Journal of Alzheimer's Disease - Volume 33, issue 4

Authors: Hughes, Timothy M. | Rosano, Caterina | Evans, Rhobert W. | Kuller, Lewis H.

Article Type: Review Article

Abstract: Cholesterol metabolism is implicated in the etiology of Alzheimer's disease (AD) and amyloid production in the brain. While brain cholesterol cannot be measured directly in vivo, the oxysterol, 24S-hydroxycholesterol (24-OHC), is the predominant metabolite of brain cholesterol and can be measured in the blood. The aim of this review is to evaluate plasma 24-OHC as a potential biomarker of AD risk and discuss factors related to its levels in the brain and blood. This systematic review examines studies published between 1950 and June 2012 that examined the relationship between plasma 24-OHC, cognition, brain structure, and dementia using the following key …words (“24S-hydroxycholesterol” or “24-hydroxycholesterol”) and (“Brain” or “Cognitive”). We found a total of 28 studies of plasma 24-OHC and neurodegenerative disease, including a subset of 12 that used dementia as a clinical endpoint. These studies vary in the direction of the observed associations. Results suggest plasma 24-OHC may be higher in the early stages of cognitive impairment and lower in more advanced stages of AD when compared to cognitively normal controls. Measures of 24-OHC in the blood may be an important potential marker for cholesterol metabolism in the brain and risk of AD. Further studies of plasma 24-OHC and dementia must account for the stage of disease, establish the temporal trends in oxysterol concentrations, and employ neuroimaging modalities to assess the structural and metabolic changes occurring in the brain prior to the onset of cognitive impairment. Show more

Keywords: Alzheimer's disease, brain, dementia, 24-hydroxycholesterol, 24S-hydroxycholesterol, oxysterols

DOI: 10.3233/JAD-2012-121585

Citation: Journal of Alzheimer's Disease, vol. 33, no. 4, pp. 891-911, 2013

Authors: Hanford, Nicholas | Figueiro, Mariana

Article Type: Review Article

Abstract: Sleep disturbances are common in persons with Alzheimer's disease or related dementia (ADRD), resulting in a negative impact on the daytime function of the affected person and on the wellbeing of caregivers. The sleep/wake pattern is directly driven by the timing signals generated by a circadian pacemaker, which may or may not be perfectly functioning in those with ADRD. A 24-hour light/dark pattern incident on the retina is the most efficacious stimulus for entraining the circadian system to the solar day. In fact, a carefully orchestrated light/dark pattern has been shown in several controlled studies of older populations, with and …without ADRD, to be a powerful non-pharmacological tool to improve sleep efficiency and consolidation. Discussed here are research results from studies looking at the effectiveness of light therapy in improving sleep, depression, and agitation in older adults with ADRD. A 24-hour lighting scheme to increase circadian entrainment, improve visibility, and reduce the risk of falls in those with ADRD is proposed, and future research needs are discussed. Show more

Keywords: Alzheimer's disease, circadian rhythm, lighting design, light therapy, sleep, wayfinding

DOI: 10.3233/JAD-2012-121645

Citation: Journal of Alzheimer's Disease, vol. 33, no. 4, pp. 913-922, 2013

Authors: O'Dowd, Seán T. | Ardah, Mustafa T. | Johansson, Per | Lomakin, Aleksey | Benedek, George B. | Roberts, Kinley A. | Cummins, Gemma | El Agnaf, Omar M. | Svensson, Johan | Zetterberg, Henrik | Lynch, Timothy | Walsh, Dominic M.

Article Type: Short Communication

Abstract: Elevated cerebrospinal fluid concentrations of tau discriminate Alzheimer's disease from other neurodegenerative conditions. The reasons for this are unclear. While commercial assay kits are widely used to determine total-tau concentrations, little is known about their ability to detect different aggregation states of tau. We demonstrate that the leading commercial enzyme-linked immunosorbent assay reliably detects aggregated and monomeric tau and evinces good recovery of both species when added into cerebrospinal fluid. Hence, the disparity between total-tau levels encountered in Alzheimer's disease and other neurodegenerative conditions is not due to differential recognition of tau assembly forms or the extent of degeneration.

Keywords: Alzheimer's disease, cerebrospinal fluid, ELISA, tau

DOI: 10.3233/JAD-2012-121393

Citation: Journal of Alzheimer's Disease, vol. 33, no. 4, pp. 923-928, 2013

Authors: Choo, IL Han | Ni, Ruiqing | Schöll, Michael | Wall, Anders | Almkvist, Ove | Nordberg, Agneta

Article Type: Research Article

Abstract: The biomarker-based new diagnostic criteria have been proposed for Alzheimer's disease (AD) spectrum. However, any biomarker alone has not been known to have satisfactory AD predictability. We explored the best combination model with baseline demography, neuropsychology, 18 F-fluorodeoxyglucose positron emission tomography (FDG-PET), cerebrospinal fluid (CSF) biomarkers, and apolipoprotein E (APOE) genotype evaluation to predict progression to AD in mild cognitive impairment (MCI) patients. A longitudinal clinical follow-up (mean, 44 months; range, 1.6–161.7 months) of MCI patients was done. Among 83 MCI patients, 26 progressed to AD (MCI-AD) and 51 did not deteriorate (MCI-Stable). We applied that univariate and multivariate logistic …regression analyses, and multistep model selection for AD predictors including biomarkers. In univariate logistic analysis, we selected age, Rey Auditory Verbal Retention Test, parietal glucose metabolic rate, CSF total tau, and presence or not of at least one APOE ε4 allele as predictors. Through multivariate stepwise logistic analysis and model selection, we found the combination of parietal glucose metabolic rate and total tau representing the best model for AD prediction. In conclusion, our findings highlight that the combination of regional glucose metabolic assessment by PET and CSF biomarkers evaluation can significantly improve AD predictive diagnostic accuracy of each respective method. Show more

Keywords: Biomarkers, combination, mild cognitive impairment, predictor

DOI: 10.3233/JAD-2012-121489

Citation: Journal of Alzheimer's Disease, vol. 33, no. 4, pp. 929-939, 2013

Authors: Inestrosa, Nibaldo C. | Carvajal, Francisco J. | Zolezzi, Juan M. | Tapia-Rojas, Cheril | Serrano, Felipe | Karmelic, Daniel | Toledo, Enrique M. | Toro, Andrés | Toro, Jessica | Santos, Manuel J.

Article Type: Research Article

Abstract: Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive deterioration of cognitive abilities, accumulation of the amyloid-β peptide (Aβ), increase of oxidative stress, and synaptic alterations. The scavenging of reactive oxygen species through their matrix enzyme catalase is one of the most recognized functions of peroxisomes. The induction of peroxisome proliferation is attained through different mechanisms by a set of structurally diverse molecules called peroxisome proliferators. In the present work, a double transgenic mouse model of AD that co-expresses a mutant human amyloid-β protein precursor (AβPPswe) and presenilin 1 without exon 9 (PS1dE9) was utilized in order to …assess the effect of peroxisomal proliferation on Aβ neurotoxicity in vivo. Mice were tested for spatial memory and their brains analyzed by cytochemical, electrophysiological, and biochemical methods. We report here that peroxisomal proliferation significantly reduces (i) memory impairment, found in this model of AD; (ii) Aβ burden and plaque-associated acetylcholinesterase activity; (iii) neuroinflammation, measured by the extent of astrogliosis and microgliosis; and (iv) the decrease in postsynaptic proteins, while promoting synaptic plasticity in the form of long-term potentiation. We concluded that peroxisomal proliferation reduces various AD neuropathological markers and peroxisome proliferators may be considered as potential therapeutic agents against the disease. Show more

Keywords: Amyloid β-peptide, peroxisomal proliferation, spatial memory, synaptic plasticity, transgenic mice

DOI: 10.3233/JAD-2012-120397

Citation: Journal of Alzheimer's Disease, vol. 33, no. 4, pp. 941-959, 2013

Authors: Cho, Eun Bin | Seo, Sang Won | Kim, HoJeong | Lee, Jong-Min | Yoon, Uicheul | Im, Kiho | Kim, Geon Ha | Noh, Young | Cho, Hanna | Yoon, Cindy W. | Kim, Hee Jin | Na, Duk L.

Article Type: Research Article

Abstract: There are some studies identifying the association between kidney dysfunction and cognitive impairment through various mechanisms including small vessel disease. However, results concerning the relationship between kidney dysfunction and cortical atrophy have been inconsistent. Thus, we aimed to evaluate the relationship among kidney dysfunction, small vessel disease, and cortical thinning in probable Alzheimer's disease (AD) dementia patients. Patients consisted of 162 subjects with probable AD dementia who underwent high-resolution T1-weighted volumetric magnetic resonance imaging (MRI) scans using the same scanner. The estimated glomerular filtration rate (GFR) was calculated and divided into the quartiles of patients for comparison. Volume of white …matter hyperintensities (WMH) was automatically measured. Two neurologists counted the number of lacunes. Cortical thickness was measured using a surface-based method. GFR was not associated with WMH and the number of lacunes. However, the lowest quartile group of GFR (GFR 1) had cortical thinning in each lobe, compared to the highest quartile group of GFR (GFR 4). The topography of cortical thinning in the GFR 1 group was distributed predominantly in temporoparietal regions, compared to GFR 4. After further adjustment of small vessel disease MRI markers, the association between GFR and the cortical thinning remained. Our findings suggested that kidney dysfunction, represented by GFR, was related to temporoparietal thinning independent of small vessel disease in probable AD dementia patients. Show more

Keywords: Alzheimer's disease, cortical thinning, glomerular filtration rate, kidney function

DOI: 10.3233/JAD-2012-121180

Citation: Journal of Alzheimer's Disease, vol. 33, no. 4, pp. 961-968, 2013

Authors: Rossi, Giacomina | Conconi, Donatella | Panzeri, Elena | Redaelli, Serena | Piccoli, Elena | Paoletta, Laura | Dalprà, Leda | Tagliavini, Fabrizio

Article Type: Research Article

Abstract: In addition to the main function of promoting polymerization and stabilization of microtubules, other roles are being attributed to tau, now considered a multifunctional protein. In particular, previous studies suggest that tau is involved in chromosome stability and genome protection. We performed cytogenetic analysis, including molecular karyotyping, on lymphocytes and fibroblasts from patients affected by frontotemporal lobar degeneration carrying different mutations in the microtubule-associated protein tau gene, to investigate the effects of these mutations on genome stability. Furthermore, we analyzed the response of mutated lymphoblastoid cell lines to genotoxic agents to evaluate the participation of tau to DNA repair systems. …We found a significantly higher level of chromosome aberrations in mutated than in control cells. Mutated lymphocytes showed higher percentages of stable lesions, clonal and total aneuploidy (medians: 2 versus 0, p ≪ 0.01; 1.5 versus 0, p ≪ 0.01; 16.5 versus 0, p ≪ 0.01, respectively). Fibroblasts of patients showed higher percentages of stable lesions, structural aberrations and total aneuploidy (medians: 0 versus 0, p = 0.03; 5.8 versus 0, p = 0.02; 26.5 versus 12.6, p ≪ 0.01, respectively). In addition, the in depth analysis of DNA copy number variations showed a higher tendency to non-allelic homologous recombination in mutated cells. Finally, while our analysis did not support an involvement of tau in DNA repair systems, it revealed its role in stabilization of chromatin. In summary, our findings indicate a role of tau in genome and chromosome stability that can be ascribed to its function as a microtubule-associated protein as well as a protein protecting chromatin integrity through interaction with DNA. Show more

Keywords: Chromosome aberrations, DNA copy number variations, genome instability, MAPT, mutation, tau protein, tauopathies

DOI: 10.3233/JAD-2012-121633

Citation: Journal of Alzheimer's Disease, vol. 33, no. 4, pp. 969-982, 2013

Authors: Herculano, Bruno | Tamura, Minami | Ohba, Ayaka | Shimatani, Mayu | Kutsuna, Natsumaro | Hisatsune, Tatsuhiro

Article Type: Research Article

Abstract: Our goal in this study was to determine whether or not feeding young (4 months old) Alzheimer's disease model transgenic mice with a high fat diet (HFD), consisting of 32% fat, is capable of causing cognitive decline and whether treatment with β-alanyl-L-histidine (carnosine) is capable of reducing these effects. Carnosine is an endogenous antioxidant and antiglycating agent that is abundantly present in the brain and muscle tissues of vertebrates. After 8 weeks of feeding with HFD, we observed a significant decline in the contextual memory in transgenic mice fed with HFD as compared to transgenic mice fed with a normal …diet as well as to normal diet-wild type mice. Treatment with carnosine at a dose of 5 mg/day for 6 weeks was effective in preventing cognitive decline, as the transgenic group fed with HFD and treated with carnosine displayed a level of cognition comparable to controls. No differences in senile plaque load were observed between all groups. However, we observed an increase in the expression of RAGE in blood vessels as well as increased microglial activation in the hippocampus of animals fed with HFD, effects that were reversed when treated with carnosine. Given these results, there is a possibility that inflammation and cerebrovascular abnormalities might be the cause of cognitive decline in this model. Show more

Keywords: Alzheimer's disease, carnosine, high fat diet, oxidative stress

DOI: 10.3233/JAD-2012-121324

Citation: Journal of Alzheimer's Disease, vol. 33, no. 4, pp. 983-997, 2013

Authors: Kehoe, Patrick Gavin | Davies, Neil Martin | Martin, Richard Michael | Ben-Shlomo, Yoav

Article Type: Research Article

Abstract: We investigated whether angiotensin II receptor blockers and angiotensin converting enzyme inhibitors were associated with risk of mortality or inpatient hospitalization for patients with dementia compared to other antihypertensive medications. We extracted a clinical cohort of 6,290 patients with dementia from the United Kingdom General Practice Research Database, prescribed antihypertensive medication at diagnosis of dementia with around 10 years follow-up. Using survival analysis we estimated associations of exposure to antihypertensive medication with subsequent hospitalization and mortality risk, stratified by dementia type (Alzheimer's disease, vascular and other dementias). Angiotensin converting enzyme inhibitors (but not angiotensin II receptor blockers) were associated with …an increased risk of mortality in patients with Alzheimer's disease (adjusted hazard ratio: 1.19; 95% CI 1.07, 1.33, p = 0.002), but no convincing evidence of increased hospitalization. Angiotensin II receptor blockers were inversely associated with hospitalization for any form of dementia, but after adjustment for covariates, these associations became consistent with chance. Further evidence is required to either support or refute the observation that exposure to angiotensin converting enzyme inhibitors in patients with dementia is associated with increased mortality. Show more

Keywords: Alzheimer's disease, amyloid, angiotensin, dementia, hospitalization, mortality, vascular dementia

DOI: 10.3233/JAD-2012-121090

Citation: Journal of Alzheimer's Disease, vol. 33, no. 4, pp. 999-1008, 2013

Authors: Goñi, Joaquín | Cervantes, Sebastián | Arrondo, Gonzalo | Lamet, Isabel | Pastor, Pau | Pastor, María A.

Article Type: Research Article

Abstract: The aim of our study was to elucidate whether specific patterns of gray matter loss were associated with apolipoprotein E ε4 (APOE ε4) and microtubule-associated protein tau (MAPT)-H1) genetic variants in subjects with mild cognitive impairment (MCI) at a baseline visit. Gray matter voxel-based morphometry analysis of T1 magnetic resonance imaging scans were performed in 65 amnestic-MCI subjects. MCI APOE ε4 carriers compared with non-carriers showed increased brain atrophy in right hippocampus and rostral amygdala, superior and middle temporal gyrus, and right parietal operculum, including inferior frontal gyrus, inferior parietal, and supramarginal gyrus. MAPT-H1/H1 MCI carriers showed an increased bilateral …atrophy in superior frontal gyri (including frontal eye fields and left prefrontal cortex) and precentral gyrus but also unilateral left atrophy in the inferior temporal gyrus and calcarine gyrus. In addition, MCI subjects carrying both APOE ε4 and MAPT-H1/H1 variants showed gray matter loss in the supplementary motor area and right pre- and postcentral gyri. The effect of APOE ε4 on gray matter loss in right hippocampus suggests that, at least in some AD sub-types, the neuronal vulnerability could be increased in the right hemisphere. The pattern of frontal gray matter loss observed among MCI MAPT H1/H1 carriers has also been found in other tauopathies, suggesting that MCI may share etiological factors with other tauopathies. Frontal and parietal cortex vulnerability was found when adding MAPT H1/H1 and APOE ε4 effects, suggesting a synergistic effect of these variants. These results could be due to changes in APOE ε4 and MAPT expression. Show more

Keywords: APOE, genetic risk, genetics, magnetic resonance imaging, MAPT, mild cognitive impairment, single nucleotide polymorphism, tau, voxel based morphometry, Alzheimer disease

DOI: 10.3233/JAD-2012-121174

Citation: Journal of Alzheimer's Disease, vol. 33, no. 4, pp. 1009-1019, 2013