Background: Alzheimer’s disease (AD) is a neurodegenerative disorder for which there is presently no cure. As a result, there is a critical need to improve upon early detection methods through the identification of ideally non-invasive biomarkers, such as functional magnetic resonance imaging (fMRI). Recently, novel approaches to the analysis of resting-state fMRI data have been developed that focus on the moment-to-moment variability in the blood oxygen level dependent (BOLD) signal. However, the findings on BOLD signal variability have thus far been equivocal, with some findings showing decreased BOLD variability with age and cognitive decline, and others suggesting that increased BOLD fluctuations may serve as a physiological signal reflecting underlying cerebrovascular challenges. Given the paucity of research in this area, the objective of the current study was to investigate BOLD variability as a novel early biomarker of AD and its associated psychophysiological correlates. Method: Neuroimaging and cognitive data were obtained from the Alzheimer's Disease Neuroimaging Initiative (ADNI) 2 database from 19 participants with AD (mean age = 72.7 ± 6.5) and 19 similarly-aged controls (mean age = 74.7 ± 6.9). All analysis steps were performed using tools within the Functional MRI of the Brain Software Library (FSL). For each participant, a map of BOLD signal variability (SDBOLD) was computed as the standard deviation of the BOLD timeseries at each voxel within both grey and white matter regions. Firstly, group comparisons were performed to examine global differences in resting state SDBOLD in AD versus healthy controls. Correlations were then examined between participant SDBOLD maps and (1) ADNI-derived composite scores of memory and executive function and (2) neuroimaging markers of cerebrovascular status (total white matter hyperintensity [WMH] burden, as computed from FLAIR scans). Results: Between-group comparisons revealed significant (p < 0.05) increases in SDBOLD in patients with AD relative to healthy controls in right-lateralized grey and white matter frontal regions, including the superior frontal and precentral gyri, and widespread regions of the corona radiata. Due to the novelty of the current study, secondary analyses investigating the association between SDBOLD and psychophysiological correlates were examined with a more liberal threshold (p < 0.1). Results revealed that lower memory scores were associated with greater SDBOLD in the medial temporal lobe and adjacent structures in the healthy control group. Conversely, higher total WMH burden was associated with greater SDBOLD in highly localized grey and white matter regions in the healthy control group. No association between SDBOLD and cognitive or cerebrovascular measures was identified in the AD group. Conclusion: The current study provides proof of concept that a novel resting state fMRI analysis technique that is non-invasive, easily accessible, and clinically compatible, can differentiate patients with AD from healthy controls. To further explore the potential of SDBOLD as a biomarker of AD, additional studies in larger, longitudinal samples are needed to better understand the changes in SDBOLD that characterize earlier stages of disease progression and their underlying psychophysiological correlates. / Graduate / 2018-08-21

Cognitive deficits are a hallmark feature of both Down Syndrome (DS) and Alzheimer's Disease (AD). Individuals with DS exhibit a very early onset of AD neuropathology, byt heir mid to late 30's. Extra copies of the genes on chromosome 21 may play an important role in this accelerated onset of AD in DS individuals. The amyloid precursor protein (APP) is located on chromosome 21, and among its cleavage products is amyloid-beta (Aß), a component of amyloid plaques. The presence of Aß and amyloid in the brain is a key pathogenic factor, and is considered the central and causative neuropathology in AD by the amyloid cascade hypothesis. Growing evidence suggests an important role for cholesterol in the pathogenesis of AD, particularly in APP metabolism and production of A peptides. The ATP-Binding Cassette-G1 (ABCG1) transporter is located on chromsome 21, and is believed to participate in the maintenance of cholesterol homeostasis. The effects of ABCG1 expression on the production of Aß have proved inconclusive in in vitro studies, demanding an in vivo resolution where appropriate physiology is maintained. To test the hypothesis that overexpression of ABCG1 will accelerate the onset or progression of AD in vivo, we evaluated the cognitive performance of ABCG1-overexpressing mice before and after crossing to the PDAPP mouse model of AD. Both normal and AD mice overexpressing ABCG1 showed no significant deficits on several cognitive tests, including reference and working memory task variations of the Morris Water Maze. Golgi analysis of neuronal structure revealed significantly reduced dendritic complexity in both normal and PDAPP mice overexpressing ABCG1, suggesting that the cholesterol-related functions of ABCG1 have a potentially important role in dendrite development. Interestingly, behavioural analysis of ABCG1-deficient mice revealed a gene-dose dependent trend toward worsened performance on the water maze probe trial, suggesting that the pathways that may compensate for ABCG1 overexpression could be unable to offset a complete deficiency. These experiments suggest an important role for ABCG1 in maintaining cellular cholesterol homeostasis, but do not support the hypothesis that ABCG 1 expression contributes to the accelerated onset of AD pathology in DS individuals. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate

Alzheimer's Disease is characterized by a general decline in cognitive functioning. Although phonology are relatively unaffected, patients with Alzheimer's Disease have been reported to have deficits of semantic memory. Thirteen patients with dementia, five of whom had a confirmed diagnosis of dementia, participated in the study. The purpose of this investigation was to replicate a study performed by Mark Byrd (1984), using Alzheimer's Disease patients. Subjects were presented with category-word decision pairs, for which the task was to decide if the word was an exemplar of the category, and category-letter decision pairs for which the task was to generate an exemplar of the category beginning with the letter. The dependent variable was reaction time. Results indicated that Alzheimer's Disease patients and dementia patients had longer reaction times than a group of age-matched control subjects, and that the Alzheimer's Disease and dementia patients showed a pattern of responses similar to that of the control subjects. All groups showed longer reaction times for the generation trials than the decision trials. The results are consistent with the existence of a semantic memory deficit in Alzheimer's Disease, but other interpretations were discussed. / Medicine, Faculty of / Audiology and Speech Sciences, School of / Graduate

In the present study, the syntactic deficit of Alzheimer's patients was investigated, using an object manipulation task. Four case studies were presented, using data from test batteries devised by Caplan (pers. comm.) and the author. Subjects responded by acting out stimulus sentences presented in aural and written modes, using a set of small figurines. Responses were evaluated following criteria described by Caplan (1986, pers. comm.). Data from the four subjects were compared with each other, and with data obtained from a similar battery administered to aphasic patients. An impairment in the ability to interpret certain syntactic structures was found for all subjects, indicating that Alzheimer's patients do suffer from a syntactic comprehension deficit in the early stages of the disease. Several syntactic structures which caused errors in the responses of the Alzheimer's subjects, also caused errors for the aphasic patients, suggesting that the parsing model underlying the design of the stimuli, described by Caplan (in press) is a valid description of normal language function. Results of the present investigation are examined in relation to a model of syntactic comprehension suggested by Caplan (in press). Contradictions to hypotheses proposed are noted. The limitations and diagnostic use of the object manipulation test, are discussed. / Medicine, Faculty of / Audiology and Speech Sciences, School of / Graduate

Alzheimer's disease is the most common neurodegenerative disease in the elderly. Senile plaques and nerve cells in the fiber entanglement [neurofibrillary tangle (NFT)] are the significant pathological features. Currently, clinical drugs cannot effectively treat AD and reverse its pathogenesis. Therefore, it is of great importance to research and development of new AD therapy drugs. Carbazole-based cyanine is a type of synthetic small molecule compound that shares a common base with different functional groups; for example, SLOH, SLM, and SLCOOH. They exhibited selective binding to Aβ peptides and showed strong inhibition of Aβ peptide aggregation. It was found that one of the cyanines, SLOH, could significantly improve the cognitive ability of 3× Tg-AD mice treated for 40 days from the age of 4 months. In vivo, SLOH reduced Aβ levels and decreased hyperphosphorylation of tau both in the hippocampus and cortex by downregulating the activity of Akt/GSK3β and protein phosphatase 2A, SLOH can also activate the calcium pathway through activating CAMKII and cAMP-response element-binding (CREB). SLM significantly improved cognitive deficits in AD mice both in AD mice aged 4 months and 8 months. Both oligomeric Aβ and phosphorylated tau were decreased, and this was due to the activation of autophagic flux. The other cyanine compound SLCOOH also exhibited significant improvement in the cognitive ability of 4-month 3× Tg-AD mice after two months of treatment. There was significantly reduced Aβ deposition, decreased total tau, and reduced tau hyperphosphorylation by inhibiting the activities of glycogen synthase kinase-3β in 4-month 3× Tg-AD mice. SLCOOH treatment cleared Aβ and tau by upregulating the autophagy pathway, which inhibited the activity of mTOR/p70S6K. Moreover, SLCOOH structurally restored synapses and spines and regulated the Ca2+/CaMKII/CREB signaling pathway, leading to enhanced synaptic plasticity and cognitive ability in AD mice. Furthermore, we found SLCOOH ameliorated synaptic deficits by downregulating N-methyl-D-aspartate receptors (NMDAR), thereby modulating intercellular calcium ion (Ca2+) loading and upregulating neuronal calcium dependent signaling. Thus, our results demonstrated that these three carbazole-based cyanines mitigated cognitive decline by targeting Aβ and tau pathology in 3× Tg-AD mice. Those data strongly support that these three carbazole-based cyanines as a potent therapy for AD.

Alzheimer’s Disease (AD) is a complex brain disorder that affects at least one in every ten persons aged 65 and above worldwide. The pathogenesis of this disorder remains elusive. In this work, we utilized a rich set of publicly available gene expression data to elucidate the genes and molecular processes that may underlie its pathogenesis. We developed a new ranking score to prioritize molecular pathways enriched in differentially expressed genes during AD. After applying our new ranking score, GO categories such as cotranslational protein targeting to membrane, SRP-dependent cotranslational protein targeting to membrane, and spliceosomal snRNP assembly were found to be significantly associated with AD. We also confirm the protein-protein interaction between APP, NPAS4 and ARNT2 and explain that this interaction could be implicated in AD. This interaction could serve as a theoretical framework for further analyses into the role of NPAS4 and other immediate-early genes in AD pathogenesis. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

Alzheimer's disease is the most common neurodegenerative disease in the elderly. Senile plaques and nerve cells in the fiber entanglement [neurofibrillary tangle (NFT)] are the significant pathological features. Currently, clinical drugs cannot effectively treat AD and reverse its pathogenesis. Therefore, it is of great importance to research and development of new AD therapy drugs. Carbazole-based cyanine is a type of synthetic small molecule compound that shares a common base with different functional groups; for example, SLOH, SLM, and SLCOOH. They exhibited selective binding to Aβ peptides and showed strong inhibition of Aβ peptide aggregation. It was found that one of the cyanines, SLOH, could significantly improve the cognitive ability of 3× Tg-AD mice treated for 40 days from the age of 4 months. In vivo, SLOH reduced Aβ levels and decreased hyperphosphorylation of tau both in the hippocampus and cortex by downregulating the activity of Akt/GSK3β and protein phosphatase 2A, SLOH can also activate the calcium pathway through activating CAMKII and cAMP-response element-binding (CREB). SLM significantly improved cognitive deficits in AD mice both in AD mice aged 4 months and 8 months. Both oligomeric Aβ and phosphorylated tau were decreased, and this was due to the activation of autophagic flux. The other cyanine compound SLCOOH also exhibited significant improvement in the cognitive ability of 4-month 3× Tg-AD mice after two months of treatment. There was significantly reduced Aβ deposition, decreased total tau, and reduced tau hyperphosphorylation by inhibiting the activities of glycogen synthase kinase-3β in 4-month 3× Tg-AD mice. SLCOOH treatment cleared Aβ and tau by upregulating the autophagy pathway, which inhibited the activity of mTOR/p70S6K. Moreover, SLCOOH structurally restored synapses and spines and regulated the Ca2+/CaMKII/CREB signaling pathway, leading to enhanced synaptic plasticity and cognitive ability in AD mice. Furthermore, we found SLCOOH ameliorated synaptic deficits by downregulating N-methyl-D-aspartate receptors (NMDAR), thereby modulating intercellular calcium ion (Ca2+) loading and upregulating neuronal calcium dependent signaling. Thus, our results demonstrated that these three carbazole-based cyanines mitigated cognitive decline by targeting Aβ and tau pathology in 3× Tg-AD mice. Those data strongly support that these three carbazole-based cyanines as a potent therapy for AD.

Thesis (Ph.D.)--Boston University / Although motor dysfunction in Parkinson's disease (PD) and memory deficits in Alzheimer's disease (AD) are the respective hallmark symptoms, both neurodegenerative disorders are also associated with significant disruptions in visual functioning. In PD, visuospatial function is impaired, particularly in patients with left-side onset of motor symptoms (LPD), reflecting pathology in right hemisphere brain regions, including the parietal lobe. LPD visuospatial performance is characterized by perceptual distortions, suggesting that lower-level visual processing may contribute to abnormal performance. In AD and PD, reduced contrast sensitivity and other visual difficulties have the potential to impact everyday functioning. The relation of PD visuospatial problems, and AD and PD contrast sensitivity deficits to higher-order impairments is understudied. The present experiments examined visual and visuospatial difficulties in these groups and evaluated an intervention to improve everyday visual function. Experiment I assessed performance on a line bisection task in PD. Participants included non-demented patients (10 LPD, 10 with right-side motor onset [RPD]) and 11 normal control adults (NC). Performance was related to data from measures of retinal structure (Optical Coherence Tomography) and function (Frequency Doubling Technology; FDT) across the eye. Correlations of structure and function were found for all groups. LPD showed predicted downward bisection bias in some sections of the left visual field. Expected rightward bisection bias in LPD was not consistently seen using this presentation method. For RPD, in some sectors, worse FDT sensitivity correlated with upward line bisection bias, as predicted. Experiment II investigated if performance of a complex, familiar visual search task (bingo) could be enhanced in AD and PD by manipulating the visual components of contrast, size, and visual complexity of task stimuli. Participants were 19 younger adults, 14 AD, 17 PD, and 33 NC. Increased stimulus size and decreased complexity improved performance for all groups. Increasing contrast also benefited the AD patients, presumably by compensating for their contrast sensitivity deficit, which was more severe than in the PD and NC groups. The general finding of improved performance across healthy and afflicted groups suggests the value of visual support as an easy-to-apply intervention to enhance cognitive performance.

No description available.

Alzheimer’s disease is a progressive neurodegenerative disorder leading to dementia. Interestingly, AD is more prevalent in women than men, where two third of the diagnosed AD population is female. The underlying neuropathology is characterized by extracellular A𝛽 plaques and intracellular tau tangles leading to neuronal cell death. The hippocampus, the main site for learning and memory exhibits the most significant neuronal loss in AD. It is also one of the primary neurogenic niches in the adult brain. A decline of hippocampal neural stem cells is a common feature of AD indicating a defect in neurogenesis. To model AD neuropathology, a triple transgenic model of AD (3xTg) was used. We hypothesize that the defects associated with adult neurogenesis precede the onset of AD hallmarks. Our data showed that neurogenesis defects are present as early as post-natal day 5 of age in the 3xTg model of AD, well before the development of the neuropathology. The early defects were also observed in the TgCRND8 model of AD at 3 months of age. Moreover, no statistically significant difference was detected between male and female mice at 3 months and 9 months of age when investigating NSC populations. This could indicate that sex may not need to be taken in consideration in research design when investigating NSC decline in 3xTg mice. These findings are of clinical relevance, as they may identify early changes that may open opportunities for therapeutic interventions aiming at preventing or delaying neurodegeneration.