Association Between Components of Cognitive Reserve and Serum BDNF in Healthy Older Adults

Isolation and Identification of the High-Affinity DNA Aptamer Target to the Brain-Derived Neurotrophic Factor (BDNF)

Aptamers are functional oligonucleotide ligands used for the molecular recognition of various targets. The natural characteristics of aptamers make them an excellent alternative to antibodies in diagnostics, therapeutics, and biosensing. DNA aptamers are mainly single-stranded oligonucleotides (ssDNA) that possess a definite binding to targets. However, the application of aptamers to the fields of brain health and neurodegenerative diseases has been limited to date. Herein, a DNA aptamer against the brain-derived neurotrophic factor (BDNF) protein was obtained by in vitro selection. BDNF is a potential biomarker of brain health and neurodegenerative diseases and has functions in the synaptic plasticity and survival of neurons. We identified eight aptamers that have binding affinity for BDNF from a 50-nucleotide library. Among these aptamers, NV_B12 showed the highest sensitivity and selectivity for detecting BDNF. In an aptamer-linked immobilized sorbent assay (ALISA), the NV_B12 aptamer strongly bound to BDNF protein, in a dose-dependent manner. The dissociation constant (Kd) for NV_B12 was 0.5 nM (95% CI: 0.4-0.6 nM). These findings suggest that BDNF-specific aptamers could be used as an alternative to antibodies in diagnostic and detection assays for BDNF.

Long-term environmental enrichment is associated with better fornix microstructure in older adults

Background

Sustained environmental enrichment (EE) through a variety of leisure activities may decrease the risk of developing Alzheimer's disease. This cross-sectional cohort study investigated the association between long-term EE in young adulthood through middle life and microstructure of fiber tracts associated with the memory system in older adults.

Methods

N = 201 cognitively unimpaired participants (≥ 60 years of age) from the DZNE-Longitudinal Cognitive Impairment and Dementia Study (DELCODE) baseline cohort were included. Two groups of participants with higher (n = 104) or lower (n = 97) long-term EE were identified, using the self-reported frequency of diverse physical, intellectual, and social leisure activities between the ages 13 to 65. White matter (WM) microstructure was measured by fractional anisotropy (FA) and mean diffusivity (MD) in the fornix, uncinate fasciculus, and parahippocampal cingulum using diffusion tensor imaging. Long-term EE groups (lower/higher) were compared with adjustment for potential confounders, such as education, crystallized intelligence, and socio-economic status.

Results

Reported participation in higher long-term EE was associated with greater fornix microstructure, as indicated by higher FA (standardized β = 0.117, p = 0.033) and lower MD (β = -0.147, p = 0.015). Greater fornix microstructure was indirectly associated (FA: unstandardized B = 0.619, p = 0.038; MD: B = -0.035, p = 0.026) with better memory function through higher long-term EE. No significant effects were found for the other WM tracts.

Conclusion

Our findings suggest that sustained participation in a greater variety of leisure activities relates to preserved WM microstructure in the memory system in older adults. This could be facilitated by the multimodal stimulation associated with the engagement in a physically, intellectually, and socially enriched lifestyle. Longitudinal studies will be needed to support this assumption.

Effects of cognitive stimulation program on cognition and mood in older adults, stratified by cognitive levels: A randomized controlled trial

PURPOSE OF THE RESEARCH

Cognitive stimulation (CS) is defined as activities that involve cognitive processing, usually conducted in a social context and often in a group. This study aims to evaluate the effects of a personalized-adapted CS program in older adults on global cognition, neuropsychological constructs, activities of daily living (ADLs), and mood.

MATERIALS AND METHODS

The randomized controlled single-blind trial involving 337 participants (235 women and 102 men) ≥ 65 years of age in a Primary Care centre classified participants into 4 groups: 101 for the no deterioration (ND) group; 100 for the subjective cognitive impairment (SCI) group; 108 for the level deterioration (LD) group and 28 for the moderate deterioration group. The intervention consisted of a personalized CS adapted program for 10 weeks. Follow-up assessments were conducted post-intervention, and at 6 and 12 months. The primary outcome was global cognition measured by the Spanish version of the Mini-Mental State Examination. The secondary outcomes were measured by the Barthel Index, the Lawton and Brody Scale, the Goldberg Questionnaire (anxiety sub-scale) and the abbreviated Yesavage Geriatric Depression Scale.

RESULTS

The intervention showed a tendency of improvement on global cognition and different cognitive functions for groups with no deterioration or level deterioration. The group with moderate deterioration improved in anxiety.

CONCLUSIONS

The findings demonstrated benefits in global cognition, different cognitive functions, semantic fluency, IADLs and anxiety. The most benefits are given in the intermediate groups, SCI, and LD. Moreover, the intervention works by increasing the benefits in the different phases.

Cognitive stimulation and cognitive results in older adults: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

The lack of cognitive activity accelerates age cognitive decline. Cognitive stimulation (CS) tries to enhance cognitive functioning. The purpose of this systematic review and meta-analysis was to evaluate the effects of CS on cognitive outcomes (general cognitive functioning and specific cognitive domains) in older adults (aged 65 years or older, cognitively healthy participants, or with mild cognitive impairment, or dementia).

METHODS

PubMed, Scopus and Web of Science databases were examined from inception to October 2021. A total of 1,997 studies were identified in these databases, and. 33 studies were finally included in the systematic review and the meta-analysis. Raw means and standard deviations were used for continuous outcomes. Publication bias was examined by Egger's Regression Test for Funnel Plot Asymmetry and the quality assessment tools from the National Institutes of Health.

RESULTS

CS significantly improves general cognitive functioning (mean difference=MD = 1.536, 95%CI, 0.832 to 2.240), memory (MD = 0.365, 95%CI, 0.300 to 0.430), orientation (MD = 0.428, 95%CI, 0.306 to 0.550), praxis (MD = 0.278, 95%CI, 0.094 to 0.462) and calculation (MD = 0.228, 95%CI, 0.112 to 0.343).

CONCLUSION

CS seems to increase general cognitive functioning, memory, orientation, praxis, and calculation in older adults.

The association between global cognitive function and walking capacity in individuals with broad ranges of cognitive and physical function: Are there sex differences?

Introduction

Cognitive function is known to be associated with physical function, where greater walking capacity has been shown to have moderate to strong correlations with global cognitive function and other various domains of cognition in older adults with and without chronic conditions. Biological sex may moderate the relationship between cognitive and physical function, but whether sex differences exist in this association has not been examined in an aging population. The purpose of this study was to examine the associations between global cognitive function (Montreal Cognitive Assessment; MoCA), walking capacity (6-Minute Walk Test distance; 6 MWT) and sex in an aging population with broad ranges of cognitive and physical function.

Methods

Participants were assessed for global cognitive function (MoCA) and walking capacity (6 MWT). Multivariable regression analyses were performed to examine the interaction of sex in the association between MoCA and 6 MWT. First, we presented the unadjusted model (Model 1), then the model adjusted for age, history of stroke, and height (Model 2). To determine if there were sex-based differences in the association between global cognitive function and walking capacity, we included sex and an interaction term between sex*6 MWT distance in Models 3 and 4.

Results

Twenty-three females and 36 males were included in the multivariable regression analyses, respectively. Our sample represented broad ranges of cognitive and physical function levels, where MoCA scores ranged from 13 to 30, and 6 MWT distances from 203 to 750 m. 6 MWT distance was associated with MoCA in models unadjusted (R2 = 0.17; F(1,56) = 11.4; p < 0.01) and adjusted for age, stroke history, and height (R2 = 0.20; F(4,53) = 3.2; p = 0.02). No interaction with sex was found, but a main effect of sex was observed (R2 = 0.26; F(5,21) = 3.72; p = 0.03). When adjusting for age, height and history of stroke, males MoCA scores were 2.9 ± 1.3 less than the mean MoCA scores for females.

Discussion

Our findings confirm the positive relationship between cognitive and physical function in older adults. Notably, we also observed superior performance in global cognition among females that was consistent across a broad spectrum of walking capacity.

Musical Activity During Life Is Associated With Multi-Domain Cognitive and Brain Benefits in Older Adults

Regular musical activity as a complex multimodal lifestyle activity is proposed to be protective against age-related cognitive decline and Alzheimer’s disease. This cross-sectional study investigated the association and interplay between musical instrument playing during life, multi-domain cognitive abilities and brain morphology in older adults (OA) from the DZNE-Longitudinal Cognitive Impairment and Dementia Study (DELCODE) study. Participants reporting having played a musical instrument across three life periods (n = 70) were compared to controls without a history of musical instrument playing (n = 70), well-matched for reserve proxies of education, intelligence, socioeconomic status and physical activity. Participants with musical activity outperformed controls in global cognition, working memory, executive functions, language, and visuospatial abilities, with no effects seen for learning and memory. The musically active group had greater gray matter volume in the somatosensory area, but did not differ from controls in higher-order frontal, temporal, or hippocampal volumes. However, the association between gray matter volume in distributed frontal-to-temporal regions and cognitive abilities was enhanced in participants with musical activity compared to controls. We show that playing a musical instrument during life relates to better late-life cognitive abilities and greater brain capacities in OA. Musical activity may serve as a multimodal enrichment strategy that could help preserve cognitive and brain health in late life. Longitudinal and interventional studies are needed to support this notion.

Actigraphy-estimated physical activity is associated with functional and structural brain connectivity among older adults

Higher physical activity levels are associated with reduced cognitive decline among older adults; however, current understanding of underlying brain mechanisms is limited. This cross-sectional study investigated the relationship between actigraphy-estimated total volume of physical activity (TVPA) and magnetic resonance imaging (MRI) measures of white matter hyperintensities (WMH), and functional and structural brain connectivity, measured by resting-state functional MRI and diffusion tensor imaging. Study participants (N = 156, mean age = 71 years) included 136 with normal cognition and 20 with Mild Cognitive Impairment. Higher TVPA was associated with greater functional connectivity within the default-mode network and greater network modularity (a measure of network specialization), as well as with greater anisotropy and lower radial diffusion in white matter, suggesting better structural connectivity. These associations with functional and structural connectivity were independent of one another and independent of the level of vascular risk, APOE-ε4 status, cognitive reserve, and WMH volume, which were not associated with TVPA. Findings suggest that physical activity is beneficial for brain connectivity among older individuals with varying levels of risk for cognitive decline.

Age-Dependent Association Between Cognitive Reserve Proxy and Longitudinal White Matter Microstructure in Older Adults

Objective

This study examined the association of lifetime experiences, measured by a cognitive reserve (CR) composite score composed of years of education, literacy, and vocabulary measures, to level and rate of change in white matter microstructure, as assessed by diffusion tensor imaging (DTI) measures. We also examined whether the relationship between the proxy CR composite score and white matter microstructure was modified by participant age, APOE-ε4 genetic status, and level of vascular risk.

Methods

A sample of 192 non-demented (n = 166 cognitively normal, n = 26 mild cognitive impairment) older adults [mean age = 70.17 (SD = 8.5) years] from the BIOCARD study underwent longitudinal DTI (mean follow-up = 2.5 years, max = 4.7 years). White matter microstructure was quantified by fractional anisotropy (FA) and radial diffusivity (RD) values in global white matter tracts and medial temporal lobe (MTL) white matter tracts.

Results

Using longitudinal linear mixed effect models, we found that FA decreased over time and RD increased over time in both the global and MTL DTI composites, but the rate of change in these DTI measures was not related to level of CR. However, there were significant interactions between the CR composite score and age for global RD in the full sample, and for global FA, global RD, and MTL RD among those with normal cognition. These interactions indicated that among participants with a lower baseline age, higher CR composite scores were associated with higher FA and lower RD values, while among participants with higher age at baseline, higher CR composite scores were associated with lower FA and higher RD values. Furthermore, these relationships were not modified by APOE-ε4 genotype or level of vascular risk.

Conclusion

The association between level of CR and DTI measures differs by age, suggesting a possible neuroprotective effect of CR among late middle-aged adults that shifts to a compensatory effect among older adults.

Profiling the Research Landscape on Cognitive Aging: A Bibliometric Analysis and Network Visualization

Objectives

This study aimed to profile the cognitive aging research landscape from 1956 to 2021.

Methods

A total of 3,779 documents were retrieved from the Scopus database for the bibliometric analysis and network visualization. By comparing each keyword's overall connection strength (centrality), frequency (density), and average year of publication (novelty) to the calculated median values acquired from the overlay view of the VOSviewer map, the enhanced strategic diagrams (ESDs) were constructed.

Results

The findings showed an increasing trend in the number of publications. The United States leads the contributing countries in cognitive aging research. The scientific productivity pattern obeyed Lotka's law. The most productive researcher was Deary, I. J., with the highest number of publications. The collaborative index showed an increasing trend from 1980 onwards. Frontiers in Aging Neuroscience is the most prestigious journal in the field of cognitive aging research. In Bradford core journals zone 1, the top 10 core journals of cognitive aging research provided more than half of the total articles (697, or 55.36 percent).

Conclusions

For the next decades, the trending topics in cognitive aging research include neuropsychological assessment, functional connectivity, human immunodeficiency virus (HIV), decision-making, gender, compensation, default mode network, learning and memory, brain-derived neurotrophic factor (BDNF), obesity, D-galactose, epigenetics, frailty, mortality, mini-mental state examination (MMSE), anxiety, and gait speed.