Risk factors for dementia in Brazil: Differences by region and race

Social and health disparities associated with healthy brain ageing in Brazil and in other Latin American countries

BACKGROUND

Latin American countries present major health-related inequities due to historical, cultural, and social aspects. Recent evidence highlights that factors related to social and health disparities outweigh classic demographic factors in determining healthy brain aging in these populations. However, these analyses have not been conducted with the Brazilian population, the largest and most ethnically diverse population in Latin America.

METHODS

Here, we evaluated demographic, social, and health factors for healthy brain ageing using a machine learning model in a Brazilian population-based cohort (n=9412) and in additional cohorts from other Latin American countries, including Colombia (n=23 694), Chile (n=1301), Ecuador (n=5235), and Uruguay (n=1450).

FINDINGS

In the Brazilian population and other Latin American countries, social and health disparities were more influential than demographic factors for cognition and functional ability. Uniquely in Brazil, education emerged as the primary risk factor impacting cognitive outcomes, diverging from other Latin American countries where mental health symptoms played more prominent roles. In terms of functional ability, Brazil displayed a distinct pattern, with mental health symptoms identified as the primary contributing factor.

INTERPRETATION

Our findings indicate that Brazil converges with other Latin American countries to show that heterogeneous factors impacted more than demographic factors, but also showed a unique set of health factors when compared with other Latin American countries. Therefore, our study emphasises that social and health disparity factors are relevant predictors of healthy brain ageing in Latin America, but population-specific analyses are necessary to identify the specific risk profiles of each country.

FUNDING

None.

TRANSLATIONS

For the Portuguese and Spanish translations of the abstract see Supplementary Materials section.

Preventing dementia in Italy: Estimations of modifiable risk factors and public health implications

BACKGROUND

Dementia is a major global public health challenge, with over 50 million cases in 2020, projected to reach 152 million by 2050. Effective prevention strategies are needed to reduce the impact of modifiable risk factors associated with dementia, particularly in countries with ageing populations like Italy. The Population Attributable Fraction (PAF) and Potential Impact Fraction (PIF) are key metrics for understanding and reducing dementia cases through targeted interventions.

OBJECTIVES

This study aimed to revise and expand PAF estimates for dementia in Italy, integrate them with PIF calculations, and assess the alignment of regional health policies with these risk factors. Additionally, the study explored regional variations in PAFs and evaluated the potential for reducing dementia incidence through feasible public health interventions.

DESIGN

A cross-sectional analysis was conducted using data from two national public health surveillance systems, PASSI and PASSI d'Argento (PdA), to estimate PAFs and PIFs for dementia at both national and regional levels. The study used data collected between 2017 and 2019.

SETTING

Data were drawn from 19 Italian regions and two autonomous provinces, providing national and subnational estimates of modifiable risk factors for dementia.

PARTICIPANTS

The study population included a nationally representative sample of 86,494 individuals aged 18-64 (PASSI) and 48,516 individuals aged 65 and older (PdA).

MEASUREMENTS

PAFs were calculated for 11 of the 12 modifiable risk factors identified by the Lancet Commission in 2021, with data from the PASSI and PdA systems. PIFs were calculated to estimate the potential reduction in dementia cases under different intervention scenarios. Regional variations in PAFs were assessed and aligned with health policies outlined in the Regional Prevention Plans.

RESULTS

The national combined PAF for 11 modifiable risk factors was 39.6 % (95 % CI: 20.8-55.9). Midlife hypertension and physical inactivity were the most significant contributors, accounting for 12.3 % of the total PAF. Cardiovascular risk factors collectively explained over 50 % of preventable dementia cases. Regional PAFs ranged from 31.7 % to 47.5 %, with a clear north-south gradient; southern regions exhibited higher PAFs due to cardiovascular factors. Despite broad consistency between national and regional PAFs, significant variability was found in how regions addressed risk factors, particularly air pollution. At the national level, a 10 % reduction in risk factors would prevent 54,495 dementia cases, with subnational PIFs ranging from 3.7 % to 6.0 %.

CONCLUSIONS

This study highlights the substantial potential for dementia prevention in Italy through targeted public health interventions. However, significant regional disparities in PAFs and the alignment of health policies underscore the need for a more nuanced, regionally tailored approach. Future strategies should integrate both PAF and PIF to maximize the impact of interventions, particularly in addressing cardiovascular risk factors. These findings can guide the development of evidence-based policies to reduce dementia incidence across Italy.

Association of Alcohol Consumption with Cognition and Functionality in Older Adults Aged 75+ Years: The Pietà Study

The relationship between alcohol consumption and cognition is still controversial. This is a cross-sectional population-based study conducted in Caeté (MG), Brazil, where 602 individuals aged 75+ years, 63.6% female, and with a mean education of 2.68 years, were submitted to thorough clinical assessments and categorized according to the number of alcoholic beverages consumed weekly. The prevalence rates of previous and current alcohol consumption were 34.6% and 12.3%, respectively. No association emerged between cognitive diagnoses and current/previous alcohol consumption categories. Considering current alcohol intake as a dichotomous variable, the absence of alcohol consumption was associated with dementia (OR = 2.34; 95%CI: 1.39-3.90) and worse functionality (p = 0.001). Previous consumption of cachaça (sugar cane liquor) increased the risk of dementia by 2.52 (95%CI: 1.25-5.04). The association between the consumption of cachaça and dementia diagnosis has not been described before.

Prevalence and population attributable fractions of potentially modifiable risk factors for dementia in Canada: A cross-sectional analysis of the Canadian Longitudinal Study on Aging

OBJECTIVES

We investigated the prevalence and population attributable fraction (PAF) of 12 potentially modifiable risk factors for dementia in middle-aged and older Canadians.

METHODS

We conducted a cross-sectional study of 30,097 adults aged 45 to 85 with baseline data from the Canadian Longitudinal Study on Aging (2011‒2015). Risk factors and associated relative risks were taken from a highly cited systematic review. We calculated the prevalence of each risk factor using sampling weights. Individual PAFs were calculated both crudely and weighted for communality, and combined PAFs were calculated using both multiplicative and additive assumptions. Analyses were stratified by household income and repeated at CLSA's first follow-up (2015‒2018).

RESULTS

The most prevalent risk factors were physical inactivity (63.8%; 95% CI, 62.8-64.9), hypertension (32.8%; 31.7-33.8), and obesity (30.8%; 29.7-31.8). The highest crude PAFs were physical inactivity (19.9%), traumatic brain injury (16.7%), and hypertension (16.6%). The highest weighted PAFs were physical inactivity (11.6%), depression (7.7%), and hypertension (6.0%). We estimated that the 12 risk factors combined accounted for 43.4% (37.3‒49.0) of dementia cases assuming weighted multiplicative interactions and 60.9% (55.7‒65.5) assuming additive interactions. There was a clear gradient of increasing prevalence and PAF with decreasing income for 9 of the 12 risk factors.

CONCLUSION

The findings of this study can inform individual- and population-level dementia prevention strategies in Canada. Differences in the impact of individual risk factors between this study and other international and regional studies highlight the importance of tailoring national dementia strategies to the local distribution of risk factors.

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.

Female Reproductive Period Length, Parity and Hormonal Replacement Therapy and Dementia: The Elsi-Brazil Study

INTRODUCTION

Alzheimer's disease and other dementia have a higher incidence among women and that risk factors specific to the female sex could be involved. Few studies looked into female reproductive factors and their association with dementia in low-and middle-income countries.

MATERIALS AND METHODS

We analyzed the baseline data from the Brazilian Longitudinal Study of Aging (ELSI-Brazil) and included data from 2594 women aged 60 years and older. We used an algorithm approach to determine dementia status and performed logistic regressions using as predictors the self-reported total length of the reproductive period, total parity and use of hormonal replacement therapy. We also analyzed the effects of hormonal replacement therapy use for different age groups and the effects of number of living children.

RESULTS

Reproductive period length, hormonal replacement therapy use and parity as a continuous measure were not significantly associated with dementia status. When compared with 0 births, the group with 5-8 had more dementia while the other groups displayed no differences. For the number of living children, but a higher occurrence of dementia was found among women with more children.

CONCLUSIONS

We did not find any association between continuous parity, reproductive period length or hormonal replacement therapy use and dementia. Social factors of motherhood appear to play an important role, and group specific effects of parity and hormonal replacement therapy require further study.

The landscape of dementia research in Brazil from 2010 to 2021: a Scopus-based bibliometric study

BACKGROUND

 Several studies have sought to investigate the trajectory of scholarly publications on dementia. Yet, there has been limited attention to contributions from Latin America.

OBJECTIVE

 To provide a comprehensive overview of the literature output on dementia in Brazil.

METHODS

 We conducted a Scopus-based literature search (2010-2021) for publications by authors affiliated with Brazil.

RESULTS

 Out of 5,534 reports, 2,528 met the inclusion criteria. The annual growth rate of publications on dementia (9.9%, SD = 15.5) closely paralleled that of general health-related literature (6.7%, SD = 4.9). Most publications were categorized into the areas of diagnosis (33.4%) and disease mechanisms, origins, and models (32.7%). Epidemiological studies (4%), clinical trials (1%), and economic analyses (0.3%) are scarce. Based on the first affiliation of Brazil-affiliated authors, 89.3% of dementia output stemmed from Southeast (68.4%) and South (20.9%) of Brazil. Nonetheless, the state of São Paulo alone accounted for 41.1%, contributing to 60.1% of the Southeast. First and second authorships were predominantly held by female researchers, whereas male researchers occupied most of the second-to-last and last authorships. Overall, 1,812 (71.7%) were published in 346 foreign journals and 716 (28.3%) in 43 Brazilian journals. Notably, nearly half of the reports published in Brazil are concentrated in two journals: Dementia e Neuropsychologia (31.4%) and Arquivos de Neuro-Psiquiatria (15.2%).

CONCLUSION

 There is a pressing need for more studies in dementia epidemiology and economic cost, in addition to more research across all Brazilian regions.

Population attributable fractions for risk factors for dementia in seven Latin American countries: an analysis using cross-sectional survey data

BACKGROUND

Approximately 40% of dementia cases worldwide are attributable to 12 potentially modifiable risk factors. However, the proportion attributable to these risks in Latin America remains unknown. We aimed to determine the population attributable fraction (PAF) of 12 modifiable risk factors for dementia in seven countries in Latin America.

METHODS

We used data from seven cross-sectional, nationally representative surveys with measurements of 12 modifiable risk factors for dementia (less education, hearing loss, hypertension, obesity, smoking, depression, social isolation, physical inactivity, diabetes, excessive alcohol intake, air pollution, and traumatic brain injury) done in Argentina, Brazil, Bolivia, Chile, Honduras, Mexico, and Peru. Data were collected between 2015 and 2021. Sample sizes ranged from 5995 to 107 907 participants (aged ≥18 years). We calculated risk factor prevalence and communalities in each country and used relative risks from previous meta-analyses to derive weighted PAFs. Pooled PAFs for Latin America were obtained using random effect meta-analyses.

FINDINGS

The overall proportion of dementia cases attributed to 12 modifiable risk factors varied across Latin American countries: weighted PAF 61·8% (95% CI 37·9-79·5) in Chile, 59·6% (35·8-77·3) in Argentina, 55·8% (35·7-71·5) in Mexico, 55·5% (35·9-70·4) in Bolivia, 53·6% (33·0-69·3) in Honduras, 48·2% (28·1-63·9) in Brazil, and 44·9% (25·8-61·2) in Peru. The overall PAF for dementia was 54·0% (48·8-59·6) for Latin America. The highest weighted PAFs in Latin American countries overall were for obesity (7%), physical inactivity (6%), and depression (5%).

INTERPRETATION

The estimated PAFs for Latin American countries were higher than previous global estimates. Obesity, physical inactivity, and depression were the main risk factors for dementia across seven Latin American countries. These findings have implications for public health and individually targeted dementia prevention strategies in Latin America. Although these results provide new information about Latin American countries, demographics and representativeness variations across surveys should be considered when interpreting these findings.

FUNDING

None.

Five Digit Test in neuropsychological assessment of working memory in aged individuals:normative data

Five Digit Test (FDT) is an executive function assessment tool designed to be used across the lifespan, from children to the aged.

Objective

To provide validity evidence for FDT in the neuropsychological assessment of working memory in the aged.

Methods

A total of 100 subjects, aged between 56 and 86 years, representing both genders with varying levels of education, underwent a comprehensive clinical history and neuropsychological evaluation using FDT. The mean age of participants was 71.04 years, with 67.3% having intermediate education. Participants were categorized into two groups: Control Group and Cognitive Decline Group. To establish validity evidence, FDT scores (both time and errors) were correlated with the WAIS-III Digits scale. Spearman's correlation coefficient and ROC curve methodology were employed to determine psychometric properties.

Results

A significant and moderate negative correlation was evident between FDT Shifting (number of errors) and Digits score (rho=-0.51; p<0.0001), Direct Order (rho=-0.39; p<0.0001), and Indirect Order (rho=-0.46; p<0.0001). The area under the curve was higher for FDT Shifting (errors) (AUC=0.935) for a cutoff point greater than or equal to 5 points, compared to Digits (AUC=0.748).

Conclusion

The assessment of the number of errors in FDT Shifting appears to be a statistically significant tool for evaluating working memory impairment in the aged.

Association of Moderate and Vigorous Physical Activity With Cognitive Performance: Evidence From Brazil

OBJECTIVE

It is estimated that 2% of dementia cases worldwide could be prevented with increases in physical activity. However, there is little evidence of the association between vigorous physical activity (VPA) and cognitive performance. This study aimed to investigate the association of moderate physical activity (MPA) and VPA with cognitive performance in older adults from the Brazilian Longitudinal Study of Aging (ELSI-Brasil).

PATIENTS AND METHODS

Data from 7954 participants were analyzed. Mean age was 61.8 ± 9.2 years, 61.8% were women, and 44.3% were mixed races. Cognitive performance evaluated the memory, temporal orientation, and verbal fluency domains. A global composite z-score was derived from the tests. Physical activity was assessed by self-report. We used linear regression models to verify the association of MPA and VPA with cognitive performance.

RESULTS

Compared with participants who did not meet the guidelines for MPA (<150 min/wk), those who met the guidelines (150 to 299 min/wk) and those who performed more than 2x the recommended amount of MPA (300 min or more/wk) had better global cognitive performance (β = 0.163, 95% CI = 0.086, 0.241; P < 0.001; β = 0.180, 95% CI = 0.107, 0.253, P < 0.001, respectively). We found no association between VPA and cognitive performance.

CONCLUSION

There was no additional benefit of VPA for cognitive performance.

Advancements in dementia research, diagnostics, and care in Latin America: Highlights from the 2023 Alzheimer's Association International conference satellite symposium in Mexico City

INTRODUCTION

While Latin America (LatAm) is facing an increasing burden of dementia due to the rapid aging of the population, it remains underrepresented in dementia research, diagnostics, and care.

METHODS

In 2023, the Alzheimer's Association hosted its eighth satellite symposium in Mexico, highlighting emerging dementia research, priorities, and challenges within LatAm.

RESULTS

Significant initiatives in the region, including intracountry support, showcased their efforts in fostering national and international collaborations; genetic studies unveiled the unique genetic admixture in LatAm; researchers conducting emerging clinical trials discussed ongoing culturally specific interventions; and the urgent need to harmonize practices and studies, improve diagnosis and care, and use affordable biomarkers in the region was highlighted.

DISCUSSION

The myriad of topics discussed at the 2023 AAIC satellite symposium highlighted the growing research efforts in LatAm, providing valuable insights into dementia biology, genetics, epidemiology, treatment, and care.

Episodic memory improvement in illiterate adults attending late-life education irrespective of low socioeconomic status: insights from the PROAME study

The majority of people with dementia live in low or middle-income countries (LMICs) where resources that play a crucial role in brain health, such as quality education, are still not widely available. In Brazil, illiteracy remains a prevalent issue, especially in communities with lower socioeconomic status (SES). The PROAME study set out to explore basic education in illiterate adults as a means to improve cognitive reserve.

Objective

This manuscript aims to explore the relationship between SES and learning, as well as cognitive outcomes, in an older illiterate population.

Methods

This six-month clinical trial (NCT04473235) involved 108 participants, of which 77 concluded all assessments, enrolled in late-life basic education. SES assessments included Quality of Urban Living Index, Municipal Human Development Index and Household SES calculated for each participant. Cognitive assessments encompassed the Free and Cued Selective Reminding Test (FCSRT), a word list to assess reading, and the Beta III matrix.

Results

The sample consisted primarily of women, with a mean age of 58.5. Participants improved their reading (p=0.01) and their FCSRT (p=0.003). Regarding episodic memory, women outperformed men (p=0.007) and younger participants improved more than their older counterparts (p=0.001). There was no association observed between SES and cognitive outcomes.

Conclusion

Irrespective of SES, participants demonstrated positive outcomes after attending basic education. These findings highlight that late life education could be an important non-pharmacologic preventative measure, especially in LMICs.

Alzheimer's disease: part 2 - the present

Based on my work as a clinical neurologist with more than 50 years of experience in caring for patients with Alzheimer's disease (AD), I focus, in this review article, on the disease's two fundamental aspects for the doctor: diagnosis and treatment. The 1984 diagnostic criteria had been stable for more than a quarter of a century when it was replaced in 2011. Since then, there have been many discoveries, especially of biomarkers that have a heavy impact on the diagnosis of AD. Recently, AD biomarkers have become available in plasma, which certainly will cause a major change in the diagnosis of biological AD, a term that still needs care and information to society before being used in clinical practice. Three monoclonal antibodies against β-amyloid peptide have also been recently approved, and two of these have shown a small but statistically significant effect on clinical outcome. These monoclonal antibodies have had a greater effect on the reduction of amyloid plaques in the brain assessed by positron emission tomography (PET), and on the concentration of biomarkers in the cerebrospinal fluid (β-amyloid peptide with 42 amino acids and hyperphosphorylated tau protein) than in the neuropsychological and functional assessments. Even this small clinical effect will be encouraging for the development of new research, particularly helped by the greater ease of diagnosis and monitoring of the evolution of AD pathophysiology with plasma biomarkers. Recently, new diagnostic criteria for AD were presented by the Alzheimer's Association, causing controversy about their use in clinical practice.

Population attributable fractions of modifiable risk factors for dementia: a systematic review and meta-analysis

BACKGROUND

More than 57 million people have dementia worldwide. Evidence indicates a change in dementia prevalence and incidence in high-income countries, which is likely to be due to improved life-course population health. Identifying key modifiable risk factors for dementia is essential for informing risk reduction and prevention strategies. We therefore aimed to estimate the population attributable fraction (PAF) for dementia associated with modifiable risk factors.

METHODS

In this systematic review and meta-analysis, we searched Embase, MEDLINE, and PsycINFO, via Ovid, from database inception up to June 29, 2023, for population-derived or community-based studies and reviews reporting a PAF value for one or more modifiable risk factor for later-life dementia (prevalent or incident dementia in people aged ≥60 years), with no restrictions on dementia subtype, the sex or baseline age of participants, or the period of study. Articles were independently screened for inclusion by four authors, with disagreements resolved through consensus. Data including unweighted and weighted PAF values (weighted to account for communality or overlap in risk) were independently extracted into a predefined template by two authors and checked by two other authors. When five or more unique studies investigated a given risk factor or combination of the same factors, random-effects meta-analyses were used to calculate a pooled PAF percentage estimate for the factor or combination of factors. The review protocol was registered on PROSPERO, CRD42022323429.

FINDINGS

4024 articles were identified, and 74 were included in our narrative synthesis. Overall, PAFs were reported for 61 modifiable risk factors, with sufficient data available for meta-analysis of 12 factors (n=48 studies). In meta-analyses, the highest pooled unweighted PAF values were estimated for low education (17·2% [95% CI 14·4-20·0], p<0·0001), hypertension (15·8% [14·7-17·1], p<0·0001), hearing loss (15·6% [10·3-20·9], p<0·0001), physical inactivity (15·2% [12·8-17·7], p<0·0001), and obesity (9·4% [7·3-11·7], p<0·0001). According to weighted PAF values, low education (9·3% [6·9-11·7], p<0·0001), physical inactivity (7·3% [3·9-11·2], p=0·0021), hearing loss (7·2% [5·2-9·7], p<0·0001), hypertension (7·1% [5·4-8·8], p<0·0001), and obesity (5·3% [3·2-7·4], p=0·0001) had the highest pooled estimates. When low education, midlife hypertension, midlife obesity, smoking, physical inactivity, depression, and diabetes were combined (Barnes and Yaffe seven-factor model; n=9 studies), the pooled unweighted and weighted PAF values were 55·0% (46·5-63·5; p<0·0001) and 32·0% (26·6-37·5; p<0·0001), respectively. The pooled PAF values for most individual risk factors were higher in low-income and middle-income countries (LMICs) versus high-income countries.

INTERPRETATION

Governments need to invest in a life-course approach to dementia prevention, including policies that enable quality education, health-promoting environments, and improved health. This investment is particularly important in LMICs, where the potential for prevention is high, but resources, infrastructure, budgets, and research focused on ageing and dementia are limited.

FUNDING

UK Research and Innovation (Medical Research Council).

Poor sleep quality is an important modifiable risk factor for dementia: Population attributable fraction of poor sleep in a Brazilian population-based study

OBJECTIVES

The populational impact of poor sleep quality and the risk of dementia is unclear. We analyzed the Population Attributable Fraction (PAF) of poor sleep quality for dementia, and its association with other two sleep parameters through self-reported and single questions collected in a large-scale Brazilian cohort (ELSI-Brazil).

METHODS

A subset of the ELSI-Brazil with complete responses to sleep quality was retrieved for this study. This is a large representative sample of the Brazilian elderly population with an extensive assessment of sociodemographic and health risk variables. Prevalence of poor sleep quality was estimated according to the complex sample design, and its PAF was measured using a meta-analytic relative risk. A total of 6024 (56.3% women, mean 62.8 ± 9.5 years of age) individuals had complete responses.

RESULTS

The prevalence of poor sleep quality was 24.9% (95%CI 23%-26%), and the PAF of poor sleep quality including other 10 modifiable risk factors of dementia was 52.5% in Brazil. Secondary analyses identified that sleep quality, restorative sleep and sleep drug usage varied considerably according to age ranges, race, and gender.

CONCLUSIONS

Poor sleep quality is an important populational modifiable risk factor for dementia in Brazil. Targeted interventions may provide an important impact in preventing dementia in low- and middle-income countries.

The 2022 symposium on dementia and brain aging in low- and middle-income countries: Highlights on research, diagnosis, care, and impact

Two of every three persons living with dementia reside in low- and middle-income countries (LMICs). The projected increase in global dementia rates is expected to affect LMICs disproportionately. However, the majority of global dementia care costs occur in high-income countries (HICs), with dementia research predominantly focusing on HICs. This imbalance necessitates LMIC-focused research to ensure that characterization of dementia accurately reflects the involvement and specificities of diverse populations. Development of effective preventive, diagnostic, and therapeutic approaches for dementia in LMICs requires targeted, personalized, and harmonized efforts. Our article represents timely discussions at the 2022 Symposium on Dementia and Brain Aging in LMICs that identified the foremost opportunities to advance dementia research, differential diagnosis, use of neuropsychometric tools, awareness, and treatment options. We highlight key topics discussed at the meeting and provide future recommendations to foster a more equitable landscape for dementia prevention, diagnosis, care, policy, and management in LMICs. HIGHLIGHTS: Two-thirds of persons with dementia live in LMICs, yet research and costs are skewed toward HICs. LMICs expect dementia prevalence to more than double, accompanied by socioeconomic disparities. The 2022 Symposium on Dementia in LMICs addressed advances in research, diagnosis, prevention, and policy. The Nairobi Declaration urges global action to enhance dementia outcomes in LMICs.

Memory complaint in a middle-income country: a four-year longitudinal study in a cohort with low-education

BACKGROUND

 Memory complaints are frequent in older adults and are associated with higher risk of cognitive decline.

OBJECTIVE

 To investigate the functional outcome of individuals with memory complaints followed up at primary care centers.

METHODS

 Data were collected between 2016 e 2020 in primary health care centers in Brazil. Patients underwent the Brief Cognitive Screening Battery, and the Functional Activities Questionnaire.

RESULTS

 The initial sample (2016) comprised 91 individuals classified into those with subjective cognitive decline (SCD, n = 15), mild cognitive impairment (MCI, n = 45), or dementia (n = 31). During follow-up, 8 individuals (8.8% of the initial sample) died and 26 (28.5% of the initial sample) were not found. Fifty-seven participants underwent clinical reassessment. Of 15 individuals with SCD, 7 were not found (46.7%), 4 (26.7%) progressed to MCI, and 4 (26.7%) remained stable. Of 45 individuals with MCI, 11 were not found (24.4%), 2 (4.4%) died, 6 (13.4%) progressed to dementia, 12 (26.7%) regressed to SCD, and 14 (31.1%) remained stable. Of 31 individuals with dementia, 8 were not found (25.8%), 6 (19.4%) died, 2 (6.5%) regressed to SCD, 7 (22.6%) regressed to MCI, and 8 remained stable (25.8%). Clinical improvement was due to the treatment of reversible causes, such as B12 hypovitaminosis and mood disorders. Older age, lower Mini-Mental State Examination, and higher scores of memory complaint, but not the use of benzodiazepines and of proton pump inhibitors, were predictors of functional status.

CONCLUSION

 Despite their limits (short sample size, missing data), these results support the idea that adequate screening, follow-up, and treatment of reversible causes of dementia in primary care are essential.

Plasma ADAM10 Levels and Their Association with Alzheimer's Disease Diagnosis in Older Adults with Fewer Years of Formal Education

INTRODUCTION

Low educational attainment is a potential risk factor for Alzheimer's disease (AD) development. Alpha-secretase ADAM10 plays a central role in AD pathology, attenuating the formation of beta-amyloid peptides and, therefore, their aggregation into senile plaques. This study seeks to investigate ADAM10 as a blood-based biomarker in mild cognitive impairment (MCI) and AD in a diverse group of community-dwelling older adults, focusing on those with limited educational attainment.

METHODS

Participants were recruited from public health services. Cognition was evaluated using Mini-Mental State Examination (MMSE) and Addenbrooke's Cognitive Examination - Revised (ACE-R) batteries. Blood samples were collected to analyze plasma ADAM10 levels. A logistic regression was conducted to verify the influence of plasma ADAM10 on the AD diagnosis.

RESULTS

Significant differences in age, years of education, prescribed medications, and cognitive test scores were found between the MCI and AD groups. Regarding cognitive performance, both ACE-R and MMSE scores displayed significant differences between groups, with post hoc analyses highlighting these distinctions, particularly between AD and cognitively unimpaired individuals. Elevated plasma ADAM10 levels were associated with a 4.5-fold increase in the likelihood of a diagnosis of MCI and a 5.9-fold increase in the likelihood of a diagnosis of AD. These findings suggest ADAM10 levels in plasma as a valuable biomarker for assessing cognitive status in older individuals with low education attainment.

CONCLUSION

This study underscores the potential utility of plasma ADAM10 levels as a blood-based biomarker for cognitive status, especially in individuals with low educational backgrounds, shedding light on their relevance in AD development and diagnosis.

Intelligent decision support systems for dementia care: A scoping review

In the context of dementia care, Artificial Intelligence (AI) powered clinical decision support systems have the potential to enhance diagnosis and management. However, the scope and challenges of applying these technologies remain unclear. This scoping review aims to investigate the current state of AI applications in the development of intelligent decision support systems for dementia care. We conducted a comprehensive scoping review of empirical studies that utilised AI-powered clinical decision support systems in dementia care. The results indicate that AI applications in dementia care primarily focus on diagnosis, with limited attention to other aspects outlined in the World Health Organization (WHO) Global Action Plan on the Public Health Response to Dementia 2017-2025 (GAPD). A trifecta of challenges, encompassing data availability, cost considerations, and AI algorithm performance, emerges as noteworthy barriers in adoption of AI applications in dementia care. To address these challenges and enhance AI reliability, we propose a novel approach: a digital twin-based patient journey model. Future research should address identified gaps in GAPD action areas, navigate data-related obstacles, and explore the implementation of digital twins. Additionally, it is imperative to emphasize that addressing trust and combating the stigma associated with AI in healthcare should be a central focus of future research directions.

Leisure-Time Physical Activity May Attenuate the Impact of Diabetes on Cognitive Decline in Middle-Aged and Older Adults: Findings From the ELSA-Brasil Study

OBJECTIVE

To assess leisure-time physical activity (LTPA) as a modifier of the diabetes/cognitive decline association in middle-aged and older participants in the Estudo Longitudinal de Saude do Adulto (ELSA-Brasil) study.

RESEARCH DESIGN AND METHODS

ELSA-Brasil is a cohort of 15,105 participants (age 35-74 years) enrolled between 2008 and 2010. We evaluated global cognitive function, summing the scores of six standardized tests evaluating memory and verbal fluency, including the Trail-Making Test, at baseline and follow-up. Incident cognitive impairment was defined as a global cognitive function score at follow-up lower than -1 SD from baseline mean. Participants reporting ≥150 min/week of moderate to vigorous LTPA at baseline were classified as physically active. We assessed the association of LTPA with global cognition change in those with diabetes in the context of our overall sample through multivariable regression models.

RESULTS

Participants' (N = 12,214) mean age at baseline was 51.4 (SD 8.8) years, and 55.5% were women. During a mean follow-up of 8.1 (SD 0.6) years, 9,345 (76.5%) inactive participants and 1,731 (14.1%) participants with diabetes at baseline experienced faster declines in global cognition than those who were active (β = -0.003, -0.004, and -0.002) and those without diabetes (β = -0.004, -0.005, and -0.003), respectively. Diabetes increased the risk of cognitive impairment (hazard ratio [HR] 1.71; 95% Cl 1.22, 2.39) in inactive but not in active adults (HR 1.18; 95% CI 0.73, 1.90). Among participants with diabetes, those who were active showed a delay of 2.73 (95% CI 0.94, 4.51) years in the onset of cognitive impairment.

CONCLUSIONS

In adults living with diabetes, LTPA attenuated the deleterious association between diabetes and cognitive function.

Sex and Socioeconomic Disparities in Dementia Risk: A Population-Attributable Fraction Analysis in Argentina

INTRODUCTION

Twelve modifiable risk factors (RFs) account for 40% of dementia cases worldwide. However, limited data exist on such factors in middle- and low-income countries. We aimed to estimate the population-attributable fractions (PAFs) for the 12 RFs in Argentina, assessing changes over a decade and exploring socioeconomic and sex influences.

METHODS

We conducted cross-sectional analyses of the 12 RFs from Argentinian surveys conducted in 2009, 2015, and 2018, including 96,321 people. We calculated PAFs and stratified estimates based on sex and income.

RESULTS

We estimated an overall PAF of 59.6% (95% CI = 58.9-60.3%). The largest PAFs were hypertension = 9.3% (8.7-9.9%), physical inactivity = 7.4% (6.8-8.2%), and obesity = 7.4% (6.8-7.9%). Men were more impacted by excessive alcohol, while women by isolation and smoking. Lower income linked to higher PAFs in education, hypertension, and obesity.

DISCUSSION

Argentina has a higher PAF for dementia than the world population, with distinct RF distribution. PAF varied by sex and economic status, advocating tailored prevention strategies.

Effects of Hearing Aid Use on Individuals Diagnosed with Hearing Loss and Dementia: A Systematic Review

Background

The assumption that hearing rehabilitation could improve quality of life and reduce dementia risk in people with hearing loss is a subject that needs further studies, especially clinical trials. It is necessary to determine the effects of hearing aid use, as part of hearing rehabilitation, among people diagnosed with dementia.

Objective

To systematically review the literature to evaluate the effects of hearing aid use on cognition and quality of life of people with dementia.

Methods

Protocol for this systematic review was registered (CRD42023387187). The Cochrane Central Register of Controlled Trials, Embase, MEDLINE, Scopus, CINAHL, and Web of Science databases, as well as grey literature, including Google Scholar and ResearchGate, were systematically searched for clinical trials using MeSH terms. The PICOS principle was used to develop the inclusion criteria: population (P): adults and older adults, individuals diagnosed with dementia and hearing loss; intervention (I): rehabilitation with hearing aids; control (C): not using a hearing aid; outcome (O): cognitive and/or quality of life assessment using validated tests; study design (S): clinical trial.

Results

The initial search yielded 576 studies, five of which met the inclusion criteria for qualitative analyses. Two of the included studies were randomized clinical trials, and three were crossover clinical trials, demonstrating the lack of studies on the subject. Four studies included participants with Alzheimer's disease. Quality of life was found to improve with the use of hearing aids, and hearing rehabilitation was not shown to affect cognitive outcomes.

Conclusions

Hearing aid use appears to have a positive impact on quality of life.

Potential for prevention of dementia in Denmark

INTRODUCTION

According to previous estimates, 40% of dementia cases globally may be attributed to 12 potentially modifiable risk factors.

METHODS

We calculated national population attributable fractions (PAFs) for each risk factor and modeled the effects of proportional reductions in risk factor prevalence on dementia prevalence by calculating potential impact fractions (PIFs) for each factor.

RESULTS

The overall adjusted PAF for all risk factors was 35.2%. Physical inactivity, hearing loss, hypertension, and obesity accounted for 64% of the total prevention potential. The overall adjusted PIF was 4.1% at 10% risk factor prevalence reduction and 8.1% at 20% risk factor reduction.

DISCUSSION

Estimates of the potential for the prevention of dementia should be based on country-specific data on risk factor prevalence, as estimates based on global risk factor prevalence have limited relevance from a national perspective. Physical inactivity, hearing loss, hypertension, and obesity could be primary targets for prevention of dementia in Denmark.

HIGHLIGHTS

Overall adjusted PAF for potentially modifiable dementia risk factors was 35%. Physical inactivity, hearing loss, hypertension, and obesity had the largest prevention potential. Estimates of prevention potential should be based on national risk factor prevalence.

Latin American Initiative for Lifestyle Intervention to Prevent Cognitive Decline (LatAm-FINGERS): Study design and harmonization

INTRODUCTION

Latin American Initiative for Lifestyle Intervention to Prevent Cognitive Decline (LatAm-FINGERS) is the first non-pharmacological multicenter randomized clinical trial (RCT) to prevent cognitive impairment in Latin America (LA). Our aim is to present the study design and discuss the strategies used for multicultural harmonization.

METHODS

This 1-year RCT (working on a 1-year extension) investigates the feasibility of a multi-domain lifestyle intervention in LA and the efficacy of the intervention, primarily on cognitive function. An external harmonization process was carried out to follow the FINGER model, and an internal harmonization was performed to ensure this study was feasible and comparable across the 12 participating LA countries.

RESULTS

Currently, 1549 participants have been screened, and 815 randomized. Participants are ethnically diverse (56% are Nestizo) and have high cardiovascular risk (39% have metabolic syndrome).

DISCUSSION

LatAm-FINGERS overcame a significant challenge to combine the region's diversity into a multi-domain risk reduction intervention feasible across LA while preserving the original FINGER design.

Protecting cognitive function in older adults with age-related hearing loss: Insights from The Irish Longitudinal Study on Ageing (TILDA) and the role of hearing aids

BACKGROUND

Age-related hearing loss (ARHL) is prevalent in adults over 70, impairing hearing sensitivity and speech perception. ARHL has been linked to an increased risk of cognitive decline and dementia. However, most affected adults are not receiving adequate treatment, including hearing aids.

OBJECTIVE

This study aimed to evaluate the impact of ARHL on cognitive decline in older adults participating in the Irish Longitudinal Study on Aging (TILDA).

DESIGN

METHODS: Data from four TILDA waves, a 6-year follow-up, was collected and analyzed using zero-inflated Poisson regression. The primary outcome, cognitive function, was assessed using Mini-Mental State Examination (MMSE) total score and error counts.

RESULTS

Our analysis revealed that age, education, use of aids to help with hearing, and history of stroke were significantly associated with error counts at baseline. Additionally, poor hearing was associated with a negative change in MMSE score from wave 4, indicating the potential role of ARHL in cognitive decline. When further adjusted for age, sex, history of stroke, hypertension, any emotional, nervous, or psychiatric problem, polypharmacy, and hearing aids, the zero-inflated Poisson model indicated that poor hearing, use of hearing aids, stroke, hypertension, and polypharmacy all predicted MMSE error counts in follow-up assessments. Moreover, the use of hearing aids was associated with a decreased likelihood of cognitive decline.

CONCLUSION

ARHL was independently associated with cognitive decline, underscoring the importance of addressing hearing loss in older adults. Future research should explore the potential of hearing aids to protect cognitive functioning in older adults.

Potentially modifiable dementia risk factors in all Australians and within population groups: an analysis using cross-sectional survey data

BACKGROUND

Dementia is the second leading cause of disease burden in Australia. We aimed to calculate the population attributable fractions (PAFs) of dementia attributable to 11 of 12 previously identified potentially modifiable health and social risk factors (less education, hearing loss, hypertension, obesity, smoking, depression, social isolation, physical inactivity, diabetes, alcohol excess, air pollution, and traumatic brain injury), for Australians overall and three population groups (First Nations, and those of European and Asian ancestry).

METHODS

We calculated the prevalence of dementia risk factors (excluding traumatic brain injury) and PAFs, adjusted for communality, from the cross-sectional National Aboriginal and Torres Strait Islander Health Survey (2018-19), National Aboriginal and Torres Strait Islander Social Survey (2014-15), National Health Survey (2017-18), and General Social Survey (2014) conducted by the Australian Bureau of Statistics. We conducted sensitivity analyses using proxy estimates for traumatic brain injury (12th known risk factor) for which national data were not available.

FINDINGS

A large proportion (38·2%, 95% CI 37·2-39·2) of dementia in Australia was theoretically attributable to the 11 risk factors; 44·9% (43·1-46·7) for First Nations Australians, 36·4% (34·8-38·1) for European ancestry, and 33·6% (30·1-37·2) for Asian ancestry. Including traumatic brain injury increased the PAF to 40·6% (39·6-41·6) for all Australians. Physical inactivity (8·3%, 7·5-9·2), hearing loss (7·0%, 6·4-7·6), and obesity (6·6%, 6·0-7·3) accounted for approximately half of the total PAF estimates across Australia, and for all three population groups.

INTERPRETATION

Our PAF estimates indicate a substantial proportion of dementia in Australia is potentially preventable, which is broadly consistent with global trends and results from other countries. The highest potential for dementia prevention was among First Nations Australians, reflecting the enduring effect of upstream social, political, environmental, and economic disadvantage, leading to greater life-course exposure to dementia risk factors. Although there were common dementia risk factors across different population groups, prevention strategies should be informed by community consultation and be culturally and linguistically appropriate.

FUNDING

Australian National Health and Medical Research Council and University College London Hospitals' National Institute for Health Research (NIHR) Biomedical Research Centre, and North Thames NIHR Applied Research Collaboration.

Sex differences in dementia risk and risk factors: Individual-participant data analysis using 21 cohorts across six continents from the COSMIC consortium

INTRODUCTION

Sex differences in dementia risk, and risk factor (RF) associations with dementia, remain uncertain across diverse ethno-regional groups.

METHODS

A total of 29,850 participants (58% women) from 21 cohorts across six continents were included in an individual participant data meta-analysis. Sex-specific hazard ratios (HRs), and women-to-men ratio of hazard ratios (RHRs) for associations between RFs and all-cause dementia were derived from mixed-effect Cox models.

RESULTS

Incident dementia occurred in 2089 (66% women) participants over 4.6 years (median). Women had higher dementia risk (HR, 1.12 [1.02, 1.23]) than men, particularly in low- and lower-middle-income economies. Associations between longer education and former alcohol use with dementia risk (RHR, 1.01 [1.00, 1.03] per year, and 0.55 [0.38, 0.79], respectively) were stronger for men than women; otherwise, there were no discernible sex differences in other RFs.

DISCUSSION

Dementia risk was higher in women than men, with possible variations by country-level income settings, but most RFs appear to work similarly in women and men.

A task force for diagnosis and treatment of people with Alzheimer's disease in Latin America

Alzheimer's disease (AD) represents a substantial burden to patients, their caregivers, health systems, and society in Latin America and the Caribbean (LAC). This impact is exacerbated by limited access to diagnosis, specialized care, and therapies for AD within and among nations. The region has varied geographic, ethnic, cultural, and economic conditions, which create unique challenges to AD diagnosis and management. To address these issues, the Americas Health Foundation convened a panel of eight neurologists, geriatricians, and psychiatrists from Argentina, Brazil, Colombia, Ecuador, Guatemala, Mexico, and Peru who are experts in AD for a three-day virtual meeting to discuss best practices for AD diagnosis and treatment in LAC and create a manuscript offering recommendations to address identified barriers. In LAC, several barriers hamper diagnosing and treating people with dementia. These barriers include access to healthcare, fragmented healthcare systems, limited research funding, unstandardized diagnosis and treatment, genetic heterogeneity, and varying social determinants of health. Additional training for physicians and other healthcare workers at the primary care level, region-specific or adequately adapted cognitive tests, increased public healthcare insurance coverage of testing and treatment, and dedicated search strategies to detect populations with gene variants associated with AD are among the recommendations to improve the landscape of AD.

The (in)visible Brazilians: A perspective review on the need for brain health and dementia research with Brazilian immigrants in the United States

Introduction

The Brazilian population in the United States (U.S.), a Latinx subgroup, is rapidly growing and aging but remains underrepresented in U.S. health research. In addition to group-specific genetic and environmental risks, Brazilian immigrants and their offspring in the U.S. likely have cumulative risks for health inequities.It is estimated that 71% of Brazilian immigrants in the U.S. are undocumented, which may limit healthcare access/utilization. Furthermore, mental health is reported as a health priority by Brazilian immigrants in the U.S., and there is a lack of research on Alzheimer's disease and related dementia (AD/ADRD) in this population.

Methods

We reviewed the scientific literature using traditional (e.g., PubMed) sources and databases generated by U.S. and Brazilian governments, as well as international organizations, and press articles.

Results

This perspective review lists recommendations for researchers, health providers, and policymakers to promote greater inclusion of U.S. Brazilian populations in health research and care. The review identifies research areas in need of attention to address health inequities and promote mental/brain health in Brazilian immigrants and their offspring living in the U.S. These research areas are: 1) epidemiological studies to map the prevalence and incidence of mental/brain health conditions; 2) research on aging and AD/ADRD risk factors among Brazilian populations in the U.S.; and 3) the need for greater representation of U.S-residing Brazilian population in other relevant research areas involving genetics, neuropathology, and clinical trials.

Conclusions

The recommendation and research efforts proposed should help to pave the way for the development of community-engagement research and to promote mental/brain health education, improvement of mental/brain health and AD/ADRD services, and the development of culturally-informed intervention to the U.S.-residing Brazilian communities.

HIGHLIGHTS

The Brazilian population in the United States is growing but is underrepresented in U.S. health research.Approximately 71% of Brazilian immigrants in the United States are undocumented, with an increased risk for health inequities.Mental health is reported as a central health priority by Brazilian immigrants in the United States.There is a lack of research on Alzheimer's disease and other dementias (ADRD) in Brazilian immigrants in the United States.Epidemiological research is needed to map the prevalence/incidence of mental health conditions and ADRD risk factors among Brazilian immigrants in the United States.

Education and cognitive function among older adults in Brazil and Mexico

Education is protective against cognitive impairment. We used nationally representative data from Mexico and Brazil to assess the association between education and cognitive function. The sample included adults ≥ 50 years from the Brazilian Longitudinal Study of Aging (ELSI) and the Mexican Health and Aging Study (MHAS). Participants were classified as cognitively impaired or not impaired. We used logistic regression models to estimate the association between education and cognitive function. Education level was higher in MHAS than in ELSI. Participants with at least 1 year of education were less likely to have cognitive impairment than those with no formal education in both cohorts. Men in ELSI had higher odds for cognitive impairment compared to men in MHAS. In both cohorts, higher educational level was associated with lower odds of cognitive impairment compared to no formal education. Sex was an effect modifier in MHAS but not in ELSI.

HIGHLIGHTS

Cognitive test batteries were harmonized using a regression-based approach.Even very low levels of education were associated with reduced odds of cognitive impairment compared to no formal education.Brazilians were more likely to have cognitive impairment than Mexicans given the same education level.The differences in the association of education with cognition between Brazil and Mexico were only observed among men.

Literacy, but not memory, is associated with hippocampal connectivity in illiterate adults

Background

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 MRI and an episodic memory test (Free and Cued Selective Reminding Test). Illiteracy was defined as a TOFHLA score below 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 Black (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. Interestingly, 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.

Conclusions

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

Social participation and risk of developing dementia

The increasing number of people with dementia globally illustrates the urgent need to reduce dementia's scale and impact. Lifetime social participation may affect dementia risk by increasing cognitive reserve, and through brain maintenance by reducing stress and improving cerebrovascular health. It may therefore have important implications for individual behavior and public health policy aimed at reducing dementia burden. Observational study evidence indicates that greater social participation in midlife and late life is associated with 30-50% lower subsequent dementia risk, although some of this may not be causal. Social participation interventions have led to improved cognition but, partly due to short follow-up and small numbers of participants, no reduction in risk of dementia. We summarize the evidence linking social participation with dementia, discuss potential mechanisms by which social participation is likely to reduce and mitigate the impact of neuropathology in the brain, and consider the implications for future clinical and policy dementia prevention interventions.