Relationship between education and dementia: an updated systematic review

Social functioning in individuals with Alzheimer's disease and the situation of caregivers

BackgroundChanges in social functioning may be a significant parameter for the early detection of Alzheimer's disease (AD). Currently, research on social functioning in AD across the entire spectrum of the disease is lacking.ObjectiveThe aim of this study was to describe the social functioning of persons with AD at each stage of the disease and to investigate how impaired social functioning affects caregiver burden.MethodsCross-sectional data was derived from memory clinics across Germany as part of the pilot study "Social functioning in individuals with AD and the situation of caregivers". A total of N = 87 relatives providing care for individuals with mild (n = 20), moderate (n = 40), and severe (n = 23) AD were included. Social functioning of individuals with AD was measured via the caregiver-rated German version of the Social Functioning in Dementia Scale (SF-DEM); caregiver burden was assessed using the Zarit Caregiver Burden Interview (ZBI-12). Differences between mild, moderate, and severe AD in terms of sociodemographic characteristics and the level of social functioning were examined. A robust linear regression analysis was conducted to examine the association between social functioning and caregiver burden.ResultsSocial functioning was lower in moderate and severe AD than in mild AD. Higher levels of social functioning were associated with less caregiver burden.ConclusionsThis study highlights the importance of integrating social functioning assessments into clinical practice for improving the early detection, diagnosis and interventions for AD. Early interventions to enhance social functioning may diminish caregiver burden.

A systematic review and meta-analysis on the characteristics of transcranial magnetic stimulation treatment protocols for patients with Alzheimer's disease

BackgroundAlzheimer's disease (AD) is the most common neurodegenerative condition causing dementia. Currently, there has been no established non-pharmacological treatment for cognitive decline in patients with AD. Recent evidence suggests that repetitive transcranial magnetic stimulation (rTMS) may be effective as a non-invasive treatment for improving cognitive function in AD.ObjectiveThis study aimed to examine the characteristics of rTMS treatment protocols for patients with ADMethodsWe conducted a systematic literature search on clinical trials on rTMS for improving cognitive decline in patients with AD, using the PubMed, PsycINFO, and Scopus databases and performed a meta-analysis according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. To clarify which cognitive domains in AD are improved by rTMS, meta-analyses were conducted on both global cognitive function and on each cognitive domain including verbal memory, processing speed, and executive function. In addition, sub-analyses of the treatment details of rTMS parameters including stimulation sites, stimulation frequency, stimulation intensity, and with/without the neuro-navigation technique and meta-regression analyses adjusting for gender, education, and the number of rTMS pulses were performed.ResultsThe results showed significant improvements in global cognitive function, while no significant findings in verbal memory, processing speed and executive function. No significant results were found in subgroup analysis or meta-regression.ConclusionsTo enrich the evidence for cognitive enhancement in AD with rTMS, the randomized controlled trials using a unified rTMS protocol with a larger sample size are warranted.

Cognitive function and associations with demographic, socioeconomic, health and behavioural factors among older adult men and women in rural Bangladesh: a population-based cross-sectional study

Background

Cognitive impairment has a major impact on health, quality of life and survival and its increasing burden presents a critical global health challenge. Empirical population-based studies of cognitive function and its association with demographic, socioeconomic, health and behavioural factors among older adults in low-resource setting are rare. This study describes the burden of cognitive impairment and associations with demographic, health and behavioural factors among older adults in rural Bangladesh.

Methods

We conducted a population-based cross-sectional study of a random sample of men and women aged 60 years and above in 96 rural villages in Bangladesh. Cognitive function was measured using the Bangla Adaptation of the Mini-mental State Examination (BAMSE), where higher score indicates higher function. Blood pressure, height and weight were measured using standard protocols and fasting glucose and 2-h oral glucose test were used to identify diabetes risk. Interviewer administered survey questionnaires assessed depressive symptoms, anxiety and self-reported health behaviours. Analyses were carried out separately for men and women and examined associations between sociodemographic, health and behaviour factors with BAMSE scores using robust Poisson regression.

Findings

Data were gathered from 403 (216 female, 187 male) eligible participants. More than 50% of the population had at least mild cognitive impairment and women had lower cognitive scores than men. Younger age, higher education, wealth, and literacy were significantly associated with higher BAMSE scores among women and men. Associations with marital status varied between men and women, with being married having a positive association with BAMSE among women, i.e. higher cognitive function (relative score ratio (95% CI) 1.08 (1.02, 1.15), p = 0.013), but no association among men (0.94 (0.87, 1.02), p = 0.13). No clear associations were observed with diabetes or hypertension, but overweight and obesity were associated with an increased BAMSE score among women (1.10 (1.02, 1.19), p = 0.011) but not men (1.01 (0.94, 1.10), p = 0.70). Moderate and severe depressive symptoms were associated with lower BAMSE scores among men (0.90 (0.82, 0.99), p = 0.037), but not women (0.94 (0.83, 1.06), p = 0.31). Physical activity was associated with a relative increase in BAMSE score (1.08 (1.01, 1.16), p = 0.020) among women, though no association was seen in men (1.01 (0.95, 1.07), p = 0.76). The consumption of betel was associated with lower BAMSE among women (0.94 (0.89, 1.00), p = 0.056), but there was no evidence of association among men (1.01 (0.96, 1.07), p = 0.61).

Interpretation

A large proportion of older adults in rural Bangladesh have impaired cognitive function and there are important gender differences in the distribution of cognitive scores and their association with demographic, socioeconomic, health and behavioural factors in this population. Improvement in health and social care systems, taking into account the specific social, economic and gender dimensions of the context, are needed to prevent and manage the burden of cognitive decline in rural Bangladesh.

Funding

This survey and analysis were part of the Bangladesh Diabetes Community-Led Awareness, Response and Evaluation (DClare) study funded by UKRI/MRC (MR/T023562/1) under the Global Alliance for Chronic Diseases Scale-Up Programme.

Disparities in Clinical Trial Participation for Hearing Loss Treatment and Cognitive Outcomes in the United States: A Scoping Review

OBJECTIVES

Emerging evidence suggests hearing loss treatment may have a varying impact on modifying the risk of cognitive decline or dementia across different populations. However, it remains unclear whether prior studies have adequately included a diverse range of patient characteristics and dementia risk factors. This study examines participant characteristics in U.S.-based clinical trials investigating associations between hearing aids (HA)/cochlear implants (CI) and cognitive decline.

DATA SOURCES

PubMed, Embase, and Cochrane (inception-December 2024).

REVIEW METHODS

Scoping review following PRISMA-ScR guidelines. Included U.S. trials in peer-reviewed journals on HA/CI and cognitive decline. Participant characteristics were summarized using descriptive statistics and compared to U.S. Census data.

RESULTS

Twenty-two studies (RCTs, non-RCTs, single arm and prospective trials) were included (n = 6-977; mean age: 72.0 years; 66.9% male). Twelve studies utilized HA, and 10 utilized CI. Participants were predominantly White (92.1% ± 9.2), with lower representation among Black (5.4% ± 9.5), Asian (0.1% ± 1.4), and Hispanic/Latino (0.05%; SD not calculatable) populations, reflecting the overrepresentation of White participants (Census 75.3%) and the underrepresentation of others (Census: Black 13.7%, Asian 6.4%, Hispanic/Latino 19.5%). Average education (11.3 ± 2.9 years) was comparable to U.S. averages, and hypertension and diabetes rates (67.2% and 20.1%, respectively) were lower than U.S. age-adjusted rates (74.5% hypertension, 33% diabetes).

CONCLUSIONS

This review of participants characteristics in studies on hearing loss treatment and cognitive decline revealed disparities, particularly in race/ethnicity. Systemic efforts are needed to recruit underrepresented groups to better understand the impact of hearing loss treatment across diverse populations. Bridging these gaps is essential to improving the representativeness of U.S. populations in clinical trials.

Handgrip strength and gait speed relationships with cognitive impairment in Iranian older adults: Birjand longitudinal aging study

BACKGROUND

Cognitive impairment prevalence is rising with population aging. This study examined the relationship between handgrip strength and gait speed with cognitive impairment and performance in older adults.

METHODS

This cross-sectional study used baseline data from Birjand Longitudinal Aging Study (BLAS), including 1347 older adults. Cognitive function was evaluated using the six-item Cognitive Impairment Test (6-CIT). Gait speed was measured over six meters, and grip strength was assessed with hand dynamometers.

RESULTS

After adjusting for potential confounders, the association between low handgrip strength and cognitive impairment lost its significance (relative risk ratio (RRR) = 1.07, 95% CI: 0.70, 1.63). However, low gait speed remained significantly associated with dementia (RRR = 1.92, 95% CI: 1.23, 3.01) after adjusting for age, sex, education, body mass index (BMI), hypertension, and depressive symptoms.

CONCLUSION

Low gait speed is significantly associated with dementia, highlighting the importance of incorporating physical function measures into dementia risk assessments.

Walking reduces the risk of dementia in patients with Parkinson's disease: a longitudinal follow-up study

Background

Physical activity, particularly regular aerobic exercise, is effective in preventing dementia. However, such activities are less feasible for patients with Parkinson's disease (PD) or other motor dysfunctions.

Objectives

In this study, we investigated whether the minimal amount of exercise (MAE) through walking, which is practical for individuals with motor dysfunction, can reduce the risk of dementia in patients with PD.

Design

For this retrospective longitudinal study, we enrolled 470 patients with PD without dementia from 3 centers in Taiwan.

Methods

In total, 187 (39.8%) subsequently developed dementia, whereas 283 (60.2%) did not; the mean follow-up periods for these cohorts were 3.1 (range 0.3-6.1) and 2.4 (range 0.3-6.0) years, respectively. MAE was defined as walking approximately 1500-3000 steps or for 15-30 min. The patients were further stratified by the weekly frequency of MAE into MAE-no (frequency: 0), MAE-weekly (frequency: 1 or 2), and MAE-daily (frequency: ⩾3) groups, respectively. The incidence rates of dementia were compared among the three groups. Cox proportional-hazards analyses were performed to measure the effect of MAE on the incidence of dementia. The statistical model was adjusted for age, sex, education level, cognition level, activities of daily living, neuropsychiatric symptoms, vascular risk factors, and relevant medications.

Results

The MAE-weekly and MAE-daily groups were 0.69 (95% confidence interval (CI): 0.41-1.17) and 0.59 (95% CI: 0.41-0.84) times, respectively, less likely to develop dementia than the MAE-no group. When the MAE-weekly and MAE-daily groups were combined, the hazard ratio for dementia was 0.62 (95% CI: 0.45-0.85). Cox regression revealed that older age, female sex, atrial fibrillation, antidiabetic drug use, and poor daily function were associated with an increased incidence of dementia.

Conclusion

MAE may help prevent dementia in patients with PD. This finding highlights the benefits of walking for patients with PD and, potentially, older adults with motor dysfunction due to various disorders.

Comparisons of four cognitive-frailty measures in predicting dementia and disability

BACKGROUND

Several cognitive-frailty (CF) measurements, such as traditional CF, the CF phenotype, physio-cognitive decline syndrome (PCDS), and motoric cognitive risk syndrome (MCRS) have been developed but their predictive abilities for incident dementia and incident disability are seldom compared. We conducted a 2-year prospective study to compare the associations of traditional CF, the CF phenotype, PCDS, and MCRS with incident dementia and incident disability.

METHODS

In total, 755 individuals aged 65 years or older, without preexisting dementia or disability, participated in the baseline assessment and were subsequently monitored over a 2-year period. Data on cognitive and frailty components of traditional CF, the CF phenotype, PCDS, and MCRS, were collected. The logistic regression model was used to investigate independent associations of each CF measure with incident dementia and incident disability.

RESULTS

In total, 505 participants completed the two annual follow-ups. After adjusting for other CF measures, age, and sex, incident dementia was significantly associated with PCDS (odds ratio [OR] = 2.54; 95% confidence interval [CI], 1.25 ~ 5.19) but was not significantly associated with traditional CF, the CF phenotype, or MCRS, and incident disability was significantly associated with the CF phenotype (OR = 2.90; 95% CI, 1.59 ~ 5.30) but was not significantly associated with traditional CF, PCDS, or MCRS. After adjusting for other CF measures, age, sex, educational level, and other variables, incident dementia was not independently associated with any CF measure, while the association of incident disability with the CF phenotype remained significant (OR = 2.72; 95% CI, 1.45 ~ 5.11).

CONCLUSIONS

The CF phenotype, MCRS, and PCDS can possibly identify a higher number of CF cases than can the traditional CF measure. While the CF phenotype was a significant predictor of incident disability, all four CF measures lacked an independent association with incident dementia over a 2-year period. Future studies with a longer study period are needed to validate our results.

Mediators of educational differences in dementia risk later in life: evidence from the HUNT study

Despite a well-known inverse association between education and dementia risk, the mediating mechanisms are not well understood. We explored how lifestyle and health risk factors across the life-course mediate the relationship between education and dementia among adults aged 70 + years. We included 7,655 participants with dementia diagnoses and education information, using a historical cohort design linking prospective exposure data across the life course from the HUNT4 70 + Study with registry data from Statistics Norway and earlier HUNT surveys. We conducted causal mediation analysis to assess the mediating roles of occupational characteristics, lifestyle factors (smoking, physical inactivity), and health risk factors (obesity, hypertension, diabetes, hearing impairment, cardiovascular diseases, LDL cholesterol, depression, anxiety) assessed during early, middle, and late adulthood in the relationship between education and dementia in later life. Participants with lower education were more likely to have dementia with odds ratios of 1.99, 1.88, 1.83 for the model's accounting exposure to mediators during early, middle, and late adulthood, respectively. These associations were partially mediated by the joint effect of health and lifestyle risk factors from early through late adulthood (mediated 11.55-19.50%). Health risk factors from early to late adulthood jointly mediated 6.85-13.06% of the effect of low education on dementia risk later in life. Additionally, lifestyle factors during middle and late adulthood jointly mediated 4.11-4.96% of the total effect of low education on dementia risk later in life. Educational differences in dementia risk can partly mediated by lifestyle and health factors across the life course. These findings suggest potential targets to address varying dementia risks linked to education levels.

Factors associated with age at tau pathology onset and time from tau onset to dementia

INTRODUCTION

Elevated tau is temporally proximal to dementia onset but less is known about factors influencing T+ onset age and time to dementia following T+ in Alzheimer's disease. We used sampled iterative localized approximation (SILA) estimated T+ onset age (ETOA) to investigate factors associated with T+ age and time from T+ to dementia onset in ADNI.

METHODS

Using SILA-estimated A+ and T+ onset ages derived from 18F-Flortaucipir, 18F-Florbetapir, and 18F-Florbetaben PET and Cox proportional hazards and accelerated failure time models, we analyzed APOE, sex, amyloid burden, age, educational attainment, and literacy associations with ETOA and time from T+ to dementia.

RESULTS

Higher amyloid, APOE-ε4, lower education, and lower literacy associated with younger ETOA. Older ETOA and higher amyloid associated with shorter time from T+ to dementia.

DISCUSSION

This work highlights the prognostic value of ETOA and the need to better characterize factors contributing to ETOA and dementia onset in AD.

Intraindividual variability differentiated older adults with physical frailty and the role of education in the maintenance of cognitive intraindividual variability

OBJECTIVES

Physical frailty is associated with increased risk of cognitive impairment. However, its impact on sustained cognitive processing as evaluated by intraindividual variability (IIV), and factors beneficial to IIV in physically frail older adults remain unexplored. This study aimed to quantify differences in IIV between older adults with and without physical frailty, and examine whether education facilitated maintenance of IIV.

METHODS

This cross-sectional study included 121 community-dwelling older adults 65-90 years with/without physical frailty (PF and non-PF; n = 41 and n = 80 respectively). Physical frailty was determined via Short Physical Performance Battery. Dispersion across the seven components of the Montreal Cognitive Assessment (MoCA) was computed to ascertain IIV. Multivariate analysis of covariance was used to determine group differences in total score and IIV. Four moderation models were constructed to test the effects of education on age-total score and age-IIV relationships in PF and non-PF.

RESULTS

Compared with non-PF, PF showed greater IIV (p = .022; partial η² =  0.044). Among PF, education moderated age-total score (R-sq =  0.084, F =  5.840, p <  0.021) and age-IIV (R-sq =  0.101, F =  7.454, p =  0.010) relationships. IIV increased with age for those with five years (β =  0.313, p =  0.006) or no formal education (β =  0.610, p =  0.001). Greater than seven years of education (β =  0.217, p =  0.050) may be required to maintain IIV at older age.

CONCLUSION

IIV may be a sensitive method to differentiate physically frail older adults. Additionally, perceived cognitive benefits of education may be dependent on physical functioning.

Social determinants of health and risk of dementia among older men and women: A 12-year cohort study in Australia

INTRODUCTION

Social determinants of health (SDH) are recognized as contributing factors to cognitive disorders, but their collective influence on dementia risk remains unclear.

METHODS

A gender-disaggregated analysis was conducted on 12,896 community-dwelling older Australians (mean ± SD age: 75.2 ± 4.3 years; 54% women) without major cognitive impairment upon enrollment. Latent class analysis identified clusters from 72 SDH (70 individual-level and 2 neighborhood-level), while Cox proportional hazards regression estimated dementia risk over 12 years (median: 8.4) follow-up.

RESULTS

Four clusters were identified: least disadvantaged (Class 1: 31.5% men; 30.6% women), most disadvantaged (Class 2: 20.2% men; 19.4% women), high social support with Class 1 features (Class 3: 22.2% men; 24.1% women), and high social support with Class 2 features (Class 4: 26.1% men; 25.7% women). Compared to Class 1, men (HR: 1.49, 95% CI: 1.12-1.98) and women (HR: 1.56, 95% CI: 1.17-2.07) in Class 2, and women in Class 4 (HR: 1.66, 95% CI: 1.28-2.16) had a higher dementia risk.

DISCUSSION

Socioeconomic disadvantage was associated with incident dementia. Despite stronger social support, women's cognitive capacity appeared to be disproportionately impacted by adverse SDH.

HIGHLIGHTS

Four distinct multidimensional clusters were identified from a wide range of 72 social determinants of health. These clusters were associated with dementia risk differently in men and women. In both men and women, the most socioeconomically disadvantaged group had a higher risk of dementia. Despite stronger interpersonal social support, women had a greater risk of dementia. The addition of known dementia risk factors in cluster analysis did not change the findings, suggesting that social determinants of health independently predict dementia risk.

Race and Incident Dementia Among Older Black and Older White Men

The objective of this study was to determine if racial differences exist between older Non-Hispanic Black (NHB) and White (NHW) men in incident dementia over 11 years (2011-2022) in the National Health and Aging Trends Study (NHATS). The analytic sample included 2395 community-dwelling NHB and NHW men free of dementia at baseline who self-identified as Non-Hispanic Black (NHB) and White (NHW). Dementia was assessed at each visit using a validated algorithm developed by NHATS. After adjusting for demographics, place, and health-related characteristics in the Cox proportional hazard models, older NHB men had an increased risk of dementia (hazard ratio: 1.63, 95% confidence interval: [1.22-2.17]) compared to older NHW men. There may be unique factors such as stressors, patterns of genes, or perhaps nutrition that older NHB men possess and experience throughout their lives that contribute to the increased incident dementia.

Modifiable risk factors for early- and late-onset dementia using the Korean national health insurance service database

BACKGROUND

Early-onset dementia (EOD) and late-onset dementia (LOD) may have distinct modifiable risk-factor profiles.

OBJECTIVE

To identify and compare factors associated with EOD and LOD using a nationwide cohort database.

DESIGN

Nationwide two nested case-control studies.

SETTING

We used the National Health Insurance Service-National Sample Cohort database (2004-2019).

PARTICIPANTS

The initial sample size was 514,866; 5157 EOD and 39,326 LOD cases were matched 1:1 with controls based on age, sex, and the Charlson Comorbidity Index.

MEASUREMENTS

Socioeconomic status, residential area, body mass index, alcohol consumption, smoking status, physical activity, blood pressure, and laboratory findings were analyzed. Multivariable logistic regression models were used to identify the risk factors.

RESULTS

Higher socioeconomic status and increased frequency of physical activity were associated with a lower risk of both EOD and LOD. Rural residence, heavy alcohol consumption, and higher fasting blood sugar levels were associated with an increased risk of LOD, although there was no significant association with EOD. Overall, these factors impacted LOD more strongly than EOD. Demographic and lifestyle factors had a greater effect on LOD than blood pressure and relevant laboratory findings.

CONCLUSION

Modifiable risk factors were associated with LOD and EOD. The influence of some modifiable risk factors was more pronounced in the LOD group than in the EOD group. Identifying modifiable risk factors associated with dementia can aid in the development of preventive strategies, underscoring the clinical importance of our findings.

Survival disparities among Alzheimer's disease patients in Hawaii

BackgroundSurvival after an Alzheimer's disease (AD) diagnosis is vital for patients, their families, caregivers, and healthcare providers. Hawaii, known for its diverse ethnic population, exhibits significant racial health disparities.ObjectiveThis study examined racial/ethnic and socioeconomic disparities in AD survival in Hawaii and developed machine learning models to predict overall survival using Hawaii Medicare data.MethodsNine years of Hawaii Medicare data were utilized to gather information on AD development after age 65, following patients to capture all-cause survival or until censoring. The study examined the effects of race/ethnicity and socioeconomic status (SES) on mortality risk. Cox regression analysis was conducted on overall survival, accounting for covariates. A Survival Random Forest was employed to model survival, incorporating K years of longitudinal health profiles.ResultsThe study included 9393 AD subjects. Analysis revealed that Asian Americans (AA) had a later age at AD diagnosis (p < 0.001), with an average age of 85.9, compared to 82.7 and 83.3 years for whites and Native Hawaiians and Pacific Islanders (NHPI), respectively. Low SES showed a marginal increase in hazard (Hazard Ratio [HR] = 1.36, p < 0.001). After covariate adjustment, compared to AAs with better SES, increased hazards were found for their white counterpart (HR = 1.18, p < 0.001) and groups with low SES: AA (HR = 1.28, p < 0.001), white (HR = 1.51, p < 0.001), and NHPI (HR = 1.39, p < 0.001). The predictive model had a Concordance-Index of 0.82, showing reasonable predictability.ConclusionsRacial/ethnic and SES disparities significantly influence AD onset and survival. Combined with longitudinal health status data, machine learning demonstrates reasonable predictability of survival.

Mediation of the association between education and dementia by occupational complexity, income, health behaviours and health outcomes

BACKGROUND

Many studies observe a negative association between education and all-cause dementia, however, little is known about how the association develops. Current evidence regarding mediatory factors is limited, conflicted and suggests a complex relationship. In this study we used UK Biobank data to determine to what extent multiple factors mediate the association.

METHODS

Data was sourced from UK Biobank and multiple imputation used to replace missing values. Education was measured at baseline assessment and dementia diagnosis determined from self-report or linked healthcare records. Five potential mediators were considered: Social isolation, income and occupational complexity were measured at baseline and health behaviour and health outcome scores derived. Logistic regression was used to examine the association between education and dementia with adjustment for potential mediators. Causal mediation analysis was then performed to determine the proportion of the dementia education association occurring via each mediatory pathway.

RESULTS

In a sample of 384,284 participants, higher level of education was associated with reduced odds of dementia. When considered as a confounder, occupational complexity almost fully attenuated the association (OR: 0.94, CI: 0.89-0.99) and was found to mediate 73% of the association. Average income, health outcomes and health behaviours also acted as mediators, explaining 10%, 27% and 35% of the relationship respectively.

CONCLUSIONS

Occupational complexity mediates a large proportion of the association between education and dementia. Intervention to improve access to cognitively stimulating work and leisure activities, particularly to those who are less educated, may reduce the number of people in the UK living with dementia.

Relationship between Sarcopenia and minimal hepatic encephalopathy in patients with cirrhosis: a prospective observational study

BACKGROUND

Sarcopenia, characterized by loss of muscle mass and function, has gained importance in the evaluation of cirrhotic patients. Evidence suggests its role in adverse clinical outcomes, including minimal hepatic encephalopathy (MHE). This study aimed to investigate the association between sarcopenia and MHE in patients with cirrhosis.

METHODS

We prospectively enrolled outpatients with cirrhosis to assess sarcopenia using the 2019 criteria from the Asian Working Group for Sarcopenia. MHE was diagnosed through the Psychometric Hepatic Encephalopathy Score.

RESULTS

Of the 210 cirrhotic patients (57.1% male, mean age 62.7 ± 9.6 years), 54 (25.7%) had sarcopenia, with 26 (12.3%) classified as severe. Thirty-seven patients (17.6%) were diagnosed with MHE. Sarcopenia prevalence was significantly higher in patients with MHE compared to those without MHE (45.9% vs. 21.4%). MHE was significantly associated with age, education level, Mini-Mental State Examination score, and a history of hepatic decompensation. No significant associations were found regarding gender, body mass index, comorbidities, sleep quality, and the etiology of cirrhosis. Multivariable logistic regression showed that MHE was significantly associated with age (adjusted odds ratio [aOR] 1.08, 95% CI 1.02-1.13), sarcopenia (aOR 3.29, 95% CI 1.44-7.50), history of overt hepatic encephalopathy (aOR 7.40, 95% CI 1.20-45.56), and variceal bleeding (aOR 3.13, 95% CI 1.38-7.10). Severe sarcopenia was also independently associated with MHE (aOR 3.64, 95% CI 1.32-10.05).

CONCLUSIONS

Sarcopenia is prevalent in cirrhotic patients and is associated with an increased risk of MHE. Our findings emphasize the importance of assessing sarcopenia to potentially mitigate MHE risk in managing patients with cirrhosis.

Augmenting Cognitive Function in the Elderly with Mild Cognitive Impairment Using Probiotic Lacticaseibacillus rhamnosus CBT-LR5: A 12-Week Randomized, Double-Blind, Parallel-Group Non-Comparative Study

BACKGROUND

Probiotics have been shown to enhance cognitive function in individuals with mild cognitive impairment (MCI), but their efficacy varies, depending on the strain and dosage.

OBJECTIVES

Clinical investigations are crucial to confirm their safety, efficacy, and mechanism of action. This study was designed to assess the effective dosage, safety, and efficacy of MH-Pro, a test product containing Lacticaseibacillus rhamnosus CBT-LR5 (LR5) and skim milk (non-fat dry milk), in improving cognitive function and related physiological changes in older adults suspected of MCI over 12 weeks.

METHODS

In total, 20 participants (mean age: 68.9 years) were randomly assigned in a 1:1 ratio to either a low-dose group (1 × 1010 CFU LR5 with 1622 mg) or a high-dose group (1 × 1010 CFU LR5 with 4055 mg skim milk) in a double-blind, parallel-group clinical trial.

RESULTS

After 12 weeks, the low-dose group showed significant improvements in the MOCA-K subdomains, specifically in naming (p = 0.01) and delayed recall (p = 0.003). Additionally, levels of amyloid-β1 40/42 in the blood significantly decreased (p = 0.03) following supplementation in the low-dose group. The high-dose group exhibited significant improvement in orientation (p = 0.05). Moreover, overall cognitive enhancement was observed in the low-dose group (p = 0.003), while the high-dose group showed a trend toward improvement (p = 0.06). Fecal analysis revealed significant changes in bacterial composition, with an increase in Lacticaseibacillus after 12 weeks of MH-Pro consumption. Together, these findings provide foundational evidence suggesting that MH-Pro supplementation may serve as a potential intervention for enhancing cognitive function through gut-brain axis pathways in the elderly population. However, given the small sample size and the predominance of female participants, the impact of the outcome may be limited. Further large-scale studies are necessary to validate these preliminary results.

CONCLUSIONS

This study provides foundational evidence to recognize the use of LR5 and skim milk to prepare a probiotic supplement that enhances cognitive function in the aging population.

Reevaluating the Role of Education in Cognitive Decline and Brain Aging: Insights from Large-Scale Longitudinal Cohorts across 33 Countries

Why education is linked to higher cognitive function in aging is fiercely debated. Leading theories propose that education reduces brain decline in aging, enhances tolerance to brain pathology, or that it does not affect cognitive decline but rather reflects higher early-life cognitive function. To test these theories, we analyzed 407.356 episodic memory scores from 170.795 participants > 50 years, alongside 15.157 brain MRIs from 6.472 participants across 33 Western countries. More education was associated with better memory, larger intracranial volume and slightly larger volume of memory-sensitive brain regions. However, education did not protect against age-related decline or weakened effects of brain decline on cognition. The most parsimonious explanation for the results is that the associations reflect factors present early in life, including propensity of individuals with certain traits to pursue more education. While education has numerous benefits, the notion that it provides protection against cognitive or brain decline is not supported.

Prevalence of motoric cognitive risk syndrome among older adults in Brazil and evaluation of effect modification by race

BACKGROUND

Motoric cognitive risk syndrome (MCRS) is a pre-dementia syndrome of growing interest, yet it remains understudied in Latin America with a significant lack of information on the interaction between its risk factors and race.

OBJECTIVE

To estimate the prevalence of MCRS among older adults in Brazil, investigate its association with various clinical and sociodemographic variables, and explore the potential of effect modification by race.

METHODS

This cross-sectional, population-based study was conducted among community-dwelling older adults in Brazil, with data collected between 2015 and 2016. The diagnosis of MCRS was established following the standard recommended by the original study that first described it. We used Poisson regression models to analyze the association between MCRS and a list of 21 variables identified from a systematic review.

RESULTS

A total of 4677 participants aged 60 years and older were included. The prevalence of MCRS in the Brazilian population of older adults was 4.34% (95% CI: 3.20%-5.48%). Higher levels of education and physical activity showed protective associations with MCRS, while depression and stroke demonstrated risk associations. A significant cross-over interaction between race and depression regarding MCRS was observed, such that the association of depression with MCRS was approximately three times higher among White individuals than Black individuals.

CONCLUSIONS

Our results challenge previous estimates that Latin America is the region with the highest prevalence of MCRS among older adults and signal the need for further studies to better investigate the modification of effect of the association between depression and MCRS by race.

Reevaluating the Role of Education in Cognitive Decline and Brain Aging: Insights from Large-Scale Longitudinal Cohorts across 33 Countries

Why education is linked to higher cognitive function in aging is fiercely debated. Leading theories propose that education reduces brain decline in aging, enhances tolerance to brain pathology, or that it does not affect cognitive decline but rather reflects higher early-life cognitive function. To test these theories, we analyzed 407.356 episodic memory scores from 170.795 participants >50 years, alongside 15.157 brain MRIs from 6.472 participants across 33 Western countries. More education was associated with better memory, larger intracranial volume and slightly larger volume of memory-sensitive brain regions. However, education did not protect against age-related decline or weakened effects of brain decline on cognition. The most parsimonious explanation for the results is that the associations reflect factors present early in life, including propensity of individuals with certain traits to pursue more education. While education has numerous benefits, the notion that it provides protection against cognitive or brain decline is not supported.

Impact of Anticholinergic Burden and Clinical-Demographic Characteristics on Incident Dementia in Parkinson Disease

PURPOSE

Anticholinergic medication use measured via the Anticholinergic Cognitive Burden (ACB) scale has been associated with an increased dementia incidence in older adults but has not been explored specifically for Parkinson disease dementia (PDD). We used adjusted Cox models to estimate the risk of incident PDD associated with demographic factors, clinical characteristics, and time-varying total ACB in a longitudinal, deeply-phenotyped prospective PD cohort.

MAJOR FINDINGS

56.5% of study participants were taking ACB-scale drugs at enrollment. Increasing age, motor symptom burden and psychosis were associated with PDD risk. Female sex and educational achievement were protective against PDD. ACB categories were not associated with PDD overall, but depression and impulse control disorder were strongly associated with PDD in a subsample with high baseline ACB.

CONCLUSIONS

Patient and clinical factors modify PDD risk. PD drug safety and drug-disease interaction studies may require considering multiple mechanisms and including dose-based, prospectively acquired medication exposure measures.

Emergency Medical Services Provider-Perceived Alzheimer's Disease and Related Dementias in the Prehospital Setting

Objective

Our goal was to assess emergency medical services (EMS) provider-perceived Alzheimer's disease and related dementias (ADRD) by patient sociodemographic characteristics and ZIP code tabulation areas (ZCTA) in the prehospital setting.

Methods

We conducted a retrospective descriptive analysis of EMS calls with patient contact for adults ≥ 65 years of age who were provided prehospital care between February 1, 2020 and January 31, 2022, using data from the San Francisco Department of Emergency Management and the 2021 American Community Survey. Logistic regression models assessed the associated between EMS provider-perceived ADRD and patient sociodemographic characteristics, including age, race/ethnicity, incident location, and ZCTA-level socioeconomic status.

Results

A total of 55,129 patient encounters were recorded, with EMS provider-perceived ADRD recorded in 4,112 (7.5%). Among cases with EMS provider-perceived ADRD, the most common primary impressions were mental disorders (17.1%), weakness (17.0%), injury (15.7%), and pain (13.1%). Increasing age was associated with higher odds of EMS provider-perceived ADRD among both sexes. Among females, EMS provider-perceived ADRD was higher among Hispanics (odds ratio [OR] 1.30, 95% confidence interval [CI] 1.11-1.52), Blacks (OR 1.20, 95% CI 1.03-1.40), Asians (OR 1.18, 95% CI 1.06-1.31), and Native Hawaiian and Pacific Islanders (OR 1.48, 95% CI 1.05-2.08]), while among males, only Asians (OR 87, 95% CI .76-.99) had lower odds, all compared to Whites. Females in low- and medium-income ZCTAs had lower odds of EMS provider-perceived ADRD relative to high-income ZCTAs, with no significant findings in males.

Conclusion

Our findings suggest a higher prevalence of EMS provider-perceived Alzheimer's disease and related dementias among minoritized and socioeconomically disadvantaged populations, including the oldest adults, and racial and ethnic minority communities. Future research and more precise data collection is needed to ensure equity for older adults who access emergency care in the prehospital setting.

Non-canonical pathways associated to Amyloid beta and tau protein dyshomeostasis in Alzheimer's disease: A narrative review

Alzheimer's Disease (AD) is the most common form of dementia among elderly people. This disease imposes a significant burden on the healthcare system, society, and economy due to the increasing global aging population. Current trials with drugs or bioactive compounds aimed at reducing cerebral Amyloid beta (Aβ) plaques and tau protein neurofibrillary tangles, which are the two main hallmarks of this devastating neurodegenerative disease, have not provided significant results in terms of their neuropathological outcomes nor met the expected clinical end-points. Ageing, genetic and environmental risk factors, along with different clinical symptoms suggest that AD is a complex and heterogeneous disorder with multiple interconnected pathological pathways rather than a single disease entity. In the present review, we highlight and discuss various non-canonical, Aβ-independent mechanisms, like gliosis, unhealthy dietary intake, lipid and sugar signaling, and cerebrovascular damage that contribute to the onset and development of AD. We emphasize that challenging the traditional "amyloid cascade hypothesis" may improve our understanding of this age-related complex syndrome and help fight the progressive cognitive decline in AD.

Differences in dementia prevention knowledge by educational attainment: an analysis of a household survey from Great Britain

Background

Higher levels of education are associated with slower cognitive decline and a lower risk of dementia, with some evidence of a causal relationship. However, the mechanisms explaining these associations are not well established.

Methods

We collected data on dementia knowledge using a cross-sectional household survey representative of the population of Great Britain. Dementia knowledge was assessed using a self-reported measure and a question measuring the knowledge of key risk factors. We examined whether dementia knowledge varied by levels of education (as measured by the level of the highest qualification) by fitting logistic regressions adjusted for confounding factors.

Findings

Out of the 5036 respondents aged 25 or over (46.6% male; average age 63.8), 9.3% reported knowing a great deal about dementia, and 32.2% quite a lot. We found a strong educational gradient in dementia prevention knowledge. For people with a degree qualification compared with people with no formal qualification, the ORs of reporting having quite a lot or a great deal of knowledge about dementia were 2.54 (95% CIs 1.81 to 3.56). The ORs were 3.58 (2.61 to 4.91) for mentioning all risk factors. The difference in awareness by educational level was largest for some risk factors such as lack of physical and mental activity, alcohol consumption and poor mental health.

Interpretation

The protective effect of higher levels of education against the risk of dementia may partly be driven by differences in dementia prevention knowledge. Health education efforts on dementia prevention should target people with lower levels of education to reduce inequalities in dementia prevalence.

Age-related effects on a hierarchical structure of canine cognition

The current study investigates whether there are statistically independent age-related influences on the canine cognitive structure and how individual factors moderate cognitive aging on both cross-sectional and longitudinal samples. A battery of seven tasks was administered to 129 pet dogs, on which exploratory and confirmatory factor analyses were employed to unveil the correlational structure underlying individual differences in cognitive performance. The best-fitting model featured a hierarchical structure with two first-order cognitive domains (individual problem solving, learning) and a second-order common factor. These higher order factors exhibited consistency over a period of at least 2.5 years. External validation linked the common factor positively to discrimination and reversal learning performance, exploration, neophilia, activity/excitability, and training level while negatively to cognitive dysfunction symptoms, suggesting that it is a good candidate for a general cognitive factor (canine g). Structural equation models identified three distinct age-related influences, operating on associative learning, on memory, and on canine g. Health status moderated the negative age-canine g relationship, with a stronger association observed in dogs with poorer health status, and no relationship for dogs in good health. On a longitudinal sample (N = 99), we showed that the direction and magnitude of change in canine g over up to 3 years is affected by various interactions between the dogs' age, communication score, baseline performance, and time elapsed since the baseline measurement. These findings underscore the presence of a general cognitive factor in dogs and reveal intriguing parallels between human and canine aging, affirming the translational value of dogs in cognition and aging research.

A Dual Group-Based 11-Year Trajectory Analysis of Cognitive Impairment and Transport Restriction for Community-Dwelling Older Adults

OBJECTIVES

To examine the trajectories of cognitive impairment and transport restriction over time and the interrelation between these trajectories among older adults.

METHODS

Group-based trajectory modeling was used on the longitudinal National Health and Aging Trends Study (NHATS) over 11 years from 2011 to 2021, among 5753 participants, stratified by age in 2011 to three groups of 65-74 years, 75-84 years, and 85 years and above.

RESULTS

For transport restrictions, these trajectory groups were: (1) a majority with no restrictions, (2) low and increasing or stable, and (3) moderate or high and decreasing. The overall pattern was largely consistent across the three age groups, with the older group showing a higher predicted likelihood of transport restrictions compared to the younger group. For each of the three age groups, there were two cognitive impairment trajectories including (1) low and (2) increasing cognitive impairment. The proportions of increasing cognitive impairment were 12.3% among the 65-74 years old, 27.3% among the 75-84 years old, and 40.4% among the 85 years and above old. Compared with those with no transport restriction, the other two trajectories with either low or moderate transport restrictions were more likely to belong to increasing cognitive impairment. The odds ratio was 3.06 (95% CI 2.0-4.68) for low & increasing transport restrictions versus 1.57 (95% CI 0.96-2.56) for moderate & decreasing transport restrictions among 65-74 years old. The odds ratio was 2.38 (95% CI 1.68-3.38) for low & increasing transport restrictions versus 1.88 (95% CI 1.39-2.55) for moderate & decreasing transport restrictions among 75-84 years old.

CONCLUSIONS

Cognitive impairment was more likely to co-occur with those with low and increasing transport restrictions than with those with moderate and decreasing transport restrictions. Addressing transport restriction among older adults holds the potential to ameliorate cognitive outcomes.

Regular physical activity and high educational attainment positively affect cognitive function among older adults

Although educational attainment and physical activity tend to determine cognitive function among older adults, studies have shown inconsistent results. This study aimed to examine how physical activity and educational attainment relate to the cognitive function of older adults. Educational attainment was determined based on the total number of years of education received from formal educational institutions. All participants were classified as active or sedentary according to the Stanford Brief Activity Survey. Thereon, the participants were divided into four groups based on educational attainment and physical activity levels: the low education-sedentary (LESG; n=29, 74.06±5.39 years), low education-active (LEAG; n=34, 73.97±4.74 years), high education-sedentary (HESG; n=26, 74.34±5.17 years), and high education-active groups (HEAG; n=26, 74.11±4.53 years). Four domains of cognitive function were assessed using the Seoul Neuropsychological Screening Battery: attention, visuospatial function, memory, and frontal/executive function. Linear regression analyses were performed to investigate differences in cognitive function between the four groups, setting the low education-sedentary group as the reference. Among the domain of cognitive function, attention differed significantly in the LESG from that in the HESG and HEAG. Educational attainment and physical activity levels influence cognitive function. A greater number of early-life educational experiences and regular physical activity in old age enhanced the cognitive function of older adults.

Modeling multiple-criterion diagnoses by heterogeneous-instance logistic regression

Mild cognitive impairment (MCI) is a prodromal stage of Alzheimer's disease (AD) that causes a significant burden in caregiving and medical costs. Clinically, the diagnosis of MCI is determined by the impairment statuses of five cognitive domains. If one of these cognitive domains is impaired, the patient is diagnosed with MCI, and if two out of the five domains are impaired, the patient is diagnosed with AD. In medical records, most of the time, the diagnosis of MCI/AD is given, but not the statuses of the five domains. We may treat the domain statuses as missing variables. This diagnostic procedure relates MCI/AD status modeling to multiple-instance learning, where each domain resembles an instance. However, traditional multiple-instance learning assumes common predictors among instances, but in our case, each domain is associated with different predictors. In this article, we generalized the multiple-instance logistic regression to accommodate the heterogeneity in predictors among different instances. The proposed model is dubbed heterogeneous-instance logistic regression and is estimated via the expectation-maximization algorithm because of the presence of the missing variables. We also derived two variants of the proposed model for the MCI and AD diagnoses. The proposed model is validated in terms of its estimation accuracy, latent status prediction, and robustness via extensive simulation studies. Finally, we analyzed the National Alzheimer's Coordinating Center-Uniform Data Set using the proposed model and demonstrated its potential.

Differences in cognitive function at 18 y of age explain the association between low education and early dementia risk

Major initiatives attempt to prevent dementia by targeting modifiable risk factors. Low education is frequently pointed to, due to its relationship with dementia. Impact of education is difficult to assess, however, because of associations with multiple other factors, requiring large population-representative samples to tease the relationships apart. We studied 207,814 Norwegian men born between 1950 and 1959 who underwent compulsory cognitive testing during military conscription as young adults, to systematically test associations of education, cognition, and other important factors. Participants were grouped into five education levels and seven cognitive levels. A total of 1,521 were diagnosed with dementia between ages 60 and 69 y. While having compulsory education only was associated with increased risk (Hazard ratio [HR] = 1.37, CI: 1.17 to 1.60), this association was markedly attenuated when controlling for cognitive test scores (HR = 1.08, CI: 0.91 to 1.28). In contrast, low cognitive score was associated with double risk of later diagnosis, even when controlling for education (HR = 2.00, CI: 1.65 to 2.42). This relationship survived controlling for early-life socioeconomic status and replicated within pairs of brothers. This suggests that genetic and environmental factors shared within families, e.g., common genetics, parental education, socioeconomic status, or other shared experiences, cannot account for the association. Rather, independent, nonfamilial factors are more important. In contrast, within-family factors accounted for the relationship between low education and diagnosis risk. In conclusion, implementing measures to increase cognitive function in childhood and adolescence appears to be a more promising strategy for reducing dementia burden.

The impact of education as a proxy for lifestyle habits on reducing the association with dementia prevalence in the Southern Region of Brazil

Objectives

This study aimed to investigate the prevalence of dementia among older adults from Florianópolis, in the Southern Region of Brazil.

Methods

Data were originally drawn from the Epifloripa Aging Cohort Study, a representative and community-based survey designed to evaluate older people's health. This cross-sectional study was conducted in two phases: the community-screening phase, in which the Mini-Mental State Examination and a multifunctional scale were administered to older subjects and close informants, respectively; and the hospital-diagnosis phase, when the Cambridge Examination and the National Institute on Aging criteria were used. Adjustment for screening accuracy was made in order to estimate dementia prevalence.

Results

Of 1184 subjects evaluated in the community, 243 were screened for the diagnosis phase, in which 47 were identified with dementia, resulting in a crude prevalence of 4.5% (95% CI: 3.241-5.758) and an estimated prevalence of 9.2% (95% CI: 7.446-10.954). Dementia was associated with older ages, lower education levels, and the presence of stroke. Mild alcohol use (in comparison with no alcohol use), community-group practice, internet use and a higher level of physical activity, rather than education, decreased the odds ratio for dementia. Education was directly associated with these lifestyle habits.

Conclusions

Prevalence was lower than that in previous studies in the country, and multivariate analysis reinforced the importance of lifestyle in preventing cognitive disorders in the older population.

Association of aortic valve calcium with dementia and stroke: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND AND AIMS

Calcific aortic valve disease is associated with increased thrombin formation, platelet activation, decreased fibrinolysis, and subclinical brain infarcts. We examined the long-term association of aortic valve calcification (AVC) with newly diagnosed dementia and incident stroke in the Multi-Ethnic Study of Atherosclerosis (MESA).

METHODS

AVC was measured using non-contrast cardiac CT at Visit 1. We examined AVC as a continuous (log-transformed) and categorical variable (0, 1-99, 100-299, ≥300). Newly diagnosed dementia was adjudicated using International Classification of Disease codes. Stroke was adjudicated from medical records. We calculated absolute event rates (per 1000 person-years) and multivariable adjusted Cox proportional hazards ratios (HR).

RESULTS

Overall, 6812 participants had AVC quantified with a mean age of 62.1 years old, 52.9 % were women, and the median 10-year estimated atherosclerotic cardiovascular disease (ASCVD) risk was 13.5 %. Participants with AVC >0 were older and less likely to be women compared to those with AVC=0. Over a median 16-year follow-up, there were 535 cases of dementia and 376 cases of stroke. The absolute risk of newly diagnosed dementia increased in a stepwise pattern with higher AVC scores, and stroke increased in a logarithmic pattern. In multivariable analyses, AVC was significantly associated with newly diagnosed dementia as a log-transformed continuous variable (HR 1.09; 95 % CI 1.04-1.14) and persons with AVC ≥300 had nearly a two-fold higher risk (HR 1.77; 95 % CI 1.14-2.76) compared to those with AVC=0. AVC was associated with an increased risk of stroke after adjustment for age, sex, and race/ethnicity, but not after adjustment for ASCVD risk factors.

CONCLUSIONS

After multivariable adjustment, AVC >0 was significantly associated with an increased risk of newly diagnosed dementia, but not incident stroke. This suggests that AVC may be an important risk factor for the long-term risk of dementia beyond traditional ASCVD risk factors.

Association of Seizure Control With Cognition in People With Normal Cognition and Mild Cognitive Impairment

BACKGROUND AND OBJECTIVES

Seizures are common in dementia and associated with accelerated cognitive decline. However, the impact of active vs remote seizures on cognition remains understudied. This study aimed to investigate the impact of active vs remote seizures on cognition in people with normal cognition and mild cognitive impairment (MCI).

METHODS

This longitudinal, multicenter cohort is based on National Alzheimer's Coordinating Center data of participants recruited from 39 Alzheimer's Disease Centers in the United States from September 2005 to December 2021. All participants with normal cognition and MCI and at least 2 visits were included. Primary outcome, that is, cognitive decline, was determined using Clinical Dementia Rating (CDR) from (1) normal-to-impaired (CDR ≥0.5) and (2) MCI-to-dementia (CDR ≥1) groups. The effect of active seizures (over the preceding 12 months), remote seizures (previous seizures but none over the preceding 12 months), and no seizures (controls) on cognition was assessed. Subgroups of chronic seizures at enrollment and new-onset seizures were further analyzed. Cox regression models assessed the risk of all-cause MCI and/or dementia. All models were adjusted for age, sex, education, race, hypertension, and diabetes.

RESULTS

Of the 13,726 participants with normal cognition at enrollment (9,002 [66%] female; median age 71 years), 118 had active seizures and 226 had remote seizures. Of the 11,372 participants with MCI at enrollment (5,605 [49%] female; median age 73 years), 197 had active seizures and 226 had remote seizures. Active seizures were associated with 2.1 times higher risk of cognitive impairment (adjusted hazard ratio [aHR] 2.13, 95% CI 1.60-2.84, p < 0.001) in cognitively healthy adults (median years to decline: active seizures = ∼1, remote seizures = ∼3, no seizures = ∼3) and 1.6 times higher risk of dementia (aHR 1.58, 95% CI 1.24-2.01, p < 0.001) in those with MCI (median years to decline: active seizures = ∼1, remote seizures = ∼2, controls = ∼2). This risk was not observed with remote seizures.

DISCUSSION

In this study, active seizures but not remote seizures were associated with earlier cognitive decline in both cognitively normal adults and those with MCI, independent of other dementia risk factors. Therefore, early identification and management of seizures may present a path to mitigation of cognitive decline in the aging epileptic population. A limitation is that causality cannot be confirmed in our observational longitudinal study.

Association of education attainment, smoking status, and alcohol use disorder with dementia risk in older adults: a longitudinal observational study

BACKGROUND

Previous research on the risk of dementia associated with education attainment, smoking status, and alcohol use disorder (AUD) has yielded inconsistent results, indicating potential heterogeneous treatment effects (HTEs) of these factors on dementia risk. Thus, this study aimed to identify the important variables that may contribute to HTEs of these factors in older adults.

METHODS

Using 2005-2021 data from the National Alzheimer's Coordinating Center (NACC), we included older adults (≥ 65 years) with normal cognition at the first visit. The exposure of interest included college education or above, current smoking, and AUD and the outcome was all-cause dementia. We applied doubly robust learning to estimate risk differences (RD) and 95% confidence intervals (CI) between exposed and unexposed groups in the overall cohort and subgroups identified through a decision tree model.

RESULTS

Of 10,062 participants included, 929 developed all-cause dementia over a median 4.4-year follow-up. College education or above was associated with a lower risk of all-cause dementia in the overall population (RD, -1.5%; 95%CI, -2.8 to -0.3), especially among the subpopulations without hypertension, regardless of the APOE4 status. Current smoking was not related to increased dementia risk overall (2.8%; -1.5 to 7.2) but was significantly associated with increased dementia risk among men with (21.1%, 3.1 to 39.1) and without (8.4%, 0.9 to 15.8) cerebrovascular disease. AUD was not related to increased dementia risk overall (2.0%; -7.7 to 11.7) but was significantly associated with increased dementia risk among men with neuropsychiatric disorders (31.5%; 7.4 to 55.7).

CONCLUSIONS

Our studies identified important factors contributing to HTEs of education, smoking, and AUD on risk of all-cause dementia, suggesting an individualized approach is needed to address dementia disparities.

A critique and examination of the polysocial risk score approach: predicting cognition in the Health and Retirement Study

Polysocial risk scores were recently proposed as a strategy for improving the clinical relevance of knowledge about social determinants of health. Our objective in this study was to assess whether the polysocial risk score model improves prediction of cognition and all-cause mortality in middle-aged and older adults beyond simpler models including a smaller set of key social determinants of health. We used a sample of 13 773 individuals aged ≥50 years at baseline from the 2006-2018 waves of the Health and Retirement Study, a US population-based longitudinal cohort study. Four linear mixed models were compared: 2 simple models including a priori-selected covariates and 2 polysocial risk score models which used least absolute shrinkage and selection operator (LASSO) regularization to select covariates among 9 or 21 candidate social predictors. All models included age. Predictive accuracy was assessed via R2 and root mean-squared prediction error (RMSPE) using training/test split validation and cross-validation. For predicting cognition, the simple model including age, race, sex, and education had an R2 value of 0.31 and an RMSPE of 0.880. Compared with this, the most complex polysocial risk score selected 12 predictors (R2 = 0.35 and RMSPE = 0.858; 2.2% improvement). For all-cause mortality, the simple model including age, race, sex, and education had an area under the receiver operating characteristic curve (AUROC) of 0.747, while the most complex polysocial risk score did not demonstrate improved performance (AUROC = 0.745). Models built on a smaller set of key social determinants performed comparably to models built on a more complex set of social "risk factors."

School-based racial segregation, social support, and late-life cognitive function in the Study of Healthy Aging in African Americans (STAR)

INTRODUCTION

School-based social support for Black students may mediate or modify the association between school segregation and late-life cognition.

METHODS

Study of Healthy Aging in African Americans participants (n = 574) reported segregated school attendance and school-based social support. Associations of segregated schooling with domain-specific cognitive outcomes and effect modification or mediation by school-based social support were evaluated with linear mixed models.

RESULTS

Segregated school attendance was associated with increased likelihood of school-based social support. Segregated (vs. desegregated in 6th grade) school attendance was associated with lower executive function (β = -0.18 [-0.34, -0.02]) and semantic memory z-scores (β = -0.31 [-0.48, -0.13]). Social support did not mediate these associations. Estimates for segregated school attendance were attenuated among those who felt supported, although there was limited evidence of statistically significant effect modification.

DISCUSSION

Early-childhood school segregation was associated with poorer cognitive function. Sources of resilience within racialized educational experiences should be further evaluated to bridge inequities.

HIGHLIGHTS

School segregation is a form of structural racism that affected the educational experiences of Black youth with potentially lasting consequences for healthy brain aging. Black students who attended a segregated school experienced greater school-based social support, which may highlight a potential source of resilience and resistance against the effects of racism-related stressors on cognitive function. The estimated adverse association between attending a segregated school on cognition was larger for students without an adult at school who cared about them versus those with an adult at school who cared about them, but estimates were imprecise.

A Polysocial Approach in Exploring Racial and Ethnic Differences in Dementia and Cognitive Decline Among U.S. Older Adults: Health and Retirement Study

Background and Objectives

The racial or ethnic disparity in the burden of dementia exists among older adults in the United States, whereas gaps remain in understanding the synergic effect of multiple social determinants of health on diminishing this disparity. We aim to build a polysocial score for dementia and investigate the racial or ethnic difference in dementia risk among older persons with different polysocial score categories.

Research Design and Methods

In this prospective cohort study, we utilized longitudinal data from the Health and Retirement Study in the United States recruiting 6 945 participants aged ≥65 years who had data on 24 social determinants of health in 2006/2008. The dementia status of participants was measured by a modified version of the Telephone Interview of Cognitive Status. The stepwise Cox regression was applied to select social determinants of health associated with incident dementia to construct a polysocial score. The multivariable Poisson model and linear mixed model were utilized to investigate the associations between polysocial score and incident dementia and cognitive decline, respectively.

Results

Eight social determinants of health were used to build the polysocial score. Non-Hispanic Black older participants had a higher incidence rate (incidence rate difference [IRD] = 22.7; 95% confident interval [95% CI] = 12.7-32.8) than non-Hispanic White older adults in the low polysocial score, while this difference was substantially attenuated in the high polysocial score category (IRD = 0.5; 95% CI = -6.4 to -7.5). The cognitive decline of non-Hispanic older Black adults with high polysocial score was 84.6% slower (averaged cognitive decline: non-Hispanic White: -2.4 [95% CI = -2.5 to -2.3] vs non-Hispanic Black: -1.3 [95% CI = -1.9 to -0.8]) than that of non-Hispanic older White persons.

Discussion and Implications

These findings may help comprehensively understand and address racial and ethnic disparities in dementia risk and may be integrated into existing dementia prevention programs to provide targeted interventions for community-dwelling older adults with differentiated social disadvantages.

Mechanisms and Functions of the Cerebral-Cognitive Reserve in Patients with Alzheimer's Disease: A Narrative Review

BACKGROUND

The need for scientific knowledge about aging is predicated on the demand of modern society to extend the active life of a person. To maintain intellectual longevity, it is necessary to take into account not only the pathological, but also compensatory mechanisms that arise during aging. The cerebral-cognitive reserve (CCR) influences the rate of transition from pre-phenomenological stages to the clinical stage of the disease, thereby changing the prognosis of Alzheimer's disease (AD).

AIM

The aim of this work was to review meta-analyses from studies that have examined the principles and functions of the CCR in people with AD.

METHODS

The work included 83 scientific publications devoted to the issues of the CCR in neurodegenerative diseases such as AD. The Results and Discussion sections of this article provide reviews of the results of 12 meta-analyses published from 2012 to 2024 and selected from the PubMed and eLibrary databases using the following keywords in English and Russian: "cerebral reserve", "cognitive "reserve", and "Alzheimer's disease". The scope of the definition was not limited, since the goal here was to determine the terminological boundaries of the concepts of "cognitive reserve" and "single brain reserve".

RESULTS

The modern understanding of AD as a biological continuum covering the preclinical, prodromal, and clinical phases of the disease makes it possible to infer that insufficiency of protective factors underlies the progression of AD. The cognitive reserve is involved in the sanogenetic protective mechanism during neurodegeneration. The cognitive reserve is a theoretical concept that reflects modern research's understanding of how the integrative functioning of the brain (cerebral) and cognitive reserves extend the period of active intellectual longevity through energy-saving mechanisms. It considers these mechanisms as central to healthy mental activity and in slowing the progression of neurodegenerative diseases. At some point, an increase in excess interneuronal activity that reflects the hypercompensatory function of the reserve would accelerate the depletion of brain structures and contribute to clinical and psychopathological manifestations of AD.

CONCLUSION

The concept of the CCR puts the spotlight on the need to determine the compensatory indicators of cognitive deficit in AD, assess the architecture and volume of the reserve, and develop and follow protocols for its maintenance. It appears just as crucial to adopt measures to prevent the Reserve's depletion as early as at the preclinical stages of the disease. Elaborating protective and compensatory mechanisms that help to maintain the functional activity of the brain in conditions of neurodegeneration, that is, CCR, require further research and can form a conceptual basis for the prevention of AD, starting from the preclinical stages of the disease.

Trends on Prevalence, All-Cause Mortality, and Survival Status of Dementia Patients in Rural China Based on Pooling Analysis

Objectives

No study has reported secular trends in dementia prevalence, all-cause mortality, and survival status in rural China.

Methods

We established two cohorts (XRRCC1 and XRRCC2) in the same region of China, 17 years apart, to compare dementia prevalence, all-cause mortality, and survival status, and performed regression analysis to identify associated factors.

Results

Dementia prevalence was 3.49% in XRRCC1 and 4.25% in XRRCC2, with XRRCC2 showing a significantly higher prevalence (OR = 1.79, 95%CI: 1.2-2.65). All-cause mortality rates for dementia patients were 62.0% in XRRCC1 and 35.7% in XRRCC2. Mortality in the normal population of XRRCC2 decreased by 66% compared to XRRCC1, mainly due to improved survival rates in women with dementia. Dementia prevalence was positively associated with age >65, spouse-absent status, and stroke, and negatively associated with ≥6 years of education.

Conclusion

Dementia prevalence in rural China increased over 17 years, while mortality decreased. Major risk factors include aging, no spouse, and stroke, with higher education offering some protection.

An 11-Fold Higher Risk of Incident Mild Cognitive Impairment With Hispanic Ethnicity and Baseline Neuropsychiatric Symptoms

OBJECTIVE

Neuropsychiatric symptoms (NPSs) have been linked to cognitive decline. This study explored ethnic differences and the effects of baseline NPSs on incident mild cognitive impairment (MCI) among 386 Hispanic and non-Hispanic participants from the Texas Harris Alzheimer's Research Study.

METHODS

Data on NPSs from the Neuropsychiatric Inventory Questionnaire were available for all participants. Cox proportional hazards regression models were used to estimate the effect of ≥1 NPS at baseline and Hispanic ethnicity on incident MCI over a 7-year follow-up period.

RESULTS

NPSs at baseline were associated with incident MCI for Hispanic participants but not non-Hispanic participants. Being Hispanic with at least one NPS at baseline had an 11-times higher risk of incident MCI.

CONCLUSIONS

The Hispanic participants converted to MCI to a greater extent than the non-Hispanic participants. Only depressive symptoms increased the risk of MCI among non-Hispanics. Being of Hispanic ethnicity and having NPSs appeared to jointly increase the risk of progressing to MCI. To better understand the Alzheimer's disease continuum, further studies should explore other cultural, genetic, and medical risk factors influencing disease progression. Our findings strongly suggest the need to incorporate NPSs as outcomes of disease progression in future clinical trials involving Hispanic participants.

Mental health problems raise the odds of cognitive impairment in COVID-19 survivors

Background

COVID-19 survivors around the globe are suffering from mental health issues. While mental health problems can be an early warning sign of dementia, they may also increase the chances of developing the disease. In this study, we examined the mental health of COVID-19 survivors and mapped its associations with cognitive and demographic variables.

Method

COVID-19 survivors listed in the databases of three tertiary care hospitals in Kolkata were contacted sequentially. 376 willing patients were interviewed over the telephone. 99 COVID-19 patients and 31 matched controls participated in the in-person interviews that were arranged for a more detailed investigation. The participants were administered standardized tests that are widely used for the assessment of cognitive functioning and mental health status.

Result

64.89% of COVID-19 survivors reported a deterioration in physical functioning. 44.95% reported a decline in mental health, whereas 41.49% reported a drop in cognitive performance. Detailed investigations revealed that they had an increased risk of having depression, anxiety, and poor sleep quality by 91%, 68%, and 140%, respectively. 6.1% of the patients had mild cognitive impairment, and 4% had dementia. COVID-19 patients who had depression and anxiety were 8.6 and 19.4 times more likely to have cognitive decline, respectively. Compared to the matched controls, COVID-19 patients had greater depression (p<.001), anxiety (p<.001), stress (p =.003), and insomnia (p <.001). They also scored significantly lower on Addenbrooke's Cognitive Examination-III (p =.009) and Picture Naming Test (p =.005) and took significantly longer to complete Trail Making Test-A (p =.002).

Conclusion

COVID-19 survivors in this study had major mental health issues even one year after contracting the virus. They had significant cognitive deficits that might progress into dementia. Strict monitoring and systematic treatment plans should be implemented as soon as possible.

Knowledge, Awareness, and Perceived Threat Toward Alzheimer's Disease Among the Family Caregivers of Individuals with Chronic Physical Conditions in Bangladesh

Background

Alzheimer's disease (AD) is a growing public health concern affecting millions of individuals worldwide. This disease burden is exacerbated in countries like Bangladesh, where public awareness and knowledge about the condition remains limited.

Objective

This study aimed to assess the level of AD knowledge, awareness, and perceived threat among family caregivers of individuals with chronic physical conditions of Bangladesh.

Methods

A descriptive cross-sectional study was conducted among the caregivers of patients selected via convenience sampling in six public hospitals between October 2022 and March 2023. The data was collected via face-to-face interviews employing a semi-structured questionnaire that contained information about socio-demographic characteristics, personal experiences with AD, knowledge of AD, level of awareness regarding AD, and perceived threat toward AD.

Results

The findings revealed a poor knowledge of AD among the study participants. Regarding AD awareness, 52.5% considered memory loss in older individuals abnormal, 26.2% attributed AD to causes like black magic, psychological distress, or bad eyes. Regarding perceived threat, 60.2% wanted to assess their AD risk, while 68.2% disagreed with the likelihood of developing the disease. Multiple linear regression analysis revealed that age, place of residence, education, and employment status significantly contribute to AD knowledge scores.

Conclusions

This study highlights the urgent need for public education and awareness campaigns to address the knowledge gap and reduce stigmatization associated with AD in Bangladesh. Targeted efforts, particularly among older age groups and rural communities, can enhance understanding and improve the quality of care and support for AD patients and their caregivers.

Health literacy, but not memory, is associated with hippocampal connectivity in adults with low levels of formal education

INTRODUCTION

The influence of hippocampal connectivity on memory performance is well established in individuals with high educational attainment. However, the role of hippocampal connectivity in illiterate populations remains poorly understood.

METHODS

Thirty-five illiterate adults were administered a literacy assessment (Test of Functional Health Literacy in Adults [TOFHLA]), structural and resting state functional magnetic resonance imaging, and an episodic memory test (Free and Cued Selective Reminding Test). Illiteracy was defined as a TOFHLA score < 53. We evaluated the correlation between hippocampal connectivity at rest and both free recall and literacy scores.

RESULTS

Participants were mostly female (57.1%) and self-declared as being Black individuals (84.8%), with a median age of 50 years. The median TOFHLA literacy score was 28.0 [21.0; 42.5] out of 100 points and the median free recall score was 30.0 [26.2; 35] out of 48 points. The median gray matter volume of both the left and right hippocampi was 2.3 [2.1; 2.4] cm3. We observed a significant connectivity between both hippocampi and the precuneus and the ventral medial prefrontal cortex. The right hippocampal connectivity positively correlated with the literacy scores (β = 0.58, P = 0.008). There was no significant association between episodic memory and hippocampal connectivity. Neither memory nor literacy scores correlated with hippocampal gray matter volume.

DISCUSSION

Low literacy levels correlated with hippocampal connectivity in illiterate adults. The lack of association with memory scores might be associated with low brain reserve in this sample.

Highlights

A significant link was found between health literacy and hippocampal connectivity.Enhanced hippocampus- ventromedial prefrontal cortex connectivity suggests potential cognitive reserve improvement.Higher cognitive reserve may protect against hippocampal atrophy and neurodegeneration.Health literacy improvements could help prevent cognitive impairment in illiterate populations.Study highlights importance of considering structural racism in brain connectivity research.

Midlife Residential Greenness and Late-Life Cognitive Decline among Nurses' Health Study Participants

BACKGROUND

Midlife residential exposure to greenspace may slow cognitive decline by increasing opportunities for physical activity and social connection, restoring attention, or reducing stress or adverse environmental exposures. However, prospective studies on the association between greenness and cognitive decline are sparse.

OBJECTIVE

We investigated the prospective association between greenness at midlife and cognitive decline later in life. We explored effect measure modification by apolipoprotein E (APOE)-ɛ4 carrier status, neighborhood socioeconomic status (NSES), and rural/urban regions.

METHODS

The Nurses' Health Study (N = 121,700 ) started in 1976 with married female nurses, 30-55 years of age, located across 11 US states. We examined 16,962 nurses who were enrolled in a substudy starting in 1995-2001 (mean age = 74 y ) through 2008. We assessed average summer residential greenness in a 270 -m buffer using Landsat Normalized Difference Vegetation Index data from 1986-1994. Starting in 1995-2001, participants underwent up to four repeated measures of five cognitive tests. A global composite score was calculated as the average of all z -scores for each task to evaluate overall cognition. We used linear mixed models to evaluate the association of average greenness exposure at midlife with cognitive decline in later life, adjusted for age, education, NSES, and depression.

RESULTS

In adjusted models, higher midlife greenness exposure [per interquartile range (IQR): 0.18] was associated with a 0.004-unit (95% CI: 0.001, 0.006) slower annual rate of cognitive decline. For comparison, we found that 1 year of age is related to a - 0.006 mean annual difference for global cognition in the full sample; thus, higher midlife greenness appeared equivalent to slowing cognitive decline by ∼ 8 months. In analysis exploring gene-environment interactions, we found that among APOE-ɛ4 carriers, an IQR increase in greenness was associated with a rate of decline that was slower by 0.01 units of global composite score (95% CI: 0.0004, 0.02). This association was attenuated among APOE-ɛ4 noncarriers. We did not observe associations between greenness and baseline or annual rate of cognitive decline of verbal memory.

DISCUSSION

Higher midlife greenness exposure is associated with slower cognitive decline later in life. Future research is necessary to confirm these findings. https://doi.org/10.1289/EHP13588.

Active and Passive Smoking as Catalysts for Cognitive Impairment in Rural Indonesia: A Population-based Study

Objectives

Research indicates that active smokers are at risk of cognitive impairment. However, the correlation between chronic passive smoking and the risk of cognitive impairment remains underexplored. This study aimed to determine the association between smoking, passive smoking, and cognitive impairment and examined the dose-response effect.

Methods

This population-based two-year survey was conducted in four rural public health centers from 2021 to 2023 in Central Java, Indonesia, each center caters to approximately 30 000 people. The participants were selected using simple random sampling from the health center visitors aged 30-60 years. Smoking and passive smoking were determined by self-assessment. Mini-Mental State Examination was used to evaluate cognitive impairment. The potential impact of confounding variables such as lifestyle, sociodemographic factors, and chronic diseases were considered and excluded during statistical analysis.

Results

The participants were 409 individuals aged 30-60 years. The majority were men (264; 64.5%). Among them, 308 (75.3%) were active smokers, 271 (66.3%) were passive smokers, and 138 (33.7%) were not exposed to tobacco smoke. There was a significant relationship between cognitive impairment and increasing pack years of active smoking. The highest and most significant risk was observed in those who smoked ≥ 20 pack-years with an adjusted odds ratio (aOR) of 1.61 and 95% CI: 0.98-2.31. Passive smokers had a slightly lower risk of cognitive impairment than those who did not smoke and never smoked (aOR = 2.01; 95% CI: 1.37-2.70). They were comparable with OR of 10-19 pack-years total exposure to active smoking (aOR = 1.86; 95% CI: 1.24-2.42).

Conclusions

There was a dose-response relationship between smoking and cognitive impairment with a significant effect on ≥ 20 pack-years of exposure. Passive smoking also indicated a significant risk of cognitive impairment equivalent to an estimated 10-19 pack-years of active smoking.

The impact of educational attainment on mental health: A Causal Assessment from the UKB and FinnGen Cohorts

Observational studies report inverse associations between educational attainment and depression/anxiety risks, but confounding hinders causal inference. This study aimed to assess potential causal relationships using Mendelian randomization (MR). Two-sample MR analysis was conducted using genetic instruments for education, smoking, body mass index, and physical activity from published genome-wide association studies. Depression and anxiety data came from the UK Biobank ([UKB] 117,782 individuals) and FinnGen (215,644 individuals) cohorts. Inverse variance weighted regression determined associations between exposures and mental health outcomes. Increased educational attainment was causally associated with reduced risks of depression (odds ratio [OR] = 0.99 per year, 95% confidence interval [CI]: 0.990-0.996, P < .001) and anxiety (OR = 0.99, CI: 0.98-0.991, P < .001) in both cohorts. Smoking initiation conferred higher risks of depression (UKB OR = 1.05, CI: 1.03-1.06, P < .001; FinnGen OR = 1.20, CI: 1.10-1.32, P < .001) and anxiety (FinnGen only, OR = 1.10, CI: 1.01-1.21, P < .05). Likewise, maternal smoking history associated with greater depression (UKB OR = 1.15, CI: 1.10-1.35, P = .027) and anxiety susceptibility (FinnGen OR = 3.02, CI: 1.67-5.46, P = .011). Higher body mass index elevated depression risk in both cohorts. Physical activity showed no clear associations. This MR study provides evidence that education may causally reduce mental health disorder risk. Smoking, obesity, and low activity appear detrimentally linked to depression and anxiety. Improving access to education could offer effective strategies for lowering population psychiatric burden.

Prevalence and risk factors for Alzheimer's disease and related dementias in Ghana: Evidence from a cross-sectional population-based study

Alzheimer's disease and Related Dementia (ADRD) is a growing concern for low- and middle-income countries. Yet, studies on the prevalence and risk factors for dementia in sub-Saharan Africa are limited. This study estimated the prevalence and identified the risk factors for ADRD in Ghana. A cross-sectional design involving 384 participants aged 60 years or more completed the Brief Community Screening Instrument for Dementia (CSID) with an additional set of questions on risk factors. The prevalence of dementia was 16% (62/384). Age (AOR = 1.031 (95% CI 1.002-1.061, p=0.035), education (AOR = 0.689 (95% CI 0.517-0.919, p=0.011), and employment (AOR = 0.320 (95% CI 0.149-0.685, p=0.004) were associated with dementia. Also, "experience of stressful life event from age 16-64" (AOR = 1.325 (95% CI 1.034-1.698, p=0.024), "experience of stressful life event from age 65+" (AOR = 1.258 (95% CI 1.024-1.546, p=0.042), and "activities of daily living" (AOR = 0.925 (95% CI 0.868-0.986, p=0.037) identified as risk factors of dementia. The burden of ADRD was high. Urgent actions are needed to address this problem. There is a possibility that the burden of dementia may have been overestimated because of the study instrument. Findings should be interpreted in light of this limitation.

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.

Experimental laboratory models as tools for understanding modifiable dementia risk

Experimental laboratory research has an important role to play in dementia prevention. Mechanisms underlying modifiable risk factors for dementia are promising targets for dementia prevention but are difficult to investigate in human populations due to technological constraints and confounds. Therefore, controlled laboratory experiments in models such as transgenic rodents, invertebrates and in vitro cultured cells are increasingly used to investigate dementia risk factors and test strategies which target them to prevent dementia. This review provides an overview of experimental research into 15 established and putative modifiable dementia risk factors: less early-life education, hearing loss, depression, social isolation, life stress, hypertension, obesity, diabetes, physical inactivity, heavy alcohol use, smoking, air pollution, anesthetic exposure, traumatic brain injury, and disordered sleep. It explores how experimental models have been, and can be, used to address questions about modifiable dementia risk and prevention that cannot readily be addressed in human studies. HIGHLIGHTS: Modifiable dementia risk factors are promising targets for dementia prevention. Interrogation of mechanisms underlying dementia risk is difficult in human populations. Studies using diverse experimental models are revealing modifiable dementia risk mechanisms. We review experimental research into 15 modifiable dementia risk factors. Laboratory science can contribute uniquely to dementia prevention.

Specification curve analysis to identify heterogeneity in risk factors for dementia: findings from the UK Biobank

BACKGROUND

In 2020, the Lancet Commission identified 12 risk factors as priorities for prevention of dementia, and other studies identified APOE e4/e4 genotype and family history of Alzheimer's disease strongly associated with dementia outcomes; however, it is unclear how robust these relationships are across dementia subtypes and analytic scenarios. Specification curve analysis (SCA) is a new tool to probe how plausible analytical scenarios influence outcomes.

METHODS

We evaluated the heterogeneity of odds ratios for 12 risk factors reported from the Lancet 2020 report and two additional strong associated non-modifiable factors (APOE e4/e4 genotype and family history of Alzheimer's disease) with dementia outcomes across 450,707 UK Biobank participants using SCA with 5357 specifications across dementia subtypes (outcomes) and analytic models (e.g., standard demographic covariates such as age or sex and/or 14 correlated risk factors).

RESULTS

SCA revealed variable dementia risks by subtype and age, with associations for TBI and APOE e4/e4 robust to model specification; in contrast, diabetes showed fluctuating links with dementia subtypes. We found that unattributed dementia participants had similar risk factor profiles to participants with defined subtypes.

CONCLUSIONS

We observed heterogeneity in the risk of dementia, and estimates of risk were influenced by the inclusion of a combination of other modifiable risk factors; non-modifiable demographic factors had a minimal role in analytic heterogeneity. Future studies should report multiple plausible analytic scenarios to test the robustness of their association. Considering these combinations of risk factors could be advantageous for the clinical development and evaluation of novel screening models for different types of dementia.