A pathway from low socioeconomic status to dementia in Japan: results from the Toyama dementia survey

Associations of socioeconomic status and healthy lifestyle with incident dementia and cognitive decline: two prospective cohort studies

Background

Little is known about the complex associations of socioeconomic status (SES) and healthy lifestyle with cognitive dysfunction.

Methods

Using data from the Health and Retirement Study (HRS) [2008-2020] and the English Longitudinal Study of Ageing (ELSA) [2004-2018], SES was constructed by latent class analysis using education level, total household income and wealth. Overall healthy lifestyle was derived using information on never smoking, low to moderate alcohol consumption (drinks/day: (0, 1] for women and (0, 2] for men), top tertile of physical activity, and active social contact.

Findings

A total of 12,437 and 6565 participants from the HRS and ELSA were included (40.8% and 46.0% men and mean age 69.3 years and 65.1 years, respectively). Compared with participants of high SES, those of low SES had higher risk of incident dementia (hazard ratio 3.17, 95% confidence interval 2.72-3.69 in the HRS; 1.43, 1.09-1.86 in the ELSA), and the proportions mediated by overall lifestyle were 10.4% (7.3%-14.6%) and 2.7% (0.5%-14.0%), respectively. Compared with participants of high SES and favorable lifestyle, those with low SES and unfavorable lifestyle had a higher risk of incident dementia (4.27, 3.40-5.38 in the HRS; 2.02, 1.25-3.27 in the ELSA) and accelerated rate of global cognitive decline (β = -0.058 SD/year; 95% CI: -0.073, -0.043 in the HRS; β = -0.049 SD/year; 95% CI: -0.063, -0.035 in the ELSA).

Interpretation

Unhealthy lifestyle only mediated a small proportion of the socioeconomic inequality in dementia risk in both US and UK older adults.

Funding

This work was supported by grants from the National Natural Science Foundation of China (82088102 and 82370819), the National Key R&D Program of China (2023YFC2506700), the Shanghai Municipal Government (22Y31900300), the Shanghai Clinical Research Center for Metabolic Diseases (19MC1910100), the Innovative Research Team of High-Level Local Universities in Shanghai, the Special Project for Clinical Research in Health Industry of Shanghai Municipal Health Commission (202340084), and Ruijin Hospital Youth Incubation Project (KY20240805). Y.X. is supported by the National Top Young Talents program.

The effect of diabetes in the multifaceted relationship between education and cognitive function

BACKGROUND

Education has been shown to be positively associated with cognitive performance. However, the pathways via lifestyle-related disease through which education is related to cognitive performance have not been sufficiently explored. Diabetes is an important lifestyle-related disease with increasing prevalence worldwide. Low education is associated with an increased risk of developing diabetes, while diabetes may also lead to a deterioration in cognitive performance. This study aims to explore if the associations between education and cognitive function is mediated by the diabetes status among older adults.

METHODS

The data utilized in this study were derived from the first two waves of the Dutch Lifelines Cohort Study (2006-2015). The analyzed sample included 26,131 individuals aged 50 years or above at baseline. The baseline assessment included measurements of educational attainment (exposure) and the potential mediator diabetes. The outcome of cognitive function was assessed using age-standardized reaction times from the psychomotor function and attention tasks, as measured by the Cogstate Brief Battery. The Cogstate Brief Battery was only conducted at the follow-up assessment, not at the baseline assessment. Faster reaction times correspond to higher cognitive performance. The study employed linear and logistic regression models, in addition to a causal mediation approach which estimated the average causal mediation effect (ACME).

RESULTS

Higher education was associated with a lower risk of diabetes (b= -0.1976, 95%CI= -0.3354; -0.0597) compared to low or middle education as well as with faster reaction times (b= -0.2023, 95%CI= -0.2246; -0.1798), implying better cognitive function. Diabetes was associated with slower reaction times (b = 0.0617, 95%CI = 0.0162; 0.1072). Most importantly, the mediation approach identified a significant indirect effect of education on cognitive function via the diabetes status (ACME= -0.00061, 95%CI= -0.00142; -0.00011).

DISCUSSION

The findings emphasize the potentially importance of diabetes in explaining the role of education in promoting healthy cognitive function and mitigating the risk of cognitive decline. Early detection and treatment of diabetes may be particularly beneficial for individuals with low or middle levels of education in order to maintain good levels of cognitive function.

The iceberg of dementia risk: empirical and conceptual arguments in favor of structural interventions for brain health

While pharmacological interventions for dementia struggle to demonstrate improved outcomes for patients and at-risk populations, non-pharmacological lifestyle interventions have been proposed as a tool to achieve dementia risk reduction. In this review, it is argued that lifestyle modification alone is a surface-level intervention from the point of view of fair and far-reaching dementia prevention. Below the tip of this "iceberg of dementia risk," there are living conditions and social structures that represent deeper contributions to risk in the population. It is argued that alongside lifestyle modification, activist research and structural interventions are needed to make our society fairer and more dementia-resilient.

Sex difference in the associations of socioeconomic status, cognitive function and brain volume with dementia in old adults: Findings from the OASIS study

Background

Sex differences in the association of cognitive function and imaging measures with dementia have not been fully investigated while sex-based investigation of dementia has been discussed. Understanding sex differences in the dementia-related socioeconomic, cognitive, and imaging measurements is important for uncovering sex-related pathways to dementia and facilitating early diagnosis, family planning, and cost control.

Methods

We selected data from the Open Access Series of Imaging Studies with longitudinal measurements of brain volumes on 150 individuals aged 60 to 96 years. Dementia status was determined using the Clinical Dementia Rating (CDR) scale, and Alzheimer's disease was diagnosed as a CDR of ≥ 0.5. Generalized estimating equation models were used to estimate the associations of socioeconomic, cognitive and imaging factors with dementia in men and women.

Results

Lower education affected dementia more in women than in men. Age, education, Mini-Mental State Examination (MMSE), and normalized whole-brain volume (nWBV) were associated with dementia in women whereas only MMSE and nWBV were associated with dementia in men. Lower socioeconomic status was associated with a reduced estimated total intracranial volume in men, but not in women. Ageing and lower MMSE scores were associated with reduced nWBV in both men and women.

Conclusions

The association between education and prevalence of dementia differs in men and women. Women may have more risk factors for dementia than men.

Predictors of the rate of cognitive decline in older adults using machine learning

BACKGROUND

The longitudinal rates of cognitive decline among aging populations are heterogeneous. Few studies have investigated the possibility of implementing prognostic models to predict cognitive changes with the combination of categorical and continuous data from multiple domains.

OBJECTIVE

Implement a multivariate robust model to predict longitudinal cognitive changes over 12 years among older adults and to identify the most significant predictors of cognitive changes using machine learning techniques.

METHOD

In total, data of 2733 participants aged 50-85 years from the English Longitudinal Study of Ageing are included. Two categories of cognitive changes were determined including minor cognitive decliners (2361 participants, 86.4%) and major cognitive decliners (372 participants, 13.6%) over 12 years from wave 2 (2004-2005) to wave 8 (2016-2017). Machine learning methods were used to implement the predictive models and to identify the predictors of cognitive decline using 43 baseline features from seven domains including sociodemographic, social engagement, health, physical functioning, psychological, health-related behaviors, and baseline cognitive tests.

RESULTS

The model predicted future major cognitive decliners from those with the minor cognitive decline with a relatively high performance. The overall AUC, sensitivity, and specificity of prediction were 72.84%, 78.23%, and 67.41%, respectively. Furthermore, the top 7 ranked features with an important role in predicting major vs minor cognitive decliners included age, employment status, socioeconomic status, self-rated memory changes, immediate word recall, the feeling of loneliness, and vigorous physical activity. In contrast, the five least important baseline features consisted of smoking, instrumental activities of daily living, eye disease, life satisfaction, and cardiovascular disease.

CONCLUSION

The present study indicated the possibility of identifying individuals at high risk of future major cognitive decline as well as potential risk/protective factors of cognitive decline among older adults. The findings could assist in improving the effective interventions to delay cognitive decline among aging populations.

Socioeconomic Inequalities in Cognitive Functioning Only to a Small Extent Attributable to Modifiable Health and Lifestyle Factors in Individuals Without Dementia

BACKGROUND

There are socioeconomic inequalities in dementia risk. Underlying pathways are not well known.

OBJECTIVE

To investigate whether modifiable health and lifestyle factors for brain health mediate the association of socioeconomic status (SES) and cognitive functioning in a population without dementia.

METHODS

The "LIfestyle for BRAin health" (LIBRA) score was computed for 6,203 baseline participants of the LIFE-Adult-Study. LIBRA predicts dementia in midlife and early late life, based on 12 modifiable factors. Associations of SES (education, net equivalence income, and occupational status) and LIBRA with cognitive functioning (composite score) were investigated using adjusted linear regression models. Bootstrapped structural equation modelling (SEM) was used to investigate whether LIBRA mediated the association of SES and cognitive functioning.

RESULTS

Participants were M = 57.4 (SD = 10.6, range: 40-79) years old; 50.3% were female. Both, SES (Wald: F(2)=52.5, p < 0.001) and LIBRA (Wald: F(1)=5.9, p < 0.05) were independently associated with cognitive functioning; there was no interaction (Wald: F(2)=2.9, p = 0.060). Lower SES and higher LIBRA scores indicated lower cognitive functioning. LIBRA partially mediated the association of SES and cognitive functioning (IE: =0.02, 95% CI [0.02, 0.03], p < 0.001). The proportion mediated was 12.7%.

CONCLUSION

Differences in cognitive functioning due to SES can be partially attributed to differences in modifiable health and lifestyle factors; but to a small extent. This suggests that lifestyle interventions could attenuate socioeconomic inequalities in cognitive functioning. However, directly intervening on the social determinants of health may yield greater benefits for dementia risk reduction.

Contribution of smoking towards the association between socioeconomic position and dementia: 32-year follow-up of the Whitehall II prospective cohort study

Background

There is consistent evidence of social inequalities in dementia but the mechanisms underlying this association remain unclear. We examined the role of smoking in midlife in socioeconomic differences in dementia at older ages.

Methods

Analyses were based on 9951 (67% men) participants, median age 44.3 [IQR=39.6, 50.3] years at baseline in 1985-1988, from the Whitehall II cohort study. Socioeconomic position (SEP) and smoking (smoking status (current, ex-, never-smoker), pack years of smoking, and smoking history score (combining status and pack-years)) were measured at baseline. Counterfactual mediation analysis was used to examine the contribution of smoking to the association between SEP and dementia.

Findings

During a median follow-up of 31.6 (IQR 31.1, 32.6) years, 628 participants were diagnosed with dementia and 2110 died. Analyses adjusted for age, sex, ethnicity, education, and SEP showed smokers (hazard ratio [HR] 1.36 [95% CI 1.10-1.68]) but not ex-smokers (HR 0.95 [95% CI 0.79-1.14]) to have a higher risk of dementia compared to never-smokers; similar results for smoking were obtained for pack-years of smoking and smoking history score. Mediation analysis showed low SEP to be associated with higher risk of dementia (HRs between 1.97 and 2.02, depending on the measure of smoking in the model); estimate for the mediation effect was 16% for smoking status (Indirect Effect HR 1.09 [95% CI 1.03-1.15]), 7% for pack-years of smoking (Indirect Effect HR 1.03 [95% CI 1.01-1.06]) and 11% for smoking history score (Indirect Effect HR 1.06 [95% CI 1.02-1.10]).

Interpretation

Our findings suggest that part of the social inequalities in dementia is mediated by smoking.

Funding

NIH.

Association of social determinants of health with frailty, cognitive impairment, and self-rated health among older adults

Background and objectives

Recently, the role of social determinants of health on frailty and dementia has received increased attention. The aim of the present study is to explore the association of social determinants on cognitive impairment, frailty, and self-rated health. As health is influenced by many factors, we also examine other health determinants including lifestyle, health seeking behaviour, socio-demographics, and multimorbidity in the analysis.

Research design and methods

Cross-sectional analysis of the Healthy Older People Everyday (HOPE) study in Singapore was carried out on 998 older adults above the age of 65. We used forward stepwise multivariable logistic and linear regression analyses to assess the association of five health determinants (social determinants, lifestyle, health seeking behaviour, socio-demographics and multimorbidity) on frailty, cognitive impairment, and self-rated health.

Results

Mean age of participants was 71.1 ± 0.2 years; 154 (15.4%) were cognitively impaired; 430 (43.1%) were pre-frail or frail; mean self-rated health was 80.4 ± 15.6. Social determinants contributed between 29% to 57% of the overall variation found in the full model with all five health determinants adjusted for. Participants with higher education had significantly lower odds of cognitive impairment and frailty. Leisure physical activity was significantly associated with lower odds of frailty and cognitive impairment, and better self-rated health.

Discussion and implications

Understanding the dynamics of different health determinants is crucial to protect the vulnerable in an ageing population. Our study highlights the need for a multidimensional, multidisciplinary and multisectoral approach in the prevention of frailty, cognitive impairment, and associated disability.

Avoiding Over-Reliance on Multi-Domain Interventions for Dementia Prevention

Given the unknown therapeutic value of targeting Alzheimer's disease pathology and the discovery of robust risk factors for dementia, non-pharmacological risk reduction (RR) is increasingly offered as an alternative to targeting Alzheimer's disease pathology. While RR will surely be a useful tool to make public health gains, we propose solutions to three possible issues with over-reliance on multi-domain interventions to achieve RR: limited individual impact, an exclusive focus on later life, and overlooking social determinants of dementia. We argue in favor of a broader debate within the research community and greater society about how different therapeutic avenues should be explored.

Psychosocial and Trauma-Related Stress and Risk of Dementia: A Meta-Analytic Systematic Review of Longitudinal Studies

Stress has deleterious effects on brain health and yet, the prognostic value of psychosocial stress regarding the most common types of dementias, including Alzheimer disease, is still unclear. The primary aim of this systematic review was to explore the association between psychosocial stress and late onset dementia. We classified 24articles from Medline, PsycINFO, CINAHL, and Web of Science, as pertaining toxic categories of psychosocial and trauma-related stress (low socio-economic status [SES] related inequalities, marital status, posttraumatic stress disorder, work stress, "vital exhaustion" [VE], and, combined stressors). Using the Quality of Prognosis Studies in Systematic Reviews tool, we judged the quality of evidence to be low. This systematic review provided some non-robust, yet suggestive evidence that the above psychosocial types of stress are associated with increased risk of dementia in later life. Future robust, longitudinal studies with repeated validated measures of psychosocial stress and dementiaare required to strengthen or refute these findings.

Future projections of the prevalence of dementia in Japan: results from the Toyama Dementia Survey

BACKGROUND

This study aimed to make future projections of the nationwide prevalence of dementia in Japan using the prevalence of dementia from the Toyama Dementia Survey and population projections.

METHODS

We performed linear regression analysis using the prevalence of dementia by sex and age in 1985, 1990, 1996, 2001, and 2014 from the Toyama Dementia Survey to calculate the estimated future prevalence by sex and age. The estimated prevalence was then multiplied by the estimated future population of people aged 65 years and older by sex and age in each of the 47 prefectures from 2020 to 2045 and added together to calculate the total number of people with dementia. The estimated future prevalence of dementia was calculated by dividing the calculated number of people with dementia by the estimated future population of people aged 65 years and older in each of the 47 prefectures. In addition, the estimated future prevalence of dementia in each of the 47 prefectures from 2020 to 2045 was presented on a map of Japan and grayscale-coded in four levels.

RESULTS

In 2020, the estimated future prevalence of dementia did not exceed 20% in any prefecture, but in 2025, five prefectures, mainly rural prefectures, had projected rates exceeding 20%. In 2030, the prevalence rate is projected to exceed 20% nationwide, and by 2035, the rate will exceed 25% in 42 prefectures. In 2045, all prefectures excluding Tokyo are projected to have a dementia prevalence rate exceeding 25%, and the rate will exceed 30% in 12 of 47 prefectures.

CONCLUSIONS

Over the next 25 years, the prevalence of dementia in people older than 65 years is projected to exceed 25% nationwide, including metropolitan areas.

Socioeconomic inequalities in dementia risk among a French population-based cohort: quantifying the role of cardiovascular health and vascular events

This study aimed to investigate the role of cardiovascular health (CVH) and vascular events as potential contributors to socioeconomic inequalities in dementia using causal mediation analyses. We used data from the Three-City Cohort, a French population-based study with 12 years of follow-up, with active search of dementia cases and validated diagnosis. Individual socioeconomic status was assessed using education, occupation and income. A CVH score as defined by the American Heart Association and incident vascular events were considered separately as mediators. We performed multi-level Cox proportional and Aalen additive hazard regression models to estimate the total effects of socioeconomic status on dementia risk. To estimate natural direct and indirect effects through CVH and vascular events, we applied two distinct weighting methods to quantify the role of CVH and vascular events: Inverse Odds Ratio Weighting (IORW) and Marginal Structural Models (MSM) respectively. Among 5581 participants, the risk of dementia was higher among participants with primary education (HR 1.60, 95%CI 1.44–1.78), blue-collar workers (HR 1.62, 95%CI 1.43–1.84) and with lower income (HR 1.23, 95%CI 1.09–1.29). Using additive models, 571 (95% CI 288–782) and 634 (95% CI 246–1020) additional cases of dementia per 100 000 person and year were estimated for primary education and blue-collar occupation, respectively. Using IORW, the CVH score mediate the relationship between education or income, and dementia (proportion mediated 17% and 26%, respectively). Yet, considering vascular events as mediator, MSM generated indirect effects that were smaller and more imprecise. Socioeconomic inequalities in dementia risk were observed but marginally explained by CVH or vascular events mediators.

Association between marital status and cognitive function in Japan: results from the Toyama Dementia Survey

BACKGROUND

This study aims to clarify the association between marital status and dementia in Japan, adjusting for socioeconomic, lifestyle, and lifestyle-related disease factors.

METHODS

Data from the Japanese Toyama Dementia Survey were used. Individuals aged ≥65 years living in Toyama Prefecture were randomly selected, and 1171 participants were analysed, with a sampling rate of 0.5%. The participants' marital status, socioeconomic status, lifestyle factors, and lifestyle-related diseases were assessed. The odds ratio (OR) of marital status for each lifestyle factor and medical histories were calculated by logistic regression analysis. The OR of marital status for dementia was also calculated by logistic regression analysis.

RESULTS

The prevalence of dementia was 7.4% for married, and 20.6% for non-married participants. Non-married participants showed a higher prevalence of a history of stroke than married participants. The age- and sex-adjusted OR of marital status for dementia was 1.99 (95% confidence interval (CI) 1.24-3.18) for non-married compared with married participants. Following variable adjustments, the OR for dementia was higher for non-married participants (adjusted OR 1.71; 95% CI 1.03-2.85).

CONCLUSIONS

Non-marital status was an independent risk factor for dementia in Japan even after adjusting for socioeconomic, lifestyle, and lifestyle-related disease factors. Non-married people were more likely to have dementia because of their history of stroke.

Effect of Social Determinants of Health on Cognition and Risk of Alzheimer Disease and Related Dementias

Social determinants of health are the conditions in which people are born, work, live, and age and the wider set of forces and systems that shape the conditions of daily life. They affect every area of life, particularly health and health care. There is increasing focus on modifiable factors that affect cognition and risk of Alzheimer disease and related dementias (ADRDs). This article examines the impact of various social determinants of health, which are potentially reversible, on the incidence, prevalence, and risk of ADRDs and cognition. Various social determinants of health affect cognition and risk of ADRDs. Lower socioeconomic status (SES) and less education are associated with a higher incidence of ADRDs, whereas higher SES and education level appear to be protective, leading to a deceleration of time to diagnosis. In terms of employment, manual labor is associated with a higher risk of ADRDs. Higher body mass index in midlife and a decreasing body mass index in old age are associated with a higher risk of ADRDs. Furthermore, lower food security in early and late life is associated with a higher risk of ADRD diagnosis. Neighborhoods that are economically disadvantaged with fewer physical resources are associated with a higher risk of ADRDs. Higher levels of social engagement have a protective effect on diagnosis of ADRDs. Higher levels of stress are associated with a higher likelihood of developing ADRDs. Early-life adversity is associated with an increased risk of ADRDs, and further work in this area will be illuminating. Racial discrimination also leads to higher risk of ADRDs through the direct effect of discrimination and indirectly through lower SES, educational level, employment, and residential segregation. With an aim of reducing of ADRDs, future work in enhancing education, improving socioeconomic conditions, work, and neighborhood environments, and eliminating racial discrimination could potentially have a drastic impact.

Impact of individual and neighborhood dimensions of socioeconomic status on the prevalence of mild cognitive impairment over seven-year follow-up

Objectives: There is strong evidence about the association between low socioeconomic status (SES) and higher risk of dementia. However, it has not been conveniently addressed so far the role of SES on the incidence of mild cognitive impairment (MCI). This study examines the impact of individual and neighbourhood dimensions of SES, as well as their interaction, on the risk of developing MCI in a sample of older adults.Method: Data from the Vallecas Project cohort, an ongoing community-based longitudinal study for early detection of cognitive impairment and dementia, were used to build two indices of SES namely individual and neighbourhood, as well as a global SES as a combination of both, and to investigate their effects on MCI conversion by means of a multivariate-adjusted Cox proportional hazard model.Results: A total of 1180 participants aged 70 years and older were enrolled in this study. Of these, 199 cases of MCI (16.9%) were diagnosed at any point of the follow-up. The individual and neighbourhood dimensions of SES played different roles in the dynamics of the MCI occurrence through aging. Most importantly, the risk of developing MCI was almost double for lower SES quartiles when compared to the highest one.Conclusion: The incidence of MCI in older adults was related to both individual characteristics and socioeconomic context. Public health strategies should be holistic and focus not only on promoting the classical individual preventive measures, but also on reducing social inequalities to foster healthy aging and reduce dementia burden.

Depression as a Mediator of the Association Between Wealth Status and Risk of Cognitive Impairment and Dementia: A Longitudinal Population-Based Cohort Study

BACKGROUND

Wealth and income are potential modifiable risk factors for dementia, but whether wealth status, which is composed of a combination of debt and poverty, and assessed by wealth and income, is associated with cognitive impairment among elderly adults remains unknown.

OBJECTIVE

To examine the associations of different combinations of debt and poverty with the incidence of dementia and cognitive impairment without dementia (CIND) and to evaluate the mediating role of depression in these relationships.

METHODS

We included 15,565 participants aged 51 years or older from the Health and Retirement Study (1992-2012) who were free of CIND and dementia at baseline. Dementia and CIND were assessed using either the modified Telephone Interview for Cognitive Status (mTICS) or a proxy assessment. Cox models with time-dependent covariates and mediation analysis were used.

RESULTS

During a median of 14.4 years of follow-up, 4,484 participants experienced CIND and 1,774 were diagnosed with dementia. Both debt and poverty were independently associated with increased dementia and CIND risks, and the risks were augmented when both debt and poverty were present together (the hazard ratios [95% confidence intervals] were 1.35 [1.08-1.70] and 1.96 [1.48-2.60] for CIND and dementia, respectively). The associations between different wealth statuses and cognition were partially (mediation ratio range: 11.8-29.7%) mediated by depression.

CONCLUSION

Debt and poverty were associated with an increased risk of dementia and CIND, and these associations were partially mediated by depression. Alleviating poverty and debt may be effective for improving mental health and therefore curbing the risk of cognitive impairment and dementia.

What does (low) education mean in terms of dementia risk? A systematic review and meta-analysis highlighting inconsistency in measuring and operationalising education

Low education is considered an important modifiable risk factor for dementia worldwide, despite the lack of a formal consensus definition of low education. The primary aim of this systematic review was to document and address the inconsistency in measuring and operationalising education in dementia studies. A secondary aim was to consider the dose of education required to reduce dementia risk. The protocol was registered at PROSPERO with registration ID CRD42018096168. CINAHL, Cochrane, PsycInfo, and Pubmed databases were searched using terms related to education, dementia and/or MCI, and incidence. Studies were eligible for inclusion if a risk ratio for education and any dementia, Alzheimer's Disease (AD), Vascular Dementia (VaD) or Mild Cognitive Impairment (MCI) was reported in a population cognitively healthy at baseline. Sample sizes for 65 studies meeting selection criteria ranged from 152 to 12,881, representing populations from 24 countries. Risk of bias, assessed using a tool designed specifically for dementia risk studies, was found to be medium or low for all studies. There were 23 continuous, 29 dichotomous, and 31 categorical operationalisations of education reported. Random effects meta-analyses from continuous operationalisations suggested each year of education reduced risk by eight percent for AD (95% CI:5-12%) and seven percent for any dementia (95% CI:6-9%). Dichotomous operationalisations indicated an increased risk for low education of 45% (95% CI:29-63%) for any dementia and 85% (95% CI:56-118%) for AD, however definitions of low education were heterogeneous, ranging from zero to 12 years. There were too few studies to produce summary ratios for VaD or MCI. We conclude that, while the evidence of an association between low education and dementia incidence is robust, inconsistency in the definition, measurement and operationalisation of education hinders the translation of this evidence into practical policy recommendations to reduce dementia risk.

Association between self-reported hearing loss and low socioeconomic status in Japan: findings from the Toyama dementia survey

Background

Age-related hearing loss reduces the quality of life in older adults. Low socioeconomic status (SES) has been reported as a risk factor for hearing loss, although this has not been verified in Japan. This study aimed to assess the association between low SES and hearing loss, excluding people with dementia, in Japan.

Methods

Data from the Toyama Dementia Survey, Japan, were used. Overall, 126 patients with hearing loss and 913 unimpaired controls were identified. Participants’ presentation of dementia, self-reported hearing loss, history of medically diagnosed disease (hypertension, hyperlipidemia, diabetes, stroke, or angina pectoris/cardiovascular disease), lifestyle factors (alcohol consumption and smoking), and SES (educational attainment and occupation) were assessed. Any association between low SES and hearing loss was investigated using logistic regression analysis.

Results

The odds ratio (OR) for hearing loss was higher for participants with low educational attainment than for those with high educational attainment (age- and sex-adjusted OR 3.08; 95% confidence intervals [CI], 1.51–6.28). After adjusting the models for SES, lifestyle factors, and medical history, the OR increased from 2.90 (95% CI, 1.40–6.01) to 3.43 (95% CI, 1.62–7.27). The OR for hearing loss for participants with blue-collar jobs compared with that of participants with white-collar jobs was not significant (age- and sex-adjusted OR, 1.45; 95% CI, 0.93–2.25). Older age and a history of angina pectoris or cardiovascular disease were found to increase the risk of hearing loss.

Conclusions

Low educational attainment was independently associated with hearing loss in older adults without dementia in Japan.

Mental Demands at Work and Risk of Dementia

 High mental demands at work was examined as a possible protective factor to reduce the risk of dementia in 1,277 initially dementia-free participants, aged 60 years and older. The cohort was followed for a mean of 13.6 years. During follow-up, 376 participants developed all-cause dementia (Alzheimer’s disease = 199; vascular dementia = 145). The association between mental demands at work and dementia was analyzed with Cox hazard models, adjusted for a range of covariates. The results revealed no significant association between mental demands at work and incidence of dementia. Based on the measures used in this study, it was concluded that high mental demands at work may not reduce the risk of dementia later in life.

Different androgen deprivation therapies might have a differential impact on cognition - An analysis from a population-based study using time-dependent exposure model

BACKGROUND

Androgen deprivation therapy (ADT) remains the mainstay treatment for locally advanced or metastatic prostate cancer (PC). However, potential effects of ADT treatment on neurocognitive dysfunction remain unclear. The present study was conducted to assess the relation between ADT treatment and risk of cognitive decline in Asian men with PC.

METHODS

A population-based cohort of 24,464 men with PC, each newly diagnosed between 2000 and 2008, was selected from the Taiwan National Health Insurance Database. Subjects were further grouped by treatment as non-ADT (n = 4685) or ADT (n = 12,740), members of the latter subjected to bilateral orchiectomy or medical treatment (ie, luteinizing hormone-releasing hormone agonists, antiandrogens, or combination therapy). A multivariable Cox proportional hazard model with ADT as time-dependent covariate was used to generate adjusted hazard ratios (HRs) of subsequent cognitive decline, including dementia, Alzheimer's disease (AD), and Parkinson's disease (PD).

RESULTS

ADT showed a significant association with overall risk of cognitive decline (HR = 1.51, 95 % CI: 1.31-1.74), especially for PD, dementia, and non-Alzheimer dementia (non-AZD). When stratified by various ADT regimens, antiandrogen-only recipients displayed significantly heightened risks of subsequent AD, non-AZD, and PD. However, combined androgen blockade also imposed an increased risk of PD. There was no apparent correlation between duration of ADT exposure and cognitive dysfunction.

CONCLUSIONS

Various ADT therapies may have disparate impacts on cognitive function. Prospective studies exploring pertinent clinical characteristics more fully are needed to confirm these findings.

Decrease in HDL-C is Associated with Age and Household Income in Adults from the Korean National Health and Nutrition Examination Survey 2017: Correlation Analysis of Low HDL-C and Poverty

A low serum high-density lipoproteins-cholesterol (HDL-C) level is a risk factor of cardiovascular disease and dementia. On the other hand, no study has elucidated the correlation between household income and the HDL-C level in the adult population. In the present study, 5535 subjects (20-80 year-old individuals) were selected from the Korean national health and nutrition examination survey 2017 (KNHANES VII-2, n = 2469 men, n = 3066 women). They were classified into five levels of household income grades ranging from one (the lowest) to five (the highest). They were also classified according to the HDL-C level: category 1 (<40 mg/dL, n = 943), category 2 (40-49 mg/dL, n = 1764), category 3 (50-59 mg/dL, n = 1572), category 4 (60-69 mg/dL, n = 820), and category 5 (≥70 mg/dL, n = 436). Generally, in both genders, a higher HDL-C level is associated with a larger percentage of income grades 4 and 5. Moreover, the lowest HDL-C group showed the largest percentage of income grade 1. In both groups, a significant increase in the average income grade was associated with a concomitant increase in the HDL-C level (men, p = 0.03, women, p < 0.001). In the low HDL-C category, a lower income grade is associated directly with a lower HDL-C level, which suggests that poverty is associated directly with a low HDL-C. Women showed a 3.3-fold higher incidence of dementia than men did at later-life. The sharp decrease in HDL-C in the female group older than 50 was accompanied by a dramatic increase in the incidence of dementia. However, the male group showed a relatively mild decrease in the HDL-C level after mid-life and weak elevation in the incidence of dementia. In conclusion, in both genders, the lower income group showed a larger prevalence of low-HDL-C levels. The decrease in HDL-C after middle age was strongly associated with the considerable increase in dementia in later-life.

Use of varenicline and nicotine replacement therapy in people with and without general practitioner-recorded dementia: retrospective cohort study of routine electronic medical records

OBJECTIVES

Our primary objective was to estimate smoking prevalence and prescribing rates of varenicline and nicotine replacement therapy (NRT) in people with and without general practitioner (GP)-recorded dementia. Our secondary objective was to assess and compare quit rates of smokers with versus without GP-recorded dementia who were prescribed varenicline or NRT for smoking cessation.

DESIGN

A retrospective cohort study based on the analysis of electronic medical records within the Clinical Practice Research Datalink (2007-2015).

SETTING

683 general practices in England.

PARTICIPANTS

People with and without GP-recorded dementia, aged 18 years and have a code indicating that they are a current smoker.

INTERVENTION

Index prescription of varenicline or NRT (from 1 September 2006).

OUTCOME MEASURES

The primary outcomes were smoking prevalence and prescribing rates of varenicline and NRT (2007-2015). The secondary outcome was smoking cessation at 2 years.

RESULTS

Age and sex-standardised prevalence of smoking was slightly higher in people with GP-recorded dementia than in those without. There were 235 314 people aged 18 years and above prescribed NRT or varenicline. Among smokers with GP-recorded dementia (N=447), 409 were prescribed NRT and 38 varenicline. Smokers with GP-recorded dementia were 74% less likely (95% CI 64% to 82%) to be prescribed varenicline than NRT, compared with smokers without GP-recorded dementia. Compared with people without GP-recorded dementia, people with GP-recorded dementia had consistently lower prescribing rates of varenicline from 2007 to 2015. Two years after prescription, there was no clear evidence for a difference in the likelihood of smoking cessation after prescription of these medications between individuals with and without dementia (OR 1.0, 95% CI 0.8 to 1.2).

CONCLUSIONS

Between 2007 and 2015, people with GP-recorded dementia were less likely to be prescribed varenicline than those without dementia. Quit rates following prescription of either NRT or varenicline were similar in those with and without dementia.

Associations Among Health Insurance Type, Cardiovascular Risk Factors, and the Risk of Dementia: A Prospective Cohort Study in Korea

Due to an aging population, dementia incidence has rapidly increased in South Korea, heaping psychological and economic burdens upon families and the society. This study was aimed at investigating the associations of health insurance type and cardiovascular risk factors with the risk of dementia. The study was performed using data from 15,043 participants aged 60 years and above, enrolled in the Seoul Dementia Management Project in 2008 and followed up until 2012. Factors such as demographic data, health insurance type, lifestyle factors, and cardiovascular risk factors were subjected to Cox proportional hazard regression analysis to identify their associations with dementia incidence. During the follow-up, 495 participants (3.3%) developed dementia. Medical Aid beneficiaries were associated with an increase in the risk of dementia (hazard ratio [HR] 1.77, 95% confidence interval [CI] 1.421–2.215). Upon analyzing a composite cardiovascular risk score derived from all five cardiovascular risk factors, the risk for dementia incidence in participants increased from 1.56 for the presence of three risk factors to 2.55 for that of four risk factors (HR 2.55, 95% CI 1.174–5.546), compared with those who had no risk factors. The Medical Aid beneficiaries of health insurance type and the presence of multiple cardiovascular risk factors were found to be associated with a higher risk of dementia incidence.

Socioeconomic status and remaining teeth in Japan: results from the Toyama dementia survey

Background

The prevalence of periodontal disease is increasing among elderly individuals in Japan. Reports on the risk factors for tooth loss have included socioeconomic status (SES); however, few studies have addressed the association between remaining teeth and SES by examining whether education and occupation have a synergistic effect on tooth loss. Accordingly, the present study evaluated the association of remaining teeth with the socioeconomic factors of educational and occupational histories in Japanese elderly individuals.

Methods

This retrospective case-control study used data from the Toyama Dementia Survey, Japan. Toyama Prefecture residents aged ≥65 years were randomly selected for the study (sampling rate, 0.5%), and 1303 residents agreed to participate (response rate, 84.8%). Structured interviews with participants and family members (or proxies, if necessary) were conducted. Participants’ lifestyle factors (e.g., smoking and alcohol consumption), medical history, and SES (educational and occupational history) as well as the presence or absence of remaining teeth were assessed. The association between SES and remaining teeth was examined using a logistic regression analysis.

Results

Overall, 275 cases with no remaining teeth and 898 controls with remaining teeth were identified. The odds ratio (OR) for complete tooth loss was higher among less educated participants (≤6 years) than among highly educated participants [age- and sex-adjusted OR, 3.29; 95% confidence interval (CI), 1.90–5.71]; furthermore, it was higher among participants with a blue-collar occupational history than among those with a white-collar occupational history (age- and sex-adjusted OR, 2.16; 95% CI, 1.52–3.06). After adjusting for employment history or educational attainment, the ORs for tooth loss were 2.79–3.07 among less educated participants and 1.89–1.93 among participants with a blue-collar occupational history. A current or former smoking habit and medical history of diabetes and osteoporosis increased the risk of tooth loss. The interaction term of a low level of education and a history of blue-collar occupation with tooth loss was not significant.

Conclusions

In Japan, a low SES is a risk factor for tooth loss. A low level of education is a more important predictor of tooth loss than a blue-collar occupation.

Modifiable Risk Factors Explain Socioeconomic Inequalities in Dementia Risk: Evidence from a Population-Based Prospective Cohort Study

BACKGROUND

Differences in dementia risk across the gradient of socioeconomic status (SES) exist, but their determinants are not well understood.

OBJECTIVE

This study investigates whether health conditions and lifestyle-related risk factors explain the SES inequalities in dementia risk.

METHODS

6,346 participants from the English Longitudinal Study of Ageing were followed up from 2008/2009 until 2014/2015. We used Cox regression adjusted for age, gender, wealth/education, and clustering at the household level to examine the association between SES markers (wealth, education) and time to dementia in a structural equation model including potential mediation or effect modification by a weighted compound score of twelve modifiable risk and protective factors for dementia ('LIfestyle for BRAin health' (LIBRA) score).

RESULTS

During a median follow-up of 6 years, 192 individuals (3.0%) developed dementia. LIBRA scores decreased with increasing wealth and higher educational level. A one-point increase in the LIBRA score was associated with a 13% increase in dementia risk (hazard ratio (HR) = 1.13, 95% confidence interval 1.07-1.19). Higher wealth was associated with a decreased dementia risk (HR = 0.58, 0.39-0.85). Mediation analysis showed that 52% of the risk difference between the highest and lowest wealth tertile was mediated by differences in LIBRA (indirect effect: HR = 0.75, 0.66-0.85). Education was not directly associated with dementia (HR = 1.05, 0.69-1.59), but was a distal risk factor for dementia by explaining differences in wealth and LIBRA scores (indirect effect high education: HR = 0.92, 0.88-0.95).

CONCLUSION

Socioeconomic differences in dementia risk can be partly explained by differences in modifiable health conditions and lifestyle factors.