22, Number 4, December 2010
Claudio Babiloni, Roberta Lizio, Fabrizio Vecchio , Giovanni B. Frisoni, Michela Pievani, Cristina Geroldi, Fracassi Claudia, Raffaele Ferri, Bartolo Lanuzza, Paolo M. Rossini
Reactivity of Cortical Alpha Rhythms to Eye Opening in Mild Cognitive Impairment and Alzheimer’s Disease: an EEG Study
Abstract: Cortical sources of resting eyes-closed alpha rhythms are typically abnormal in mild cognitive impairment (MCI) and Alzheimer’s disease (AD) subjects. Here we tested the hypothesis of a progressive impairment of cortical alpha reactivity to eye-opening across amnesic MCI and mild AD subjects, reflecting another aspect of the impairment of cortical neural synchronization. Resting electroencephalography (EEG) data were recorded in 36 normal elderly subjects (Nold), 91 amnesic MCI, and 31 mild AD subjects during eyes-closed and -open conditions. EEG sources were estimated by LORETA software. In the eye-closed condition, posterior alpha 1 (8-10.5 Hz) sources were lower in MCI and AD than Nold subjects. The opposite was true for occipital delta sources (2-4 Hz). Reactivity to the eyes-open condition showed posterior alpha 1 and alpha 2 (10.5-13 Hz) sources was high in the Nold, intermediate in the MCI, and low in the AD subjects. Furthermore, occipital alpha 1 reactivity across MCI and AD subjects was correlated to the cognitive impairment as revealed by Mini-Mental State Examination score. In conclusion, at least at group level, the continuum across amnesic MCI and mild AD status is related to an impaired reactivity of cortical neuronal synchronization to eyes opening at alpha rhythms.
Lluís Samaranch*, Sebastián Cervantes*, Ana Barabash, Alvaro Alonso, José Antonio Cabranes, Isabel Lamet, Inés Ancín, Elena Lorenzo, Pablo Martínez-Lage, Alberto Marcos, Jordi Clarimón, Daniel Alcolea, Alberto Lleó, Rafael Blesa, Teresa Gómez-Isla, Pau Pastor *These authors contributed equally to the manuscript. (Handling Associate Editor: Eliecer Coto)
MAPT H1 and APOE ε4 Effect on Transition from Mild Cognitive Impairment to Dementia
Abstract: Microtubule-associated protein tau (MAPT) and apolipoprotein E (APOE) are involved in the pathogenic mechanisms of Alzheimer’s disease (AD). We prospectively followed three longitudinal independent samples (total n=319) with amnestic mild cognitive impairment (MCI) and analyzed whether MAPT H1/H2 haplotypes and APOE ε4 polymorphisms accelerated the rate of progression from MCI to dementia. At the end of the study, 172 subjects remained cognitively stable, whereas 147 progressed to dementia. APOE ε4 and MAPT H1/H1 were independently associated with an increased rate of progression to dementia in the combined sample. Cox regression models of the combined MCI sample showed that MAPT H1/H1 carriers had an increased rate of progression to dementia compared with non carriers (Hazard Ratio=1.45; 95% CI=1.04-2.02; p=0.028) and time-to-progression was shortened by 1.37 years. APOE ε4 allele also accelerated progression to dementia (Hazard Ratio=1.47; 95% CI=1.06-2.04; p=0.020) and reduced the time-to-progression by 0.87 years. Additionally, MAPT H1/H1 genotype and APOE ε4 allele had an additive effect in progression to dementia, increasing progression rate to dementia (Hazard Ratio=2.24, 95% CI=1.40-3.58; p=0.001) and shortening time-to-progression to dementia by 2.92 years. Similar results were obtained when only considering progression to AD-type dementia. Our results suggest that both MAPT H1/H1 genotype and APOE ε4 allele could lead to a more rapid progression to dementia among MCI subjects, probably obeying an increased rate of amyloid-β and tau brain deposition.
Supplementary Data for Samaranch et al. article (PDF)
Sandra D. Mulder, C. Erik Hack, Wiesje M van der Flier, Philip Scheltens, Marinus A. Blankenstein, Robert Veerhuis (Handling Associate Editor: Piotr Lewczuk)
Evaluation of Intrathecal Serum Amyloid P (SAP) and C-Reactive Protein (CRP) Synthesis in Alzheimer’s Disease with the Use of Index Values
Abstract: Serum amyloid P (SAP) and C-reactive protein (CRP) are proteins involved in innate immunity. The expression of SAP and CRP is increased in Alzheimer’s disease (AD) brain tissue, compared to healthy controls. Although both proteins are found in cerebrospinal fluid (CSF), their origin is unclear. We investigated if increased local production of SAP and CRP in AD brain results in higher levels in CSF with the use of index values. To study this, SAP, CRP, and albumin levels were determined in CSF and serum samples of 30 control (65 ± 11 years; 57% female) and 140 AD subjects (65 ± 9 years; 53% female). To correct for inter-individual differences in protein diffusion from blood to CSF, quotients (Q=CSF/serum) of SAP, CRP, and albumin and index values (Qprotein/Qalb) were calculated. The results showed no significant differences in SAP and CRP index values between control and AD subjects, although eight percent of individual AD patients showed evidence of intrathecal SAP or CRP production using the Reiber hyperbolic model. Interestingly, the SAP index value was much lower than expected, based on its molecular size. In conclusion, these data suggest that local production of SAP and CRP in the AD brain does not substantially contribute to the CSF levels.
Alex Bahar-Fuchs, Gael Chételat, Victor L. Villemagne, Simon Moss, Kerryn Pike, Colin L. Masters, Christopher Rowe, Greg Savage
Olfactory Deficits and Amyloid-β Burden in Alzheimer’s Disease, Mild Cognitive Impairment, and Healthy Aging: A PiB PET Study
Abstract: Olfactory deficits and increased amyloid-β (Aβ) burden are observed in people with amnestic mild cognitive impairment (aMCI); both factors may be predictive of Alzheimer’s disease (AD). We explored whether olfactory identification is related to in vivo measures of Aβ burden using Pittsburgh Compound B (PiB) PET. Nineteen control, 24 aMCI, and 20 AD participants completed an olfactory identification task and underwent PiB PET scanning. Control participants performed better on olfactory identification and showed lower PiB binding than aMCI patients. There was a significant correlation between both factors when pooling all groups together but not when considering each group separately. In addition, the olfactory identification score did not differ between aMCI participants who were PiB-positive and those who were PiB-negative. We conclude that AD-related olfactory identification deficits are not directly related to Aβ burden.
Teemu Paajanen, Tuomo Hänninen, Catherine Tunnard, Patrizia Mecocci, Tomasz Sobow, Magda Tsolaki, Bruno Vellas, Simon Lovestone, Hilkka Soininen, for the AddNeuroMed Consortium
CERAD Neuropsychological Battery Total Score in Multinational Mild Cognitive Impairment and Control Populations: The AddNeuroMed Study
Abstract: An important focus in Alzheimer’s disease (AD) research is the development of methods for early diagnosis. Despite progress with some other biomarkers, sensitive and specific neuropsychological measures for identifying subjects in the prodromal phase of AD remain the most promising early diagnostic tool. We evaluated the value of the composite score for the Consortium to Establish a Registry for Alzheimer’s disease Neuropsychological Battery (CERAD-NB) in Europeans with mild cognitive impairment (MCI) and in control populations. Baseline clinical data were analyzed from 223 healthy elderly and 224 subjects with MCI from the prospective AddNeuroMed study carried out in Finland, France, Greece, Italy, Poland, and the United Kingdom. The total score for CERAD-NB was calculated by the subtest addition method. The CERAD total score, adjusted for age, gender, education, and country, clearly differentiated the control and MCI groups (p<0.001). The optimal between-groups cut-off point for the CERAD total score derived from ROC analysis yielded 81.5% sensitivity and 75.4% specificity (AUC=0.848, p<0.001). The CERAD total score was superior to the Mini-Mental Status Examination, or any single CERAD subtest in discriminating between the control and MCI groups. While the overall level of the CERAD total score varied between the different countries, it remained accurate in differentiating controls and MCI subjects within each country. We conclude that the CERAD total score is an accurate measure for detecting mild cognitive impairment, but implementing specific cut-off points needs to be based upon country specific normative data.
Madhav Thambisetty*, Romina Tripaldi*, Joanna Riddoch-Contreras*, Abdul Hye, Yang An, James Campbell, Jitka Sojkova, Anna Kinsey, Steven Lynham, Yun Zhou, Luigi Ferrucci, Dean F. Wong, Simon Lovestone**, Susan M. Resnick** (*, ** These authors contributed equally to the manuscript)
Proteome-Based Plasma Markers of Brain Amyloid-β Deposition in Non-Demented Older Individuals
Abstract: Blood-based markers reflecting core pathological features of Alzheimer’s disease (AD) in pre-symptomatic individuals are likely to accelerate the development of disease-modifying treatments. Our aim was to discover plasma proteins associated with brain amyloid-β (Aβ) burden in non-demented older individuals. We performed discovery-phase experiments using two dimensional gel electrophoresis (2DGE) and mass spectrometry-based proteomic analysis of plasma in combination with 11C-PiB PET imaging of the brain in samples collected 10 years prior to the PET scans. Confirmatory studies used ELISA assays in a separate set of blood samples obtained within a year of the PET scans. We observed that a panel of 18 2DGE plasma protein spots effectively discriminated between individuals with high and low brain Aβ. Mass spectrometry identified these proteins, many of which have established roles in Aβ clearance, including a strong signal from apolipoprotein-E (ApoE). In validation-phase studies, we observed a strong association between plasma ApoE concentration and Aβ burden in the medial temporal lobe. Targeted voxel-based analysis localized this association to the hippocampus and entorhinal cortex. APOE ε4 carriers also showed greater Aβ levels in several brain regions relative to ε4 non-carriers. These results suggest that both peripheral concentration of ApoE protein and APOE genotype are related to early neuropathological changes in brain regions vulnerable to AD pathology even in the non-demented elderly. Our strategy combining proteomics with in vivo brain amyloid imaging holds promise for the discovery of biologically relevant peripheral markers in those at risk for AD.
David T. R. Coulson, Nancy Beyer, Joe G. Quinn, Simon Brockbank, Jan Hellemans, G. Brent Irvine, Rivka Ravid, Janet A. Johnston (Handling Associate Editor: Craig Atwood)
BACE1 mRNA Expression in Alzheimer’s Disease Postmortem Brain Tissue
Abstract: β-site AβPP cleaving enzyme 1 (BACE1) catalyses the rate-limiting step for production of amyloid-β (Aβ) peptides, involved in the pathological cascade underlying Alzheimer’s disease (AD). Elevated BACE1 protein levels and activity have been reported in AD postmortem brains. Our study explored whether this was due to elevated BACE1 mRNA expression. RNA was prepared from five brain regions in three study groups: controls, individuals with AD, and another neurodegenerative disease group affected by either Parkinson’s disease (PD) or dementia with Lewy bodies (DLB). BACE1 mRNA levels were measured using quantitative realtime PCR (qPCR) and analyzed by qbasePLUS using validated stably-expressed reference genes. Expression of glial and neuronal markers (glial fibrillary acidic protein (GFAP) and neuron-specific enolase (NSE), respectively) were also analyzed to quantify the changing activities of these cell populations in the tissue. BACE1 mRNA levels were significantly elevated in medial temporal and superior parietal gyri, compared to the PD/DLB and/or control groups. Superior frontal gryus BACE1 mRNA levels were significantly increased in the PD/DLB group, compared to AD and control groups. For the AD group, BACE1 mRNA changes were analyzed in the context of the reduced NSE mRNA, and strongly increased GFAP mRNA levels apparent as AD progressed (indicated by Braak stage). This analysis suggested that increased BACE1 mRNA expression in remaining neuronal cells may contribute to the increased BACE1 protein levels and activity found in brain regions affected by AD.
Tomasz Gabryelewicz*, Mario Masellis*, Mariusz Berdynski*, Juan M. Bilbao, Ekaterina Rogaeva, Peter St. George-Hyslop, Anna Barczak, Krzysztof Czyzewski, Maria Barcikowska, Zbigniew Wszolek, Sandra E. Black&, Cezary Zekanowski& (*These authors have contributed equally to the work described in the article. &These authors have contributed equally as senior authors.)
Intra-Familial Clinical Heterogeneity due to FTLD-U with TDP-43 Proteinopathy Caused by a Novel Deletion in Progranulin Gene (PGRN)
Abstract: Frontotemporal dementia (FTD) is one of the commonest forms of early-onset dementia, accounting for up to 20% of all dementia patients. Recently, it has been shown that mutations in progranulin gene (PGRN) cause many familial cases of FTD. Members of a family affected by FTD spectrum disorders were ascertained in Poland and Canada. Clinical, radiological, molecular, genetic, and pathological studies were performed. A sequencing analysis of PGRN exons 1-13 was performed in the proband. Genotyping of the identified PGRN mutation and pathological analysis was carried out in the proband’s brother. The onset of symptoms of FTD in the proband included bradykinesia, apathy, and somnolence followed by changes in personality, cognitive deficits, and psychotic features. The proband’s clinical diagnosis was FTD and parkinsonism (FTDP). DNA sequence analysis of PGRN revealed a novel, heterozygous mutation in exon 11 (g.2988_2989delCA, P439_R440fsX6). The mutation introduced a premature stop codon at position 444. The proband’s brother with the same mutation had a different course first presenting as progressive non-fluent aphasia, and later evolving symptoms of behavioral variant of FTD. He also developed parkinsonism late in the disease course evolving into corticobasal syndrome. Pathological analysis in the brother revealed Frontotemporal Lobar Degeneration-Ubiquitin (FTLD-U)/TDP-43 positive pathology. The novel PGRN mutation is a disease-causing mutation and is associated with substantial intra-familial clinical heterogeneity. Although presenting features were different, rapid and substantial deterioration in the disease course was observed in both family members.
Mathieu P. Lichtenstein*, Paulina Carriba*, María Antonia Baltrons, Beata Wojciak-Stothard, Jeffrey R. Peterson, Agustina García#, Elena Galea# (*,#Equal author contribution)
Secretase-Independent and RhoGTPase/PAK/ERK-Dependent Regulation of Cytoskeleton Dynamics in Astrocytes by NSAIDs and Derivatives
Abstract: Profens like ibuprofen, R-flurbiprofen, or CHF5074 are being considered for the treatment of Alzheimer’s disease because epidemiological data indicates that non-steroidal anti-inflammatory drugs protective against neurodegeneration. Rho-GTPases are small G proteins, including RhoA, Cdc42, and Rac1, which control cytoskeleton dynamics. Because ibuprofen promotes axon growth via RhoA in neurons, we examined whether profens modulate astrocyte plasticity via Rho-GTPases. We report that ibuprofen (100-500 µM), R-flurbiprofen (100-500 µM), and CHF5074 (10-30 µM) caused a concentration-dependent stellation of astrocytes in primary cultures, associated with the reorganization of GFAP and actin filaments. The stellation was independent of COX2, α-, β- or γ-secretase as judged by the lack of effect of inhibitors of these enzymes. RhoA, PAK, and Cdc42, but not Rac1, accounted for the profen-mediated stellation, as concluded from the joint analyses of activities and reversal experiments with adenoviral or pharmacological manipulations. Ibuprofen accelerated migration in a scratch-wound assay, while R-flurbiprofen had no effect and CHF5074 caused deceleration. Cell polarity regulation by Cdc42 and ERK1/2 may underlie the paradoxical effects of profens on migration. We conclude that profens regulate cytoskeleton dynamics in astrocytes via Rho-GTPases, PAK, and ERK1/2. Since migration is a hallmark of astrocyte response during inflammation we propose that, in addition to (or instead of) lowering amyloid-β42 via secretases, ibuprofen and its derivatives may prevent AD by modulating astrocyte reactivity through Rho-GTPase/PAK/ERK-dependent signaling.
Supplementary Data for Lichtenstein et al. article (PDF)
Josep Garre-Olmo, Secundino López-Pousa, Joan Vilalta-Franch, Manuel de Gracia Blanco, Antoni Bulbena Vilarassa
Grouping and Trajectories of the Neuropsychiatric Symptoms in Patients with Alzheimer’s Disease, Part I: Symptom Clusters
Abstract: The behavioral and psychological symptoms of dementia (BPSD) are frequently observed in Alzheimer’s disease (AD) and affect more than 80% of patients over the course of AD. The objective of this study was to establish a model for grouping the symptoms of BPSD into clinical syndromes. Over a 24-month period, an observational study was conducted using a population of ambulatory patients with AD of mild to moderate severity. The Neuropsychiatric Inventory (NPI) was administered to the patients’ caregivers every 6 months. BPSD were grouped using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) of the NPI scores of each assessment. The sample population consisted of 491 patsients (70.9% women) with an average age of 75.2 years (SD=6.6). The five EFA suggested that there was a stable three-factor structure. According to the results of the EFA, three models of symptom grouping were adjusted using CFA methodology. The CFA model that satisfactorily grouped the NPI scores into three factors included a psychotic syndrome (hallucinations, delusions), an affective syndrome (depression, anxiety, irritability, agitation) and a behavior syndrome (euphoria, disinhibition, apathy, aberrant motor behavior). Based on our findings, we propose a model for grouping the BDSD in which there are core nuclear syndromes (psychotic and affective) as well an unspecified behavior syndrome constituted by satellite symptoms that may be related to the presence of the nuclear syndromes.
Josep Garre-Olmo, Secundino López-Pousa, Joan Vilalta-Franch, Manuel de Gracia Blanco, Antoni Bulbena Vilarassa
Grouping and Trajectories of Neuropsychiatric Symptoms in Patients with Alzheimer’s Disease. Part II: Two-Year Patient Trajectories
Abstract: The behavioral and psychological symptoms of dementia (BPSD) are characterized by fluctuations in their frequency and severity as well as by differences in the concurrent presentation of different symptoms. The goal of the current study was to identify groups of patients with Alzheimer’s disease (AD) that had similar trajectories in the expression of BPSD. Over a 24-month period, an observational study was conducted using a population of ambulatory patients with AD of mild or moderate severity. The Neuropsychiatric Inventory (NPI) was administered every 6 months to the patient’s caregiver. In order to classify patients according to changes in the frequency and severity of BPSD, growth mixture models were fitted to the applied to the grouping of NPI subscales in the following three categories: psychotic syndrome (hallucinations and delusions), affective syndrome (depression, anxiety, irritability, and agitation), and behavioral syndrome (disinhibition, euphoria, apathy, and aberrant motor behavior). The sample population consisted of 491 patients (70.9% women) that had an average age of 75.2 years (SD=6.6). Different trajectory patterns were identified based on differences in changes over the time in the frequency (stable, increasing, decreasing, or fluctuating in course) and severity (low, moderate, or elevated severity) for psychotic syndrome, emotional syndrome, and behavior syndrome. Patients with AD display a high degree of variability in the evolutionary course of BPSD. It is possible to identify groups of patients with similar evolutionary trajectories in terms of changes in the frequency and severity of BPSD.
Ana Martínez-García, Isabel Sastre, María Recuero, Jesús Aldudo, Elisabet Vilella, Ignacio Mateo, Pascual Sánchez-Juan, Teo Vargas, Eva Carro, Félix Bermejo-Pareja, Eloy Rodríguez-Rodríguez, Onofre Combarros, Marcel Rosich‑Estrago, Ana Frank, Fernando Valdivieso, María J. Bullido
PLA2G3, a Gene Involved in Oxidative Stress Induced Death, is Associated with Alzheimer’s Disease
Abstract: Oxidative stress, which plays a critical role in the pathogenesis of neurodegenerative diseases such as Alzheimer’s disease (AD), is intimately linked to aging, the best established risk factor for AD. Studies in neuronal cells subjected to oxidative stress, mimicking such stress in AD brains, are therefore of great interest. PLA2G3 is the most overexpressed gene in a human neuronal model of oxidative stress induced by the free radical-generating xanthine/xanthine oxidase (X-XOD) system, which provokes apoptotic cell death. In this work, we describe that PLA2G3 gene silencing produced a marked inhibition of X-XOD induced cell death, and that PLA2G3 polymorphisms are associated with AD in a Spanish case‑control sample. The capacity to respond to oxidative stress may therefore modulate the risk of AD, and PLA2G3 is a potential target to regulate neuronal damage induced by free radicals.
Yan-Ying Liu, Jin-Song Bian
Hydrogen Sulfide Protects Amyloid-β Induced Cell Toxicity in Microglia
Abstract: Alzheimer's disease (AD) is pathologically characterized by the accumulation of senile plaques, containing the activated microglia and amyloid-β peptides (Aβ). We found in the present study that aggregated Aβ1–40 peptide (25 µM, 24 h) significantly decreased viability of BV-2 microglial cells. This was concentration-dependently attenuated by NaHS (a hydrogen sulfide (H2S) donor, 25-500 µM). NaHS also significantly attenuated Aβ-induced LDH release and the up-regulation of protein expression of growth arrest DNA damage (GADD 153). These data suggest that H2S may attenuate Aβ-induced cell toxicity and cell cycle re-entry. Pretreatment with NaHS also suppressed the release of nitric oxide and the upregulation of inducible nitric oxide synthase. These effects were attenuated by exogenous application of NaHS or stimulation of endogenous generation of H2S with S-adenosyl-L-methionine, a cystathionine β synthase activator. NaHS also decreased the releases of TNF-α and suppressed the up-regulation of protein expression of cyclooxygenase 2, which were mimicked by blockade of p38 and JNK-MAPK. In addition, Aβ induced obvious loss of mitochondrial member potential (DYm) and activation of p38-, JNK-, and ERK-MAPKs. Application of NaHS attenuated these effects but failed to affect the activation of ERK. In conclusion, we demonstrated for the first time that H2S may protect cell against Aβ-induced cell injury by inhibition of inflammation, promotion of cell growth and preservation of mitochondrial function in a p38- and JNK-MAPK dependent manner. Our results suggest that H2S may have potential therapeutic value for treatment of AD.
Bengt Winblad, Ezio Giacobini, Lutz Frölich, Lawrence T. Friedhoff, Gosse Bruinsma, Robert E. Becker, Nigel H. Greig
Phenserine Efficacy in Alzheimer’s Disease
Abstract: To gather preliminary evidence in Alzheimer’s disease (AD) for the efficacy of phenserine, a non-competitive acetylcholinesterase inhibitor that has independent modulatory effects on amyloid-β generation, a 12-week comparison of patients receiving phenserine (10 and 15 mg BID) or placebo was conducted under double-blind conditions. Patients who completed 12 weeks of the double-blind before others were continued in the double-blind to determine longer-term treatment effects. At 12 weeks, mean ADAS-cog (AD assessment scale-cognitive) changes from baseline were -2.5 and -1.9 for high-dose phenserine (n=83) and placebo (n=81) groups, respectively, a non-statistically significant improvement for the high-dose phenserine group relative to placebo. CIBIC+ (clinician's interview based impression of change + caregiver’s input) values for the high-dose and placebo groups were similar at 12 weeks. For patients who received more than 12 weeks of therapy, the ADAS-cog changes were -3.18 and -0.66 for the high-dose phenserine (n=52) and placebo (n=63) groups, respectively, a difference achieving statistical significance (p=0.0286). After 12 weeks, CIBIC+ values were 3.59 and 3.95 for the high-dose (n=54) and placebo (n=66) groups respectively (p=0.0568). These results from this short-term study are consistent with phenserine potentially benefiting mild to moderate Alzheimer’s disease symptomatically but do not address possible amyloid metabolic mediated effects on disease processes in AD.
Inês Milagre, Maria João Nunes, Miguel Moutinho, Isabel Rivera, Andrea Fuso, Sigfrido Scarpa, Maria João Gama, Elsa Rodrigues (Handling Associate Editor: Fabio Coppede)
Chromatin-Modifying Agents Increase Transcription of CYP46A1, a Key Player in Brain Cholesterol Elimination
Abstract: The major mechanism of brain cholesterol elimination is the conversion of cholesterol into 24S-hydroxycholesterol by CYP46A1, a neuron-specific cytochrome P450. Since increasing evidence suggests that upregulation of CYP46A1 may be relevant for the treatment of Alzheimer’s disease, we aim to identify the molecular mechanisms involved in CYP46A1 transcription. Our previous studies demonstrated the role of Sp transcription factors in basal expression and histone deacetylase (HDAC) inhibitor-dependent derepression of CYP46A1. Here, we show that the demethylating agent 5’-Aza-2’-deoxycytidine (DAC) is a CYP46A1 inducer and that pre-treatment with DAC causes a marked synergistic activation of CYP46A1 transcription by trichostatin A. Surprisingly, bisulfite sequencing analysis revealed that the CYP46A1 core promoter is completely unmethylated in both human brain and non-neuronal human tissues where CYP46A1 is not expressed. Therefore, we have investigated Sp expression levels by western blot and real-time PCR, and their binding patterns to the CYP46A1 promoter, by electrophoretic mobility shift assay and chromatin immunoprecipitation assays, after DAC treatment. Our results showed that DAC decreases not only Sp1 and Sp3 protein levels, but also the binding activity of Sp3 to the +1 region of the CYP46A1 locus. Concomitantly, HDAC1 and HDAC2 were also significantly dissociated from the promoter. In conclusion, DAC induces CYP46A1 gene expression, in a DNA methylation-independent mechanism, decreasing Sp3/HDAC binding to the proximal promoter. Furthermore, by affecting the expression of the Sp3 transcription factor in neuronal cells, DAC might affect not only brain cholesterol metabolism, but also the expression of many other neuronal genes.
Johan Sundelöf, Johan Sundström, Oskar Hansson, Maria Eriksdotter-Jönhagen, Vilmantas Giedraitis, Anders Larsson, Malin Degerman-Gunnarsson, Martin Ingelsson, Lennart Minthon, Kaj Blennow, Lena Kilander, Hans Basun, Lars Lannfelt
Higher Cathepsin B Levels in Plasma in Alzheimer’s Disease Compared to Healthy Controls
Abstract: Cathepsin B is suggested to be involved in amyloid-β (Aβ) processing and Alzheimer’s disease (AD). Studies of cathepsin B levels in plasma and cerebrospinal fluid (CSF) have not been previously performed. We examined cathepsin B levels in plasma and CSF samples in persons with AD, mild cognitive impairment (MCI), and healthy controls in order to test the hypothesis that cathepsin B levels can discriminate persons with AD or MCI from healthy controls. Cathepsin B, Cystatin C, Aβ1-40 and Aβ1-42, total tau, phosphorylated tau, and albumin levels in plasma and CSF were analyzed by ELISA (Cathepsin B) turbidimetry (cystatin C), xMAP Luminex technology (Aβ1-40 and Aβ1-42 and tau), and Cobas C501 analyzer (albumin) in persons with AD (n=101), MCI (n=84), and healthy control subjects (n=28). Plasma cathepsin B levels were higher in persons with AD compared to healthy controls, both in unadjusted models and in multivariable models adjusting for age, gender, APOE genotype, cystatin C, and albumin levels: Odds ratio (OR) for AD per 1 SD of plasma cathepsin B; 2.04, 95% confidence interval (CI); 1.01-4.14, p=0.05. There was no difference between diagnostic groups in cathepsin B levels in CSF: OR for AD per 1 SD of CSF cathepsin B; 0.93, 95% CI; 0.37- 2.30, p=0.87. Plasma cathepsin B levels were higher in persons with AD compared to healthy controls whereas there was no difference between diagnostic groups in cathepsin B levels in CSF. Further investigation of cathepsin B as a predictor of AD is warranted.
Mary C. Tierney, Rahim Moineddin, Ian McDowell
Prediction of All-Cause Dementia Using Neuropsychological Tests within 10 and 5 Years of Diagnosis in a Community-Based Sample
Abstract: While neuropsychological tests have been identified for the early prediction of Alzheimer’s disease, this has not been established for prediction of all-cause dementia. This would be helpful for clinicians concerned about the risk of progression to dementia in patients who may present with a variety of medical and neurological conditions. We wanted to determine whether neuropsychological tests could accurately predict incident dementia within 10 and five years of diagnosis in a community-based sample. The Canadian Study of Health and Aging was conducted in three waves over a 10-year period (1991-2002). We studied 1472 non-demented participants who completed neuropsychological testing in 1991 and received a diagnostic assessment for dementia in 2001 (n = 284). We also studied 1231 non-demented participants who completed neuropsychological testing in 1996 and received a diagnostic assessment in 2001 (n = 634). Diagnosticians were blinded to performance on the predictive tests. Age, education, and gender were included as covariates in all regression analysis. Ten-year prediction: 2 tests, Rey Auditory Verbal Learning Test (RAVLT) short delayed verbal recall and Wechsler Adult Intelligence Test Revised (WAIS-R) Digit Symbol), were significant predictors of dementia (sensitivity = 78%, specificity = 72%, positive likelihood ratio = 2.81). Five-year prediction: 4 tests, Wechsler Memory Scale Information, RAVLT short delayed verbal recall, animal fluency, and WAIS-R Digit Symbol, significantly predicted incident dementia (sensitivity = 75%, specificity = 74%, positive likelihood ratio = 2.90). Regression models were supported with bootstrapping estimates. Neuropsychological tests can accurately predict progression to all-cause dementia within 10 years of diagnosis in a large community-based sample of non-demented participants.
Sofia Tzimopoulou, Vincent J. Cunningham, Thomas E. Nichols, Graham Searle, Nick P. Bird, Prafull Mistry, Ian J. Dixon, William A. Hallett, Brandon Whitcher, Andrew P. Brown, Marina Zvartau-Hind, Narinder Lotay, Robert Y. K. Lai, Mary Castiglia, Barbara Jeter, Julian C. Matthews, Kewei Chen, Dan Bandy, Eric M. Reiman, Michael Gold, Eugenii A. Rabiner, Paul M. Matthews
A Multi-Center Randomized Proof-of-Concept Clinical Trial Applying [18F]FDG-PET for Evaluation of Metabolic Therapy with Rosiglitazone XR in Mild to Moderate Alzheimer’s Disease
Abstract: Here we report the first multi-center clinical trial in Alzheimer’s disease (AD) using fluorodeoxyglucose positron emission tomography ([18F]FDG-PET) measures of brain glucose metabolism as the primary outcome. We contrasted effects of 12 months treatment with the PPARγ agonist Rosiglitazone XR versus placebo in 80 mild to moderate AD patients. Secondary objectives included testing for reduction in the progression of brain atrophy and improvement in cognition. Active treatment was associated with a sustained but not statistically significant trend from the first month for higher mean values in K index i and CMR index glu, novel quantitative indices related to the combined forward rate constant for [18F]FDG uptake and to the rate of cerebral glucose utilization, respectively. However, neither these nor another analytical approach recently validated using data from the Alzheimer’s Disease Neuroimaging Initiative indicated that active treatment decreased the progression of decline in brain glucose metabolism. Rates of brain atrophy were similar between active and placebo groups and measures of cognition also did not suggest clear group differences. Our study demonstrates the feasibility of using [18F]FDG-PET as part of a multi-center therapeutics trial. It suggests that Rosiglitazone is associated with an early increase in whole brain glucose metabolism, but not with any biological or clinical evidence for slowing progression over a 1 year follow up in the symptomatic stages of AD.
Supplementary Data for Tzimopoulou et al. article (PDF)
Marina Borro*, Rosaria A. Cavallaro*, Giovanna Gentile, Vincenzina Nicolia, Andrea Fuso, Maurizio Simmaco, Sigfrido Scarpa *these authors equally contribute to this work
One-Carbon Metabolism Alteration Affects Brain Proteome Profile in a Mouse Model of Alzheimer’s Disease
Abstract: Late Onset Alzheimer’s Disease (LOAD) can be associated to high homocysteine level and alteration of one-carbon metabolism. We previously demonstrated in the TgCRND8 mice strain, over-expressing human amyloid-β protein precursor, that B vitamin deficiency causes alteration of one-carbon metabolism, together with unbalance of S-adenosylmethionine/S-adenosylhomocysteine levels, and is associated with AD like hallmarks as increased amyloid-β plaque deposition, hyperhomocysteinemia, and oxidative stress. The same model of nutritional deficit was used here to study the variation of the brain protein expression profile associated to B vitamin deficiency. A group of proteins mainly involved in neuronal plasticity and mitochondrial functions was identified as modulated by one-carbon metabolism. These findings are consistent with increasing data about the pivotal role of mitochondrial abnormalities in AD patho-physiology. The identified proteins might represent new potential biomarkers of LOAD to be further investigated.
Mira Didic, Jean-Philippe Ranjeva, Emmanuel Barbeau, Sylviane Confort-Gouny, Yann Le Fur, Olivier Felician, Julien Mancini, Michel Poncet, Mathieu Ceccaldi, Patrick Cozzone
Impaired Visual Recognition Memory in Amnestic Mild Cognitive Impairment is Associated with Mesiotemporal Metabolic Changes on Magnetic Resonance Spectroscopic Imaging
Abstract: In the early stages of Alzheimer’s disease (AD), neurofibrillary tangles develop in the mesial temporal lobe (MTL), first in the anterior subhippocampal (perirhinal/entorhinal) cortex and then in the hippocampal formation. The anterior subhippocampal region plays a key role in visual recognition memory (VRM). VRM has been reported to be impaired in amnestic mild cognitive impairment (aMCI)-patients. The aim of the present study was to determine if an impairment of VRM is associated with metabolic changes in the MTL using magnetic resonance spectroscopic imaging and if evaluating VRM can contribute to the early diagnosis of AD. 28 patients with aMCI and 28 controls underwent a full neuropsychological assessment including an evaluation of VRM. NAA/mIno ratios, reduced in patients with AD and associated with the severity of pathological changes, were determined in the MTL. aMCI-patients were further divided into two subgroups according to their VRM performance. aMCI-patients showed decreased NAA/mIno levels in the right hippocampus compared with controls. aMCI-patients with impaired VRM showed decreased NAA/mIno ratios in the MTL bilaterally, including a region that sampled the left anterior subhippocampal cortex, compared to controls. No changes were found in aMCI patients with normal VRM. Performance on the VRM task correlated with NAA/mIno levels in the anterior MTL. Clinical 6-year follow-up data (available for 78.6 % of the aMCI-patients) indicates that impaired VRM could predict conversion to AD with a sensitivity and specificity of 81.8 %. These findings provide further evidence that impaired VRM, as a hallmark of MTL dysfunction, may contribute to the early diagnosis of AD.
Davide Chiasserini*, Lucilla Parnetti*, Ulf Andreasson, Henrik Zetterberg, David Giannandrea, Paolo Calabresi, Kaj Blennow (Handling Associate Editor: Barbara Borroni) *Both authors contributed equally to this work.
CSF Levels of Heart Fatty Acid Binding Protein are Altered During Early Phases of Alzheimer’s Disease
Abstract: Heart fatty acid binding protein (HFABP) has been proposed as a putative marker for dementia disorders. In order to evaluate the performance of this protein as an early marker of Alzheimer’s disease (AD), we analyzed HFABP level and the classical biomarkers amyloid-β (Aβ)1-42, total tau (t-tau), and phosphorylated tau (p-tau) in cerebrospinal fluid (CSF) of patients with mild cognitive impairment (MCI) followed up for four years (n =41), AD (n = 32), and subjects with other neurological diseases without dementia (OND, n=25). HFABP levels were higher in AD patients and in MCI converting to AD (MCI-AD) with respect to OND and to cognitively stable MCI patients (MCI-MCI). The receiver operator characteristics analysis for HFABP alone showed a sensitivity of 87% and a specificity of 81% for AD versus OND (area under the curve, AUC = 0.83); sensitivity and specificity were 46% and 94%, respectively, when comparing MCI-MCI versus MCI-AD. CSF HFABP levels showed a strong positive correlation with both t-tau and p-tau. Interestingly, the ratio between HFABP and Aβ1-42 improved the performance in distinguishing AD from OND (sensitivity: 90%; specificity 82%, AUC=0.89), and gave the best accuracy in discriminating MCI-AD from MCI-MCI (sensitivity: 80%; specificity 100%, AUC=0.90). Survival analysis by means of Kaplan-Meier curve showed a significantly higher proportion of MCI patients converting to AD in the group with higher values of HFABP/Aβ1-42 ratio (cut-off =0.7). A significant correlation between HFABP/Aβ1-42 ratio and MMSE annual decrease rate was also documented (p < 0.0001). HFABP /Aβ1-42 ratio might be a useful predictor of conversion in MCI patients.
Supplementary Data for Chiasserini et al. article (PDF)
Xuesong Chen, John F. Wagener, Daniel H. Morgan, Liang Hui, Othman Ghribi and Jonathan D. Geiger (Handling Associate Editor: Rudy Castellani)
Endolysosome Mechanisms Associated with Alzheimer’s Disease-like Pathology in Rabbits Ingesting Cholesterol-Enriched Diet
Abstract: Alzheimer’s disease (AD) is characterized clinically by progressive disturbances in memory, judgment, reasoning, and olfaction, and pathologically by loss of synaptic integrity, extracellular accumulations of amyloid-β (Aβ) containing plaques, and intraneuronal tangles composed of hyperphosphorylated tau. Endolysosome dysfunction is one of the earliest pathological features of AD and cholesterol, a known risk factor for sporadic AD, is up-taken into neurons via receptor-mediated endocytosis. Accordingly, we determined the extent to which endolysosome dysfunction is associated with pathological features observed in rabbits fed cholesterol-enriched diet; a well-characterized model of sporadic AD. Olfactory bulbs were taken from rabbits fed for 12 weeks a diet enriched with 2% cholesterol and endolysosome morphology and function as well as AD-like pathology were investigated using enzyme activity measurements, immunoblotting and immunostaining techniques. In olfactory bulbs of rabbits fed cholesterol-enriched diet, we observed enlarged endolysosomes containing increased accumulations of Apo B containing cholesterol and increased accumulations of synaptophysin, Aβ, and phosphorylated tau. Cholesterol-enriched diet also decreased significantly specific enzyme activities of the endolysosome enzymes acid phosphatase and cathepsin D. Decreased synaptic area was present in olfactory bulbs of cholesterol-fed rabbits as indicated by significant decreases in protein expression levels of the synaptic area marker protein synaptophysin. Our results suggest strongly that elevated circulating cholesterol plays an important role in the pathogenesis of AD, and that alterations in endolysosome structure and function are associated with cholesterol diet-induced AD-like pathology.
Breno Satler Diniz1, Antonio Lucio Teixeira1, Elida Benquique Ojopi, Leda Leme Talib, Vanessa Amaral Mendonça, Wagner Farid Gattaz, Orestes Vicente Forlenza 1Authors contributed equally to this work.
Higher Serum sTNFR1 Level Predicts Conversion from Mild Cognitive Impairment to Alzheimer’s Disease
Abstract: The activation of inflammatory cascades has been consistently demonstrated in the pathophysiology of Alzheimer’s disease (AD). Among several putative neuroinflammatory mechanisms, the tumor necrosis factor α (TNF-α) signaling system has a central role in this process. Recent evidence indicates that the abnormal production of inflammatory factors may accompany the progression from mild cognitive impairment (MCI) to dementia. We aimed to examine serum levels of TNF-α and its soluble receptors (sTNFR1 and sTNFR2) in patients with MCI and AD as compared to cognitively unimpaired elderly subjects. We further aimed to investigate whether abnormal levels of these cytokines predict the progression from MCI to AD upon follow-up. We utilized cross-sectional determination of serum levels of TNF-α, sTNFR1, and sTNFR2 (ELISA method) in a test group comprising 167 older adults (31 AD, 72 MCI, and 64 healthy controls), and longitudinal reassessment of clinical status after 18.9 ± 10.0 months. At baseline, there were no statistically significant differences in serum TNF-α, sTNFR1, and sTNFR2 between patients with MCI and AD as compared to controls. Nevertheless, patients with MCI who progressed to AD had significantly higher serum sTNFR1 levels as opposed to patients who retained the diagnosis of MCI upon follow-up (p=0.03). Cox regression analysis showed that high serum sTNFR1 levels predicted the conversion from MCI to AD (p=0.003), whereas no significant differences were found with respect to serum levels of TNF-α and sTNFR2. Abnormal activation of TNF-α signaling system, represented by increased expression of sTNFR1, is associated with a higher risk of progression from MCI to AD.
Shufen Chen, Kirk Townsend, Terry E. Goldberg, Peter Davies, Concepcion Conejero-Goldberg
MAPT Isoforms: Differential Transcriptional Profiles Related to 3R and 4R Splice Variants
Abstract: Tau aggregation in neurofibrillary tangles is a pathological hallmark in tauopathies including Alzheimer’s disease (AD). The predominant aggregation of certain MAPT (tau gene) isoforms, either the 4-repeat (4R tau) or the 3-repeat (3R tau) isoform has been widely described in tauopathies. Alterations of the 4R tau to 3R tau ratio may be a key for tau-related neurodegeneration. To study the biological consequences in expression between tau splicing isoforms 4R and 3R, we analyzed the main neurobiological effects of inclusion of the repeat region coded by exon 10 in MAPT. We compared the transcriptional profiles of the 4R tau isoforms to 3R tau isoforms using whole-genome gene expression profiling microarrays using human neuroblastoma SH-SY5Y cell lines overexpressing either human 4R tau and 3R tau isoforms. We identified 68 transcripts that differed significantly (at p<0.001) between 4R and 3R isoforms as conditioned on a second variant, the so-called 2N inclusion. We extended these findings in a 2x2 ANOVA to examine interaction effects of these variants. Transcripts involved in embryonic development were downregulated when exon 10 was present, while transcripts related to outgrowth of neurites were generally upregulated. An important pathway implicated in AD also differed between the 3R and 4R cell lines, Wnt signaling. These studies demonstrate expression differences between MAPT isoforms 4R tau and 3R tau due to the inclusion/exclusion of the repeat region coded for by exon 10. Our data add to complex findings on the role of 3R/4R in normal and abnormal neuronal function and highlight several molecular mechanisms that might drive neurodegeneration, or perhaps, set the stage for it.
Supplementary Data for Chen et al. article (PDF)
Mary C. Tierney, Rahim Moineddin, Angela Morra, Judith Manson, Jennifer Blake
Intensity of Recreational Physical Activity throughout Life and Later Life Cognitive Functioning in Women
Abstract: Long-term physical activity may affect risk of cognitive impairment but few studies have examined later life cognition in relation to intensity of life-long physical activity. We examined the associations between the intensity of long-term recreational physical activity and neuropsychological functioning in 90 healthy postmenopausal women on tests found to be useful in the early identification of dementia. Information was collected about their participation in strenuous and moderate activities between high school and menopause. Summary measures of long-term strenuous and moderate activity were constructed for each participant. All analyses were adjusted for relevant covariates. The six linear regression analyses showed significant positive associations between moderate activity and Wechsler Adult Intelligence Scale Revised (WAIS-R) Digit Span backward, WAIS-R Digit Symbol, and Trail Making Test Part B. Significant negative relationships were found between strenuous activity and Rey Auditory Verbal Learning Test delayed verbal recall, Complex Figure Test delayed visual memory, WAIS-R Digit Span backward, category fluency, and WAIS-R Digit Symbol. The associations found in the present study raise the speculation that while moderate activity may be protective, long-term strenuous activity before menopause may lower cognitive performance later in life. These results support further investigation of the effects of life-long exercise intensity on cognition in later life.
Annapaola Prestia, Valeria Drago, Paul E. Rasser, Matteo Bonetti, Paul M. Thompson, Giovanni B. Frisoni
Cortical Changes in Incipient Alzheimer’s Disease
Abstract: Mild cognitive impairment (MCI) is defined by memory impairment with no impact on daily activities. 10 to 15% of MCI convert to Alzheimer’s disease (AD) per year. While structural changes in the cortex of AD patients have been extensively investigated, fewer studies analyzed changes in the years preceding conversion. 46 MCI patients and 20 healthy controls underwent structural 1.0T-weighted high-resolution MR scans at baseline and after 1.4 (SD 0.3) years. All subjects were assessed yearly for up to 4 years with a comprehensive neuropsychological battery. Sixteen of the 46 patients converted to AD (cMCI) while 30 remained stable (sMCI). An accurate voxel-based statistical mesh-model technique (cortical pattern matching) with a related region-of-interest analysis based on networks defined from a Brodmann area atlas (BAs) were used to map gray matter changes over time. At baseline, cMCI patients had 10 to 30% less cortical gray matter volume than healthy controls in regions known to be affected by AD pathology (entorhinal, temporoparietal, posterior cingulate, and orbitofrontal cortex, p=0.0001). Over time, cMCI patients lost more gray matter than sMCI in all brain areas but mainly in the olfactory and in the polysynaptic hippocampal network (more than 8% gray matter loss, p<0.024). sMCI patients had 10 to 20% less volume than controls in the posterior cingulate and orbitofrontal cortex (p<0.008) although their progression over time was significantly slower than cMCI. AD patients in the MCI stage show greater gray matter loss in the olfactory and polysynaptic hippocampal network. These findings are in line with neuropathological knowledge.
Supplementary Data for Prestia et al. article (PDF)
Yoriko Tokita, Kentaro Kaji, Jun Lu, Yoshio Okura, Kuniko Kohyama and Yoh Matsumoto
Assessment of Non-Viral Amyloid-β DNA Vaccines on Amyloid-β Reduction and Safety in Rhesus Monkeys
Abstract: We recently demonstrated that newly developed non-viral amyloid-β (Aβ) DNA vaccines are safe and effective in reducing Aβ burdens in the brains of Alzheimer’s disease (AD) model mice. The present study was undertaken to examine whether DNA vaccines effectively and safely reduce Aβ deposition in the brain of rhesus monkeys. For this purpose, DNA vaccines or empty vector at a dose of 3 mg were injected intramuscularly on a biweekly basis into rhesus monkeys (15-18 years old). Before and during vaccination, blood was drawn once a month and used for hematological and biochemical examinations. Six months after the first vaccination, it was demonstrated that anti-Aβ antibodies in plasma of vaccinated monkeys were significantly elevated than that of control monkeys. Immunohistochemical examinations revealed that DNA vaccination reduced the Aβ burden to approximately 50% of that found in control monkeys (p = 0.026). There was neither inflammation nor microhemorrhage in the brain and no significant changes in cytokine and chemokine levels in the blood throughout the observation period. Taken together, DNA vaccination to monkeys is safe and effective in Aβ reduction and provides useful information for performing preclinical and clinical trials.
Hannah Tayler*, Thomas Fraser*, J. Scott Miners, Patrick G Kehoe, Seth Love *These authors contributed equally to the manuscript.
Oxidative Balance in Alzheimer’s Disease: Relationship to APOE, Braak Tangle Stage, and the Concentrations of Soluble and Insoluble Amyloid-β
Abstract: Oxidative damage is greater in brain tissue from patients with Alzheimer’s disease (AD) than age-matched controls. The timing of this damage in relation to other pathogenic processes in AD remains unclear. We have examined the relationship of lipid peroxidation (thiobarbituric acid-reactive substances; TBARS) and antioxidant capacity (Trolox-equivalent) to APOE status, Braak tangle stage, amyloid-β (Aβ) plaque load, and the concentration of soluble and insoluble forms of Aβ, post-synaptic and dendritic spine proteins PSD95 and drebrin, β-secretase and Aβ-degrading enzymes neprilysin (NEP), insulin-degrading enzyme (IDE), and angiotensin-converting enzyme (ACE), in frontal, temporal, and parietal cortex from AD and control brains. Antioxidant capacity was significantly elevated in AD and directly related to disease severity as indicated by Braak tangle stage and the amount of insoluble Aβ. APOE ε4 was associated with increased antioxidant capacity in AD but not controls. In contrast, apart from a reduction in TBARS in Braak stages III-IV in frontal cortex, this measure of oxidative damage did not change significantly with any indicator of disease severity. It was, however, higher in APOE ε4-positive than ε4-negative AD patients and correlated with β-secretase activity. Neither antioxidant capacity nor oxidative damage was related to the level of PSD95 or drebin or the activity of NEP, IDE, or ACE. Antioxidant capacity in AD is closely related to the level of insoluble Aβ and increases with pathological progression of the disease. Increased β-secretase activity associated with oxidative stress is likely to contribute to the accumulation of Aβ and this, in turn, to induce antioxidant capacity.