2021 Alzheimer's disease facts and figures

Black Americans' perceptions of Alzheimer's disease, a healthy brain, and strategies for brain health promotion

Objectives

Lack of awareness of Alzheimer's disease (AD) among Black Americans may undermine their ability to identify potential AD risk. We examined Black Americans' perceptions and knowledge of AD, and views of a healthy brain, which may contribute to the development of effective and culturally sensitive strategies to address racial disparities in AD.

Methods

We conducted a mixed-methods study, integrating a cross-sectional survey of 258 older (>55 years) Black participants and qualitative interviews with a sub-sample of N = 29. Both data sets were integrated to inform the results.

Results

Participants endorsed having little knowledge of AD. While most participants reported practicing a healthy lifestyle to promote a healthy brain, the range of activities listed were limited. Participants made several suggestions to increase AD awareness, which includes using AD educational materials containing information that would benefit the whole family, not only older adults. Outreach approaches that address both individual behaviors and structural factors were also encouraged.

Conclusion

Our findings identify ongoing needs to improve AD awareness among traditionally under-represented groups.

Innovation

The study utilized novel approaches to examine participants' perspectives of AD that included a diverse sample of research naïve participants, and integrated exploration of participants' views of AD and brain health.

Strategies for measuring concentrations and forms of amyloid-β peptides

Alzheimer's disease (AD) is affecting more and more people worldwide without the effective treatment, while the existed pathological mechanism has been confirmed barely useful in the treatment. Amyloid-β peptide (Aβ), a main component of senile plaque, is regarded as the most promising target in AD treatment. Aβ clearance from AD brain seems to be a reliably therapeutic strategy, as the two exited drugs, GV-971 and aducanumab, are both developed based on it. However, doubt still exists. To exhaustive expound on the pathological mechanism of Aβ, rigorous analyses on the concentrations and aggregation forms are essential. Thus, it is attracting broad attention these years. However, most of the sensors have not been used in pathological studies, as the lack of the bridge between analytical chemist and pathologists. In this review, we made a brief introduce on Aβ-related pathological mechanism included in β-amyloid hypothesis to elucidate the detection conditions of sensor methods. Furthermore, a summary of the sensor methods was made, which were based on Aβ concentrations and form detections that have been developed in the past 10 years. As the greatest number of the sensors were built on fluorescent spectroscopy, electrochemistry, and Roman spectroscopy, detailed elucidation on them was made. Notably, the aggregation process is another important factor in revealing the progress of AD and developing the treatment methods, so the sensors on monitoring Aβ aggregation processes were also summarized.

Arterial spin labelling magnetic resonance imaging and perfusion patterns in neurocognitive and other mental disorders: a systematic review

We reviewed 33 original research studies assessing brain perfusion, using consensus guidelines from a "white paper" issued by the International Society for Magnetic Resonance in Medicine Perfusion Study Group and the European Cooperation in Science and Technology Action BM1103 ("Arterial Spin Labelling Initiative in Dementia"; https://www.cost.eu/actions/BM1103/ ). The studies were published between 2011 and 2023 and included participants with subjective cognitive decline plus; neurocognitive disorders, including mild cognitive impairment (MCI), Alzheimer's disease (AD), frontotemporal lobar degeneration (FTLD), dementia with Lewy bodies (DLB) and vascular cognitive impairment (VCI); as well as schizophrenia spectrum disorders, bipolar and major depressive disorders, autism spectrum disorder, attention-deficit/hyperactivity disorder, panic disorder and alcohol use disorder. Hypoperfusion associated with cognitive impairment was the major finding across the spectrum of cognitive decline. Regional hyperperfusion also was reported in MCI, AD, frontotemporal dementia phenocopy syndrome and VCI. Hypoperfused structures found to aid in diagnosing AD included the precunei and adjacent posterior cingulate cortices. Hypoperfused structures found to better diagnose patients with FTLD were the anterior cingulate cortices and frontal regions. Hypoperfusion in patients with DLB was found to relatively spare the temporal lobes, even after correction for partial volume effects. Hyperperfusion in the temporal cortices and hypoperfusion in the prefrontal and anterior cingulate cortices were found in patients with schizophrenia, most of whom were on medication and at the chronic stage of illness. Infratentorial structures were found to be abnormally perfused in patients with bipolar or major depressive disorders. Brain perfusion abnormalities were helpful in diagnosing most neurocognitive disorders. Abnormalities reported in VCI and the remaining mental disorders were heterogeneous and not generalisable.

Mitochondrial translation failure represses cholesterol gene expression via Pyk2-Gsk3β-Srebp2 axis

Neurodegenerative diseases and other age-related disorders are closely associated with mitochondrial dysfunction. We previously showed that mice with neuron-specific deficiency of mitochondrial translation exhibit leukoencephalopathy because of demyelination. Reduced cholesterol metabolism has been associated with demyelinating diseases of the brain such as Alzheimer's disease. However, the molecular mechanisms involved and relevance to the pathogenesis remained unknown. In this study, we show that inhibition of mitochondrial translation significantly reduced expression of the cholesterol synthase genes and degraded their sterol-regulated transcription factor, sterol regulatory element-binding protein 2 (Srebp2). Furthermore, the phosphorylation of Pyk2 and Gsk3β was increased in the white matter of p32cKO mice. We observed that Pyk2 inhibitors reduced the phosphorylation of Gsk3β and that GSK3β inhibitors suppressed degradation of the transcription factor Srebp2. The Pyk2-Gsk3β axis is involved in the ubiquitination of Srebp2 and reduced expression of cholesterol gene. These results suggest that inhibition of mitochondrial translation may be a causative mechanism of neurodegenerative diseases of aging. Improving the mitochondrial translation or effectiveness of Gsk3β inhibitors is a potential therapeutic strategy for leukoencephalopathy.

Assessment of disparities in timely diagnosis and comprehensive workup of cognitive impairment between English and Spanish speakers

BACKGROUND

Previous studies have examined disparities in dementia care that affect the U.S. Hispanic/Latino population, including clinician bias, lack of cultural responsiveness, and less access to health care. However, there is limited research that specifically investigates the impact of language barriers to health disparities in dementia diagnosis.

METHODS

In this retrospective cross-sectional study, 12,080 English- or Spanish- speaking patients who received an initial diagnosis of mild cognitive impairment (MCI) or dementia between July 2017 and June 2019 were identified in the Yale New Haven Health (YNHH) electronic medical record. To evaluate the timeliness of diagnosis, an initial diagnosis of MCI was classified as "timely", while an initial diagnosis of dementia was considered "delayed." Comprehensiveness of diagnosis was assessed by measuring the presence of laboratory studies, neuroimaging, specialist evaluation, and advanced diagnostics six months before or after diagnosis. Binomial logistic regressions were calculated with and without adjustment for age, legal sex, ethnicity, neighborhood disadvantage, and medical comorbidities.

RESULTS

Spanish speakers were less likely to receive a timely diagnosis when compared with English speakers both before (unadjusted OR, 0.65; 95% CI, 0.53-0.80, p <0.0001) and after adjusting for covariates (adjusted OR, 0.55; 95% CI, 0.40-0.75, p = 0.0001). Diagnostic services were provided equally between groups, except for referrals to geriatrics, which were more frequent among Spanish-speaking patients. A subgroup analysis revealed that Spanish-speaking Hispanic/Latino patients were less likely to receive a timely diagnosis compared to English-speaking Hispanic/Latino patients (adjusted OR, 0.53; 95% CI, 0.38-0.73, p = 0.0001).

CONCLUSIONS

Non-English language preference is likely to be a contributing factor to timely diagnosis of cognitive impairment. In this study, Spanish language preference rather than Hispanic/Latino ethnicity was a significant predictor of a less timely diagnosis of cognitive impairment. Policy changes are needed to reduce barriers in cognitive disorders care for Spanish-speaking patients.

Experiences of formal caregivers of elderly inpatients with physical disabilities in China: a qualitative study

AIM

To explore the views and experiences of formal caregivers caring for older inpatients with physical disabilities.

METHODS

It was a qualitative phenomenological study. Using purposive sampling, twelve formal caregivers were chosen in a tertiary comprehensive hospital in Hangzhou, China. Semi-structured, face-to-face interviews were conducted, guided by open-ended questions that focused on gaining rich insights into participants' views and experiences. Coding reliability thematic analysis was used to guide data analysis and categorize, based on Lazarus and Folkman's theory of transactional coping.

RESULTS

Four themes emerged from the data analysis: (1) Caregiving Threats. (2) motivations. (3) Responsibility Management. (4) Fear.

CONCLUSION

Despite facing significant pressure at work, formal caregivers of elderly inpatients with physical disabilities possess the drive and various coping strategies to excel in their role. Identifying caregivers' experiences of care can be helpful in improving resilience to stress and maintaining stability in formal caregivers.

Navigating the future of Alzheimer's care in Ireland - a service model for disease-modifying therapies in small and medium-sized healthcare systems

BACKGROUND

A new class of antibody-based drug therapy with the potential for disease modification is now available for Alzheimer's disease (AD). However, the complexity of drug eligibility, administration, cost, and safety of such disease modifying therapies (DMTs) necessitates adopting new treatment and care pathways. A working group was convened in Ireland to consider the implications of, and health system readiness for, DMTs for AD, and to describe a service model for the detection, diagnosis, and management of early AD in the Irish context, providing a template for similar small-medium sized healthcare systems.

METHODS

A series of facilitated workshops with a multidisciplinary working group, including Patient and Public Involvement (PPI) members, were undertaken. This informed a series of recommendations for the implementation of new DMTs using an evidence-based conceptual framework for health system readiness based on [1] material resources and structures and [2] human and institutional relationships, values, and norms.

RESULTS

We describe a hub-and-spoke model, which utilises the existing dementia care ecosystem as outlined in Ireland's Model of Care for Dementia, with Regional Specialist Memory Services (RSMS) acting as central hubs and Memory Assessment and Support Services (MASS) functioning as spokes for less central areas. We provide criteria for DMT referral, eligibility, administration, and ongoing monitoring.

CONCLUSIONS

Healthcare systems worldwide are acknowledging the need for advanced clinical pathways for AD, driven by better diagnostics and the emergence of DMTs. Despite facing significant challenges in integrating DMTs into existing care models, the potential for overcoming challenges exists through increased funding, resources, and the development of a structured national treatment network, as proposed in Ireland's Model of Care for Dementia. This approach offers a replicable blueprint for other healthcare systems with similar scale and complexity.

The interaction between insulin resistance and Alzheimer's disease: a review article

Insulin serves multiple functions as a growth-promoting hormone in peripheral tissues. It manages glucose metabolism by promoting glucose uptake into cells and curbing the production of glucose in the liver. Beyond this, insulin fosters cell growth, drives differentiation, aids protein synthesis, and deters degradative processes like glycolysis, lipolysis, and proteolysis. Receptors for insulin and insulin-like growth factor-1 are widely expressed in the central nervous system. Their widespread presence in the brain underscores the varied and critical functions of insulin signaling there. Insulin aids in bolstering cognition, promoting neuron extension, adjusting the release and absorption of catecholamines, and controlling the expression and positioning of gamma-aminobutyric acid (GABA). Importantly, insulin can effortlessly traverse the blood-brain barrier. Furthermore, insulin resistance (IR)-induced alterations in insulin signaling might hasten brain aging, impacting its plasticity and potentially leading to neurodegeneration. Two primary pathways are responsible for insulin signal transmission: the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway, which oversees metabolic responses, and the mitogen-activated protein kinase (MAPK) pathway, which guides cell growth, survival, and gene transcription. This review aimed to explore the potential shared metabolic traits between Alzheimer's disease (AD) and IR disorders. It delves into the relationship between AD and IR disorders, their overlapping genetic markers, and shared metabolic indicators. Additionally, it addresses existing therapeutic interventions targeting these intersecting pathways.

Advanced computational approaches to understand protein aggregation

Protein aggregation is a widespread phenomenon implicated in debilitating diseases like Alzheimer's, Parkinson's, and cataracts, presenting complex hurdles for the field of molecular biology. In this review, we explore the evolving realm of computational methods and bioinformatics tools that have revolutionized our comprehension of protein aggregation. Beginning with a discussion of the multifaceted challenges associated with understanding this process and emphasizing the critical need for precise predictive tools, we highlight how computational techniques have become indispensable for understanding protein aggregation. We focus on molecular simulations, notably molecular dynamics (MD) simulations, spanning from atomistic to coarse-grained levels, which have emerged as pivotal tools in unraveling the complex dynamics governing protein aggregation in diseases such as cataracts, Alzheimer's, and Parkinson's. MD simulations provide microscopic insights into protein interactions and the subtleties of aggregation pathways, with advanced techniques like replica exchange molecular dynamics, Metadynamics (MetaD), and umbrella sampling enhancing our understanding by probing intricate energy landscapes and transition states. We delve into specific applications of MD simulations, elucidating the chaperone mechanism underlying cataract formation using Markov state modeling and the intricate pathways and interactions driving the toxic aggregate formation in Alzheimer's and Parkinson's disease. Transitioning we highlight how computational techniques, including bioinformatics, sequence analysis, structural data, machine learning algorithms, and artificial intelligence have become indispensable for predicting protein aggregation propensity and locating aggregation-prone regions within protein sequences. Throughout our exploration, we underscore the symbiotic relationship between computational approaches and empirical data, which has paved the way for potential therapeutic strategies against protein aggregation-related diseases. In conclusion, this review offers a comprehensive overview of advanced computational methodologies and bioinformatics tools that have catalyzed breakthroughs in unraveling the molecular basis of protein aggregation, with significant implications for clinical interventions, standing at the intersection of computational biology and experimental research.

Effectiveness of a health education program for people with dementia and their family caregivers: An intervention by nurse practitioners

PURPOSE

This study assesses the effectiveness of a health education program on caregiving outcomes for people with dementia and their families.

METHODS

This quasi-experimental study involved 250 people with dementia and their family caregivers. Behavioral problems in people with dementia were assessed using the Chinese version of the Cohen-Mansfield Agitation Inventory-community form. Family caregiver outcomes were measured using the Agitation Management Self-Efficacy Scale, Caregiver Preparedness Scale, Competence Scale, and Community Resource Awareness and Utilization Assessment.

RESULTS

Following the intervention, the experimental group demonstrated significant improvements in terms of self-efficacy, preparedness, competence, and awareness and utilization of community resources among family caregivers. Additionally, the experimental group exhibited lower levels of behavioral problems among people with dementia.

CONCLUSIONS

This study helped improve caregiving outcomes for people with dementia and their family caregivers. Therefore, outpatient healthcare providers can utilize these findings to enhance care for this population.

Factors Associated with Costly Hospital Care among Patients with Dementia and Acute Respiratory Failure

Rationale: Understanding contributors to costly and potentially burdensome care for patients with dementia is of interest to healthcare systems and may facilitate efforts to promote goal-concordant care. Objective: To identify risk factors, in particular whether an early goals-of-care discussion (GOCD) took place, for high-cost hospitalization among patients with dementia and acute respiratory failure. Methods: We conducted an electronic health record-based retrospective cohort study of 298 adults with dementia hospitalized with respiratory failure (receiving ⩾48 h of mechanical ventilation) within an academic healthcare system. We collected demographic and clinical characteristics, including clinical markers of advanced dementia (weight loss, pressure ulcers, hypernatremia, mobility limitations) and intensive care unit (ICU) service (medical, surgical, neurologic). We ascertained whether a GOCD was documented within 48 hours of ICU admission. We used logistic regression to identify patient characteristics associated with high-cost hospitalization measured using the hospital system accounting database and defined as total cost in the top third of the sample (⩾$145,000). We examined a path model that included hospital length of stay as a final mediator between exposure variables and high-cost hospitalization. Results: Patients in the sample had a median age of 71 (IQR, 62-79) years. Approximately half (49%) were admitted to a medical ICU, 29% to a surgical ICU, and 22% to a neurologic ICU. More than half (59%) had a clinical indicator of advanced dementia. A minority (31%) had a GOCD documented within 48 hours of ICU admission; those who did had a 50% lower risk of a high-cost hospitalization (risk ratio, 0.50; 95% confidence interval, 0.2-0.8). Older age, limited English proficiency, and nursing home residence were associated with a lower likelihood of high-cost hospitalization, whereas greater comorbidity burden and admission to a surgical or neurologic ICU compared with a medical ICU were associated with a higher likelihood of high-cost hospitalization. Conclusions: Early GOCDs for patients with dementia and respiratory failure may promote high-value care by ensuring aggressive and costly life support interventions are aligned with patients' goals. Future work should focus on increasing early palliative care delivery for patients with dementia and respiratory failure, in particular in surgical and neurologic ICU settings.

Gastrodin regulates the TLR4/TRAF6/NF-κB pathway to reduce neuroinflammation and microglial activation in an AD model

BACKGROUND

Gastrodia elata (Orchidaceae) is a medicinal plant used in traditional Chinese medicine. The rhizomes contain numerous active components, of which Gastrodin (p-hydroxymethylphenyl-B-D-glucopyranoside) forms the basis of the traditional medicine Gastrodiae Rhizoma. Gastrodin is also found in other medicinal plants and has neuroprotective, antioxidant, and anti-inflammatory effects. Neuroinflammation plays a crucial role in neurodegeneration. Research indicates that consuming meals and drinks containing Gastrodiaelata can enhance cognitive functioning and memory in elderly patients. The mechanisms relevant to the problem have not been completely understood.

PURPOSE

The aim was to examine the in vivo and in vitro anti-neuroinflammatory effects of Gastrodin.

STUDY DESIGN

The neuroprotective effects of Gastrodin on the TLR4/TRAF6/NF-κB pathway and Stat3 phosphorylation in LPS-treated C57BL/6 mice and BV-2 cells were investigated.

METHODS

1. C57BL/6 mice were assigned to model, gastrodin, donepezil, and control groups (n = 10 per group). The Gastrodin group received 100 mg/kg/d for five days, and the Dopenezil group 1.3 mg/kg/d. A neuroinflammation model was established by administering intraperitoneal injections of 2 mg/kg LPS to all groups, excluding the control. To induce microglial activation in Gastrodin-treated mouse microglial BV-2 cells, 1 µg/ml LPS was introduced for 24 h Morris water mazes were utilized to evaluate learning and spatial memory. Expression and subcellular localization of TLR4/TRAF6/NF-κB axis-related proteins and p-Stat3, Iba-1, GFAP, iNOS, and CD206 were assessed by immunofluorescence, western blots, and ELISA. qRT-PCR was performed to determine and measure IL-1β, TNF-α, cell migration, and phagocytosis. Overexpression of TRAF6 was induced by transfection, and the effect of Gastrodin on IL-1β and p-NF-κB p65 levels was assessed.

RESULTS

1. In mice, gastrodin treatment mitigated LPS-induced deficits in learning and spatial memory, as well as reducing neuroinflammation in the hippocampus, expression of TLR4/TRAF6/NF-κB pathway proteins, activation of microglia and astrocytes, and phosphorylation of Stat3. 2. Gastrodin pretreatment improved LPS-induced inflammation in vitro, reducing expression of TLR4/TRAF6/NF-κB-associated proteins and p-Stat3, inducing microglial transformation from M1 to M2, and inhibiting migration and phagocytosis. Overexpression of TRAF6 inhibited the Gastrodin-induced effects.

CONCLUSION

Gastrodin suppresses neuroinflammation and microglial activation by modifying the TLR4/TRAF6/NF-κB pathway and Stat3 phosphorylation.

Exploring the significance of lipids in Alzheimer's disease and the potential of extracellular vesicles

Lipids play a significant role in maintaining central nervous system (CNS) structure and function, and the dysregulation of lipid metabolism is known to occur in many neurological disorders, including Alzheimer's disease. Here we review what is currently known about lipid dyshomeostasis in Alzheimer's disease. We propose that small extracellular vesicle (sEV) lipids may provide insight into the pathophysiology and progression of Alzheimer's disease. This stems from the recognition that sEV likely contributes to disease pathogenesis, but also an understanding that sEV can serve as a source of potential biomarkers. While the protein and RNA content of sEV in the CNS diseases have been studied extensively, our understanding of the lipidome of sEV in the CNS is still in its infancy.

Oligomeric amyloid beta prevents myelination in a clusterin-dependent manner

BACKGROUND

White matter loss is a well-documented phenomenon in Alzheimer's disease (AD) patients that has been recognized for decades. However, the underlying reasons for the failure of oligodendrocyte progenitor cells (OPCs) to repair myelin deficits in these patients remain elusive. A single nucleotide polymorphism (SNP) in Clusterin has been identified as a risk factor for late-onset Alzheimer's disease and linked to a decrease in white matter integrity in healthy adults, but its specific role in oligodendrocyte function and myelin maintenance in Alzheimer's disease pathology remains unclear.

METHODS

To investigate the impact of Clusterin on OPCs in the context of Alzheimer's disease, we employed a combination of immunofluorescence and transmission electron microscopy techniques, primary culture of OPCs, and an animal model of Alzheimer's disease.

RESULTS

Our findings demonstrate that Clusterin, a risk factor for late-onset AD, is produced by OPCs and inhibits their differentiation into oligodendrocytes. Specifically, we observed upregulation of Clusterin in OPCs in the 5xFAD mouse model of AD. We also found that the phagocytosis of debris, including amyloid beta (Aβ), myelin, and apoptotic cells leads to the upregulation of Clusterin in OPCs. In vivo experiments confirmed that Aβ oligomers stimulate Clusterin upregulation and that OPCs are capable of phagocytosing Aβ. Furthermore, we discovered that Clusterin significantly inhibits OPC differentiation and hinders the production of myelin proteins. Finally, we demonstrate that Clusterin inhibits OPC differentiation by reducing the production of IL-9 by OPCs.

CONCLUSION

Our data suggest that Clusterin may play a key role in the impaired myelin repair observed in AD and could serve as a promising therapeutic target for addressing AD-associated cognitive decline.

Association Between Oral Health and Cognitive Impairment in Older Adults: Insights from a Six-Year Prospective Cohort Study

OBJECTIVE

This study aims to investigate the relationships between four baseline oral conditions (periodontal status, dental caries, tooth wear, and dentition) and repeated global cognition or domain-specific cognition (memory, executive function, attention, and verbal fluency) in non-demented older adults over time.

METHODS

This prospective cohort study (2011-2019) enrolled 516 non-demented community-dwelling older adults (age ≥ 65) to explore the association between oral health and cognitive function. Global and domain-specific cognition were assessed biennially (four repeats) using a battery of neuropsychological tests. The baseline oral health conditions were examined, including periodontal status, dental caries, tooth wear, and dentition. The association of these oral conditions with cognition was evaluated by generalized linear mixed models. Stratified analyses were performed by important covariates.

RESULTS

Over time, dental caries was associated with poor memory in two different logical memory tests (β^= -0.06 and β^= -0.04). Incomplete dentition with less than 28 teeth was associated with poor performance in attention (β^= -0.05) and verbal fluency (β^= -0.03). These associations became more evident in those with an elevated inflammatory marker (IL-6, β^= -0.11 to -0.08). In contrast, tooth wear was associated with better memory in two different logical memory tests (β^= 0.33 and β^= 0.36) and better executive function (β^= 0.06) over time, and this association became more evident in those with the lowest inflammatory marker (IL-6, β^= 0.10).

CONCLUSIONS

Dental caries and incomplete dentition were associated with poor memory, attention, and verbal fluency performance. Conversely, tooth wear was associated with better memory performance and executive function.

CLINICAL SIGNIFICANCE

For early prevention of dementia, an evaluation of multiple dental and periodontal status in older adults helps predict the risk of dementia in the preclinical phase. Maintaining intact tooth structure without caries progression and eventually tooth loss may help prevent the worsening of memory, attention, and verbal fluency over time.

Smoking Impacts Alzheimer's Disease Progression Through Oral Microbiota Modulation

Alzheimer's disease (AD) is an important public health challenge with a limited understanding of its pathogenesis. Smoking is a significant modifiable risk factor for AD progression, and its specific mechanism is often interpreted from a toxicological perspective. However, microbial infections also contribute to AD, with oral microbiota playing a crucial role in its progression. Notably, smoking alters the ecological structure and pathogenicity of the oral microbiota. Currently, there is no systematic review or summary of the relationship between these three factors; thus, understanding this association can help in the development of new treatments. This review summarizes the connections between smoking, AD, and oral microbiota from existing research. It also explores how smoking affects the occurrence and development of AD through oral microbiota, and examines treatments for oral microbiota that delay the progression of AD. Furthermore, this review emphasizes the potential of the oral microbiota to act as a biomarker for AD. Finally, it considers the feasibility of probiotics and oral antibacterial therapy to expand treatment methods for AD.

Auditory Processing but Not Peripheral Hearing Differs Between Older Adults With and Without Mild Cognitive Impairment

PURPOSE

Impairments of hearing and auditory processing (AP) have been indicated as risk factors for dementia, but it remains unclear if persons with clinically diagnosed mild cognitive impairment (MCI) show such impairments. The objective of these analyses was to compare AP between those with and without a clinical diagnosis of MCI using a battery of AP measures.

METHOD

Data from 274 older adults from the Keys to Staying Sharp randomized clinical trial (NCT03528486) were analyzed. A battery of AP measures in which three domains (temporal processing, binaural processing, and degraded speech understanding) were addressed by six tests was administered. Analyses were registered at https://osf.io/nga4v.

RESULTS

Those with and without a clinical diagnosis of MCI differed significantly in age, p = .002; pure-tone hearing in the left ear, p = .007; sex, p = .015; and race, p < .001. These covariates were included in multivariate analysis of covariance, which indicated significant differences between persons with and without MCI on measures of binaural processing (ps ≤ .006), but not on measures of temporal processing or degraded speech (ps ≥ .093). Pure-tone hearing averages did not significantly differ among those with or without MCI after adjusting for age, sex, and race (ps ≥ .292).

CONCLUSIONS

AP in the binaural domain is impaired in MCI, but peripheral hearing did not significantly differ between those with and without MCI. Poor performance on AP measures of binaural processing may reflect problems dividing attention and may be indicative of dementia risk. Results have clinical implications for early detection of and intervention for cognitive impairment.

Caffeoylquinic Acid Mitigates Neuronal Loss and Cognitive Decline in 5XFAD Mice Without Reducing the Amyloid-β Plaque Burden

Background

Caffeoylquinic acid (CQA), which is abundant in coffee beans and Centella asiatica, reportedly improves cognitive function in Alzheimer's disease (AD) model mice, but its effects on neuroinflammation, neuronal loss, and the amyloid-β (Aβ) plaque burden have remained unclear.

Objective

To assess the effects of a 16-week treatment with CQA on recognition memory, working memory, Aβ levels, neuronal loss, neuroinflammation, and gene expression in the brains of 5XFAD mice, a commonly used mouse model of familial AD.

Methods

5XFAD mice at 7 weeks of age were fed a 0.8% CQA-containing diet for 4 months and then underwent novel object recognition (NOR) and Y-maze tests. The Aβ levels and plaque burden were analyzed by enzyme-linked immunosorbent assay and immunofluorescent staining, respectively. Immunostaining of markers of mature neurons, synapses, and glial cells was analyzed. AmpliSeq transcriptome analysis and quantitative reverse-transcription-polymerase chain reaction were performed to assess the effect of CQA on gene expression levels in the cerebral cortex of the 5XFAD mice.

Results

CQA treatment for 4 months improved recognition memory and ameliorated the reduction of mature neurons and synaptic function-related gene mRNAs. The Aβ levels, plaque burden, and glial markers of neuroinflammation seemed unaffected.

Conclusions

These findings suggest that CQA treatment mitigates neuronal loss and improves cognitive function without reducing Aβ levels or neuroinflammation. Thus, CQA is a potential therapeutic compound for AD, improving cognitive function via as-yet unknown mechanisms independent of reductions in Aβ or neuroinflammation.

Sensitivity of substrate translocation in chaperone-mediated autophagy to Alzheimer's disease progression

Alzheimer's disease (AD) is a progressive brain disorder marked by abnormal protein accumulation and resulting proteotoxicity. This study examines Chaperone-Mediated Autophagy (CMA), particularly substrate translocation into lysosomes, in AD. The study observes: (1) Increased substrate translocation activity into lysosomes, vital for CMA, aligns with AD progression, highlighted by gene upregulation and more efficient substrate delivery. (2) This CMA phase strongly correlates with AD's clinical symptoms; more proteotoxicity links to worse dementia, underscoring the need for active degradation. (3) Proteins like GFAP and LAMP2A, when upregulated, almost certainly indicate AD risk, marking this process as a significant AD biomarker. Based on these observations, this study proposes the following hypothesis: As AD progresses, the aggregation of pathogenic proteins increases, the process of substrate entry into lysosomes via CMA becomes active. The genes associated with this process exhibit heightened sensitivity to AD. This conclusion stems from an analysis of over 10,000 genes and 363 patients using two AI methodologies. These methodologies were instrumental in identifying genes highly sensitive to AD and in mapping the molecular networks that respond to the disease, thereby highlighting the significance of this critical phase of CMA.

Adapting a Dutch Web-Based Intervention to Support Family Caregivers of People With Dementia in the UK Context: Accelerated Experience-Based Co-Design

BACKGROUND

Around 700,000 family caregivers provide unpaid care for 900,000 people living with dementia in the United Kingdom. Few family caregivers receive support for their own psychological needs and funding for community respite services has declined. These trends are seen across Europe as demographic and budgetary pressures have intensified due to public spending cuts arising from the 2008 financial crisis and the COVID-19 pandemic. The World Health Organization has prioritized the need to expand the provision of support for caregivers and families of people with dementia by 2025. Web-based interventions have the potential for development as they require modest investment and can be accessed by family caregivers at home. Further cost benefits can be realized by adapting existing interventions with demonstrated effectiveness for new contexts. This paper reports initial findings from the CareCoach study, which is adapting Partner in Balance (PiB), a web-based coaching intervention developed in the Netherlands, for family caregivers in the United Kingdom.

OBJECTIVE

This study aims to work with unpaid family caregivers and staff in adapting the Dutch web-based support tool PiB to improve its acceptability and usability for use in the United Kingdom.

METHODS

Accelerated Experience-Based Co-Design (AEBCD) was used with caregivers, staff, and core stakeholders. Interviews, workshops, and stakeholder consultations were conducted. Data were analyzed iteratively. Recommendations for the redesign of PiB for use across the United Kingdom were adjudicated by the study Adaptation Working Party.

RESULTS

Sixteen caregivers and 17 staff took part in interviews. Thirteen caregivers and 17 staff took part in workshops. Most (n=26) participants were White, female, and retired. All except 4 caregivers (2 male and 2 female) found the PiB's offer of web-based self-help learning acceptable. Caregivers identified complexity and lack of inclusivity in some wording and video resources as problematic. The staff took a stronger perspective on the lack of inclusivity in PiB video resources. Staff and caregivers coproduced new inclusive wording and recommended creating new videos to adapt PiB for the UK context.

CONCLUSIONS

AEBCD methods facilitated the engagement of caregivers and staff and advanced the adaptation of the PiB complex intervention. An important addition to the AEBCD method in this process was the work of an Adaptation Working Party, which adjudicated and agreed to new wording where this could not be established in consultation with caregivers and staff.

TRIAL REGISTRATION

ISRCTN Registry ISRCTN12540555; https://doi.org/10.1186/ISRCTN12540555.

Association between chronic pain and dementia: a systematic review and meta-analysis

PURPOSE

Dementia and chronic pain (CP) are prevalent among older adults. However, no study has systematically reviewed the association between dementia and CP. Therefore, we performed this study to gather evidence about the potential relationship between the two.

METHODS

Two authors independently searched PubMed, Embase, and Web of Science to identify all records published up to 1 September 2022 that explored the association between CP and dementia. The methodological quality of the studies was assessed using the Newcastle Ottawa Scale (NOS). A fixed or random-effects model was used to pool the risk estimates.

RESULTS

Among the initial 3296 articles retrieved, 19 were included in the review (1 cross-sectional, and 18 cohort). The pooled result showed the risk of dementia was 1.42 times higher in CP patients (HR = 1.42, 95% CI 1.23-1.64, P < 0.001). dementia and CP subtypes, gender, and age did not significantly affect the results.

CONCLUSION

Our study shows that people who suffered from CP are at an increased risk of developing dementia, regardless of gender, age, and dementia and CP subtypes.

Sex-differences in the association of social health and marital status with blood-based immune and neurodegeneration markers in a cohort of community-dwelling older adults

BACKGROUND

The immune system has been proposed to play a role in the link between social health and all-cause dementia risk. We explored cross-sectional and longitudinal associations between social health, immune system balance and plasma neurodegeneration markers in community-dwelling older adults, and explored whether the balance between innate and adaptive immunity mediates associations between social health and both cognition and total brain volume.

METHODS

Social health markers (social support, marital status, loneliness) were measured in the Rotterdam Study between 2002-2008. Immune system cell counts and balance were assessed repeatedly from 2002 to 2016 using white blood-cell-based indices and individual counts (granulocyte-to-lymphocyte ratio (GLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII)). Plasma neurodegeneration biomarkers (amyloid-β40, amyloid-β42, total tau and neurofilament light chain) were measured once from blood samples collected between 2002-2008. Global cognitive function and total brain volume (MRI) were measured at the follow-up visit between 2009-2014. We used linear mixed models to study longitudinal associations and performed causal mediation analyses.

RESULTS

In 8374 adults (mean age 65.7, 57 % female), never married participants (n = 394) had higher GLR, PLR and SII compared to married peers at baseline and during follow-up, indicating imbalance towards innate immunity. Being never married was associated with higher plasma amyloid-β40, and being widowed or divorced with higher plasma total tau levels at baseline. Widowed or divorced males, but not females, had higher GLR, PLR and SII at baseline. Higher social support was associated with lower PLR in females, but higher PLR in males. Loneliness was not associated with any of the immune system balance ratios. Never married males had higher levels of all plasma neurodegeneration markers at baseline. Immune system balance did not mediate associations between social health and cognition or total brain volume, but does interact with marital status.

CONCLUSION

This study indicates that marital status is associated with blood-based immune system markers toward innate immunity and higher levels of plasma neurodegeneration markers. This is particularly evident for never married or previously married male older adults compared to married or female peers.

Social activities in multidomain dementia prevention interventions: insights from practice and a blueprint for the future

Introduction

Social activities are important for health and act as a driver of cognitive reserve during aging. In this perspective paper, we describe challenges and outline future (research) endeavors to establish better operationalization of social activities in multidomain interventions to prevent dementia.

Body

We first address the lack of conceptual clarity, which makes it difficult to measure engagement in social activities. Second, drawing from our experience with the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER), we discuss social activities in multidomain dementia prevention interventions. Using qualitative data from the Multimodal Preventive Trial for Alzheimer's Disease (MIND-ADmini), we reflect on participant experiences with social activities. Third, we address the potential and challenges of digital solutions in promoting social activities in interventions for dementia prevention. Finally, we share insights from a workshop on digital technology, where we consulted with individuals with and without cognitive impairment who have been involved in three European projects (i.e., EU-FINGERS, Multi-MeMo, and LETHE).

Discussion

Based on these insights, we advocate for research that strengthens and accelerates the integration of social activities into multidomain interventions for dementia prevention. We propose several ways to achieve this: (a) by conducting mixed methods research to formulate a broadly accepted definition and instructions to measure social activities; (b) by focusing on promoting engagement in social activities beyond the intervention setting; and (c) by exploring the needs and preferences of older adults towards digitally-supported interventions and co-design of new technologies that enrich in-person social activities.

Downregulation of miR-181c-5p in Alzheimer's disease weakens the response of microglia to Aβ phagocytosis

Alzheimer's disease (AD) is an age-associated neurodegenerative disease. Recently, studies have demonstrated the potential involvement of microRNA-181c-5p (miR-181c-5p) in AD. However, the mechanism through which miR-181c-5p is responsible for the onset and progression of this disease remains unclear, and our study aimed to explore this problem. Differential expression analysis of the AD dataset was performed to identify dysregulated genes. Based on hypergeometric analysis, AD differential the upstream regulation genes miR-181c-5p was found. We constructed a model where SH-SY5Y and BV2 cells were exposed to Aβ1-42 to simulate AD. Levels of tumor necrosis factor-alpha, interleukin-6, and IL-1β were determined using enzyme-linked immunosorbent assay or reverse transcription quantitative polymerase chain reaction. Phosphorylation levels of p-P38 and P38 were detected by Western blot. The level of apoptosis in BV2 cells under Aβ1-42 stress was exacerbated by miR-181c-5p mimic. Downregulated miR-181c-5p impaired the phagocytosis and degradation of Aβ by BV2 cells. The release of proinflammatory cytokines in BV2 cells with Aβ1-42 stress was alleviated by miR-181c-5p upregulation. Additionally, miR-181c-5p downregulation alleviated the phosphorylation of P38 in Aβ1-42-induced SH-SY5Y cells. In conclusion, miR-181c-5p improves the phagocytosis of Aβ by microglial cells in AD patients, thereby reducing neuroinflammation.

Unraveling the mechanistic interplay of mediators orchestrating the neuroprotective potential of harmine

Neurodegenerative diseases (NDDs) encompass a range of conditions characterized by the specific dysfunction and continual decline of neurons, glial cells, and neural networks within the brain and spinal cord. The majority of NDDs exhibit similar underlying causes, including oxidative stress, neuroinflammation, and malfunctioning of mitochondria. Elevated levels of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), alongside decreased expression of brain-derived neurotrophic factor (BDNF) and glutamate transporter subtype 1 (GLT-1), constitute significant factors contributing to the pathogenesis of NDDs. Additionally, the dual-specificity tyrosine phosphorylation-regulated kinase 1 A (DYRK1A) gene has emerged as a significant target for the treatment of NDDs at the preclinical level. It significantly contributes to developmental brain defects, early onset neurodegeneration, neuronal loss, and dementia in Down syndrome. Moreover, an impaired ubiquitin-proteosome system (UPS) also plays a pathological role in NDDs. Malfunctioning of UPS leads to abnormal protein buildup or aggregation of α-synuclein. α-Synuclein is a highly soluble unfolded protein that accumulates in Lewy bodies and Lewy neurites in Parkinson's disease and other synucleinopathies. Recent research highlights the promising potential of natural products in combating NDDs relative to conventional therapies. Alkaloids have emerged as promising candidates in the fight against NDDs. Harmine is a tricyclic β-carboline alkaloid (harmala alkaloid) with one indole nucleus and a six-membered pyrrole ring. It is extracted from Banisteria caapi and Peganum harmala L. and exhibits diverse pharmacological properties, encompassing neuroprotective, antioxidant, anti-inflammatory, antidepressant, etc. Harmine has been reported to mediate its neuroprotective via reducing the level of inflammatory mediators, NADPH oxidase, AChE, BChE and reactive oxygen species (ROS). Whereas, it has been observed to increase the levels of BDNF, GLT-1 and anti-oxidant enzymes, along with protein kinase-A (PKA)-mediated UPS activation. This review aims to discuss the mechanistic interplay of various mediators involved in the neuroprotective effect of harmine.

Urolithin A Inhibits Anterior Basolateral Amygdala to Ventral Hippocampal CA1 Circuit to Ameliorate Amyloid-β-Impaired Social Ability

Background

Anxiety and social withdrawal are highly prevalent among patients with Alzheimer's disease (AD). However, the neural circuit mechanisms underlying these symptoms remain elusive, and there is a need for effective prevention strategies.

Objective

This study aims to elucidate the neural circuitry mechanisms underlying social anxiety in AD.

Methods

We utilized 5xFAD mice and conducted a series of experiments including optogenetic manipulation, Tandem Mass Tag-labeled proteome analysis, behavioral assessments, and immunofluorescence staining.

Results

In 5xFAD mice, we observed significant amyloid-β (Aβ) accumulation in the anterior part of basolateral amygdala (aBLA). Behaviorally, 6-month-old 5xFAD mice displayed excessive social avoidance during social interaction. Concurrently, the pathway from aBLA to ventral hippocampal CA1 (vCA1) was significantly activated and exhibited a disorganized firing patterns during social interaction. By optogenetically inhibiting the aBLA-vCA1 pathway, we effectively improved the social ability of 5xFAD mice. In the presence of Aβ accumulation, we identified distinct changes in the protein network within the aBLA. Following one month of administration of Urolithin A (UA), we observed significant restoration of the abnormal protein network within the aBLA. UA treatment also attenuated the disorganized firings of the aBLA-vCA1 pathway, leading to an improvement in social ability.

Conclusions

The aBLA-vCA1 circuit is a vulnerable pathway in response to Aβ accumulation during the progression of AD and plays a crucial role in Aβ-induced social anxiety. Targeting the aBLA-vCA1 circuit and UA administration are both effective strategies for improving the Aβ-impaired social ability.

Genome-Wide DNA Methylation in Early-Onset-Dementia Patients Brain Tissue and Lymphoblastoid Cell Lines

Epigenetics, a potential underlying pathogenic mechanism of neurodegenerative diseases, has been in the scope of several studies performed so far. However, there is a gap in regard to analyzing different forms of early-onset dementia and the use of Lymphoblastoid cell lines (LCLs). We performed a genome-wide DNA methylation analysis on sixty-four samples (from the prefrontal cortex and LCLs) including those taken from patients with early-onset forms of Alzheimer's disease (AD) and frontotemporal dementia (FTD) and healthy controls. A beta regression model and adjusted p-values were used to obtain differentially methylated positions (DMPs) via pairwise comparisons. A correlation analysis of DMP levels with Clariom D array gene expression data from the same cohort was also performed. The results showed hypermethylation as the most frequent finding in both tissues studied in the patient groups. Biological significance analysis revealed common pathways altered in AD and FTD patients, affecting neuron development, metabolism, signal transduction, and immune system pathways. These alterations were also found in LCL samples, suggesting the epigenetic changes might not be limited to the central nervous system. In the brain, CpG methylation presented an inverse correlation with gene expression, while in LCLs, we observed mainly a positive correlation. This study enhances our understanding of the biological pathways that are associated with neurodegeneration, describes differential methylation patterns, and suggests LCLs are a potential cell model for studying neurodegenerative diseases in earlier clinical phases than brain tissue.

Trends and hotspots in tea and Alzheimer's disease research from 2014 to 2023: A bibliometric and visual analysis

Objectives

The positive effects of tea on Alzheimer's disease (AD) have increasingly captured researchers' attention. Nevertheless, the quantitative comprehensive analysis in the relevant literatur is lack. This paper aims to thoroughly examine the current research status and hotspots from 2014 to 2023, providing a valuable reference for subsequent research.

Methods

Documents spanning from 2014 to 2023 were searched from the Web of Science, and the R software, VOSviewer, and Citespace software were used for analysis and visualization.

Results

A total of 374 documents were contained in the study. The rate of article publications exhibited a consistent increase each year from 2014 to 2023. Notably, China emerged as the leading country in terms of published articles, followed by the United States and India. Simultaneously, China is also in a leading position in cooperation with other countries. Molecules emerged as the most frequently published journal, while the Journal of Alzheimer's Disease secured the top spot in terms of citations. The identified main keywords included oxidative stress, amyloid, epigallocatechin gallate, and green tea polyphenol, among others. These focal areas delved into the antioxidative and anti-amyloid aggregation actions of tea's polyphenolic components. Furthermore, the particularly way in which epigallocatechin gallate delivers neuroprotective outcomes by influencing molecules related to AD represents a focal point of research.

Conclusion

The increasing attention from researchers on the role of tea in ameliorating AD positions it as a hot spot in the development of anti-AD drugs in the development of future. Through our generalized analysis of the current landscape and hotspots regarding tea's application in AD, this study provides an estimable reference for future research endeavors.

Irisin inhibits microglial senescence via TFAM-mediated mitochondrial metabolism in a mouse model of tauopathy

BACKGROUND

The accumulation of senescent microglia has been highlighted as a critical contributor to the progression of tauopathies. Irisin, a muscle-derived hormone produced by the proteolytic cleavage of Fibronectin-domain III containing 5 (FNDC5), mediates the pleiotropic effects of exercise on the physical body. Herein, we investigate the potential role of irisin in microglial senescence in tauopathies.

METHODS

To model tauopathies both in vivo and in vitro, we utilized P301S tau transgenic mice and tau K18 fibril-treated microglia BV2 cells, respectively. We first examined the expression of the irisin expression and senescence phenotypes of microglia in tauopathies. Subsequently, we investigated the impact of irisin on microglial senescence and its underlying molecular mechanisms.

RESULT

We observed a reduction in irisin levels and an onset of premature microglial senescence both in vivo and in vitro. Irisin administration was found to counteract microglial senescence and ameliorate cognitive decline in P301S mice. Mechanistically, irisin effectively inhibited microglial senescence by stimulating the expression of mitochondrial transcription factor A (TFAM), a master regulator of mitochondrial respiratory chain biogenesis, thereby enhancing mitochondrial oxidative phosphorylation (OXPHOS). Silencing TFAM eliminated the inhibitory effect of irisin on microglial senescence as well as the restorative effect of irisin on mitochondrial OXPHOS. Furthermore, the SIRT1/PGC1α signaling pathway appeared to be implicated in irisin-mediated upregulation of TFAM.

CONCLUSION

Taken together, our study revealed that irisin mitigated microglial senescence via TFAM-driven mitochondrial biogenesis, suggesting a promising new avenue for therapeutic strategies targeting tauopathies.

Sex-specific mechanisms of cerebral microvascular BK Ca dysfunction in a mouse model of Alzheimer's disease

BACKGROUND

Cerebral microvascular dysfunction and nitro-oxidative stress are present in patients with Alzheimer's disease (AD) and may contribute to disease progression and severity. Large conductance Ca 2+ -activated K + channels (BK Ca ) play an essential role in vasodilatory responses and maintenance of myogenic tone in resistance arteries. BK Ca impairment can lead to microvascular dysfunction and hemodynamic deficits in the brain. We hypothesized that reduced BK Ca function in cerebral arteries mediates microvascular and neurovascular responses in the 5x-FAD model of AD.

METHODS

BK Ca activity in the cerebral microcirculation was assessed by patch clamp electrophysiology and pressure myography, in situ Ca 2+ sparks by spinning disk confocal microscopy, hemodynamics by laser speckle contrast imaging. Molecular and biochemical analyses were conducted by affinity-purification assays, qPCR, Western blots and immunofluorescence.

RESULTS

We observed that pial arteries from 5-6 months-old male and female 5x-FAD mice exhibited a hyper-contractile phenotype than wild-type (WT) littermates, which was linked to lower vascular BK Ca activity and reduced open probability. In males, BK Ca dysfunction is likely a consequence of an observed lower expression of the pore-forming subunit BKα and blunted frequency of Ca 2+ sparks, which are required for BK Ca activity. However, in females, impaired BK Ca function is, in part, a consequence of reversible nitro-oxidative changes in the BK α subunit, which reduces its open probability and regulation of vascular tone. We further show that BK Ca function is involved in neurovascular coupling in mice, and its dysfunction is linked to neurovascular dysfunction in the model.

CONCLUSION

These data highlight the central role played by BK Ca in cerebral microvascular and neurovascular regulation, as well as sex-dependent mechanisms underlying its dysfunction in a mouse model of AD.

Brain cholesterol and Alzheimer's disease: challenges and opportunities in probe and drug development

Cholesterol homeostasis is impaired in Alzheimer's disease; however, attempts to modulate brain cholesterol biology have not translated into tangible clinical benefits for patients to date. Several recent milestone developments have substantially improved our understanding of how excess neuronal cholesterol contributes to the pathophysiology of Alzheimer's disease. Indeed, neuronal cholesterol was linked to the formation of amyloid-β and neurofibrillary tangles through molecular pathways that were recently delineated in mechanistic studies. Furthermore, remarkable advances in translational molecular imaging have now made it possible to probe cholesterol metabolism in the living human brain with PET, which is an important prerequisite for future clinical trials that target the brain cholesterol machinery in Alzheimer's disease patients-with the ultimate aim being to develop disease-modifying treatments. This work summarizes current concepts of how the biosynthesis, transport and clearance of brain cholesterol are affected in Alzheimer's disease. Further, current strategies to reverse these alterations by pharmacotherapy are critically discussed in the wake of emerging translational research tools that support the assessment of brain cholesterol biology not only in animal models but also in patients with Alzheimer's disease.

Circulating sphingolipids and subclinical brain pathology: the cardiovascular health study

Background

Sphingolipids are implicated in neurodegeneration and neuroinflammation. We assessed the potential role of circulating ceramides and sphingomyelins in subclinical brain pathology by investigating their association with brain magnetic resonance imaging (MRI) measures and circulating biomarkers of brain injury, neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) in the Cardiovascular Health Study (CHS), a large and intensively phenotyped cohort of older adults.

Methods

Brain MRI was offered twice to CHS participants with a mean of 5 years between scans, and results were available from both time points in 2,116 participants (mean age 76 years; 40% male; and 25% APOE ε4 allele carriers). We measured 8 ceramide and sphingomyelin species in plasma samples and examined the associations with several MRI, including worsening grades of white matter hyperintensities and ventricular size, number of brain infarcts, and measures of brain atrophy in a subset with quantitative measures. We also investigated the sphingolipid associations with serum NfL and GFAP.

Results

In the fully adjusted model, higher plasma levels of ceramides and sphingomyelins with a long (16-carbon) saturated fatty acid were associated with higher blood levels of NfL [β = 0.05, false-discovery rate corrected P (PFDR) = 0.004 and β = 0.06, PFDR = < 0.001, respectively]. In contrast, sphingomyelins with very long (20- and 22-carbon) saturated fatty acids tended to have an inverse association with levels of circulating NfL. In secondary analyses, we found an interaction between ceramide d18:1/20:0 and sex (P for interaction = <0.001), such that ceramide d18:1/20:0 associated with higher odds for infarcts in women [OR = 1.26 (95%CI: 1.07, 1.49), PFDR = 0.03]. We did not observe any associations with GFAP blood levels, white matter grade, ventricular grade, mean bilateral hippocampal volume, or total brain volume.

Conclusion

Overall, our comprehensive investigation supports the evidence that ceramides and sphingomyelins are associated with increased aging brain pathology and that the direction of association depends on the fatty acid attached to the sphingosine backbone.

Portuguese Caregivers of Persons With Alzheimer's Disease in the Context of the COVID-19 Pandemic: A Qualitative Study of the Grieving Process

This study addresses the experiences of informal caregivers caring for elderly family members with Alzheimer's disease (AD) during the COVID-19 pandemic. The study includes a sample of eight informal caregivers who were evaluated through a semi-structured interview six months after the death of a loved one they cared for. A thematic content analysis was applied to the interviews and yielded two higher-order domains: (1) Experiencing the AD and the death of a family member and (2) The grieving process during the COVID-19 pandemic. The results provide valuable insights into family caregivers' experiences regarding the profound emotional impact of caregiving and grief during the COVID-19 pandemic. Caregivers maintain their identity even after loss, underscoring the enduring impact of caregiving. The identity as a caregiver impacted coping and grief responses, highlighting the need for tailored interventions.

Potential Effects of Traditional Chinese Medicine in Anti-Aging and Aging-Related Diseases: Current Evidence and Perspectives

Aging and aging-related diseases present a global public health problem. Therefore, the development of efficient anti-aging drugs has become an important area of research. Traditional Chinese medicine is an important complementary and alternative branch of aging-related diseases therapy. Recently, a growing number of studies have revealed that traditional Chinese medicine has a certain delaying effect on the progression of aging and aging-related diseases. Here, we review the progress in research into using traditional Chinese medicine for aging and aging-related diseases (including neurodegenerative diseases, cardiovascular diseases, diabetes, and cancer). Furthermore, we summarize the potential mechanisms of action of traditional Chinese medicine and provide references for further studies on aging and aging-related diseases.

P2X7 Receptor: an Emerging Target in Alzheimer's Disease

Alzheimer's disease (AD) is a major cause of age-related dementia, which is becoming a global health crisis. However, the pathogenesis and etiology of AD are still not fully understood. And there are no valid treatment methods or precise diagnostic tools for AD. There is increasing evidence that P2X7R expression is upregulated in AD and is involved in multiple related pathological processes such as Aβ plaques, neurogenic fiber tangles, oxidative stress, and chronic neuroinflammation. This suggests that P2X7R may be a key player in the development of AD. P2X7R is a member of the ligand-gated purinergic receptor (P2X) family. It has received attention in neuroscience due to its role in a wide range of aging and age-related neurological disorders. In this review, we summarize current information on the roles of P2X7R in AD and suggest potential pharmacological interventions to slow down AD progression.

Lifetime adversity predicts depression, anxiety, and cognitive impairment in a nationally representative sample of older adults in the United States

OBJECTIVE

Although life stress and adversity are well-known risk factors for mental health problems and cognitive impairment among older adults, limited research has comprehensively examined the impact of both childhood and adulthood adversity on psychiatric and cognitive impairment symptoms over a prolonged period. To address this issue, we investigated how lifetime adversity exposure is related to symptoms of depression, anxiety, and cognitive impairment in a nationally representative, longitudinal sample of older adults in the United States.

METHOD

We analyzed data from the Health and Retirement Study (1992-2016). The sample included 3496 individuals (59.9% female), aged ≥64 years old (Mage = 76.0 ± 7.6 years in 2016). We used the individual-level panel data and ordinary least squares regressions to estimate associations between childhood and adulthood adversities, and later-life depression, anxiety, and cognitive impairment.

RESULTS

Many participants experienced a significant early life (38%) or adulthood (79%) stressor. Moreover, experiencing one childhood adversity (vs. none) was associated with a 17.4% increased risk of adulthood adversity. Finally, as hypothesized, childhood adversity exposure was related to experiencing more depression and anxiety symptoms in later life, whereas adulthood stressor exposure predicted more cognitive impairment as well as more depression and anxiety symptoms.

DISCUSSION

These findings demonstrate significant associations between lifetime adversity and symptoms of depression, anxiety, and cognitive impairment in older adults. Screening for lifetime stressors may thus help healthcare professionals and policymakers identify individuals who could potentially benefit from interventions designed to reduce stress and enhance resilience.

Increased community engagement of Indigenous Peoples in dementia research leads to higher context relevance of results

INTRODUCTION

Health research that focuses on Indigenous Peoples must ensure that the community in question is actively engaged, and that the results have context relevance for Indigenous Peoples. Context relevance is "the benefits, usability, and respectful conduct of research from the perspective of Indigenous communities." The purpose of this study was to apply two tools within an already-published scoping review of 76 articles featuring research on cognitive impairment and dementia among Indigenous Peoples worldwide. One tool assessed levels of community engagement reported in the corpus, and the other tool assessed the context relevance of recommendations in the corpus. We hypothesized that research with higher levels of reported community engagement would produce recommendations with greater context relevance for Indigenous Peoples.

METHODS

We employed semi-structured deductive coding using two novel tools assessing levels of reported community engagement and context relevance of recommendations based on studies included in the existing scoping review.

RESULTS

Application of the two tools revealed a positive relationship between increasing community engagement and greater context relevance. Community engagement primarily occurred in studies conducted with First Nations, Inuit, and Métis populations in Canada and with Australian Aboriginal and/or Torres Strait Islander Peoples. Research with Alaska Native, American Indian, and Native Hawaiian Peoples in the USA stood out for its comparative lack of meaningful community engagement.

DISCUSSION

There is opportunity to utilize these tools, and the results of this assessment, to enhance training and mentorship for researchers who work with Indigenous populations. There is a need to increase investigator capacity to involve communities throughout all phases of research, particularly in the pre-research stages.

Crocin ameliorates neuroinflammation and cognitive impairment in mice with Alzheimer's disease by activating PI3K/AKT pathway

BACKGROUND

Crocin has a good prospect in the treatment of Alzheimer's disease (AD), but the mechanisms underlying its neuroprotective effects remain elusive. This study aimed to investigate the neuroprotective effects of Crocin and its underlying mechanisms in AD.

METHODS

AD mice were set up by injecting Aβ25-35 solution into the hippocampus. Then, the AD mice were injected intraperitoneally with 40 mg/kg/day of Crocin for 14 days. Following the completion of Crocin treatment, an open-field test, Y-maze test and Morris water maze test were conducted to evaluate the impact of Crocin on spatial learning and memory deficiency in mice. The effects of Crocin on hippocampal neuron injury, proinflammatory cytokine expressions (IL-1β, IL-6, and TNF-α), and PI3K/AKT signaling-related protein expressions were measured using hematoxylin and eosin staining, Western blot, and quantitative real-time polymerase chain reaction (qRT-PCR) experiments, respectively.

RESULTS

Crocin attenuated Aβ25-35-induced spatial learning and memory deficiency and hippocampal neuron injury. Furthermore, the Western blot and qRT-PCR results showed that Crocin effectively suppressed inflammation and activated the PI3K/AKT pathway in Aβ25-35-induced mice.

CONCLUSION

Crocin restrained neuroinflammation via the activation of the PI3K/AKT pathway, thereby ameliorating the cognitive dysfunction of AD mice.

Liraglutide versus pramlintide in protecting against cognitive function impairment through affecting PI3K/AKT/GSK-3β/TTBK1 pathway and decreasing Tau hyperphosphorylation in high-fat diet- streptozocin rat model

The American Diabetes Association guidelines (2021) confirmed the importance of raising public awareness of diabetes-induced cognitive impairment, highlighting the links between poor glycemic control and cognitive impairment. The characteristic brain lesions of cognitive dysfunction are neurofibrillary tangles (NFT) and senile plaques formed of amyloid-β deposition, glycogen synthase kinase 3 beta (GSK3β), and highly homologous kinase tau tubulin kinase 1 (TTBK1) can phosphorylate Tau proteins at different sites, overexpression of these enzymes produces extensive phosphorylation of Tau proteins making them insoluble and enhance NFT formation, which impairs cognitive functions. The current study aimed to investigate the potential contribution of liraglutide and pramlintide in the prevention of diabetes-induced cognitive dysfunction and their effect on the PI3K/AKT/GSK-3β/TTBK1 pathway in type 2 diabetic (T2D) rat model. T2D was induced by administration of a high-fat diet for 10 weeks, then injection of a single dose of streptozotocin (STZ); treatment was started with either pramlintide (200 μg/kg/day sc) or liraglutide (0.6 mg/kg/day sc) for 6 weeks in addition to the HFD. At the end of the study, cognitive functions were assessed by novel object recognition and T-maze tests. Then, rats were sacrificed for biochemical and histological assessment of the hippocampal tissue. Both pramlintide and liraglutide treatment revealed equally adequate control of diabetes, prevented the decline in memory function, and increased PI3K/AKT expression while decreasing GSK-3β/TTBK1 expression; however, liraglutide significantly decreased the number of Tau positive cells better than pramlintide did. This study confirmed that pramlintide and liraglutide are promising antidiabetic medications that could prevent associated cognitive disorders in different mechanisms.

Serotonergic dysfunction may mediate the relationship between alcohol consumption and Alzheimer's disease

The impact of Alzheimer's disease (AD) and its related dementias is rapidly expanding, and its mitigation remains an urgent social and technical challenge. To date there are no effective treatments or interventions for AD, but recent studies suggest that alcohol consumption is correlated with the risk of developing dementia. In this review, we synthesize data from preclinical, clinical, and epidemiological models to evaluate the combined role of alcohol consumption and serotonergic dysfunction in AD, underscoring the need for further research on this topic. We first discuss the limitations inherent to current data-collection methods, and how neuropsychiatric symptoms common among AD, alcohol use disorder, and serotonergic dysfunction may mask their co-occurrence. We additionally describe how excess alcohol consumption may accelerate the development of AD via direct effects on serotonergic function, and we explore the roles of neuroinflammation and proteostasis in mediating the relationship between serotonin, alcohol consumption, and AD. Lastly, we argue for a shift in current research to disentangle the pathogenic effects of alcohol on early-affected brainstem structures in AD.

Association of Tumor Necrosis Factor-α Inhibitors with Incident Dementia: Analysis Based on Population-Based Cohort Studies

BACKGROUND AND OBJECTIVE

Preliminary evidence suggests a possible preventive effect of tumor necrosis factor-α inhibitors (TNFi) on incident dementia. The objective of the analysis was to investigate the association between TNFi and the risk of incident dementia in a population undergoing treatment for rheumatological disorders.

METHODS

We followed patients aged ≥ 65 years with dementia and rheumatological conditions in two cohort studies, DANBIO (N = 21,538), a Danish clinical database, and AOK PLUS (N = 7112), a German health insurance database. We defined incident dementia using diagnostic codes and/or medication use and used Cox regression to compare the associations of TNFi with other rheumatological therapies on the risk of dementia. To ensure that the patients were receiving long-term medication, we included patients with rheumatic diseases and systemic therapies.

RESULTS

We observed similar trends towards a lower risk of dementia associated with TNFi versus other anti-inflammatory agents in both cohorts (hazard ratios were 0.92 [95% confidence interval 0.76, 1.10] in DANBIO and 0.89 [95% confidence interval 0.63, 1.24] in AOK PLUS, respectively).

CONCLUSIONS

Tumor necrosis factor-α inhibitors may decrease the risk of incident dementia although the association did not reach statistical significance in this analysis. Further research, ideally with randomization, is needed to gauge the potential of repurposing TNFi for dementia prevention and/or treatment.

Genetic-based patient stratification in Alzheimer's disease

Alzheimer's disease (AD) shows a high pathological and symptomatological heterogeneity. To study this heterogeneity, we have developed a patient stratification technique based on one of the most significant risk factors for the development of AD: genetics. We addressed this challenge by including network biology concepts, mapping genetic variants data into a brain-specific protein-protein interaction (PPI) network, and obtaining individualized PPI scores that we then used as input for a clustering technique. We then phenotyped each obtained cluster regarding genetics, sociodemographics, biomarkers, fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging, and neurocognitive assessments. We found three clusters defined mainly by genetic variants found in MAPT, APP, and APOE, considering known variants associated with AD and other neurodegenerative disease genetic architectures. Profiling of these clusters revealed minimal variation in AD symptoms and pathology, suggesting different biological mechanisms may activate the neurodegeneration and pathobiological patterns behind AD and result in similar clinical and pathological presentations, even a shared disease diagnosis. Lastly, our research highlighted MAPT, APP, and APOE as key genes where these genetic distinctions manifest, suggesting them as potential targets for personalized drug development strategies to address each AD subgroup individually.

Insights into designing educational materials for persons living with dementia: a focus group study

BACKGROUND

Persons living with dementia (PLWD) may experience communication difficulties that impact their ability to process written and pictorial information. Patient-facing education may help promote discontinuation of potentially inappropriate medications for older adults without dementia, but it is unclear how to adapt this approach for PLWD. Our objective was to solicit feedback from PLWD and their care partners to gain insights into the design of PLWD-facing deprescribing intervention materials and PLWD-facing education material more broadly.

METHODS

We conducted 3 successive focus groups with PLWD aged ≥ 50 (n = 12) and their care partners (n = 10) between December 2022 and February 2023. Focus groups were recorded and transcripts were analyzed for overarching themes.

RESULTS

We identified 5 key themes: [1] Use images and language consistent with how PLWD perceive themselves; [2] Avoid content that might heighten fear or anxiety; [3] Use straightforward delivery with simple language and images; [4] Direct recipients to additional information; make the next step easy; and [5] Deliver material directly to the PLWD.

CONCLUSION

PLWD-facing educational material should be addressed directly to PLWD, using plain, non-threatening and accessible language with clean, straightforward formatting.

Understanding treatment goals and their application in clinical trial design for patients with Alzheimer disease and caregivers

Background

As research continues towards improved treatments for Alzheimer disease (AD), there is growing interest in the views and needs from patients and caregivers on AD treatments.

Methods

In this study, we surveyed patients with AD and caregivers to determine the treatment goals that are most important to them. Patients with AD and caregivers were independently recruited in Europe and North America to complete a web-based survey. Eligible participants were ≥18 years old and diagnosed with mild cognitive impairment or mild-to-moderate AD (patient-reported group) or persons involved in the care of patients with AD (caregiver-reported group). A total of 322 patients and 614 caregivers completed the survey.

Results

The demographic characteristics of patients in the patient-reported and the caregiver-reported groups were similar. Disease severity of patients was greater in the caregiver-reported group compared with the patient-reported group (72.1% versus 46.9% moderate AD). The most important goal of AD treatment in both groups was maintenance of quality of life (QoL) (patient-reported group 31.1% and caregiver-reported group 38.8%; p=0.01). This was consistent across disease stages or symptom severity except for patients with mild cognitive impairment in the caregiver-reported group where slowing the progression of memory loss was the most important treatment goal.

Conclusions

Patient QoL was consistently the most relevant treatment goal for patients with AD and caregivers. In AD clinical trials, patient-relevant outcomes, for example, QoL, should be given high priority to reflect the needs and demands of patients with AD and their caregivers.A preliminary report of this work was presented at the 14th Clinical Trials on Alzheimer's Disease meeting (November 9-12, 2021).

Predicting Risk of Alzheimer's Diseases and Related Dementias with AI Foundation Model on Electronic Health Records

Early identification of Alzheimer's disease (AD) and AD-related dementias (ADRD) has high clinical significance, both because of the potential to slow decline through initiating FDA-approved therapies and managing modifiable risk factors, and to help persons living with dementia and their families to plan before cognitive loss makes doing so challenging. However, substantial racial and ethnic disparities in early diagnosis currently lead to additional inequities in care, urging accurate and inclusive risk assessment programs. In this study, we trained an artificial intelligence foundation model to represent the electronic health records (EHR) data with a vast cohort of 1.2 million patients within a large health system. Building upon this foundation EHR model, we developed a predictive Transformer model, named TRADE, capable of identifying risks for AD/ADRD and mild cognitive impairment (MCI), by analyzing the past sequential visit records. Amongst individuals 65 and older, our model was able to generate risk predictions for various future timeframes. On the held-out validation set, our model achieved an area under the receiver operating characteristic (AUROC) of 0.772 (95% CI: 0.770, 0.773) for identifying the AD/ADRD/MCI risks in 1 year, and AUROC of 0.735 (95% CI: 0.734, 0.736) in 5 years. The positive predictive values (PPV) in 5 years among individuals with top 1% and 5% highest estimated risks were 39.2% and 27.8%, respectively. These results demonstrate significant improvements upon the current EHR-based AD/ADRD/MCI risk assessment models, paving the way for better prognosis and management of AD/ADRD/MCI at scale.

Mechanical Ventilation in Older Adults With Dementia: Opportunities to Promote Goal-Concordant Care

CONTEXT

Recent studies show increasing use of mechanical ventilation among people living with dementia. There are concerns that this trend may not be driven by patient preferences.

OBJECTIVES

To better understand decision-making regarding mechanical ventilation in people living with dementia.

METHODS

This was an electronic health record-based retrospective cohort study of older adults with dementia (n = 295) hospitalized at one of two teaching hospitals between 2015 and 2019 who were supported with mechanical ventilation (n = 191) or died without mechanical ventilation (n = 104). Multivariable logistic regression was used to examine associations between patient characteristics and mechanical ventilation use.

RESULTS

The median age was 78 years (IQR 71-86), 41% were female, 28% resided in a nursing home, and 58% had clinical markers of advanced dementia (dehydration, weight loss, mobility limitations, or pressure ulcers). Among patients supported with mechanical ventilation, 70% were intubated within 24 hours of presentation, including 31% intubated before hospital arrival. Younger age, higher illness acuity, and absence of a treatment-limiting Physician Orders for Life-Sustaining Treatment document were associated with mechanical ventilation use; nursing home residence and clinical markers of advanced dementia were not. Most patients (89%) had a documented goals of care discussion (GOCD) during hospitalization.

CONCLUSION

Future efforts to promote goal-concordant care surrounding mechanical ventilation use for people living with dementia should involve identifying barriers to goal-concordant care in pre-hospital settings, assessing the timeliness of in-hospital GOCD, and developing strategies for in-the-moment crisis communication across settings.

Association of whole-person eigen-polygenic risk scores with Alzheimer's disease

Late-Onset Alzheimer's Disease (LOAD) is a heterogeneous neurodegenerative disorder with complex etiology and high heritability. Its multifactorial risk profile and large portions of unexplained heritability suggest the involvement of yet unidentified genetic risk factors. Here we describe the "whole person" genetic risk landscape of polygenic risk scores for 2218 traits in 2044 elderly individuals and test if novel eigen-PRSs derived from clustered subnetworks of single-trait PRSs can improve the prediction of LOAD diagnosis, rates of cognitive decline, and canonical LOAD neuropathology. Network analyses revealed distinct clusters of PRSs with clinical and biological interpretability. Novel eigen-PRSs (ePRS) from these clusters significantly improved LOAD-related phenotypes prediction over current state-of-the-art LOAD PRS models. Notably, an ePRS representing clusters of traits related to cholesterol levels was able to improve variance explained in a model of the brain-wide beta-amyloid burden by 1.7% (likelihood ratio test P = 9.02 × 10-7). All associations of ePRS with LOAD phenotypes were eliminated by the removal of APOE-proximal loci. However, our association analysis identified modules characterized by PRSs of high cholesterol and LOAD. We believe this is due to the influence of the APOE region from both PRSs. We found significantly higher mean SNP effects for LOAD in the intersecting APOE region SNPs. Combining genetic risk factors for vascular traits and dementia could improve current single-trait PRS models of LOAD, enhancing the use of PRS in risk stratification. Our results are catalogued for the scientific community, to aid in generating new hypotheses based on our maps of clustered PRSs and associations with LOAD-related phenotypes.

Escape from X-chromosome inactivation and sex differences in Alzheimer's disease

Sex differences exist in the onset and progression of Alzheimer's disease. Globally, women have a higher prevalence, while men with Alzheimer's disease experience earlier mortality and more pronounced cognitive decline than women. The cause of sex differences in Alzheimer's disease remains unclear. Accumulating evidence suggests the potential role of X-linked genetic factors in the sex difference of Alzheimer's disease (AD). During embryogenesis, a remarkable process known as X-chromosome inactivation (XCI) occurs in females, leading to one of the X chromosomes undergoing transcriptional inactivation, which balances the effects of two X chromosomes in females. Nevertheless, certain genes exceptionally escape from XCI, which provides a basis for dual expression dosage of specific genes in females. Based on recent research findings, we explore key escape genes and their potential therapeutic use associated with Alzheimer's disease. Also, we discuss their possible role in driving the sex differences in Alzheimer's disease. This will provide new perspectives for precision medicine and gender-specific treatment of AD.

The Cerebrospinal Fluid Free-Glycans Hex1 and HexNAc1Hex1Neu5Ac1 as Potential Biomarkers of Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder, affecting a growing number of elderly people. In order to improve the early and differential diagnosis of AD, better biomarkers are needed. Glycosylation is a protein post-translational modification that is modulated in the course of many diseases, including neurodegeneration. Aiming to improve AD diagnosis and differential diagnosis through glycan analytics methods, we report the glycoprotein glycome of cerebrospinal fluid (CSF) isolated from a total study cohort of 262 subjects. The study cohort consisted of patients with AD, healthy controls and patients suffering from other types of dementia. CSF free-glycans were also isolated and analyzed in this study, and the results reported for the first time the presence of 19 free glycans in this body fluid. The free-glycans consisted of complete or truncated N-/O-glycans as well as free monosaccharides. The free-glycans Hex1 and HexNAc1Hex1Neu5Ac1 were able to discriminate AD from controls and from patients suffering from other types of dementia. Regarding CSF N-glycosylation, high proportions of high-mannose, biantennary bisecting core-fucosylated N-glycans were found, whereby only about 20% of the N-glycans were sialylated. O-Glycans and free-glycan fragments were less sialylated in AD patients than in controls. To conclude, this comprehensive study revealed for the first time the biomarker potential of free glycans for the differential diagnosis of AD.

Oral Microbially-Induced Small Extracellular Vesicles Cross the Blood-Brain Barrier

Porphyromonas gingivalis (Pg) and its gingipain proteases contribute to Alzheimer's disease (AD) pathogenesis through yet unclear mechanisms. Cellular secretion of small extracellular vesicles or exosomes (EXO) increases with aging as part of the senescence-associated secretory phenotype (SASP). We have shown that EXO isolated from Pg-infected dendritic cells contain gingipains and other Pg antigens and transmit senescence to bystander gingival cells, inducing alveolar bone loss in mice in vivo. Here, EXO were isolated from the gingiva of mice and humans with/without periodontitis (PD) to determine their ability to penetrate the blood-brain barrier (BBB) in vitro and in vivo. PD was induced by Pg oral gavage for 6 weeks in C57B6 mice. EXO isolated from the gingiva or brain of donor Pg-infected (PD EXO) or control animals (Con EXO) were characterized by NTA, Western blot, and TEM. Gingival PD EXO or Con EXO were labeled and injected into the gingiva of uninfected WT mouse model. EXO biodistribution in brains was tracked by an in vivo imaging system (IVIS) and confocal microscopy. The effect of human PD EXO on BBB integrity and permeability was examined using TEER and FITC dextran assays in a human in vitro 3D model of the BBB. Pg antigens (RGP and Mfa-1) were detected in EXO derived from gingival and brain tissues of donor Pg-infected mice. Orally injected PD EXO from donor mice penetrated the brains of recipient uninfected mice and colocalized with hippocampal microglial cells. IL-1β and IL-6 were expressed in human PD EXO and not in Con EXO. Human PD EXO promoted BBB permeability and penetrated the BBB in vitro. This is the first demonstration that microbial-induced EXO in the oral cavity can disseminate, cross the BBB, and may contribute to AD pathogenesis.