Journal of Alzheimer's Disease - Volume 28, issue 2

Authors: Velayudhan, Latha | Killick, Richard | Hye, Abdul | Kinsey, Anna | Güntert, Andreas | Lynham, Steven | Ward, Malcolm | Leung, Rufina | Lourdusamy, Anbarasu | To, Alvina W.M. | Powell, John | Lovestone, Simon

Article Type: Research Article

Abstract: Diagnosis of the progressive neurodegenerative disorder Alzheimer's disease (AD) can only definitively be made postmortem. The most promising AD biomarkers identified to date are found in cerebrospinal fluid (CSF). Among these, one of the most interesting candidates is transthyretin (TTR), the carrier of thyroxine and retinol, which also binds with amyloid-β (Aβ), and it has been suggested that it protects against Aβ deposition. A biomarker detectable in plasma would have great diagnostic value and could be of use for determining disease progression and the monitoring of therapeutic efficacy due to its greater accessibility over CSF-based markers. We aimed to validate …TTR as a prognostic marker in AD and to determine its relation with cognitive measures. We examined the plasma protein levels of TTR in 90 people with late-onset AD and 50 age-matched non-demented controls (NDC) by immunoblotting and found lower plasma TTR levels in AD compared to NDC (p = 0.004). We then quantified plasma TTR by enzyme-linked immunosorbent assays in a larger independent cohort (n = 270) including subjects with mild to severe AD. Plasma TTR levels were significantly lower in AD cases with rapid cognitive decline and with severe cognitive impairment. Regression analyses showed plasma TTR levels also predicted cognitive decline over the ensuing 6 months. These data indicate that plasma TTR is a strong candidate AD biomarker that should be included in the development of blood based biomarker panels for disease diagnosis and also suggests that plasma TTR is a marker of disease severity and progression. Show more

Keywords: Alzheimer's disease, cognitive impairment, plasma proteins, transthyretin

DOI: 10.3233/JAD-2011-110611

Citation: Journal of Alzheimer's Disease, vol. 28, no. 2, pp. 369-375, 2012

Authors: Gerrish, Amy | Russo, Giancarlo | Richards, Alexander | Moskvina, Valentina | Ivanov, Dobril | Harold, Denise | Sims, Rebecca | Abraham, Richard | Hollingworth, Paul | Chapman, Jade | Hamshere, Marian | Pahwa, Jaspreet Singh | Dowzell, Kimberley | Williams, Amy | Jones, Nicola | Thomas, Charlene | Stretton, Alexandra | Morgan, Angharad R. | Lovestone, Simon | Powell, John | Proitsi, Petroula | Lupton, Michelle K. | Brayne, Carol | Rubinsztein, David C. | Gill, Michael | Lawlor, Brian | Lynch, Aoibhinn | Morgan, Kevin | Brown, Kristelle S. | Passmore, Peter A. | Craig, David | McGuinness, Bernadette | Todd, Stephen | Johnston, Janet A. | Holmes, Clive | Mann, David | Smith, A. David | Love, Seth | Kehoe, Patrick G. | Hardy, John | Mead, Simon | Fox, Nick | Rossor, Martin | Collinge, John | Maier, Wolfgang | Jessen, Frank | Kölsch, Heike | Heun, Reinhard | Schürmann, Britta | Bussche, Hendrik van den | Heuser, Isabella | Kornhuber, Johannes | Wiltfang, Jens | Dichgans, Martin | Frölich, Lutz | Hampel, Harald | Hüll, Michael | Rujescu, Dan | Goate, Alison M. | Kauwe, John S. K | Cruchaga, Carlos | Nowotny, Petra | Morris, John C. | Mayo, Kevin | Livingston, Gill | Bass, Nicholas J. | Gurling, Hugh | McQuillin, Andrew | Gwilliam, Rhian | Deloukas, Panagiotis | Davies, Gail | Harris, Sarah E. | Starr, John M. | Deary, Ian J. | Al-Chalabi, Ammar | Shaw, Christopher E. | Tsolaki, Magda | Singleton, Andrew B. | Guerreiro, Rita | Mühleisen, Thomas W. | Nöthen, Markus M. | Moebus, Susanne | Jöckel, Karl-Heinz | Klopp, Norman | Wichmann, H-Erich | Carrasquillo, Minerva M | Pankratz, V Shane | Younkin, Steven G. | Jones, Lesley | Holmans, Peter A | O'Donovan, Michael C. | Owen, Michael J. | Williams, Julie

Article Type: Research Article

Abstract: Rare mutations in AβPP, PSEN1, and PSEN2 cause uncommon early onset forms of Alzheimer's disease (AD), and common variants in MAPT are associated with risk of other neurodegenerative disorders. We sought to establish whether common genetic variation in these genes confer risk to the common form of AD which occurs later in life (>65 years). We therefore tested single-nucleotide polymorphisms at these loci for association with late-onset AD (LOAD) in a large case-control sample consisting of 3,940 cases and 13,373 controls. Single-marker analysis did not identify any variants that reached genome-wide significance, a result which is supported by other recent …genome-wide association studies. However, we did observe a significant association at the MAPT locus using a gene-wide approach (p = 0.009). We also observed suggestive association between AD and the marker rs9468, which defines the H1 haplotype, an extended haplotype that spans the MAPT gene and has previously been implicated in other neurodegenerative disorders including Parkinson's disease, progressive supranuclear palsy, and corticobasal degeneration. In summary common variants at AβPP, PSEN1, and PSEN2 and MAPT are unlikely to make strong contributions to susceptibility for LOAD. However, the gene-wide effect observed at MAPT indicates a possible contribution to disease risk which requires further study. Show more

Keywords: Alzheimer's disease, amyloid-β protein precursor, genetics, human, MAPT protein, PSEN1 protein, PSEN2 protein

DOI: 10.3233/JAD-2011-110824

Citation: Journal of Alzheimer's Disease, vol. 28, no. 2, pp. 377-387, 2012

Authors: Sun, Jiya | Feng, Xuemei | Liang, Dapeng | Duan, Yong | Lei, Hongxing

Article Type: Research Article

Abstract: A central issue in the field of Alzheimer's disease (AD) is to separate the cause from the consequence among many observed pathological features, which may be resolved by studying the time evolution of these features at distinctive stages. In this work, comprehensive analyses on transcriptome studies of human postmortem brain tissues from AD patients at distinctive stages revealed stepwise breakdown of the cellular machinery during the progression of AD. At the early stage of AD, the accumulation of amyloid-β oligomers and amyloid plaques leads to the down-regulation of biosynthesis and energy metabolism. At the intermediate stage, the progression of the …disease leads to enhanced signal transduction, while the late stage is characterized by elevated apoptosis. The down-regulation of energy metabolism in AD has been considered by many as a consequence of mitochondrion damage due to oxidative stress. However, the non-existence of enhanced response to oxidative stress and the revelation of intriguing down-regulation patterns of the electron-transport chain at different stages suggest otherwise. In contrast to the damage-themed hypothesis, we propose that the down-regulation of energy metabolism in AD is a protective response of the neurons to the reduced level of nutrient and oxygen supply in the microenvironment. The elevated apoptosis at the late stage of AD is triggered by the conflict between the low level of energy metabolism and high level of regulatory and repair burden. This new hypothesis has significant implication for pharmaceutical intervention of Alzheimer's disease. Show more

Keywords: Brain tissue, microarray, signal transduction, neuronal cell death

DOI: 10.3233/JAD-2011-111313

Citation: Journal of Alzheimer's Disease, vol. 28, no. 2, pp. 389-402, 2012

Authors: Wei, Zelan | Gabriel, Geraldine G. | Rui, Lewei | Cao, Xia | Pennington, Paul R. | Chlan-Fourney, Jennifer | Nazarali, Adil J. | Baker, Glen B. | Mousseau, Darrell D.

Article Type: Research Article

Abstract: The concentration of presenilin-1 (PS-1) protein at the mitochondrial-associated aspect of the endoplasmic reticulum supports the potential for a mitochondrial influence of PS-1. Given that carriers of certain Alzheimer's disease (AD)-related PS-1 variants are predisposed to clinical depression and that depression has been historically associated with the mitochondrial enzyme, monoamine oxidase-A (MAO-A), we investigated cortical MAO-A function in the AD-related PS-1(M146V) knock-in mouse. The MAO-A system was clearly altered in the PS-1(M146V) mouse as revealed by (a) a mismatch between MAO-A protein expression and MAO-A activity; (b) changes in MAO-A-mediated monoaminergic neurotransmitter metabolism; (c) changes in non-cognitive behavior following treatment …with the irreversible MAO-A inhibitor clorgyline; and (d) an increase in the potency of clorgyline in these same mice. We next investigated whether PS-1(M146V) could be influencing MAO-A directly. We observed (a) an enhanced MAO-A activity in necropsied PS-1(M146V) mouse cortical extracts incubated with DAPT (a PS-1 substrate-competitor); (b) the proximity of PS-1 with MAO-A and mitochondrial markers in cortical sections and in primary cortical neurons; (c) the co-segregation and co-immunoprecipitation of PS-1 and MAO-A within the mitochondrial fraction; and (d) the co-immunoprecipitation of overexpressed PS-1(M146V) and MAO-A proteins from N2a lysates. The PS-1(ΔEx9) and PS-1(D257A) variants, known to have low substrate-binding capacity, co-immunoprecipitated weakly with MAO-A. These combined data support a physical interaction between PS-1 and MAO-A that could influence MAO-A activity and contribute to the monoaminergic disruptions common to disorders as seemingly diverse as depression and AD. Show more

Keywords: Alzheimer's disease, depression, mitochondria, monoamine oxidase, secretase

DOI: 10.3233/JAD-2011-111241

Citation: Journal of Alzheimer's Disease, vol. 28, no. 2, pp. 403-422, 2012

Authors: Lee, Sangmook | Lemere, Cynthia A. | Frost, Jeffrey L. | Shea, Thomas B.

Article Type: Research Article

Abstract: S-adenosyl methionine (SAM) contributes to multiple pathways in neuronal homeostasis, several of which are compromised in age-related neurodegeneration and Alzheimer's disease. Dietary supplementation of transgenic mice with SAM maintained acetylcholine levels, cognitive performance, oxidative buffering capacity, and phosphatase activity, and reduced aggression, calcium influx, endogenous PS-1 expression, γ-secretase activity, and levels of amyloid-β (Aβ) and phospho-tau. Herein, we examined whether or not SAM could delay neuropathology in 3xTg-AD mice, which harbor mutant genes for human AβPP, PS-1 and tau. Mice received a standard AIN-76 diet with or without SAM (100 mg/kg diet) for 1 month commencing at 10 months of …age or for 3 months commencing at 12.5 months of age; mice were sacrificed and examined for Aβ and tau neuropathology at 11 and 15.5 months of age, respectively. SAM supplementation reduced hippocampal intracellular AβPP/Aβ and phospho-tau immunoreactivity to a similar extent at both sampling intervals. Supplementation reduced the number of extracellular Aβ deposits by 80% (p < 0.01) at 11 months of age after 1 month of treatment but only by 24% (p < 0.34) at 15.5 months of age after 3 months of treatment. As anticipated, neurofibrillary tangles were not observed in mice at these young ages; however, supplementation reduced levels of phospho-tau and caspase-cleaved tau within Sarkosyl-insoluble preparations in mice at 15.5 months of age. These limited analyses indicate that SAM can modulate the time course of AD neuropathology, and support further long-term analyses. Show more

Keywords: Alzheimer's disease, amyloid-β, neurofibrillary tangles, S-adenosylmethionine, senile plaques, tau

DOI: 10.3233/JAD-2011-111025

Citation: Journal of Alzheimer's Disease, vol. 28, no. 2, pp. 423-431, 2012

Authors: Huang, Jeffrey Y. | Hafez, Daniel M. | James, Bryan D. | Bennett, David A. | Marr, Robert A.

Article Type: Research Article

Abstract: Neprilysin-2 (NEP2), a close homolog of neprilysin (NEP), degrades amyloid-β (Aβ) and serves an important role in clearing Aβ in vivo. We measured NEP2 and NEP mRNA levels from non-impaired (NI), mild cognitive impaired (MCI), and clinical Alzheimer's disease (AD) subjects in the mid-temporal gyrus, mid-frontal gyrus, caudate, and cerebellum. NEP2 activity levels were also determined. Our results indicate that NEP2 and NEP mRNA expression is altered in MCI subjects relative to NI subjects in AD-susceptible regions. NEP2 enzymatic activity was lowered in association with MCI and AD and was positively associated with cognitive function, independent of diagnostic category. Our …finding that NEP2 expression and activity are altered in MCI is significant as these changes may potentially serve as preclinical markers for AD and reduced NEP2 activity may be associated with the development of AD. Show more

Keywords: Alzheimer's disease, amyloid-β peptide, biomarker, human brain, neprilysin, neprilysin-2

DOI: 10.3233/JAD-2011-111307

Citation: Journal of Alzheimer's Disease, vol. 28, no. 2, pp. 433-441, 2012

Authors: Darreh-Shori, Taher | Siawesh, Manar | Mousavi, Malahat | Andreasen, Niels | Nordberg, Agneta

Article Type: Research Article

Abstract: Butyrylcholinesterase K (BCHE-K) is associated with increased risk of developing Alzheimer's disease (AD) in apolipoprotein ε (APOE4) carriers, while among APOE4 non-carriers BCHE-K appears to be protective. Nonetheless, pure pharmacogenetic reports have provided conflicting results. To provide insights about these controversies, we combined BCHE-K pharmacogenetic observations in AD patients (n = 179) with proteomic and enzymatic analysis of plasma, cerebrospinal fluid (CSF), or both samples. We found that BCHE-K genotype was overrepresented among the AD patients (χ2 = 14.21, p < 0.0001). Plasma BuChE activity was gene dose-dependently 20–50% less among K-carriers (p < 0.001). CSF BuChE activity did …not show such robust K-gene dosage-dependency, because K homozygotes (n = 9) had 30–40% less activity compared to both non-carriers (n = 78, p < 0.01) and heterozygotes (n = 42, p < 0.09). CSF ApoE protein expression was also altered by presence of K-allele (p < 0.001, n = 129). Mutually, APOE4 altered phenotypic display of BuChE variants in CSF (p < 0.01, n = 129). In absence of APOE4, CSF BuChE activity was essentially indistinguishable among K-carriers (n = 16) and non-carriers (n = 17, p < 0.8) although the K-carriers had 24–39% less circulating BuChE protein. In contrast in presence of APOE4, the K-carriers (n = 35) had K allele dose-dependently a BuChE phenotype with 14–46% reduced activity compared to K non-carriers (p < 0.001, n = 59), despite an essentially identical BChE concentration in CSF (1 ± 4%, p < 0.8). Pattern of the patients' cognitive performance in MMSE closely resembled the APOE4-derived phenotypic display of BuChE variants. APOE4-dependent outcome of BCHE-K genotype as AD risk factor arises through a differential phenotypic modulation of BuChE. Future pharmacogenetic studies should include assessment of the subjects' true phenotypic display of BuChE. Show more

Keywords: Acetylcholinesterase, Alzheimer's disease, apolipoprotein ε4 genotype, cutyrylcholinesterase K variant, central cholinergic system, pharmacogenetic

DOI: 10.3233/JAD-2011-111088

Citation: Journal of Alzheimer's Disease, vol. 28, no. 2, pp. 443-458, 2012

Authors: Avdesh, Avdesh | Martin-Iverson, Mathew T. | Mondal, Alinda | Chen, Mengqi | Askraba, Sreten | Morgan, Newman | Lardelli, Michael | Groth, David M. | Verdile, Giuseppe | Martins, Ralph N.

Article Type: Research Article

Abstract: There is growing interest in using zebrafish (Danio rerio) as a model of neurodegenerative disorders such as Alzheimer's disease. A zebrafish model of tauopathies has recently been developed and characterized in terms of presence of the pathological hallmarks (i.e., neurofibrillary tangles and cell death). However, it is also necessary to validate these models for function by assessing learning and memory. The majority of tools to assess memory and learning in animal models involve visual stimuli, including color preference. The color preference of zebrafish has received little attention. To validate zebrafish as a model for color-associated-learning and memory, it is necessary …to evaluate its natural preferences or any pre-existing biases towards specific colors. In the present study, we have used four different colors (red, yellow, green, and blue) to test natural color preferences of the zebrafish using two procedures: Place preference and T-maze. Results from both experiments indicate a strong aversion toward blue color relative to all other colors (red, yellow, and green) when tested in combinations. No preferences or biases were found among reds, yellows, and greens in the place preference procedure. However, red and green were equally preferred and both were preferred over yellow by zebrafish in the T-maze procedure. The results from the present study show a strong aversion towards blue color compared to red, green, and yellow, with yellow being less preferred relative to red and green. The findings from this study may underpin any further designing of color-based learning and memory paradigms or experiments involving aversion, anxiety, or fear in the zebrafish. Show more

Keywords: Alzheimer's disease, color preference, learning and memory, place preference, T-maze, zebrafish

DOI: 10.3233/JAD-2011-110704

Citation: Journal of Alzheimer's Disease, vol. 28, no. 2, pp. 459-469, 2012

Authors: Zhou, Jin-Wu | Cheng, Xiao-Rui | Cheng, Jun-Ping | Zhou, Wen-Xia | Zhang, Yong-xiang

Article Type: Research Article

Abstract: The senescence accelerated mouse prone 8 (SAMP8), an animal model of Alzheimer's disease, has amyloid-β deposition in the brain. This study showed that β-secretase activity increased age-dependently in cerebral cortex of SAMP8 and SAMP8's control, SAM resistant/1 (SAMR1), and was higher in the hippocampus of SAMP8 than that of age-matched SAMR1. Cathepsin D activity also increased age-dependently in the cerebral cortex of SAMP8. There was no significant difference between SAMP8 and SAMR1 with regards to activity of cathepsin B. β-secretase activity had a positive correlation with cathepsin D activity in the cerebral cortex of SAMR1 and SAMP8. There was a …tendency toward decreased mRNA expression of BACE1, cathepsin D, and cathepsin B in the hippocampus of SAMR1 and SAMP8 with aging. mRNA expression of cathepsin B was elevated significantly in the cerebral cortex of SAMP8 at 2 and 6 months of age compared to that of age-matched SAMR1, and similarly so was cathepsin D at 2 months. This data showed there was no correlation between mRNA expression and activity of β-secretase, cathepsin D, and cathepsin B in the brain of SAMR1 and SAMP8 with age. These findings also indicate it was cathepsin D, not cathepsin B, that contributed to β-secretase activity and the increased amyloid-β production in the SAMP8 brain. In addition, it was necessary to take into account the target selectivity of BACE1 and cathepsin D, not necessary to detect the mRNA expression, when SAMP8 was used as an animal model to determine the effect of β-secretase inhibitor. Show more

Keywords: β-secretase, cerebral cortex, hippocampus, senescence-accelerated mouse

DOI: 10.3233/JAD-2011-111469

Citation: Journal of Alzheimer's Disease, vol. 28, no. 2, pp. 471-480, 2012

Authors: White, Lon R.

Article Type: Research Article

DOI: 10.3233/JAD-2011-111269

Citation: Journal of Alzheimer's Disease, vol. 28, no. 2, pp. 481-483, 2012