Journal of Alzheimer's Disease - Volume 86, issue 1

Authors: Miron, Justin | Picard, Cynthia | Labonté, Anne | Auld, Daniel | Poirier, Judes | for the PREVENT-AD research group

Article Type: Research Article

Abstract: Background: In mouse models of amyloidosis, macrophage receptor 1 (MSR1) and neprilysin (NEP) have been shown to interact to reduce amyloid burden in the brain. Objective: The purpose of this study is to analyze these two gene products in combination with apolipoproteins and Aβ1-42 in the cerebrospinal fluid (CSF) and plasma of individuals at different stages of Alzheimer’s disease (AD), as well as in autopsied brain samples from ROSMAP (Religious Orders Study and Memory and Aging Project). Methods: CSF/plasma levels of MSR1 and NEP were measured using the sensitive primer extension assay technology. CSF Aβ1-42 …was assessed with ELISA, while CSF ApoE and ApoJ were measured with the Luminex’s multiplex technology. Brain MSR1 , APOE , and CLU (APOJ ) mRNA levels were measured with RNA-Seq and contrasted to amyloid plaques pathology using CERAD staging. Results: While plasma and CSF MSR1 levels are significantly correlated, this correlation was not observed for NEP. In addition to be highly correlated to one another, CSF levels of both MSR1 and NEP are strongly correlated with AD status and CSF Aβ1-42 , ApoE, and ApoJ levels. In the cortical tissues of subjects from ROSMAP, MSR1 mRNA levels are correlated with CLU mRNA levels and the CERAD scores but not with APOE mRNA levels. Conclusion: The discrepancies observed between CSF/plasma levels of MSR1 and NEP with CSF Aβ1-42 and ApoE concentrations can be explained by many factors, such as the disease stage or the involvement of the blood-brain barrier breakdown that leads to the infiltration of peripheral monocytes or macrophages. Show more

Keywords: Alzheimer’s disease, amyloid, biomarkers, inflammation, MSR1, NEP

DOI: 10.3233/JAD-215410

Citation: Journal of Alzheimer's Disease, vol. 86, no. 1, pp. 283-296, 2022

Authors: Zhang, Wei | Zhang, Minghui | Wu, Qin | Shi, Jingshan

Article Type: Research Article

Abstract: Background: Dendrobium nobile Lindl. alkaloids (DNLA) are effective in ameliorating cognitive deficit in SAMP8, AβPP/PS1, and LPS-induced AD animal models, and prevented Aβ-induced synaptic degeneration in cultured hippocampal neurons. However, the underlying mechanisms remain unexplored. Objective: This study investigated the protective effects of DNLA on synaptic damage in an Aβ25-35 -induced rat AD model, in primary cortical neuron cultures, and in PC12 cells transfected with human AβPP695, focusing on the Wnt/β-catenin pathway. Methods: Sprague-Dawley rats received a single Aβ25-35 injection (10μ g) into the bilateral hippocampi. DNLA (40 and 80 mg/kg/d) was intragastrically administrated 7 …days prior to Aβ injection and continued for 28 days. The spatial learning and memory, synaptic morphology, synapse-related proteins, and Wnt signaling components GSK3β and β-catenin phosphorylation were evaluated. Rat primary cortical neuron cultures and AβPP695-PC12 cells were used to evaluate axonal mitochondria distribution, reactive oxygen species production, amyloidogenesis, and Wnt pathway in the protection. Results: DNLA ameliorated Aβ-induced cognitive impairment, increased the number of synapses, elevated the postsynaptic density thickness and expression of synapsin and PSD95 in the hippocampus, and suppressed Aβ-mediated GSK3β activity and the β-catenin phosphorylation. In primary neurons and AβPP695-PC12 cells, DNLA restored Aβ25-35 induced mitochondrial dysfunction and inhibited reactive oxygen species production and amyloidogenesis. Furthermore, the Wnt/β-catenin pathway inhibitor Dkk-1 blocked the effect of DNLA on the expression of Aβ1-42 and PSD95. Conclusion: DNLA rescued Aβ-mediated synaptic and mitochondrial injury and inhibited amyloidogenesis in vivo and in vitro , probably through the activation of Wnt/β-catenin signaling pathway to protect synaptic integrity. Show more

Keywords: Aβ-induced synaptic injury, amyloidogenesis, Dendrobium nobile Lindl. alkaloids, mitochondrial dysfunction, spatial learning and memory, Wnt/β-catenin pathways

DOI: 10.3233/JAD-215433

Citation: Journal of Alzheimer's Disease, vol. 86, no. 1, pp. 297-313, 2022

Authors: Liu, Mingjing | Guo, Shipeng | Huang, Daochao | Hu, Dongjie | Wu, Yili | Zhou, Weihui | Song, Weihong

Article Type: Research Article

Abstract: Background: Chronic alcohol consumption can alter the structure of the central nervous system and disrupt cognitive function. Alcoholics are more likely to develop neurodegenerative disorders such as Alzheimer’s disease (AD) and Parkinson’s disease (PD). However, the role of alcohol in promoting neurotoxicity and neurodegeneration remains unclear. Objective: In this study, we aimed at estimating the effects of chronic binge alcohol exposure on brain transcriptome and behavior changes in a chronic “Drinking in the Dark” (DID) mouse model. Methods: The adult C57BL/6J male mice were exposed to alcohol for 4 weeks. RNA-seq was applied to assess the …effects of chronic alcohol exposure on transcriptome in brain. The open field test and novel object recognition test were used to assess the changes of anxiety level, locomotive function, and short-term memory induced by alcohol. RNA-seq analysis revealed that chronic alcohol exposure caused significant change in the brain transcriptome, especially in prefrontal cortex. Results: The gene dysregulation caused by chronic alcohol exposure includes pathways related to mitochondrial energy metabolism (such as oxidative phosphorylation) and multiple neurodegenerative diseases (such as AD and PD). Furthermore, the pathway and network analyses suggest that the genes involved in mitochondrial energy metabolism, ubiquitin-proteasome system, Wnt signaling pathway, and microtubules may attribute to the neurotoxicity and neurodegeneration caused by chronic alcohol consumption. Additionally, locomotive function was also significantly impaired. Conclusion: This work provides gene transcriptional profile data for future research on alcohol-induced neurodegenerative diseases, especially AD and PD. Show more

Keywords: Brain, chronic alcohol consumption, gene expression, neurodegeneration

DOI: 10.3233/JAD-215508

Citation: Journal of Alzheimer's Disease, vol. 86, no. 1, pp. 315-331, 2022

Authors: Mukaetova-Ladinska, Elizabeta B. | Abdullah, Shahbaz | Critchfield, Mathew | Maltby, John

Article Type: Research Article

Abstract: Background: Memory complaints are frequent among young adults presenting in general practice. Many of them will have reversable, functional cognitive impairment that can easily be mistaken for dementia. Its accurate and timely identification is warranted to prevent further escalation to overt dementia syndrome. Objective: To evaluate the recommended primary care screening cognitive tools for dementia for use in younger people. Methods: 2.5 years clinical data were collected during the course of ongoing patient care for all assessed face-to-face patients in a secondary care memory service for younger adults. Cognitive screening and assessment tests used in primary …[General Practice Assessment of Cognition (GPCOG)] and secondary [Addenbrooke’s Cognitive Examination-III (ACE-III), Rowland Universal Dementia Assessment Scale (RUDAS), Salzburg Dementia Test Prediction (SDTP)] care were analyzed for their accuracy to identify dementia and memory complaints. Area under the curve in receiver operating characteristic curves was used to measure predictive value of tests for a clinical diagnosis of dementia. Results: 348 young adults were assessed for cognitive impairment. Following comprehensive Memory Clinic assessments, 241 (69.25%) were diagnosed with memory complaints in the absence of relevant neuropathology and 107 with dementia. GPCOG, especially the informant part, and RUDAS had low accuracy to identify dementia (AUC = 0.465 and AUC = 0.698, respectively). In contrast, ACE-III and SDTP demonstrated the highest accuracy (AUC = 0.799 and AUC = 0.809/0.817, respectively). Conclusion: Dementia screening in younger people will benefit from SDTP incorporated as part of the screening cognitive toolset. The national guidance on dementia screening tools, diagnostic pathways, and management should also refer to younger adults. Show more

Keywords: Cognitive impairment, cognitive screening, dementia, primary health care, suspected dementia, young adults

DOI: 10.3233/JAD-215514

Citation: Journal of Alzheimer's Disease, vol. 86, no. 1, pp. 333-341, 2022

Authors: Pritchard, Anna Barlach | Fabian, Zsolt | Lawrence, Clare L. | Morton, Glyn | Crean, StJohn | Alder, Jane E.

Article Type: Research Article

Abstract: Background: The effects of the key pathogens and virulence factors associated with gum disease such as Porphyromonas gingivalis (P. gingivalis ) on the central nervous system is of great interest with respect to development of neuropathologies and hence therapeutics and preventative strategies. Chronic infections and associated inflammation are known to weaken the first line of defense for the brain, the blood-brain barrier (BBB). Objective: The focus of this study is to utilize an established human in vitro BBB model to evaluate the effects of P. gingivalis virulence factors lipopolysaccharide (LPS) and outer membrane vesicles (OMVs) on a …primary-derived human model representing the neurovascular unit of the BBB. Methods: Changes to the integrity of the BBB after application of P. gingivalis LPS and OMVs were investigated and correlated with transport of LPS. Additionally, the effect of P. gingivalis LPS and OMVs on human brain microvascular endothelial cells in monolayer was evaluated using immunofluorescence microscopy. Results: The integrity of the BBB model was weakened by application of P. gingivalis LPS and OMVs, as measured by a decrease in electrical resistance and a recovery deficit was seen in comparison to the controls. Application of P. gingivalis OMVs to a monoculture of human brain microvascular endothelial cells showed disruption of the tight junction zona occludens protein (ZO-1) compared to controls. Conclusion: These findings show that the integrity of tight junctions of the human BBB could be weakened by association with P. gingivalis virulence factors LPS and OMVs containing proteolytic enzymes (gingipains). Show more

Keywords: Alzheimer’s disease, blood-brain barrier, human brain microvascular endothelial cells, in vitro BBB model, microbiome, periodontal disease

DOI: 10.3233/JAD-215054

Citation: Journal of Alzheimer's Disease, vol. 86, no. 1, pp. 343-364, 2022

Authors: Eastman, Guillermo | Sharlow, Elizabeth R. | Lazo, John S. | Bloom, George S. | Sotelo-Silveira, José R.

Article Type: Research Article

Abstract: Background: Defining cellular mechanisms that drive Alzheimer’s disease (AD) pathogenesis and progression will be aided by studies defining how gene expression patterns change during pre-symptomatic AD and ensuing periods of declining cognition. Previous studies have emphasized changes in transcriptome, but not translatome regulation, leaving the ultimate results of gene expression alterations relatively unexplored in the context of AD. Objective: To identify genes whose expression might be regulated at the transcriptome and translatome levels in AD, we analyzed gene expression in cerebral cortex of two AD model mouse strains, CVN (APPSwDI ;NOS2 -/- ) and Tg2576 (APPSw ), …and their companion wild type (WT) strains at 6 months of age by tandem RNA-Seq and Ribo-Seq (ribosome profiling). Methods: Identical starting pools of bulk RNA were used for RNA-Seq and Ribo-Seq. Differential gene expression analysis was performed at the transcriptome, translatome, and translational efficiency levels. Regulated genes were functionally evaluated by gene ontology tools. Results: Compared to WT mice, AD model mice had similar levels of transcriptome regulation, but differences in translatome regulation. A microglial signature associated with early stages of Aβ accumulation was upregulated at both levels in CVN mice. Although the two mice strains did not share many regulated genes, they showed common regulated pathways related to AβPP metabolism associated with neurotoxicity and neuroprotection. Conclusion: This work represents the first genome-wide study of brain translatome regulation in animal models of AD and provides evidence of a tight and early translatome regulation of gene expression controlling the balance between neuroprotective and neurodegenerative processes in brain. Show more

Keywords: Alzheimer’s disease, amyloid, microglia, RNA-Seq, mRNA translation, transcriptome regulation

DOI: 10.3233/JAD-215357

Citation: Journal of Alzheimer's Disease, vol. 86, no. 1, pp. 365-386, 2022

Authors: Mesa-Herrera, Fátima | Marín, Raquel | Torrealba, Eduardo | Díaz, Mario

Article Type: Research Article

Abstract: Background: There exists considerable interest in the identification of molecular traits during early stages of Alzheimer’s disease (AD). Mild cognitive impairment (MCI) is considered the closest prodromal stage of AD, and to develop gradually from earlier stages although not always progresses to AD. Classical cerebrospinal fluid (CSF) AD biomarkers, amyloid-β peptides and tau/p-tau proteins, have been measured in prodromal stages yet results are heterogeneous and far from conclusive. Therefore, there exists a pressing need to identify a neurochemical signature for prodromal stages and to predict which cases might progress to AD. Objective: Exploring potential CSF biomarkers related to …brain oxidative and inorganic biochemistry during prodromal stages of the disease. Methods: We have analyzed CSF levels of lipoxidative markers (MDA and 8-isoF2α ), biometals (Cu, Zn, Se, Mn, and Fe), iron-transport protein transferrin (TFER), antioxidant enzymes (SOD and GPx4), detoxifying enzymes (GST and BuChE), as well as classical amyloid-β and total and phosphorylated tau, in cognitively healthy controls, patients with MCI, and subjects exhibiting subjective memory complaints (SMC). Results: Inter-group differences for several variables exhibit differentiable trends along the HC ⟶ SMC ⟶ MCI sequence. More interestingly, the combination of Se, Cu, Zn, SOD, TFER, and GST variables allow differentiable fingerprints for control subjects and each prodromal stage. Further, multivariate scores correlate positively with neurocognitive In-Out test, hence with both episodic memory decline and prediction to dementia. Conclusion: We conclude that changes in the CSF biochemistry related to brain oxidative defense and neurometallomics might provide more powerful and accurate diagnostic tools in preclinical stages of AD. Show more

Keywords: Alzheimer’s disease, butyrylcholinesterase, extracellular superoxide dismutase, glutathione-S-transferase, lipoxidative markers, mild cognitive impairment, neurometalomics, oxidative stress, subjective memory complaints, transferrin

DOI: 10.3233/JAD-215437

Citation: Journal of Alzheimer's Disease, vol. 86, no. 1, pp. 387-402, 2022

Authors: Teixeira, Antonio L. | Salem, Haitham | Martins, Lais B. | Gonzales, Mitzi M. | Seshadri, Sudha | Suchting, Robert

Article Type: Research Article

Abstract: Background: Apathy is among the most frequent neuropsychiatric syndromes in Alzheimer’s disease (AD). Objective: To determine the prevalence of apathy and the associated clinical and laboratorial parameters (focus on inflammatory biomarkers) in patients with dementia enrolled at the Texas Alzheimer’s Research and Care Consortium (TARCC) study. Methods: This is a cross-sectional analysis of TARCC baseline. Participants were evaluated through different clinical tools, including the Mini-Mental State Examination (MMSE) and the Lawton-Brody Instrumental Activities of Daily Life (IADL)/Physical Self-Maintenance Scale (PSMS). Apathy was defined by a positive response to the respective item in the Neuropsychiatric Inventory–Questionnaire applied …to caregivers. Serum levels of 16 biomarkers were determined by HumanMap multiplex immunoassay. Comparisons between apathy versus non-apathy groups were carried out with non-parametric tests. Logistic regression and the least absolute shrinkage and selection operator (LASSO) were used to separately model apathy as a function of each biomarker, adjusted for the potential confounders. Results: From 1,319 patients with AD (M/F: 579/740, mean age ± SD: 75.3 ± 8.4), 373 (28.3%) exhibited apathy. When categorized according to the presence of apathy, the groups had significant differences in sex, diabetes diagnosis, and tobacco use. The apathy group also had worse cognitive performance and daily functioning than the non-apathy group as assessed, respectively, by MMSE and IADL/PSMS. Higher levels of interleukin-6, interleukin-10, and leptin were associated with higher odds of apathy. Conclusion: Apathy is associated with cognitive and functional status in AD. The association between apathy and peripheral inflammatory mediators deserves further investigation. Show more

Keywords: Alzheimer’s disease, apathy, inflammation, interleukin-6, interleukin-10

DOI: 10.3233/JAD-215314

Citation: Journal of Alzheimer's Disease, vol. 86, no. 1, pp. 403-411, 2022

Authors: Reed, Marilyn | Freedman, Morris | Mark Fraser, Amy E. | Bromwich, Matthew | Santiago, Anna Theresa | Gallucci, Christina Elizabeth | Frank, Andrew

Article Type: Research Article

Abstract: Background: Hearing loss is the largest potentially modifiable risk factor for dementia and is highly prevalent among older adults, yet it goes largely unreported, unidentified, and untreated, at great cost to health and quality of life. Hearing screening is a proven cost-effective solution to overcome delays in its identification and management yet is not typically recommended by physicians for older adults. Objective: To demonstrate the feasibility and value of hearing screening for older adults at risk for dementia in order to enhance physicians’ awareness of hearing loss and improve access to timely hearing care. Methods: Patients …referred to two academic medical clinics for memory disorders were offered hearing screening as part of clinic protocol. Patients with hearing loss were recruited to the study if they consented to a post-appointment telephone interview and chart review. Memory Clinic physicians were surveyed about the usefulness of the screening information and referral of patients with hearing loss to audiology. Results: Hearing loss was reliably detected in Memory Clinic patients with both in-office and online screening tools. Physicians reported that screening enhanced their awareness of hearing loss and increased the referral rate to audiology. Conclusion: Hearing screening in Memory Clinic patients is a useful component of clinic protocol that facilitates timely access to management and addresses an important risk factor for dementia. Show more

Keywords: Dementia, hearing loss, memory clinic, older adults, screening

DOI: 10.3233/JAD-215377

Citation: Journal of Alzheimer's Disease, vol. 86, no. 1, pp. 413-424, 2022

Authors: Richter, Nils | David, Lara-Sophia | Grothe, Michel J. | Teipel, Stefan | Dietlein, Markus | Tittgemeyer, Marc | Neumaier, Bernd | Fink, Gereon R. | Onur, Oezguer A. | Kukolja, Juraj

Article Type: Research Article

Abstract: Background: Early and severe neuronal loss in the cholinergic basal forebrain is observed in Alzheimer’s disease (AD). To date, cholinomimetics play a central role in the symptomatic treatment of AD dementia. Although basic research indicates that a cholinergic deficit is present in AD before dementia, the efficacy of cholinomimetics in mild cognitive impairment (MCI) remains controversial. Predictors of cholinergic impairment could guide individualized therapy. Objective: To investigate if the extent of the cholinergic deficit, measured using positron emission tomography (PET) and the tracer 11 C-N-methyl-4-piperidyl acetate (MP4A), could be predicted from the volume of cholinergic basal forebrain nuclei …in non-demented AD patients. Methods: Seventeen patients with a high likelihood of MCI due to AD and 18 age-matched cognitively healthy adults underwent MRI-scanning. Basal forebrain volume was assessed using voxel-based morphometry and a cytoarchitectonic atlas of cholinergic nuclei. Cortical acetylcholinesterase (AChE) activity was measured using MP4A-PET. Results: Cortical AChE activity and nucleus basalis of Meynert (Ch4 area) volume were significantly decreased in MCI. The extent of the cholinergic deficit varied considerably across patients. Greater volumes of anterior basal forebrain nuclei (Ch1/2 area) and younger age (Spearman’s rho (17)   = –0.596, 95% -CI [–0.905, –0.119] and 0.593, 95% -CI [0.092, 0.863])) were associated with a greater cholinergic deficit. Conclusion: Data suggest that less atrophy of the Ch1/2 area and younger age are associated with a more significant cholinergic deficit in MCI due to AD. Further investigations are warranted to determine if the individual response to cholinomimetics can be inferred from these measures. Show more

Keywords: Acetylcholinesterase, aging, MP4A, nucleus basalis of Meynert, positron emission tomography

DOI: 10.3233/JAD-210261

Citation: Journal of Alzheimer's Disease, vol. 86, no. 1, pp. 425-440, 2022