Pages 431-445
Review
Masuo Ohno (Handling Associate Editor: Elliott Mufson)
A Strategy for Allowing Earlier Diagnosis and Rigorous Evaluation of BACE1 Inhibitors in Preclinical Alzheimer's Disease
Abstract: Given continued failure of BACE1 inhibitor programs at symptomatic and prodromal stages of Alzheimer’s disease (AD), clinical trials need to target the earlier preclinical stage. However, trial design is complex in this population with negative diagnosis of classical hippocampal amnesia on standard memory tests. Besides recent advances in brain imaging, electroencephalogram, and fluid-based biomarkers, new cognitive markers should be established for earlier diagnosis that can optimize recruitment to BACE1 inhibitor trials in presymptomatic AD. Notably, accelerated long-term forgetting (ALF) is emerging as a sensitive cognitive measure that can discriminate between asymptomatic individuals with high risks for developing AD and healthy controls. ALF is a form of declarative memory impairment characterized by increased forgetting rates over longer delays (days to months) despite normal storage within the standard delays of testing (20–60 min). Therefore, ALF may represent a harbinger of preclinical dementia and the impairment of systems memory consolidation, during which memory traces temporarily stored in the hippocampus become gradually integrated into cortical networks. This review provides an overview of the utility of ALF in a rational design of next-generation BACE1 inhibitor trials in preclinical AD. I explore potential mechanisms underlying ALF and relevant early-stage biomarkers useful for BACE1 inhibitor evaluation, including synaptic protein alterations, astrocytic dysregulation and neuron hyperactivity in the hippocampal-cortical network. Furthermore, given the physiological role of the isoform BACE2 as an AD-suppressor gene, I also discuss the possible association between the poor selectivity of BACE1 inhibitors and their side effects (e.g., cognitive worsening) in prior clinical trials.
Pages 447-470
Review
Zhen Huang (Handling Associate Editor: Ottavio Arancio)
Evidence that Alzheimer’s Disease Is a Disease of Competitive Synaptic Plasticity Gone Awry
Abstract: Mounting evidence indicates that a physiological function of amyloid-β (Aβ) is to mediate neural activity-dependent homeostatic and competitive synaptic plasticity in the brain. I have previously summarized the lines of evidence supporting this hypothesis and highlighted the similarities between Aβ and anti-microbial peptides in mediating cell/synapse competition. In cell competition, anti-microbial peptides deploy a multitude of mechanisms to ensure both self-protection and competitor elimination. Here I review recent studies showing that similar mechanisms are at play in Aβ-mediated synapse competition and perturbations in these mechanisms underpin Alzheimer’s disease (AD). Specifically, I discuss evidence that Aβ and ApoE, two crucial players in AD, co-operate in the regulation of synapse competition. Glial ApoE promotes self-protection by increasing the production of trophic monomeric Aβ and inhibiting its assembly into toxic oligomers. Conversely, Aβ oligomers, once assembled, promote the elimination of competitor synapses via direct toxic activity and amplification of “eat-me” signals promoting the elimination of weak synapses. I further summarize evidence that neuronal ApoE may be part of a gene regulatory network that normally promotes competitive plasticity, explaining the selective vulnerability of ApoE expressing neurons in AD brains. Lastly, I discuss evidence that sleep may be key to Aβ-orchestrated plasticity, in which sleep is not only induced by Aβ but is also required for Aβ-mediated plasticity, underlining the link between sleep and AD. Together, these results strongly argue that AD is a disease of competitive synaptic plasticity gone awry, a novel perspective that may promote AD research.
Pages 471-476
Short Communication
Eva Zupanic, Andreja Emersic, Anders Wimo, Bengt Winblad, Andreja Speh, Milica Gregoric Kramberger
Slovenian Memory Clinic Organization with the Introduction of Potential New Alzheimer’s Disease Treatment
Abstract: Slovenia, situated in Central Europe with a population of 2.1 million, has an estimated 44,278 individuals with mild cognitive impairment due to Alzheimer's disease or mild Alzheimer's dementia, rendering them potential candidates for disease-modifying treatment (DMT), such as lecanemab. We identified 114 potential candidates whose real-life expenses for diagnostic process surmount to more than €80,000. Treating all potential candidates nationwide would amount to €1.06 billion, surpassing Slovenia's entire annual medication expenditure for 2022 (€743 million). The introduction of DMTs and the associated logistics, along with potential complications, will significantly change societal, professional, and patient approach to treatment of Alzheimer's disease.
Pages 477-483
Short Communication
Morgan R. Miller, Lavender Lariviere, Guillaume J. Pagnier, Sema Aygar, Natalia Wieckiewic, Masato Maesako, Brian J. Bacskai, Ksenia V. Kastanenka
NB-02 Protects Neurons and Astrocytes from Oligomeric Amyloid-β-Mediated Damage
Abstract: Alzheimer’s disease (AD) is a progressive neurodegenerative disease with limited therapeutic strategies. NB-02 is a novel botanical drug that has shown promise as a protective and therapeutic treatment for AD in an APP/PS1 preclinical mouse model. In this paper, we investigate the underlying mechanisms by which NB-02 provides these therapeutic advantages using an in vitro neuron-astrocyte co-cultures. Pretreatment with NB-02 prevented pathological calcium elevations in neurons and astrocytes after application of toxic soluble amyloid-β (Aβ) oligomers. NB-02 also prevented cell death associated with the addition of soluble Aβ oligomers suggesting NB-02 is effective at protecting both neurons and astrocytes from Aβ-mediated damage.
Pages 485-488
Commentary
Fabricio Ferreira de Oliveira
Shedding Light on the Effects of Blood Pressure on Cognitive Decline and Dementia Risk by Way of Neurobiological Evidence
Abstract: Midlife cerebrovascular risk factors increase risk of late life cognitive impairment and dementia, while their presence in patients with dementia may lead to cognitive improvement or stabilization in late life. Defining the best measure of blood pressure (BP) to be associated with cognitive decline remains debatable, also due to possible bidirectionality. BP variability, pulse pressure, systolic and diastolic BP have been associated with cognitive status, dementia risk and Alzheimer’s disease biomarkers. Proper BP control notwithstanding, BP variability increases risk for pathophysiological change in the Alzheimer’s disease continuum, implying the need for selection of anti-hypertensive drugs with neurobiological evidence of benefits.
Pages 489-492
Commentary
Seth A. Gale
Language and Meaning: Asymptomatic Alzheimer’s Disease in the Clinic and Society
Abstract: As the biological, biomarker-driven framework of Alzheimer’s disease (AD) becomes formalized through revised, consensus clinical criteria, clinicians will confront more and more patients in the earliest, asymptomatic stages of disease. The language and diction used by practitioners to characterize these early patients, whether they are diagnosed with AD, and how their condition is documented in medical and legal records all have important implications for both their care and their medical-legal status outside of the health system. Investigation is needed urgently to better understand clinicians’ views and practices regarding early AD, as we adapt to new disease definitions in this unprecedented era of care.
Pages 493-501
Barak Gaster, Monica Zigman Suchsland, Annette L. Fitzpatrick, Joshua M. Liao, Basia Belza, Amy P. Hsu, Sarah McKiddy, Christina Park, Benjamin S. Olivari, Angad P. Singh, Jaqueline Raetz
Evaluating Cognitive Impairment in a Large Health Care System: The Cognition in Primary Care Program
Abstract: Background: The prevalence of Alzheimer’s disease and related disorders (ADRD) is rising. Primary care providers (PCPs) will increasingly be required to play a role in its detection but lack the training to do so. Objective: To develop a model for cognitive evaluation which is feasible in primary care and evaluate its implementation in a large health system. Methods: The Cognition in Primary Care Program consists of web-based training together with integrated tools built into the electronic record. We implemented the program among PCPs at 14 clinics in a large health system. We (1) surveyed PCPs to assess the impact of training on their confidence to evaluate cognition, (2) measured the number of cognitive assessments they performed, and (3) tracked the number of patients diagnosed with mild cognitive impairment (MCI). Results: Thirty-nine PCPs completed the training which covered how to evaluate cognition. Survey response rate from those PCPs was 74%. Six months after the end of the training, they reported confidence in assessing cognition (mean 4.6 on 5-point scale). Cognitive assessments documented in the health record increased from 0.8 per month before the training to 2.5 in the six months after the training. Patients who were newly diagnosed with MCI increased from 4.2 per month before the training to 6.0 per month in the six months after the training. Conclusions: This model for cognitive evaluation in a large health system was shown to increase cognitive testing and increase diagnoses of MCI. Such improvements are essential for the timely detection of ADRD.
Pages 503-511
Feifan Xu, Jiajie Xu, Qiong Wang, Feng Gao, Jiayu Fu, Tingmeng Yan, Qiang Dong, Ya Su, Xin Cheng
Serum YKL-40 as a Predictive Biomarker of Cerebral Amyloid Angiopathy-Related Intracerebral Hemorrhage Recurrence
Abstract: Background: Neuroinflammation is a major cause of secondary brain injury in intracerebral hemorrhage (ICH). To date, the prognostic value of YKL-40 (chitinase-3-like-1 protein), a biomarker of neuroinflammation, in cerebral amyloid angiopathy-related intracerebral hemorrhage (CAA-ICH) remains undiscovered. Objective: To evaluate the relationships between serum YKL-40 and CAA-ICH recurrence. Methods: Clinical and imaging information of 68 first-onset probable CAA-ICH cases and 95 controls were collected at baseline. Serum YKL-40 was measured by Luminex assay. Cox proportional hazards model was used to analyze the associations between YKL-40 level and CAA-ICH recurrence. Results: Serum YKL-40 level was significantly higher in CAA-ICH cases than healthy controls (median [interquartile range, IQR], 46.1 [19.8, 93.4] versus 24.4 [13.9, 59.0] ng/mL, p = 0.004). Higher level of YKL-40 predicted increased risk of CAA-ICH recurrence adjusted for age, ICH volume and enlarged perivascular space score (ePVS) (above versus below 115.5 ng/ml, adjusted hazard ratios 4.721, 95% confidence intervals 1.829–12.189, p = 0.001) within a median follow-up period of 2.4 years. Adding YKL-40 to a model of only MRI imaging markers including ICH volume and ePVS score improved the discriminatory power (concordance index from 0.707 to 0.772, p=0.001) and the reclassification power (net reclassification improvement 28.4%; integrated discrimination index 11.0%). Conclusions: Serum YKL-40 level might be a candidate prognostic biomarker for CAA-ICH recurrence.
Pages 513-523
Johanna A. Thunell, Geoffrey F. Joyce, Patricia M. Ferido, Yi Chen, Jenny S. Guadamuz, Dima M. Qato, Julie M. Zissimopoulos (Handling Associate Editor: Brian Downer)
Diagnoses and Treatment of Behavioral and Psychological Symptoms of Dementia Among Racially and Ethnically Diverse Persons Living with Dementia
Abstract: Background: Behavioral and psychological symptoms of dementia (BPSD) and prescribed central nervous system (CNS) active drugs to treat them are prevalent among persons living with Alzheimer’s disease and related dementias (PLWD) and lead to negative outcomes for PLWD and their caregivers. Yet, little is known about racial/ethnic disparities in diagnosis and use of drugs to treat BPSD. Objective: Quantify racial/ethnic disparities in BPSD diagnoses and CNS-active drug use among community-dwelling PLWD. Methods: We used a retrospective cohort of community-dwelling Medicare Fee-for-Service beneficiaries with dementia, continuously enrolled in Parts A, B and D, 2017-2019. Multivariate logistic models estimated rates of BPSD diagnosis and, conditional on diagnosis, CNS-active drug use. Results: Among PLWD, 67.1% had diagnoses of an affective, psychosis or hyperactivity symptom. White (68.3%) and Hispanic (63.9%) PLWD were most likely, Blacks (56.6%) and Asians (52.7%) least likely, to have diagnoses. Among PLWD with BPSD diagnoses, 78.6% took a CNS-active drug. Use was highest among whites (79.3%) and Hispanics (76.2%) and lowest among Blacks (70.8%) and Asians (69.3%). Racial/ethnic differences in affective disorders were pronounced, 56.8% of white PLWD diagnosed; Asians had the lowest rates (37.8%). Similar differences were found in use of antidepressants. Conclusions: BPSD diagnoses and CNS-active drug use were common in our study. Lower rates of BPSD diagnoses in non-white compared to white populations may indicate underdiagnosis in clinical settings of treatable conditions. Clinicians’ review of prescriptions in this population to reduce poor outcomes is important as is informing care partners on the risks/benefits of using CNS-active drugs.
Pages 525-533
Mengqing Liu, Nenghong Ma, Xiao Yang, Miao Sun, Xiaowen Li, Yuhui Liu, Qing Chang, Changchun Hei (Handling Associate Editor: Jian-Hong Wang)
The Association of Circulating Glucagon-Like Peptide-1 with Cognitive Functions and Biomarkers in Alzheimer's Disease
Abstract: Background: Alzheimer's disease (AD) is an age-related neurodegenerative disease that is clinically characterized by progressive cognitive decline. Glucagon-like peptide-1 (GLP-1) is a hormone that belongs to the incretin family and is released in response to nutrient intake. It plays a role in maintaining metabolic homeostasis and has been suggested to be involved in maintaining the brain microenvironment. However, the role of GLP-1 in AD pathogenesis has not been fully illustrated. Objective: This study aims to investigate the clinical relevance of GLP-1 in AD and the effects of GLP-1 in amyloid-β (Aβ) metabolism in vitro. Methods: In this study, 39 AD patients and 120 cognitively intact controls were included. Plasma levels of GLP-1 were measured using ELISA. SH-SY5Y cells overexpressing human amyloid precursor protein (APP) were treated with GLP-1. Western blot analysis was used to assess the effects of GLP-1 on the metabolism of Aβ. Results: Plasma GLP-1 levels were decreased with aging. Plasma GLP-1 levels were lower in AD patients in comparison with healthy older adults. Plasma GLP-1 levels were positively associated with Mini-Mental State Examination scores but negatively associated with plasma pTau181 levels. GLP-1 dose-dependently increased the area fraction of mitochondrial staining in vitro. Furthermore, GLP-1 dose-dependently promoted the α-cleavage of APP, thus reducing the generation of Aβ. Conclusions: GLP-1 has neuroprotective effects in AD, and therefore the decrease in GLP-1 levels during aging might contribute to the development of AD.
Pages 535-547
Irina Bulycheva, Yumi Watanabe, Kaori Kitamura, Keiko Kabasawa, Toshiko Saito, Akemi Takahashi, Ryosaku Kobayashi, Rieko Oshiki, Ribeka Takachi, Shoichiro Tsugane, Osamu Yamazaki, Kei Watanabe, Kazutoshi Nakamura
Self-Reported Sleep Duration and Bedtime Are Associated with Dementia Risk in Community-Dwelling People Aged 40–74 Years: The Murakami Cohort Study
Abstract: Background: Sleep is a potentially modifiable factor associated with dementia, including Alzheimer’s disease, but current evidence supporting this is insufficient. Objective: This study aimed to determine whether sleep duration and bedtime patterns are associated with the risk of dementia among middle-aged and older people. Methods: This cohort study had an eight-year follow-up period. Participants were 13,601 community-dwelling people aged 40–74 years living in Murakami (Niigata, Japan). Data were collected using a self-administered questionnaire. Predictors were self-reported sleep duration and bedtime, and the outcome was newly-diagnosed dementia determined using the long-term care insurance database. Covariates were demographic characteristics, body mass index, smoking, alcohol consumption, total physical activity, insomnia symptoms, disease history, and either bedtime or sleep duration. Cox proportional hazard models were used to calculate hazard ratios (HRs). Results: The mean age of participants at baseline was 59.2 years. Over a mean follow-up period of 8.0 years, 319 cases of dementia were observed. A long self-reported sleep duration relative to the reference sleep duration (7 hours) was associated with increased dementia risk, with the “8 hours” group (adjusted HR=1.30, 95%CI:0.99–1.73) and “≥9 hours” group (adjusted HR=1.46, 95%CI:1.00–2.15) having an increased risk (marginally significant) relative to the reference group. Early bedtime was associated with increased dementia risk (adjusted p for trend=0.0010), with the “21:00 or earlier” group (adjusted HR=1.61, 95%CI:1.14–2.28) having an increased risk relative to the reference (“23:00”). Conclusions: A long self-reported sleep duration and early bedtime are both associated with increased dementia risk in middle-aged and older people.
Pages 549-558
Takashi Asada, Mieko Tanaka, Wataru Araki, Adam Jon Lebowitz, Tatsuyuki Kakuma
Efficacy and Concurrent Validity of Computerized Brain Training Based on Everyday Living (BTEL) Based on Instrumental Activities of Living for Cognitively Healthy Old Individuals: A Preliminary Study
Abstract: Background: Interventions to prevent or attenuate cognitive decline and dementia in older adults are becoming increasingly important. Recently, cognitive training exercise can be via computer or mobile technology for independent or home use. Recent meta-analysis has reported that Computerized Cognitive Training (CCT) is effective at enhancing cognitive function in healthy older and Alzheimer’s disease adults, although little is known about individual characteristics of each computerized program. Objective: We developed a new CCT named Brain Training Based on Everyday Living (BTEL) to enhance cognitive capacity for Instrumental Activities of Daily Living (IADL). We aim to evaluate the efficacy of the BTEL among cognitively healthy old individuals and to explore its concurrent validity and construct concept. Methods: We conducted a double-blind study where 106 individuals aged 65 years and older (intervened=53, control=53) worked on the active and placebo tasks three times a week over three months (clinical trial: UMIN000048730). The main results were examined using ANCOVA and calculating correlation coefficients. Results: We found no effect on total score of the three tests; however, there was significant effect for the BTEL on: recognition in MMSE, and immediate recall in HDSR. The tasks are associated with prefrontal cortex. In addition, correlations indicated that each BTEL domain had some validity as a cognitive assessment tool. Different from previous CCT, we determined the neuropsychological characteristics of specific cognitive tasks of the BTEL to a certain degree. Conclusions: We found modest efficacy of the BTEL in cognitively healthy old individuals and confirmed its concurrent validity and the conceptual construct.
Pages 559-575
Annelie Scharf*, Fabian Kleinke*, Bernhard Michalowsky, Anika Rädke, Stefanie Pfitzner, Franka Mühlichen, Maresa Buchholz, Neeltje van den Berg, Wolfgang Hoffmann *These authors contributed equally to this work.
Sociodemographic and Clinical Characteristics of People Living with Dementia and Their Associations with Unmet Healthcare Needs: Insights from the Baseline Assessment of the InDePendent Study
Abstract: Background: The healthcare needs of People living with Dementia (PlwD) (such as Alzheimer's disease) are often unmet. Information about the needs of community-dwelling PlwD and their association with sociodemographic and clinical characteristics is needed to fill the knowledge gap regarding factors influencing unmet needs among PlwD and to conduct a comprehensive needs assessment to develop tailored interventions. Objective: To describe sociodemographic and clinical characteristics of the InDePendent study population with particular reference to determinants of unmet needs. Methods: We analyzed baseline data of the multi-centre cluster-randomized controlled trial (InDePendent) using descriptive statistics to describe patients' sociodemographic and clinical characteristics and Poisson regression models to predict unmet needs, separated by sex. Data were collected personally via face-to-face interviews. Results: Most of the n=417 participating PlwD were mild to moderately cognitively impaired, were not depressed, had an average of 10.8 diagnoses, took 6.7 medications, and had, on average, 2.4 unmet needs (62% of PlwD had at least one unmet need) measured by the Camberwell Assessment of Need for the Elderly (CANE). Low social support, a high body-mass index, a lower education, functional impairment, and worse health status were associated with more unmet needs, regardless of sex. In women, higher unmet needs were associated with more depressive symptoms, a poor financial situation, living alone and not being recently treated by a general practitioner. In males, unmet needs increased with the number of medications taken Conclusions: PlwD had a broad array of unmet healthcare needs, indicating primary healthcare provision improvement potentials. The results underscore the significance of early assessment of patient's clinical characteristics and unmet needs as a basis for individualized gender-sensible intervention strategies.
Pages 577-593
Yaoru Li*, Ziying Yang*, Yanxin Zhang, Fang Liu, Jing Xu, Yaping Meng, Gebeili Xing, Xuqin Ruan, Jun Sun, Nan Zhang (Handling Associate Editor: Jia Liu) *These authors contributed equally to this work.
Genetic Screening of Patients with Sporadic Alzheimer’s Disease and Frontotemporal Lobar Degeneration in the Chinese Population
Abstract: Background: Alzheimer’s disease (AD) and frontotemporal lobar degeneration (FTLD) account for the vast majority of neurodegenerative dementias. AD and FTLD have different clinical phenotypes with a genetic overlap between them and other dementias. Objective: This study aimed to identify the genetic spectrum of sporadic AD and FTLD in the Chinese population. Methods: A total of 74 sporadic AD and 29 sporadic FTLD participants were recruited. All participants underwent whole-exome sequencing (WES) and testing for a hexanucleotide expansion in C9orf72 was additionally performed for participants with negative WES results. Results: Four known pathogenic or likely pathogenic variants, including PSEN1 (p.G206D), MAPT (p.R5H), LRRK2 (p.Trp1434*), and CFAP43 (p.C934*), were identified in AD participants, and 1 novel pathogenic variant of ANXA11 (p.D40G) and two known likely pathogenic variants of MAPT (p.D177V) and TARDBP (p.I383V) were identified in FTLD participants. Twenty-four variants of uncertain significance as well as rare variants in risk genes for dementia, such as ABCA7, SORL1, TRPM7, NOS3, MPO, and DCTN1, were also found. Interestingly, several variants in participants with semantic variant primary progressive aphasia were detected. However, no participants with C9orf72 gene variants were found in the FTLD cohort. Conclusions: There was a high frequency of genetic variants in Chinese participants with sporadic AD and FTLD and a complex genetic overlap between these two types of dementia and other neurodegenerative diseases.
Pages 595-607
Carlos Antonio García-Carlos, Gustavo Basurto-Islas, George Perry, Siddhartha Mondragón-Rodríguez (Handling Editor: Jesus Avila)
Meta-Analysis in Transgenic Alzheimer’s Disease Mouse Models Reveals Opposite Brain Network Effects of Amyloid-β and Phosphorylated Tau Proteins
Abstract: Background: Cognitive deficits observed in Alzheimer’s disease (AD) patients have been correlated with altered hippocampal activity. Although the mechanism remains under extensive study, neurofibrillary tangles and amyloid plaques have been proposed as responsible for brain activity alterations. Aiming to unveil the mechanism, researchers have developed several transgenic models of AD. Nevertheless, the variability in hippocampal oscillatory alterations found in different genetic backgrounds and ages remains unclear. Objective: To assess the oscillatory alterations in relation to animal developmental age and protein inclusion, amyloid-β (Aβ) load, and abnormally phosphorylated tau (pTau), we reviewed and analyzed the published data on peak power, frequency, and quantification of theta-gamma cross-frequency coupling (modulation index values). Methods: To ensure that the search was as current as possible, a systematic review was conducted to locate and abstract all studies published from January 2000 to February 2023 that involved in vivo hippocampal local field potential recording in transgenic mouse models of AD. Results: The presence of Aβ was associated with electrophysiological alterations that are mainly reflected in power increases, frequency decreases, and lower modulation index values. Concomitantly, pTau accumulation was associated with electrophysiological alterations that are mainly reflected in power decreases, frequency decreases, and no significant alterations in modulation index values. Conclusions: In this study, we showed that electrophysiological parameters are altered from prodromal stages to the late stages of pathology. Thus, we found that Aβ deposition is associated with brain network hyperexcitability, whereas pTau deposition mainly leads to brain network hypoexcitability in transgenic models.
Pages 609-622
Alexandra Horvath, Patrick Quinlan, Carl Eckerström, N. David Åberg, Anders Wallin, Johan Svensson (Handling Associate Editor: Natalia García-Casares)
The Associations Between Serum Insulin-like Growth Factor-I, Brain White Matter Volumes, and Cognition in Mild Cognitive Impairment and Alzheimer’s Disease
Abstract: Background: Insulin-like growth factor-I (IGF-I) regulates myelin, but little is known whether IGF-I associates with white matter functions in subjective and objective mild cognitive impairment (SCI/MCI) or Alzheimer’s disease (AD). Objective: To explore whether serum IGF-I is associated with magnetic resonance imaging - estimated brain white matter volumes or cognitive functions. Methods: In a prospective study of SCI/MCI (n = 106) and AD (n = 59), we evaluated the volumes of the total white matter, corpus callosum (CC), and white matter hyperintensities (WMHs) as well as Mini-Mental State Examination (MMSE), Trail Making Test A and B (TMT-A/B), and Stroop tests I-III at baseline, and after 2 years. Results: IGF-I was comparable in SCI/MCI and AD (113 versus 118 ng/mL, p = 0.44). In SCI/MCI patients, the correlations between higher baseline IGF-I and greater baseline and 2-year volumes of the total white matter and total CC lost statistical significance after adjustment for intracranial volume and other covariates. However, after adjustment for covariates, higher baseline IGF-I correlated with better baseline scores of MMSE and Stroop test II in SCI/MCI and with better baseline results of TMT-B and Stroop test I in AD. IGF-I did not correlate with WMH volumes or changes in any of the variables. Conclusions: Both in SCI/MCI and AD, higher IGF-I was associated with better attention/executive functions at baseline after adjustment for covariates. Furthermore, the baseline associations between IGF-I and neuropsychological test results in AD may argue against significant IGF-I resistance in the AD brain.
Pages 623-637
Ashar Memon, Jasmine A. Moore, Chris Kang, Zahinoor Ismail, Nils D. Forkert for the Alzheimer’s Disease Neuroimaging Initiative
Visual Functions Are Associated with Biomarker Changes in Alzheimer’s Disease
Abstract: Background: While various biomarkers of Alzheimer’s disease (AD) have been associated with general cognitive function, their association to visual-perceptive function across the AD spectrum warrant more attention due to its significant impact on quality of life. Thus, this study explores how AD biomarkers are associated with decline in this cognitive domain. Objective: To explore associations between various fluid and imaging biomarkers and visual-based cognitive assessments in participants across the AD spectrum. Methods: Data from participants (N = 1,460) in the Alzheimer's Disease Neuroimaging Initiative were analyzed, including fluid and imaging biomarkers. Along with the Mini-Mental State Examination (MMSE), three specific visual-based cognitive tests were investigated: Trail Making Test (TMT) A and TMT B, and the Boston Naming Test (BNT). Locally estimated scatterplot smoothing curves and Pearson correlation coefficients were used to examine associations. Results: MMSE showed the strongest correlations with most biomarkers, followed by TMT-B. The p-tau181/Aβ1-42 ratio, along with the volume of the hippocampus and entorhinal cortex, had the strongest associations among the biomarkers. Conclusions: Several biomarkers are associated with visual processing across the disease spectrum, emphasizing their potential in assessing disease severity and contributing to progression models of visual function and cognition.
Pages 639-656
Daniela Giraldo-Berrio, Marlene Jimenez-Del-Rio, Carlos Velez-Pardo
Sildenafil Reverses the Neuropathological Alzheimer’s Disease Phenotype in Cholinergic-Like Neurons Carrying the Presenilin 1 E280A Mutation
Abstract: Background: Familial Alzheimer’s disease (FAD) presenilin 1 E280A (PSEN 1 E280A) is characterized by functional impairment and the death of cholinergic neurons as a consequence of amyloid-β (Aβ) accumulation and abnormal phosphorylation of the tau protein. Currently, there are no available therapies that can cure FAD. Therefore, new therapies are urgently needed for treating this disease. Objective: To assess the effect of sildenafil (SIL) on cholinergic-like neurons (ChLNs) harboring the PSEN 1 E280A mutation. Methods: Wild-type (WT) and PSEN 1 E280A ChLNs were cultured in the presence of SIL (25 µM) for 24 h. Afterward, proteinopathy, cell signaling, and apoptosis markers were evaluated via flow cytometry and fluorescence microscopy. Results: We found that SIL was innocuous toward WT PSEN 1 ChLNs but reduced the accumulation of intracellular Aβ fragments by 87%, decreased the non-physiological phosphorylation of the protein tau at residue Ser202/Thr205 by 35%, reduced the phosphorylation of the proapoptotic transcription factor c-JUN at residue Ser63/Ser73 by 63%, decreased oxidized DJ-1 at Cys106-SO3 by 32%, and downregulated transcription factor TP53 (tumor protein p53), BH-3-only protein PUMA (p53 upregulated modulator of apoptosis), and cleaved caspase 3 (CC3) expression by 20%, 32%, and 22%, respectively, compared with untreated mutant ChLNs. Interestingly, SIL also ameliorated the dysregulation of acetylcholine-induced calcium ion (Ca2+) influx in PSEN 1 E280A ChLNs. Conclusions: Although SIL showed no antioxidant capacity in the oxygen radical absorbance capacity and ferric ion reducing antioxidant power assays, it might function as an anti-amyloid and antiapoptotic agent and functional neuronal enhancer in PSEN 1 E280A ChLNs. Therefore, the SIL has therapeutic potential for treating FAD.
Pages 657-665
Jiaqi Liu*, Sirui Sun*, Yongjie Chen *These authors contributed equally to this work.
Superoxide Dismutase Modified the Association of Serum Malondialdehyde Levels with Cognitive Decline Among Older Adults: Findings from the Chinese Longitudinal Healthy Longevity Survey
Abstract: Background: Numerous studies have investigated the correlation between malondialdehyde (MDA) and cognitive decline. However, limited research has explored the interplay between superoxide dismutase (SOD), C-reactive protein (CRP), and MDA. Objective: This study aims to scrutinize the association between MDA and cognitive function in older adults, while also elucidating the roles of SOD and CRP within this relationship. Methods: Utilizing data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) spanning 2008-2009, 2011-2012, and 2014, this study included 2,696 eligible subjects. Cognitive function was evaluated using the Chinese version of the Mini-Mental State Examination (MMSE). Linear mixed-effects models were employed to examine the links between MDA, SOD, CRP, and their interactions with cognitive function. Results: Elevated serum levels of MDA and CRP, as well as decreased serum SOD levels, were related to decreased cognitive function (β=-0.220 and -0.346, 95% CI: -0.399, -0.041 and -0.526, -0.167 for MDA and CRP; β=0.384, 95% CI: 0.204, 0.564 for SOD). Notably, a significant interaction between MDA and SOD was detected (p=0.001). An increase per standard deviation in serum MDA levels was significantly associated with a 0.347-point lower MMSE score only in participants with normal cognitive function and high SOD levels (β=-0.347, 95% CI: -0.497, -0.197; p<0.001). Conclusions: Elevated serum MDA levels in the normal population with high SOD levels suggested diminished cognitive performance. Combining MDA with SOD could be pivotal in identifying older adults at risk of cognitive decline in clinical settings.
Pages 667-678
Yili Chu, Qihui Xie, Rongrong Meng, Bin Len, Zhenxiang Cao
Evaluation of the Quality and Readability of Online Information about Alzheimer's Disease in China
Abstract: Background: With the increasing popularity of the internet, a growing number of patients and their companions are actively seeking health-related information online. Objective: The aim of this study was to assess the quality and readability of online information about Alzheimer's disease (AD) in China. Methods: A total of 263 qualified AD-related web pages from different businesses, governments, and hospitals were obtained. The quality of the web pages was assessed using the DISCERN tool, and the readability of the web pages was assessed using a readability measurement website suitable for the Chinese language. The differences in readability and quality between different types of web pages were investigated, and the correlation between quality and readability was analyzed. Results: The mean overall DISCERN score was 40.93±7.5. The government group scored significantly higher than the commercial and hospital groups. The mean readability score was 12.74±1.27, and the commercial group had the lowest readability score. There was a positive correlation between DISCERN scores and readability scores. Conclusions: This study presents an evaluation of the quality and readability of health information pertaining to AD in China. The findings indicate that there is a need to enhance the quality and readability of web pages about AD in China. Recommendations for improvement are proposed in light of these findings.
Pages 679-691
Tugce Duran, Sarah A. Gaussoin, Lauren A. Latham, Melissa M. Rundle, Mark A. Espeland, Benjamin J. Williams, Timothy M. Hughes, Suzanne Craft, Bonnie C. Sachs, James R. Bateman, Samuel N. Lockhart
Examining a Preclinical Alzheimer’s Cognitive Composite for Telehealth Administration for Reliability Between In-Person and Remote Cognitive Testing with Neuroimaging Biomarkers
Abstract: Background: The preclinical Alzheimer’s cognitive composite (PACC) was developed for in-person administration to capture subtle cognitive decline. At the outset of the COVID-19 pandemic, cognitive testing was increasingly performed remotely by telephone or video administration. It is desirable to have a harmonized composite measurement derived from both in-person and remote assessments for identifying cognitive changes and to examine its relationship with common neuroimaging biomarkers. Objective: We defined a telehealth compatible PACC (tPACC) and examined its relationship with neuroimaging biomarkers related to neurodegeneration, brain function and perfusion, white matter integrity, and amyloid-β. Methods: We examined 648 participants’ neuroimaging and in-person and remote cognitive testing data from the Wake Forest Alzheimer’s Disease Research Center’s Clinical Core cohort (observational study) to calculate a modified PACC (PACC5-RAVLT) score and tPACC scores (in-person and remote). We performed Spearman/intraclass correlation coefficient (ICC) analyses for reliability of tPACC scores and linear regression models to evaluate associations between tPACC and neuroimaging. Bland-Altman plots for agreement were constructed across cognitively normal and impaired (mild cognitive impairment and dementia) participants. Results: There was a significant positive relationship between tPACCin-person and PACC5-RAVLT (Overall group: r2=0.94, N=648), and tPACCin-person and tPACCremote (validation subgroup: ICC=0.82, n=53). Overall, tPACC showed significant associations with brain thickness/volume, gray matter perfusion, white matter free water, and amyloid-β deposition. Conclusions: There is a good agreement between tPACC and PACC5-RAVLT for cognitively normal and impaired individuals. The tPACC is associated with common neuroimaging markers of Alzheimer’s disease.
Pages 693-703
Yomna Elghanam, Sujata Purja, Eun Young Kim (Handling Associate Editor: Inês Baldeiras)
Biomarkers as Endpoints in Clinical Trials for Alzheimer’s Disease
Abstract: Background: Alzheimer's disease (AD) is a neurodegenerative disease that imposes economic and societal burden. Biomarkers have played a crucial role in the recent approval of aducanumab and lecanemab as disease-modifying therapies which marked a significant milestone for the treatment of AD. The inclusion of biomarkers in AD trials facilitates precise diagnosis, monitors safety, demonstrates target engagement, and supports disease modification. Objective: This study analyzed the utilization state and trends of biomarkers as endpoints in AD trials. Methods: In this retrospective study, trials were collected by searching clinicaltrials.gov using the term “Alzheimer”. Primary and secondary outcomes were analyzed separately for each phase. Results: Among the 1,048 analyzed trials, 313 (29.87%) adopted biomarkers as primary endpoints and 364 (34.73%) as secondary endpoints, mainly in phases 1 and 2. The top three biomarkers adopted as primary endpoints in phases 1, 2, and 3 were amyloid-PET, tau-PET, and MRI. The top three biomarkers adopted as secondary endpoints, in phase 1, were cerebrospinal fluid (CSF) amyloid-β (Aβ), blood Aβ and amyloid-PET; in phase 2, they were MRI, CSF Aβ, and CSF phospho-tau; and in phase 3, they were amyloid PET, MRI, and blood Aβ. There was a statistically significant increase in the adoption of biomarkers as primary endpoints in phase 2 trials (p=0.001) and secondary endpoints in phase 3 trials (p=0.001). Conclusions: The growing recognition of the importance of biomarkers in AD trial’ design and drug development is evident by the significant steady increase in biomarkers’ utilization in phases 2 and 3.
Pages 705-714
Yoo Hyun Um, Sheng-Min Wang, Dong Woo Kang, Sunghwan Kim, Chang Uk Lee, Donghyeon Kim, Yeong Sim Choe, Regina E.Y. Kim, Soyoung Lee, Min-Kyung Lee, Hyun Kook Lim
Impact of Apolipoprotein E4 on the Locus Coeruleus Functional Connectivity in Preclinical Alzheimer's Disease
Abstract: Background: Recent interest has surged in the locus coeruleus (LC) for its early involvement in Alzheimer's disease (AD), notably concerning the apolipoprotein ε4 allele (APOE4). Objective: This study aimed to discern LC functional connectivity (FC) variations in preclinical AD subjects, dissecting the roles of APOE4 carrier status and amyloid-β (Aβ) deposition. Methods: A cohort of 112 cognitively intact individuals, all Aβ-positive, split into 70 APOE4 noncarriers and 42 carriers, underwent functional MRI scans, neuropsychological assessments, and APOE genotyping. The research utilized seed to voxel analysis for illustrating LC rsFC discrepancies between APOE4 statuses and employed a general linear model to examine the interactive influence of APOE4 carrier status and Aβ deposition on LC FC values. Results: The investigation revealed no significant differences in sex, age, or SUVR between APOE4 carriers and noncarriers. It found diminished LC FC with the occipital cortex in APOE4 carriers and identified a significant interaction between APOE4 carrier status and temporal lobe SUVR in LC FC with the occipital cortex. This interaction suggested a proportional increase in LC FC for APOE4 carriers. Additional notable interactions were observed affecting LC FC with various brain regions, indicating a proportional decrease in LC FC for APOE4 carriers. Conclusions: These findings confirm that APOE4 carrier status significantly influences LC FC in preclinical AD, showcasing an intricate relationship with regional Aβ deposition. This underscores the critical role of genetic and pathological factors in early AD pathophysiology, offering insights into potential biomarkers for early detection and intervention strategies.
Pages 715-727
Linhui Xie*, Yash Raj*, Pradeep Varathan, Bing He, Meichen Yu, Kwangsik Nho, Paul Salama, Andrew J. Saykin, Jingwen Yan *These authors contributed equally to this work.
Deep Trans-Omic Network Fusion for Molecular Mechanism of Alzheimer’s Disease
Abstract: Background: There are various molecular hypotheses regarding Alzheimer's disease (AD) like amyloid deposition, tau propagation, neuroinflammation, and synaptic dysfunction. However, detailed molecular mechanism underlying AD remains elusive. In addition, genetic contribution of these molecular hypothesis is not yet established despite the high heritability of AD. Objective: The study aims to enable the discovery of functionally connected multi-omic features through novel integration of multi-omic data and prior functional interactions. Methods: We propose a new deep learning model MoFNet with improved interpretability to investigate the AD molecular mechanism and its upstream genetic contributors. MoFNet integrates multi-omic data with prior functional interactions between SNPs, genes, and proteins, and for the first time models the dynamic information flow from DNA to RNA and proteins. Results: When evaluated using the ROS/MAP cohort, MoFNet outperformed other competing methods in prediction performance. It identified SNPs, genes, and proteins with significantly more prior functional interactions, resulting in three multi-omic subnetworks. SNP-gene pairs identified by MoFNet were mostly eQTLs specific to frontal cortex tissue where gene/protein data was collected. These molecular subnetworks are enriched in innate immune system, clearance of misfolded proteins, and neurotransmitter release respectively. We validated most findings in an independent dataset. One multi-omic subnetwork consists exclusively of core members of SNARE complex, a key mediator of synaptic vesicle fusion and neurotransmitter transportation. Conclusions: Our results suggest that MoFNet is effective in improving classification accuracy and in identifying multi-omic markers for AD with improved interpretability. Multi-omic subnetworks identified by MoFNet provided insights of AD molecular mechanism with improved details.
Pages 729-737
Sylwia Libard, Monika Hodik, Kristina Giuliana Cesarini, Anca Dragomir, Irina Alafuzoff
The Compartmentalization of Amyloid-β in Idiopathic Normal Pressure Hydrocephalus Brain Biopsies
Abstract: Background: Amyloid-β (Aβ) is one of the hallmark lesions of Alzheimer’s disease (AD). During the disease process, Aβ undergoes biochemical changes, producing toxic Aβ variants, proposed to be detected within the neurons. Idiopathic normal pressure hydrocephalus (iNPH) causes cognitive impairment, gait, and urinary symptoms in elderly, that can be reversed by a ventriculo-peritoneal shunt. Majority of iNPH subjects display different Aβ variants in their brain biopsies, obtained during shunting. Objective: To study the cellular compartmentalization of different Aβ variants in brain biopsies from iNPH subjects. Methods: We studied the cellular localization of different proteoforms of Aβ using antibodies towards different amino acid sequences or post-translational modifications of Aβ, including clones 4G8, 6F/3D, unmodified- (7H3D6), pyroglutamylated- (N3pE), phosphorylated-(1E4E11) Aβ and Aβ protein precursor (AβPP), in brain biopsies from 3 iNPH subjects, using immunohistochemistry and light microscopy (LM), light microscopy on semi-thin sections (LMst), and electron microscopy (EM). Results: In LM all Aβ variants were detected. In LMst and EM, the Aβ 4G8, 6F/3D, and the pyroglutamylated Aβ were detected. The AβPP was visualized by all methods. The Aβ labelling was located extracellularly with no specific signal within the intracellular compartment, whereas the AβPP was seen both intra- and extracellularly. Conclusions: The Aβ markers displayed extracellular localization when visualized by three assessment techniques, reflecting the pathological extracellular accumulation of Aβ in the human brain. No intracellular Aβ pathology was seen. AβPP was visualized in intra- and extracellularly, which corresponds to the localization of the protein in the membranes of cells and organelles.
Pages 739-752
Jing Xu*, Yao Chen*, Yi Shi, Anna Sun, Yuedi Yang, Malaz Boustani, Jing Su, Pengyue Zhang *These authors contributed equally to this work.
Associations Between Neuroinflammation-Related Conditions and Alzheimer’s Disease: A Study of US Insurance Claims Data
Abstract: Background: Early detection of Alzheimer's disease (AD) is a key component for the success of the recently approved lecanemab and aducanumab. Patients with neuroinflammation-related conditions are associated with a higher risk for developing AD. Objective: Investigate the incidence of AD among patients with neuroinflammation-related conditions including epilepsy, hemorrhage stroke, multiple sclerosis (MS), and traumatic brain injury (TBI). Methods: We used Optum’s de-identified Clinformatics Data Mart Database (CDM). We derived covariate-matched cohorts including patients with neuroinflammation-related conditions and controls without the corresponding condition. The matched cohorts were: 1) patients with epilepsy and controls (N=67,825 matched pairs); 2) patients with hemorrhage stroke and controls (N=81,510 matched pairs); 3) patients with MS and controls (N=9,853 matched pairs); and 4) patients TBI and controls (N=104,637 matched pairs). We used the Cox model to investigate the associations between neuroinflammation-related conditions and AD. Results: We identified that epilepsy, hemorrhage stroke, and TBI were associated with increased risks of AD in both males and females (hazard ratios [HRs]≥1.74, p<0.001), as well as in gender- and race-conscious subpopulations (HRs≥1.64, p<0.001). We identified that MS was associated with increased risks of AD in both males and females (HRs≥1.47, p≤0.004), while gender- and race-conscious subgroup analysis shown mixed associations. Conclusions: Patients with epilepsy, hemorrhage stroke, MS, and/or TBI are associated with a higher risk of developing AD. More attention on cognitive status should be given to older patients with these conditions.
Pages 753-772
Michael F. Georgescu*, May A. Beydoun*, Jason Ashe, Christian A. Maino Vieytes, Hind A. Beydoun, Michele K. Evans, Alan B. Zonderman *These authors contributed equally to this work.
Loneliness, Dementia Status, and Their Association with All-Cause Mortality Among Older US Adults
Abstract: Background: Loneliness, dementia, and mortality are interconnected. Objective: We aimed at understanding mediating pathways and interactions between loneliness and dementia in relation to mortality risk. Methods: The study tested bi-directional relationships between dementia, loneliness, and mortality, by examining both interactions and mediating effects in a large sample of older US adults participating in the nationally representative Health and Retirement Study. Out of ≤6,468 older participants selected in 2010, with mean baseline age of 78.3 years and a follow-up time up to the end of 2020, 3,298 died at a rate of 64 per 1,000 person-years (P-Y). Cox proportional hazards and four-way decomposition models were used. Results: Algorithmically defined dementia status (yes versus no) was consistently linked with a more than two-fold increase in mortality risk. Dementia status and Ln(odds of dementia) were strongly related with mortality risk across tertiles of loneliness score. Loneliness z-score was also linked to an elevated risk of all-cause mortality regardless of age, sex, or race or ethnicity, and that its total effect (TE) on mortality was partially mediated by Ln(odds of dementia), z-scored, (≤40% of the TE was a pure indirect effect). Conversely, a small proportion (<5%) of the TE of Ln (odds of dementia), z-scored, on mortality risk was explained by the loneliness z-score. Conclusions: In sum, dementia was positively associated with all-cause mortality risk, in similar fashion across loneliness score tertiles, while loneliness was associated with mortality risk. TE of loneliness on mortality risk was partially mediated by dementia odds in reduced models.
Pages 773-785
Bin Wu, Mulan Chen, Ling Meng, Qiuyun Tian, Zhifang Dong (Handling Associate Editor: Ling-Qiang Zhu)
Osteoclasts Link Dysregulated Peripheral Degradation Processes and Accelerated Progression in Alzheimer’s Disease
Abstract: Background: The amyloid-β (Aβ) enhances the number and activity of blood monocyte-derived osteoclasts (OCs). Individuals with osteoporosis (OP) face an increased risk of developing dementia or Alzheimer's disease (AD). Despite this association, the contribution of bone-resorbing OCs to the progression of AD pathology remains unclear. Objective: Our objective was to investigate the potential impacts of OCs on the development of AD pathology. Methods: We conducted targeted analysis of publicly available whole blood transcriptomes from patients with AD to characterize the blood molecular signatures and pathways associated with hyperactive OCs. In addition, we used APP23 transgenic (APP23 TG) AD mouse model to assess the effects of OCs pharmacological blockade on AD pathology and behavior. Results: Patients with AD exhibited increased osteoclastogenesis signature in their blood cells, which appears to be positively correlated with dysfunction of peripheral clearance of Aβ mediated by immune cells. Long-term anti-resorptive intervention with Alendronate inhibited OC activity in APP23 mice, leading to improvements in peripheral monocyte Aβ-degrading enzyme expression, Aβ-deposition, and memory decline. Conclusions: Our findings suggest that OCs have a disease-promoting role in the development and progression of AD, possibly linked to their modulation of peripheral immunity. These findings guide future research to further elucidate the connection between OP and AD pathogenesis, highlighting the potential benefits of preventing OP in alleviating cognitive burden.
Pages 787-797
Xiaqing Jiang, Amber L. Bahorik, Neill R. Graff-Radford, Kristine Yaffe
Association of Plasma Amyloid-β and Dementia Among Black and White Older Adults
Abstract: Background: Plasma amyloid-β (Aβ) has emerged as an important tool to detect risks of Alzheimer’s disease and related dementias, although research in diverse populations is lacking. Objective: We compared plasma Aβ42/40 by race with dementia risk over 15 years among Black and White older adults. Methods: In a prospective cohort of 997 dementia-free participants (mean age 74 ± 2.9 years, 55% women, 54% Black), incident dementia was identified based on hospital records, medication, and neurocognitive test over 15 years. Plasma Aβ42/40 was measured at Year 2 and categorized into low, medium, and high tertile. We used linear regression to estimate mean Aβ42/40 by race and race-stratified Cox proportional hazards models to assess the association between Aβ42/40 tertile and dementia risk. Results: Black participants had lower age-adjusted mean Aβ42/40 compared to White participants, primarily among APOE ε4 non-carriers (Black: 0.176, White: 0.185, p=0.035). Among Black participants, lower Aβ42/40 was associated with increased dementia risk: 33% in low (hazard ratios [HR]=1.77, 95% confidence interval 1.09-2.88) and 27% in medium tertile (HR=1.67, 1.01-2.78) compared with 18% in high Aβ42/40 tertile; Increased risks were attenuated among White participants: 21% in low (HR=1.43, 0.81-2.53) and 23% in medium tertile (HR=1.27, 0.68-2.36) compared with 15% in high Aβ 42/40 tertile. The interaction by race was not statistically significant. Conclusions: Among community-dwelling, non-demented older adults, especially APOE ε4 non-carriers, Black individuals had lower plasma Aβ42/40 and demonstrated a higher dementia risk with low Aβ42/40 compared with White individuals.
