Education and dementia: a meta-analytic study

Predictors of dementia among the oldest old: longitudinal findings from the representative "survey on quality of life and subjective well-being of the very old in North Rhine-Westphalia (NRW80+)"

BACKGROUND/AIMS

Our current study aimed to investigate the determinants of dementia among the oldest old using longitudinal data from a representative sample covering both community-dwelling and institutionalized individuals.

METHODS/DESIGN

Longitudinal representative data were taken from the "Survey on quality of life and subjective well-being of the very old in North Rhine-Westphalia (NRW80+)" that surveyed community-dwelling and institutionalized individuals aged 80 years and above (n = 1,296 observations in the analytic sample), living in North Rhine-Westphalia (most populous state of Germany). The established DemTect was used to measure cognitive impairment (i.e., probable dementia). A logistic random effects model was used to examine the determinants of probable dementia.

RESULTS

The mean age was 86.3 years (SD: 4.2 years). Multiple logistic regressions revealed that a higher likelihood of probable dementia was positively associated with lower education (e.g., low education compared to medium education: OR: 3.31 [95% CI: 1.10-9.98]), a smaller network size (OR: 0.87 [95% CI: 0.79-0.96]), lower health literacy (OR: 0.29 [95% CI: 0.14-0.60]), and higher functional impairment (OR: 13.45 [3.86-46.92]), whereas it was not significantly associated with sex, age, marital status, loneliness, and depressive symptoms in the total sample. Regressions stratified by sex were also reported.

DISCUSSION

Our study identified factors associated with dementia among the oldest old. This study extends current knowledge by using data from the oldest old; and by presenting findings based on longitudinal, representative data (also including individuals residing in institutionalized settings).

CONCLUSIONS

Efforts to increase, among other things, formal education, network size, and health literacy may be fruitful in postponing dementia, particularly among older women. Developing health literacy programs, for example, may be beneficial to reduce the burden associated with dementia.

Cognitive performance's critical role in the progression from educational attainment to moderate to vigorous physical activity: insights from a Mendelian randomization study

Introduction

In individuals with high educational levels, moderate to vigorous physical activity (MVPA) is often elevated, yet the causal direction and the role of cognitive performance in this association remain ambiguous. Herein, Mendel randomization (MR) was employed to measure the causal relationship between education, cognitive performance, and moderate to vigorous physical activity. The purpose of this study was to analyze the causal effects of educational attainment on moderate-to-vigorous physical activity (MVPA) levels and to explore potential mediating factors.

Methods

Two-sample univariate MR analysis was conducted to assess the overall effect of education on moderate to severe physical activity. Besides, a two-step MR analysis was carried out to evaluate the mediating effect of cognitive performance on the impact of education on moderate to severe physical activity. Individuals included were exclusively of European ancestry, with data gathered from extensive genome-wide association studies (GWAS) on education (n = 470,941), cognitive performance (n = 257,841), and moderate-to-vigorous physical activity (MVPA) (n = 377,234). Educational attainment was measured by college graduation status. Cognitive performance encompasses not only psycho-motor speed, memory, and abstract reasoning abilities but also knowledge and skills acquired in professional domains. MVPA is defined as any physical activity that produces a metabolic equivalent (MET) of ≥3.0.

Results

The positive two-sample MR analysis showed that education level had a significant protective effect on MVPA deficiency (β = -0.276, 95% CI = -0.354 to -0.199, p = 2.866 × 10-12). However, the reverse two-sample MR analysis showed that MVPA had no significant causal relationship with education level (p = 0.165). Subsequently, the two-step MR analysis indicated that the potential causal protective effect of education on the risk of MVPA deficiency was mostly mediated by cognitive performance (mediating effect β = -0.235, 95% CI = -0.434 to -0.036, and the intermediary ratio was 85.061%).

Discussion

Cognitive performance holds considerable significance in the relationship between education level and MVPA. Consequently, the intervention of cognitive performance may greatly improve the risk of physical inactivity caused by education, thereby promoting individual health.

Exploration of the Hungarian Version of Test Your Memory in General Practice: A Cross-Sectional Correlational Study of a Convenience Sample of Middle-Aged and Older Adults

BACKGROUND

Dementia is a significant health issue worldwide. Mild cognitive impairment (MCI) can transform into dementia over time. General practitioners (GPs) may be the first to notice the cognitive deficit; therefore, it is crucial for them to have access to a screening test that can be administered quickly and efficiently. We explored the Hungarian version of the Test Your Memory self-administered dementia screening test in general practice for the early detection of dementia and cognitive impairment.

METHODS

In the four Hungarian cities with medical universities, 368 patients over the age of 50 attending GPs filled out the questionnaire within the framework of our cross-sectional study.

RESULTS

The total scores of the test showed a significant correlation with education and type of occupation and a significant negative correlation with age. The results of this research showed that the clock drawing and recall subtest scores deteriorate at the earliest age.

CONCLUSION

The test can be filled out in a GP's office easily and two of its subtests can raise the possibility that patients may need further assessment, especially if they have symptoms, at an earlier age than the other subtests.

General cognitive ability in high school, attained education, occupational complexity, and dementia risk

INTRODUCTION

We address the extent to which adolescent cognition predicts dementia risk in later life, mediated by educational attainment and occupational complexity.

METHODS

Using data from Project Talent Aging Study (PTAS), we fitted two structural equation models to test whether adolescent cognition predicts cognitive impairment (CI) and Ascertain Dementia 8 (AD8) status simultaneously (NCognitive Assessment = 2477) and AD8 alone (NQuestionnaire = 6491) 60 years later, mediated by education and occupational complexity. Co-twin control analysis examined 82 discordant pairs for CI/AD8.

RESULTS

Education partially mediated the effect of adolescent cognition on CI in the cognitive assessment aample and AD8 in the questionnaire sample (Ps < 0.001). Within twin pairs, differences in adolescent cognition were small, but intrapair differences in education predicted CI status.

DISCUSSION

Adolescent cognition predicted dementia risk 60 years later, partially mediated through education. Educational attainment, but not occupational complexity, contributes to CI risk beyond its role as a mediator of adolescent cognition, further supported by the co-twin analyses.

HIGHLIGHTS

Project Talent Aging Study follows enrollees from high school for nearly 60 years. General cognitive ability in high school predicts later-life cognitive impairment. Low education is a risk partially due to its association with cognitive ability.

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.

A Potential Role for the Ketogenic Diet in Alzheimer's Disease Treatment: Exploring Pre-Clinical and Clinical Evidence

Given the remarkable progress in global health and overall quality of life, the significant rise in life expectancy has become intertwined with the surging occurrence of neurodegenerative disorders (NDs). This emerging trend is poised to pose a substantial challenge to the fields of medicine and public health in the years ahead. In this context, Alzheimer's disease (AD) is regarded as an ND that causes recent memory loss, motor impairment and cognitive deficits. AD is the most common cause of dementia in the elderly and its development is linked to multifactorial interactions between the environment, genetics, aging and lifestyle. The pathological hallmarks in AD are the accumulation of β-amyloid peptide (Aβ), the hyperphosphorylation of tau protein, neurotoxic events and impaired glucose metabolism. Due to pharmacological limitations and in view of the prevailing glycemic hypometabolism, the ketogenic diet (KD) emerges as a promising non-pharmacological possibility for managing AD, an approach that has already demonstrated efficacy in addressing other disorders, notably epilepsy. The KD consists of a food regimen in which carbohydrate intake is discouraged at the expense of increased lipid consumption, inducing metabolic ketosis whereby the main source of energy becomes ketone bodies instead of glucose. Thus, under these dietary conditions, neuronal death via lack of energy would be decreased, inasmuch as the metabolism of lipids is not impaired in AD. In this way, the clinical picture of patients with AD would potentially improve via the slowing down of symptoms and delaying of the progression of the disease. Hence, this review aims to explore the rationale behind utilizing the KD in AD treatment while emphasizing the metabolic interplay between the KD and the improvement of AD indicators, drawing insights from both preclinical and clinical investigations. Via a comprehensive examination of the studies detailed in this review, it is evident that the KD emerges as a promising alternative for managing AD. Moreover, its efficacy is notably enhanced when dietary composition is modified, thereby opening up innovative avenues for decreasing the progression of AD.

Risk factors of cognitive impairment: Impact of decline in oral function

Cognitive impairment and subsequent dementia are the major causes of disability and need for nursing care among older people in worldwide. The purpose is to review well-known risk factors for cognitive impairment and dementia, focusing on the relationship between decline in oral function and current prevention strategies. Various non-modifiable and modifiable risk factors are related to cognitive impairment. Effects of oral function to cognitive impairment is not yet well recognized in the medical community, although masticatory function, occlusal force, and number of teeth have been reported to be related to cognitive function. Furthermore, occlusal force rather than number of teeth was significantly related to the early stages of cognitive impairment, and that a decline in occlusal force seemed to lead to cognitive impairment directly and indirectly through dietary intake. This relationship was significant only for occlusal force, which may be associated with the early stages of cognitive decline. Nutritional change caused by reduced masticatory function is suggested as a possible explanation. Therefore, rehabilitation or maintenance of oral function should be sought to prevent cognitive impairment.

Technology for activity participation in older people with mild cognitive impairment or dementia: expert perspectives and a scoping review

PURPOSE

This two-phased study aimed to collate, summarize and characterize - through the lens of an occupation-based, person-centred framework - ongoing research and practice featuring activity participation-supportive digital health technology (DHT) for direct use by older persons with mild cognitive impairment or Alzheimer's disease and related dementias (PwMCI/ADRD).

MATERIALS AND METHODS

Phase 1: Using scoping review procedures, PubMed, MEDLINE and PsycInfo were searched to identify primary research studies. Phase 2: Semi-structured interviews were completed with MCI/ADRD expert stakeholders identified through publicly available biographies and snowball referral. Thematic analysis was used to identify, synthesize and cross-compare emergent themes from both data sources that were subsequently organized into core facets of the Human Activity Assistive Technology (HAAT) model.

RESULTS

The scoping review resulted in 28 studies, which were primarily feasibility work with small sample sizes. Interviewed experts (N = 17) had 4+ years of MCI/ADRD experience, came from a variety of settings, and held myriad roles. Real world and research-based use of DHTs held some commonalities, particularly around support for social participation and instrumental activities of daily engagement. No DHT for sleep or work/volunteerism were noted in either phase. People with milder MCI/ADRD conditions were most often targeted users. Soft technology strategies facilitating implementation centred on product design (e.g., prompting software, customisability, multimedia/multisensory experiences), instructional methods and technology partner involvement.

CONCLUSIONS

This study demonstrates that although DHT supportive of activity participation is being studied and integrated into the lives of PwMCI/ADRD, there are still key opportunities for growth to meet the needs of diverse MCI/ADRD end users.Implications for rehabilitationMainstream digital health technologies (DHTs) are being utilized by persons with mild cognitive impairment and Alzheimer's disease and related dementias (PwMCI/ADRD) in everyday life, in limited capacities, to support social participation, leisure, health management and instrumental activities of daily living (IADL).Innovative research-based technologies to be used directly by PwMCI/ADRD are under development, particularly to facilitate management of ADL, social participation and IADL in persons with mild-to-moderate forms of cognitive impairment.Soft technology strategies to support technology implementation with MCI/ADRD target users include close attention to design of the technology (e.g., customisability, sensory stimulators and prompting features), instructional strategies that promote learning and motivation and involvement of technology partners to facilitate engagement with the technology.Future studies will require more robust research designs with transparent reports of participant characteristics and facilitative instructional methods to expand DHT's potential to account for and better meet the needs of diverse MCI/ADRD communities in real-world contexts.

Disability Among Older Adults in South-Eastern Nigeria

Disability is a common reason for the loss of independence. There is a dearth of data on older adults with disability in south-eastern Nigeria. Using a multistage sampling technique and disability indexes, we assessed 816 persons aged 65 years and above living with a disability. While respondents' experiences of abuse and property inheritance differ by gender, they have poor health status. Elevated risks of disability were associated with gender, increased age, education, smoking, alcohol use, and engagement in physical exercise. Findings suggest urgency in formulating and implementing ageing welfare policy in this African community undergoing demographic and social changes. While this is underway, we recommend a massive health promotion among older adults in this community. We also suggest the integration of courses on ageing in schools' curriculum since ageing is a life course phenomenon. This in the long run would provide ageing-friendly education that averts old age's deleterious effects.

Links between early-life contextual factors and later-life cognition and the role of educational attainment

OBJECTIVE

Educational attainment is a well-documented predictor of later-life cognition, but less is known about upstream contextual factors. This study aimed to identify which early-life contextual factors uniquely predict later-life global cognition and whether educational attainment mediates these relationships.

METHOD

Participants were drawn from the Michigan Cognitive Aging Project (N = 485; Mage = 63.51; SDage = 3.13; 50% non-Hispanic Black). Early-life exposures included U.S. region of elementary school (Midwest, South, Northeast), average parental education, household composition (number of adults (1, 2, 3+), number of children), school racial demographics (predominantly White, predominantly Black, diverse), self-reported educational quality, and school type (public/private). Later-life global cognition was operationalized with a factor score derived from a comprehensive neuropsychological battery. Sequential mediation models controlling for sociodemographics estimated total, direct, and indirect effects of early-life contextual factors on cognition through educational attainment (years).

RESULTS

Higher educational quality, higher parental education, and attending a private school were each associated with better cognition; attending a predominantly Black or diverse school and reporting three or more adults in the household were associated with lower cognition. After accounting for educational attainment, associations remained for educational quality, school type, and reporting three or more adults in the household. Indirect effects through educational attainment were observed for school region, educational quality, school racial demographics, and parental education.

CONCLUSIONS

School factors appear to consistently predict later-life cognition more than household factors, highlighting the potential long-term benefits of school-level interventions for cognitive aging. Future research should consider additional mediators beyond educational attainment such as neighborhood resources and childhood adversity.

Modifiable cardiovascular risk factors and genetics for targeted prevention of dementia

Dementia is a major global challenge for health and social care in the 21st century. A third of individuals >65 years of age die with dementia, and worldwide incidence numbers are projected to be higher than 150 million by 2050. Dementia is, however, not an inevitable consequence of old age; 40% of dementia may theoretically be preventable. Alzheimer's disease (AD) accounts for approximately two-thirds of dementia cases and the major pathological hallmark of AD is accumulation of amyloid-β. Nevertheless, the exact pathological mechanisms of AD remain unknown. Cardiovascular disease and dementia share several risk factors and dementia often coexists with cerebrovascular disease. In a public health perspective, prevention is crucial, and it is suggested that a 10% reduction in prevalence of cardiovascular risk factors could prevent more than nine million dementia cases worldwide by 2050. Yet this assumes causality between cardiovascular risk factors and dementia and adherence to the interventions over decades for a large number of individuals. Using genome-wide association studies, the entire genome can be scanned for disease/trait associated loci in a hypothesis-free manner, and the compiled genetic information is not only useful for pinpointing novel pathogenic pathways but also for risk assessments. This enables identification of individuals at high risk, who likely will benefit the most from a targeted intervention. Further optimization of the risk stratification can be done by adding cardiovascular risk factors. Additional studies are, however, highly needed to elucidate dementia pathogenesis and potential shared causal risk factors between cardiovascular disease and dementia.

Cognitive reserve and individual differences in brain tumour patients

The aim of the paper is to determine the effects of the cognitive reserve on brain tumour patients' cognitive functions and, specifically, if cognitive reserve helps patients cope with the negative effects of brain tumours on their cognitive functions. We retrospectively studied a large sample of around 700 patients, diagnosed with a brain tumour. Each received an MRI brain examination and performed a battery of tests measuring their cognitive abilities before they underwent neurosurgery. To account for the complexity of cognitive reserve, we construct our cognitive reserve proxy by combining three predictors of patients' cognitive performance, namely, patients' education, occupation, and the environment where they live. Our statistical analysis controls for the type, side, site, and size of the lesion, for fluid intelligence quotient, and for age and gender, in order to tease out the effect of cognitive reserve on each of these tests. Clinical neurological variables have the expected effects on cognitive functions. We find a robust positive effect of cognitive reserve on patients' cognitive performance. Moreover, we find that cognitive reserve modulates the effects of the volume of the lesion: the additional negative impact of an increase in the tumour size on patients' performance is less severe for patients with higher cognitive reserve. We also find substantial differences in these effects depending on the cerebral hemisphere where the lesion occurred and on the cognitive function considered. For several of these functions, the positive effect of cognitive reserve is stronger for patients with lesions in the left hemisphere than for patients whose lesions are in the right hemisphere. The development of prevention strategies and personalized rehabilitation interventions will benefit from our contribution to understanding the role of cognitive reserve, in addition to that of neurological variables, as one of the factors determining the patients' individual differences in cognitive performance caused by brain tumours.

Association between self-reported oral health and cognitive function among the community-dwelling elderly in Jinan, China: the mediating effect of life satisfaction

Background

Deterioration of self-reported oral health and decline in cognitive function are two main adverse health outcomes experienced by the older adults. Little evidence was found on the psychosocial mechanism between self-reported oral health and cognitive function. This study explores the association between self-reported oral health and cognitive function and examines the mediating effect of life satisfaction among the community-dwelling elderly in Jinan, China.

Methods

A total of 512 older individuals (60+) were included in the study. Cognitive function was assessed using the Chinese version of the Mini-Mental State Examination scale (MMSE), and self-reported oral health was measured using the Chinese version of the Geriatric Oral Health Assessment Index (GOHAI). Pearson correlation analysis was used to determine the relationship between self-reported oral health, life satisfaction, and cognitive function. Multivariate linear regression analysis was conducted to explore the possible effect of covariates. Structural equation modelling and Bootstrap analyses were conducted to verify the mediating role of life satisfaction.

Results

The mean MMSE score was 25.65 ± 4.42. Better self-reported oral health was significantly associated with a higher level of life satisfaction, and those with higher life satisfaction experienced better cognitive function. Age, educational level and source of living expenses were found to be cofounding variables. Life satisfaction partially mediated the effect of self-reported oral health on cognitive function (95% confidence interval [CI]: 0.010 to 0.075). The mediating effect of life satisfaction accounted for 24% of the total effect.

Conclusion

The level of cognitive function was relatively high. Self-reported oral health was positively associated with cognitive function, and the mediating effect of life satisfaction was proven to exist in the community-dwelling older individuals. Early screening for oral diseases and a greater focus on life satisfaction are recommended.

Effectiveness of Caregiver-Provided Individual Cognitive Interventions in Older Adults with Dementia

Background

In a society increasingly committed to promoting an active life in the community, new resources are needed to respond to the needs of citizens with Alzheimer's disease and other forms of dementia. The potential of several individual cognitive interventions to be provided by caregivers has been explored in the literature.

Objective

To synthesize the best available evidence on the effectiveness of caregiver-provided individual cognitive interventions in older adults with dementia.

Methods

Systematic review of experimental studies on individual cognitive interventions for older adults with dementia. An initial search of MEDLINE and CINAHL was undertaken. Another search for published and unpublished studies was performed on major healthcare-related online databases in March 2018 and updated in August 2022. This review considered studies that included older adults with dementia, aged 60 years and over. All studies that met the inclusion criteria were assessed for methodological quality using a JBI standardized critical appraisal checklist. Data were extracted using a JBI data extraction form for experimental studies.

Results

Eleven studies were included: eight randomized controlled trials and three quasi-experimental studies. Caregiver-provided individual cognitive interventions had several beneficial effects in cognitive domains, including memory, verbal fluency, attention, problem-solving, and autonomy in activities of daily living.

Conclusion

These interventions were associated with moderate improvements in cognitive performance and benefits in activities of daily living. The findings highlight the potential of caregiver-provided individual cognitive interventions for older adults with dementia.

Educational attainment, structural brain reserve and Alzheimer's disease: a Mendelian randomization analysis

Higher educational attainment is observationally associated with lower risk of Alzheimer's disease. However, the biological mechanisms underpinning this association remain unclear. The protective effect of education on Alzheimer's disease may be mediated via increased brain reserve. We used two-sample Mendelian randomization to explore putative causal relationships between educational attainment, structural brain reserve as proxied by MRI phenotypes and Alzheimer's disease. Summary statistics were obtained from genome-wide association studies of educational attainment (n = 1 131 881), late-onset Alzheimer's disease (35 274 cases, 59 163 controls) and 15 measures of grey or white matter macro- or micro-structure derived from structural or diffusion MRI (nmax = 33 211). We conducted univariable Mendelian randomization analyses to investigate bidirectional associations between (i) educational attainment and Alzheimer's disease; (ii) educational attainment and imaging-derived phenotypes; and (iii) imaging-derived phenotypes and Alzheimer's disease. Multivariable Mendelian randomization was used to assess whether brain structure phenotypes mediated the effect of education on Alzheimer's disease risk. Genetically proxied educational attainment was inversely associated with Alzheimer's disease (odds ratio per standard deviation increase in genetically predicted years of schooling = 0.70, 95% confidence interval 0.60, 0.80). There were positive associations between genetically predicted educational attainment and four cortical metrics (standard deviation units change in imaging phenotype per one standard deviation increase in genetically predicted years of schooling): surface area 0.30 (95% confidence interval 0.20, 0.40); volume 0.29 (95% confidence interval 0.20, 0.37); intrinsic curvature 0.18 (95% confidence interval 0.11, 0.25); local gyrification index 0.21 (95% confidence interval 0.11, 0.31)]; and inverse associations with cortical intracellular volume fraction [-0.09 (95% confidence interval -0.15, -0.03)] and white matter hyperintensities volume [-0.14 (95% confidence interval -0.23, -0.05)]. Genetically proxied levels of surface area, cortical volume and intrinsic curvature were positively associated with educational attainment [standard deviation units change in years of schooling per one standard deviation increase in respective genetically predicted imaging phenotype: 0.13 (95% confidence interval 0.10, 0.16); 0.15 (95% confidence interval 0.11, 0.19) and 0.12 (95% confidence interval 0.04, 0.19)]. We found no evidence of associations between genetically predicted imaging-derived phenotypes and Alzheimer's disease. The inverse association of genetically predicted educational attainment with Alzheimer's disease did not attenuate after adjusting for imaging-derived phenotypes in multivariable analyses. Our results provide support for a protective causal effect of educational attainment on Alzheimer's disease risk, as well as potential bidirectional causal relationships between education and brain macro- and micro-structure. However, we did not find evidence that these structural markers affect risk of Alzheimer's disease. The protective effect of education on Alzheimer's disease may be mediated via other measures of brain reserve not included in the present study, or by alternative mechanisms.

High school quality is associated with cognition 58 years later

We leveraged a unique school-based longitudinal cohort-the Project Talent Aging Study-to examine whether attending higher quality schools is associated with cognitive performance among older adults in the United States (mean age = 74.8). Participants (n = 2,289) completed telephone neurocognitive testing. Six indicators of high school quality, reported by principals at the time of schooling, were predictors of respondents' cognitive function 58 years later. To account for school-clustering, multilevel linear and logistic models were applied. We found that attending schools with a higher number of teachers with graduate training was the clearest predictor of later-life cognition, and school quality mattered especially for language abilities. Importantly, Black respondents (n = 239; 10.5 percentage) were disproportionately exposed to low quality high schools. Therefore, increased investment in schools, especially those that serve Black children, could be a powerful strategy to improve later life cognitive health among older adults in the United States.

State-Level Indicators of Childhood Educational Quality and Incident Dementia in Older Black and White Adults

Importance

Higher educational attainment is associated with reduced dementia risk, but the role of educational quality is understudied, presenting a major evidence gap, especially as it may contribute to racial inequities.

Objective

To evaluate the association between state-level educational quality during childhood and dementia risk.

Design, Setting, and Participants

This cohort study analyzed longitudinal data collected from January 1, 1997, through December 31, 2019 (23-year follow-up period). The sample comprised members of Kaiser Permanente Northern California (KPNC), a large integrated health care delivery system, who completed an optional survey during 1964-1972. Eligible individuals were US born; non-Hispanic Black or non-Hispanic White; aged 65 years or older as of January 1, 1996; were still alive; and did not have a dementia diagnosis or lapse in KPNC membership greater than 90 days between January 1 and December 31, 1996.

Exposures

Historical state-level administrative indicators of school quality (school term length, student-teacher ratio, and attendance rates) linked to participants using birth state and birth year (with a 6-year lag) and divided into tertiles using the pooled sample.

Main Outcomes and Measures

Dementia diagnoses from electronic health records between 1997 and 2019 were analyzed between March 1 and August 31, 2022. The associations of educational quality with incident dementia were estimated using Cox proportional hazards regression models.

Results

Among 21 450 KPNC members who participated in the optional survey, individuals born before availability of educational quality records (n = 87) and missing educational attainment (n = 585) were excluded. The final analytic sample was 20 778 individuals (56.5% women, 43.5% men; mean [SD] age, 74.7 [6.5] years; 18.8% Black; 81.2% White; 41.0% with less than high school education). Among Black individuals, 76.2% to 86.1% (vs 20.8%-23.3% of White individuals) attended schools in states in the lowest educational quality tertiles. Highest (vs lowest) educational quality tertiles were associated with lower dementia risk (student-teacher ratio: hazard ratio [HR], 0.88 [95% CI, 0.83-0.94]; attendance rates: HR, 0.80 [95% CI, 0.73-0.88]; term length: HR, 0.79 [95% CI, 0.73-0.86]). Effect estimates did not differ by race and were not attenuated by adjustment for educational attainment.

Conclusions and Relevance

In this cohort study, lower state-average educational quality was more common among Black individuals and associated with higher dementia risk. Differential investment in high-quality education due to structural racism may contribute to dementia disparities.

Nature, Nurture, and the Meaning of Educational Attainment: Differences by Sex and Socioeconomic Status

Estimated heritability of educational attainment (EA) varies widely, from 23% to 80%, with growing evidence suggesting the degree to which genetic variation contributes to individual differences in EA is highly dependent upon situational factors. We aimed to decompose EA into influences attributable to genetic propensity and to environmental context and their interplay, while considering influences of rearing household economic status (HES) and sex. We use the Project Talent Twin and Sibling Study, drawn from the population-representative cohort of high school students assessed in 1960 and followed through 2014, to ages 68-72. Data from 3552 twins and siblings from 1741 families were analyzed using multilevel regression and multiple group structural equation models. Individuals from less-advantaged backgrounds had lower EA and less variation. Genetic variance accounted for 51% of the total variance, but within women and men, 40% and 58% of the total variance respectively. Men had stable genetic variance on EA across all HES strata, whereas high HES women showed the same level of genetic influence as men, and lower HES women had constrained genetic influence on EA. Unexpectedly, middle HES women showed the largest constraints in genetic influence on EA. Shared family environment appears to make an outsized contribution to greater variability for women in this middle stratum and whether they pursue more EA. Implications are that without considering early life opportunity, genetic studies on education may mischaracterize sex differences because education reflects different degrees of genetic and environmental influences for women and men.

The Burden of Dementia Spectrum Disorders and Associated Comorbid and Demographic Features

Dementia spectrum disorders (DSDs) are a major cause of mortality and disability worldwide. DSDs encompass a large group of medical conditions that all ultimately lead to major functional and cognitive decline and disability. Demographic and comorbid conditions that are associated with DSDs have significant prognostic and preventive implications. In this article, we will discuss the global and regional burden of DSDs and cover key demographic and clinical conditions linked with DSDs. In the absence of disease-modifying treatments, the role of primary prevention has become more prominent. Implementation of preventive measures requires an understanding of predisposing and exacerbating factors.

Transcranial Direct Current Stimulation Intervention in Alzheimer's Disease and Its Follow-Up

BACKGROUND

Alzheimer's disease (AD) stands as the prevailing type of dementia, marked by gradual memory loss and cognitive decline. Transcranial direct current stimulation (tDCS) is a non-invasive method used to regulate cortical brain function and has been explored as a potential treatment for cognitive impairment.

OBJECTIVE

This study aimed to compare the effects of daily home-based active or sham tDCS on cognitive function in patients with early-stage AD and its follow-up after one month.

METHODS

The study involved a randomized, blinded, and controlled-placebo design, with 18 participants enrolled. The primary outcome measures were general cognitive function, immediate, and delayed recall, and executive function. Participants included in the study were randomly assigned to the anodal and sham tDCS groups. Participants were assessed before and after the intervention and one month after the end of treatment. The home-based intervention was applied for 5 consecutive days, daily.

RESULTS

The results showed a significant interaction between the active and sham groups; in particular, improvements in MMSE scores, immediate memory and delayed recall were observed at one-month follow-up in the active group.

CONCLUSIONS

The positive effects of tDCS on cognitive function in AD patients observed suggest that tDCS may induce long-term neuroplastic changes, leading to sustained improvements in cognitive abilities.

The Mediating Roles of Neurobiomarkers in the Relationship Between Education and Late-Life Cognition

BACKGROUND

The mediating roles of neuropathologies and neurovascular damage in the relationship between early-life education and later-life cognitive function are unknown.

OBJECTIVE

To examine whether Alzheimer's and neurovascular biomarkers mediate the relationships between education and cognitive functions.

METHODS

Data were from 537 adults aged 55-94 in the Alzheimer's Disease Neuroimaging Initiative 3. We tested whether the relationships between education (continuous, years) and cognitive function (memory, executive functioning, and language composites) were mediated by neuroimaging biomarkers (hippocampal volumes, cortical gray matter volumes, meta-temporal tau PET standard uptake value ratio, and white matter hyperintensity volumes). Models were adjusted for age, race, sex/gender, cardiovascular history, body mass index, depression, and Apolipoprotein E-ɛ4 status.

RESULTS

Hippocampal volumes and white matter hyperintensities partially mediated the relationships between education and cognitive function across all domains (6.43% to 15.72% mediated). The direct effects of education on each cognitive domain were strong and statistically significant.

CONCLUSIONS

Commonly measured neurobiomarkers only partially mediate the relationships between education and multi-domain cognitive function.

Could Country-Level Factors Explain Sex Differences in Dementia Incidence and Prevalence? A Systematic Review and Meta-Analysis

BACKGROUND

Despite rising interest in sex differences in dementia, it is unclear whether sex differences in dementia incidence and prevalence are apparent globally.

OBJECTIVE

We examine sex differences in incidence and prevalence of Any dementia, Alzheimer's disease (AD), and vascular dementia (VaD), and evaluate whether country-level indicators of gender inequality account for differences.

METHODS

Systematic review with meta-analysis was used to obtain estimates of incidence and prevalence of Any dementia, AD, and VaD using random effects meta-analysis, and population-based studies with clinical or validated dementia measures. Meta-regression was used to evaluate how country-specific factors of life expectancy, education, and gender differences in development, unemployment, and inequality indices influenced estimates.

RESULTS

We identified 205 eligible studies from 8,731 articles, representing 998,187 participants across 43 countries. There were no sex differences in the incidence of Any dementia, AD, or VaD, except in the 90+ age group (women higher). When examined by 5-year age bands, the only sex difference in prevalence of Any dementia was in the 85+ group and there was no sex difference in VaD. AD was more prevalent in women at most ages. Globally, the overall prevalence of dementia in adults 65 + was higher for women (80.22/1000, 95% CI 62.83-97.61) than men (54.86/1000, 95% CI 43.55-66.17). Meta-regression revealed that sex differences in Any dementia prevalence were associated with gender differences in life expectancy and in education.

CONCLUSION

Globally, there are no sex differences in age-specific dementia incidence, but prevalence of AD is higher in women. Country-level factors like life expectancy and gender differences in education may explain variability in sex differences.

Cognitive Performance and Diabetic Retinopathy: What Your Eyes Can Reveal About Your Brain

BACKGROUND

Diabetic retinopathy (DR) is a chronic diabetes complication. People with Type 2 Diabetes Mellitus (T2DM) have two times the risk for dementia, suggesting it is a new chronic diabetes complication.

OBJECTIVE

Evaluate the association of DR with cognitive performance in a T2DM population.

METHODS

Cross-sectional study with 400 T2DM adults from whom socio-demographic, clinical, laboratory data were collected, and screening test for depression symptoms (Patient Health Questionaire- 9 (PHQ-9)), Mini-Mental State Examination (MMSE), Semantic Verbal Fluency Test, Trail Making Test A and B, Word Memory test were performed. All cognitive test scores were converted into Global Cognition z-Score (GCS(z)). The association between GCS(z) < 0 with DR was performed using a multivariate binary logistic regression model adjusted for age ≥ 65 years, school years ≤ 6 years, DM duration ≥ 10 years, depression symptoms score > 9 at PHQ-9, arterial hypertension, physical activity, diabetic retinopathy, macular edema, and cardiovascular disease.

RESULTS

After exclusions, the 251 eligible patients were 56.6% female, with a mean age of 61.1 (±9.8) years, DM duration of 12.6 (±8.9) years, and 7.6 (±4.2) years of school education. DR prevalence was 46.5%. Multivariate Logistic Regression Model showed an association between DR and GCS(z) < 0, with odds ratio (CI95%) of 2.50 (1.18-5.34), adjusted for age, low education level, arterial hypertension and depression symptoms (OD and CI95% respectively: 5.46(2.42-12.34); 12.19 (5.62-26.46); 2.55 (0.88-7.39); 3.53 (1.55-8.07)).

CONCLUSION

In this T2DM population, having DR increased the chance for worse cognitive performance even when adjusted for age, low education level, presence of arterial hypertension, and depression symptoms.

Frequency and correlates of mild cognitive impairment and dementia among the oldest old - Evidence from the representative "Survey on quality of life and subjective well-being of the very old in North Rhine-Westphalia (NRW80+)"

OBJECTIVES

Since there is limited knowledge with regard to the frequency and correlates of mild cognitive impairment and dementia among the oldest old based on large representative data (including institutionalized individuals), our objective was to fill this research gap.

METHODS

For our study, data came from the representative "Survey on quality of life and subjective well-being of the very old in North Rhine-Westphalia (NRW80+)". This study included community-dwelling and institutionalized individuals aged 80 years and over (n = 1,173, mean age: 86 years) residing in the most populous state of Germany (North Rhine-Westphalia). The DemTect was used to quantify cognitive impairment (i.e., probable mild cognitive impairment and probable dementia).

RESULTS

Overall, 73.1% of the individuals were not cognitively impaired, 17.0% of the individuals had probable mild cognitive impairment and 9.9% of the individuals had probable dementia. Compared to individuals without cognitive impairment, individuals with probable mild cognitive impairment were more likely to be male, live in an institutionalized setting, have a lower educational level, have a smaller network size, and have lower functional abilities. Moreover, compared to individuals without cognitive impairment, individuals with probable dementia were more likely to be older, live in an institutionalized setting, have a lower educational level, have a smaller network size, not be multimorbid, and have lower functional abilities.

CONCLUSIONS

Our study identified several sociodemographic and health-related factors which are associated with probable mild cognitive impairment and probable dementia among the oldest old. This knowledge may help to address individuals at risk for mild cognitive impairment and dementia.

Cognitive after-effects and associated correlates among post-illness COVID-19 survivors: a cross-sectional study, Egypt

Background

COVID-19’s after-effects among survivors are of increased concern. The cognitive aftermath of COVID-19 virus infection was underrated. This study aimed to identify and compare the cognitive impairment (CI) and its correlates among COVID-19 survivors and control subjects. A total of 85 adults who survived COVID-19 virus infection and an equal number of control subjects (matched for age, sex, education, and socioeconomic level) were included in this study. They were recruited from Zagazig University Hospitals, Sharkia Province, Egypt. All subjects were interviewed utilizing a semistructured demographic and clinical checklist, the Montreal Cognitive Assessment (MoCA) test, and the Hospital Anxiety Depression Scale (HADS).

Results

More than half of COVID-19 survivors experienced CI (compared to only 8% of control subjects). Individuals who survived COVID-19 virus infection were more likely to have impairments in visuo-executive functions (OR: 0.3, 95% CI 0.2–0.5), attention (OR: 0.4, 95% CI 0.3–0.7), language (OR: 0.2, 95% CI 0.1–0.5), delayed recall (OR: 0.5, 95% CI 0.4–0.6), and total MoCA Scores (OR: 0.1, 95% CI 0.04–0.2). Among COVID-19 survivors, those who experienced CI were likely to be older (OR: 1.1, 95% CI 1.03–1.2), and of low-to-moderate education (OR: 4.9, 95% CI 1.6–15.1).

Conclusions

CI was prevalent among COVID-19 survivors. The visuo-executive functions, attention, language, and delayed recall were the most affected domains. Older age and lower educational level predicted CI in COVID-19 survivors.

Cognitive performance protects against Alzheimer's disease independently of educational attainment and intelligence

Mendelian-randomization (MR) studies using large-scale genome-wide association studies (GWAS) have identified causal association between educational attainment and Alzheimer's disease (AD). However, the underlying mechanisms are still required to be explored. Here, we conduct univariable and multivariable MR analyses using large-scale educational attainment, cognitive performance, intelligence and AD GWAS datasets. In stage 1, we found significant causal effects of educational attainment on cognitive performance (beta = 0.907, 95% confidence interval (CI): 0.884-0.930, P < 1.145E-299), and vice versa (beta = 0.571, 95% CI: 0.557-0.585, P < 1.145E-299). In stage 2, we found that both increase in educational attainment (odds ratio (OR) = 0.72, 95% CI: 0.66-0.78, P = 1.39E-14) and cognitive performance (OR = 0.69, 95% CI: 0.64-0.75, P = 1.78E-20) could reduce the risk of AD. In stage 3, we found that educational attainment may protect against AD dependently of cognitive performance (OR = 1.07, 95% CI: 0.90-1.28, P = 4.48E-01), and cognitive performance may protect against AD independently of educational attainment (OR = 0.69, 95% CI: 0.53-0.89, P = 5.00E-03). In stage 4, we found significant causal effects of cognitive performance on intelligence (beta = 0.907, 95% CI: 0.877-0.938, P < 1.145E-299), and vice versa (beta = 0.957, 95% CI: 0.937-0.978, P < 1.145E-299). In stage 5, we identified that cognitive performance may protect against AD independently of intelligence (OR = 0.74, 95% CI: 0.61-0.90, P = 2.00E-03), and intelligence may protect against AD dependently of cognitive performance (OR = 1.17, 95% CI: 0.40-3.43, P = 4.48E-01). Collectively, our univariable and multivariable MR analyses highlight the protective role of cognitive performance in AD independently of educational attainment and intelligence. In addition to the intelligence, we extend the mechanisms underlying the associations of educational attainment with AD.

Develop a diagnostic tool for dementia using machine learning and non-imaging features

Background

Early identification of Alzheimer’s disease or mild cognitive impairment can help guide direct prevention and supportive treatments, improve outcomes, and reduce medical costs. Existing advanced diagnostic tools are mostly based on neuroimaging and suffer from certain problems in cost, reliability, repeatability, accessibility, ease of use, and clinical integration. To address these problems, we developed, evaluated, and implemented an early diagnostic tool using machine learning and non-imaging factors.

Methods and results

A total of 654 participants aged 65 or older from the Nursing Home in Hangzhou, China were identified. Information collected from these patients includes dementia status and 70 demographic, cognitive, socioeconomic, and clinical features. Logistic regression, support vector machine (SVM), neural network, random forest, extreme gradient boosting (XGBoost), least absolute shrinkage and selection operator (LASSO), and best subset models were trained, tuned, and internally validated using a novel double cross validation algorithm and multiple evaluation metrics. The trained models were also compared and externally validated using a separate dataset with 1,100 participants from four communities in Zhejiang Province, China. The model with the best performance was then identified and implemented online with a friendly user interface. For the nursing dataset, the top three models are the neural network (AUROC = 0.9435), XGBoost (AUROC = 0.9398), and SVM with the polynomial kernel (AUROC = 0.9213). With the community dataset, the best three models are the random forest (AUROC = 0.9259), SVM with linear kernel (AUROC = 0.9282), and SVM with polynomial kernel (AUROC = 0.9213). The F1 scores and area under the precision-recall curve showed that the SVMs, neural network, and random forest were robust on the unbalanced community dataset. Overall the SVM with the polynomial kernel was found to be the best model. The LASSO and best subset models identified 17 features most relevant to dementia prediction, mostly from cognitive test results and socioeconomic characteristics.

Conclusion

Our non-imaging-based diagnostic tool can effectively predict dementia outcomes. The tool can be conveniently incorporated into clinical practice. Its online implementation allows zero barriers to its use, which enhances the disease’s diagnosis, improves the quality of care, and reduces costs.

Physical and Mental Activity, Disease Susceptibility, and Risk of Dementia: A Prospective Cohort Study Based on UK Biobank

BACKGROUND AND OBJECTIVES

The association between patterns of physical/mental activity and dementia and how it is affected by disease susceptibility remains unknown. We aimed to examine the association between patterns of physical and mental activity and dementia and whether it can be modified by disease susceptibility to dementia.

METHODS

In a prospective cohort study based on UK Biobank, 501,376 dementia-free participants were recruited in 2006-2010 and followed from 1 year after the recruitment date until the end of 2019 for ascertainment of dementia. Data on physical (i.e., physical activity at leisure time, housework-related activity, and transportation) and mental (i.e., intelligence, social contact, and use of electronic device) activity were collected using questionnaires at recruitment. Cox models were used to estimate the associations of physical and mental activity-related items, as well as major activity patterns identified by principal component analysis, with the risk of dementia, adjusted for multiple confounders. The modification role of disease susceptibility on such associations was assessed through stratified analyses by the polygenic risk score (PRS) of dementia generated based on summary statistics of independent genome-wide association studies, by the APOE genotype, and by the self-reported family history of dementia.

RESULTS

The mean age at recruitment was 56.53, and 45.60% of the participants were male. During a mean follow-up of 10.66 years, 5,185 dementia cases were identified. When analyzed separately, multiple studied items related to physical and mental activity showed significant associations with the risk of dementia. The pattern analyses revealed that a higher level of adherence to activity patterns related to frequent vigorous and other exercises (hazard ratio 0.65, 95% CI 0.59-0.71), housework-related activity (0.79, 0.72-0.85), and friend/family visit (0.85, 0.75-0.96) was associated with a lower risk of dementia. We obtained comparable results for vascular dementia and Alzheimer disease as well as in the stratified analyses by the PRS for dementia, APOE genotype, or family history of dementia.

DISCUSSION

Activity patterns more adherent to frequent vigorous and other exercises, housework-related activity, and friend/family visit were associated with a reduced risk of multiple types of dementia. Such associations are independent of disease susceptibility, highlighting the potential of these physical and mental activity patterns, as effective interventions, in the primary prevention of dementia.

Relationships between educational attainment, hypertension, and amyloid negative subcortical vascular dementia: The brain-battering hypothesis

Purpose

Many epidemiological studies suggest that lower education levels and vascular risk factors increase the likelihood of developing Alzheimer's disease dementia (ADD) and subcortical vascular dementia (SVaD). However, whether the brain-battering hypothesis can explain the relationship between education levels and the clinical diagnosis of dementia remains controversial. The objective of this study was to investigate whether vascular risk factors mediate the association between education level and the diagnosis of amyloid-beta positive (Aβ+) ADD and amyloid-beta negative (Aβ-) SVaD.

Methods

We analyzed 376 participants with Aβ normal cognition (Aβ- NC), 481 with Aβ+ ADD, and 102 with Aβ- SVaD. To investigate the association of education level and vascular risk factors with these diagnoses, multivariable logistic regression analysis was used, with age, sex, and APOE ε4 carrier status used as covariates. Path analysis was performed to investigate the mediation effects of hypertension on the diagnosis of Aβ- SVaD.

Results

The Aβ- SVaD group (7.9 ± 5.1 years) had lower education levels than did the Aβ- NC (11.8 ± 4.8 years) and Aβ+ ADD (11.2 ± 4.9 years) groups. The frequencies of hypertension and diabetes mellitus were higher in the Aβ- SVaD group (78.4 and 32.4%, respectively) than in the Aβ- NC (44.4 and 20.8%) and Aβ+ ADD (41.8 and 15.8%, respectively) groups. Increased education level was associated with a lower risk of Aβ- SVaD [odds ratio (OR) 0.866, 95% confidence interval (CI), 0.824–0.911], but not Aβ+ ADD (OR 0.971, 95% CI 0.940–1.003). The frequency of hypertension was associated with a higher risk of developing Aβ- SVaD (OR 3.373, 95% CI, 1.908–5.961), but not Aβ+ ADD (OR 0.884, 95% CI, 0.653–1.196). In the path analysis, the presence of hypertension partially mediated the association between education level and the diagnosis of Aβ- SVaD.

Conclusion

Our findings revealed that education level might influence the development of Aβ- SVaD through the brain-battering hypothesis. Furthermore, our findings suggest that suitable strategies, such as educational attainment and prevention of hypertension, are needed for the prevention of Aβ- SVaD.

Social determinants and lifestyle factors for brain health: implications for risk reduction of cognitive decline and dementia

Substantial evidence indicates a huge potential for risk reduction of cognitive decline and dementia based on modifiable health and lifestyle factors. To maximize the chances for risk reduction, it is useful to investigate associations of social determinants and lifestyle for brain health. We computed the "LIfestyle for BRAin health" (LIBRA) score for baseline participants of the Leipzig Research Centre for Civilization Diseases (LIFE) Adult Study, a population-based urban cohort in Germany. LIBRA predicts dementia in midlife and early late life populations, comprising 12 modifiable risk factors (heart disease, kidney disease, diabetes, obesity, hypertension, hypercholesterolemia, alcohol consumption, smoking, physical inactivity, diet, depression, cognitive inactivity). Associations of social determinants (living situation, marital status, social isolation, education, net equivalence income, occupational status, socioeconomic status/SES, employment) with LIBRA were inspected using age- and sex-adjusted multivariable linear regression analysis. Z-standardization and sampling weights were applied. Participants (n = 6203) were M = 57.4 (SD = 10.6, range 40-79) years old and without dementia, 53.0% were women. Except for marital status, all considered social determinants were significantly associated with LIBRA. Beta coefficients for the association with higher LIBRA scores were most pronounced for low SES (β = 0.80, 95% CI [0.72-0.88]; p < 0.001) and middle SES (β = 0.55, 95% CI [0.47-0.62]; p < 0.001). Social determinants, particularly socioeconomic factors, are associated with lifestyle for brain health, and should thus be addressed in risk reduction strategies for cognitive decline and dementia. A social-ecological public health perspective on risk reduction might be more effective and equitable than focusing on individual lifestyle behaviors alone.

The relationship of acute delirium with cognitive and psychiatric symptoms after stroke: a longitudinal study

Objective

Delirium, a common complication after stroke, is often overlooked, and long-term consequences are poorly understood. This study aims to explore whether delirium in the acute phase of stroke predicts cognitive and psychiatric symptoms three, 18 and 36 months later.

Method

As part of the Norwegian Cognitive Impairment After Stroke Study (Nor-COAST), 139 hospitalized stroke patients (49% women, mean (SD) age: 71.4 (13.4) years; mean (SD) National Institutes of Health Stroke Scale (NIHSS) 3.0 (4.0)) were screened for delirium with the Confusion Assessment Method (CAM). Global cognition was measured with the Montreal Cognitive Assessment (MoCA), while psychiatric symptoms were measured using the Hospital Anxiety and Depression Scale (HADS) and the Neuropsychiatric Inventory-Questionnaire (NPI-Q). Data was analyzed using mixed-model linear regression, adjusting for age, gender, education, NIHSS score at baseline and premorbid dementia.

Results

Thirteen patients met the criteria for delirium. Patients with delirium had lower MoCA scores compared to non-delirious patients, with the largest between-group difference found at 18 months (Mean (SE): 20.8 (1.4) versus (25.1 (0.4)). Delirium was associated with higher NPI-Q scores at 3 months (Mean (SE): 2.4 (0.6) versus 0.8 (0.1)), and higher HADS anxiety scores at 18 and 36 months, with the largest difference found at 36 months (Mean (SE): 6.2 (1.3) versus 2.2 (0.3)).

Conclusions

Suffering a delirium in the acute phase of stroke predicted more cognitive and psychiatric symptoms at follow-up, compared to non-delirious patients. Preventing and treating delirium may be important for decreasing the burden of post-stroke disability.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02756-5.

Effect of Sleep Disturbance on Cognitive Function in Elderly Individuals: A Prospective Cohort Study

Many epidemiologic and clinical studies have shown significant links between the degree of sleep disturbance and severity of impairment of selective cognitive functions, including the risk of neurodegenerative diseases. However, the sleep parameters that affect cognitive function in old age are unclear. Therefore, we investigated the association between sleep parameters and cognitive function in older patients. Patients aged above 65 years who complained of sleep-disordered breathing were enrolled consecutively. The Mini-Mental-State Examination tool was used to evaluate cognitive function. Eighty patients (normal cognitive function, n = 32 and cognitive impairment, n = 42) were included in this study. Multiple linear regression and binary logistic regression analyses were performed to explain the relationship between sleep parameters and cognitive function. We found that the body mass index (BMI) was significantly lower in the cognitive impairment group than in the normal cognitive function group. Additionally, the cognitive impairment group showed significantly decreased sleep efficiency and an increased apnea index compared with normal subjects. Moreover, lower BMI, reduced sleep efficiency, and high frequency of apnea events during sleep were associated with an increased risk of cognitive impairment.

Characteristics of people living with undiagnosed dementia: findings from the CFAS Wales study

Background

Many people living with dementia remain undiagnosed, with diagnosis usually occurring long after signs and symptoms are present. A timely diagnosis is important for the wellbeing of the person living with dementia and the family, allowing them to plan and have access to support services sooner. The aim of this study was to identify demographic characteristics and neuropsychiatric symptoms associated with being undiagnosed, which may help clinicians be more aware of signs that could be indicative of early-stage or undetected dementia.

Methods

This cross-sectional study uses data from waves 1 and 2 (two years apart) of the Cognitive Function and Ageing Studies Wales (CFAS Wales). CFAS Wales participants were included who had a study assessment of dementia, as determined by the Automated Geriatric Examination for Computer Assisted Taxonomy (AGECAT) algorithm and by expert assessment, and who had had their primary care records checked for a clinical diagnosis of dementia. We identified 19 people with a diagnosis of dementia and 105 people living with undiagnosed dementia, and explored demographic characteristics and the presence or absence of a range of neuropsychiatric symptoms in the undiagnosed population using logistic regression.

Results

Findings suggest that people living with dementia who have better cognition, have more years of education, or live in more deprived areas are less likely to have a diagnosis. In terms of neuropsychiatric symptoms, depression and sleep problems were associated with being undiagnosed. Apathy was common across all people living with dementia, but those with a diagnosis were more likely to have severe apathy.

Conclusions

This study has clinical practice implications as the findings may help clinicians be more aware of characteristics and symptoms of people who are undiagnosed or who are at greater risk of remaining undiagnosed, enabling them to be more vigilant in picking up signs of dementia at an earlier stage.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-03086-4.

Post-Operative Cognitive Impairment: A Cognitive Epidemiology Perspective

Cognitive epidemiology investigates cognitive predictors of health and disease outcomes. Post-operative cognitive impairment is a common complication of surgery but has been neglected as a health outcome in cognitive epidemiology research. This is despite the fact that knowledge of cognitive predictors of post-operative cognitive impairment can be utilized for risk stratification, informed decision-making (in elective surgery), and personalized care of patients during the postoperative period. In this narrative review, the current literature on cognitive predictors of post-operative cognitive impairment and gaps therein are summarized.

The Prevalence of Amnestic and Non-Amnestic Mild Cognitive Impairment and Its Association with Different Lifestyle Factors in a South Italian Elderly Population

Mild Cognitive Impairment (MCI) is a transition stage between normal aging and dementia and can be useful to monitor the cognitive status of people at risk of dementias. Our aims were to investigate the prevalence of amnestic and non-amnestic MCI in a South Italian elderly population, and to identify socio-demographic, clinical and lifestyle factors associated with MCI. A cross-sectional retrospective population study on 839 community-dwelling participants over 60 years of age was carried out. Elderly people were administered a brief neuropsychological screening to identify their cognitive and functional status, and a questionnaire to investigate several socio-demographic, clinical, and lifestyle factors. Prevalence estimate for MCI was 12.0% (95% CI: 10.0–14.5%), for amnestic MCI was 7.4% (95% CI: 5.8–9.4%), and for non-amnestic MCI was 4.6% (95% CI: 3.4–6.4%), for people older than 60 years of age. Logistic regression models, corrected for age, sex, and education, revealed a significant association of MCI with the following factors: age, education, intellectual activities, and topographical disorientation. On the other hand, education, clinical factors (e.g., depression level and perceived physical pain), lifestyle factors (e.g., smoking, alcohol, and leisure/productive activities), dietary habits, quality of life, and self-reported topographical disorientation were non-significantly associated with MCI. Prevalence estimates and the association of MCI and its subtypes with risk and protective factors were discussed in comparison with the most recent systematic reviews and meta-analyses.

Education, Occupational Complexity, and Incident Dementia: A COSMIC Collaborative Cohort Study

BACKGROUND

Education and occupational complexity are main sources of mental engagement during early life and adulthood respectively, but research findings are not conclusive regarding protective effects of these factors against late-life dementia.

OBJECTIVE

This project aimed to examine the unique contributions of education and occupational complexity to incident dementia, and to assess the mediating effects of occupational complexity on the association between education and dementia across diverse cohorts.

METHOD

We used data from 10,195 participants (median baseline age = 74.1, range = 58∼103), representing 9 international datasets from 6 countries over 4 continents. Using a coordinated analysis approach, the accelerated failure time model was applied to each dataset, followed by meta-analysis. In addition, causal mediation analyses were performed.

RESULT

The meta-analytic results indicated that both education and occupational complexity were independently associated with increased dementia-free survival time, with 28%of the effect of education mediated by occupational complexity. There was evidence of threshold effects for education, with increased dementia-free survival time associated with 'high school completion' or 'above high school' compared to 'middle school completion or below'.

CONCLUSION

Using datasets from a wide range of geographical regions, we found that both early life education and adulthood occupational complexity were independently predictive of dementia. Education and occupational experiences occur during early life and adulthood respectively, and dementia prevention efforts could thus be made at different stages of the life course.

Association between Late-Onset Ménière's Disease and the Risk of Incident All-Cause Dementia

Studies reported an association between impaired hearing and vestibular function with the risk of dementia. This study investigated the association between Ménière’s disease (MD) and the risk of dementia using a nationwide cohort sample of data obtained from the South Korea National Health Insurance Service. The MD group (n = 496) included patients aged over 55 years and diagnosed between 2003 and 2006. The comparison group was selected using propensity score matching (n = 1984). Cox proportional hazards regression models were used to calculate incidence and hazard ratios for dementia events. The incidence of dementia was 14.3 per 1000 person–years in the MD group. After adjustment for certain variables, the incidence of dementia was higher in the MD group than in the comparison group (adjusted hazard ratio (HR) = 1.57, 95% confidence interval = 1.17–2.12). Subgroup analysis showed a significantly increased adjusted HR for developing Alzheimer’s disease (1.69, 95% confidence interval = 1.20–2.37) and vascular dementia (1.99, 95% confidence interval = 1.10–3.57) in the MD group. Patients with dementia experienced a higher frequency of MD episodes than those without dementia. Our findings suggest that late-onset MD is associated with an increased incidence of all-cause dementia, and it might be used as a basis for an earlier diagnosis of dementia.

Serum Glycoproteomics and Identification of Potential Mechanisms Underlying Alzheimer’s Disease

Objectives. This study compares glycoproteomes in Thai Alzheimer’s disease (AD) patients with those of cognitively normal individuals. Methods. Study participants included outpatients with clinically diagnosed AD ( $N=136$ ) and healthy controls without cognitive impairment ( $N=183$ ). Blood samples were collected from all participants for biochemical analysis and for $\text{Apolipoprotein}\text{E}$ (APOE) genotyping by real-time TaqMan PCR assays. Comparative serum glycoproteomic profiling by liquid chromatography-tandem mass spectrometry was then performed to identify differentially abundant proteins with functional relevance. Results. Statistical differences in age, educational level, and APOE ɛ3/ɛ4 and ɛ4/ɛ4 haplotype frequencies were found between the AD and control groups. The frequency of the APOE ɛ4 allele was significantly higher in the AD group than in the control group. In total, 871 glycoproteins were identified, including 266 and 259 unique proteins in control and AD groups, respectively. There were 49 and 297 upregulated and downregulated glycoproteins, respectively, in AD samples compared with the controls. Unique AD glycoproteins were associated with numerous pathways, including Alzheimer’s disease-presenilin pathway (16.6%), inflammation pathway mediated by chemokine and cytokine signaling (9.2%), Wnt signaling pathway (8.2%), and apoptosis signaling pathway (6.7%). Conclusion. Functions and pathways associated with protein-protein interactions were identified in AD. Significant changes in these proteins can indicate the molecular mechanisms involved in the pathogenesis of AD, and they have the potential to serve as AD biomarkers. Such findings could allow us to better understand AD pathology.

The role of education and income for cognitive functioning in old age: A cross-country comparison

OBJECTIVES

Previous studies have shown that higher education promotes cognitive health. This effect, however, is embedded in the living conditions of a particular country. Since it is not clear to what extent the country and its specific living standards are necessary preconditions for the observed effect, we investigated whether the impact of education and income on cognitive functioning differs between countries.

METHODS

Analyses were based on harmonized data from the World Health Organization's multi-country Study on global AGEing and adult health, the Health and Retirement Study, and the Survey of Health, Ageing and Retirement in Europe of over 85,000 individuals aged 50 years and older. Analyses were conducted via multivariate regression analyses and structural equation modeling adjusted for age, gender, marital status, health status, and depression.

RESULTS

The effect of education was twice as large as the effect of income on cognitive functioning and indirectly moderated the effect of income on cognitive functioning. The effect sizes varied strongly between countries. The country's gross domestic product per capita seems to influence cognitive functioning.

CONCLUSIONS

Our findings indicate that education has a dominant effect on cognitive functioning in people aged 50 years and older, which might even offset the adverse implications of living with low income on cognitive health. Therefore, expanding efforts to achieve universal education are essential to mitigate health disparities due to low income and early life disadvantages, including chances for good cognitive functioning over the life-span.

Bilingualism as a protective factor in aphasia

BACKGROUND

Bilingualism may affect the profile of cognitive disturbances associated with stroke. Its impact on aphasia severity, however, is in need of substantiation.

AIMS

To determine the relationship between bilingualism and vascular aphasia severity.

METHODS

This is an observational cross-sectional study conducted on people with post-stroke aphasia. Our sample included 155 monolingual and 53 bilingual vascular aphasia patients. They were selected in a neurological hospital in Kolkata (West Bengal, India).

RESULTS

The Bengali version of Western Aphasia Battery (BWAB) was used in this study. Aphasia severity was compared between monolingual and bilingual participants. The overall difference in the mean aphasia quotient (AQ) between bilingual and monolingual participants was statistically significant (p = 0.009). It was also found that in bilingual participants, aphasia was less severe in certain subgroups, namely: higher lesion volume, male gender, and sub-cortical stroke, while in none of the subgroups a monolingual advantage was documented.

CONCLUSION

Current results suggest that bilingualism represents a protective factor in vascular aphasia; this effect is observed particularly in some aphasia subgroups.

Future life expectancy with disability among elderly Chinese individuals: a forecast based on trends in stroke and dementia

OBJECTIVES

This study aims to predict the life expectancy with disability (LED) of the elderly in China from 2010 to 2030 based on trends in stroke and dementia.

STUDY DESIGN

This was a prospective cohort study.

METHODS

Data for 28,667 eligible individuals aged 65+ years were derived from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) from 2002 to 2014. A discrete-time probabilistic Markov model was constructed with nine different health states characterized by the presence or absence of stroke, dementia, disability, or death. Binomial logistic regression was used to estimate the probability of state transition every 3 years based on the survey interval in the CLHLS. The number of disabled individuals was predicted in 2030 using Chinese population data from World Population Prospects 2019 and trends in the incidence and mortality for stroke and dementia as recorded in the CLHLS. A multistate life table was used to predict LED in 2030.

RESULTS

It is predicted that disability in those aged 65+ years in China will increase from 11.4 million in 2010 to 34.8 million in 2030. Cases associated with stroke and dementia are predicted to increase by 297.9% and 167.8%, respectively, for the 65-79 years age group, and by 402.1% and 247.0%, respectively, for the 80+ year age group. Life expectancy (LE) and LED for 65-year-old individuals are predicted to be 16.1 and 2.2 years in 2030, respectively, with increases of 11.8% and 57.1%, respectively.

CONCLUSIONS

LED in the elderly is predicted to increase more rapidly than LE from 2010 to 2030, both stroke and dementia increasing the risk of disability.

Dual-phase 18F-florbetaben PET provides cerebral perfusion proxy along with beta-amyloid burden in Alzheimer's disease

BACKGROUND

This study investigated changes in brain perfusion and Aβ burden according to the progression of Alzheimer's disease (AD) by using a dual-phase ¹⁸F-florbetaben (FBB) PET protocol.

METHODS

Sixty subjects, including 12 with Aβ-negative normal cognition (Aβ^-NC), 32 with Aβ-positive mild cognitive impairment (Aβ⁺MCI), and 16 with Aβ-positive AD (Aβ⁺AD), were enrolled. A dynamic PET scan was obtained in the early phase (0-10 min, eFBB) and delayed phase (90-110 min, dFBB), which were then averaged into a single frame, respectively. In addition to the averaged eFBB, an R1 parametric map was calculated from the eFBB scan based on a simplified reference tissue model (SRTM). Between-group regional and voxel-wise analyses of the images were performed. The associations between cognitive profiles and PET-derived parameters were investigated.

RESULTS

Both the R1 and eFBB perfusion reductions in the cortical regions were not significantly different between the Aβ^-NC and Aβ⁺MCI groups, while they were significantly reduced from the Aβ⁺MCI to Aβ⁺AD groups in regional and voxel-wise analyses. However, cortical Aβ depositions on dFBB were not significantly different between the Aβ⁺MCI and Aβ⁺AD groups. There were strong positive correlations between the R1 and eFBB images in regional and voxel-wise analyses. Both perfusion components showed significant correlations with general and specific cognitive profiles.

CONCLUSION

The results of this study demonstrated the feasibility of dual-phase ¹⁸F-FBB PET to evaluate different trajectories of dual biomarkers for neurodegeneration and Aβ burden over the course of AD. In addition, both eFBB and SRTM-based R1 can provide robust indices of brain perfusion.

Participant education, spousal education and dementia risk in a diverse cohort of members of an integrated health care delivery system in Northern California

OBJECTIVE

The role of spousal education on dementia risk and how it may differ by gender or race/ethnicity is unknown. This study examines the association between one's own education separate from and in conjunction with spousal education and risk of dementia.

DESIGN

Cohort.

SETTING

Kaiser Permanente Northern California (KPNC), an integrated health care delivery system.

PARTICIPANTS

8835 members of KPNC who were aged 40-55, married and reported own and spousal education in 1964-1973.

PRIMARY OUTCOME MEASURE

Dementia cases were identified through medical records from 1 January 1996 to 30 September 2017.

METHODS

Own and spousal education was self-reported in 1964-1973 and each was classified as four indicator variables (≤high school, trade school/some college, college degree and postgraduate) and as ≥college degree versus <college degree. Age as timescale weighted Cox proportional hazard models adjusted for demographics and health indicators evaluated associations between participant education, spousal education and dementia risk overall and by gender and race/ethnicity.

RESULTS

The cohort was 37% non-white, 46% men and 30% were diagnosed with dementia during follow-up from 1996 to 2017 (mean follow-up=12.7 years). Greater participant education was associated with lower dementia risk independent of spousal education, demographics and health indicators. Greater spousal education was associated with lower dementia adjusting for demographics but became non-significant after further adjustment for participant education. The same pattern was seen for spousal education ≥college degree (not adjusting for participant education HR_{spousal education≥college degree}=0.83 (95% CI: 0.76 to 0.90); adjusting for participant education HR_{spousal education≥college degree}=0.92 (95% CI: 0.83 to 1.01)). These associations did not vary by gender or race/ethnicity.

CONCLUSION

In a large diverse cohort, we found that higher levels of participant's own education were associated with lower dementia risk regardless of spousal education. An inverse association between spousal education and dementia risk was also present, however, the effects became non-significant after adjusting for participant education.

Contribution of IQ in young adulthood to the associations of education and occupation with cognitive ability in older age

Background

Studies suggest that a higher education and occupation are each associated with a higher late-life cognitive ability, but their inter-relationships in their association with cognitive ability and the contribution of peak IQ in young adulthood (‘pre-morbid IQ’) often remain unclear.

Methods

Cross-sectional analysis of 623 participants aged ≥65 years of the BioCog study. Education was coded according to the International Standard Classification of Education (ISCED; range 1 to 6). Occupation was coded as ‘semi/unskilled’, ‘skilled manual’, ‘skilled non-manual’, ‘managerial’, ‘professional’. A summary score of global ability (‘g’) was constructed from six cognitive tests. Pre-morbid IQ was estimated from vocabulary. The Geriatric Depression Scale assessed symptoms of depression. Age- and sex-adjusted analyses of covariance were performed.

Results

Education (partial eta² 0.076; p < 0.001) and occupation (partial eta² = 0.037; p < 0.001) were each significantly associated with g. For education, the association was attenuated but remained statistically significant when pre-morbid IQ was controlled for (partial eta² 0.036; p < 0.001) and was unchanged with additional adjustment for depression (partial eta² 0.037; p < 0.001). For occupation, the association with g was no longer significant when pre-morbid IQ (partial eta² = 0.015; p = 0.06) and depression (partial eta² = 0.011; p = 0.18) were entered as covariates in separate steps. When education and occupation were entered concurrently into the fully adjusted model, only education was independently associated with g (partial eta² 0.030; p < 0.001; occupation, p = 0.93).

Conclusion

While a higher education and a higher occupation were each associated with a higher late-life cognitive ability, only for education some unique contribution to cognitive ability remained over and above its relationship with pre-morbid IQ, depression, and occupation. Further research is needed to address whether a longer time spent in education may promote late-life cognitive ability.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02290-y.

Impact of cardiovascular risk factors and genetics on 10-year absolute risk of dementia: risk charts for targeted prevention

Aims

Dementia is a major global challenge for health and social care in aging populations. A third of all dementia may be preventable due to cardiovascular risk factors. Intensive multi-domain intervention trials targeting primarily cardiovascular risk factors show improved cognitive function in people at risk. Such interventions will, however, be expensive to implement in all individuals at risk and will represent unrealistic economic tasks for most societies. Therefore, a risk score identifying high-risk individuals is warranted.

Methods and results

In 61 664 individuals from two prospective cohorts of the Danish general population, we generated 10-year absolute risk scores for all-cause dementia from cardiovascular risk factors and genetics. In both sexes, 10-year absolute risk of all-cause dementia increased with increasing age, number of apolipoprotein E (APOE) ɛ4 alleles, number of genome-wide association studies (GWAS) risk alleles, and cardiovascular risk factors. The highest 10-year absolute risks of all-cause dementia seen in smoking women with diabetes, low education, APOE ɛ44 genotype, and 22–31 GWAS risk alleles were 6%, 23%, 48%, and 66% in those aged 50–59, 60–69, 70–79, and 80–100, respectively. Corresponding values for men were 5%, 19%, 42%, and 60%, respectively.

Conclusion

Ten-year absolute risk of all-cause dementia increased with age, APOE ɛ4 alleles, GWAS risk alleles, diabetes, low education, and smoking in both women and men. Ten-year absolute risk charts for dementia will facilitate identification of high-risk individuals, those who likely will benefit the most from an early intervention against cardiovascular risk factors.

Late-life sleep duration associated with amnestic mild cognitive impairment

OBJECTIVE

To examine the association between sleep duration in different stages of life and amnestic mild cognitive impairment (aMCI).

DESIGN, SETTING, AND PARTICIPANTS

A total of 2472 healthy elderly and 505 patients with aMCI in China were included in this study. The study analyzed the association between aMCI and sleep duration in different stages of life.

MEASUREMENTS

We compared sleep duration in different stages of life and analyzed the association between Montreal Cognitive Assessment scores and sleep duration by curve estimation. Logistic regression was used to evaluate the association between aMCI and sleep duration.

RESULTS

In the analysis, there were no results proving that sleep duration in youth (P = 0.719, sleep duration < 10 hours; P = 0.999, sleep duration ≥ 10 hours) or midlife (P = 0.898, sleep duration < 9 hours; P = 0.504, sleep duration ≥ 9 hours) had a significant association with aMCI. In the group sleeping less than 7 hours in late life, each hour more of sleep duration was associated with approximately 0.80 of the original risk of aMCI (P = 0.011, odds ratio = 0.80, 95% confidence interval = 0.68-0.95).

CONCLUSIONS

Among the elderly sleeping less than 7 hours, there is a decreased risk of aMCI for every additional hour of sleep.

Does Prolonged Education Causally Affect Dementia Risk When Adult Socioeconomic Status Is Not Altered? A Swedish Natural Experiment in 1.3 Million Individuals

Intervening on modifiable risk factors to prevent dementia is of key importance, since progress-modifying treatments are not currently available. Education is inversely associated with dementia risk, but causality and mechanistic pathways remain unclear. We aimed to examine the causality of this relationship in Sweden using, as a natural experiment, data on a compulsory schooling reform that extended primary education by 1 year for 70% of the population between 1936 and 1949. The reform introduced substantial exogenous variation in education that was unrelated to pupils' characteristics. We followed 18 birth cohorts (n = 1,341,842) from 1985 to 2016 (up to ages 79-96 years) for a dementia diagnosis in the National Inpatient and Cause of Death registers and fitted Cox survival models with stratified baseline hazards at the school-district level, chronological age as the time scale, and cohort indicators. Analyses indicated very small or negligible causal effects of education on dementia risk (main hazard ratio = 1.01, 95% confidence interval: 0.98, 1.04). Multiple sensitivity checks considering only compliers, the pre-/post- design, differences in health-care-seeking behavior, and the impact of exposure misclassification left the results essentially unaltered. The reform had limited effects on further adult socioeconomic outcomes, such as income. Our findings suggest that without mediation through adult socioeconomic position, education cannot be uncritically considered a modifiable risk factor for dementia.

Educational Benefits and Cognitive Health Life Expectancies: Racial/Ethnic, Nativity, and Gender Disparities

BACKGROUND AND OBJECTIVES

To examine racial/ethnic, nativity, and gender differences in the benefits of educational attainment on cognitive health life expectancies among older adults in the United States.

RESEARCH DESIGN AND METHODS

We used data from the Health and Retirement Study (1998-2014) to estimate Sullivan-based life tables of cognitively healthy, cognitively impaired/no dementia, and dementia life expectancies by gender for older White, Black, U.S.-born Hispanic, and foreign-born Hispanic adults with less than high school, high school, and some college or more.

RESULTS

White respondents lived a greater percentage of their remaining lives cognitively healthy than their minority Black or Hispanic counterparts, regardless of level of education. Among respondents with some college or more, versus less than high school, Black and U.S.-born Hispanic women exhibited the greatest increase (both 37 percentage points higher) in the proportion of total life expectancy spent cognitively healthy; whereas White women had the smallest increase (17 percentage points higher). For men, the difference between respondents with some college or more, versus less than high school, was greatest for Black men (35 percentage points higher) and was lowest for U.S.-born Hispanic men (21 percentage points higher).

DISCUSSION AND IMPLICATIONS

Our results provide evidence that the benefits of education on cognitive health life expectancies are largest for Black men and women and U.S.-born Hispanic women. The combination of extended longevity and rising prevalence of Alzheimer's disease points to the need for understanding why certain individuals spend an extended period of their lives with poor cognitive health.