Clinical and neuroimaging risk factors for cognitive decline in community-dwelling older adults living in rural Ecuador. A population-based prospective cohort study

Cognitive performance and all-cause mortality in community dwellers of Amerindian ancestry living in rural Ecuador: A population-based, longitudinal prospective study

OBJECTIVE

There is limited information on mortality risk in individuals with cognitive impairment living in rural Latin America. In this study, we assess the association between cognitive impairment and all-cause mortality in adults of Amerindian ancestry living in rural Ecuador.

PATIENTS AND METHODS

Middle-aged and older adults enrolled in the population-based Three Villages Study cohort were followed prospectively in order to estimate mortality risk according to their baseline cognitive performance as determined by the Montreal Cognitive Assessment (MoCA). Results were adjusted for demographics, level of education, traditional cardiovascular risk factors, symptoms of depression, severe tooth loss, and oily fish intake (factors previously associated with mortality in the study population).

RESULTS

Analysis included 1022 individuals followed for an average of 7.8 ± 3.4 years. Mean MoCA score was 21.2 ± 5.4 points (median: 22 points), with 334 (32.7%) individuals showing cognitive impairment, as evidenced by a MoCA score ≤ 19 points (the cutoff for poor cognitive performance based on previous studies in the same population). A total of 150 (14.7%) individuals died during the follow-up. Crude mortality rate was 2.87 per 100 person-years (95% C.I.: 2.08 - 3.96). For individuals with normal cognition, the mortality rate was 1.21 (95% C.I.: 0.92 - 1.50) while for those with cognitive impairment the rate increased to 3.48 (95% C.I.: 2.73 - 4.23). A multivariate Cox-proportional hazards model, confirmed that individuals with cognitive impairment had a significantly higher mortality risk than those without cognitive impairment (HR: 1.52; 95% C.I.: 1.05 - 2.18).

CONCLUSIONS

Cognitive impairment is associated with mortality in the study population.

An objective model for diagnosing comorbid cognitive impairment in patients with epilepsy based on the clinical-EEG functional connectivity features

Objective

Cognitive impairment (CI) is a common disorder in patients with epilepsy (PWEs). Objective assessment method for diagnosing CI in PWEs would be beneficial in reality. This study proposed to construct a diagnostic model for CI in PWEs using the clinical and the phase locking value (PLV) functional connectivity features of the electroencephalogram (EEG).

Methods

PWEs who met the inclusion and exclusion criteria were divided into a cognitively normal (CON) group (n = 55) and a CI group (n = 76). The 23 clinical features and 684 PLV _EEG features at the time of patient visit were screened and ranked using the Fisher score. Adaptive Boosting (AdaBoost) and Gradient Boosting Decision Tree (GBDT) were used as algorithms to construct diagnostic models of CI in PWEs either with pure clinical features, pure PLV _EEG features, or combined clinical and PLV _EEG features. The performance of these models was assessed using a five-fold cross-validation method.

Results

GBDT-built model with combined clinical and PLV _EEG features performed the best with accuracy, precision, recall, F1-score, and an area under the curve (AUC) of 90.11, 93.40, 89.50, 91.39, and 0.95%. The top 5 features found to influence the model performance based on the Fisher scores were the magnetic resonance imaging (MRI) findings of the head for abnormalities, educational attainment, PLV _EEG in the beta (β)-band C3-F4, seizure frequency, and PLV _EEG in theta (θ)-band Fp1-Fz. A total of 12 of the top 5% of features exhibited statistically different PLV _EEG features, while eight of which were PLV _EEG features in the θ band.

Conclusion

The model constructed from the combined clinical and PLV _EEG features could effectively identify CI in PWEs and possess the potential as a useful objective evaluation method. The PLV _EEG in the θ band could be a potential biomarker for the complementary diagnosis of CI comorbid with epilepsy.

Carotid Intima-Media Thickness (cIMT) and Cognitive Performance: A Population-Based Cross-Sectional Study From North India

INTRODUCTION

Atherosclerosis has been shown to impact cognitive impairment, with most of the evidence originating from European, African, or East Asian populations that have employed carotid intima-media thickness (cIMT) as a biomarker for atherosclerosis. Vascular disease is related to dementia/cognitive decline. There is no community-based study from India that has looked at the association of cIMT with cognitive performance.

METHODS

In this cross-sectional study between December 2014 and 2019, we recruited 7505 persons [(mean age 64.6 (9.2) y) and 50.9% women] from a community-dwelling population in New Delhi. These persons underwent carotid ultrasound to quantify cIMT and a cognitive test battery that tapped into memory, processing speed, and executive function. We also computed the general cognitive factor (g-factor), which was identified as the first unrotated component of the principal component analysis and explained 37.4% of all variances in the cognitive tests. We constructed multivariate linear regression models adjusted for age, sex, education, and cardiovascular risk factors. Additional adjustment was made for depression, anxiety, and psychosocial support in the final model.

RESULTS

We found a significant association of higher cIMT with worse performance in general cognition (β=-0. 01(95% CI: -0.01; -0.01); P<0.001), processing speed (β=-0.20; 95% CI: -0.34; -0.07); P=0.003), memory (β=-0.29; 95% CI: -0.53; -0.05); P=0.016), and executive function (β=-0.54; 95% CI: -0.75; -0.33); P=<0.001). There was no statistically significant association of cIMT with Mini-Mental Status Examination score (β=0.02; 95% CI: -0.34; 0.40; 0.89).

CONCLUSION

The cross-sectional study found significant associations of increased cIMT with worse performance in global cognition, information processing, memory, and executive function.

The global burden of cerebral small vessel disease in low- and middle-income countries: A systematic review and meta-analysis

BACKGROUND

Cerebral small vessel disease (cSVD) is a major cause of stroke and dementia. Previous studies on the prevalence of cSVD are mostly based on single geographically defined cohorts in high-income countries. Studies investigating the prevalence of cSVD in low- and middle-income countries (LMICs) are expanding but have not been systematically assessed.

AIM

This study aims to systematically review the prevalence of cSVD in LMICs.

RESULTS

Articles were searched from the Ovid MEDLINE and EMBASE databases from 1 January 2000 to 31 March 2022, without language restrictions. Title/abstract screening, full-text review, and data extraction were performed by two to seven independent reviewers. The prevalence of cSVD and study sample size were extracted by pre-defined world regions and health status. The Risk of Bias for Non-randomized Studies tool was used. The protocol was registered on PROSPERO (CRD42022311133). A meta-analysis of proportion was performed to assess the prevalence of different magnetic resonance imaging markers of cSVD, and a meta-regression was performed to investigate associations between cSVD prevalence and type of study, age, and male: female ratio. Of 2743 studies identified, 42 studies spanning 12 global regions were included in the systematic review. Most of the identified studies were from China (n = 23). The median prevalence of moderate-to-severe white matter hyperintensities (WMHs) was 20.5%, 40.5%, and 58.4% in the community, stroke, and dementia groups, respectively. The median prevalence of lacunes was 0.8% and 33.5% in the community and stroke groups. The median prevalence of cerebral microbleeds (CMBs) was 10.7% and 22.4% in the community and stroke groups. The median prevalence of moderate-to-severe perivascular spaces was 25.0% in the community. Meta-regression analyses showed that the weighted median age (51.4 ± 0.0 years old; range: 36.3-80.2) was a significant predictor of the prevalence of moderate-to-severe WMH and lacunes, while the type of study was a significant predictor of the prevalence of CMB. The heterogeneity of studies was high (>95%). Male participants were overrepresented.

CONCLUSIONS

This systematic review and meta-analysis provide data on cSVD prevalence in LMICs and demonstrated the high prevalence of the condition. cSVD research in LMICs is being published at an increasing rate, especially between 2010 and 2022. More data are particularly needed from Sub-Saharan Africa and Central Europe, Eastern Europe, and Central Asia.

Social determinants of health and cognitive performance of older adults living in rural communities: The Three Villages Study

OBJECTIVES

There is limited information on factors associated with poor cognitive performance in rural settings of Low- and Middle-Income Countries. Using the Three Villages Study Cohort, we assessed whether social determinants of health (SDH) play a role in cognitive performance among older adults living in rural Ecuador.

METHODS

Atahualpa, El Tambo and Prosperidad residents aged ≥60 years received measurement of SDH by means of the Gijon Scale together with a Montreal Cognitive Assessment (MoCA). The association between SDH and cognitive performance (dependent variable) was assessed by generalized linear models, adjusted for demographics, years of education, cardiovascular risk factors, symptoms of depression and biomarkers of structural brain damage.

RESULTS

We included 513 individuals (mean age: 67.9 ± 7.3 years; 58% women). The mean score on the Gijon scale was 9.9 ± 2.9 points, with 237 subjects classified as having a high social risk (≥10 points). The mean MoCA score was 19.6 ± 5.4 points. Locally weighted scatterplot smoothing showed an inverse linear relationship between SDH and MoCA scores. SDH and MoCA scores were inversely associated in linear models adjusted for clinical covariates (β: -0.17; 95% C.I.: -0.32 to -0.02; p = 0.020), neuroimaging covariates (β: -0.17; 95% C.I.: -0.31 to -0.03; p = 0.018), as well as in the most parsimonious model (β: -0.16; 95% C.I.: -1.30 to -0.02; p = 0.026).

CONCLUSIONS

Study results provide robust evidence of an inverse association between SDH and cognitive performance. Interventions and programs aimed to reduce disparities in the social risk of older adults living in underserved rural populations may improve cognitive performance in these individuals.

Cognitive decline among individuals with history of mild symptomatic SARS-CoV-2 infection: A longitudinal prospective study nested to a population cohort

BACKGROUND AND PURPOSE

Neurological complications of SARS-CoV-2 infection are noticed among critically ill patients soon after disease onset. Information on delayed neurological sequelae of SARS-CoV-2 infection is nil. Following a longitudinal study design, the occurrence of cognitive decline among individuals with a history of mild symptomatic SARS-CoV-2 infection was assessed.

METHODS

Stroke- and seizure-free Atahualpa residents aged ≥40 years, who had pre-pandemic cognitive assessments as well as normal brain magnetic resonance imaging and electroencephalogram recordings, underwent repeated evaluations 6 months after a SARS-CoV-2 outbreak infection in Atahualpa. Patients requiring oxygen therapy, hospitalization, and those who had initial neurological manifestations were excluded. Cognitive decline was defined as a reduction in the Montreal Cognitive Assessment (MoCA) score between the post-pandemic and pre-pandemic assessments that was ≥4 points greater than the reduction observed between two pre-pandemic MoCAs. The relationship between SARS-CoV-2 infection and cognitive decline was assessed by fitting logistic mixed models for longitudinal data as well as exposure-effect models.

RESULTS

Of 93 included individuals (mean age 62.6 ± 11 years), 52 (56%) had a history of mild symptomatic SARS-CoV-2 infection. Post-pandemic MoCA decay was worse in seropositive individuals. Cognitive decline was recognized in 11/52 (21%) seropositive and 1/41 (2%) seronegative individuals. In multivariate analyses, the odds for developing cognitive decline were 18.1 times higher among SARS-CoV-2 seropositive individuals (95% confidence interval 1.75-188; p = 0.015). Exposure-effect models confirmed this association (β = 0.24; 95% confidence interval 0.07-0.41; p = 0.006).

CONCLUSIONS

This study provides evidence of cognitive decline among individuals with mild symptomatic SARS-CoV-2 infection. The pathogenesis of this complication remains unknown.

Cerebrovascular Correlates of Dementia in Community-Dwelling Older Adults Living in Rural Communities - The Three Villages Study. Rationale and Protocol of a Population-Based Prospective Cohort Study

BACKGROUND

Despite the assumption that dementia is increasing in rural areas of Latin America, there is no information on the burden and risk factors leading to dementia in these settings.

AIMS

To assess prevalence and incidence of dementia, and its cerebrovascular correlates in an established cohort of community-dwelling older adults living in rural Ecuador, and to explore the impact of dementia on functional disability and the role of the social determinants of health in the above-mentioned relationships.

DESIGN

Population-based, cohort study with cross-sectional and longitudinal components. Baseline clinical interviews will focus on the assessment of cognitive performance and dementia by means of the clinical dementia rating scale (CDRS). Functional disability and social determinants of health will be correlated with CDRS scores. In addition, participants will undergo interviews and procedures to assess cardiovascular risk factors and signatures of brain damage, cerebral small vessel disease, and other stroke subtypes. The CDRS and the Functional Activities Questionnaire will be administered every year to assess the rate of incident dementia and the severity of functional disability. Neuroimaging studies will be repeated at the end of the study (5 years) to assess the impact of newly appeared cerebral and vascular lesions on cognitive decline.

COMMENT

This study will allow determine whether cerebrovascular diseases are in the path of dementia development in these rural settings. This may prove cost-effective for the development of preventive strategies aimed to control modifiable factors and reduce disability in patients with dementia living in underserved populations.

Cognitive decline is not influenced by the marital status or living arrangements in community-dwelling adults living in a rural setting. A population-based prospective cohort study

Little is known on factors influencing cognitive decline in rural communities. Using the Atahualpa Project cohort, we aimed to assess whether the marital status or living arrangements influenced cognitive decline in community-dwelling adults living in an Ecuadorian rural village. The study included 629 Atahualpa residents aged ≥40 years who had a follow-up Montreal Cognitive Assessment (MoCA) repeated at least one year after baseline. Multivariate longitudinal linear models were fitted to assess differences between the marital status and living arrangements and cognitive decline (as the outcome). A total of 411 participants were married. The remaining 218 were either single, divorced or widowed (191 of them lived with family members and the others lived alone). Enrolled individuals contributed 2088.4 person-years of follow-up (mean: 3.3 ± 1.1 years). The mean baseline MoCA was 22.1 ± 4.5 points and the follow-up MoCA was 20.6 ± 4.8 points (p = 0.001). Overall, 394 (63%) individuals had lower MoCA scores at follow-up. A fully-adjusted longitudinal linear model showed no differences in MoCA decline across married and non-married individuals (β: -0.15; 95% C.I.: -0.55 - 0.26; p = 0.477). When the subset of non-married individuals was taken into account for analyses, multivariate longitudinal linear models showed no differences in the severity of cognitive decline across individuals living alone versus those living with family members (β: 0.28; 95% C.I.: -0.68 - 1.24; p = 0.572). In this study, the marital status or living arrangements had no influence on cognitive decline in the follow-up.