Education and cognitive reserve in old age

Cross-sectional and longitudinal associations between late-life depressive symptoms and cognitive deficits: 20-year follow-up of the Kuakini Honolulu-Asia aging study

OBJECTIVE

To examine depressed affect, somatic complaints, and positive affect as longitudinal predictors of fluid, crystallized and global cognitive performance in the Kuakini Honolulu-Asia Aging Study (HAAS), a large prospective cohort study of Japanese-American men.

METHODS

We assessed 3,088 dementia-free Kuakini-HAAS participants aged 71-93 (77.1 ± 4.2) years at baseline (1991-1993). Depressive symptoms were evaluated by the Center for Epidemiologic Studies Depression (CES-D) Scale. Baseline CES-D depression subscales (depressed and positive affects; somatic complaints) were computed. The Cognitive Abilities Screening Instrument (CASI) measured cognitive performance on a 100-point scale; fluid and crystallized cognitive abilities were derived from CASI factor analysis. Cognition was also evaluated at 4 follow-up examinations over a 20-year period. Multiple regression assessed baseline CES-D subscales as predictors of cognitive change. The baseline covariates analyzed were CASI, age, education, prevalent stroke, APOE ε4 presence, and the longevity-associated FOXO3 genotype.

RESULTS

Cross-sectionally, baseline CES-D subscales were related to cognitive measures; e.g., higher depressed affect was associated with lower crystallized ability (β = -0.058, p ≤ 0.01), and somatic complaints were linked to poorer fluid ability (β = -0.045, p ≤ 0.05) and to worse global cognitive function as measured by total CASI score (β = -0.038, p ≤ 0.05). However, depression subscales did not significantly or consistently predict fluid ability, crystallized ability, or global cognitive performance over time.

CONCLUSION

Psychological and physical well-being were associated with contemporaneous but not subsequent cognitive functioning. Assessment of depressive symptoms may identify individuals who are likely to benefit from interventions to improve mood and somatic health and thereby maintain or enhance cognition.

Social cohesion as a modifier of joint air pollution exposure and incident dementia

Social cohesion can reduce stress, increase social interaction, and improve cognitive reserve. These social mechanisms may modify the effects of air pollution on dementia risk. This cohort study examines the potential moderating effect of social cohesion on associations between joint air pollution exposure and incident dementia leveraging data from 5112 community-dwelling adults ≥65 years of age enrolled in the National Health and Aging Trends Study (NHATS). Study participants were enrolled in 2011 and followed through 2018. We assigned 2010 residential census tract-level exposures to five air pollutants, particulate matter (PM) ≤ 10 μm in diameter, PM ≤ 2.5 μm in diameter, carbon monoxide, nitric oxide, and nitrogen dioxide, using the US Environmental Protection Agency's Community Multiscale Air Quality Modeling System. Dementia status was determined based on self- or proxy-reported dementia diagnosis or "probable dementia" according to NHATS cognitive screening tools. Participants' self-rated neighborhood social cohesion was evaluated based on three questions: neighbors knowing each other, being helpful, and being trustworthy. Social cohesion was dichotomized at the median into high vs low social cohesion. Associations between air pollutants and incident dementia were assessed using quantile g-computation Cox proportional hazard models and stratified by high vs low social cohesion, adjusting for age, sex, education, partner status, urbanicity, annual income, race and ethnicity, years lived at current residence, neighborhood disadvantage index, and tract segregation. High social cohesion (HR = 1.20, 95 % CI = 0.98, 1.47) and air pollution (HR = 1.08, 95 % CI = 0.92, 1.28) were not associated with incident dementia alone. However, when stratified, greater joint air pollution exposure increased dementia risk among participants at low (HR = 1.34, 95 % CI = 1.04, 1.72), but not high (HR = 1.00, 95 % CI = 0.93, 1.06) social cohesion. Air pollution was a risk factor for dementia only when reported social cohesion was low, suggesting that social interaction may play a protective role, mitigating dementia risk via air pollution exposure.

Socio-cognitive mindfulness predicts memory complaint and cognitive performance of older adults with different years of education

BACKGROUND

Even though the effect of education on cognitive performance has been widely reported, the relationship between socio-cognitive mindfulness, cognitive performance, and memory complaint among the elderly with heterogeneous educational levels has not yet been investigated.

AIM

This study aimed to analyze the potential relationship between cognitive performance, memory complaint, and socio-cognitive mindfulness in a sample of healthy older adults with different years of education.

METHODS

In this quantitative, cross-sectional, observational, and analytical study, participants (n = 68) were assessed with a sociodemographic questionnaire, cognitive performance test (ACE-III), levels of socio-cognitive mindfulness (LSM-21), and memory complaint (Memory Complaint Scale). Descriptive statistics, as well as Pearson's correlation, and linear regression analysis were performed, and significance was assumed if p < .05.

RESULTS

Years of education correlated with cognitive performance and socio-cognitive mindfulness, but not with memory complaint. Socio-cognitive mindfulness had a positive correlation with cognitive performance and a negative correlation with memory complaint. Also, socio-cognitive mindfulness predicted cognitive performance and memory complaint both in bivariate analysis and when controlling for years of education.

CONCLUSION

Our findings suggested that older adults with higher levels of socio-cognitive mindfulness showed better cognitive performance and less memory complaint.

Cognitive reserve proxies are associated with age-related cognitive decline - Not age-related gait speed decline

Cognition and gait share brain substrates in aging and dementia. Cognitive reserve (CR) allows individuals to cope with brain pathology and delay cognitive impairment and dementia. Yet, evidence for that CR is associated with age-related cognitive decline is mixed, and evidence for that CR is associated with age-related gait decline is limited. In 1,079 older (M Age = 75.4 years; 56.0% women) LonGenity study participants without dementia at baseline and up to 12 years of annual follow-up (M follow-up = 3.9 years, SD = 2.5 years), high CR inferred from cognitive (education years), physical (number of blocks walked per day; weekly physical activity days), and social (volunteering/working; living with someone) proxies were associated with slower rates of age-related decline in global cognition - not gait speed decline. Thus, cognitive, physical, and social CR proxies are associated with cognitive decline in older adults without dementia. The multifactorial etiology and earlier decline in gait than cognition may render it less modifiable by CR proxies later in life.

Cellular communities reveal trajectories of brain ageing and Alzheimer's disease

Alzheimer's disease (AD) has recently been associated with diverse cell states1-11, yet when and how these states affect the onset of AD remains unclear. Here we used a data-driven approach to reconstruct the dynamics of the brain's cellular environment and identified a trajectory leading to AD that is distinct from other ageing-related effects. First, we built a comprehensive cell atlas of the aged prefrontal cortex from 1.65 million single-nucleus RNA-sequencing profiles sampled from 437 older individuals, and identified specific glial and neuronal subpopulations associated with AD-related traits. Causal modelling then prioritized two distinct lipid-associated microglial subpopulations-one drives amyloid-β proteinopathy while the other mediates the effect of amyloid-β on tau proteinopathy-as well as an astrocyte subpopulation that mediates the effect of tau on cognitive decline. To model the dynamics of cellular environments, we devised the BEYOND methodology, which identified two distinct trajectories of brain ageing, each defined by coordinated progressive changes in certain cellular communities that lead to (1) AD dementia or (2) alternative brain ageing. Thus, we provide a cellular foundation for a new perspective on AD pathophysiology that informs personalized therapeutic development, targeting different cellular communities for individuals on the path to AD or to alternative brain ageing.

Age-related neural changes underlying long-term recognition of musical sequences

Aging is often associated with decline in brain processing power and neural predictive capabilities. To challenge this notion, we used magnetoencephalography (MEG) and magnetic resonance imaging (MRI) to record the whole-brain activity of 39 older adults (over 60 years old) and 37 young adults (aged 18-25 years) during recognition of previously memorised and varied musical sequences. Results reveal that when recognising memorised sequences, the brain of older compared to young adults reshapes its functional organisation. In fact, it shows increased early activity in sensory regions such as the left auditory cortex (100 ms and 250 ms after each note), and only moderate decreased activity (350 ms) in medial temporal lobe and prefrontal regions. When processing the varied sequences, older adults show a marked reduction of the fast-scale functionality (250 ms after each note) of higher-order brain regions including hippocampus, ventromedial prefrontal and inferior temporal cortices, while no differences are observed in the auditory cortex. Accordingly, young outperform older adults in the recognition of novel sequences, while no behavioural differences are observed with regards to memorised ones. Our findings show age-related neural changes in predictive and memory processes, integrating existing theories on compensatory neural mechanisms in non-pathological aging.

Subjective Cognitive Impairment and Physical Activity: Investigating Risk Factors and Correlations among Older Adults in Spain

Subjective cognitive impairment in older persons has a substantial influence on their quality of life and can progress to serious illnesses such as dementia. Physical activity level can help prevent cognitive decline and improve cognitive performance. The aim of this study was to investigate the association between frequency of physical activity and subjective cognitive impairment in Spanish adults aged 65 and over, and to identify different risk factors. Using data from the EHSS20 survey, the study focused on 7082 participants who provided information on cognitive impairment and physical activity. Key predictor variables included age, gender, BMI, marital status, and education level. A significant relationship was found between BMI category and gender, with 66.5% of the population being overweight or obese. Men were more likely to be overweight than women. Socio-demographic factors such as educational level, marital status, and physical activity frequency showed dependent associations with sex. Women had a higher prevalence of subjective cognitive impairment than men. A strong association was found between frequency of physical activity and subjective cognitive impairment, with inactive older people having the highest prevalence of subjective cognitive impairment. Older women who engage in little physical exercise and have less education are at risk for subjective cognitive impairment. Furthermore, for both men and women, being overweight was associated with a more reduced risk than obesity. Significant relationships were also discovered between subjective cognitive impairment, frequency of physical exercise, gender, BMI, and degree of education. In conclusion, older, sedentary women with high BMI and less education are more likely to experience subjective cognitive impairment.

Development and Validity of Norms for Cognitive Dispersion on the Uniform Data Set 3.0 Neuropsychological Battery

OBJECTIVE

Cognitive dispersion indexes intraindividual variability in performance across a battery of neuropsychological tests. Measures of dispersion show promise as markers of cognitive dyscontrol and everyday functioning difficulties; however, they have limited practical applicability due to a lack of normative data. This study aimed to develop and evaluate normed scores for cognitive dispersion among older adults.

METHOD

We analyzed data from 4,283 cognitively normal participants aged ≥50 years from the Uniform Data Set (UDS) 3.0. We describe methods for calculating intraindividual standard deviation (ISD) and coefficient of variation (CoV), as well as associated unadjusted scaled scores and demographically adjusted z-scores. We also examined the ability of ISD and CoV scores to differentiate between cognitively normal individuals (n = 4,283) and those with cognitive impairment due to Lewy body disease (n = 282).

RESULTS

We generated normative tables to map raw ISD and CoV scores onto a normal distribution of scaled scores. Cognitive dispersion indices were associated with age, education, and race/ethnicity but not sex. Regression equations were used to develop a freely accessible Excel calculator for deriving demographically adjusted normed scores for ISD and CoV. All measures of dispersion demonstrated excellent diagnostic utility when evaluated by the area under the curve produced from receiver operating characteristic curves.

CONCLUSIONS

Results of this study provide evidence for the clinical utility of sample-based and demographically adjusted normative standards for cognitive dispersion on the UDS 3.0. These standards can be used to guide interpretation of intraindividual variability among older adults in clinical and research settings.

Parental History of Memory Impairment and β-Amyloid in Cognitively Unimpaired Older Adults

Importance

Studies have suggested that maternal history of late-onset Alzheimer disease, but not paternal, predisposes individuals to higher brain β-amyloid (Aβ) burden, reduced brain metabolism, and lower gray matter volumes.

Objective

To characterize maternal vs paternal history of memory impairment in terms of brain Aβ-positron emission tomography (Aβ-PET) and baseline cognition among a large sample of cognitively unimpaired older adults.

Design, Setting, and Participants

This cross-sectional study leveraged data from 4413 individuals who were screened for the Anti-Amyloid Treatment in Asymptomatic Alzheimer (A4) study, a randomized clinical trial conducted across 67 sites in the US, Australia, Canada, and Japan aimed at Alzheimer disease prevention. Data were collected between April 2014 and December 2017 and analyzed from December 2022 to June 2023. Participants were cognitively unimpaired adults (Clinical Dementia Rating = 0 and/or Mini-Mental State Examination score ≥25) between the ages of 65 and 85 years who underwent PET imaging to assess cortical Aβ levels for trial eligibility. A total of 4492 participants were screened, and 79 missing data were excluded.

Main Outcomes and Measures

Demographic characteristics (eg, age, sex, education), apolipoprotein E genotyping, participant-reported parental history of memory impairment and parental age at symptom onset were collected as variables. Parental history was assessed in terms of continuous neocortical 18F-florbetapir Aβ-PET and the Preclinical Alzheimer Cognitive Composite.

Results

Of 4413 individuals (mean [SD] age, 71.27 [4.66] years, 2617 women [59.3%]), mean Aβ-PET was elevated in individuals with history of memory impairment in both parents (n = 455; mean [SD] standardized uptake value ratio [SUVR] = 1.12 [0.19]; Wilcoxon P = 1.1 × 10-5) and in those with only maternal history (n = 1772; mean [SD] SUVR = 1.10 [0.19]; Wilcoxon P = 2.70 × 10-5) compared with those with only paternal history (n = 632; mean [SD] SUVR = 1.08 [0.18]; Wilcoxon P = 1.1 × 10-5) or no family history (n = 1554; mean [SD] SUVR = 1.08 [0.19]; Wilcoxon P = 1.1 × 10-5). Paternal history of early-onset memory impairment (age <65 years) but not late-onset (age ≥65 years) was associated with elevated participant Aβ-PET (mean [SD] SUVR = 1.19 [0.21]; P = 3.00 × 10-6) in comparison with no paternal history (mean [SD] SUVR = 1.09 [0.19]) whereas maternal history was associated with elevated Aβ in both early-onset and late-onset groups. There was no association with cognition.

Conclusions and Relevance

In this study, maternal history (at any age) and paternal history of early-onset memory impairment were associated with Aβ burden among asymptomatic older individuals. Sex-specific parental history may help inform clinicians on likelihood of Aβ burden in offspring and help identify high-risk individuals at the earliest stages of disease for prevention.

Sex and gender differences in cognitive resilience to aging and Alzheimer's disease

Sex and gender-biological and social constructs-significantly impact the prevalence of protective and risk factors, influencing the burden of Alzheimer's disease (AD; amyloid beta and tau) and other pathologies (e.g., cerebrovascular disease) which ultimately shape cognitive trajectories. Understanding the interplay of these factors is central to understanding resilience and resistance mechanisms explaining maintained cognitive function and reduced pathology accumulation in aging and AD. In this narrative review, the ADDRESS! Special Interest Group (Alzheimer's Association) adopted a multidisciplinary approach to provide the foundations and recommendations for future research into sex- and gender-specific drivers of resilience, including a sex/gender-oriented review of risk factors, genetics, AD and non-AD pathologies, brain structure and function, and animal research. We urge the field to adopt a sex/gender-aware approach to resilience to advance our understanding of the intricate interplay of biological and social determinants and consider sex/gender-specific resilience throughout disease stages. HIGHLIGHTS: Sex differences in resilience to cognitive decline vary by age and cognitive status. Initial evidence supports sex-specific distinctions in brain pathology. Findings suggest sex differences in the impact of pathology on cognition. There is a sex-specific change in resilience in the transition to clinical stages. Gender and sex factors warrant study: modifiable, immune, inflammatory, and vascular.

Navigating Prevention: A Systematic Review of Strategies for Alzheimer's Disease in High-Risk and Affected Individuals

Alzheimer's disease (AD) remains a widespread cause of dementia globally, and its prevalence is increasing due to the aging population. Two key pathologies typically identify this neurodegenerative disease process: the accumulation of amyloid plaques and the formation of neurofibrillary tangles containing hyperphosphorylated tau. Diagnosis relies on the patient's clinical presentation meeting specific criteria, along with the use of fluid and imaging biomarkers. The current treatment focuses on addressing symptoms, with ongoing trials aiming to decrease the production and overall impact of brain pathology. Here, we explore various methods to minimize the risks of AD in patients and individuals at high risk of developing it. To address this, we carefully selected 10 articles that discuss various prevention methods used today to promote brain health, including diets that are believed to have neuroprotective properties. The study findings emphasize the importance of further strengthening the evidence and conducting larger randomized controlled trials to gain a better understanding of the potential benefits for individuals at high risk of developing AD, as well as those already diagnosed with it.

The impact of education and occupation on cognitive impairment: a cross-sectional study in China

Background and objectives

Education, occupation, and cognitive activity are key indicators of cognitive reserve and are thought to influence cognitive impairment. However, the individual and combined impacts of these factors are not fully understood. This study aims to investigate the roles of education and occupation in cognitive impairment while controlling for brain reserve and cognitive activity.

Methods

This cross-sectional study involved 369 participants aged 50 years or older from urban outpatient clinics in Jilin Province, China. Cognitive impairment was assessed using neuropsychological scales and brain imaging. Cognitive activity was evaluated with the Cognitive Reserve Scale (CRS). Covariance analysis and logistic regression models were used to analyze the associations, adjusting for age, sex, education, and occupation.

Results

Higher education was significantly associated with a lower risk of cognitive impairment (p < 0.001), regardless of occupation. In contrast, occupational complexity and cognitive activity did not show a significant relationship with cognitive impairment (p > 0.05).

Conclusion

Education, rather than occupation or cognitive activities, is a significant predictor of cognitive impairment, highlighting the importance of educational attainment in cognitive health.

Educational Attainment Moderates Task-State Control Network Connectivity Relations to Response Conflict Among Healthy Older Adults

OBJECTIVES

Older adult executive function varies widely due to brain and cognitive aging. Variance in older adult executive function is linked to increased response conflict from cognitive and brain aging. Cognitive reserve (CR) is a theoretical protective mechanism that lessens brain aging's impact on cognition and is associated with greater educational attainment. Recent work in rest-state functional magnetic resonance imaging (fMRI) suggests CR proxies moderate the relationship between functional connectivity (FC) and cognitive performance. Brain network FC in "control networks," including the salience (SN), dorsal attention and frontoparietal networks, are associated with cognitive processes in older adults. CR is hypothesized to maintain cognitive processing in part through changes in how brain networks respond to cognitive demands. However, it is unclear how CR proxies like educational attainment are related to control network FC during performance when cognitive demands are increased relative to rest. Because CR is expressed more in those with higher education, we hypothesized stronger control network FC would relate to better performance, where this relationship would be strongest among the most educated.

METHODS

We collected flanker task data during fMRI to assess the impact of a CR proxy (i.e., educational attainment) on response conflict among older adult subjects (n = 42, age = 65-80).

RESULTS

Linear mixed-effects models showed more educated older adults with greater SN-FC had a smaller flanker effect (i.e., less influence of distractors; p < .001) during task performance.

DISCUSSION

For the first time, we show that educational attainment moderates the relationship between task-state SN-FC and executive function among older adults.

Cognitively high-performing oldest old individuals are physically active and have strong motor skills-A study of the Danish 1905 and 1915 birth cohorts

Preserving cognitive function with age or super-aging greatly contributes to successful aging. Super-aging nonagenarians born in Denmark in either year 1905 or 1915 were classified as Cognitively High-Performing Oldest Old individuals with a five item cognitive composite score, equivalent to or better than mean middle-aged subjects. Cognitively high-performers were more physically active and had a better physical performance on e.g., Activity of Daily Living (p-value < 0.01), gait speed (p-value < 0.01) and grip strength (p-value < 0.05) compared with age-matched peers. Cognitive high-performing was also linked to lower depression symptomatology. When comparing super-agers with semi super-agers classified by Mini Mental State Examination > 27, super-agers were still more physically active and had a better physical performance (p-value < 0.05). Results suggests that physical activity is a lifestyle factor strongly associated with both semi and full cognitive super-aging.

Age-related differences in network controllability are mitigated by redundancy in large-scale brain networks

The aging brain undergoes major changes in its topology. The mechanisms by which the brain mitigates age-associated changes in topology to maintain robust control of brain networks are unknown. Here we use diffusion MRI data from cognitively intact participants (n = 480, ages 40-90) to study age-associated differences in the average controllability of structural brain networks, topological features that could mitigate these differences, and the overall effect on cognitive function. We find age-associated declines in average controllability in control hubs and large-scale networks, particularly within the frontoparietal control and default mode networks. Further, we find that redundancy, a hypothesized mechanism of reserve, quantified via the assessment of multi-step paths within networks, mitigates the effects of topological differences on average network controllability. Lastly, we discover that average network controllability, redundancy, and grey matter volume, each uniquely contribute to predictive models of cognitive function. In sum, our results highlight the importance of redundancy for robust control of brain networks and in cognitive function in healthy-aging.

2024 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease (AD), including prevalence and incidence, mortality and morbidity, use and costs of care and the ramifications of AD for family caregivers, the dementia workforce and society. The Special Report discusses the larger health care system for older adults with cognitive issues, focusing on the role of caregivers and non-physician health care professionals. An estimated 6.9 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060, barring the development of medical breakthroughs to prevent or cure AD. Official AD death certificates recorded 119,399 deaths from AD in 2021. In 2020 and 2021, when COVID-19 entered the ranks of the top ten causes of death, Alzheimer's was the seventh-leading cause of death in the United States. Official counts for more recent years are still being compiled. Alzheimer's remains the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2021, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 140%. More than 11 million family members and other unpaid caregivers provided an estimated 18.4 billion hours of care to people with Alzheimer's or other dementias in 2023. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $346.6 billion in 2023. Its costs, however, extend to unpaid caregivers' increased risk for emotional distress and negative mental and physical health outcomes. Members of the paid health care and broader community-based workforce are involved in diagnosing, treating and caring for people with dementia. However, the United States faces growing shortages across different segments of the dementia care workforce due to a combination of factors, including the absolute increase in the number of people living with dementia. Therefore, targeted programs and care delivery models will be needed to attract, better train and effectively deploy health care and community-based workers to provide dementia care. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are almost three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 22 times as great. Total payments in 2024 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $360 billion. The Special Report investigates how caregivers of older adults with cognitive issues interact with the health care system and examines the role non-physician health care professionals play in facilitating clinical care and access to community-based services and supports. It includes surveys of caregivers and health care workers, focusing on their experiences, challenges, awareness and perceptions of dementia care navigation.

Cognitive resilience/reserve: Myth or reality? A review of definitions and measurement methods

INTRODUCTION

This review examines the concept of cognitive reserve (CR) in relation to brain aging, particularly in the context of dementia and its early stages. CR refers to an individual's ability to maintain or regain cognitive function despite brain aging, damage, or disease. Various factors, including education, occupation complexity, leisure activities, and genetics are believed to influence CR.

METHODS

We revised the literature in the context of CR. A total of 842 articles were identified, then we rigorously assessed the relevance of articles based on titles and abstracts, employing a systematic approach to eliminate studies that did not align with our research objectives.

RESULTS

We evaluate-also in a critical way-the methods commonly used to define and measure CR, including sociobehavioral proxies, neuroimaging, and electrophysiological and genetic measures. The challenges and limitations of these measures are discussed, emphasizing the need for more targeted research to improve the understanding, definition, and measurement of CR.

CONCLUSIONS

The review underscores the significance of comprehending CR in the context of both normal and pathological brain aging and emphasizes the importance of further research to identify and enhance this protective factor for cognitive preservation in both healthy and neurologically impaired older individuals.

HIGHLIGHTS

This review examines the concept of cognitive reserve in brain aging, in the context of dementia and its early stages. We have evaluated the methods commonly used to define and measure cognitive reserve. Sociobehavioral proxies, neuroimaging, and electrophysiological and genetic measures are discussed. The review emphasizes the importance of further research to identify and enhance this protective factor for cognitive preservation.

The concept of resilience to Alzheimer's Disease: current definitions and cellular and molecular mechanisms

Some individuals are able to maintain their cognitive abilities despite the presence of significant Alzheimer's Disease (AD) neuropathological changes. This discrepancy between cognition and pathology has been labeled as resilience and has evolved into a widely debated concept. External factors such as cognitive stimulation are associated with resilience to AD, but the exact cellular and molecular underpinnings are not completely understood. In this review, we discuss the current definitions used in the field, highlight the translational approaches used to investigate resilience to AD and summarize the underlying cellular and molecular substrates of resilience that have been derived from human and animal studies, which have received more and more attention in the last few years. From these studies the picture emerges that resilient individuals are different from AD patients in terms of specific pathological species and their cellular reaction to AD pathology, which possibly helps to maintain cognition up to a certain tipping point. Studying these rare resilient individuals can be of great importance as it could pave the way to novel therapeutic avenues for AD.

Cognitive aging and the life course: A new look at the Scaffolding theory

Our understanding of human neurocognitive aging, its developmental roots, and life course influences has been transformed by brain imaging technologies, increasing availability of longitudinal data sets, and analytic advances. The Scaffolding Theory of Aging and Cognition is a life course model, proposed originally in 2009, featuring adaptivity and compensatory potential as lifelong mechanisms for meeting neurocognitive challenges posed by the environment and by developing or declining brain circuitry. Here, we review the scaffolding theory in relation to new evidence addressing when during the life course potentially enriching and depleting factors exert their effects on brain health and scaffolding, and we consider the implications for separable, and potentially reciprocal, influences on the level of cognitive function and the rate of decline in later life.

Handicraft art leisure activities and cognitive reserve

ObjectiveOlder individuals face a higher likelihood of developing dementia. The rate of cognitive decline resulting from dementia is not equivalent for all, as some patients with dementia are able to function independently longer than others, despite having similar disease burden. The cognitive reserve (CR) theory provides one explanation for the differing rate of decline. CR suggests that there are factors-most notably, educational attainment and occupational attainment-that can protect against the cognitive decline. Although the beneficial effects of these notable CR factors are clear, not all are easily modifiable. Participation in leisure activities may represent a more easily modifiable factor. Some research hints at beneficial effects of leisure activities, although specific leisure activities have not been well examined. The present study examined the relations between handicraft art leisure activities (HALAs) and multiple cognitive domains. MethodArchival WAIS-IV and demographic data for 50 California retirement community residents were examined. ResultsHALA participation accounted for statistically significant variance in working memory performance (R2 = .40, β = .24%) over and above the established CR factors of age, depression, educational attainment, and occupational attainment. In addition, HALA participation was related to a better ability to perform abstract visual information tasks (Block Design subtest, r = .28, p = .05) and non-verbal reasoning tasks (Visual Puzzles subtest, r = .38, p = .008). ConclusionsHALA participation among older adults could contribute to the retention of cognitive function, supporting the role of HALA participation as a CR factor.

Estimation of cognitive reserve and its impact on cognitive performance in older adults

OBJECTIVES

Cognitive reserve provides evidence in the search for answers regarding the role that lifestyle has in the protection of cognition in old age. Through a structural equations model, different things were analyzed: the relative weight of education, occupational complexity, free time activities and the intelligence quotient in cognitive reserve; and its impact on three cognitive domains: memory, language and executive functions.

DESIGN

A trail analysis was executed, using structural equations procedure.

PARTICIPANTS

167 older participants (mean = 76.74 years, standard deviation = 6.8 years).

MEASUREMENTS

Participants were assessed with: Sociodemographic Questionnaire, Occupational Activity Agency Questionnaire, Social Participation Questionnaire and Neuropsychological Evaluation Battery for: memory, language and executive functions.

RESULTS

The cognitive reserve factor is well represented by the measures included, with values ​​between .43 and .86, and shows a direct effect on language (β = .52, p < .001), executive functions (β = .77, p <.001), and memory (β = .36, p = .003).

CONCLUSIONS

In conclusion, lifestyle factors, such as education, occupational complexity, leisure time activities and intelligence quotient have an impact on the conformation of cognitive reserve and performance in some psychological processes.

Changes in Body Mass Index and Incident Mild Cognitive Impairment Among African American Older Adults

BACKGROUND

Previous research suggests a decline in body mass index (BMI) among older adults is associated with negative health outcomes, including mild cognitive impairment (MCI) and incident dementia. However, no studies have examined the effects of education or developing MCI on BMI trajectories over time. The purpose of this investigation was to characterize trajectories of change in BMI among older adults who develop MCI.

METHODS

Participants were from the Minority Aging Research Study (MARS), a longitudinal cohort study of cognitive decline and Alzheimer's disease in older African Americans living in the greater Chicago, Illinois, area. The study included annual clinical evaluations of cognitive status, as well as measurements of height and weight for BMI calculation. Older African American participants without cognitive impairment at baseline were included in the present analysis (N = 436, 78% women, mean baseline age = 72 [SD = 5.7], mean education = 15 [SD = 3.5]).

RESULTS

In piecewise linear mixed-effects models that included a random intercept and 2 random slopes, BMI declined over time (B = -0.20, SE = 0.02, p < .001), with a faster decline after MCI diagnosis (additional decline, B = -0.15, SE = 0.06, p = .019). Older age was associated with lower baseline BMI (B = -0.19, SE = 0.05, p < .001), as was higher education (B = -0.34, SE = 0.09, p < .001). Further, higher education was associated with a slower decline in BMI before MCI (B = 0.02, SE = 0.006, p = .001), but a faster decline after MCI (B = -0.06, SE = 0.022, p = .003).

CONCLUSIONS

These results suggest an accelerated decline in BMI following an MCI diagnosis, with higher education related to an even faster BMI decline.

Associations between Education Years and Resting-state Functional Connectivity Modulated by APOE ε4 Carrier Status in Cognitively Normal Older Adults

Objective

: Cognitive reserve has emerged as a concept to explain the variable expression of clinical symptoms in the pathology of Alzheimer's disease (AD). The association between years of education, a proxy of cognitive reserve, and resting-state functional connectivity (rFC), a representative intermediate phenotype, has not been explored in the preclinical phase, considering risk factors for AD. We aimed to evaluate whether the relationship between years of education and rFC in cognitively preserved older adults differs depending on amyloid-beta deposition and APOE ε4 carrier status as effect modifiers.

Methods

: A total of 121 participants underwent functional magnetic resonance imaging, [18F] flutemetamol positron emission tomography-computed tomography, APOE genotyping, and a neuropsychological battery. Potential interactions between years of education and AD risk factors for rFC of AD-vulnerable neural networks were assessed with whole-brain voxel-wise analysis.

Results

: We found a significant education years-by-APOE ε4 carrier status interaction for the rFC from the seed region of the central executive (CEN) and dorsal attention networks. Moreover, there was a significant interaction of rFC between right superior occipital gyrus and the CEN seed region by APOE ε4 carrier status for memory performances and overall cognitive function.

Conclusion

: In preclinical APOE ε4 carriers, higher years of education were associated with higher rFC of the AD vulnerable network, but this contributed to lower cognitive function. These results contribute to a deeper understanding of the impact of cognitive reserve on sensitive functional intermediate phenotypic markers in the preclinical phase of AD.

Relationship between lifestyle proxies of cognitive reserve and cortical regions in older adults

Introduction

With the rapid increase in the population over 65 years old, research on healthy aging has become one of the priorities in the research community, looking for a cost-effective method to prevent or delay symptoms of mild cognitive disorder or dementia. Studies indicate that cognitive reserve theory could be beneficial in this regard. The aim of this study was to investigate the potential relationship between lifestyle socio-behavioral proxies of cognitive reserve and cortical regions in adults with no subjective cognitive decline.

Methods

Overall, 58 participants, aged 65-85 years, were included in the data analysis (M = 71.83, SD = 5.02, 20.7% male). Cognitive reserve proxies were measured using the Cognitive Reserve Index questionnaire, while cortical volumes were obtained with the Siemens 1.5 T Avanto MRI scanner and further mapped using the Desikan-Killiany-Tourville (DKT) Atlas. Estimated intracranial volume and age were used as covariates.

Results

The results indicated that higher occupational complexity was associated with larger cortical volume in the left middle temporal gyrus, the left and right inferior temporal gyrus, and the left inferior parietal lobule, while a combined proxy (the total CRI score) showed a positive relationship with the volume of left middle temporal gyrus and inferior parietal lobule, and pars orbitalis in the right hemisphere.

Discussion

These results might indicate that more complex occupational activities and overall more intellectually and socially active life-style could contribute to better brain health, especially in regions known to be more vulnerable to Alzheimer's disease.

The role of cognitive reserve in traumatic brain injury: a systematic review of observational studies

OBJECTIVE

Evaluate the role of cognitive reserve (CR) on cognitive and physical sequelae in traumatic brain injury (TBI).

METHODS

A comprehensive search strategy was conducted in four databases in English and Spanish in the last 12 years (2011-2023). Inclusion criteria: original cross-sectional and longitudinal studies whose main or secondary objective was to evaluate the effect of CR in adult patients with TBI. PRISMA guidelines were used to report the search and selection method and STROBE checklist was used to evaluate the quality of studies.

RESULTS

Eighteen observational studies were included in this review. Multiple sources of variability were observed: number of patients, time of evolution, severity of the TBI, type of CR proxy, cognitive assessment instrument, etc. However, the most commonly used indicators of CR were premorbid IQ and educational attainment. A positive and consistent association between CR and performance on cognitive tests after injury was found.

CONCLUSIONS

CR has a consistent positive effect on cognition and on some other aspects of recovery in traumatic brain injury. In future studies, it will be necessary to promote the use of CR indices based on various indicators and explore the effects of CR on other aspects related to the recovery of brain trauma.

Unraveling the Threads: Sleep Difficulties, Neighborhood Physical Disorder, and Subjective Cognitive Decline in Older Americans

Background

Research suggests that the neighborhood in which people live can be a risk or protective factor for various health outcomes, including cognitive decline to Alzheimer's disease. Similar to the impact of neighborhood on health outcomes, sleep difficulties have been linked to cognitive function in older adults. However, few studies have examined how neighborhood physical disorders moderate the effects of sleep on subjective cognitive decline (SCD).

Objective

The study examined the moderating effect of neighborhood factors on the relationship between sleep difficulties and SCD.

Methods

Data were obtained from 2,494 respondents (1,065 males and 1,429 females) from Wave 11 of the National Health and Aging Trends (NHATS) data. Sleep difficulties were operationalized as the presence of difficulties in falling and staying asleep. Neighborhood physical disorder (e.g., vandalism, graffiti) was based on interviewer observations of respondents' neighborhoods. SCD was operationalized as subjective reports of increasing or worse memory loss in the past 12 months and present memory rating. We utilized Linear regression to test neighborhood physical disorder as a moderator of the relationship between sleep difficulties and SCD.

Results

We found a significant interaction between sleep difficulties and neighborhood physical disorder on SCD (β=0.046, p = 0.031, 95% CI[0.00,0.51], p < 0.001). Participants who reported higher average sleep difficulties and higher levels of neighborhood physical disorder were more likely to report SCD.

Conclusions

Our findings add to inform future health interventions and policy recommendations that address modifiable sources of cognitive decline and risk of Alzheimer's disease.

Measures of cognitive reserve: An umbrella review

Objective: Recently, there has been a growing interest in operationalizing and measuring cognitive reserve (CR) for clinical and research purposes. This umbrella review aims to summarize the existing systematic and meta-analytic reviews about measures of CR. Method: A literature search was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and the guidelines of Aromataris et al. (2015) to identify the systematic reviews and meta-analysis involving the assessment of CR. The methodological quality of the papers included in this umbrella review was assessed with A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR-2) and Specialist Unit for Review Evidence (SURE). Results: Thirty-one reviews were identified, sixteen of which were systematic reviews, and fifteen were meta-analyses. Most of the reviews had a critically low quality, according to AMSTAR-2. The reviews included between two and 135 studies. Most of the papers focused on older adults, mainly those with dementia. CR was measured using one to six proxies, but most considered each proxy separately. The most assessed proxies of CR were education on its own, combined with occupation and/or engagement in activities or combined with parental education, bilingualism, and engagement in activities when four CR proxies were studied. Most of the studies included in higher quality reviews focused on three proxies, with education and engagement in activities being the most evaluated using CR questionnaires. Conclusion: Despite the growing interest in measuring CR, its operationalization did not improve since the last umbrella review in this field.

The role of cognitive reserve in mediating HIV-associated neurocognitive disorders in older adults living with-treated HIV in Mbeya, Tanzania: A cross-sectional observational study

INTRODUCTION

HIV-associated neurocognitive disorders (HAND) are a spectrum of cognitive impairments in chronic HIV infection. HAND is common in sub-Saharan Africa (SSA), despite combination antiretroviral therapy (cART). Older people appear to be at increased risk. It is unknown if cognitive reserve (CR), which is protective in neurodegenerative dementias, protects against HAND.

OBJECTIVE

To evaluate the association of CR and risk of HAND in an older cART-treated population in SSA.

METHODS

Cross-sectional observational study completed in hospital outpatient clinics in Southwest Tanzania. We assessed HIV-positive participants aged ≥50 years established on cART using a neuropsychological test battery, functional assessment, informant history and depression screen. Control participants were HIV-negative individuals attending chronic disease clinics. We used operationalised Frascati criteria for HAND diagnosis. CR was measured using the Cognitive Reserve Index (CRI) and other proxy measures.

RESULTS

The prevalence of HAND was 64.4% (n = 219/343). Lower CRI score [odds ratio (OR) = 0.971, p = 0.009] and less formal education (OR = 4.364, p = 0.026) were independent risk factors for HAND but HIV-severity measures were not. Unemployment and low-skilled manual work were associated with increased risk of HAND in bivariate analysis but not in multivariable analysis.

CONCLUSIONS

Higher total CRI score and more formal education appeared to be protective against HAND, in this cohort. Potentially, cognitively and socially stimulating activities and exercise could increase cognitive reserve in later life. Cognitive reserve could possibly be more important than HIV-disease severity in risk of HAND in older people with treated HIV.

Depressive Symptomatology as a Predictor of Cognitive Impairment: Evidence from the Korean Longitudinal Study of Aging (KLOSA), 2006-2020

Depressive symptoms are recognized as risk factors for cognitive impairment with intricate underlying biological mechanisms. We explored the link between depressive symptoms and cognitive impairment onset; we also assessed how this association is influenced by educational levels. This study included 5843 individuals aged ≥45 years, comprising 27,908 observations from 2006 to 2020. Based on repeated measurements of each participant, we estimated the association between depressive symptoms and cognitive impairment onset after a 2-year follow-up by using generalized estimating equations. The incidence rate was 9.4% among those individuals without depressive symptoms, which was in contrast with a rate of 21.0% among those individuals experiencing depressive symptoms. The odds ratio (OR) (95% confidence interval [CI]) for the association between depressive symptoms and cognitive impairment onset in the overall sample was 1.61 (1.47-1.76). This association was more pronounced among individuals with higher educational levels. Specifically, the OR (95% CI) of the association between depressive symptoms and cognitive impairment was highest among individuals with a college education (2.60 [1.78-3.81]), and the association was lowest among individuals with elementary or no education levels (1.45 [1.28-1.63]). Our findings highlight the idea that although individuals with higher educational backgrounds exhibit a diminished risk of cognitive impairment, the detrimental impacts of depressive symptoms on cognitive performance are particularly more pronounced within this group.

Neurocognitive Recovery in Abstinent Patients with Alcohol Use Disorder: A Scoping Review for Associated Factors

Objective

Studies have reported inconsistent results regarding the extent to which neurocognitive recovery occurs in abstinent patients with alcohol use disorder (AUD). In addition to abstinence, other factors may have influenced this process and contributed to the inconsistencies. This review examines the factors investigated in this regard and describes the possible influence of each factor based on the evidence collected.

Methodology

PubMed was systematically searched for articles published between January 2000 and July 2023. Longitudinal humane studies investigating neurocognitive recovery in abstinent adult AUD patients were included. Studies with a cross-sectional design were excluded, as were studies that did not classify AUD according to the DSM-IV or 5 criteria, only examined binge use, did not report neuropsychological outcomes or duration of abstinence, or where neurological disorders were present.

Results

Sixteen categories of factors were distinguished from 31 full-text articles. Consistent patterns were found, indicating an association between neurocognitive recovery and the "smoking" and 'brain volume" factors. Consistent patterns were also found indicating that there is no relationship with "quantities of alcohol used" and "education level." A similar consistent pattern was also found for "polysubstance use", "gender" and "verbal reading", but the number of studies is considered limited. The association with "age" is studied frequently but with inconsistent findings. The remaining eight factors were regarded as understudied.

Conclusion

The clearest patterns emerging from the evidence are a predominantly negative influence of smoking on neurocognitive recovery, associations between changes in brain area volume and neurocognitive recovery, and no association between neurocognitive recovery and the amount of alcohol consumed, as measured by self-report, nor with educational attainment. Future research on the understudied factors and factors with inconsistent evidence is needed, preferably through longitudinal designs with multiple assessment periods starting after at least two weeks of abstinence.

Determinants of cognitive and brain resilience to tau pathology: a longitudinal analysis

Mechanisms of resilience against tau pathology in individuals across the Alzheimer's disease spectrum are insufficiently understood. Longitudinal data are necessary to reveal which factors relate to preserved cognition (i.e. cognitive resilience) and brain structure (i.e. brain resilience) despite abundant tau pathology, and to clarify whether these associations are cross-sectional or longitudinal. We used a longitudinal study design to investigate the role of several demographic, biological and brain structural factors in yielding cognitive and brain resilience to tau pathology as measured with PET. In this multicentre study, we included 366 amyloid-β-positive individuals with mild cognitive impairment or Alzheimer's disease dementia with baseline 18F-flortaucipir-PET and longitudinal cognitive assessments. A subset (n = 200) additionally underwent longitudinal structural MRI. We used linear mixed-effects models with global cognition and cortical thickness as dependent variables to investigate determinants of cognitive resilience and brain resilience, respectively. Models assessed whether age, sex, years of education, APOE-ε4 status, intracranial volume (and cortical thickness for cognitive resilience models) modified the association of tau pathology with cognitive decline or cortical thinning. We found that the association between higher baseline tau-PET levels (quantified in a temporal meta-region of interest) and rate of cognitive decline (measured with repeated Mini-Mental State Examination) was adversely modified by older age (Stβinteraction = -0.062, P = 0.032), higher education level (Stβinteraction = -0.072, P = 0.011) and higher intracranial volume (Stβinteraction = -0.07, P = 0.016). Younger age, higher education and greater cortical thickness were associated with better cognitive performance at baseline. Greater cortical thickness was furthermore associated with slower cognitive decline independent of tau burden. Higher education also modified the negative impact of tau-PET on cortical thinning, while older age was associated with higher baseline cortical thickness and slower rate of cortical thinning independent of tau. Our analyses revealed no (cross-sectional or longitudinal) associations for sex and APOE-ε4 status on cognition and cortical thickness. In this longitudinal study of clinically impaired individuals with underlying Alzheimer's disease neuropathological changes, we identified education as the most robust determinant of both cognitive and brain resilience against tau pathology. The observed interaction with tau burden on cognitive decline suggests that education may be protective against cognitive decline and brain atrophy at lower levels of tau pathology, with a potential depletion of resilience resources with advancing pathology. Finally, we did not find major contributions of sex to brain nor cognitive resilience, suggesting that previous links between sex and resilience might be mainly driven by cross-sectional differences.

Effects of Controlled Supramaximal High-Intensity Interval Training on Cardiorespiratory Fitness and Global Cognitive Function in Older Adults: The Umeå HIT Study-A Randomized Controlled Trial

BACKGROUND

This study examined the effects of regulated and controlled supramaximal high-intensity interval training (HIT) adapted for older adults, compared to moderate-intensity training (MIT), on cardiorespiratory fitness; cognitive, cardiovascular, and muscular function; and quality of life.

METHODS

Sixty-eight nonexercising older adults (66-79 years, 44% males) were randomized to 3 months of twice-weekly HIT (20-minute session including 10 × 6-second intervals) or MIT (40-minute session including 3 × 8-minute intervals) on stationary bicycles in an ordinary gym setting. Individualized target intensity was watt controlled with a standardized pedaling cadence and individual adjustment of the resistance load. Primary outcomes were cardiorespiratory fitness (V̇o2peak) and global cognitive function (unit-weighted composite).

RESULTS

V̇o2peak increased significantly (mean 1.38 mL/kg/min, 95% CI [0.77, 1.98]), with no between-group difference (mean difference 0.05 [-1.17, 1.25]). Global cognition did not improve (0.02 [-0.05, 0.09]), nor differed between groups (0.11 [-0.03, 0.24]). Significant between-group differences in change were observed for working memory (0.32 [0.01, 0.64]), and maximal isometric knee extensor muscle strength (0.07 N·m/kg [0.003, 0.137]), both in favor of HIT. Irrespective of the group, there was a negative change in episodic memory (-0.15 [-0.28, -0.02]), a positive change in visuospatial ability (0.26 [0.08, 0.44]), and a decrease in systolic (-2.09 mmHg [-3.54, -0.64]) and diastolic (-1.27 mmHg [-2.31, -0.25]) blood pressure.

CONCLUSIONS

In nonexercising older adults, 3 months of watt-controlled supramaximal HIT improved cardiorespiratory fitness and cardiovascular function to a similar extent as MIT, despite half the training time. In favor of HIT, there was an improvement in muscular function and a potential domain-specific effect on working memory.

CLINICAL TRIAL REGISTRATION

NCT03765385.

Effect of apolipoprotein genotype and educational attainment on cognitive function in autosomal dominant Alzheimer's disease

Autosomal dominant Alzheimer's disease (ADAD) is genetically determined, but variability in age of symptom onset suggests additional factors may influence cognitive trajectories. Although apolipoprotein E (APOE) genotype and educational attainment both influence dementia onset in sporadic AD, evidence for these effects in ADAD is limited. To investigate the effects of APOE and educational attainment on age-related cognitive trajectories in ADAD, we analyzed data from 675 Presenilin-1 E280A mutation carriers and 594 non-carriers. Here we show that age-related cognitive decline is accelerated in ADAD mutation carriers who also have an APOE e4 allele compared to those who do not and delayed in mutation carriers who also have an APOE e2 allele compared to those who do not. Educational attainment is protective and moderates the effect of APOE on cognition. Despite ADAD mutation carriers being genetically determined to develop dementia, age-related cognitive decline may be influenced by other genetic and environmental factors.

Improved connectivity and cognition due to cognitive stimulation in Alzheimer's disease

Background

Due to the increasing prevalence of Alzheimer's disease (AD) and the limited efficacy of pharmacological treatment, the interest in non-pharmacological interventions, e.g., cognitive stimulation therapy (CST), to improve cognitive dysfunction and the quality of life of AD patients are on a steady rise.

Objectives

Here, we examined the efficacy of a CST program specifically conceptualized for AD dementia patients and the neural mechanisms underlying cognitive or behavioral benefits of CST.

Methods

Using neuropsychological tests and MRI-based measurements of functional connectivity, we examined the (neuro-) psychological status and network changes at two time points: pre vs. post-stimulation (8 to 12 weeks) in the intervention group (n = 15) who received the CST versus a no-intervention control group (n = 15).

Results

After CST, we observed significant improvement in the Mini-Mental State Examination (MMSE), the Alzheimer's Disease Assessment Scale, cognitive subsection (ADAS-cog), and the behavioral and psychological symptoms of dementia (BPSD) scores. These cognitive improvements were associated with an up-regulated functional connectivity between the left posterior hippocampus and the trunk of the left postcentral gyrus.

Conclusion

Our data indicate that CST seems to induce short-term global cognition and behavior improvements in mild to moderate AD dementia and enhances resting-state functional connectivity in learning- and memory-associated brain regions. These convergent results prove that even in mild to moderate dementia AD, neuroplasticity can be harnessed to alleviate cognitive impairment with CST.

Recommendations on Social Determinants of Health in Neurologic Disease

Social determinants of health (SDOH) are increasingly recognized as important drivers of inequities in neurologic disease and outcomes. However, our understanding of the biopsychosocial mechanisms by which SDOH affect neurologic disease remains in its infancy. The most robust epidemiologic research has been on the associations between education, schooling, and place-based social determinants on cognition, dementia, and cerebrovascular disease later in life. Further research is needed to more deeply understand the complex interplay of SDOH on neurologic disease. Few SDOH screening tools have been validated in populations with neurologic disease. In addition, comparison across studies and populations is hampered by lack of standardized common data elements. Experiences of populations historically underrepresented in research should be centered in future research studies, and changes should be made in recruitment expectations and measurement choices. For research on inequities, it is critical to support and incentivize institutional infrastructure to foster meaningful engagement with populations affected by research. Finally, it remains to be seen whether individual-level health or behavioral interventions or place-level, systemic or policy interventions to reduce population burden will be most effective in reducing inequities in neurologic disease and outcomes. Although numerous clinical trials have focused on addressing downstream SDOH such as health literacy and health behaviors (e.g., medication adherence, physical activity, diet), few have addressed upstream, structural determinants which may have a more profound impact on addressing inequities in neurologic disease. Ultimately, further research is needed to determine which specific SDOH should be targeted and how, when, and by whom they should be addressed to improve neurologic outcomes.

Mendelian randomization evidence for the causal effects of socio-economic inequality on human longevity among Europeans

Human longevity correlates with socio-economic status, and there is evidence that educational attainment increases human lifespan. However, to inform meaningful health policies, we need fine-grained causal evidence on which dimensions of socio-economic status affect longevity and the mediating roles of modifiable factors such as lifestyle and disease. Here we performed two-sample Mendelian randomization analyses applying genetic instruments of education, income and occupation (n = 248,847 to 1,131,881) to estimate their causal effects and consequences on parental lifespan and self-longevity (n = 28,967 to 1,012,240) from the largest available genome-wide association studies in populations of European ancestry. Each 4.20 years of additional educational attainment were causally associated with a 3.23-year-longer parental lifespan independently of income and occupation and were causally associated with 30-59% higher odds of self-longevity, suggesting that education was the primary determinant. By contrast, each one-standard-deviation-higher income and one-point-higher occupation was causally associated with 3.06-year-longer and 1.29-year-longer parental lifespans, respectively, but not independently of the other socio-economic indicators. We found no evidence for causal effects of income or occupation on self-longevity. Mediation analyses conducted in predominantly European-descent individuals through two-step Mendelian randomization suggested that among 59 candidates, cigarettes per day, body mass index, waist-to-hip ratio, hypertension, coronary heart disease, myocardial infarction, stroke, Alzheimer's disease, type 2 diabetes, heart failure and lung cancer individually played substantial mediating roles (proportion mediated, >10%) in the effect of education on specific longevity outcomes. These findings inform interventions for remediating longevity disparities attributable to socio-economic inequality.

Social Health and Change in Cognitive Capability among Older Adults: Findings from Four European Longitudinal Studies

INTRODUCTION

In this study, we examine whether social health markers measured at baseline are associated with differences in cognitive capability and the rate of cognitive decline over an 11-to-18-year period among older adults and compare results across studies.

METHODS

We applied an integrated data analysis approach to 16,858 participants (mean age 65 years; 56% female) from the National Survey for Health and Development (NSHD), the English Longitudinal Study of Aging (ELSA), the Swedish National Study on Aging and Care in Kungsholmen (SNAC-K), and the Rotterdam Study. We used multilevel models to examine social health in relation to cognitive capability and the rate of cognitive decline.

RESULTS

Pooled estimates show distinct relationships between markers of social health and cognitive domains, e.g., a large network size (≥6 people vs. none) was associated with higher executive function (0.17 standard deviation [SD] [95% CI: 0.00, 0.34], I2 = 27%) but not with memory (0.08 SD [95% CI: -0.02, 0.18], I2 = 19%). We also observed pooled associations between being married or cohabiting, having a large network size, and participating in social activities with slower decline in cognitive capability. However, estimates were close to zero, e.g., 0.01 SD/year (95% CI: 0.01, 0.02) I2 = 19% for marital status and executive function. There were clear study-specific differences: results for average processing speed were the most homogenous, and results for average memory were the most heterogeneous.

CONCLUSION

Overall, markers of good social health have a positive association with cognitive capability. However, we found differential associations between specific markers of social health and cognitive domains and differences between studies. These findings highlight the importance of examining between-study differences and considering the context specificity of findings in developing and deploying interventions.

Educational Attainment and Dementia: Mediation by Mid-Life Vascular Risk Factors

INTRODUCTION

Lower education is associated with higher burden of vascular risk factors in mid-life and higher risk of dementia in late life. We aim to understand the causal mechanism through which vascular risk factors potentially mediate the relationship between education and dementia.

METHODS

In a cohort of 13,368 Black and White older adults in the Atherosclerosis Risk in Communities Study, we assessed the relationship between education (grade school, high school without graduation, high school graduate or equivalent, college, graduate/professional school) and dementia among all participants and among those with incident stroke. Cox models were adjusted for age, race-center (a variable stratified by race and field center), sex, apolipoprotein E (APOE) ε4 genotype, and family history of cardiovascular disease. Causal mediation models assessed mediation by mid-life systolic blood pressure, fasting blood glucose, body mass index, and smoking.

RESULTS

More education was associated with 8 to 44% lower risk of dementia compared to grade school-level education in a dose-response pattern, while the relationship between education and post-stroke dementia was not statistically significant. Up to 25% of the association between education and dementia was mediated through mid-life vascular risk factors, with a smaller percentage mediated for lower levels of education.

INTERPRETATION

A substantial proportion of the relationship between education and dementia was mediated through mid-life vascular risk factors. However, risk factor modification is unlikely to fully address the large educational disparities in dementia risk. Prevention efforts must also address disparities in socioeconomic resources leading to divergent early-life education and other structural determinants of mid-life vascular risk factors. ANN NEUROL 2023;94:13-26.

Life course engagement in enriching activities: When and how does it matter for cognitive aging?

Growing evidence suggests that participation in enriching activities (physical, social, and mental) across the life course is beneficial for cognitive functioning in older age. However, few studies have examined the effects of enrichment across the entire life course within the same participants. Using 2,931 participants in the Health and Retirement Study, we linked self-report data from later life and retrospective self-report data from early life and midlife to cognitive performance after Age 65. We categorized participants as having either high (top ∼25%) or average to low (bottom ∼75%) level of enrichment during each life period. Thus, eight groups were identified that reflected unique patterns of enrichment during early, mid, and later life (e.g., high-high-high). Using growth curve modeling, we found that life course enrichment patterns predicted both cognitive functioning and the rate of cognitive decline across five time points spanning 8 years (Aim 1). Groups with high enrichment during at least one life period had higher performance and slower decline in older age, compared to those who had average to low levels of enrichment throughout all three life periods. We also found that high enrichment during each life period independently predicted better cognitive performance and that high enrichment during early and later life also predicted slower cognitive decline (Aim 2). These findings support the idea that high enrichment is beneficial for cognition in later life and that the effects are long-lasting, even when individuals are inconsistent in enrichment engagement throughout the entire life course. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Association between previous cataract surgery and cognition among middle-aged and older Chinese: the China health and retirement longitudinal study (CHARLS)

BACKGROUND

Cataract is the primary cause of blindness globally, and surgery offers the only method by which to remove cataracts. We aimed to examine whether previous cataract surgery is associated with cognitive function.

METHODS

Our study included 13,824 participants. Data from the baseline of the China Health and Retirement Longitudinal Study (CHARLS) were used. The participants were categorized into two groups: with and without previous cataract surgery. Weighted multiple linear regression was used to obtain the β and 95% confidence intervals (CI).

RESULTS

The participants who had previous cataract surgery (n = 261) scored lower in cognition, including both memory and mental state, than those without previous cataract surgery. After adjusting for socioeconomic factors and metabolic measures, a negative association was evident between previous cataract surgery and cognition (β = -0.647, 95% CI: -1.244, - 0.049). Furthermore, the participants who were older and female demonstrated a decline in cognition, while living in cities and having higher levels education were associated with higher cognition.

CONCLUSIONS

Better cognitive function was associated with less previous cataract surgery or cataract occurrence. This suggests that a period of vision loss due to cataract leads to cognitive decline, however further studies are need to dissect the impact of vision loss and cataract surgery on cognitive decline.

Dual-stage cognitive assessment: a two-stage screening for cognitive impairment in primary care

BACKGROUND

Aging population has led to an increased proportion of older adults and cognitively impaired. We designed a brief and flexible two-stage cognitive screening scale, the Dual-Stage Cognitive Assessment (DuCA), for cognitive screening in primary care settings.

METHOD

In total, 1,772 community-dwelling participants were recruited, including those with normal cognition (NC, n = 1,008), mild cognitive impairment (MCI, n = 633), and Alzheimer's disease (AD, n = 131), and administered a neuropsychological test battery and the DuCA. To improve performance, the DuCA combines visual and auditory memory tests for an enhanced memory function test.

RESULTS

The correlation coefficient between DuCA-part 1 and DuCA-total was 0.84 (P < 0.001). The correlation coefficients of DuCA-part 1 with Addenbrooke's Cognitive Examination III (ACE-III) and Montreal Cognitive Assessment Basic (MoCA-B) were 0.66 (P < 0.001) and 0.85 (P < 0.001), respectively. The correlation coefficients of DuCA-total with ACE-III and MoCA-B were 0.78 (P < 0.001) and 0.83 (P < 0.001), respectively. DuCA-Part 1 showed a similar discrimination ability for MCI from NC (area under curve [AUC] = 0.87, 95%CI 0.848-0.883) as ACE III (AUC = 0.86, 95%CI 0.838-0.874) and MoCA-B (AUC = 0.85, 95%CI 0.830-0.868). DuCA-total had a higher AUC (0.93, 95%CI: 0.917-0.942). At different education levels, the AUC was 0.83-0.84 for DuCA-part 1, and 0.89-0.94 for DuCA-total. DuCA-part 1 and DuCA-total's ability to discriminate AD from MCI was 0.84 and 0.93, respectively.

CONCLUSION

DuCA-Part 1 would aid rapid screening and supplemented with the second part for a complete assessment. DuCA is suited for large-scale cognitive screening in primary care, saving time and eliminating the need for extensively training assessors.

Deciphering the clinico-radiological heterogeneity of dysexecutive Alzheimer's disease

Dysexecutive Alzheimer's disease (dAD) manifests as a progressive dysexecutive syndrome without prominent behavioral features, and previous studies suggest clinico-radiological heterogeneity within this syndrome. We uncovered this heterogeneity using unsupervised machine learning in 52 dAD patients with multimodal imaging and cognitive data. A spectral decomposition of covariance between FDG-PET images yielded six latent factors ("eigenbrains") accounting for 48% of variance in patterns of hypometabolism. These eigenbrains differentially related to age at onset, clinical severity, and cognitive performance. A hierarchical clustering on the eigenvalues of these eigenbrains yielded four dAD subtypes, i.e. "left-dominant," "right-dominant," "bi-parietal-dominant," and "heteromodal-diffuse." Patterns of FDG-PET hypometabolism overlapped with those of tau-PET distribution and MRI neurodegeneration for each subtype, whereas patterns of amyloid deposition were similar across subtypes. Subtypes differed in age at onset and clinical severity where the heteromodal-diffuse exhibited a worse clinical picture, and the bi-parietal had a milder clinical presentation. We propose a conceptual framework of executive components based on the clinico-radiological associations observed in dAD. We demonstrate that patients with dAD, despite sharing core clinical features, are diagnosed with variability in their clinical and neuroimaging profiles. Our findings support the use of data-driven approaches to delineate brain-behavior relationships relevant to clinical practice and disease physiology.

Changes in Plant-based Dietary Quality and Subsequent Risk of Cognitive Impairment among Older Chinese Adults: A National Community-based Cohort Study

BACKGROUND

It is unclear how changes in plant-based dietary quality are linked to subsequent risk of cognitive impairment. This study aims to evaluate this relationship using data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS).

METHODS

A total of 6662 participants free of cognitive impairment in 2008 were included and followed up to 2018. Plant-based dietary quality was assessed by three indices: overall plant-based diet index (PDI), healthful plant-based diet index (hPDI), and unhealthful plant-based diet index (uPDI). Changes in plant-based diet quality from 2008 to 2011 were classified into quintiles. We assessed incident cognitive impairment (from 2011 to 2018) by using the Mini-Mental State Examination (MMSE). Cox proportional-hazards models were performed.

RESULTS

We recorded 1571 incident cases of cognitive impairment during a median of 10 years of follow-up. Compared with participants whose plant-based diet had no change or was relatively stable over three years, the full-adjusted hazard ratios (HRs) with 95% confidence intervals (CI) for cognitive impairment were 0.77 (0.64, 0.93), 0.72 (0.60, 0.86), and 1.50 (1.27, 1.77) among participants with a large increase in PDI, hPDI, and uPDI, respectively. The HRs with 95% CI were 1.22 (1.02, 1.44), 1.30 (1.11, 1.54), and 0.80 (0.67, 0.96) among participants with a large decrease in PDI, hPDI, and uPDI, respectively. Every 10-point increase in PDI and hPDI was associated with 26% and 30% lower risk of cognitive impairment, while every 10-point increase in uPDI was associated with 36% higher risk.

CONCLUSIONS

Older adults with increased adherence to an overall plant-based diet and a healthful plant-based diet over three years have a lower risk of cognitive impairment, while those with increased adherence to an unhealthy plant-based diet had a higher risk of cognitive impairment.

Cognitive reserve as a moderator of outcomes in five clusters of first episode psychosis patients: a 10-year follow-up study of the PAFIP cohort

BACKGROUND

Cognitive reserve (CR) has been associated with the development and prognosis of psychosis. Different proxies have been used to estimate CR among individuals. A composite score of these proxies could elucidate the role of CR at illness onset on the variability of clinical and neurocognitive outcomes.

METHODS

Premorbid intelligence quotient (IQ), years of education and premorbid adjustment were explored as proxies of CR in a large sample (N = 424) of first-episode psychosis (FEP) non-affective patients. Clusters of patients were identified and compared based on premorbid, clinical and neurocognitive variables at baseline. Additionally, the clusters were compared at 3-year (N = 362) and 10-year (N = 150) follow-ups.

RESULTS

The FEP patients were grouped into five CR clusters: C1 (low premorbid IQ, low education and poor premorbid) 14%; C2 (low premorbid IQ, low education and good premorbid adjustment) 29%; C3 (normal premorbid IQ, low education and poor premorbid adjustment) 17%; C4 (normal premorbid IQ, medium education and good premorbid adjustment) 25%; and C5 (normal premorbid IQ, higher education and good premorbid adjustment) 15%. In general, positive and negative symptoms were more severe in the FEP patients with the lowest CR at baseline and follow-up assessments, while those with high CR presented and maintained higher levels of cognitive functioning.

CONCLUSIONS

CR could be considered a key factor at illness onset and a moderator of outcomes in FEP patients. A high CR could function as a protective factor against cognitive impairment and severe symptomatology. Clinical interventions focused on increasing CR and documenting long-term benefits are interesting and desirable.

Neuropsychological Functions and Audiological Findings in Elderly Cochlear Implant Users: The Role of Attention in Postoperative Performance

Objectives: The present study aimed to investigate in a group of elderly CI users working memory and attention, conventionally considered as predictors of better CI performance and to try to disentangle the effects of these cognitive domains on speech perception, finding potential markers of cognitive decline related to audiometric findings. Methods Thirty postlingually deafened CI users aged >60 underwent an audiological evaluation followed by a cognitive assessment of attention and verbal working memory. A correlation analysis was performed to evaluate the associations between cognitive variables while a simple regression investigated the relationships between cognitive and audiological variables. Comparative analysis was performed to compare variables on the basis of subjects’ attention performance. Results: Attention was found to play a significant role in sound field and speech perception. Univariate analysis found a significant difference between poor and high attention performers, while regression analysis showed that attention significantly predicted recognition of words presented at Signal/Noise +10. Further, the high attention performers showed significantly higher scores than low attentional performers for all working memory tasks. Conclusion: Overall findings confirmed that a better cognitive performance may positively contribute to better speech perception outcomes, especially in complex listening situations. WM may play a crucial role in storage and processing of auditory-verbal stimuli and a robust attention may lead to better performance for speech perception in noise. Implementation of cognitive training in auditory rehabilitation of CI users should be investigated in order to improve cognitive and audiological performance in elderly CI users.

2023 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease, including prevalence and incidence, mortality and morbidity, use and costs of care, and the overall impact on family caregivers, the dementia workforce and society. The Special Report examines the patient journey from awareness of cognitive changes to potential treatment with drugs that change the underlying biology of Alzheimer's. An estimated 6.7 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060 barring the development of medical breakthroughs to prevent, slow or cure AD. Official death certificates recorded 121,499 deaths from AD in 2019, and Alzheimer's disease was officially listed as the sixth-leading cause of death in the United States. In 2020 and 2021, when COVID-19 entered the ranks of the top ten causes of death, Alzheimer's was the seventh-leading cause of death. Alzheimer's remains the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2019, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 145%. This trajectory of deaths from AD was likely exacerbated by the COVID-19 pandemic in 2020 and 2021. More than 11 million family members and other unpaid caregivers provided an estimated 18 billion hours of care to people with Alzheimer's or other dementias in 2022. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $339.5 billion in 2022. Its costs, however, extend to family caregivers' increased risk for emotional distress and negative mental and physical health outcomes - costs that have been aggravated by COVID-19. Members of the paid health care workforce are involved in diagnosing, treating and caring for people with dementia. In recent years, however, a shortage of such workers has developed in the United States. This shortage - brought about, in part, by COVID-19 - has occurred at a time when more members of the dementia care workforce are needed. Therefore, programs will be needed to attract workers and better train health care teams. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are almost three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 22 times as great. Total payments in 2023 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $345 billion. The Special Report examines whether there will be sufficient numbers of physician specialists to provide Alzheimer's care and treatment now that two drugs are available that change the underlying biology of Alzheimer's disease.

Diversity in verbal fluency performance and its associations with MRI-informed brain age matrices in normal ageing and neurocognitive disorders

INTRODUCTION

Category verbal fluency test (CVFT) has been widely used to assess and monitor the cognitive capacities in epidemiological studies and clinical trials. Pronounced discrepancy in CVFT performance has been found in individuals with different cognitive statuses. This study aimed to combine the psychometric and morphometric approaches to decode the complex verbal fluency performance in senior adults with normal ageing and neurocognitive disorders.

METHODS

This study adopted a two-stage cross-sectional design involving quantitative analyses of neuropsychological and neuroimaging data. In study I, capacity- and speed-based measures of CVFT were developed to evaluate the verbal fluency performance in normal ageing seniors (n = 261), those with mild cognitive impairment (n = 204), and those with dementia (n = 23) whose age range is from 65 to 85 years. In study II, structural magnetic resonance imaging-informed gray matter volume (GMV) and brain age matrices were calculated in a subsample (n = 52) from Study I through surface-based morphometry analysis. With age and gender as covariates, Pearson's correlation analysis was used to examine the associations of CVFT measures, GMV, and brain age matrices.

RESULTS

Speed-based measures showed extensive and stronger associations with other cognitive functions than capacity-based measures. The component-specific CVFT measures showed shared and unique neural underpinnings with lateralized morphometric features. Moreover, the increased CVFT capacity was significantly correlated with younger brain age in mild neurocognitive disorder (NCD) patients.

CONCLUSION

We found that the diversity of verbal fluency performance in normal ageing and NCD patients could be explained by a combination of memory, language, and executive abilities. The component-specific measures and related lateralized morphometric correlates also highlight the underlying theoretical meaning of verbal fluency performance and its clinical utility in detecting and tracing the cognitive trajectory in individuals with accelerated ageing.

Cognitive decline sensitivity by educational level and residential area: A descriptive study using long-term care insurance dementia registration data in South Korea

In South Korea Long-Term Care Insurance (LTCI) system, the special dementia rating (SDR) is a registration grading for dementia patients who do not have a physical disability or functional restrictions and is the first applicable registration following the diagnosis of dementia. We investigated the differences in age of registration of SDR and age of dementia diagnosis according to the educational level and residential area. This was a retrospective, cross-sectional study using the Korean National Health Insurance Service dataset. Applications for SDR between July 2014 and December 2016 were identified for participant selection, and 32,352 patients with dementia were included. Educational levels were defined as follows: the illiterate, only-reading, 1 to 6 years, 6 to 12 years, and ≥12 years. Urban residents were those who lived in the city, as ascertained from the Korean administrative district system. The primary outcomes were ages at the time of dementia diagnosis and SDR registration. A lower education level significantly correlated with a higher proportion of older adults, but a higher number of years of education significantly increased with the proportion of males and urban residents (P < .001 for all). A higher education level was inversely associated with the age at diagnosis of dementia (P < .001) and at the registration of SDR (P < .001). Urban residents were diagnosed with dementia at a significantly lower age and registered for SDR earlier than rural residents (P < .001 for both). Both urban and rural residents consistently showed that a higher educational level was associated with lower age at the dementia diagnosis and SDR registration. Patients who were highly educated and living in urban areas were diagnosed with dementia and registered on SDR when they were relatively younger, indicating that cognitive decline sensitivity and medical accessibility are related to earlier dementia diagnosis and registration.