Education in people's early lives are positively related to their cognitive function, but its modulating effects on detailed cognition domains, its interaction with leisure activities and the ...associated brain changes have yet to be investigated. This report used data from 659 cognitively normal community dwelling elderly who completed neuropsychological tests, leisure activities measurement, and 78 of them underwent structural and diffusion MRI scans. We found that: (i) the highly educated elderly had a better cognitive functioning in multi-domains, higher frequencies of participation in knowledge-related leisure activities, and slower age-related reductions of executive function; (ii) the intellectual and social types of leisure activities mediated the association between education and multiple cognitive domains, including memory, language, attention and executive function; (iii) there was a significant age by education interaction on the gray matter volume of the anterior brain regions and white matter integrity; and (iv) the interaction between age and education affected cognition indirectly through white matter integrity analyzed using structural equation model. Overall, our results revealed that high education in early life served as a protective factor in aging that may help to postpone cognitive and brain reserve decline in cognitively normal aging.
Objectives
To estimate the prevalence of mild cognitive impairment (MCI) in Beijing, China, and to explore the potential protective and risk factors for MCI.
Design
Population‐based survey.
Setting
...The Beijing Ageing Brain Rejuvenation Initiative (BABRI).
Participants
Participants randomly recruited from BABRI (N = 1,211).
Measurements
Participants underwent a battery of neuropsychological examinations to determine cognitive function and answered a series of personal questions. The prevalence of MCI and its subtypes were computed using Petersen's criteria. Influencing factors for MCI were estimated based on participant medical history, lifestyle, diet, and leisure activities.
Results
One thousand twenty (aged >55, mean 63.9 ± 6.6; 36.7% male) subjects completed the neuropsychological tests. The overall prevalence of MCI was 15.7%, with single‐domain amnestic, multiple‐domain amnestic, and nonamnestic subtype prevalences of 6.4%, 3.7%, and 5.6%, respectively. Eight hundred sixty‐four subjects were used for the case–control analysis. Hypertension, diabetes mellitus, and cerebrovascular disease were found to be associated with MCI. Healthy diet and greater involvement in physical, intellectual, and social activities were associated with a lower risk of MCI.
Conclusion
The prevalence of MCI was compatible with that found in previous published reports, and the information on the epidemiology of MCI, especially risk factors, may help to explore therapeutic strategies and preventive approaches to delay conversion to dementia.
Downregulation of brain-derived neurotrophic factor (BDNF) and its cognate neurotrophin receptor, TrkB, were observed during the progression of dementia, but whether the Alzheimer's disease (AD) ...pathological lesions diffuse plaques, (DPs), neuritic plaques (NPs), and neurofibrillary tangles (NFTs) are related to this alteration remains to be clarified.
Negative binomial (NB) regressions were performed using gene expression data accrued from a single population of CA1 pyramidal neurons and regional hippocampal dissections obtained from participants in the Rush Religious Orders Study (RROS).
Downregulation of Bdnf is independently associated with increased entorhinal cortex NPs. Downregulation of TrkB is independently associated with increased entorhinal cortex NFTs and CA1 NPs during the progression of AD.
Results indicate that BDNF and TrkB dysregulation contribute to AD neuropathology, most notably hippocampal NPs and NFTs. These data suggest attenuating BDNF/TrkB signaling deficits either at the level of BDNF, TrkB, or downstream of TrkB signaling may abrogate NPs and/or NFTs.
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•Negative binomial models associate Bdnf &TrkB levels with Alzheimer neuropathology.•CA1 neuron and hippocampal Bdnf &TrkB levels are similar in Alzheimer's disease.•Hippocampal Bdnf inversely correlates with entorhinal cortex neuritic plaques.•Hippocampal TrkB inversely correlates with entorhinal cortex neurofibrillary tangles.•Hippocampal TrkB inversely correlates with hippocampal CA1 neuritic plaques.
Summary Background We have previously characterised functional brain abnormalities in young adults at genetic risk for late-onset Alzheimer's disease. To gain further knowledge on the preclinical ...phase of Alzheimer's disease, we sought to characterise structural and functional MRI, CSF, and plasma biomarkers in a cohort of young adults carrying a high-penetrance autosomal dominant mutation that causes early-onset Alzheimer's disease. Methods Between January and August, 2010, 18–26-year-old presenilin 1 (PSEN1) E280A mutation carriers and non-carriers from the Colombian Alzheimer's Prevention Initiative Registry in Medellín Antioquia, Colombia, had structural MRI, functional MRI during associative memory encoding and novel viewing and control tasks, and cognitive assessments. Consenting participants also had lumbar punctures and venepunctures. Outcome measures were task-dependent hippocampal or parahippocampal activations and precuneus or posterior cingulate deactivations, regional grey matter reductions, CSF Aβ1–42 , total tau and phospho-tau181 concentrations, and plasma Aβ1–42 concentrations and Aβ1–42 :Aβ1–40 ratios. Structural and functional MRI data were compared using automated brain mapping algorithms and search regions related to Alzheimer's disease. Cognitive and fluid biomarkers were compared using Mann-Whitney tests. Findings 44 participants were included: 20 PSEN1 E280A mutation carriers and 24 non-carriers. The carrier and non-carrier groups did not differ significantly in their dementia ratings, neuropsychological test scores, or proportion of apolipoprotein E (APOE) ε4 carriers. Compared with non-carriers, carriers had greater right hippocampal and parahippocampal activation (p=0·001 and p<0·014, respectively, after correction for multiple comparisons), less precuneus and posterior cingulate deactivation (all p<0·010 after correction), and less grey matter in several parietal regions (all p<0·002 uncorrected and corrected p=0·009 in the right parietal search region). In the 20 participants (ten PSEN1 E280A mutation carriers and ten non-carriers) who had lumbar punctures and venepunctures, mutation carriers had higher CSF Aβ1–42 concentrations (p=0·008) and plasma Aβ1–42 concentrations (p=0·01) than non-carriers. Interpretation Young adults at genetic risk for autosomal dominant Alzheimer's disease have functional and structural MRI findings and CSF and plasma biomarker findings consistent with Aβ1–42 overproduction. Although the extent to which the underlying brain changes are either neurodegenerative or developmental remain to be determined, this study shows the earliest known biomarker changes in cognitively normal people at genetic risk for autosomal dominant Alzheimer's disease. Funding Banner Alzheimer's Foundation, Nomis Foundation, Anonymous Foundation, Forget Me Not Initiative, Boston University Department of Psychology, Colciencias, National Institute on Aging, National Institute of Neurological Disorders and Stroke, and the State of Arizona.
Abstract
Background
The identification of factors that specifically influence pathological and successful cognitive aging is a prerequisite for implementing disease prevention and promoting ...successful aging. However, multi-domain behavioral factors that characterize the difference between successful and pathological cognitive aging are not clear yet.
Methods
A group of community-dwelling older adults (
N
= 1347, aged 70-88 years) in Beijing was recruited in this cross-sectional study, and a sub-cohort was further divided into successful cognitive aging (SCA,
N
= 154), mild cognitive impairment (MCI,
N
= 256), and cognitively normal control (CNC,
N
= 173) groups. Analyses of variance, regression models with the Shapley value algorithm, and structural equation model (SEM) analyses were conducted to determine specific influencing factors and to evaluate their relative importance and interacting relationships in altering cognitive performance.
Results
We found that abundant early-life cognitive reserve (ECR, including the level of education and occupational attainment) and reduced late-life leisure activity (LLA, including mental, physical, and social activities) were distinct characteristics of SCA and MCI, respectively. The level of education, age, mental activity, and occupational attainment were the top four important factors that explained 31.6% of cognitive variability. By SEM analyses, we firstly found that LLA partially mediated the relationship between ECR and cognition; and further multi-group SEM analyses showed ECR played a more direct role in the SCA group than in the MCI group: in the SCA group, only the direct effect of ECR on cognition was significant, and in the MCI group, direct effects between ECR, LLA and cognition were all significant.
Conclusions
Results of this large-sample community-based study suggest it is important for older adults to have an abundant ECR for SCA, and to keep a high level of LLA to prevent cognitive impairment. This study clarifies the important rankings of behavioral characteristics of cognitive aging, and the relationship that ECR has a long-lasting effect on LLA and finally on cognition, providing efficient guidance for older adults to improve their cognitive function and new evidence to explain the heterogeneity of cognitive aging.
Abstract
Brain disconnection model has been proposed as a possible neural mechanism for cognitive aging. However, the relationship between structural connectivity degeneration and cognitive decline ...with normal aging remains unclear. In the present study, using diffusion MRI and tractography techniques, we report graph theory-based analyses of the brain structural connectome in a cross-sectional, community-based cohort of 633 cognitively healthy elderly individuals. Comprehensive neuropsychological assessment of the elderly subjects was performed. The association between age, brain structural connectome, and cognition across elderly individuals was examined. We found that the topological efficiency, modularity, and hub integration of the brain structural connectome exhibited a significant decline with normal aging, especially in the frontal, parietal, and superior temporal regions. Importantly, network efficiency was positively correlated with attention and executive function in elderly subjects and had a significant mediation effect on the age-related decline in these cognitive functions. Moreover, nodal efficiency of the brain structural connectome showed good performance for the prediction of attention and executive function in elderly individuals. Together, our findings revealed topological alterations of the brain structural connectome with normal aging, which provides possible structural substrates underlying cognitive aging and sensitive imaging markers for the individual prediction of cognitive functions in elderly subjects.
The mechanisms linking motor function to Alzheimer's disease (AD) progression have not been well studied, despite evidence of AD pathology within motor brain regions. Thus, there is a need for new ...motor measure that is sensitive and specific to AD.
In a sample of 121 older adults (54 cognitive unimpaired CU, 35 amnestic Mild Cognitive Impairment aMCI, and 32 probable mild AD), intrasubject standard deviation (ISD) across six trials of a novel upper-extremity motor task was predicted with volumetric regional gray matter and neuropsychological scores using classification and regression tree (CART) analyses.
Both gray matter and neuropsychological CART models indicated that motor task ISD (our measure of motor learning) was related to cortical regions and cognitive test scores associated with memory, executive function, and visuospatial skills. CART models also accurately distinguished motor task ISD of MCI and probable mild AD from CU.
Variability in motor task performance across practice trials may be valuable for understanding preclinical and early-stage AD.
•Our motor learning test may help screen for Alzheimer's Disease (AD).•Data justify studying variability of a motor assessment across multiple attempts.•Classification and regression tree (CART) analyses are valuable for aging research.•Future research will validate motor task variability against AD biomarkers.
Evidences from normal subjects suggest that the default-mode network (DMN) has posterior cingulate cortex (PCC), medial prefrontal cortex (MPFC) and inferior parietal cortex (IPC) as its hubs; ...meanwhile, these DMN nodes are often found to be abnormally recruited in Alzheimer's disease (AD) patients. The issues on how these hubs interact to each other, with the rest nodes of the DMN and the altered pattern of hubs with respect to AD, are still on going discussion for eventual final clarification.
To address these issues, we investigated the causal influences between any pair of nodes within the DMN using Granger causality analysis and graph-theoretic methods on resting-state fMRI data of 12 young subjects, 16 old normal controls and 15 AD patients respectively. We found that: (1) PCC/MPFC/IPC, especially the PCC, showed the widest and distinctive causal effects on the DMN dynamics in young group; (2) the pattern of DMN hubs was abnormal in AD patients compared to old control: MPFC and IPC had obvious causal interaction disruption with other nodes; the PCC showed outstanding performance for it was the only region having causal relation with all other nodes significantly; (3) the altered relation between hubs and other DMN nodes held potential as a noninvasive biomarker of AD.
Our study, to the best of our knowledge, is the first to support the hub configuration of the DMN from the perspective of causal relationship, and reveal abnormal pattern of the DMN hubs in AD. Findings from young subjects provide additional evidence for the role of PCC/MPFC/IPC acting as hubs in the DMN. Compared to old control, MPFC and IPC lost their roles as hubs owing to the obvious causal interaction disruption, and PCC was preserved as the only hub showing significant causal relations with all other nodes.
•New methods developed for the production of specific dephytylated chlorophyll standards.•ESI was more effective than APCI for dephytylated chlorophyll MS analysis.•By first time, 16 dephytylated ...chlorophylls have been analysed by high resolution-MS2.•New and specific MS2 reactions are described for particular dephytylated chlorophylls.•New functional groups at the isocyclic ring mean characteristic product ions.
Dephytylated chlorophylls (chlorophyllides and pheophorbides) are the starting point of the chlorophyll catabolism in green tissues, components of the chlorophyll pattern in storage/processed food vegetables, as well as the favoured structural arrangement for chlorophyll absorption. In addition, dephytylated native chlorophylls are prone to several modifications of their structure yielding pyro-, 132-hydroxy- and 151-hydroxy-lactone derivatives. Despite of these outstanding remarks only few of them have been analysed by MSn. Besides new protocols for obtaining standards, we have developed a new high throughput methodology able to determine the fragmentation pathway of 16 dephytylated chlorophyll derivatives, elucidating the structures of the new product ions and new mechanisms of fragmentation. The new methodology combines, by first time, high resolution time-of-flight mass spectrometry and powerful post-processing software. Native chlorophyllides and pheophorbides mainly exhibit product ions that involve the fragmentation of D ring, as well as additional exclusive product ions. The introduction of an oxygenated function at E ring enhances the progress of fragmentation reactions through the β-keto ester group, developing also exclusive product ions for 132-hydroxy derivatives and for 151-hydroxy-lactone ones. Consequently, while MS2-based reactions of phytylated chlorophyll derivatives point to fragmentations at the phytyl and propionic chains, dephytylated chlorophyll derivatives behave different as the absence of phytyl makes β-keto ester group and E ring more prone to fragmentation. Proposals of the key reaction mechanisms underlying the origin of new product ions have been made.
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