts and adverse events occurred with the cholinesterase inhibitors, but not with memantine. Conclusions: Cholinesterase inhibitors and memantine are able to stabilize or slow decline in cognition, function, behavior, and global change.
Pages 633-640
Pietro Gareri, Daria Putignano, Alberto Castagna, Antonino Maria Cotroneo, Grazia De Palo, Andrea Fabbo, Luigi Forgione, Attilio Giacummo, Roberto Lacava, Saverio Marino, Maurizio Simone, Amedeo Zurlo, Salvatore Putignano
Retrospective Study on the Benefits of Combined Memantine and cholinEsterase inhibitor treatMent in AGEd Patients affected with Alzheimer’s Disease: The MEMAGE Study
Abstract: Background. Combined therapy of memantine and acetylcholinesterase inhibitors (AChEIs) in patients with Alzheimer’s disease (AD) may be associated with higher benefits than either monotherapy. Objective. This retrospective multicentric study conducted in seven Italian Ambulatory Centers for Dementia assessed the efficacy and safety of memantine 20 mg/day administered for 6 months in addition to an AChEI in AD patients with worsened cognitive functions and behavioral disorders. Methods. A total number of 240 patients (61.7% of women, 38.3% men, mean age 77.9 ± 7.32 years old) who had started treatment with the combination therapy were recruited. At baseline (T0), Month 3 (T1), and Month 6 (T2), cognitive functions were assessed by Mini-Mental State Examination (MMSE), functional dependence by activities of daily living (ADL) and instrumental ADL, behavioral disturbances by the Neuropsychiatric Inventory (NPI), and comorbidities by Cumulative Illness Rating Scale. Adverse events were reported during the study. Results. MMSE total score significantly increased at Month 6 (p=0.029 versus month 3) and IADL total score significantly decreased from baseline to endpoint (p=0.033). There were no significant changes from baseline in mean ADL, despite significant improvements in NPI total score. The mean MMSE total score significantly increased with the combination donepezil + memantine compared to rivastigmine + memantine. The adverse events profile was in line with the expected range of the drugs studied and concomitant therapies. Overall, 17 patients discontinued treatment in the observation time. Conclusion. Combined treatment with memantine and AChEIs was effective in patients with AD, particularly in slowing cognitive impairment and preventing the onset of agitation and aggression in elderly AD patients.
Pages 641-642
Commentary
Francesco Mattace-Raso
Is Memantine+Acetylcholinesterase Inhibitor Treatment Superior to Either Therapy Alone in Alzheimer’s Disease?
Abstract: Alzheimer’s disease is the most common form of dementia in the elderly. Currently, there is no established standard treatment for this disease; therefore, the treatment of Alzheimer’s disease will be a major challenge for physicians in the next decade in order to ameliorate quality of life of patients and reduce the costs for the communities.
Pages 643-650
Jun Wang*, Merina Varghese*, Kenjiro Ono, Masahito Yamada, Samara Levine, Nikos Tzavaras, Bing Gong, William J. Hurst, Robert D. Blitzer, Giulio Maria Pasinetti *These authors contributed equally to this work.
Cocoa Extracts Reduce Oligomerization of Amyloid-β: Implications for Cognitive Improvement in Alzheimer’s Disease
Abstract: Background: Alzheimer’s disease (AD) is the most common age-related neurodegenerative disorder, characterized by pathological aggregates of amyloid peptide-β (Aβ) and tau protein. Currently available therapies mediate AD symptoms without modifying disease progression. Polyphenol-rich diets are reported to reduce the risk for AD. Objective: In the present study, we investigated the AD disease-modifying effects of cocoa, a rich source of flavanols, which are a class of polyphenols. We hypothesized that cocoa extracts interfere with amyloid-β oligomerization to prevent synaptic deficits. Methods: We tested the effects of three different cocoa extracts, viz. Natural, Dutched, and Lavado extracts, on Aβ42 and Aβ40 oligomerization, using photo-induced cross-linking of unmodified proteins technique. To assess the effects of cocoa extracts on synaptic function, we measured long term potentiation in mouse brain hippocampal slices exposed to oligomeric Aβ. Results: Our results indicate that cocoa extracts are effective in preventing the oligomerization of Aβ, with Lavado extract being most effective. Lavado extract, but not Dutched extract, was effective in restoring the long term potentiation response reduced by oligomeric Aβ. Conclusion: Our findings indicate that cocoa extracts have multiple disease-modifying properties in AD and present a promising route of therapeutic and/or preventative initiatives.
