Predictors and Implications of Accelerated Cognitive Aging

Tongue coating-dependent superior temporal sulcus remodeling in amnestic mild cognitive impairment

Tongue coating affects cognition, and cognitive decline at early stage also showed relations to functional and structural remodeling of superior temporal sulcus (STS) in amnestic mild cognitive impairment (aMCI). The potential correlation between disparate cognitive manifestations in aMCI patients with different tongue coatings, and corresponding mechanisms of STS remodeling remains uncharted. In this case-control study, aMCI patients were divided into thin coating (n = 18) and thick coating (n = 21) groups. All participants underwent neuropsychological evaluations and multimodal magnetic resonance imaging. Group comparisons were conducted in clinical assessments and neuroimaging measures of banks of the STS (bankssts). Generalized linear models were constructed to explore relationships between neuroimaging measures and cognition. aMCI patients in the thick coating group exhibited significantly poorer immediate and delayed recall and slower information processing speed (IPS) (P < 0.05), and decreased functional connectivity (FC) of bilateral bankssts with frontoparietal cortices (P < 0.05, AlphaSim corrected) compared to the thin coating group. It was found notable correlations between cognition encompassing recall and IPS, and FC of bilateral bankssts with frontoparietal cortices (P < 0.05, Bonferroni's correction), as well as interaction effects of group × regional homogeneity (ReHo) of right bankssts on the first immediate recall (P < 0.05, Bonferroni's correction). aMCI patients with thick coating exhibited poor cognitive performance, which might be attributed to decreased FC seeding from bankssts. Our findings strengthen the understanding of brain reorganization of STS via which tongue coating status impacts cognition in patients with aMCI.

The Association Between Cardiometabolic Risk and Cognitive Function Among Older Americans and Chinese

BACKGROUND

Cardiometabolic risk (CMR) is associated with cognitive health, but the association can be affected by broader social, economic, and medical contexts. The United States and China have very different developmental and epidemiological histories, and thus CMR among older people could be linked to cognitive function differently in the 2 countries.

METHODS

Cross-sectional and longitudinal ordinary least squares regression models were estimated for each country using nationally representative samples of populations over age 50: 7 430/4 474 Americans and 6 108/3 655 Chinese in the cross-sectional/longitudinal samples.

RESULTS

In the United States, higher CMR is associated with worse cognitive function (b = -0.08, p < .016). Longitudinally, CMR increase is associated with worse cognitive function at a marginally significant level (b = -0.10, p = .055). No relationship between CMR level or change and cognitive function is observed in China. Higher education levels are linked to better cognitive function and slower cognitive decline in both countries. Unlike older Americans, relative to those with very low education levels, among older Chinese with the highest education level, a higher CMR links to better cognitive function (b = 0.63, p = .013) and slower cognitive decline (b = 0.35, p = .062); Nevertheless, a rapid increase in CMR is additionally harmful (b = -0.54, p = .050) for cognitive function and may lead to faster cognitive decline (b = -0.35, p = .079).

CONCLUSIONS

The significant relationship between CMR and cognitive function in the United States suggests the importance of monitoring and controlling CMR factors at older ages. The insignificant relationship in China may be explained by the high CMR among those with high education levels, highlighting the need for improving cardiometabolic health through education and promoting healthy lifestyles.

Cognition and Cognitive Changes in a Low-Income Sub-Saharan African Aging Population

BACKGROUND

Cognition and its age-related changes remain vastly understudied in low-income countries (LICs), despite evidence suggesting that cognitive decline among aging low-income populations is a rapidly increasing disease burden often occurring at younger ages as compared to high-income countries (HICs).

OBJECTIVE

We examine patterns of cognition among men and women, 45 + years old, living in rural Malawi. We analyze how key socioeconomic characteristics predict levels of cognition and its changes as individuals get older.

METHODS

Utilizing the Mature Adults Cohort of the Malawi Longitudinal Study of Families and Health (MLSFH-MAC) collected during 2012-2017, we estimate standard regression models to analyze predictors of the age- and sex-specific levels and longitudinal changes in cognition. Cognition is assessed with a screening instrument that is adapted to this low-literacy context and measures different domains such as language, attention, or executive functioning.

RESULTS

Women have lower levels of cognition than men, a pattern in stark contrast to findings in HICs. Schooling and socioeconomic status increase the probability of having consistently high performance during the cognitive assessment. Cognitive decline accelerates with age and is detectable already at mid-adult ages (45-55 years). Despite lower levels of cognitive function observed among women, the pace of decline with age is similar for both genders.

CONCLUSION

Women are particularly affected by poor cognition in this context. The study emphasizes the importance of prioritizing cognitive health and research on cognition among older individuals in sub-Saharan Africa LICs, to which relatively little health care resources continue to be allocated.

A new cognitive clock matching phenotypic and epigenetic ages

Cognitive abilities decline with age, constituting a major manifestation of aging. The quantitative biomarkers of this process, as well as the correspondence to different biological clocks, remain largely an open problem. In this paper we employ the following cognitive tests: 1. differentiation of shades (campimetry); 2. evaluation of the arithmetic correctness and 3. detection of reversed letters and identify the most significant age-related cognitive indices. Based on their subsets we construct a machine learning-based Cognitive Clock that predicts chronological age with a mean absolute error of 8.62 years. Remarkably, epigenetic and phenotypic ages are predicted by Cognitive Clock with an even better accuracy. We also demonstrate the presence of correlations between cognitive, phenotypic and epigenetic age accelerations that suggests a deep connection between cognitive performance and aging status of an individual.

Race Inequity in School Attendance Across the Jim Crow South and Its Implications for Black-White Disparities in Trajectories of Cognitive Function Among Older Adults

OBJECTIVES

Although education is a key determinant of cognitive function, its role in determining Black-White disparities in cognitive function is unclear. This may be due, in part, to data limitations that have made it difficult to account for systemic educational inequities in the Jim Crow South experienced by older cohorts, including differences in the number of days Black students attended school compared to their White counterparts or Black peers in better-funded southern states. We determine if accounting for differential rates of school attendance across race, years, and states in the Jim Crow South better illuminates Black-White disparities in trajectories of cognitive function.

METHODS

We linked historical state-level data on school attendance from the 1919/1920 to 1953/1954 Biennial Surveys of Education to the Health and Retirement Study, a nationally representative, longitudinal study of U.S. adults older than age 50. We restricted our sample to Black and White older adults who attended school in the Jim Crow South and began primary school in/after 1919/1920 and completed primary/secondary school by 1953/1954 (n = 4,343). We used linear mixed models to estimate trajectories of total cognitive function, episodic memory, and working memory.

RESULTS

Self-reported years of schooling explained 28%-33% of the Black-White disparity in level of cognitive function, episodic memory, and working memory. Duration of school, a measure that accounted for differential rates of school attendance, explained 41%-55% of the Black-White disparity in these outcomes.

DISCUSSION

Our study highlights the importance of using a more refined measure of schooling for understanding the education-cognitive health relationship.

Trends in Dementia Prevalence, Incidence, and Mortality in the United States (2000-2016)

Objectives: The prevalence of dementia has declined in the United States; how this parallels to changes in incidence and mortality, and how improvements in educational attainment may have influences these trends, is not known. Methods: Using the Health and Retirement Study (2000-2016), we estimated logistic regression models to examine trends in dementia prevalence and incidence, and mortality for those with and without dementia. Results: The relative decline was about 2.4% per year for dementia prevalence and 1.9% for dementia incidence. Mortality declined similarly for those with and without dementia. Improved educational attainment accounted for decline in incidence, some of the decline in prevalence, and had a negligible role in mortality. Discussion: The declines in dementia incidence provide evidence that dementia prevalence should continue to decline in the near future. These declines are most likely largely driven by continued improvements in older adult education.

Making the Best Out of IT: Design and Development of Exergames for Older Adults With Mild Neurocognitive Disorder - A Methodological Paper

Background: Utilizing information technology (IT) systems, for example in form of computerized cognitive screening or exergame-based (also called active videogames) training, has gained growing interest for supporting healthy aging and to detect, prevent and treat neurocognitive disorders (NCD). To ameliorate the effectiveness of exergaming, the neurobiological mechanisms as well as the most effective components for exergame-based training remain to be established. At the same time, it is important to account for the end-users' capabilities, preferences, and therapeutic needs during the design and development process to foster the usability and acceptance of the resulting program in clinical practice. This will positively influence adherence to the resulting exergame-based training program, which, in turn, favors more distinct training-related neurobiological effects. Objectives and Methods: This methodological paper describes the design and development process of novel exergame-based training concepts guided by a recently proposed methodological framework: The 'Multidisciplinary Iterative Design of Exergames (MIDE): A Framework for Supporting the Design, Development, and Evaluation of Exergames for Health' (Li et al., 2020). Case Study: A step-by-step application of the MIDE-framework as a specific guidance in an ongoing project aiming to design, develop, and evaluate an exergame-based training concept with the aim to halt and/or reduce cognitive decline and improve quality of life in older adults with mild neurocognitive disorder (mNCD) is illustrated. Discussion and Conclusion: The development of novel exergame-based training concepts is greatly facilitated when it is based on a theoretical framework (e.g., the MIDE-framework). Applying this framework resulted in a structured, iterative, and evidence-based approach that led to the identification of multiple key requirements for the exergame design as well as the training components that otherwise may have been overlooked or neglected. This is expected to foster the usability and acceptance of the resulting exergame intervention in "real life" settings. Therefore, it is strongly recommended to implement a theoretical framework (e.g., the MIDE-framework) for future research projects in line with well-known checklists to improve completeness of reporting and replicability when serious games for motor-cognitive rehabilitation purposes are to be developed.

Cognition in context: Pathways and compound risk in a sample of US non-Hispanic whites

The population of individuals with cognitive impairment and dementia is growing rapidly, necessitating etiological investigation. It is clear that individual differences in cognition later in life have both genetic and multi-level environmental correlates. Despite significant recent progress in cellular and molecular research, the exact mechanisms linking genes, brains, and cognition remain elusive. In relation to cognition, it is unlikely that genetic and environmental risk factors function in a vacuum, but rather interact and cluster together. The purpose of the present study was to examine whether aspects of individual socioeconomic status (SES) explain the cognitive genotype-phenotype association, and whether neighborhood SES modifies the effects of genes and individual SES on cognitive ability. Using data from non-Hispanic White participants in the 2016 wave of the Health and Retirement Study, a national sample of United States adults, we examined links between a polygenic score for general cognition and performance-based cognitive functioning. In a series of weighted linear regressions and formal tests of mediation, we observed a significant genotype-phenotype association that was partially attenuated after including individual education to the baseline model, although little reductions were observed for household wealth or census tract-level percent poverty. These findings suggest that genetic risk for poor cognition is partially explained by education, and this pathway is not modified by poverty-level of the neighborhood.

Aging biomarkers and the brain

Quantifying biological aging is critical for understanding why aging is the primary driver of morbidity and mortality and for assessing novel therapies to counter pathological aging. In the past decade, many biomarkers relevant to brain aging have been developed using various data types and modeling techniques. Aging involves numerous interconnected processes, and thus many complementary biomarkers are needed, each capturing a different slice of aging biology. Here we present a hierarchical framework highlighting how these biomarkers are related to each other and the underlying biological processes. We review those measures most studied in the context of brain aging: epigenetic clocks, proteomic clocks, and neuroimaging age predictors. Many studies have linked these biomarkers to cognition, mental health, brain structure, and pathology during aging. We also delve into the challenges and complexities in interpreting these biomarkers and suggest areas for further innovation. Ultimately, a robust mechanistic understanding of these biomarkers will be needed to effectively intervene in the aging process to prevent and treat age-related disease.

Can Reactivity of Heart Rate Variability Be a Potential Biomarker and Monitoring Tool to Promote Healthy Aging? A Systematic Review With Meta-Analyses

Background: Monitoring phasic responses of heart rate variability (HRV) in terms of HRV reactivity [i. e., the absolute change from resting state to on-task (i.e., absolute values of HRV measured during exercise)] might provide useful insights into the individual psychophysiological responses of healthy middle-aged to older adults (HOA) to cognitive and physical exercises. Objectives: To summarize the evidence of phasic HRV responses to cognitive and physical exercises, and to evaluate key moderating factors influencing these responses. Methods: A systematic review with meta-analyses was performed. Publications up to May 2020 of the databases Medline (EBSCO), Embase, Cochrane Library, CINAHL, Psycinfo, Web of Science, Scopus, and Pedro were considered. Controlled clinical trials and observational studies measuring phasic HRV responses to cognitive and/or physical exercises in HOA (≥50 years) were included. Results: The initial search identified 6,828 articles, of which 43 were included into the systematic review. Compared to resting state, vagally-mediated HRV indices were significantly reduced during all types of exercises [Hedge's g = -0.608, 95 % CI (-0.999 to -0.218), p = 0.002] indicating a significant parasympathetic withdrawal compared to rest. The key moderating variables of these responses identified included exercise intensity for physical exercises, and participant characteristics (i.e., level of cognitive functioning, physical fitness), task demands (i.e., task complexity and modality) and the individual responses to these cognitive challenges for cognitive exercises. In particular, higher task demands (task complexity and physical exercise intensity) were related to larger HRV reactivities. Better physical fitness and cognition were associated with lower HRV reactivities. Additionally, HRV reactivity appeared to be sensitive to training-induced cognitive and neural changes. Conclusion: HRV reactivity seems to be a promising biomarker for monitoring internal training load and evaluating neurobiological effects of training interventions. Further research is warranted to evaluate the potential of HRV reactivity as a monitoring parameter to guide cognitive-motor training interventions and/or as a biomarker for cognitive impairment. This may facilitate the early detection of cognitive impairment as well as allow individualized training adaptations that, in turn, support the healthy aging process by optimizing individual exercise dose and progression of cognitive-motor training.

Mitochondrial Functions, Cognition, and the Evolution of Intelligence: Reply to Commentaries and Moving Forward

In response to commentaries, I address questions regarding the proposal that general intelligence (g) is a manifestation of the functioning of intramodular and intermodular brain networks undergirded by the efficiency of mitochondrial functioning (Geary 2018). The core issues include the relative contribution of mitochondrial functioning to individual differences in g; studies that can be used to test associated hypotheses; and, the adaptive function of intelligence from an evolutionary perspective. I attempt to address these and related issues, as well as note areas in which other issues remain to be addressed.

Early detection of cognitive disturbances in mild cognitive impairment: a systematic review of observational studies

Mild cognitive impairment (MCI) is an intermediate state between normal cognition and early dementia and is not considered as a typical outcome of brain aging. It has been estimated that 10% to 20% of individuals above 65 years of age will be diagnosed as having MCI. The increased rate of dementia and the importance of early detection of its forerunners have encouraged researchers to focus on detecting MCI and modifiable risk factors with the hope of developing better ways of managing dementia and its consequences. The main aim of this study was to systematically review the related literature concerning the cognitive changes in the spectrum of cognitive aging to cognitive impairment. Articles included in this review were identified through searching the databases of PubMed, Psych Info, Embase, ProQuest, and Scopus. Many domains like verbal memory, language, executive function, visual memory, attentional skills, and working memory showed acceptable predictive power. Testing subdomains such as executive function, speed of processing, working memory and semantic language are critical and others may indicate some suggestions for further clinical deteriorations in normal individuals. Although various cognitive instruments have been used for evaluation of impaired cognitive domains, it remains challenging to select the most appropriate ones having high-level accuracy and their related cognitive subdomains. It also revealed that none of the identified cognitive domains solely fulfilled the criteria for MCI screening; in clinical settings, multiple neuropsychological batteries may be used for one single cognitive domain, while longitudinal studies prefer the use of at least two cognitive measures for each domain to improve accuracy and research settings might focus on only a single neuropsychological test. However, along with episodic memory, testing for amnestic MCI, executive function could increase the chance of early detection of MCI. Executive control has been found to deteriorate the earliest in MCI patients.

The Alzheimer's Disease Exposome

INTRODUCTION

Environmental factors are poorly understood in the etiology of Alzheimer's disease (AD) and related dementias. The importance of environmental factors in gene environment interactions (GxE) is suggested by wide individual differences in cognitive loss, even for carriers of AD-risk genetic variants.

RESULTS AND DISCUSSION

We propose the "AD exposome" to comprehensively assess the modifiable environmental factors relevant to genetic underpinnings of cognitive aging and AD. Analysis of endogenous and exogenous environmental factors requires multi-generational consideration of these interactions over age and time (GxExT). New computational approaches to the multi-level complexities may identify accessible interventions for individual brain aging. International collaborations on diverse populations are needed to identify the most relevant exposures over the life course for GxE interactions.