Pages 1-20
Review
Maudlyn O. Etekochay, Amoolya Rao Amaravadhi, Gabriel Villarrubia González, Atanas G. Atanasov, Maima Matin, Mohammad Mofatteh, Harry Wilhelm Steinbusch, Tadele Tesfaye, Domenico Praticò (Handling Associate Editor: Patrizia Mecocci)
Unveiling New Strategies Facilitating the Implementation of Artificial Intelligence in Neuroimaging for the Early Detection of Alzheimer’s Disease
Abstract: Alzheimer's disease (AD) is a chronic neurodegenerative disorder with a global impact. The past few decades have witnessed significant strides in comprehending the underlying pathophysiological mechanisms and developing diagnostic methodologies for AD, such as neuroimaging approaches. Neuroimaging techniques, including positron emission tomography and magnetic resonance imaging, have revolutionized the field by providing valuable insights into the structural and functional alterations in the brains of individuals with AD. These imaging modalities enable the detection of early biomarkers such as amyloid-β plaques and tau protein tangles, facilitating early and precise diagnosis. Furthermore, the emerging technologies encompassing blood-based biomarkers and neurochemical profiling exhibit promising results in the identification of specific molecular signatures for AD. The integration of machine learning algorithms and artificial intelligence has enhanced the predictive capacity of these diagnostic tools when analyzing complex datasets. In this review article, we will highlight not only some of the most used diagnostic imaging approaches in neurodegeneration research but focus much more on new tools like artificial intelligence, emphasizing their application in the realm of AD. These advancements hold immense potential for early detection and intervention, thereby paving the way for personalized therapeutic strategies and ultimately augmenting the quality of life for individuals affected by AD.
Pages 21-40
Review
Mohamad Khaled, Hadi Al-Jamal, Layla Tajer, Reem El-Mir
Alzheimer’s Disease in Lebanon: Exploring Genetic and Environmental Risk Factors—A Comprehensive Review
Abstract: Alzheimer’s disease (AD) is a neurodegenerative condition that displays a high prevalence in Lebanon causing a local burden in healthcare and socio-economic sectors. Unfortunately, the lack of prevalence studies and clinical trials in Lebanon minimizes the improvement of AD patient health status. In this review, we include over 155 articles to cover the different aspects of AD ranging from mechanisms to possible treatment and management tools. We highlight some important modifiable and non-modifiable risk factors of the disease including genetics, age, cardiovascular diseases, smoking, etc. Finally, we propose a hypothetical genetic synergy model between APOE4 and TREM2 genes which constitutes a potential early diagnostic tool that helps in reducing the risk of AD based on preventative measures decades before cognitive decline. The studies on AD in Lebanon and the Middle East are scarce. This review points out the importance of genetic mapping in the understanding of disease pathology which is crucial for the emergence of novel diagnostic tools. Hence, we establish a rigid basis for further research to identify the most influential genetic and environmental risk factors for the purpose of using more specific diagnostic tools and possibly adopting
Pages 41-51
Review
Zheting Zhang, Mervyn Jun Rui Lim (Handling Associate Editor: Saima Hilal)
Incident Dementia After Spontaneous Intracerebral Hemorrhage
Abstract: Post-stroke cognitive impairment and dementia (PSCID) is a complication that affects long-term functional outcomes after stroke. Studies on dementia after long-term follow-up in stroke have focused predominantly on ischemic stroke, which may be different from the development of dementia after spontaneous intracerebral hemorrhage (ICH). In this review, we summarize the existing data and hypotheses on the development of dementia after spontaneous ICH, review the management of post-ICH dementia, and suggest areas for future research. Dementia after spontaneous ICH has a cumulative incidence of up to 32.0–37.4% at 5 years post-ICH. Although the pathophysiology of post-ICH dementia has not been fully understood, two main theoretical frameworks can be considered: 1) the triggering role of ICH (both primary and secondary brain injury) in precipitating cognitive decline and dementia; and 2) the contributory role of pre-existing brain pathology (including small vessel disease and neurodegenerative pathology), reduced cognitive reserve, and genetic factors predisposing to cognitive dysfunction. These pathophysiological pathways may have synergistic effects that converge on dysfunction of the neurovascular unit and disruptions in functional connectivity leading to dementia post-ICH. Management of post-ICH dementia may include screening and monitoring, cognitive therapy, and pharmacotherapy. Non-invasive brain stimulation is an emerging therapeutic modality under investigation for safety and efficacy. Our review highlights that there remains a paucity of data and standardized reporting on incident dementia after spontaneous ICH. Further research is imperative for determining the incidence, risk factors, and pathophysiology of post-ICH dementia, in order to identify new therapies for the treatment of this debilitating condition.
Pages 53-84
Systematic Review
Jie Cai, Danni Xie, Fanjing Kong, Zhenwei Zhai, Zhishan Zhu, Yanru Zhao, Ying Xu, Tao Sun (Handling Associate Editor: Yu-Hui Liu)
Effect and Mechanism of Rapamycin on Cognitive Deficits in Animal Models of Alzheimer’s Disease: A Systematic Review and Meta-analysis of Preclinical Studies
Abstract: Background: Alzheimer’s disease (AD), the most common form of dementia, remains long-term and challenging to diagnose. Furthermore, there is currently no medication to completely cure AD patients. Rapamycin has been clinically demonstrated to postpone the aging process in mice and improve learning and memory abilities in animal models of AD. Therefore, rapamycin has the potential to be significant in the discovery and development of drugs for AD patients. Objective: The main objective of this systematic review and meta-analysis was to investigate the effects and mechanisms of rapamycin on animal models of AD by examining behavioral indicators and pathological features. Methods: Six databases were searched and 4,277 articles were retrieved. In conclusion, 13 studies were included according to predefined criteria. Three authors independently judged the selected literature and methodological quality. Use of subgroup analyses to explore potential mechanistic effects of rapamycin interventions: animal models of AD, specific types of transgenic animal models, dosage, and periodicity of administration. Results: The results of Morris Water Maze (MWM) behavioral test showed that escape latency was shortened by 15.60 seconds with rapamycin therapy, indicating that learning ability was enhanced in AD mice; and the number of traversed platforms was increased by 1.53 times, indicating that the improved memory ability significantly corrected the memory deficits. Conclusions: Rapamycin therapy reduced age-related plaque deposition by decreasing AβPP production and down-regulating β-secretase and γ-secretase activities, furthermore increased amyloid-β clearance by promoting autophagy, as well as reduced tau hyperphosphorylation by up-regulating insulin-degrading enzyme levels.
Pages 85-99
Systematic Review
Coralie Cressot, Agathe Vrillon, Matthieu Lilamand, Hélène Francisque, Aurélie Méauzoone, Claire Hourregue, Julien Dumurgier, Emeline Marlinge, Claire Paquet, Emmanuel Cognat
Psychosis in Neurodegenerative Dementias: A Systematic Comparative Review
Abstract: Background: Psychosis, characterized by delusions and/or hallucinations, is frequently observed during the progression of Alzheimer’s disease (AD) and other neurodegenerative dementias (ND) (i.e., dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD)) and cause diagnostic and management difficulties. Objective: This review aims at presenting a concise and up-to-date overview of psychotic symptoms that occur in patients with ND with a comparative approach. Methods: A systematic review was conducted following the PRISMA guidelines. 98 original studies investigating psychosis phenotypes in neurodegenerative dementias were identified (40 cohort studies, 57 case reports). Results: Psychosis is a frequently observed phenomenon during the course of ND, with reported prevalence ranging from 22.5% to 54.1% in AD, 55.9% to 73.9% in DLB, and 18% to 42% in FTD. Throughout all stages of these diseases, noticeable patterns emerge depending on their underlying causes. Misidentification delusions (16.6-78.3%) and visual hallucinations (50-69.6%) are frequently observed in DLB, while paranoid ideas and somatic preoccupations seem to be particularly common in AD and FTD, respectively (9.1-60.3% and 3.10-41.5%). Limited data were found regarding psychosis in the early stages of these disorders. Conclusions: Literature data suggest that different ND are associated with noticeable variations in psychotic phenotypes, reflecting disease-specific tendencies. Further studies focusing on the early stages of these disorders are necessary to enhance our understanding of early psychotic manifestations associated with ND and help in differential diagnosis issues.
Pages 101-103
Commentary
Christopher B. Morrow, Gregory M. Pontone
Exploring Psychosis in Neurodegenerative Dementia: Connecting Symptoms to Neurobiology
Abstract: The following commentary discusses a review by Cressot et al. entitled: 'Psychosis in Neurodegenerative Dementias: A Systematic Comparative Review'. The authors describe the epidemiology and phenomenology of psychosis across neurodegenerative dementias. Dementia with Lewy bodies had the highest reported prevalence of psychosis at 74% followed by Alzheimer’s disease, 54% and frontotemporal degeneration, 42%. Detailed characterization of psychosis shows differences in the types of hallucinations and delusions by dementia type. These findings suggest that different types of dementia related pathology are associated with high rates of psychosis with more specific symptom profiles than previously appreciated. Understanding the differences and variety of psychotic experiences across dementia types may have diagnostic and therapeutic implications for treating hallucinations and delusions in populations suffering from neurodegenerative diseases.
Pages 105-111
Short Communication
Elise Beckers, Joost M. Riphagen, Maxime Van Egroo, David A. Bennett, Heidi I.L. Jacobs
Sparse Asymmetry in Locus Coeruleus Pathology in Alzheimer’s Disease
Abstract: Tau accumulation in and neurodegeneration of locus coeruleus (LC) neurons is observed in Alzheimer’s disease (AD). We investigated whether tangle and neuronal density in the rostral and caudal LC is characterized by an asymmetric pattern in 77 autopsy cases of the Rush Memory and Aging Project. We found left-right equivalence for tangle density across individuals with and without AD pathology. However, neuronal density, particularly in the caudal-rostral axis of the LC, is asymmetric among individuals with AD pathology. Asymmetry in LC neuronal density may signal advanced disease progression and should be considered in AD neuroimaging studies of LC neurodegeneration.
Pages 113-115
Commentary
Jason Bini
The Importance of PET Imaging to Understanding Whole-Body Cortisol Metabolism in Alzheimer’s Disease
Abstract: Excess cortisol is associated with more severe cognitive decline, Alzheimer’s disease, and related dementia phenotypes. The intracellular enzyme 11β HSD1 regenerates active cortisol from inactive cortisone. In this current issue, high regional brain occupancy of Xanamem™, determined by [11C]TARACT PET imaging of 11β-HSD1, in cognitively normal individuals and mild cognitive impartment/Alzheimer’s disease (AD) patients is presented. In the future, comprehensive kinetic modeling using arterial sampling for occupancy studies, and whole-body PET imaging of 11β HSD1 enzyme levels, in combination with stable isotope studies of cortisol metabolism, can provide broad insight into enzyme levels and activity in AD and other relevant diseases.
Pages 117-120
Commentary
Terence W.H. Chong, Helen Macpherson
Pounding the Pavement: Is the Path to Brain Health Steeper for People Experiencing Greater Socioeconomic Deprivation?
Abstract: Dementia is a global public health priority. Physical activity has myriad health benefits, including for reducing dementia risk. To increase physical activity, detailed understanding of influencing factors is needed. Socioeconomic deprivation affects many aspects of health and wellbeing. Qualitative research with older people experiencing socioeconomic deprivation is needed to explore barriers and enablers to engaging in physical activity, with the view to co-designing interventions for implementation trials. A whole of society approach is pivotal to improving effectiveness of physical activity interventions for older adults with cognitive impairment, and target support for people experiencing socioeconomic deprivation, to improve their health outcomes.
Pages 121-143
Claudia Dorado-Martínez, Enrique Montiel-Flores, Jose Luis Ordoñez-Librado, Ana Luisa Gutierrez-Valdez, Cesar Alfonso Garcia-Caballero, Javier Sanchez-Betancourt, Leonardo Reynoso-Erazo, Rocio Tron-Alvarez, Vianey Rodríguez-Lara, Maria Rosa Avila-Costa (Handling Associate Editor: Lilian Calderón-Garcidueñas)
Histological and Memory Alterations in an Innovative Alzheimer’s Disease Animal Model by Vanadium Pentoxide Inhalation
Abstract: Background: Previous work from our group has shown that chronic exposure to Vanadium pentoxide (V2O5) causes cytoskeletal alterations suggesting that V2O5 can interact with cytoskeletal proteins through polymerization and tyrosine phosphatases inhibition, causing Alzheimer’s disease (AD)-like hippocampal cell death. Objective: This work aims to characterize an innovative AD experimental model through chronic V2O5 inhalation, analyzing the spatial memory alterations and the presence of neurofibrillary tangles (NFTs), amyloid-β (Aβ) senile plaques, cerebral amyloid angiopathy, and dendritic spine loss in AD-related brain structures. Methods: 20 male Wistar rats were divided into control (deionized water) and experimental (0.02 M V2O5 1 h, 3/week for 6 months) groups (n = 10). The T-maze test was used to assess spatial memory once a month. After 6 months, histological alterations of the frontal and entorhinal cortices, CA1, subiculum, and amygdala were analyzed by performing Congo red, Bielschowsky, and Golgi impregnation. Results: Cognitive results in the T-maze showed memory impairment from the third month of V2O5 inhalation. We also noted NFTs, Aβ plaque accumulation in the vascular endothelium and pyramidal neurons, dendritic spine, and neuronal loss in all the analyzed structures, CA1 being the most affected. Conclusions: This model characterizes neurodegenerative changes specific to AD. Our model is compatible with Braak AD stage IV, which represents a moment where it is feasible to propose therapies that have a positive impact on stopping neuronal damage.
Pages 145-159
Han Soo Yoo, Han-Kyeol Kim, Jae-Hoon Lee, Joong-Hyun Chun, Hye Sun Lee, Michel J. Grothe, Stefan Teipel, Enrica Cavedo, Andrea Vergallo, Harald Hampel, Young Hoon Ryu, Hanna Cho, Chul Hyoung Lyoo (Handling Associate Editor: Nils Richter)
Association of Basal Forebrain Volume with Amyloid, Tau, and Cognition in Alzheimer’s Disease
Abstract: Background: Degeneration of cholinergic basal forebrain (BF) neurons characterizes Alzheimer’s disease (AD). However, what role the BF plays in the dynamics of AD pathophysiology has not been investigated precisely. Objective: To investigate the baseline and longitudinal roles of BF along with core neuropathologies in AD. Methods: In this retrospective cohort study, we enrolled 113 subjects (38 amyloid [Aβ]-negative cognitively unimpaired, 6 Aβ-positive cognitively unimpaired, 39 with prodromal AD, and 30 with AD dementia) who performed brain MRI for BF volume and cortical thickness, 18F-florbetaben PET for Aβ, 18F-flortaucipir PET for tau, and detailed cognitive testing longitudinally. We investigated the baseline and longitudinal association of BF volume with Aβ and tau standardized uptake value ratio and cognition. Results: Cross-sectionally, lower BF volume was not independently associated with higher cortical Aβ, but it was associated with tau burden. Tau burden in the orbitofrontal, insular, lateral temporal, inferior temporo-occipital, and anterior cingulate cortices were associated with progressive BF atrophy. Lower BF volume was associated with faster Aβ accumulation, mainly in the prefrontal, anterior temporal, cingulate, and medial occipital cortices. BF volume was associated with progressive decline in language and memory functions regardless of baseline Aβ and tau burden. Conclusions: Tau deposition affected progressive BF atrophy, which in turn accelerated amyloid deposition, leading to a vicious cycle. Also, lower baseline BF volume independently predicted deterioration in cognitive function.
Pages 161-175
Calum Marr, Bethany McDowell, Clive Holmes, Christopher J. Edwards, Christopher Cardwell, Michelle McHenry, Gary Meenagh, Jessica L. Teeling, Bernadette McGuinness
The RESIST Study: Examining Cognitive Change in Rheumatoid Arthritis Patients with Mild Cognitive Impairment Being Treated with a TNF-Inhibitor Compared to a Conventional Synthetic Disease-Modifying Anti-Rheumatic Drug
Abstract: Background: Evidence suggests that TNF inhibitors (TNFi) used to treat rheumatoid arthritis (RA) may protect against Alzheimer’s disease progression by reducing inflammation. Objective: To investigate whether RA patients with mild cognitive impairment (MCI) being treated with a TNFi show slower cognitive decline than those being treated with a conventional synthetic disease-modifying anti-rheumatic drug (csDMARD). Methods: 251 participants with RA and MCI taking either a csDMARD (N = 157) or a TNFi (N = 94) completed cognitive assessments at baseline and 6-month intervals for 18 months. It was hypothesized that those taking TNFis would show less decline on the primary outcome of Free and Cued Selective Reminding Test with Immediate Recall (FCSRT-IR) and the secondary outcome of Montreal Cognitive Assessment (MoCA). Results: No significant changes in FCSRT-IR scores were observed in either treatment group. There was no significant difference in FCSRT-IR between treatment groups at 18 months after adjusting for baseline (mean difference = 0.5, 95% CI = -1.3, 2.3). There was also no difference in MoCA score (mean difference = 0.4, 95% CI = -0.4, 1.3). Conclusions: There was no cognitive decline in participants with MCI being treated with TNFis and csDMARDs, raising the possibility both classes of drug may be protective. Future studies should consider whether controlling inflammatory diseases using any approach is more important than a specific therapeutic intervention.
Pages 177-190
Giovanni Sighinolfi*, Micaela Mitolo*, Fabrizio Pizzagalli, Michelangelo Stanzani-Maserati, Daniel Remondini, Magali Jane Rochat, Elena Cantoni, Greta Venturi, Gianfranco Vornetti, Fiorina Bartiromo, Sabina Capellari, Rocco Liguori, Caterina Tonon, Claudia Testa, Raffaele Lodi *These authors contributed equally to this work.
Sulcal Morphometry Predicts Mild Cognitive Impairment Conversion to Alzheimer’s Disease
Abstract: Background: Being able to differentiate mild cognitive impairment (MCI) patients who would eventually convert (MCIc) to Alzheimer’s disease (AD) from those who would not (MCInc) is a key challenge for prognosis. Objective: This study aimed to investigate the ability of sulcal morphometry to predict MCI progression to AD, dedicating special attention to an accurate identification of sulci. Methods: Twenty-five AD patients, thirty-seven MCI and twenty-five healthy controls (HC) underwent a brain-MR protocol (1.5T scanner) including a high-resolution T1-weighted sequence. MCI patients underwent a neuropsychological assessment at baseline and were clinically re-evaluated after a mean of 2.3 years. At follow-up, 12 MCI were classified as MCInc and 25 as MCIc. Sulcal morphometry was investigated using the BrainVISA framework. Consistency of sulci across subjects was ensured by visual inspection and manual correction of the automatic labelling in each subject. Sulcal surface, depth, length, and width were retrieved from 106 sulci. Features were compared across groups and their classification accuracy in predicting MCI conversion was tested. Potential relationships between sulcal features and cognitive scores were explored using Spearman’s correlation. Results: The width of sulci in the temporo-occipital region strongly differentiated between each pair of groups. Comparing MCIc and MCInc, the width of several sulci in the bilateral temporo-occipital and left frontal areas was significantly altered. Higher width of frontal sulci was associated with worse performances in short-term verbal memory and phonemic fluency. Conclusions: Sulcal morphometry emerged as a strong tool for differentiating HC, MCI, and AD, demonstrating its potential prognostic value for the MCI population.
Pages 191-206
Amir Abbas Tahami Monfared, Artak Khachatryan, Noemi Hummel, Agnieszka Kopiec, Marta Martinez, Raymond Zhang, Quanwu Zhang
Assessing Quality of Life, Economic Burden, and Independence Across the Alzheimer’s Disease Continuum Using Patient-Caregiver Dyad Surveys
Abstract: Background: Alzheimer’s disease (AD) and mild cognitive impairment (MCI) have negative quality of life (QoL) and economic impacts on patients and their caregivers and may increase along the disease continuum from MCI to mild, moderate, and severe AD. Objective: To assess how patient and caregiver QoL, indirect and intangible costs are associated with MCI and AD severity. Methods: An on-line survey of physician-identified patient-caregiver dyads living in the United States was conducted from June–October 2022 and included questions to both patients and their caregivers. Dementia Quality of Life Proxy, the Care-related Quality of Life, Work Productivity and Activity Impairment, and Dependence scale were incorporated into the survey. Regression analyses investigated the association between disease severity and QoL and cost outcomes with adjustment for baseline characteristics. Results: One-hundred patient-caregiver dyads were assessed with the survey (MCI, n=27; mild AD, n=27; moderate AD, n=25; severe AD, n=21). Decreased QoL was found with worsening severity in patients (p<0.01) and in unpaid (informal) caregivers (n=79; p=0.02). Dependence increased with disease severity (p<0.01). Advanced disease severity was associated with higher costs to employers (p=0.04), but not with indirect costs to caregivers. Patient and unpaid caregiver intangible costs increased with disease severity (p<0.01). A significant trend of higher summed costs (indirect costs to caregivers, costs to employers, intangible costs to patients and caregivers) in more severe AD was observed (p<0.01). Conclusions: Patient QoL and functional independence and unpaid caregiver QoL decrease as AD severity increases. Intangible costs to patients and summed costs increase with disease severity and are highest in severe AD.
Pages 207-221
Mohamed Ali Boujelbane, Khaled Trabelsi*, Atef Salem*, Achraf Ammar, Jordan M. Glenn, Omar Boukhrisi, Maha M. AlRashid, Haitham Jahrami, Hamdi Chtourou *These authors contributed equally to this work.
Eye Tracking During Visual Paired-Comparison Tasks: A Systematic Review and Meta-Analysis of the Diagnostic Test Accuracy for Detecting Cognitive Decline
Abstract: Background: Alzheimer's disease and mild cognitive impairment (MCI) progress silently, making early diagnosis challenging, especially in less educated populations. The visual paired comparison (VPC) task, utilizing eye-tracking movement (ETM) technology, offers a promising alternative for early detection of memory decline. Objective: This systematic review and meta-analysis evaluated the efficacy of the VPC task, utilizing ETM as a tool for assessing age-related cognitive changes. Methods: A comprehensive search across five databases and grey literature focused on healthy and impaired memory participants assessed through the ETM-based VPC task. The primary outcomes were novelty preference scores and eye movement metrics. The risk of bias of the included studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). Random-effects meta-analyses calculated Hedges’ g effect size. Sensitivity and specificity of the VPC were meta-analytically pooled. Results: The systematic review included 12 articles, involving 1,022 participants (aged 18 to 90 years, with education ranging from 6.5 to 20.0 years), with a low risk of bias and minimal applicability concerns across all items. Five studies contributed to the meta-analysis, revealing a significant effect favoring the VPC task for recognition memory detection (k = 9, g = -1.03). Pooled sensitivity and specificity analyses demonstrated VPC effectiveness as a recognition memory assessment tool (0.84 and 0.75, respectively). Conclusions: The VPC task, utilizing ETM, may serve as a biomarker for early memory decline detection. Its use as a digital eye-tracking tool presents a possible alternative to traditional tests, warranting further research for application in neurodegenerative disease diagnosis.
Pages 223-240
Yu Yong Choi, Jang Jae Lee, Jan te Nijenhuis, Kyu Yeong Choi, Jongseong Park, Jongmyoung Ok, IL Han Choo, Hoowon Kim, Min-Kyung Song, Seong-Min Choi, Soo Hyun Cho, Youngshik Chae, Byeong C. Kim, Kun Ho Lee
Multi-Ethnic Norms for Volumes of Subcortical and Lobar Brain Structures Measured by Neuro I: Ethnicity May Improve the Diagnosis of Alzheimer’s Disease
Abstract: Background: We previously demonstrated the validity of a regression model that included ethnicity as a novel predictor for predicting normative brain volumes in old age. The model was optimized using brain volumes measured with a standard tool FreeSurfer. Objective: Here we further verified the prediction model using newly estimated brain volumes from Neuro I, a quantitative brain analysis system developed for Korean populations. Methods: Lobar and subcortical volumes were estimated from MRI images of 1,629 normal Korean and 786 Caucasian subjects (age range 59-89) and were predicted in linear regression from ethnicity, age, sex, intracranial volume, magnetic field strength, and scanner manufacturers. Results: In the regression model predicting the new volumes, ethnicity was again a substantial predictor in most regions. Additionally, the model-based z-scores of regions were calculated for 428 AD patients and the matched controls, and then employed for diagnostic classification. When the AD classifier adopted the z-scores adjusted for ethnicity, the diagnostic accuracy has noticeably improved (AUC = 0.85, ΔAUC = +0.04, D = 4.10, p < 0.001). Conclusions: Our results suggest that the prediction model remains robust across different measurement tool, and ethnicity significantly contributes to the establishment of norms for brain volumes and the development of a diagnostic system for neurodegenerative diseases.
Pages 241-250
Ozde Cetinsoy, Ijeoma Anyanwu, Harikrishnan Krishnanand, Gokulakrishnan Natarajan, Naveen Ramachandran, Alan Thomas, Keeley J. Brookes
Gene Association Study of the Urokinase Plasminogen Activator and Its Receptor Gene in Alzheimer’s Disease
Abstract: Background: The role of the innate immune system has long been associated with Alzheimer’s disease (AD). There is now accumulating evidence that the soluble Urokinase Plasminogen Activator Receptor pathway, and its genes, PLAU and PLAUR may be important in AD, and yet there have been few genetic association studies to explore this. Objective: This study utilizes the DNA bank of the Brains for Dementia Research cohort to investigate the genetic association of common polymorphisms across the PLAU and PLAUR genes with AD. Methods: TaqMan genotyping assays were used with standard procedures followed by association analysis in PLINK. Results: No association was observed between the PLAU gene and AD; however, two SNPs located in the PLAUR gene were indicative of a trend towards association but did not surpass multiple testing significance thresholds. Conclusions: Further genotyping studies and exploration of the consequences of these SNPs on gene expression and alternative splicing are warranted to fully uncover the role this system may have in AD.
Pages 251-262
Sang Ngo, Ashley J. Jackson, Madhumitha Manivannan, J. Clayton Young, Brandon Leggins, Noah G. Cryns, Sheila T. Tran, Harli E. Grant, Marguerite V. Knudtson, Winston Chiong
Real World Financial Mismanagement in Alzheimer’s Disease, Frontotemporal Dementia, and Primary Progressive Aphasia
Abstract: Background: Whereas clinical experience in dementia indicates high risk for financial mismanagement, there has been little formal study of real world financial errors in dementia. Objective: We aimed to compare caregiver-reported financial mistakes among people with Alzheimer’s disease, behavioral variant frontotemporal dementia (bvFTD), and primary progressive aphasia (PPA). Methods: Caregivers reported whether participants with dementia had made financial mistakes within the last year; and if so, categorized these as resulting from: (a) being too trusting or gullible, (b) being wasteful or careless with money, or (c) trouble with memory. In a pre-registered analysis (https://archive.org/details/osf-registrations-vupj7-v1), we examined the hypotheses that (1) financial mistakes due to impaired socioemotional function and diminished sensitivity to negative outcomes are more prevalent in bvFTD than in Alzheimer’s disease, and (2) financial mistakes due to memory are more prevalent in Alzheimer’s disease than in bvFTD. Exploratory analyses addressed vulnerability in PPA and brain-behavior relationships using voxel-based morphometry. Results: Concordant with our first hypothesis, bvFTD was more strongly associated than Alzheimer's disease with mistakes due to being too trusting/gullible or wasteful/careless; contrary to our second hypothesis, both groups were similarly likely to make mistakes due to memory. No differences were found between Alzheimer's disease and PPA. Exploratory analyses indicated associations between financial errors and atrophy in right prefrontal and insular cortex. Conclusions: Our findings cohere with documented socioemotional and valuation impairments in bvFTD, and with research indicating comparable memory impairment between bvFTD and Alzheimer's disease.
Pages 263-277
Ganesh Chandrasekaran, Sharon X. Xie, for the Alzheimer’s Disease Neuroimaging Initiative (Handling Associate Editor: Erin Abner)
Improving Regression Analysis with Imputation in a Longitudinal Study of Alzheimer’s Disease
Abstract: Background: Missing data is prevalent in the Alzheimer’s Disease Neuroimaging Initiative (ADNI). It is common to deal with missingness by removing subjects with missing entries prior to statistical analysis; however, this can lead to significant efficiency loss and sometimes bias. It has yet to be demonstrated that the imputation approach to handling this issue can be valuable in some longitudinal regression settings. Objective: The purpose of this study is to demonstrate the importance of imputation and how imputation is correctly done in ADNI by analyzing longitudinal Alzheimer’s Disease Assessment Scale – Cognitive Subscale 13 (ADAS-Cog 13) scores and their association with baseline patient characteristics. Methods: We studied 1,063 subjects in ADNI with mild cognitive impairment. Longitudinal ADAS-Cog 13 scores were modeled with a linear mixed-effects model with baseline clinical and demographic characteristics as predictors. The model estimates obtained without imputation were compared with those obtained after imputation with Multiple Imputation by Chained Equations (MICE). We justify application of MICE by investigating the missing data mechanism and model assumptions. We also assess robustness of the results to the choice of imputation method. Results: The fixed-effects estimates of the linear mixed-effects model after imputation with MICE yield valid, tighter confidence intervals, thus improving the efficiency of the analysis when compared to the analysis done without imputation. Conclusions: Our study demonstrates the importance of accounting for missing data in ADNI. When deciding to perform imputation, care should be taken in choosing the approach, as an invalid one can compromise the statistical analyses.
Pages 279-290
Minjae Kim, Yoo Sung Song, Kyunghwa Han, Yun Jung Bae, Ji Won Han, Ki Woong Kim
Impaired Glymphatic Flow on Diffusion Tensor MRI as a Marker of Neurodegeneration in Alzheimer’s Disease: Correlation with Gray Matter Volume Loss and Cognitive Decline
Abstract: Background: Impaired glymphatic flow on the Alzheimer’s disease (AD) spectrum may be evaluated using diffusion tensor image analysis along the perivascular space (DTI-ALPS). Objective: We aimed to validate impaired glymphatic flow and explore its association with gray matter volume, cognitive status, and cerebral amyloid deposition on the AD spectrum. Methods: 80 participants (mean age, 76.9±8.5 years; 57 women) with AD (n=65) and cognitively normal (CN) (n=15) who underwent 3T brain MRI including DTI and/or amyloid PET were included. After adjusting for age, sex, apolipoprotein E status, and burden of white matter hyperintensities, the ALPS-index was compared according to the AD spectrum. The association between the ALPS-index and gray matter volume, cognitive status, and quantitative amyloid from PET was assessed. Results: The ALPS-index in the AD was significantly lower (mean, 1.476; 95% CI, 1.395–1.556) than in the CN (1.784;1.615–1.952; p=0.026). Volumes of the entorhinal cortex, hippocampus, temporal pole, and primary motor cortex showed significant associations with the ALPS-index (all, p<0.05). There was a positive correlation between the ALPS-index and MMSE score (partial r=0.435; p<0.001), but there was no significant correlation between the ALPS-index and amyloid SUVRs (all, p>0.05). Conclusions: Decreased glymphatic flow measured by DTI-ALPS in AD may serve as a marker of neurodegeneration correlating with structural atrophy and cognitive decline.
Pages 291-305
Yaxuan Wu, Ming Tan, Yanling Gao, Na Geng, Weibin Zhong, Hairong Sun, Zhenguang Li, Chenxi Wu, Xuemei Li, Jinbiao Zhang
Complement Proteins in Serum Astrocyte-Derived Exosomes Are Associated with Poststroke Cognitive Impairment in Type 2 Diabetes Mellitus Patients
Abstract: Background: The complement system plays crucial roles in cognitive impairment and acute ischemic stroke (AIS). High levels of complement proteins in plasma astrocyte-derived exosomes (ADEs) were proven to be associated with Alzheimer's disease. We aimed to investigate the relationship of complement proteins in serum ADEs with poststroke cognitive impairment in type 2 diabetes mellitus (T2DM) patients. Methods: This study analyzed 197 T2DM patients who suffered AIS. The Beijing version of the Montreal Cognitive Assessment (MoCA) was used to assess cognitive function. Complement proteins in serum ADEs were quantified using ELISA kits. Results: Mediation analyses showed that C5b-9 and C3b in serum ADEs partially mediate the impact of obstructive sleep apnea (OSA), depression, small vessel disease (SVD), and infarct volume on cognitive function at the acute phase of AIS in T2DM patients. After adjusting for age, sex, time, and interaction between time and complement proteins in serum ADEs, the mixed linear regression showed that C3b and complement protein Factor B in serum ADEs were associated with MoCA scores at three-, six-, and twelve-months after AIS in T2DM patients. Conclusions: Our study suggested that the impact of OSA, depression, SVD, and infarct volume on cognitive impairment in the acute stage of AIS may partially mediate through the complement proteins in serum ADEs. Additionally, the complement proteins in serum ADEs at the acute phase of AIS associated with MoCA scores at three-, six-, twelve months after AIS in T2DM patients.
Pages 307-319
Tracy Butler, Xiuyuan Wang, Gloria Chiang, Ke Xi, Sumit Niogi, Lidia Glodzik, Yi Li, Qolamreza Ray Razlighi, Liangdong Zhou, Seyed Hani Hojjati, Ilker Ozsahin, Xiangling Mao, Thomas Maloney, Emily Tanzi, Nesrine Rahmouni, Cécile Tissot, Firoza Lussier, Sudhin Shah, Dikoma Shungu, Ajay Gupta, Mony De Leon, P. David Mozley, Tharick Pascoal, Pedro Rosa-Neto
Reduction in Constitutively Activated Auditory Brainstem Microglia in Aging and Alzheimer’s Disease
Abstract: Background: Alzheimer’s disease (AD) pathology is considered to begin in the brainstem, and cerebral microglia are known to play a critical role in AD pathogenesis, yet little is known about brainstem microglia in AD. Translocator protein (TSPO) PET, sensitive to activated microglia, shows high signal in dorsal brainstem in humans, but the precise location and clinical correlates of this signal are unknown. Objective: To define age and AD associations of brainstem TSPO PET signal in humans. Methods: We applied new probabilistic maps of brainstem nuclei to quantify PET-measured TSPO expression over the whole brain including brainstem in 71 subjects (43 controls scanned using 11C-PK11195; 20 controls and 8 AD subjects scanned using 11C-PBR28). We focused on inferior colliculi (IC) because of visually-obvious high signal in this region, and potential relevance to auditory dysfunction in AD. We also assessed bilateral cortex. Results: TSPO expression was normally high in IC and other brainstem regions. IC TSPO was decreased with aging (p=0.001) and in AD subjects versus controls (p=0.004) In cortex, TSPO expression was increased with aging (p=0.030) and AD (p=0.033). Conclusions: Decreased IC TSPO expression with aging and AD—an opposite pattern than in cortex—highlights underappreciated regional heterogeneity in microglia phenotype, and implicates IC in a biological explanation for strong links between hearing loss and AD. Unlike in cerebrum, where TSPO expression is considered pathological, activated microglia in IC and other brainstem nuclei may play a beneficial, homeostatic role. Additional study of brainstem microglia in aging and AD is needed.
Pages 321-332
Kevin Duff, Dustin B. Hammers, Vincent Koppelmans, Jace B. King, John M. Hoffman
Short-Term Practice Effects on Cognitive Tests Across the Late Life Cognitive Spectrum and How They Compare to Biomarkers of Alzheimer’s Disease
Abstract: Background: Practice effects on cognitive testing in mild cognitive impairment (MCI) and Alzheimer’s disease (AD) remain understudied, especially with how they compare to biomarkers of AD. Objective: The current study sought to add to this growing literature. Methods: Cognitively intact older adults (n=68), those with amnestic MCI (n=52), and those with mild AD (n=45) completed a brief battery of cognitive tests at baseline and again after one week, and they also completed a baseline amyloid PET scan, a baseline MRI, and a baseline blood draw to obtain APOE ε4 status. Results: The intact participants showed significantly larger baseline cognitive scores and practice effects than the other two groups on overall composite measures. Those with MCI showed significantly larger baseline scores and practice effects than AD participants on the composite. For amyloid deposition, the intact participants had significantly less tracer uptake, whereas MCI and AD participants were comparable. For total hippocampal volumes, all three groups were significantly different in the expected direction (intact>MCI>AD). For APOE ε4, the intact had significantly fewer copies of ε4 than MCI and AD. The effect sizes of the baseline cognitive scores and practice effects were comparable, and they were significantly larger than effect sizes of biomarkers in 7 of the 9 comparisons. Conclusions: Baseline cognition and short-term practice effects appear to be sensitive markers in late life cognitive disorders, as they separated groups better than commonly-used biomarkers in AD. Further development of baseline cognition and short-term practice effects as tools for clinical diagnosis, prognostic indication, and enrichment of clinical trials seems warranted.
Pages 333-343
Mohammed Alrouji, Sabina Yasmin, Mohammad Furkan, Fahad A. Alhumaydhi, Sharaf E. Sharaf, Rizwan Hasan Khan, Anas Shamsi (Handling Associate Editor: Rekha Khandia)
Unveiling the Molecular Interactions Between Human Transferrin and Limonene: Natural Compounds in Alzheimer’s Disease Therapeutics
Abstract: Background: Neurodegeneration is a term describing an irreversible process of neuronal damage. In recent decades, research efforts have been directed towards deepening our knowledge of numerous neurodegenerative disorders, with a particular focus on conditions such as Alzheimer's disease (AD). Human transferrin (htf) is a key player in maintaining iron homeostasis within brain cells. Any disturbance in this equilibrium gives rise to the emergence of neurodegenerative diseases and associated pathologies, particularly AD. Limonene, a natural compound found in citrus fruits and various plants, has shown potential neuroprotective properties. Objective: In this study, our goal was to unravel the binding of limonene with htf, with the intention of comprehending the interaction mechanism of limonene with htf. Methods: Binding was scrutinized using fluorescence quenching and UV-Vis spectroscopic analyses. The binding mechanism of limonene was further investigated at the atomic level through molecular docking and extensive 200 ns molecular dynamic simulation (MD) studies. Results: Molecular docking uncovered that limonene interacted extensively with the deep cavity located within the htf binding pocket. MD results indicated that binding of limonene to htf did not induce substantial structural alterations, ultimately forming stable complex. The findings from fluorescence binding indicated a pronounced interaction between limonene and htf, limonene binds to htf with a binding constant (K) of 0.1 X 105 M-1. UV spectroscopy also advocated stable htf-limonene complex formation. Conclusions: The study deciphered the binding mechanism of limonene with htf, providing a platform to use limonene in AD therapeutics in context of iron homeostasis.
Pages 345-362
Donghyun Kim, Parivash Jamrasi, Xinxing Li, Soyoung Ahn, Yunho Sung, Seohyun Ahn, Yuseon Kang, Wook Song
Effects of Exercise on Urinary AD7c-NTP (Alzheimer-Associated Neuronal Thread Protein) Levels and Cognitive Function Among Active Korean Elderly: A Randomized Controlled Trial
Abstract: Background: Alzheimer-associated neuronal thread protein (AD7c-NTP) has been demonstrated to have high diagnostic accuracy in differentiating Alzheimer’s disease (AD) patients with healthy individuals. However, it is yet unclear whether exercise can lower the level of AD7c-NTP in urine among active Korean elderly. Objective: To assess the effect of exercise on AD7c-ntp levels in urine and cognitive function among active Korean elderly. Methods: In total, 40 Korean elderly (≥ 65 years) were divided into Active Control group (CG, n=10), Aerobic exercise group (AG, n=18), and combined Resistance/Aerobic exercise group (RAG, n=12). A total of 12 weeks of exercise intervention was implemented. At week 0 and 12, cognitive performance (Korean Mini-Mental State Examination, Korean-Color Word Stroop test), grip strength, and body composition (muscle mass and body fat percentage) were measured. Also, a morning urine sample was obtained from each subject. The level of AD7c-NTP was measured using competitive enzyme-linked immunosorbent assay (ELISA). Results: After 12 weeks of exercise intervention, there was a significant difference of AD7c-NTP levels between RAG and CG (p=0.026), AG and CG (p=0.032), respectively. Furthermore, the AD7c-NTP levels in urine showed negative correlation with K-MMSE scores (r=-0.390, p=0.013) and grip strength (r=-0.376, p=0.017), in all participants after exercise intervention. Conclusions: This is the first study to investigate urine biomarker through exercise intervention. In future study, participants who have low cognitive function and low activity levels need to be recruited to observe more significant ‘Exercise’ effect.
Pages 363-375
Linda Gjøra, Bjørn Heine Strand, Sverre Bergh, Ingunn Bosnes,, Aud Johannessen, Gill Livingston, Håvard Kjesbu Skjellegrind, Geir Selbæk
Prevalence and Determinants of Diagnosed Dementia in Primary Care and Hospitals in Norway: The HUNT Study
Abstract: Background: A timely diagnosis of dementia can be beneficial for providing good support, treatment, and care, but the diagnostic rate remains unknown and is probably low. Objective: To determine the dementia diagnostic rate and to describe factors associated with diagnosed dementia. Methods: This project linked information on research-based diagnoses of all-cause dementia and subtypes of dementias, Alzheimer’s disease and related dementias, from a cross-sectional population-based study (HUNT4 70+) to dementia diagnoses recorded in both primary-care and hospital registries. Results: Among those with research-based dementia diagnoses in HUNT4 70+, 35.6% had a dementia diagnosis recorded in the health registries. The diagnostic rate was 19.8% among home-dwellers and 66.0% among nursing home residents. Factors associated with having a registered diagnosis included dementia in the family, not being in the youngest or oldest age group, higher education, more severe cognitive decline, and a greater need for help with activities of daily living. Conclusions: Undiagnosed dementia is common, as only one-third of those with dementia are diagnosed. Diagnoses appear to be made at a late stage of dementia.
Pages 377-392
Vanessa J. Lissek, Stefan Orth, Boris Suchan
go4cognition: Evaluation of a Newly Developed Multicomponent Intervention in Mild Cognitive Impairment
Abstract: Background: Cognitive training and physical exercise show positive effects on cognitive decline in subjects with mild cognitive impairment (MCI). Multimodal interventions for MCI patients, combining physical and cognitive training in a social context seem to slow down cognitive decline. Objective: Based on a previous study, a new mobile gamification tool (go4cognition; https://www.ontaris.de/go4cognition) has been developed to train cognitive and physical functions simultaneously in a group setting. It involves tasks targeting various cognitive functions (short-term memory, working memory, executive functions). The computer-based setup allows for individual performance analysis. This study evaluated the effects of this tool. Methods: 30 participants with MCI, as defined by the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) cut-off-score, aged between 66 and 89 years, trained for one hour two days a week for twelve weeks. Additionally, standard neuropsychological assessment of memory and attention was carried out before and after the intervention. Results: The go4cognition device is highly effective in improving various cognitive functions. A significant improvement in the CERAD total score resulting in re-classification of 70% of former MCI patients into non-MCI patients was found. Additionally, an improvement of verbal fluency, verbal memory, spatial memory, and attention was observed. Furthermore, the CERAD total score was significantly correlated with performance in the go4cognition tool. Conclusions: The results of the intervention support the idea of the effectiveness of a combined cognitive and motor intervention by incorporating neuropsychological paradigms in a group setting and suggest a close relation between combined cognitive and physical exercise and cognitive performance.
Pages 393-402
Lang Peng*, Qingwei Xiang*, Yong Zhou*, Renyi Yin *These authors contributed equally to this work.
Associations of Handgrip Strength Weakness and Asymmetry with Lower Cognitive Function: Results from the National Health and Nutrition Examination Survey (2011–2014)
Abstract: Background: The joint associations of handgrip strength (HGS) weakness and asymmetry with cognitive decline remain understudied in older adults. Objective: To investigate the associations between HGS weakness, asymmetry, and lower cognitive function in a nationally representative sample of older Americans. Methods: This cross-sectional study utilized data from the National Health and Nutrition Examination Survey 2011-2014. Weakness was defined as HGS <26 kg for men and <16 kg for women. Asymmetry was determined by calculating the ratio of dominant to non-dominant HGS. Participants with an HGS ratio <0.90 or >1.10 were classified as having any HGS asymmetry. Those with an HGS ratio >1.10 exhibited dominant HGS asymmetry, while those with an HGS ratio <0.90 displayed nondominant HGS asymmetry, respectively. Lower cognitive functioning was defined as global cognitive composite scores more than 1 standard deviation below the mean. Covariate-adjusted logistic regression models were used to analyze the associations between HGS asymmetry/weakness and lower cognitive functioning. Results: Compared to individuals with non-weak and symmetric HGS, those with any HGS asymmetry alone and weakness alone had 1.017 (95% confidence interval [CI]: 0.707-1.463) and 1.391 (95%CI: 0.542-3.571) greater odds for cognitive decline, while co-occurrence of both HGS asymmetry and weakness was associated with 3.724 (95%CI: 1.711-8.107) greater odds for lower cognitive function after controlling for confounders. Conclusions: Individuals exhibiting both diminished and asymmetrical HGS demonstrated an elevated susceptibility to cognitive impairment, thereby implying that the inclusion of HGS asymmetry assessment in conjunction with weakness evaluation may enhance the accuracy of prognosticating cognitive decline.
Pages 403-415
Miharu Nakanishi, Syudo Yamasaki, Taeko Nakashima, Yuki Miyamoto, Claudia Cooper, Marcus Richards, Daniel Stanyon, Mai Sakai, Hatsumi Yoshii, Atsushi Nishida (Handling Associate Editor: Kaarin Anstey)
Association Between Dementia, Change in Home-Care Use, and Depressive Symptoms During the COVID-19 Pandemic: A Longitudinal Study Using Data from Three Cohort Studies
Abstract: Background: The emotional impact of the coronavirus disease 2019 (COVID-19) pandemic on people with dementia has been quantified. However, little is known about the impact of change in home-care use owing to the pandemic. Objective: To determine the longitudinal association between dementia, change in home-care use, and depressive symptoms during the pandemic. Methods: We included data of 43,782 home-dwelling older adults from the English Longitudinal Study of Ageing (ELSA), Study of health, Ageing and Retirement in Europe (SHARE), and National Health and Aging Trends Study (NHATS). This study considered the latest main wave survey prior to the pandemic as the baseline, and the COVID-19 survey as follow-up. In a series of coordinated analyses, multilevel binomial logistic regression model was used to examine the association between baseline dementia, change in home-care use at follow-up, and presence of depressive symptoms. Results: Dementia, using the ELSA, SHARE, and NHATS datasets, was identified in 2.9%, 2.3%, and 6.5% of older adults, and home-care use reduced in 1.7%, 2.8%, and 1.1% of individuals with dementia, respectively. Dementia was significantly associated with the increased risk of depressive symptoms in all three cohorts. However, the interaction between dementia and period (follow-up) was non-significant in SHARE and NHATS. Across all three cohorts, home-care use during the pandemic, regardless of change in amount, was significantly associated with increased depressive symptoms, compared to the non-use of home care. Conclusions: These results highlight the need for tailoring dementia care at home to promote independence and provide sustainable emotional support.
Pages 417-427
Kelsey R. Thomas, Alexandra L. Clark, Alexandra J. Weigand, Lauren Edwards, Alin Alshaheri Durazo, Rachel Membreno, Britney Luu, Peter Rantins, Monica T. Ly, Lindsay J. Rotblatt, Katherine J. Bangen, Amy J. Jak for the Department of Defense Alzheimer’s Disease Neuroimaging Initiative (Handling Associate Editor: David Loewenstein)
Cognition and Amyloid-β in Older Veterans: Characterization and Longitudinal Outcomes of Data-Derived Phenotypes
Abstract: Background: Within older Veterans, multiple factors may contribute to cognitive difficulties. Beyond Alzheimer’s disease (AD), psychiatric (e.g., PTSD) and health comorbidities (e.g., TBI) may also impact cognition. Objective: This study aimed to derive subgroups based on objective cognition, subjective cognitive decline (SCD), and amyloid burden, and then compare subgroups on clinical characteristics, biomarkers, and longitudinal change in functioning and global cognition. Methods: Cluster analysis of neuropsychological measures, SCD, and amyloid PET was conducted on 228 predominately male Vietnam-Era Veterans from the Department of Defense-Alzheimer’s Disease Neuroimaging Initiative. Cluster-derived subgroups were compared on baseline characteristics as well as 1-year changes in everyday functioning and global cognition. Results: The cluster analysis identified 3 groups. Group 1 (n=128) had average-to-above average cognition with low amyloid burden. Group 2 (n=72) had the lowest memory and language, highest SCD, and average amyloid burden; they also had the most severe PTSD, pain, and worst sleep quality. Group 3 (n=28) had the lowest attention/executive functioning, slightly low memory and language, elevated amyloid and the worst AD biomarkers, and the fastest rate of everyday functioning and cognitive decline. Conclusions: Psychiatric and health factors likely contributed to Group 2’s low memory and language performance. Group 3 was most consistent with biological AD, yet attention/executive function was the lowest score. The complexity of older Veterans’ co-morbid conditions may interact with AD pathology to show attention/executive dysfunction (rather than memory) as a prominent early symptom. These results could have important implications for the implementation of AD-modifying drugs in older Veterans.
