Duygu Gezen-Ak, Erdinc Dursun
Vitamin D, a Secosteroid Hormone and Its Multifunctional Receptor, Vitamin D Receptor, in Alzheimer’s Type Neurodegeneration
Abstract: Vitamin D is a secosteroid hormone exerting neurosteroid-like properties. Its well-known nuclear hormone receptor, and recently proposed as a mitochondrial transcription factor, vitamin D receptor, acts for its primary functions. The second receptor is an endoplasmic reticulum protein, protein disulfide isomerase A3 (PDIA3), suggested to act as a rapid response. Vitamin D has effects on various systems, particularly through calcium metabolism. Among them, the nervous system has an important place in the context of our subject. Recent studies have shown that vitamin D and its receptors have numerous effects on the nervous system. Neurodegeneration is a long-term process. Throughout a human life span, so is vitamin D deficiency. Our previous studies and others have suggested that the out-come of long-term vitamin D deficiency (hypovitaminosis D or inefficient utilization of vitamin D), may lead neurons to be vulnerable to aging and neurodegeneration. We suggest that keeping vitamin D levels at adequate levels at all stages of life, considering new approaches such as agonists that can activate vitamin D receptors, and utilizing other derivatives produced in the synthesis process with UVB are crucial when considering vitamin D-based intervention studies. Given most aspects of vitamin D, this review outlines how vitamin D and its receptors work and are involved in neurodegeneration, emphasizing Alzheimer’s disease.
Suzanne M. de la Monte
Malignant Brain Aging: The Formidable Link Between Dysregulated Signaling Through Mechanistic Target of Rapamycin Pathways and Alzheimer’s Disease (Type 3 Diabetes)
Abstract: Malignant brain aging corresponds to accelerated age-related declines in brain functions eventually derailing the self-sustaining forces that govern independent vitality. Malignant brain aging establishes the path toward dementing neurodegeneration, including Alzheimer’s disease (AD). The full spectrum of AD includes progressive dysfunction of neurons, oligodendrocytes, astrocytes, microglia, and the microvascular systems, and is mechanistically driven by insulin and insulin-like growth factor (IGF) deficiencies and resistances with accompanying deficits in energy balance, increased cellular stress, inflammation, and impaired perfusion, mimicking the core features of diabetes mellitus. The underlying pathophysiological derangements result in mitochondrial dysfunction, abnormal protein aggregation, increased oxidative and endoplasmic reticulum stress, aberrant autophagy, and abnormal post-translational modification of proteins, all of which are signature features of both AD and dysregulated insulin/IGF-1-mechanistic target of rapamycin (mTOR) signaling. This article connects the dots from benign to malignant aging to neurodegeneration by reviewing the salient pathologies associated with initially adaptive and later dysfunctional mTOR signaling in the brain. Effective therapeutic and preventive measures must be two-pronged and designed to 1) address complex and shifting impairments in mTOR signaling through the re-purpose of effective anti-diabetes therapeutics that target the brain, and 2) minimize the impact of extrinsic mediators of benign to malignant aging transitions, e.g., inflammatory states, obesity, systemic insulin resistance diseases, and repeated bouts of general anesthesia, by minimizing exposures or implementing neuroprotective measures.
Boluwatife Adeleye Adewale, Motunrayo Mojoyin Coker, Adesola Ogunniyi, Rajesh N. Kalaria, Rufus Olusola Akinyemi
Biomarkers and Risk Assessment of Alzheimer's Disease in Low- and Middle-Income Countries
Abstract: Dementia is a chronic syndrome which is common among the elderly and is associated with significant morbidity and mortality for patients and their caregivers. Alzheimer's disease (AD), the most common form of clinical dementia, is biologically characterized by the deposition of amyloid-β plaques and neurofibrillary tangles in the brain. The onset of AD begins decades before manifestation of symptoms and clinical diagnosis, underlining the need to shift from clinical diagnosis of AD to a more objective diagnosis using biomarkers. Having performed a literature search of original articles and reviews on PubMed and Google Scholar, we present this review detailing the existing biomarkers and risk assessment tools for AD. The prevalence of dementia in low- and middle-income countries (LMICs) is predicted to increase over the next couple of years. Thus, we aimed to identify potential biomarkers that may be appropriate for use in LMICs, considering the following factors: sensitivity, specificity, invasiveness, and affordability of the biomarkers. We also explored risk assessment tools and the potential use of artificial intelligence/machine learning solutions for diagnosing, assessing risks, and monitoring the progression of AD in low-resource settings. Routine use of AD biomarkers has yet to gain sufficient ground in clinical settings. Therefore, clinical diagnosis of AD will remain the mainstay in LMICs for the foreseeable future. Efforts should be made towards the development of low-cost, easily administered risk assessment tools to identify individuals who are at risk of AD in the population. We recommend that stakeholders invest in education, research and development targeted towards effective risk assessment and management.
Ilsa R. Wojt, Edward C.Y. Lau, Rose Cairns, Edwin C.K. Tan
Poisonings in Older People with Dementia: A Systematic Scoping Review and Meta-Analysis
Abstract: Background: Older people with dementia are at a particularly high risk of poisonings and their subsequent harms. Objective: This review aimed to describe the key agents, incidence, risk factors, and disposition of poisonings in people with dementia reported in the literature. Methods: Medline, Embase, CINAHL, and PsycINFO databases were searched from 1 September 2001 to 1 September 2021. Terms for dementia, poisonings, and older adults formed the search concepts. Quantitative studies published in English, describing poisonings in older people with dementia, including Alzheimer’s disease, were included. Two investigators independently assessed articles for eligibility and extracted relevant data. A meta-analysis of the incidence of poisonings in people with dementia across studies was performed. Results: Of 4,579 articles, 18 were included for final synthesis. Nervous system medications were implicated in over half of all medicinal poisonings, with anti-dementia agents, benzodiazepines, and opioids the most common classes. The non-medicinal agents frequently associated with poisonings were personal care and household products. The yearly incidence of poisoning varied across definitions of poisoning from 3% for International Classification of Disease-defined poisonings to 43% for adverse drug event-defined poisonings. Several risk factors were identified, including multimorbidity, psychotropic medication use, and living in residential care. Where described, up to one in five poisonings resulted in hospitalisation and in death. Conclusions: Poisonings are common in people with dementia, involving commonly prescribed medications or easily accessible substances. Given the significant outcomes associated, further research is required to better understand these poisonings and improve public health strategies to reduce the occurrence of this preventable harm.
Donald J. Lehmann, Amany Elshorbagy, Michael J. Hurley
Many Paths to Alzheimer’s Disease: A Unifying Hypothesis Integrating Biological, Chemical, and Physical Risk Factors
Abstract: Sporadic Alzheimer’s disease (AD) is a complex, multifactorial disease. We should therefore expect to find many factors involved in its causation. The known neuropathology seen at autopsy in patients dying with AD is not consistently seen in all patients with AD and is sometimes seen in patients without dementia. This suggests that patients follow different paths to AD, with different people having slightly different combinations of predisposing physical, chemical and biologic risk factors, and varying neuropathology. This review summarizes what is known of the biologic and chemical predisposing factors and features in AD. We postulate that, underlying the neuropathology of AD is a progressive failure of neurons, with advancing age or other morbidity, to rid themselves of entropy, i.e., the disordered state resulting from brain metabolism. Understanding the diverse causes of AD may allow the development of new therapies targeted at blocking the paths that lead to dementia in each subset of patients.
Federico Verde*, Edoardo Nicolò Aiello*, Laura Adobbati, Barbara Poletti, Federica Solca, Cinzia Tiloca, Davide Sangalli, Alessio Maranzano, Cristina Muscio, Antonia Ratti, Stefano Zago, Nicola Ticozzi, Giovanni Battista Frisoni, Vincenzo Silani (Handling Associate Editor: Carlo Abbate) *These authors contributed equally to this work.
Coexistence of Amyotrophic Lateral Sclerosis and Alzheimer’s Disease: Case Report and Review of the Literature
Abstract: We describe a case of amyotrophic lateral sclerosis (ALS) associated with Alzheimer’s disease (AD) and review the literature about the coexistence of the two entities, highlighting the following: mean age at onset is 63.8 years, with slight female predominance; ALS tends to manifest after cognitive impairment and often begins in the bulbar region; average disease duration is 3 years; cognitive phenotype is mostly amnestic; the pattern of brain involvement is, in most cases, consistent with AD. Our case and the reviewed ones suggest that patients with ALS and dementia lacking unequivocal features of FTD should undergo additional examinations in order to recognize AD.
Lorenzo Barba, Markus Otto, Samir Abu-Rumeileh
The Underestimated Relevance of Alzheimer’s Disease Copathology in Amyotrophic Lateral Sclerosis
Abstract: Concomitant Alzheimer’s disease (AD) pathology can be observed in approximately 10-15% of cases with amyotrophic lateral sclerosis (ALS). ALS-AD patients have a higher prevalence of amnestic cognitive disturbances, which may often precede motor symptoms. Cerebrospinal fluid (CSF) AD core biomarkers usually show no or slightly significant changes in ALS, whereas blood phosphorylated tau protein might be increased independently from AD copathology. Neurofilament proteins are consistently elevated in CSF and blood of ALS, but have been poorly investigated in ALS-AD. All these issues should be taken into account when using fluid biomarkers as inclusion criteria or secondary endpoints in clinical trials.
Priscilla A. Amofa-Ho*, Ariana M. Stickel*, Ruijia Chen, Lindsay C. Kobayashi, M. Maria Glymour, Chloe W. Eng for the Alzheimer's Disease Neuroimaging Initiative (Handling Associate Editor: Lilian Calderón-Garcidueñas) *These authors contributed equally to this work.
The Mediating Roles of Neurobiomarkers in the Relationship Between Education and Late-Life Cognition
Abstract: Background: The mediating roles of neuropathologies and neurovascular damage in the relationship between early-life education and later-life cognitive function are unknown. Objective: To examine whether Alzheimer’s and neurovascular biomarkers mediate the relationships between education and cognitive functions. Methods: Data were from 537 adults aged 55-94 in the Alzheimer’s Disease Neuroimaging Initiative 3. We tested whether the relationships between education (continuous, years) and cognitive function (memory, executive functioning, and language composites) were mediated by neuroimaging biomarkers (hippocampal volumes, cortical gray matter volumes, meta-temporal tau PET standard uptake value ratio, and white matter hyperintensity volumes). Models were adjusted for age, race, sex/gender, cardiovascular history, body mass index, depression, and Apolipoprotein E-ε4 status. Results: Hippocampal volumes and white matter hyperintensities partially mediated the relationships between education and cognitive function across all domains (6.43% to 15.72% mediated). The direct effects of education on each cognitive domain were strong and statistically significant. Conclusions: Commonly measured neurobiomarkers only partially mediate the relationships between education and multi-domain cognitive function.
Puja Agarwal, Christopher N. Ford, Sue E. Leurgans, Todd Beck, Pankaja Desai, Klodian Dhana, Denis A. Evans, Shannon Halloway, Thomas M. Holland, Kristin R. Krueger, Xiaoran Liu, Kumar Bharat Rajan, David A. Bennett (Handling Associate Editor: Shuang Rong)
Dietary Sugar Intake Associated with a Higher Risk of Dementia in Community-Dwelling Older Adults
Abstract: Background: We have limited evidence for the relationship of high sugar intake with dementia risk. Objective: To determine whether high sugar intake is associated with an increased risk of dementia in community-dwelling older adults Methods: This study included 789 participants of the Rush Memory and Aging Project (community-based longitudinal cohort study of older adults free of known dementia at enrollment), with annual clinical assessments and complete nutrient data (obtained by validated food frequency questionnaire). Clinical diagnosis of dementia is based on the criteria of the joint working group of the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer’s Disease and Related Disorders Association. We used Cox proportional hazard models. Results: 118 participants developed dementia during 7.3±3.8 years of follow-up. Those in the highest quintile of total sugar intake were twice as likely to develop dementia than those in the lowest quintile (Q5 versus Q1:HR=2.10 (95%CI: 1.05, 4.19) when adjusted for age, sex, education, APOE ε4 allele, calories from sources other than sugar, physical activity, and diet score. Higher percent calories from sugar were positively associated with dementia risk (β=0.042, p=0.0009). In exploratory analyses, the highest versus lowest quintile of fructose and sucrose in the diet had higher dementia risk by 2.8 (95%CI: 1.38, 5.67) and 1.93 (95%CI: 1.05, 3.54) times, respectively. Conclusions: A higher intake of total sugar or total calories from sugar is associated with increased dementia risk in older adults. Among simple sugars, fructose (e.g., sweetened beverages, snacks, packaged desserts) and sucrose (table sugar in juices, desserts, candies, and commercial cereals) are associated with higher dementia risk.
Sofia Marcolini, Philine Rojczyk, Johanna Seitz-Holland, Inga K. Koerte, Michael L. Alosco, Sylvain Bouix, for the Department of Defense Alzheimer’s Disease Neuroimaging Initiative
Posttraumatic Stress and Traumatic Brain Injury: Cognition, Behavior, and Neuroimaging Markers in Vietnam Veterans
Abstract: Background: Posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI) are common in Veterans and linked to behavioral disturbances, increased risk of cognitive decline, and Alzheimer’s disease. Objective: We studied the synergistic effects of PTSD and TBI on behavioral, cognitive, and neuroimaging measures in Vietnam war Veterans. Methods: Data were acquired at baseline and after about one-year from male Veterans categorized into: PTSD, TBI, PTSD+TBI, and Veteran controls without PTSD or TBI. We applied manual tractography to examine white matter microstructure of three fiber tracts: uncinate fasciculus (N=91), cingulum (N=87), and inferior longitudinal fasciculus (N=95). ANCOVAs were used to compare Veterans’ baseline behavioral and cognitive functioning (N=285), white matter microstructure, amyloid-β (N=230), and tau PET (N=120). Additional ANCOVAs examined scores’ differences from baseline to follow-up. Results: Veterans with PTSD and PTSD+TBI, but not Veterans with TBI only, exhibited poorer behavioral and cognitive functioning at baseline than controls. The groups did not differ in baseline white matter, amyloid-β, or tau, nor in behavioral and cognitive functioning, and tau accumulation change. Progression of white matter abnormalities of the uncinate fasciculus in Veterans with PTSD compared to controls was observed; analyses in TBI and PTSD+TBI were not run due to insufficient sample size. Conclusions: PTSD and PTSD+TBI negatively affect behavioral and cognitive functioning, while TBI does not contribute independently. Whether progressive decline in uncinate fasciculus microstructure in Veterans with PTSD might account for cognitive decline should be further studied. Findings did not support an association between PTSD, TBI, and Alzheimer’s disease pathology based on amyloid and tau PET.
Igor Fortel, Liang Zhan, Olusola Ajilore, Yichao Wu, Scott Mackin, Alex Leow
Disrupted Excitation-Inhibition Balance in Cognitively Normal Individuals at Risk of Alzheimer’s Disease
Abstract: Background: Sex differences impact Alzheimer’s disease (AD) neuropathology, but cell-to-network level dysfunctions in the prodromal phase are unclear. Alterations in hippocampal excitation-inhibition balance (EIB) have recently been linked to early AD pathology. Objective: Examine how AD risk factors (age, APOE ε4, amyloid-β) relate to hippocampal EIB in cognitively normal males and females using connectome-level measures. Methods: Individuals from the OASIS-3 cohort (age 42-95) were studied (N = 437), with a subset aged 65+ undergoing neuropsychological testing (N = 231). Results: In absence of AD risk factors (APOE ε4/Aβ+), whole-brain EIB decreases with age more significantly in males than females (p = 0.021, β = -0.007). Regression modeling including APOE ε4 allele carriers (Aβ-) yielded a significant positive AGE-by-APOE interaction in the right hippocampus for females only (p = 0.013, β = 0.014), persisting with inclusion of Aβ+ individuals (p = 0.012, β = 0.014). Partial correlation analyses of neuropsychological testing showed significant associations with EIB in females: positive correlations between right hippocampal EIB with categorical fluency and whole-brain EIB with the Trail Making Test (p < 0.05). Conclusions: Sex differences in EIB emerge during normal aging and progresses differently with AD risk. Results suggest APOE ε4 disrupts hippocampal balance more than amyloid in females. Increased excitation correlates positively with neuropsychological performance in the female group, suggesting a duality in terms of potential beneficial effects prior to cognitive impairment. This underscores the translational relevance of APOE ε4 related hyperexcitation in females, potentially informing therapeutic targets or early interventions to mitigate AD progression in this vulnerable population.
Shuichi Sato, Takao Imaeda, Shunji Mugikura, Naoko Mori, Masaki Takanashi, Kazumi Hayakawa, Tomo Saito, Makiko Taira, Akira Narita, Mana Kogure, Ippei Chiba, Rieko Hatanaka, Kumi Nakaya, Ikumi Kanno, Ryosuke Ishiwata, Tomohiro Nakamura, Ikuko N. Motoike, Naoki Nakaya, Seizo Koshiba, Kengo Kinoshita, Shinichi Kuriyama, Soichi Ogishima, Fuji Nagami, Nobuo Fuse, Atsushi Hozawa
Association Between Olfactory Test Data with Multiple Levels of Odor Intensity and Suspected Cognitive Impairment: A Cross-Sectional Study
Abstract: Background: Olfactory function decline has recently been reported to be associated with a risk of cognitive impairment. Few population-based studies have included younger adults when examining the association between olfactory test data with multiple odor intensities and suspected cognitive impairment. Objective: We investigated the association between high-resolution olfactory test data with fewer odors and suspected cognitive impairments. We also examined the differences between older and younger adults in this association. Methods: The Japanese version of the Montreal Cognitive Assessment (MoCA-J) was administered to 1,450 participants, with three odor-intensity-level olfactometry using six different odors. Logistic regressions to discriminate suspected cognitive impairment were conducted to examine the association, adjusted for age, sex, education duration, and smoking history. Data were collected from the Program by Tohoku University Tohoku Medical Megabank Organization, with an additional olfactory test conducted between 2019 and 2021. Results: We generally observed that the lower the limit of distinguishable odor intensity was, the higher the MoCA-J score was. The combination of spearmint and stuffy socks contributed most to the distinction between suspected and unsuspected cognitive impairment. Furthermore, the association was significant in women aged 60–74 years (adjusted odds ratio 0.881, 95% confidence interval [0.790, 0.983], p = 0.024). Conclusions: The results indicate an association between the limit of distinguishable odor intensity and cognitive function. The olfactory test with multiple odor intensity levels using fewer odors may be applicable for the early detection of mild cognitive impairment, especially in older women aged 60–74 years.
Yuanyuan Du*, Xi Chen*, Bin Zhang3, Xing Jin, Zemin Wan, Min Zhan, Jun Yan, Pengwei Zhang, Peifeng Ke, Xianzhang Huang, Liqiao Han, Qiaoxuan Zhang *These authors contributed equally to this work.
Identification of Copper Metabolism Related Biomarkers, Polygenic Prediction Model, and Potential Therapeutic Agents in Alzheimer’s Disease
Abstract: Background: The underlying pathogenic genes and effective therapeutic agents of Alzheimer’s disease (AD) are still elusive. Meanwhile, abnormal copper metabolism is observed in AD brains of both human and mouse models. Objective: To investigate copper metabolism-related gene biomarkers for AD diagnosis and therapy. Methods: The AD datasets and copper metabolism-related genes (CMGs) were downloaded from GEO and GeneCards database, respectively. Differentially expressed CMGs (DE-CMGs) performed through Limma, functional enrichment analysis and the protein-protein interaction were used to identify candidate key genes by using CytoHubba. And these candidate key genes were utilized to construct a prediction model by logistic regression analysis for AD early diagnosis. Furthermore, ROC analysis was conducted to identify a single gene with AUC values greater than 0.7 by GSE5281. Finally, the single gene biomarker was validated by quantitative real-time polymerase chain reaction (qRT-PCR) in AD clinical samples. Additionally, immune cell infiltration in AD samples and potential therapeutic drugs targeting the identified biomarkers were further explored. Results: A polygenic prediction model for AD based on copper metabolism was established by the top 10 genes, which demonstrated good diagnostic performance (AUC values). COX11, LDHA, ATOX1, SCO1, and SOD1 were identified as blood biomarkers for AD early diagnosis. 20 agents targeting biomarkers were retrieved from DrugBank database, some of which have been proven effective for the treatment of AD. Conclusions: The five blood biomarkers and copper metabolism-associated model can differentiate AD patients from non-demented individuals and aid in the development of new therapeutic strategies.
Talia Salzman, Diana P. Tobón, Hannah Perreault, Farah Farhat, Sarah Fraser (Handling Associate Editor: Qu Tian)
Using Cognitive-Motor Dual-Tasks and Functional Near-Infrared Spectroscopy to Characterize Older Adults with and without Subjective Cognitive Decline
Abstract: Background: Subjective cognitive decline (SCD) refers to individuals who report persistent cognitive deficits but perform normally on neuropsychological tests. Performance may be facilitated by increased prefrontal cortex activation, known as neural compensation, and could be used to differentiate between older adults with and without SCD. Objective: This cross-sectional pilot study measured changes in the hemodynamic response (∆HbO2) using functional near-infrared spectroscopy (fNIRS) as well as cognitive and motor performance during fine and gross motor dual-tasks in older adults with and without SCD. Methods: Twenty older adults over 60 years old with (n = 10) and without (n = 10) SCD were recruited. Two experiments were conducted using 1) gross motor walking and 2) fine motor finger tapping tasks that were paired with an n-back working memory task. Participants also completed neuropsychological assessments and questionnaires on everyday functioning. Results: Repeated measures ANOVAs demonstrated slower response times during dual-task gait compared to the single task (p = 0.032) and in the non-SCD group, slower gait speed was also observed in the dual compared to single task (p = 0.044). Response times during dual-task finger tapping were slower than the single task (p = 0.049) and greater ∆HbO2 was observed overall in the SCD compared to non-SCD group (p = 0.002). Conclusions: Examining neural and performance outcomes revealed differences between SCD and non-SCD groups and single and dual-tasks. Greater brain activation during dual-task finger tapping may reflect neural compensation, which should be examined in a larger sample and longitudinally to better characterize SCD.
Shanshan Wang, Suzhi Liu, Shaofa Ke, Wenjun Zhou, Tengwei Pan, for the Alzheimer’s Disease Neuroimaging Initiative
APOE ε4 Status and Plasma p-tau181 Levels May Influence Memory and Executive Function Decline in Older Adults Without Dementia
Abstract: Background: Elevated tau phosphorylation has been linked to the Apolipoprotein E (APOE) ε4 allele, which is considered one of the most significant genes related to Alzheimer's disease (AD). However, it is uncertain whether the impact of increased plasma tau phosphorylated at threonine 181 (p-tau181) on memory and executive function decline would be greater among APOE ε4 carriers. Objective: To investigate the effects of plasma p-tau181 and APOE ε4 on memory and executive function. Methods: The longitudinal analysis included 608 older adults without dementia (aged 72±7 years; 47% female; follow-up period of 1.59±1.47 years) from the ADNI dataset, including 180 individuals with normal cognition and 429 individuals with mild cognitive impairment. Linear mixed-effects models were utilized to assess the contributions of APOE ε4 status and plasma p-tau181 to longitudinal changes in memory composite score and executive function composite score. Results: At baseline, the APOE ε4+/Tau+ group exhibited poorer performance in memory composite score and executive function composite score, and an elevated load of cerebrospinal fluid Aβ and tau pathologies. To further understand longitudinal changes, we compared groups directly based on plasma p-tau181 and APOE ε4 status (four groups: APOE ε4-/Tau-, APOE ε4-/Tau+, APOE ε4+/Tau-, APOE ε4+/Tau+). Both the memory composite score and executive function composite score showed a significantly greater decline in the APOE ε4+/Tau+ group than in all other groups. Conclusions: Our findings indicate that there is an interaction between plasma p-tau181 levels and APOE ε4 status, which contributes to the longitudinal changes of memory and executive function decline in older adults without dementia.
Gulam Mustafa Hasan, Anas Shamsi, Sukhwinder Singh Sohal, Manzar Alam, Md. Imtaiyaz Hassan (Handling Associate Editor: Rekha Khandia)
Structure-Based Identification of Natural Compounds as Potential RET-Kinase Inhibitors for Therapeutic Targeting of Neurodegenerative Diseases
Abstract: Background: Tyrosine-protein kinase receptor Ret (RET), a proto-oncogene, is considered as an attractive drug target for cancer and neurodegenerative diseases, including Alzheimer’s disease (AD). Objective: We aimed to identify potential inhibitors of RET kinase among natural compounds present in the ZINC database. Methods: A multistep structure-based virtual screening approach was used to identify potential RET kinase inhibitors based on their binding affinities, docking scores, and interactions with the biologically important residues of RET kinase. To further validate the potential of these compounds as therapeutic leads, molecular dynamics (MD) simulations for 100 ns were carried out and subsequently evaluated the stability, conformational changes, and interaction mechanism of RET in-complex with the elucidated compounds. Results: Two natural compounds, ZINC02092851 and ZINC02726682, demonstrated high affinity, specificity for the ATP-binding pocket of RET and drug-likeness properties. The MD simulation outputs indicated that the binding of both compounds stabilizes the RET structure and leads to fewer conformational changes. Conclusions: The findings suggest that ZINC02092851 and ZINC02726682 may be potential inhibitors for RET, offering valuable leads for drug development against RET-associated diseases. Our study provides a promising avenue for developing new therapeutic strategies against complex diseases, including AD. Identifying natural compounds with high affinity and specificity for RET provides a valuable starting point for developing novel drugs that could help combat these debilitating diseases.
Yu Nakamura, Kohei Narita, Rei Kim, Kenichi Nishiyama, Takashi Kikuchi, Ichiro Ishikawa, Hiroshi Aoki
Long-Term Safety, Tolerability, and Efficacy of a Transdermal Donepezil Patch in Patients with Severe Alzheimer’s Disease
Abstract: Background: Oral formulations are not suitable for demented patients with dysphagia, those refuse to take tablets, or those with drug compliance problem. However, only oral formulations of donepezil hydrochloride are approved for the treatment of severe Alzheimer’s disease in Japan. Objective: To evaluate the safety, tolerability, and efficacy of long-term application of a 55.0 mg transdermal donepezil patch switched from a 10 mg oral donepezil hydrochloride tablet, for the treatment of patients with severe Alzheimer’s disease. Methods: A 52-week, multicenter, open-label, uncontrolled (phase III) study (jRCT2080224612) was conducted in Japan between April 2019 and August 2021. A 10 mg donepezil hydrochloride tablet was administered once a day for four weeks; a 55.0 mg donepezil patch was then applied once a day for 52 weeks in patients with severe Alzheimer’s disease. Results: Of 64 patients received the patch, 45 completed the 52-week period. The overall discontinuation rate was 29.7% (19/64). Among the 19 patients discontinued, six patients 9.4% (6/64) discontinued due to adverse events. The incidence of adverse events at application sites was 67.2% (43/64), including application site erythema 29.7% (19/64), application site pruritus 25.0% (16/64), and contact dermatitis 20.3% (13/64). Adverse events were mild and did not increase with time, demonstrating a favorable safety profile. Cognitive function, measured using the Mini-Mental State Examination, was maintained for up to 24 weeks. Conclusions: Adverse events were considered manageable in a clinical setting. The long-term application of a 55.0 mg donepezil patch once a day was feasible treatment in patients with severe Alzheimer’s disease.
Shabana R. Ziyad, May Altulyan, Meshal Alharbi
SHMAD: A Smart Health Care System to Monitor Alzheimer’s Disease Patients
Abstract: Background: In the digital era monitoring the patient’s health status is more effective and consistent with smart healthcare systems. Smart health care facilitates secure and reliable maintenance of patient data. Sensors, machine learning algorithms, Internet of things, and wireless technology has led to the development of Artificial Intelligence-driven Internet of Things models. Objective: This research study proposes an Artificial Intelligence driven Internet of Things model to monitor Alzheimer’s disease patient condition. The proposed Smart health care system to monitor and alert caregivers of Alzheimer’s disease patients includes different modules to monitor the health parameters of the patients. This study implements the detection of fall episodes using an artificial intelligence model in Python. Methods: The fall detection model is implemented with data acquired from the IMU open dataset. The ensemble machine learning algorithm AdaBoost performs classification of the fall episode and daily life activity using the feature set of each data sample. The common machine learning classification algorithms are compared for their performance on the IMU fall dataset. Results: AdaBoost ensemble classifier exhibits high performance compared to the other machine learning algorithms. The AdaBoost classifier shows 100% accuracy for the IMU dataset. This high accuracy is achieved as multiple weak learners in the ensemble model classify the data samples in the test data accurately. Conclusions: This study proposes a smart healthcare system for monitoring Alzheimer’s disease patients. The proposed model can alert the caregiver in case of fall detection via mobile applications installed in smart devices.
Haruhisa Fukuda, Hiroshi Kanzaki, Fumiko Murata, Megumi Maeda, Manabu Ikeda (Handling Associate Editor: Bernhard Michalwosky)
Disease Burden and Progression in Patients with New-Onset Mild Cognitive Impairment and Alzheimer’s Disease Identified from Japanese Claims Data: Evidence from the LIFE Study
Abstract: Background: Accurate epidemiological data on mild cognitive impairment (MCI) and Alzheimer’s disease (AD) can inform the development of prevention and control measures, but there is a lack of such data in Japan. Objective: To investigate the disease burden and progression in patients with new-onset MCI or AD in Japan. Methods: Using claims data, this multi-region cohort study was conducted on new-onset MCI and AD patients in 17 municipalities from 2014 to 2021. To characterize the patients, we investigated their age, comorbidities, and long-term care (LTC) needs levels at disease onset according to region type (urban, suburban, or rural). Disease burden was examined using health care expenditures and LTC expenditures, which were estimated for 1, 2, and 3 years after disease onset. Kaplan-Meier curves were plotted for AD progression in new-onset MCI patients and death in new-onset AD patients. Results: We analyzed 3,391 MCI patients and 58,922 AD patients. In MCI and AD patients, health care expenditures were high in the first year ($13,035 and $15,858, respectively), but had declined by the third year ($8,278 and $10,414, respectively). In contrast, LTC expenditures (daily living support) steadily increased over the 3-year period (MCI patients: $1,767 to $3,712, AD patients: $6,932 to $9,484). In the third year after disease onset, 30.9% of MCI patients developed AD and 23.3% of AD patients had died. Conclusions: This provides an important first look at the disease burden and progression of MCI and AD in Japan, which are high-priority diseases for a rapidly aging population.
Skylar Davidson, Gayle Allenback, Boris Decourt, Marwan N. Sabbagh
Type 2 Diabetes Comorbidity and Cognitive Decline in Patients with Alzheimer’s Disease
Abstract: Background: Although insulin dysregulation and resistance likely participate in Alzheimer’s disease (AD) etiologies, little is known about the correlation between type 2 diabetes mellitus (T2DM) and the progression of cognitive decline in patients with AD. Objective: To determine whether AD patients with T2DM experience more rapid cognitive decline than those without T2DM. Methods: All cognitive performance data and the presence or absence of T2DM comorbidity in patients with AD were derived from the US National Alzheimer’s Coordinating Center’s (NACC) Uniform Data Set (UDS). A search of the UDS identified 3055 participants with AD who had more than one epoch completed. The data set culled clinically diagnosed AD dementia patients who were assessed for diabetes type identified during at least 1 visit. These patients were divided into 2 groups based on whether they had a diagnosis of T2DM. The data from these groups were then analyzed for differences in cognitive decline based on neuropsychological test battery scores and a Clinician Dementia Rating using a general linear model. Results: Comparisons of the mean scores for 16 selected tests from the neuropsychological test battery showed no significant differences in baseline scores and scores at subsequent visits between the T2DM and nondiabetic groups. Conclusions: The results revealed no differences in cognitive decline metrics over the course of 5 visits in either study group. These data indicate that the presence of T2DM does not increase the rate of cognitive decline in AD. This finding contradicts expected disease burden and will need to be explored further.
Debra A. Fleischman, Konstantinos Arfanakis, Shengwei Zhang, Sue E. Leurgans, Lisa L. Barnes, David A. Bennett, David X. Marquez, Melissa Lamar
Acculturation in Context and Brain Health in Older Latino Adults: A Diffusion Tensor Imaging Study
Abstract: Background: Latinos are at higher risk of developing mild cognitive impairment (MCI) and Alzheimer’s disease than non-Latino Whites. Acculturation factors may influence this risk, yet there are few studies that have examined associations of acculturation, particularly in the context of socioenvironmental and familial factors, and brain health in older Latinos. Objective: To examine potential associations between acculturation in context and brain health in older Latinos. Methods: Using three previously established composites of acculturation-in-context, (acculturation-related: nativity status, language preference, acculturation scores; contextually-related socioenvironmental: perceived discrimination, loneliness/social isolation, social network size; and familism), and diffusion-tensor imaging (DTI), associations with white matter structural integrity were examined in 92 Latino adults without dementia participating in one of three epidemiological studies of aging. Linear regression models were used to test associations with DTI-derived metrics (fractional anisotropy, FA; trace) as separate outcomes and acculturation composite scores as individual predictors, while adjusting for age, sex, education, scanner, and white matter hyperintensities (voxelwise and total volumes normalized by intracranial volume). Results: Higher scores on the socioenvironmental composite were associated with lower FA in two clusters of left-hemisphere connections. Cluster 1 was dominated by both short association pathways connecting frontal regions and projection pathways connecting frontal regions with the thalamus. Cluster 2 was dominated by long association pathways connecting parietal, frontal, and temporal regions. Conclusions: This study of older Latino adults demonstrated an association between reduced brain white matter integrity and contextually related socioenvironmental experiences known to increase risk of MCI and Alzheimer’s disease.
Karolina Sejunaite, Frederic Gaucher, Claudia Lanza, Matthias W. Riepe (Handling Associate Editor: Carlo Abbate)
Clock Drawing Test: Types of Errors and Accuracy in Early Cognitive Screening
Abstract: Background: Clock Drawing Test (CDT) is a commonly used screening tool for cognitive disorders, known for its ease of administration and scoring. Despite frequent use by clinicians, CDT is criticized for its poor predictive value in mild cases of impairment. Objective: To evaluate CDT as a screening tool for early stage of cognitive impairment in biomarker-verified Alzheimer’s disease (AD) and depressive disorder (DD). Methods: We analyzed CDT of 172 patients with verified AD, 70 patients with DD, in whom neurodegenerative disorder was excluded using cerebrospinal fluid biomarkers, and 58 healthy older adults. CDT was scored using the semi-quantitative (Shulman) and itemized criteria (adapted from Mendez). Results: Logistic regression showed that for both DD and AD patients with high Mini-Mental State Examination (MMSE) scores (27 and above) the significant predicting variable is uneven number spacing. As MMSE deteriorates (24-26 points), an additional error of setting clock hands is predictive of the disease. In the low MMSE condition, CDT showed an acceptable discrimination for AD (AUC itemized 0.740, Shulman 0.741) and DD (AUC itemized 0.827, Shulman 0.739) using both scoring methods. In the high MMSE condition, discrimination rates were acceptable using itemized scoring but poor using Shulman scoring for both AD (AUC itemized 0.707, Shulman 0.677) and DD (AUC itemized 0.755, Shulman 0.667) groups. Conclusions: Ideally, modern diagnostic process should take place before the cognitive performance drops beneath the healthy range. This makes CDT of little use when screening patients with very mild cognitive deficits.
Sid E. O’Bryant, Fan Zhang, Leigh A. Johnson, James Hall, Melissa Petersen, Esther S. Oh, Constantine G. Lyketsos, Robert A. Rissman
Precision Medicine for Preventing Alzheimer’s Disease: Analysis of the ADAPT Study
Abstract: Background: The Alzheimer’s Disease Anti-inflammatory Prevention Trial (ADAPT) was the first-ever large-scale anti-inflammatory prevention trial targeting Alzheimer’s disease. Objective: The overall goal of this study was to evaluate predictive blood biomarker profiles that identified individuals most likely to be responders on NSAID treatment or placebo at 12 and 24 months. Methods: Baseline (n=193) and 12-month (n=562) plasma samples were assayed. The predictive biomarker profile was generated using SVM analyses with response on treatment (yes/no) as the outcome variable. Results: Baseline (AUC=0.99) and 12-month (AUC=0.99) predictive biomarker profiles were highly accurate in predicting response on Celecoxib arm at 12 and 24 months. The baseline (AUC=0.95) and 12-month (AUC=0.9) predictive biomarker profile predicting response on Naproxen were also highly accurate at 12 and 24 months. The baseline (AUC=0.93) and 12-month (AUC=0.99) predictive biomarker profile was also highly accurate in predicting response on placebo. As with our prior work, the profiles varied by treatment arm. Conclusions: The current results provide additional support for a precision medicine model for treating and preventing Alzheimer’s disease.
Jan Krzysztof Blusztajn, Nurgul Aytan, Thekkelnaycke Rajendiran, Tiffany J. Mellott, Tanu Soni, Charles F. Burant, Geidy E. Serrano, Thomas G. Beach, Honghuang Lin, Thor D. Stein
Cerebral Gray and White Matter Monogalactosyl Diglyceride Levels Rise with the Progression of Alzheimer’s Disease
Abstract: Background: Multiple studies have reported brain lipidomic abnormalities in Alzheimer’s disease (AD) that affect glycerophospholipids, sphingolipids, and fatty acids. However, there is no consensus regarding the nature of these abnormalities, and it is unclear if they relate to disease progression. Objective: Monogalactosyl diglycerides (MGDGs) are a class of lipids which have been recently detected in the human brain. We sought to measure their levels in postmortem human brain and determine if these levels correlate with the progression of the AD-related traits. Methods: We measured MGDGs by ultrahigh performance liquid chromatography tandem mass spectrometry in postmortem dorsolateral prefrontal cortex gray matter and subcortical corona radiata white matter samples derived from three cohorts of participants: the Framingham Heart Study, the Boston University Alzheimer’s Disease Research Center, and the Arizona Study of Aging and Neurodegenerative Disorders/Brain and Body Donation Program (total n=288). Results: We detected 40 molecular species of MGDGs (including diacyl and alkyl/acyl compounds) and found that the levels of 29 of them, as well as total MGDG levels, are positively associated with AD-related traits including pathologically confirmed AD diagnosis, clinical dementia rating, Braak and Braak stage, neuritic plaque score, phospho-Tau AT8 immunostaining density, levels of phospho-Tau396 and levels of Aβ40. Increased MGDG levels were present in both gray and white matter, indicating that they are widespread and likely associated with myelin-producing oligodendrocytes—the principal cell type of white matter. Conclusions: Our data implicate the MGDG metabolic defect as a central correlate of clinical and pathological progression in AD.
Jeroen Bruinsma, Irene Heger, Vasileios S. Loukas, Thomas Kassiotis, Georgia Karanasiou, Dimitrios I. Fotiadis, Sten Hanke, Rik Crutzen
Public Perspectives on Lifestyle-Related Behavior Change for Dementia Risk Reduction: An Exploratory Qualitative Study in the Netherlands
Abstract: Background: There is accumulating evidence that addressing modifiable risk and protective factors has an impact on dementia rates. Insight into the public’s perspectives on dementia risk reduction is needed to inform future individual-level interventions and public health approaches. Objective: This study explores the publics’ openness towards dementia risk reduction and willingness towards changing lifestyle behavior to reduce the future risk for dementia. Methods: Using a screening questionnaire, participants were purposively selected based on lifestyle behaviors that are associated with dementia risk. One-on-one interviews were used to explore their openness towards dementia risk reduction and willingness towards behavior change. Independently, two researchers performed an inductive content analysis. Results: Interviews were conducted with 23 participants aged from 40 to 79 years. Main themes that were identified from the data were: 1) abstractness of dementia risk reduction, 2) ambivalence towards changing behavior, 3) negative self-image and low behavioral control, and 4) all-or-nothing thinking about lifestyle change. Conclusions: The concept of dementia risk reduction seems difficult to translate to the personal context, particularly if individuals perceive that dementia would occur decades in the future. This is problematic because a large proportion of the public needs a healthier lifestyle to reduce the incidence of dementia. Translating healthy intentions into behavior is complex and involves overcoming a variety of barriers that complicate dementia risk reduction initiatives. Support is needed for individuals who experience additional obstacles that obstruct commencing to a healthier lifestyle (e.g., negative self-image, engaging in multiple unhealthy behaviors, unrealistic perceptions about lifestyle change).
Shayan Nik Akhtar, Qun Lu (Handling Associate Editor: Weiming Xia)
RhoA-LIMK Signaling Axis Reveals Rostral-Caudal Plane and Spatial Dysregulation in the Brain of Alzheimer’s Disease Mouse Models
Abstract: Background: RhoA signaling is widely reported to be dysregulated in Alzheimer’s disease (AD), but its therapeutic targeting demonstrated mixed outcomes. We hypothesize that the activation and inactivation states of RhoA and LIMK are different in the cortex and in subregions of hippocampus along the rostral-caudal dimensions. Objective: We intended to elucidate the plane and spatial dependent RhoA signaling in association with AD. Methods: We applied antibody pRhoA that recognizes an inactive state of RhoA (S188 phosphorylation) and antibody pLIMK against an active state of LIMK (T508 phosphorylation) to investigate RhoA signaling in wildtype (WT) and triple transgenic AD (3xTg-AD) mouse model. We prepared serial sections from the rostral to caudal coronal planes of the entire mouse brain followed by immunofluorescence staining with pRhoA and pLIMK antibodies. Results: Both pRhoA and pLIMK elicited a shift of expression pattern from rostral to caudal planes. Additionally, pRhoA demonstrated dynamic redistribution between the nucleus and cytoplasm. pLIMK did not show such nucleus and cytoplasm redistribution but the expression level was changed from rostral to caudal planes. At some planes, pRhoA showed an increasing trend in expression in the cortex but a decreasing trend in the dentate gyrus of the 3xTg-AD mouse hippocampus. pLIMK tends to decrease in the cortex but increase in the dentate gyrus of 3xTg-AD mouse hippocampus. Conclusions: RhoA activation is dysregulated in both human and mouse AD brains, and the RhoA-LIMK signaling axis reveals spatial dysregulation along the rostral-caudal plane dimensions.
Keita Sakurai, Daita Kaneda, Satoru Morimoto, Yuto Uchida, Shohei Inui, Yasuyuki Kimura, Takashi Kato, Kengo Ito, Yoshio Hashizume
Asymmetric Cerebral Peduncle Atrophy: A Simple Diagnostic Clue for Distinguishing Frontotemporal Lobar Degeneration from Alzheimer’s Disease
Abstract: Background: Due to confusing clinicoradiological features such as amnestic symptoms and hippocampal atrophy in frontotemporal lobar degeneration (FTLD), antemortem differentiation between FTLD and Alzheimer’s disease (AD) can be challenging. Although asymmetric atrophy of the cerebral peduncle is regarded as a representative imaging finding in some disorders of the FTLD spectrum, the utility of this finding has not been sufficiently evaluated for differentiating between FTLD and AD. Objective: This study aimed to explore the diagnostic performance of asymmetric cerebral peduncle atrophy on axial magnetic resonance imaging as a simple radiological discriminator between FTLD and AD. Methods: Seventeen patients with pathologically confirmed FTLD, including six with progressive supranuclear palsy, three with corticobasal degeneration, eight with TAR DNA-binding protein 43 (FTLD-TDP), and 11 with pathologically confirmed AD, were investigated. Quantitative indices representing the difference between the volumes of the bilateral cerebral peduncles (i.e., cerebral peduncular asymmetry index [CPAI]), the voxel-based specific regional analysis system for Alzheimer's disease (VSRAD) Z-score representing the degree of hippocampal atrophy, and semiquantitative visual analysis to evaluate the asymmetry of the cerebral peduncle (visual assessment of cerebral peduncular asymmetry: VACPA) were compared between the two groups. Results: Contrary to the VSRAD Z-score, the CPAI and VACPA scores demonstrated higher diagnostic performance in differentiating patients with FTLD from those with AD (areas under the receiver operating characteristic curve of 0.88, 082, and 0.60, respectively). Conclusions: Quantitative and visual analytical techniques can differentiate between FTLD and AD. These simple methods may be useful in daily clinical practice.
Alfonso Parreño Torres, Carlos Roncero-Parra, Alejandro L. Borja, Jorge Mateo-Sotos
Inter-Hospital Advanced and Mild Alzheimer’s Disease Classification Based on Electroencephalogram Measurements via Classical Machine Learning Algorithms
Abstract: Background: In pursuit of diagnostic tools capable of targeting distinct stages of Alzheimer’s disease (AD), this study explores the potential of electroencephalography (EEG) combined with machine learning (ML) algorithms to identify patients with mild or moderate AD (ADM) and advanced AD (ADA). Objective: This study aims to assess the classification accuracy of six classical ML algorithms using a dataset of 668 patients from multiple hospitals. Methods: The dataset comprised measurements obtained from 668 patients, distributed among control, ADM, and ADA groups, collected from five distinct hospitals between 2011 and 2022. For classification purposes, six classical ML algorithms were employed: support vector machine, Bayesian linear discriminant analysis, decision tree, Gaussian Na.ve Bayes, K-nearest neighbor, and random forest. Results: The RF algorithm exhibited outstanding performance, achieving a remarkable balanced accuracy of 93.55% for ADA classification and 93.25% for ADM classification. The consistent reliability in distinguishing ADA and ADM patients underscores the potential of the EEG-based approach for AD diagnosis. Conclusions: By leveraging a dataset sourced from multiple hospitals and encompassing a substantial patient cohort, coupled with the straightforwardness of the implemented models, it is feasible to attain notably robust results in AD classification.
Yanyan Yang*, Mengfan Li*, Bing Leng, Ran Yao, Song Xue, Ming Tan, Hairong Sun, Jinbiao Zhang *These authors contributed equally to this work.
Alzheimer’s Disease Biomarkers and Complement Proteins Mediate the Impact of Sleep Fragmentation on Cognitive Impairment in Obstructive Sleep Apnea Patients Without Dementia
Abstract: Background: Cognitive impairment is common in patients with obstructive sleep apnea (OSA). Previous studies indicated that intermittent hypoxia, sleep fragmentation, and depressive symptoms were associated with cognitive impairment in OSA patients. Objective: The study aimed to investigate whether sleep characteristics and depressive symptoms affected cognitive abilities mediated by Alzheimer’s disease (AD) biomarkers and complement proteins in OSA patients without dementia. Methods: A total of 317 subjects without dementia who had undergone polysomnography, cognitive and neuropsychological evaluations, were recruited. Neuronal-derived exosomes (NDEs) levels for amyloid-β (Aβ), total tau (T-tau), and tau phosphorylated 62 at threonine 181 (P-T181-tau) and astrocyte-derived exosomes (ADEs) levels for complement proteins were measured. Mediation analysis were performed to explore the mediation effects of AD biomarkers (Aβ42, T-tau, P-T181-tau) and complement proteins (C3b and C5b-9) on cognition. Results: The findings revealed that the association between sleep fragmentation and cognition was mediated by Aβ42 (the percentage varied from 18.25% to 30.6%), P-T181-tau (the percentage varied from 24.36% to 32.3%), and C5b-9 (the percentage varied from 30.88% to 60.7%). The influence of depressive symptoms on cognition was only mediated via C3b (the percentage varied from 24.1% to 36.6%). Conclusions: In OSA patients without dementia, Aβ42 and P-T181-tau levels in NDEs, and C5b-9 levels in ADEs mediated the impact of sleep fragmentation on cognitive impairment, and C3b levels in ADEs mediated the impact of depressive symptoms on cognitive impairment.
Amber Watts, Stephen Haneline, Kathleen A. Welsh-Bohmer, Jingtao Wu, Robert Alexander, Russell H. Swerdlow, Daniel K. Burns, Ann M. Saunders
TOMM40 ‘523 Genotype Distinguishes Patterns of Cognitive Improvement for Executive Function in APOE ε3 Homozygotes
Abstract: Background: TOMM40 ‘523 has been associated with cognitive performance and risk for developing Alzheimer’s disease independent of the effect of APOE genotype. Few studies have considered the longitudinal effect of this genotype on change in cognition over time. Objective: Our objective was to evaluate the relationship between TOMM40 genotype status and change in cognitive performance in the TOMMORROW study, which was designed to prospectively evaluate an algorithm that includes TOMM40 ‘523 for genetic risk for conversion to mild cognitive impairment. Methods: We used latent growth curve models to estimate the effect of TOMM40 allele carrier (short, very long) status on the intercept and slope of change in cognitive performance in four broad cognitive domains (attention, memory, executive function, and language) and a combined overall cognitive score over 30 months. Results: TOMM40 very long allele carriers had significantly lower baseline performance for the combined overall cognitive function score (B = -0.088, p = 0.034) and for the executive function domain score (B = -0.143, p = 0.013). Slopes for TOMM40 very long carriers had significantly greater increases over time for the executive function domain score only. In sensitivity analyses, the results for executive function were observed in participants who remained clinically stable, but not in those who progressed clinically over the study duration. Conclusions: Our results add to the growing body of evidence that TOMM40, in the absence of APOE ε4, may contribute to cognitive changes with aging and dementia and support the view that mitochondrial function is an important contributor to Alzheimer's diseaes risk.
Xuan Xu, Hui Wang, Qing-Ye Zhang, Xiang-Yu Meng, Xin-Xing Li, Hong-Yu Zhang (Handling Associate Editor: Jiu Chen)
Dissecting Mitochondrial Mechanisms of Alzheimer’s Disease Using Gene Dependency Network and Its Implications for Discovering Nutrients Combatting the Disease
Abstract: Background: Alzheimer's disease (AD) is the leading cause of dementia, with its prevalence increasing as the global population ages. AD is a multifactorial and intricate neurodegenerative disease with pathological changes varying from person to person. Because the mechanism of AD is highly controversial, effective treatments remain a distant prospect. Currently, one of the most promising hypotheses posits mitochondrial dysfunction as an early event in AD diagnosis and a potential therapeutic target. Objective: Here, we adopted a systems medicine strategy to explore the mitochondria-related mechanisms of AD. Then, its implications for discovering nutrients combatting the disease were demonstrated. Methods: We employed conditional mutual information to construct AD gene dependency networks. Furthermore, the GeneRank algorithm was applied to prioritize the gene importance of AD patients and identify potential anti-AD nutrients targeting crucial genes. Results: The results suggested that two highly interconnected networks of mitochondrial ribosomal proteins (MRPs) play an important role in the regulation of AD pathology. The close association between mitochondrial ribosome dysfunction and AD was identified. Additionally, we proposed seven nutrients with potential preventive and ameliorative effects on AD, five of which have been supported by experimental reports. Conclusions: Our study explored the important regulatory role of MRP genes in AD, which has significant implications for AD prevention and treatment.
Thomas Guieysse, Roxane Lamothe, Marion Houot, Solofo Razafimahatratra, Takfarinas Medani, François-Xavier Lejeune, Gérard Dreyfus, André Klarsfeld, Dimitrios Pantazis, Etienne Koechlin, Katia Andrade
Detecting Anosognosia from the Prodromal Stage of Alzheimer’s Disease
Abstract: Background: Though not originally developed for this aim, the Healthy Aging Brain Care Monitor (HABC-M) seems a valuable instrument for assessing anosognosia in Alzheimer's disease (AD). Objectives: Our study aimed at 1) investigating the validity of the HABC-M (31 items), and its cognitive, psychological, and functional subscales, in discriminating AD patients from controls; 2) exploring whether the HABC-M discrepancy scores between the self-reports of patients/controls in these different domains and the respective ratings provided by their caregivers/informants correlate with an online measure of self-awareness; 3) determining whether the caregiver burden level, also derived from the HABC-M, could add additional support for detecting anosognosia. Methods: The HABC-M was administered to 30 AD patients and 30 healthy controls, and to their caregivers/informants. A measure of online awareness was established from subjects' estimation of their performances in a computerized experiment. Results: The HABC-M discrepancy scores distinguished AD patients from controls. The cognitive subscale discriminated the two groups from the prodromal AD stage, with an AUC of 0.88 [95% CI: 0.78;0.97]. Adding the caregiver burden level raised it to 0.94 [0.86;0.99]. Significant correlations between the HABC-M and online discrepancy scores were observed in the patients group, providing convergent validity of these methods. Conclusions: The cognitive HABC-M (six items) can detect anosognosia across the AD spectrum. The caregiver burden (four items) may corroborate the suspicion of anosognosia. The short-hybrid scale, built from these 10 items instead of the usual 31, showed the highest sensitivity for detecting anosognosia from the prodromal AD stage, which may further help with timely diagnosis.
Łukasz Witucki, Kamila Borowczyk, Joanna Suszyńska-Zajczyk, Ewelina Warzych, Piotr Pawlak, Hieronim Jakubowski
Deletion of the Homocysteine Thiolactone Detoxifying Enzyme Bleomycin Hydrolase, in Mice, Causes Memory and Neurological Deficits and Worsens Alzheimer’s Disease-Related Behavioral and Biochemical Traits in the 5xFAD Model of Alzheimer’s Disease
Abstract: Background: Bleomycin hydrolase (BLMH), a homocysteine (Hcy)-thiolactone detoxifying enzyme, is attenuated in Alzheimer’s disease (AD) brains. Blmh loss causes astrogliosis in mice while the loss of histone demethylase Phf8, which controls mTOR signaling, causes neuropathy in mice and humans. Objective: To examine how Blmh gene deletion affects the Phf8/H4K20me1/mTOR/autophagy pathway, amyloid-β (Aβ) accumulation, and cognitive/neuromotor performance in mice. Methods: We generated a new mouse model of AD, the Blmh-/-5xFAD mouse. Behavioral assessments were conducted by cognitive/neuromotor testing. Blmh and Phf8 genes were silenced in mouse neuroblastoma N2a-APPswe cells by RNA interference. mTOR- and autophagy-related proteins, and AβPP were quantified by western blotting and the corresponding mRNAs by RT-qPCR. Aβ was quantified by western blotting (brains) and by confocal microscopy (cells). Results: Behavioral testing showed cognitive/neuromotor deficits in Blmh-/- and Blmh-/-5xFAD mice. Phf8 was transcriptionally downregulated in Blmh-/- and Blmh-/-5xFAD brains. H4K20me1, mTOR, phospho-mTOR, and AβPP were upregulated while autophagy markers Becn1, Atg5, and Atg7 were downregulated in Blmh-/- and Blmh-/-5xFAD brains. Aβ was elevated in Blmh-/-5xFAD brains. These biochemical changes were recapitulated in Blmh-silenced N2a-APPswe cells, which also showed increased H4K20me1-mTOR promoter binding and impaired autophagy flux (Lc3-I, Lc3-II, p62). Phf8-silencing or treatments with Hcy-thiolactone or N-Hcy-protein, metabolites elevated in Blmh-/- mice, induced biochemical changes in N2a-APPswe cells like those induced by the Blmh-silencing. However, Phf8-silencing elevated Aβ without affecting AβPP. Conclusions: Our findings show that Blmh interacts with AβPP and the Phf8/H4K20me1/mTOR/autophagy pathway, and that disruption of those interactions causes Aβ accumulation and cognitive/neuromotor deficits.
Hao Tang, Yuhong Sun, Helene A. Fachim, To Ka Dorcas Cheung, Gavin P. Reynolds, Michael K. Harte
Elevated Expression of Two Pore Potassium Channel THIK-1 in Alzheimer’s Disease: An Inflammatory Mechanism
Abstract: Background: Tandem pore domain halothane-inhibited K+ channel 1 (THIK-1, coded by KCNK13) provides an upstream regulation of the activation of the NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome, which has been suggested as one of the key mechanisms of the pathological process in neurodegeneration mainly from in vitro and in vivo model systems studies. However, unequivocal evidence from neurodegenerative disorders has been lacking. Objective: To investigate the involvement of the THIK-1/NLRP3 pathway in the pathological process of Alzheimer’s disease (AD) and Parkinson’s disease (PD). Methods: This study investigated gene expression of markers in the THIK-1/NLRP3 pathway in an animal model representing AD as well as in human postmortem brains of AD and PD by quantitative real-time PCR. THIK-1 protein expression was determined using automated capillary electrophoresis immunoblotting. Furthermore, DNA methylation of KCNK13 was analysed in AD cohort by pyrosequencing. Results: A substantial upregulation of KCNK13, glial activation markers, NLRP3 inflammasome components, and IL1B was observed in the animal study. Increased expression of KCNK13 support an inflammatory glial cell activation in both advanced AD and PD. The increase in KCNK13 expression was also supported by downregulation in DNA methylation of KCNK13 in AD. Conclusions: The association between THIK-1 K+ channels expression and pathology changes indicates a THIK-1-induced activation of this glial subtype in AD and PD. Therefore, specific blocks of the microglial THIK-1 K+ channels at the early stage of AD and PD may be beneficial for the patients.
Christine Musyimi, David Ndetei, Levi Abisai Muyela, Joe Masila, Elizabeth Mutunga, Nicolas Farina
Integration and Evaluation of a Community-Level Dementia Screening Program in Kenya (DEM-SKY): A Protocol
Abstract: Background: In Kenya, many people are currently living with dementia without a formal diagnosis or support; often attributing symptoms to normal aging or as a consequence of past behaviors. Dementia screening is not commonplace within Kenya. Improving the supply (or opportunity) of dementia screening within the region may promote uptake, thus leading to more people to seek a formal diagnosis and subsequently receive support within the Kenyan healthcare system. Community Healthcare Workers (CHWs) have successfully demonstrated their value in delivering health interventions within Kenya and have strong links within local communities. Objective: To integrate and evaluate a community-level dementia screening program among older adults in rural Kenya. Methods: Through leveraging this resource, we will deliver dementia screening to older adults (≥60 years) within Makueni County, Kenya over a 6-month period. Here, we present a protocol for the process evaluation of a dementia screening in Kenya (DEM-SKY) program. The process evaluation seeks to understand the adoption, implementation, continuation, and implementation determinants, using quantitative and qualitative measures. Conclusions: Gaining perspectives of different participants involved in the program (i.e., older adults, CHWs, hospital staff, and trainers), will ensure that we understand the reason for successful (or unsuccessful) delivery of DEM-SKY.