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Background: Tau‐first cognitive proteinopathy (TCP) denotes a clinical phenotype of Alzheimer disease (AD) showing Florzolotau(18F) positron emission tomography (PET) positivity but a negative amyloid status. Aim: We explored the biological property of tau using longitudinal cognitive and neuroimaging data in TCP and compared with late‐onset AD (LOAD). Method: We enrolled 56 patients with LOAD, 34 patients with TCP, and 26 cognitive unimpaired controls. All of the participants had historical data of 2 to 4 three‐dimensional T1 images and 2 to 6 annual cognitive evaluations over a follow‐up period of 7 years. Tau topography was measured using Florzolotau(18F) PET. In the LOAD and TCP groups, we constructed tau or gray matter clusters covarying with the cognitive measurements. We used mediator analysis to explore the regional tau load as predictor, gray matter partitions as mediators, and significant cognitive test scores as outcomes. Longitudinal cognitive decline and cortical thickness degeneration pattern were analyzed using a linear mixed‐effects model. Results: The TCP group had longitudinal declines in nonexecutive domains. The deterministic factor predicting the short‐term memory score in TCP was the hippocampal volume and not directly via the medial and lateral temporal tau load. These features formed the conceptual differences with LOAD. Discussion: The biological properties of tau and the longitudinal cognitive‐imaging trajectory support the conceptual distinction between TCP and LOAD. TCP represents one specific entity featuring salient short‐term memory impairment, declines in nonexecutive domains, a slower gray matter degenerative pattern, and a restricted impact of tau. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Although glymphatic function is involved in Alzheimer's disease (AD), its potential for predicting the pathological and clinical progression of AD and its sequential association with core AD biomarkers is poorly understood. METHODS: Whole‐brain glymphatic activity was measured by diffusion tensor image analysis along the perivascular space (DTI‐ALPS) in participants with AD dementia (n = 47), mild cognitive impairment (MCI; n = 137), and normal controls (n = 235) from the Alzheimer's Disease Neuroimaging Initiative. RESULTS: ALPS index was significantly lower in AD dementia than in MCI or controls. Lower ALPS index was significantly associated with faster changes in amyloid positron emission tomography (PET) burden and AD signature region of interest volume, higher risk of amyloid‐positive transition and clinical progression, and faster rates of amyloid‐ and neurodegeneration‐related cognitive decline. Furthermore, the associations of the ALPS index with cognitive decline were fully mediated by amyloid PET and brain atrophy. DISCUSSION: Glymphatic failure may precede amyloid pathology, and predicts amyloid deposition, neurodegeneration, and clinical progression in AD. Highlights: The analysis along the perivascular space (ALPS) index is reduced in patients with Alzheimer's disease (AD) dementia, prodromal AD, and preclinical AD.Lower ALPS index predicted accelerated amyloid beta (Aβ) positron emission tomography (PET) burden and Aβ‐positive transition.The decrease in the ALPS index occurs before cerebrospinal fluid Aβ42 reaches the positive threshold.ALPS index predicted brain atrophy, clinical progression, and cognitive decline.Aβ PET and brain atrophy mediated the link of ALPS index with cognitive decline. [ABSTRACT FROM AUTHOR]

Healthy lifestyle might alleviate the socioeconomic inequities in health, but the extent of the joint and interactive effects of these two factors on dementia are unclear. This study aimed to detect the joint and interactive associations of socioeconomic status (SES) and lifestyle factors with incident dementia risk, and the underlying brain imaging alterations. Cox proportional hazards analysis was performed to test the joint and interactive associations. Partial correlation analysis was performed to reflect the brain imaging alterations. A total of 276,730 participants with a mean age of 55.9 (±8.0) years old from UK biobank were included. Over 8.5 (±2.6) years of follow-up, 3013 participants were diagnosed with dementia. Participants with high SES and most healthy lifestyle had a significantly lower risk of incident dementia (HR=0.19, 95% CI=0.14 to 0.26, P<2×10−16), Alzheimer's disease (AD, HR=0.19, 95% CI=0.13 to 0.29, P=8.94×10−15), and vascular dementia (HR=0.24, 95% CI=0.12 to 0.48, P=7.57×10−05) compared with participants with low SES and an unhealthy lifestyle. Significant interactions were found between SES and lifestyle on dementia (P=0.002) and AD (P=0.001) risks; the association between lifestyle and dementia was stronger among those of high SES. The combination of high SES and healthy lifestyle was positively associated with higher volumes in brain regions vulnerable to dementia-related atrophy. These findings suggest that SES and lifestyle significantly interact and influence dementia with its related brain structure phenotypes. [ABSTRACT FROM AUTHOR]

Background: Based on a longitudinal cohort design, the aim of this study was to investigate whether individual-based 18F fluorodeoxyglucose positron emission tomography (18F-FDG-PET) regional signals can predict dementia conversion in patients with mild cognitive impairment (MCI). Methods: We included 44 MCI converters (MCI-C), 38 non-converters (MCI-NC), 42 patients with Alzheimer's disease with dementia, and 40 cognitively normal controls. Data from annual cognitive measurements, 3D T1 magnetic resonance imaging (MRI) scans, and 18F-FDG-PET scans were used for outcome analysis. An individual-based FDG-PET approach was applied using seven volumes of interest (VOIs), Z transformed using a normal FDG-PET template. Hypometabolism was defined as a Z score < -2 of regional standard uptake value ratio. For the longitudinal cognitive test scores, generalized estimating equations were used. A linear mixed-effects model was used to compare the temporal impact of cortical hypometabolism and cortical thickness degeneration. Results: The clinical follow-up period was 6.6 ± 3.8 years (range 3.1 to 16.0 years). The trend of cognitive decline could differentiate MCI-C from MCI-NC after 3 years of follow-up. In the baseline 18F-FDG-PET scan of the patients with MCI, medial temporal lobe (MTL; 94.7% sensitivity, 80.5% specificity) and posterior cingulate cortex (PCC; 89.5% sensitivity, 73.1% specificity) hypometabolism predicted conversion with high accuracy. 18F-FDG-PET hypometabolism preceded dementia conversion at an interval of 3.70 ± 1.68 years and was earlier than volumetric changes, with the exception of the MTL. Conclusions: Our finding supports the use of individual-based 18F-FDG-PET analysis to predict MCI conversion to dementia. Reduced FDG-PET metabolism in the MTL and PCC were strongly associated with future cognitive decline in the MCI-C group. Changes in 18F-FDG-PET occurred 1 to 8 years prior to conversion to dementia. Progressive hypometabolism in the PCC, precuneus and lateral temporal lobe, but not MTL, preceded MRI findings at the MCI stage. [ABSTRACT FROM AUTHOR]

Identifying circulating metabolites associated with dementia, cognition, and brain volume may improve the understanding of dementia pathogenesis and provide novel insights for preventive and therapeutic interventions. This cohort study included a total of 87 885 participants (median follow‐up of 9.1 years, 54% female) without dementia at baseline from the UK Biobank. A total of 249 plasma metabolites were measured using nuclear magnetic resonance spectroscopy at baseline. Cox proportional regression was used to examine the associations of each metabolite with incident dementia (cases = 1134), Alzheimer's disease (AD; cases = 488), and vascular dementia (VD; cases = 257) during follow‐up. Dementia‐associated metabolites were further analyzed for association with cognitive deficits (N = 87 885) and brain volume (N = 7756) using logistic regression and linear regression. We identified 26 metabolites associated with incident dementia, of which 6 were associated with incident AD and 5 were associated with incident VD. These 26 dementia‐related metabolites were subfractions of intermediate‐density lipoprotein, large low‐density lipoprotein (L‐LDL), small high‐density lipoprotein (S‐HDL), very‐low‐density lipoprotein, fatty acids, ketone bodies, citrate, glucose, and valine. Among them, the cholesterol percentage in L‐LDL (L‐LDL‐C%) was associated with lower risk of AD (HR [95% CI] = 0.92 [0.87–0.97], p = 0.002), higher brain cortical (β = 0.047, p = 3.91 × 10−6), and hippocampal (β = 0.043, p = 1.93 × 10−4) volume. Cholesteryl ester–to–total lipid ratio in L‐LDL (L‐LDL‐CE%) was associated with lower risk of AD (HR [95% CI] = 0.93 [0.90–0.96], p = 1.48 × 10−4), cognitive deficits (odds ratio = 0.98, p = 0.009), and higher hippocampal volume (β = 0.027, p = 0.009). Cholesteryl esters in S‐HDL (S‐HDL‐CE) were associated with lower risk of VD (HR [95% CI] = 0.81 [0.71–0.93], p = 0.002), but not AD. Taken together, circulating levels of L‐LDL‐CE% and L‐LDL‐C% were robustly associated with risk of AD and AD phenotypes, but not with VD. S‐HDL‐CE was associated with lower risk of VD, but not with AD or AD phenotypes. These metabolites may play a role in the advancement of future intervention trials. Additional research is necessary to gain a complete comprehension of the molecular mechanisms behind these associations. [ABSTRACT FROM AUTHOR]

Background: The diffusion tensor imaging analysis along the perivascular space (ALPS)‐index can be used to model the glymphatic system in vivo. Aim: This study explores putative mechanisms between prediction of ALPS‐index and cognitive outcomes in young‐onset Alzheimer's disease (YOAD) and age‐matched controls (CTLs) and analyzes whether the link was mediated by the integrity of ALPS‐index‐anchored cerebral gray matter (GM). Methods: We enrolled 130 patients with YOAD and 137 CTLs. All participants underwent three‐dimensional T1‐weighted MRI, diffusion tensor imaging and cognitive tests. We constructed GM regions correlated with the ALPS‐index in the YOAD and CTL groups. For the GM regions significantly correlated with the ALPS‐index and cognitive measures, we extracted a 4‐mm radius sphere. In the YOAD and CTL groups, we used mediator analysis to explore the ALPS‐index as predictor, GM partitions as mediators, and significant cognitive test scores as outcomes. Results: Patient group had significantly lower ALPS‐index. The ALPS‐index was associated with GM volume in the cerebellar gray, dorsolateral prefrontal, thalamus, superior frontal, amygdala and hippocampus, and these coherent regions coincided with those showing GM atrophy in the YOAD group. Mediation analysis of the YOAD group suggested that the relationships between the ALPS‐index and cognitive performance were fully mediated by the integrity of ALPS‐index coherent GM areas. Discussion: Reserved GM mediates the link between the glymphatic system and cognition. Our findings suggest that GM integrity rather than the glymphatic system could serve as a direct cognitive test scores predictor in patients with YOAD. [ABSTRACT FROM AUTHOR]

Introduction: Grip strength and walking pace have been linked to cognitive dysfunction. Their relationships, however, demand further clarification as the evidence is derived primarily from less‐comprehensive investigations. Methods: A total of 340212 UK Biobank participants without dementia and cardiovascular diseases at baseline were analyzed. Cox proportional hazard models assessed the longitudinal associations. Results: Over a mean follow‐up of 8.51 ± 2.68 years, 2424 incident dementia cases were documented. A 5 kg increment of absolute grip strength was associated with lower risks of all‐cause dementia (hazard ratio [HR] 0.857), Alzheimer's disease (HR 0.874), and vascular dementia (HR 0.788). The patterns of associations remained similar when grip strength was expressed in relative terms and quintiles. A slow walking pace demonstrated consistent associations with increased risks of all dementia types. Discussion: Our findings provide amplified evidence and suggest that muscle fitness, reflected by objective grip strength measures and self‐reported walking pace, may be imperative for estimating the risks of dementia. [ABSTRACT FROM AUTHOR]

Background: A better understanding of factors associated with caregiver burden might facilitate the construction of coping strategies to improve their clinical outcomes and the comprehensive care model for dementia. Objective: To investigate the cognitive and neuropsychiatric domains that contribute to caregiver burden in three types of neurodegenerative disorders: Parkinson's disease (PD), Alzheimer's disease (AD), and frontotemporal disease (FTD). Methods: Eight hundred and fourteen patients and their caregivers were invited to participate; among them, 235 had PD with cognitive impairment; 429 had AD, and 150 had FTD. The evaluation protocol included the Neuropsychiatric Inventory (NPI), the Mini-Mental State Examination, the Chinese Version Verbal Learning Test, the modified Trail Making Test B, semantic fluency, and a geriatric depression score. Statistical comparisons of the cognitive tests, NPI total scores, and caregiver burden among the three diagnosed types of dementia, matched for a Clinical Dementia Rating (CDR) of 0.5 or 1, were performed, and multivariate linear regression models were used to evaluate the parameter significance. Results: Caregivers for patients with PD and FTD showed significant burden increments when the CDR scores changes from 0.5 to 1. For CDR = 0.5, the PD group had significantly lower caregiver burdens than the AD group, but the NPI total scores were significantly higher. Factors related to caregiver burden were the presence of delusion among all diagnosis groups, while the impact of NPI total scores related to caregiver burden was the highest in FTD, followed by AD and PD. Conclusions: At the mild to moderate stages, our results suggested different degrees of significance in terms of the cognitive test scores or NPI subdomains for predicting caregiver stress among the three types of dementia. [ABSTRACT FROM AUTHOR]

Dietary pattern (DP) results in nutrition adequacy and may influence cognitive decline and cortical atrophy in Alzheimer's disease (AD). The study explored DP in 248 patients with AD. Two neurobehavioral assessments (intervals 13.4 months) and two cortical thickness measurements derived from magnetic resonance images (intervals 26.5 months) were collected as outcome measures. Reduced rank regression was used to assess the groups of DPs and a linear mixed-effect model to explore the cortical neurodegenerative patterns. At screening, underweight body mass index (BMI) was related to significant higher lipid profile, impaired cognitive function, smaller cortical thickness, lower protein DP factor loading scores and the non-spouse caregiver status. Higher mini-mental state examination (MMSE) scores were related to the DP of coffee/tea, compared to the lipid/sugar or protein DP group. The underweighted-BMI group had faster cortical thickness atrophy in the pregenual and lateral temporal cortex, while the correlations between cortical thickness degeneration and high HbA1C or low B12 and folate levels were localized in the medial and lateral prefrontal cortex. The predictive model suggested that factors related to MMSE score were related to the caregiver status. In conclusion, normal or overweight BMI, coffee/tea DP group and living with a spouse were considered as protective factors for better cognitive outcomes in patients with AD. The influence of glucose, B12 and folate on the cortical degeneration was spatially distinct from the pattern of AD degeneration. [ABSTRACT FROM AUTHOR]

Background: Previous studies have reported inconsistent associations between chronic kidney disease (CKD) and dementia.Objective: To evaluate whether CKD is a risk factor for dementia and compare the performance of different measures of calculating estimated glomerular filtration rate (eGFR).Methods: 275,167 participants from UK Biobank were included and eGFR at baseline was calculated using serum creatinine (eGFRcr), cystatin C (eGFRcys), and creatinine-cystatin C equations (eGFRcr-cys). Restricted cubic splines and Cox regression models were performed to assess the relationship of eGFR with all-cause dementia, Alzheimer's disease (AD), and vascular dementia (VaD).Results: We observed a U-shaped relationship between each eGFR and risk of all-cause dementia and VaD, with eGFRcys and eGFRcr-cys showing a closer linkage (peGFRcys <0.0001, peGFRcrhboxcys<0.0001 and peGFRcr = 0.0001). Lower and supranormal eGFR were related to increased risk of all-cause dementia. Compared to the reference category of 90-104 ml/min/1.73 m2, adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) of all-cause dementia for eGFRcr-cys 30-59, <30, and ≥105 ml/min/1.73 m2 were 1.26 (95% CI [1.05-1.50], p = 0.012), 2.62 (95% CI [1.54-4.47], p < 0.001), and 1.41 (95% CI [1.17-1.70], p < 0.001). No statistically significant association was observed between eGFR with risk of AD.Conclusion: This prospective study identified impaired kidney function as a critical risk factor for dementia and noted the application of cystatin C strengthened the relationship between CKD and dementia, underlining the significant value of preserving kidney function to reduce the risk of dementia and considering cystatin C measurement as part of clinical practice. [ABSTRACT FROM AUTHOR]

Background: In light of advancements in machine learning techniques, many studies have implemented machine learning approaches combined with data measures to predict and classify Alzheimer's disease. Studies that predicted cognitive status with longitudinal follow-up of amyloid-positive individuals remain scarce, however. Objective: We developed models based on voxel-wise functional connectivity (FC) density mapping and the presence of the ApoE4 genotype to predict whether amyloid-positive individuals would experience cognitive decline after 1 year. Methods: We divided 122 participants into cognitive decline and stable cognition groups based on the participants' change rates in Mini-Mental State Examination scores. In addition, we included 68 participants from Alzheimer's Disease Neuroimaging Initiative (ADNI) database as an external validation data set. Subsequently, we developed two classification models: the first model included 99 voxels, and the second model included 99 voxels and the ApoE4 genotype as features to train the models by Wide Neural Network algorithm with fivefold cross-validation and to predict the classes in the hold-out test and ADNI data sets. Results: The results revealed that both models demonstrated high accuracy in classifying the two groups in the hold-out test data set. The model for FC demonstrated good performance, with a mean F 1-score of 0.86. The model for FC combined with the ApoE4 genotype achieved superior performance, with a mean F 1-score of 0.90. In the ADNI data set, the two models demonstrated stable performances, with mean F 1-scores of 0.77 in the first and second models. Conclusion: Our findings suggest that the proposed models exhibited promising accuracy for predicting cognitive status after 1 year in amyloid-positive individuals. Notably, the combination of FC and the ApoE4 genotype increased prediction accuracy. These findings can assist clinicians in predicting changes in cognitive status in individuals with a high risk of Alzheimer's disease and can assist future studies in developing precise treatment and prevention strategies. [ABSTRACT FROM AUTHOR]

Background: Metabolomics is a promising approach that can be used to understand pathophysiological pathways of Alzheimer's disease (AD). However, the causal relationships between metabolism and AD are poorly understood.Objective: We aimed to investigate the causal association between circulating metabolites and risk of AD through two-sample Mendelian randomization (MR) approach.Methods: Genetic associations with 123 circulating metabolic traits were utilized as exposures. Summary statistics data from International Genomics of Alzheimer's Project was used in primary analysis, including 21,982 AD cases and 41,944 controls. Validation was performed using family history of AD data from UK Biobank (27,696 cases of maternal AD, 14,338 cases of paternal AD, and 272,244 controls). We utilized inverse-variance weighted method as primary method.Results: We found significantly increased risks of developing AD per standard deviation increase in the levels of circulating ApoB (odd ratio[OR] = 3.18; 95% confidence interval[CI]: 1.52-6.66, p = 0.0022), glycoprotein acetyls (OR = 1.21; 95% CI: 1.05-1.39, p = 0.0093), total cholesterol (OR = 2.73; 95% CI: 1.41-5.30, p = 0.0030), and low-density lipoprotein (LDL) cholesterol (OR = 2.34; 95% CI: 1.53-3.57, p = 0.0001). Whereas glutamine (OR = 0.81; 95% CI: 0.71-0.92, p = 0.0011) were significantly associated with lower risk of AD. We also detected causal effects of several different composition of LDL fractions on increased AD risk, which has been verified in validation. However, we found no association between circulating high-density lipoprotein cholesterol and AD.Conclusion: Our findings suggest causal effects of circulating glycoprotein acetyls, ApoB, LDL cholesterol, and serum total cholesterol on higher risk of AD, whereas glutamine showed the protective effect. [ABSTRACT FROM AUTHOR]

Background: Recent studies had explored that gut microbiota was associated with neurodegenerative diseases (including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS)) through the gut-brain axis, among which metabolic pathways played an important role. However, the underlying causality remained unclear.Objective: Our study aimed to evaluate potential causal relationships between gut microbiota, metabolites, and neurodegenerative diseases through Mendelian randomization (MR) approach.Methods: We selected genetic variants associated with gut microbiota traits (N = 18,340) and gut microbiota-derived metabolites (N = 7,824) from genome-wide association studies. Summary statistics of neurodegenerative diseases were obtained from IGAP (AD, 17,008 cases; 37,154 controls), IPDGC (PD, 37,688 cases; 141,779 controls), and IALSC (ALS, 20,806 cases; 59,804 controls) respectively.Results: Greater abundance of Ruminococcus (OR, 1.245; 95% CI, 1.103-1.405; p = 0.0004) was found significantly related to higher risk of ALS. Besides, our study found suggestive associations of Actinobacteria, Lactobacillaceae, Faecalibacterium, Ruminiclostridium, and Lachnoclostridium with AD, of Lentisphaerae, Lentisphaeria, Oxalobacteraceae, Victivallales, Bacillales, Eubacteriumhalliigroup, Anaerostipes, and Clostridiumsensustricto1 with PD, and of Lachnospira, Fusicatenibacter, Catenibacterium, and Ruminococcusgnavusgroup with ALS. Our study also revealed suggestive associations between 12 gut microbiome-dependent metabolites and neurodegenerative diseases. Glutamine was related to lower risk of AD. For the serotonin pathway, serotonin was found as a protective factor of PD, while kynurenine as a risk factor for ALS.Conclusion: Our study firstly applied a two-sample MR approach to detect causal relationships among gut microbiota, gut metabolites, and neurodegenerative diseases. Our findings may provide new targets for treatments and may offer valuable insights for further studies on the underlying mechanisms. [ABSTRACT FROM AUTHOR]

Background: Subjective cognitive decline (SCD) might occur at the early stages of dementia. Individuals with SCD have an increased risk of subsequent objective cognitive decline and greater rates of progression to dementia.Objective: We aimed to explore the associations between SCD and cerebrospinal fluid (CSF) biomarkers of Alzheimer's disease (AD) pathology in cognitively normal individuals.Methods: A total of 1,099 cognitively normal elders with available data on CSF biomarkers of AD pathology (Aβ42, P-tau, and T-tau) were included in our analysis. Linear regression was used to examine the associations of SCD status and SCD severity with CSF biomarkers. Additionally, a review was conducted to discuss the associations between SCD and CSF biomarkers of AD pathology.Results: After adjustments for covariates, SCD and SCD severity showed significant associations with CSF Aβ42 (SCD: β= -0.0003, p = 0.0263; SCD severity: β= -0.0004, p = 0.0046), CSF T-tau/Aβ42 ratio (SCD: β= 0.1080, p = 0.0064; SCD severity: β= 0.1129, p = 0.0009) and CSF P-tau/Aβ42 ratio (SCD: β= 0.0167, p = 0.0103; SCD severity: β= 0.0193, p = 0.0006) rather than T-tau and P-tau compared with cognitively normal individuals. In the review, a total of 28 studies were finally included after reviewing 174 articles. CSF Aβ42 was lower in SCD than cognitively normal (CN) individuals, but higher than those with objective cognitive decline. However, CSF tau pathology showed no difference between SCD and CN.Conclusion: The results indicated that pathophysiological changes in CSF Aβ pathology occurred in individuals with SCD, which provide new insights into early intervention of AD. [ABSTRACT FROM AUTHOR]

The cognitive manifestations of Alzheimer's disease (AD) are related to brain network degeneration, and genetic differences may mediate network degeneration. Several AD-susceptible loci have been reported to involve amyloid or tau cascades; however, their relationships with gray matter (GM) volume and cognitive outcomes have yet to be established. We hypothesized that single-nucleotide polymorphism genotype groups may interact with apolipoprotein E4 (ApoE4) status or independently exert an effect on cognitive outcomes. We also hypothesized that GM structural covariance networks (SCNs) may serve as an endophenotype of the genetic effect, which, in turn, may be related to neurobehavior test scores. Gray matter SCNs were constructed in 324 patients with AD using T1 magnetic resonance imaging with independent component analysis (ICA). We assessed the effects of 15 genetic loci (rs9349407, rs3865444, rs670139, rs744373, rs3851179, rs11136000, rs3764650, rs610932, rs6887649, rs7849530, rs4866650, rs3765728, rs34011, rs6656401, and rs597668) using additive, recessive, and dominant models on cognitive outcomes. Statistical analysis was performed to explore the independent role of each locus, interactions with ApoE4 status, and relationships to GM ICA network intensity score. For outcome measures, we used the Mini-Mental State Examination (MMSE), Cognitive Abilities Screening Instrument (CASI) total score, and short-term memory (STM) subscores, adjusted for the covariates of education, disease duration, and age. Clinically, the CD2AP G allele showed a protective role in MMSE, CASI total, and CASI-STM scores independently or via interactions with non- ApoE4 status, while the CR1 A genotype group was associated with lower STM subscores independent of ApoE4 status. Three loci showed synergic interactions with ApoE4 : BIN 1, MS4A6A , and FTMT. Of the 15 meaningful ICA components, 5 SCNs (anterior and posterior hippocampus, right temporal, left thalamus, default mode network) showed relationships with general cognitive performance, in which only the ApoE4 and MS4A6A genotype groups were independently related to the hippocampus network. The genetic loci MS4A6A, BIN1, CLU, CR1, BIN1, PICALM , and FGF1 influenced the networks independently or in synergy. This study suggests that AD-susceptible loci may each exert clinical significance independently through interactions with ApoE4 status or through SCNs as an endophenotype and that this effect is associated with the cognitive outcomes. [ABSTRACT FROM AUTHOR]

The associations between obesity and Alzheimer's disease (AD) at different ages have been debated. Recent evidence implied the protective effects of metabolically healthy obesity on AD. We hypothesized that obesity and lipids could mitigate the detrimental impacts of AD pathological changes among metabolically healthy individuals in late life. In this study, a total of 604 metabolically healthy participants with normal cognition were included from the Chinese Alzheimer's Biomarker and LifestylE (CABLE) database. Multiple linear regression models were used to test the associations of body mass index (BMI) or lipids with cerebrospinal fluid (CSF) biomarkers after adjustment for age, gender, education, and Apolipoprotein E‐ɛ4 (APOE‐ɛ4). The results showed the lower CSF levels of total tau protein (t‐tau: p =.0048) and phosphorylated tau protein (p‐tau: p =.0035) in obese participants than in non‐obese participants, even after correcting for covariates. Moreover in late life, higher BMI was associated with decreased CSF t‐tau (β: −0.15, p =.0145) and p‐tau (β: −0.17, p =.0052). As for lipids, higher levels of total cholesterol (TC) and low‐density lipoprotein cholesterol (LDL‐C) were associated with decreased CSF t‐tau (TC: β: −0.16, p =.0115; LDL‐C: β: −0.16, p =.0082) and p‐tau (TC: β: −0.15, p =.0177; LDL‐C: β: −0.14, p =.0225) in obese participants. Furthermore, these associations were only significant in participants with late‐life obesity and APOE‐ɛ4 non‐carriers. Overall, in a cognitively normal population, we found metabolically healthy obesity and lipids in late life might be protective factors for neurodegenerative changes. [ABSTRACT FROM AUTHOR]

Background: The National Institute on Aging and Alzheimer's Association proposed an ATN classification system which divided Alzheimer's disease biomarkers into three binary classes: amyloid deposition (A), tauopathy (T), and neurodegeneration or neuronal injury (N).Objective: To estimate the prevalence of each profile and to describe the demographic characteristics of each group in Chinese cognitively intact older adults.Methods: In this cross-sectional study, 561 cognitively intact participants from the Chinese Alzheimer's Biomarker and LifestylE (CABLE) study were classified into eight groups using cerebrospinal fluid amyloid-β 42/40 as A, phosphorylated tau as T, and total tau as N. Multinomial models were used to determine the estimated prevalence of the eight groups.Results: The number and proportion of 561 participants in each ATN profile were 254 A-T-N- (45.3%), 28 A-T+N- (5.0%), 21 A-T-N+ (3.7%), 71 A-T+N+ (12.7%), 78 A + T-N- (13.9%), 14 A + T+N- (2.5%), 21 A + T-N+ (3.7%), and 74 A + T+N+ (13.2%). Individuals in N+ groups tend to be older than N- groups. A+ groups included more female individuals. The prevalence of A-T-N- profile declined with age, while that of A + T+N+ increased continuously.Conclusion: This is the first work to estimate the prevalence of each ATN profile and describe the demographic characteristics of ATN profiles based on a Chinese cohort. The clinical implications of our findings need to be scrutinized further in longitudinal studies of the ATN classification system. [ABSTRACT FROM AUTHOR]

Reversion from mild cognitive impairment (MCI) to normal cognition (NC) is not uncommon and indicates a better cognitive trajectory. This study aims to identify predictors of MCI reversion and develop a predicting model. A total of 391 MCI subjects (mean age = 74.3 years, female = 61 %) who had baseline data of magnetic resonance imaging, clinical, and neuropsychological measurements were followed for two years. Multivariate logistic analyses were used to identify the predictors of MCI reversion after adjusting for age and sex. A stepwise backward logistic regression model was used to construct a predictive nomogram for MCI reversion. The nomogram was validated by internal bootstrapping and in an independent cohort. In the training cohort, the 2-year reversion rate was 19.95 %. Predictors associated with reversion to NC were higher education level (p = 0.004), absence of APOE 4 allele (p = 0.001), larger brain volume (p < 0.005), better neuropsychological measurements performance (p < 0.001), higher glomerular filtration rate (p = 0.035), and lower mean arterial pressure (p = 0.060). The nomogram incorporating five predictors (education, hippocampus volume, the Alzheimer's Disease Assessment Scale-Cognitive score, the Rey Auditory Verbal Learning Test-immediate score, and mean arterial pressure) achieved good C-indexes of 0.892 (95 % confidence interval [CI], 0.859–0.926) and 0.806 (95 % CI, 0.709–0.902) for the training and validation cohort. Observational duration is relatively short; The predicting model warrant further validation in larger samples. This prediction model could facilitate risk stratification and early management for the MCI population. • The 2-year reversion rate from MCI to NC was 19.95%. • Predictors of reversion included education, APOE4 allele, brain volume, neuropsychological tests performance, eGFR, and MAP. • The predicting model achieved good performance for the training and validation cohort. [ABSTRACT FROM AUTHOR]

Our previous studies showed that the transcription factor early growth response‐1 (EGR1) may play a role in keeping the brain cholinergic function intact in the preclinical stages of Alzheimer's disease (AD). In order to elucidate the mechanisms involved, we first performed data mining on our previous microarray study on postmortem human prefrontal cortex (PFC) for the changes in the expression of EGR1 and acetylcholinesterase (AChE) and the relationship between them during the course of AD. The study contained 49 patients, ranging from non‐demented controls (Braak stage 0) to late AD patients (Braak stage VI). We found EGR1‐mRNA was high in early AD and decreased in late AD stages, while AChE‐mRNA was stable in preclinical AD and slightly decreased in late AD stages. A significant positive correlation was found between the mRNA levels of these two molecules. In addition, we studied the relationship between EGR1 and AChE mRNA levels in the frontal cortex of 3–12‐months old triple‐transgenic AD (3xTg‐AD) mice. EGR1‐ and AChE‐mRNA were lower in 3xTg‐AD mice compared with wild‐type (WT) mice. A significant positive correlation between these two molecules was present in the entire group and in each age group of either WT or 3xTg‐AD mice. Subsequently, AChE expression was determined following up‐ or down‐regulating EGR1 in cell lines and the EGR1 levels were found to regulate AChE at both the mRNA and protein levels. Dual‐luciferase assay and electrophoretic mobility shift assay in the EGR1‐overexpressing cells were performed to determine the functionally effective binding sites of the EGR1 on the AChE gene promoter. We conclude that the EGR1 can upregulate AChE expression by a direct effect on its gene promoter, which may contribute significantly to the changes in cholinergic function in the course of AD. The 3xTg‐AD mouse model only reflects later stage AD. [ABSTRACT FROM AUTHOR]

Decline in executive function (EF) occurs early in Alzheimer’s disease (AD) and can interfere with daily functioning. Unfortunately, little is known about the relative ability of traditional EF tests to detect these cognitive changes. Given that timely diagnosis and intervention are essential to improving functional outcome in this population, our aim was to identify the specific EF measures that best differentiated mild dementia from normal aging. Thirty-one patients with mild AD and 31 controls were administered 7 EF tests. Findings indicated significant between-group differences on all measures except Wisconsin Card Sorting Test. The remaining 6 tests displayed fair to good accuracy discriminating between AD cases and controls. Only category fluency and Tower of London test remained in the final regression model that yielded the highest AUC of 0.90, which was not statistically different from that of either test alone. Overall, most of the tests employed were valid for assessing mild EF disturbances. Specifically, the two measures can be used in isolation for quick screening or in combination to facilitate a more in-depth evaluation of EF performance. This study contributes to clinical field by testifying to the validity of various EF tests to identify AD-related compromises in this cognitive domain. [ABSTRACT FROM PUBLISHER]

Background: Inflammatory processes play a pivotal role in the degenerative process of Alzheimer's disease. In humans, a biallelic (C/T) polymorphism in the promoter region (position-511) (rs16944) of the interleukin-1 beta gene has been significantly associated with differences in the secretory capacity of interleukin-1 beta. In this study, we investigated whether this functional polymorphism mediates the brain networks in patients with Alzheimer's disease.Methods: We enrolled a total of 135 patients with Alzheimer's disease (65 males, 70 females), and investigated their gray matter structural covariance networks using 3D T1 magnetic resonance imaging and their white matter macro-structural integrities using fractional anisotropy. The patients were classified into two genotype groups: C-carriers (n = 108) and TT-carriers (n = 27), and the structural covariance networks were constructed using seed-based analysis focusing on the default mode network medial temporal or dorsal medial subsystem, salience network and executive control network. Neurobehavioral scores were used as the major outcome factors for clinical correlations.Results: There were no differences between the two genotype groups in the cognitive test scores, seed, or peak cluster volumes and white matter fractional anisotropy. The covariance strength showing C-carriers > TT-carriers was the entorhinal-cingulum axis. There were two peak clusters (Brodmann 6 and 10) in the salience network and four peak clusters (superior prefrontal, precentral, fusiform, and temporal) in the executive control network that showed C-carriers < TT-carriers in covariance strength. The salience network and executive control network peak clusters in the TT group and the default mode network peak clusters in the C-carriers strongly predicted the cognitive test scores.Conclusions: Interleukin-1 beta C-511 T polymorphism modulates the structural covariance strength on the anterior brain network and entorhinal-interconnected network which were independent of the white matter tract integrity. Depending on the specific C-511 T genotype, different network clusters could predict the cognitive tests. [ABSTRACT FROM AUTHOR]

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Under homeostatic conditions, sequential cleavage of amyloid precursor protein by β-site cleaving enzyme and γ-secretase forms the common Aβ isoforms, Aβ1-38, Aβ1-40, and Aβ1-42. • However, in the pathological Alzheimer's disease (AD) state, Aβ clearance is decreased nearly 30%. As such, γ-secretase is a promising drug target for AD therapy, as a decrease in its enzymatic activity has the potential to reduce Aβ levels and modify disease. • In contrast, current treatments for AD provide only short term symptomatic relief. WHAT THIS STUDY ADDS • Unique among previous studies of γ-secretase inhibitors (GSIs), such as semagacestat and begacestat, our results showed that avagacestat, an oral GSI in clinical development for the disease-modifying treatment of AD, decreased Aβ1-40 plasma concentrations and was well-tolerated in both young and elderly subjects, with adverse events being predominantly mild to moderate in severity. AIM To evaluate the single dose pharmacokinetics, pharmacodynamics, and preliminary tolerability of the γ-secretase inhibitor BMS-708163 (avagacestat) in young and elderly men and women. METHODS All subjects received double-blinded administration of a single 50 mg dose of avagacestat in capsule form or matching placebo. Main evaluations included pharmacokinetics, safety, plasma amyloid-β (Aβ)1-40 concentratios and exploration of Notch biomarkers. RESULTS Avagacestat 50 mg capsule was well tolerated and rapidly absorbed among young and elderly subjects, with a median tmax between 1 and 2 h post dose and an average half-life between 41 and 71 h. In general, subjects aged 75 years or more had higher AUC(0,∞) values than those aged less than 75 years. An exploratory analysis of Aβ1-40 serum concentrations showed a pattern of decreasing concentrations over the first 4-6 h followed by a rise above baseline that was maintained until the end of the assessment period. Adverse events were generally mild, occurring more frequently in elderly subjects, with no observed difference between subjects receiving avagacestat and placebo. No dose limiting gastrointestinal effects of avagacestat were observed and exploratory biomarkers of Notch inhibition did not change significantly. CONCLUSIONS The favourable safety profile and pharmacokinetic effects of avagacestat in this study support its continued development, especially in the target population of elderly subjects with mild cognitive impairment or Alzheimer's disease. [ABSTRACT FROM AUTHOR]

Background: The concentration of amyloid β (Aβ) peptides in cerebrospinal fluid (CSF) is a biomarker for Alzheimer’s disease (AD) pathology, and has been used to evaluate the effectiveness of γ-secretase inhibition. Avagacestat is a selective γ-secretase inhibitor in development for the treatment of AD. The primary objective of this study was to assess the effects of single oral doses of avagacestat on the CSF Aβ concentrations in healthy male subjects. Secondary objectives included single-dose pharmacokinetics in CSF and plasma, safety and tolerability. Methods: This was a double-blind, placebo-controlled, randomized, single-dose study. Healthy male subjects were assigned to one of three sequential avagacestat dose panels (50, 200 and 400 mg) or placebo as single oral doses. Results: 34 subjects were enrolled. Administration of a single dose of 200 or 400 mg of avagacestat resulted in a marked decrease in CSF Aβ 1–38, Aβ 1–40 and Aβ 1–42 concentrations vs placebo; with smaller decreases observed in the 50 mg dose group. Avagacestat was quickly absorbed into the systemic circulation, with a mean time to reach maximum plasma concentration (t max) of approximately 1–2 h, and a CSF t max of approximately 3 h. Adverse events were uncommon and occurred with similar frequency in the placebo and avagacestat groups. Conclusion: Avagacestat was safe, well tolerated, and resulted in a notable decrease in CSF Aβ concentrations, suggestive of γ-secretase inhibition. The results warrant further clinical study in patients with AD. [ABSTRACT FROM AUTHOR]

Expression of somatostatin in the brain declines during aging in various mammals including apes and humans. A prominent decrease in this neuropeptide also represents a pathological characteristic of Alzheimer disease. Using in vitro and in vivo paradigms, we show that somatostatin regulates the metabolism of amyloidßpeptide (Aß), the primary pathogenic agent of Alzheimer disease, in the brain through modulating proteolytic degradation catalyzed by neprilysin. Among various effector candidates, only somatostatin upregulated neprilysin activity in primary cortical neurons. A genetic deficiency of somatostatin altered hippocampal neprilysin activity and localization, and increased the quantity of a hydrophobic 42-mer form of Aß, Aß42, in a manner similar to presenilin gene mutations that cause familial Alzheimer disease. These results indicate that the aging-induced downregulation of somatostatin expression may be a trigger for Aßaccumulation leading to late-onset sporadic Alzheimer disease, and suggest that somatostatin receptors may be pharmacological-target candidates for prevention and treatment of Alzheimer disease. [ABSTRACT FROM AUTHOR]

The pathological role of vitamin K2 in Alzheimer's disease (AD) involves a definite link between impaired cognitive functions and decreased serum vitamin K levels. Vitamin K2 supplementation may have a protective effect on AD. However, the mechanism underlying vitamin K2 protection has not been elucidated. With the amyloid-β (Aβ) cascade hypothesis, we constructed a clone containing the C-terminal fragment of amyloid precursor protein (β-CTF/APP), transfected in astroglioma C6 cells and used this cell model (β-CTF/C6) to study the protective effect of vitamin K2 against Aβ cytotoxicity. Both cellular and biochemical assays, including cell viability and reactive oxygen species (ROS), assays assay, and Western blot and caspase activity analyses, were used to characterize and unveil the protective role and mechanism of vitamin K2 protecting against Aβ-induced cytotoxicity. Vitamin K2 treatment dose-dependently decreased the death of neural cells. The protective effect of vitamin K2 could be abolished by adding warfarin, a vitamin K2 antagonist. The addition of vitamin K2 reduced the ROS formation and inhibited the caspase-3 mediated apoptosis induced by Aβ peptides, indicating that the mechanism underlying the vitamin K2 protection is likely against Aβ-mediated apoptosis. Inhibitor assay and Western blot analyses revealed that the possible mechanism of vitamin K2 protection against Aβ-mediated apoptosis might be via regulating phosphatidylinositol 3-kinase (PI3K) associated-signaling pathway and inhibiting caspase-3-mediated apoptosis. Our study demonstrates that vitamin K2 can protect neural cells against Aβ toxicity. [ABSTRACT FROM AUTHOR]

The glycine zipper motif at the C-terminus of the β-amyloid (Aβ) peptide have been shown to strongly influence the formation of neurotoxic aggregates. A previous study showed that the G37L mutation dramatically reduces the Aβ toxicity in vivo and in vitro. However, the primary cause and mechanism of the glycine zipper motif on Aβ properties remain unknown. To gain molecular insights into the impact of glycine zipper on Aβ properties, we substituted the residue 37 of Glycine by Valine and studied the structural and biochemical properties of G37V mutation, Aβ42(37V), by using in vitro and in silico approaches. Unlike G37L mutation, the G37V mutation reduced toxicity substantially but did not significantly accelerate the aggregation rate or change the content of secondary structures. Further TEM analyses showed that the G37V mutation formed an ellipse-like aggregate rather than a network-like fibril as wild type or G37L mutation of Aβ42 form. This different aggregation morphology may be highly linked with the reduction of toxicity. To gain the insight for the different properties of Aβ42(37V), we studied the structure of Aβ42 and G37V mutation using the replica exchange molecular dynamics simulation. Our results demonstrate that although the overall secondary structure population is similar with Aβ42 and Aβ42(G37V), Aβ42(G37V) shows an increase in the β-turn and β-hairpin at residues 36–37 and the flexibility of the Asp23-Lys28 salt bridge. These unique structural features may be the possible reason to account for the ellipse-like morphology. • Aβ peptide forms a glycine zipper motif at residues G25, G29, G33 and GG37. • The glycine zipper motif has impacts on the Aβ aggregation and toxicity. • The replacement of Gly37 with Val leads to a change of the aggregation morphology and reduces toxicity. • The G37V mutation causes an increase of the β-turn at residues 36–37 and the flexibility at Asp23--Lys28 salt bridge. [ABSTRACT FROM AUTHOR]

Background: Neuropsychiatric symptoms (NPSs) are important aspects of Alzheimer's disease (AD). Investigation of the effect of functional network abnormalities on clustered NPSs may uncover loci of altered connectivity for more targeted pharmacological and behavioral interventions in AD. The study aimed to investigate functional connectivity in AD and the clustered NPSs, as assessed by the Neuropsychiatric Inventory (NPI).Methods: In one hundred and fifty-nine patients with mild dementia stage of AD, graph metrics measuring functional connectivity at global network- and local network-level were assessed by closeness-centrality, betweenness-centrality, average-path-length, local-efficiency, and clustering-coefficient, respectively. The relationship between the NPI composite score and functional connectivity was assessed.Results: In AD, an increase in behavioral composite score was associated with changes in functional connectivity at local network-level, and regions displayed the changes was left lingual gyrus, left sub-genual ACC nodes, and left supra-genual ACC nodes (P < 0.05). An increase in affective composite score was associated with changes in functional connectivity at global network-level, and regions displayed the change was right caudate (P = 0.014). An increase in psychotic composite score was associated with changes in functional connectivity at global network-level, and regions displayed the change was left precuneus and right dorsolateral superior frontal gyrus (P < 0.05).Limitations: Cognitively normal elderly subjects and longitudinal follow-up will be needed to see the evolution of NPS clusters and pathological changes in the functional connectivity at global or local network-level.Conclusions: Different NPS clusters corresponded to distinct changes in functional connectivity at global and local network-level. [ABSTRACT FROM AUTHOR]

• The ALPS index peaks at age 30. • The ALPS index has an age-dependent decrease in cognitively unimpaired individual. • A higher ALPS index in older people can reflect a greater cortical volume reserve. The glymphatic system is a fluid-clearance pathway that clears cerebral waste products, and its dysfunction has been associated with protein aggregation diseases such as Alzheimer's disease. To understand how the glymphatic system changes with aging, we enrolled 433 cognitive unimpaired participants (236 women and 197 men, 13–88 years) and evaluated the glymphatic function by calculating diffusion tensor imaging analysis along the perivascular space (ALPS) index and explored how the ALPS index is associated with cortical atrophy and cognitive decline in older people. We found a significant inverse correlation between ALPS index and age (ρ = −0.45, p < 0.001), with a peak value in people in their thirties. A higher ALPS index indicated a better cortical reserve in regions coincided with the default mode network. Declines in mental manipulation and short-term memory performance in the older participants were associated with a lower ALPS index and cortical atrophy in the amygdala, anterior and posterior cingulate, thalamus and middle frontal regions. Our findings highlight that the ALPS index could be used to evaluate brain reserve and cognitive reserve in older people. [ABSTRACT FROM AUTHOR]

Abstract: Background: γ-Secretase inhibitors (GSIs) are being investigated for their potential to modify the progression of Alzheimer disease based on their ability to regulate amyloid-β (Aβ) accumulation. BMS-708163 (avagacestat) is an oral GSI designed for selective inhibition of Aβ synthesis currently in development for the treatment of mild to moderate and predementia AD. In addition to the desired effect on Aβ synthesis, GSIs affect Notch processing, which is thought to mediate some toxic adverse effects reported with this drug class. Avagacestat produced up to 190-fold greater selectivity for Aβ synthesis than Notch processing in preclinical studies and may therefore produce less toxic adverse events than other less selective compounds. Presented here are the results of the first in-human study for this new GSI compound. Objective: The goal of this study was to assess the tolerability profile, pharmacokinetic properties, and effects on pharmacodynamic markers (Aβ, trefoil factor family 3 protein, dual specificity phosphatase 6, and hairy and enhancer of split-1) of single, oral doses of avagacestat in healthy, young, male volunteers. Methods: This was a multicenter, randomized, double-blind, placebo-controlled, single-ascending dose study in 8 healthy young men (age, 18–45 years) per dosing panel. Each study participant was randomized to receive a single dose of placebo (n = 2) or avagacestat (n = 6 for each dose) as an oral solution in 1 of 9 sequential dose panels (0.3, 1.5, 5, 15, 50, 100, 200, 400, and 800 mg). For determination of avagacestat, blood samples were obtained before dosing and for up to 144 hours after dosing. For participants in the 800-mg avagacestat dose panel, additional samples were obtained at 216, 312, and 648 hours. For 40–amino acid isoform of Aβ (Aβ1–40) assessment, plasma samples were collected before avagacestat administration and up to 72 hours after dosing. Results: Avagacestat concentrations peaked quickly after oral administration and then had a biphasic decrease in concentrations with a prolonged terminal phase. Exposures were proportional with doses up to 200 mg. Avagacestat was well tolerated at single oral doses up to 800 mg, with a biphasic effect on plasma Aβ1–40. Adverse events were predominately mild to moderate in severity with no evidence of dose dependence up to 200 mg. Conclusions: Results from this single-ascending dose study suggest that avagacestat was tolerated at a single-dose range of 0.3 to 800 mg and suitable for further clinical development. ClinicalTrials.gov identifier: NCT01454115. [Copyright &y& Elsevier]