Global, regional, and national burden of Alzheimer's disease and other dementias, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016

Cognitively healthy centenarians are genetically protected against Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) prevalence increases with age, yet a small fraction of the population reaches ages > 100 years without cognitive decline. We studied the genetic factors associated with such resilience against AD.

METHODS

Genome-wide association studies identified 86 single nucleotide polymorphisms (SNPs) associated with AD risk. We estimated SNP frequency in 2281 AD cases, 3165 age-matched controls, and 346 cognitively healthy centenarians. We calculated a polygenic risk score (PRS) for each individual and investigated the functional properties of SNPs enriched/depleted in centenarians.

RESULTS

Cognitively healthy centenarians were enriched with the protective alleles of the SNPs associated with AD risk. The protective effect concentrated on the alleles in/near ANKH, GRN, TMEM106B, SORT1, PLCG2, RIN3, and APOE genes. This translated to >5-fold lower PRS in centenarians compared to AD cases (P = 7.69 × 10-71), and 2-fold lower compared to age-matched controls (P = 5.83 × 10-17).

DISCUSSION

Maintaining cognitive health until extreme ages requires complex genetic protection against AD, which concentrates on the genes associated with the endolysosomal and immune systems.

HIGHLIGHTS

Cognitively healthy cent enarians are enriched with the protective alleles of genetic variants associated with Alzheimer's disease (AD). The protective effect is concentrated on variants involved in the immune and endolysosomal systems. Combining variants into a polygenic risk score (PRS) translated to > 5-fold lower PRS in centenarians compared to AD cases, and ≈ 2-fold lower compared to middle-aged healthy controls.

Bidirectional two-sample Mendelian randomization analyses support causal relationships between structural and diffusion imaging-derived phenotypes and the risk of major neurodegenerative diseases

Previous observational investigations suggest that structural and diffusion imaging-derived phenotypes (IDPs) are associated with major neurodegenerative diseases; however, whether these associations are causal remains largely uncertain. Herein we conducted bidirectional two-sample Mendelian randomization analyses to infer the causal relationships between structural and diffusion IDPs and major neurodegenerative diseases using common genetic variants-single nucleotide polymorphism (SNPs) as instrumental variables. Summary statistics of genome-wide association study (GWAS) for structural and diffusion IDPs were obtained from 33,224 individuals in the UK Biobank cohort. Summary statistics of GWAS for seven major neurodegenerative diseases were obtained from the largest GWAS for each disease to date. The forward MR analyses identified significant or suggestively statistical causal effects of genetically predicted three structural IDPs on Alzheimer's disease (AD), frontotemporal dementia (FTD), and multiple sclerosis. For example, the reduction in the surface area of the left superior temporal gyrus was associated with a higher risk of AD. The reverse MR analyses identified significantly or suggestively statistical causal effects of genetically predicted AD, Lewy body dementia (LBD), and FTD on nine structural and diffusion IDPs. For example, LBD was associated with increased mean diffusivity in the right superior longitudinal fasciculus and AD was associated with decreased gray matter volume in the right ventral striatum. Our findings might contribute to shedding light on the prediction and therapeutic intervention for the major neurodegenerative diseases at the neuroimaging level.

Matrix Remodeling Enzymes as Potential Fluid Biomarkers of Neurodegeneration in Alzheimer's Disease

This study investigated the diagnostic accuracy of plasma biomarkers-specifically, matrix metalloproteinase (MMP-9), tissue inhibitor of metalloproteinase (TIMP-1), CD147, and the MMP-/TIMP-1 ratio in patients with Alzheimer's disease (AD) dementia. The research cohort comprised patients diagnosed with probable AD dementia and a control group of cognitively unimpaired (CU) individuals. Neuroradiological assessments included brain magnetic resonance imaging (MRI) following dementia protocols, with subsequent volumetric analysis. Additionally, cerebrospinal fluid (CSF) AD biomarkers were classified using the A/T/N system, and apolipoprotein E (APOE) ε4 carrier status was determined. Findings revealed elevated plasma levels of MMP-9 and TIMP-1 in AD dementia patients compared to CU individuals. Receiver operating characteristic (ROC) curve analysis demonstrated significant differences in the areas under the curve (AUC) for MMP-9 (p < 0.001) and TIMP-1 (p < 0.001). Notably, plasma TIMP-1 levels were significantly lower in APOE ε4+ patients than in APOE ε4- patients (p = 0.041). Furthermore, APOE ε4+ patients exhibited reduced hippocampal volume, particularly in total, right, and left hippocampal measurements. TIMP-1 levels exhibited a positive correlation, while the MMP-9/TIMP-1 ratio showed a negative correlation with hippocampal volume parameters. This study sheds light on the potential use of TIMP-1 as a diagnostic marker and its association with hippocampal changes in AD.

Does Physical Exercise Modify the Pathophysiology of Alzheimer's Disease in Older Persons?

Physical exercise is well known for its benefits on brain health. However, the mechanisms through which these benefits occur remain discussed, especially in the context of cognitive conditions such as Alzheimer's disease. The present short review summarizes the findings of interventional studies that examined the effects of exercise training on the specific and non-specific biomarkers of Alzheimer's disease. Controlled exercise intervention studies published in the English language were selected if they assessed the effects of a physical exercise intervention of at least 2 weeks in middle-aged or older adults on one of the following biomarkers measured either in the brain, the cerebrospinal fluid or the blood: beta-amyloid, tau, neurofilament light chain, and glial fibrillary acidic protein. Overall, there was no strong evidence of significant effects of exercise interventions on any of the selected biomarkers. However, in specific populations, such as women with obesity, pre-diabetes, or depression, favorable changes in blood beta-amyloid concentrations were reported. Further benefits on cerebrospinal fluid beta-amyloid were also demonstrated in APOE-ε4 allele carriers with Alzheimer's disease. In conclusion, the current evidence suggests that physical exercise does not modulate the pathophysiology of Alzheimer's disease in the overall population of middle-aged and older adults. Nonetheless, some specific populations, such as women with metabolic disorders and Alzheimer's disease patients with APOE-ε4 genotype, seem to be favorably affected. Further studies, including long follow-ups, large sample sizes, and concomitantly assessing the effects of other factors such as sedentary behavior and diet, are required to bring further evidence to the field.

Association between Female Reproductive Factors and Risk of Dementia

Women have an over 50% greater risk of dementia than men, which is a main topic of much research. This review aims to investigate the impact of a woman's reproductive history on dementia risk. The consequences of stillbirth are long-term health and psychosocial problems for women. Because of the awareness of an endangered pregnancy, many parents experience deep anxiety and stress in subsequent pregnancies. There are contradictory conclusions from research about abortion and the risk of dementia correlation. When it comes to the late age of first birth, which is said to be above 35 years old, it was observed that older mothers have a decreased risk of dementia compared to those who gave birth in their 20s; however, being a child of the older mother is connected with a higher risk of developing dementia. Using hormonal contraception can result in decreased risk of dementia as estrogen stimulates microglia-related Aβ removal and reduces tau hyperphosphorylation. The influence of postmenopausal hormonal therapy and the duration of the reproductive period on developing dementia remains unclear. Although female disorders like endometriosis and polycystic ovary syndrome are reported to increase the risk of dementia, the research on this topic is very limited, especially when it comes to endometriosis, and needs further investigation. Interestingly, there is no conclusion on whether hypertensive disorders of pregnancy increase the risk of dementia, but most articles seem to confirm this theory.

Dementia Risk Awareness, Health Behaviors and Motivation for Dementia Prevention in Middle-Aged and Older Adults in Türkiye

This study aimed to investigate factors influencing motivation for dementia preventive behaviors in a population aged 40 and over. We conducted a descriptive cross-sectional study between December 2022 and May 2023, involving 483 participants in an online survey. We collected data on dementia risk awareness, healthy lifestyle choices, and motivation for dementia risk reduction. The majority of respondents, comprising 41.6%, demonstrated a moderate level of risk awareness, with 50.5% believing that prevention is beyond anyone's control. Motivations for lifestyle change were significantly higher in women (p < .001) and `participants with university degree education (p < .05). Regression analysis identified gender (female), education level (higher education), and dementia risk awareness, emerged as significant predictors of motivation to change lifestyle (beta: .138, beta: .136, beta: .114, p < .001, respectively). This study underscores the importance of risk awareness in motivating dementia prevention, suggesting avenues for future research to explore specific determinants of motivation to reduce dementia risks.

Global trends and hotspots in research on acupuncture for neurodegenerative diseases over the last decade: a bibliometric and visualization analysis

Objectives

This study aimed to explore the current status and trends of acupuncture for neurodegenerative diseases (NDs) in the last decade and provide new insights for researchers in future studies.

Methods

The publications concerning acupuncture treatment for NDs published between 2014 and 2023 were extracted from the Web of Science Core Collection. We used CiteSpace and VOSviewer to analyze data on numbers of annual publications, countries, institutions, cited journals, cited authors, cited references, keywords, and citation bursts about acupuncture for NDs.

Results

A total of 635 publications were obtained from 2014 to 2023. We identified the most prolific journals, countries, institutions, authors, patterns of authorship, and the main direction of future research in the field of acupuncture for NDs in the last decade. The country, institution, and journal with the most publications are China (389 articles), Beijing University of Chinese Medicine (56 articles), and Evidence Based Complementary and Alternative Medicine (42 articles), respectively. The high-frequency keywords focused on "Alzheimer's disease," "Parkinson's disease," "acupuncture," "dementia," and "electroacupuncture." The top five keywords in terms of centrality were "cerebral ischemia," "acupuncture stimulation," "fMRI," "apoptosis," and "deep brain stimulation."

Conclusion

The results from this bibliometric study provide insight into the research trends in acupuncture therapy for NDs, and the current status and trends of the past decade, which may help researchers confirm the current status, hotspots, and frontier trends in this field.

Constructing personalized characterizations of structural brain aberrations in patients with dementia using explainable artificial intelligence

Deep learning approaches for clinical predictions based on magnetic resonance imaging data have shown great promise as a translational technology for diagnosis and prognosis in neurological disorders, but its clinical impact has been limited. This is partially attributed to the opaqueness of deep learning models, causing insufficient understanding of what underlies their decisions. To overcome this, we trained convolutional neural networks on structural brain scans to differentiate dementia patients from healthy controls, and applied layerwise relevance propagation to procure individual-level explanations of the model predictions. Through extensive validations we demonstrate that deviations recognized by the model corroborate existing knowledge of structural brain aberrations in dementia. By employing the explainable dementia classifier in a longitudinal dataset of patients with mild cognitive impairment, we show that the spatially rich explanations complement the model prediction when forecasting transition to dementia and help characterize the biological manifestation of disease in the individual brain. Overall, our work exemplifies the clinical potential of explainable artificial intelligence in precision medicine.

Antiviral Treatment and Response are Associated With Lower Risk of Dementia Among Hepatitis C Virus-Infected Patients

OBJECTIVE

Eradication of hepatitis C virus (HCV) infection has been linked with improvement in neurocognitive function, but few studies have evaluated the effect of antiviral treatment/ response on risk of dementia. Using data from the Chronic Hepatitis Cohort Study (CHeCS), we investigated how antiviral therapy impacts the risk of developing dementia among patients with HCV.

METHODS

A total of 17,485 HCV patients were followed until incidence of dementia, death, or last follow-up. We used an extended landmark modeling approach, which included time-varying covariates and propensity score justification for treatment selection bias, as well as generalized estimating equations (GEE) with a link function as multinominal distribution for a discrete time-to-event data. Death was considered a competing risk.

RESULTS

After 15 years of follow-up, 342 patients were diagnosed with incident dementia. Patients who achieved sustained virological response (SVR) had significantly decreased risk of dementia compared to untreated patients, with hazard ratios (HRs) of 0.32 (95% CI 0.22-0.46) among patients who received direct-acting antiviral (DAA) treatment and 0.41 (95% CI 0.26-0.60) for interferon-based (IFN) treatment. Risk reduction remained even when patients failed antiviral treatment (HR 0.38, 95% CI 0.38-0.51). Patients with cirrhosis, Black/African American patients, and those without private insurance were at significantly higher risk of dementia.

CONCLUSION

Antiviral treatment independently reduced the risk of dementia among HCV patients, regardless of cirrhosis. Our findings support the importance of initiation antiviral therapy in chronic HCV-infected patients.

Identifying dementia from cognitive footprints in hospital records among Chinese older adults: a machine-learning study

Background

By combining theory-driven and data-driven methods, this study aimed to develop dementia predictive algorithms among Chinese older adults guided by the cognitive footprint theory.

Methods

Electronic medical records from the Clinical Data Analysis and Reporting System in Hong Kong were employed. We included patients with dementia diagnosed at 65+ between 2010 and 2018, and 1:1 matched dementia-free controls. We identified 51 features, comprising exposures to established modifiable factors and other factors before and after 65 years old. The performances of four machine learning models, including LASSO, Multilayer perceptron (MLP), XGBoost, and LightGBM, were compared with logistic regression models, for all patients and subgroups by age.

Findings

A total of 159,920 individuals (40.5% male; mean age [SD]: 83.97 [7.38]) were included. Compared with the model included established modifiable factors only (area under the curve [AUC] 0.689, 95% CI [0.684, 0.694]), the predictive accuracy substantially improved for models with all factors (0.774, [0.770, 0.778]). Machine learning and logistic regression models performed similarly, with AUC ranged between 0.773 (0.768, 0.777) for LASSO and 0.780 (0.776, 0.784) for MLP. Antipsychotics, education, antidepressants, head injury, and stroke were identified as the most important predictors in the total sample. Age-specific models identified different important features, with cardiovascular and infectious diseases becoming prominent in older ages.

Interpretation

The models showed satisfactory performances in identifying dementia. These algorithms can be used in clinical practice to assist decision making and allow timely interventions cost-effectively.

Funding

The Research Grants Council of Hong Kong under the Early Career Scheme 27110519.

Socioeconomic Status Transition Throughout Life and Risk of Dementia

Importance

Socioeconomic status (SES) is associated with dementia. However, the role of SES transitions in dementia is less explored; such evidence would be useful to understand whether social mobility is associated with healthy longevity at older ages.

Objective

To investigate the association of lifetime SES transition with risk of dementia.

Design, Setting, and Participants

This prospective cohort study, conducted from August 2010 to December 2016, used data from the Japan Gerontological Evaluation Study for participants aged 65 years or older from 31 different areas in Japan. Individuals with missing SES values, loss of follow-up, or new dementia onset 1 year or less from baseline were excluded. Data analysis was performed from April 2022 to April 2023.

Exposure

Transitions in SES across the life course.

Main Outcomes and Measures

The main outcome was risk of dementia incidence and corresponding loss or gain of dementia-free periods in a lifespan. The incidence of dementia was identified with a national registry of long-term nursing care services.

Results

A total of 9186 participants (4703 men [51.2%]) were included. The mean (SD) age at baseline was 74.2 (6.0) years. Six SES transitions were identified: upward, stable-high, upper-middle, lower-middle, downward, and stable-low. During the follow-up period, 800 cases of dementia were identified. Many dementia risk factors, including lifestyle behaviors, comorbidities, and social factors, were associated with SES transition patterns. Compared with lower-middle SES, the lowest risk of dementia was observed for upward transition (hazard ratio [HR], 0.66; 95% CI, 0.57-0.74) followed by stable-high (HR, 0.77; 95% CI, 0.69-0.86), downward (HR, 1.15; 95% CI, 1.09-1.23), and stable-low (HR 1.45; 95% CI, 1.31-1.61) transition (P <  .001 for linearity); there was no association of upper-middle transition with risk of dementia (HR, 0.91; 95% CI, 0.79-1.03). The greatest increases in dementia-free years in the lifespan were also associated with upward SES transition (eg, 1.8 years [95% CI, 1.4-2.2 years] at age 65 years), while the downward transition was associated with the largest loss in lifetime dementia-free years at 75 years or older (eg, -1.4 years [95% CI, -2.4 to -0.4 years] at age 85 years).

Conclusions and Relevance

This cohort study of Japanese older adults identified that upward and downward SES transitions were associated with risk of dementia and the length of dementia-free periods over the lifespan. The results may be useful to understand the association between social mobility and healthy longevity.

Uncovering the extent of dementia prevalence in Iran: a comprehensive systematic review and meta-analysis

BACKGROUND

Dementia is one of the major causes of disability and dependency among older people worldwide. The formation of an aging population in Iran can be associated with societal problems, including age-related disorders such as dementia. This study aimed to estimate the prevalence of dementia& Alzheimer disease in adults aged 60 years or older and it's its geographical distribution in Iran.

METHODS

A systematic review and meta-analysis study included articles published in both English and Persian languages and utilized various databases including: Google Scholar, PubMed, Web of Science, Magiran, and thesis database of medicine universities up to December 2022. The pooled prevalence was calculated using random effects models. The prevalence was reported separately for different geographical locations and types of area sampling, and age adjustment was performed for the selected studies. All statistical analyses were conducted using metaprop package in STATA version 17. The I2 statistic was applied to assess heterogeneity.

RESULTS

The meta-analysis considered nine relevant studies that were carried out up to 2023 in Iran. The study found that the prevalence of dementia in central and east counties was estimated to be 0.14 (95% CI; 0.04-0.31), while in western counties, the prevalence was estimated to be 0.1 (95%CI; 0.01-0.27). The estimated overall crude prevalence of dementia was estimated at 0.14 (95% CI; 0.03-0.31). Estimated prevalence-based health centers sampling and hospital-based studies were 0.02 (95% CI; 0.02-0.03), 0.05 (95% CI 0.06-0.11), respectively. One study used nursing home sampling as the sampling method, and the estimated prevalence was 0.43 (95%CI 0.38-0.49).

CONCLUSION

This is the first systematic review and meta-analysis of the prevalence of dementia's disease up to 2023 in Iran. The estimated overall prevalence of dementia is lower than the reported prevalence in European countries and similar to other Asian countries.

Polypharmacy and associated factors in South Korean elderly patients with dementia: An analysis using National Health Insurance claims data

BACKGROUND

Dementia is accompanied by several symptoms, including cognitive function decline, as well as behavioral and psychological symptoms. Elderly patients with dementia often experience polypharmacy, the concurrent use of multiple medications, due to chronic comorbidities. However, research on polypharmacy in patients with dementia is limited. This study aimed to characterize polypharmacy and associated factors among elderly patients with dementia in South Korea, and compare the characteristics of patients with and without dementia patients.

METHODS

From the National Health Insurance Service (NHIS)-Senior cohort database, we extracted data on patients aged≥60 years who received outpatient treatment in 2019. Polypharmacy was defined as the concurrent use of five or more different oral medications for ≥90 days; excessive polypharmacy referred to the concurrent use of ten or more different oral medications for ≥90 days. We compared the prevalence of polypharmacy between patients with and without and identified the associated factors using a logistic regression model.

RESULTS

About 70.3% and 23.7% of patients with dementia exhibited polypharmacy and excessive polypharmacy, respectively. After adjusting for conditions such as age and Charlson's comorbidity index, the likelihood of polypharmacy and excessive polypharmacy significantly increased over time after the diagnosis of dementia. Additionally, under the same conditions, Medical Aid beneficiaries with dementia were more likely to experience polypharmacy and excessive polypharmacy compared to patients with dementia covered by National Health Insurance (NHI).

CONCLUSION

This study reports the latest evidence on the status and risk factors of polypharmacy in elderly patients with dementia. We proposed that careful monitoring and management are required for patients at high risk for polypharmacy.

Association of cognitive impairment with the interaction between chronic kidney disease and depression: findings from NHANES 2011-2014

BACKGROUND

Cognitive impairment (CoI), chronic kidney disease (CKD), and depression are prevalent among older adults and are interrelated, imposing a significant disease burden. This study evaluates the association of CKD and depression with CoI and explores their potential interactions.

METHOD

Data for this study were sourced from the 2011-2014 National Health and Nutritional Examination Survey (NHANES). Multiple binary logistic regression models assessed the relationship between CKD, depression, and CoI while controlling for confounders. The interactions were measured using the relative excess risk of interaction (RERI), the attributable proportion of interaction (AP), and the synergy index (S).

RESULTS

A total of 2,666 participants (weighted n = 49,251,515) were included in the study, of which 700 (16.00%) had CoI. After adjusting for confounding factors, the risk of CoI was higher in patients with CKD compared to non-CKD participants (odds ratio [OR] = 1.49, 95% confidence interval [CI]:1.12-1.99). The risk of CoI was significantly increased in patients with depression compared to those without (OR = 2.29, 95% CI: 1.73-3.03). Furthermore, there was a significant additive interaction between CKD and depression in terms of the increased risk of CoI (adjusted RERI = 2.01, [95% CI: 0.31-3.71], adjusted AP = 0.50 [95% CI: 0.25-0.75], adjusted S = 2.97 [95% CI: 1.27-6.92]).

CONCLUSION

CKD and depression synergistically affect CoI, particularly when moderate-to-severe depression co-occurs with CKD. Clinicians should be mindful of the combined impact on patients with CoI. Further research is needed to elucidate the underlying mechanisms and assess the effects specific to different CKD stages.

Longitudinal validation of cognitive reserve proxy measures: a cohort study in a rural Chinese community

BACKGROUND

While evidence supports cognitive reserve (CR) in preserving cognitive function, longitudinal validation of CR proxies, including later-life factors, remains scarce. This study aims to validate CR's stability over time and its relation to cognitive function in rural Chinese older adults.

METHODS

Within the project on the health status of rural older adults (HSRO), the survey included baseline assessment (2019) and follow-up assessment (2022). 792 older adults (mean age: 70.23 years) were followed up. The confirmatory factor analysis (CFA) was constructed using cognitive reserve proxies that included years of formal education, social support, hobbies, and exercise. We examined the longitudinal validity of the CR factor using confirmatory factor analyses and measurement invariance and explored the association of CR with cognition using Spearman's correlation and Generalized Estimating Equations (GEE).

RESULTS

The results showed that CR's CFA structure was stable over time (T0, χ2/df: 3.21/2; RMSEA: 0.02, and T1, χ2/df: 7.47/2; RMSEA: 0.05) and that it accepted both configural and metric invariance (Δχ2/df = 2.28/3, P = 0.52). In addition, it was found that CR had a stable positive relationship with cognitive function across time (T0, r = 0.54; T1, r = 0.49). Furthermore, longitudinal CR were associated with MMSE (β = 2.25; 95%CI = 2.01 ~ 2.49).

CONCLUSIONS

This study provided valuable evidence on the stability and validity of cognitive reserve proxy measures in rural Chinese older adults. Our findings suggested that cognitive reserve is associated with cognitive function over time and highlighted the importance of accumulating cognitive reserve in later life.

Cluster analysis dissecting cognitive deficits in older adults with major depressive disorder and the association with neurofilament light chain

BACKGROUND

Cognitive impairment is a growing problem with increasing burden in global aging. Older adults with major depressive disorder (MDD) have higher risk of dementia. Neurofilament light chain (NfL) has been proven as a potential biomarker in neurodegenerative disease, including dementia. We aimed to investigate the association between cognitive deficits and NfL levels in older adults with MDD.

METHODS

In this cross-sectional study, we enrolled 39 MDD patients and 15 individuals with mild neurocognitive disorder or major neurocognitive disorder, Alzheimer's type, as controls, from a tertiary psychiatric hospital. Both groups were over age 65 and with matched Mini-Mental State Examination (MMSE) score. Demographic data, clinical variables, and plasma NfL levels were obtained. We used cluster analysis according to their cognitive profile and estimated the correlation between plasma NfL levels and each cognitive domain.

RESULTS

In the MDD group, participants had higher rate of family psychiatry history and current alcohol use habit compared with controls. Control group of neurocognitive disorders showed significantly lower score in total MMSE and higher plasma NfL levels. Part of the MDD patients presented cognitive deficits clustered with that of neurocognitive disorders (cluster A). In cluster A, the total MMSE score (r=-0.58277, p=0.0287) and the comprehension domain (r=-0.71717, p=0.0039) were negatively correlated to NfL levels after adjusting for age, while the associations had not been observed in the other cluster.

CONCLUSIONS

We noted the negative correlation between NfL levels and cognition in MDD patients clustered with neurodegenerative disorder, Alzheimer's type. NfL could be a promising candidate as a biomarker to predict subtype of patients in MDD to develop cognitive decline. Further longitudinal studies and within MDD cluster analysis are required to validate our findings for clinical implications.

Intertwined depressive and cognitive trajectories and the risk of dementia and death in older adults: a competing risk analysis

Background

Depressive symptoms and cognitive impairment often interact, rendering their associations controversial. To date, their joint trajectories and associations with dementia and death remain underexplored.

Aims

To explore the interactions between depressive symptoms and cognitive function, their developmental trajectories and the associations with all-cause dementia, Alzheimer's disease (AD) and all-cause death in older adults.

Methods

Data were from the Health and Retirement Study. Depressive symptoms and cognitive function were measured using the 8-item Centre for Epidemiologic Studies Depression Scale and the Telephone Interview of Cognitive Status, respectively. All-cause dementia and AD were defined by self-reported or proxy-reported physician diagnoses. All-cause death was determined by interviews. The restricted cubic spline, group-based trajectory modelling and subdistribution hazard regression were used.

Results

Significant interactions between depressive symptoms and cognitive function in 2010 in their association with new-onset all-cause dementia and AD from 2010 to 2020 were found, especially in women (p for interaction <0.05). Independent trajectory analysis showed that emerging or high (vs no) depressive trajectories and poor or rapidly decreased cognitive trajectories (vs very good) from 1996 to 2010 were at significantly higher risk of subsequent all-cause dementia, AD and all-cause death. 15 joint trajectories of depressive symptoms and cognitive function from 1996 to 2010 were determined, where rapidly decreased cognitive function was more common in those with no depressive symptoms. Compared with older adults with the trajectory of no depressive symptoms and very good cognitive function, those with the trajectory of no depressive symptoms but rapidly decreased cognitive function were much more likely to develop new-onset all-cause dementia and death, with subdistribution hazard ratios (95% confidence intervals) of 4.47 (2.99 to 6.67) and 1.84 (1.43 to 2.36), especially in women.

Conclusions

To effectively mitigate the risk of dementia and death, it is crucial to acknowledge the importance of preventing cognitive decline in older adults without depressive symptoms, particularly in women.

Innate immune activation in neurodegenerative diseases

Activation of the innate immune system following pattern recognition receptor binding has emerged as one of the major pathogenic mechanisms in neurodegenerative disease. Experimental, epidemiological, pathological, and genetic evidence underscores the meaning of innate immune activation during the prodromal as well as clinical phases of several neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and frontotemporal dementia. Importantly, innate immune activation and the subsequent release of inflammatory mediators contribute mechanistically to other hallmarks of neurodegenerative diseases such as aberrant proteostatis, pathological protein aggregation, cytoskeleton abnormalities, altered energy homeostasis, RNA and DNA defects, and synaptic and network disbalance and ultimately to the induction of neuronal cell death. In this review, we discuss common mechanisms of innate immune activation in neurodegeneration, with particular emphasis on the pattern recognition receptors (PRRs) and other receptors involved in the detection of damage-associated molecular patterns (DAMPs).

Equine-assisted services for people living with dementia: a systematic review

BACKGROUND

Dementia has a significant impact on the social, physical, and psychological wellbeing of people living with dementia, their families and society. Animal-assisted interventions can have positive effects on the health and wellbeing of people living with dementia. Equine-assisted services are animal-assisted non-pharmacological interventions which have improved the health and wellbeing of diverse populations. The impact of participating in equine-assisted services on the health and wellbeing of people with dementia is unclear. A systematic review was conducted to synthesise evidence investigating the effects of participating in equine-assisted services on the health and wellbeing of people living with dementia.

DESIGN

Systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

METHODS

The databases CINAHL, EMBASE, MEDLINE, and Web of Science were searched for any research published prior to 14 June 2023. Peer-reviewed publications in the English language utilizing methods deriving quantitative and/or qualitative data were eligible. Methodological quality of included studies was assessed using the Mixed Methods Appraisal Tool. Findings from studies were synthesised using a deductive approach.

RESULTS

Of the 223 articles screened, six met the inclusion criteria: four quantitative and two qualitative studies. The six studies represent four separate equine interventions. Studies were of moderate to strong quality. Participants were people living with dementia (n = 44, mean age range 70-83 years), dementia care partners (n = 5, mean age 58), and equine-assisted services providers (n = 5). Interventions varied in duration, activities conducted, outcomes measured, and measurement tools used. Studies found a favourable impact of participating in equine-assisted services on the neuropsychiatric symptoms and quality of life of people living with dementia. Participating in equine-assisted services improved well-being, functional abilities, social participation, and communication, while also having a positive effect on social, emotional, and behavioural outcomes, and physical health.

CONCLUSIONS

The limited but high-quality literature investigating the impact of equine-assisted services among people living with dementia suggests that equine-assisted services can have a positive impact on the health and wellbeing of people living with dementia. Additional robust studies contributing to the evidence base are warranted; such studies can support the development of programs and further elucidate the impact of participation.

Perceived Threat of Alzheimer's Disease and Related Dementias Among Chinese Family Caregivers of Older Adults with Cognitive Impairment

Perceived threat of Alzheimer's disease and related dementias (ADRD) has been found a widespread phenomenon in developed countries, but has not yet been fully explored in developing countries. Analyzing data from 300 family caregivers of older adults with cognitive impairment in China, this study found caregiver burden was positively associated with the perceived threat of ADRD, and this association was buffered by higher family income and longer caregiving time. To alleviate undue ADRD concerns, it suggests expanding respite care and community elder care beds, and initiating education programs on reducing unnecessary worries about developing ADRD.

Advancements in Single-Cell RNA Sequencing Research for Neurological Diseases

Neurological diseases are a major cause of the global burden of disease. Although the mechanisms of the occurrence and development of neurological diseases are not fully clear, most of them are associated with cells mediating neuroinflammation. Yet medications and other therapeutic options to improve treatment are still very limited. Single-cell RNA sequencing (scRNA-seq), as a delightfully potent breakthrough technology, not only identifies various cell types and response states but also uncovers cell-specific gene expression changes, gene regulatory networks, intercellular communication, and cellular movement trajectories, among others, in different cell types. In this review, we describe the technology of scRNA-seq in detail and discuss and summarize the application of scRNA-seq in exploring neurological diseases, elaborating the corresponding specific mechanisms of the diseases as well as providing a reliable basis for new therapeutic approaches. Finally, we affirm that scRNA-seq promotes the development of the neuroscience field and enables us to have a deeper cellular understanding of neurological diseases in the future, which provides strong support for the treatment of neurological diseases and the improvement of patients' prognosis.

The prevalence and risk factors study of cognitive impairment: Analysis of the elderly population of Han nationality in Hunan province, China

OBJECTIVE

A large number of studies have found that the prevalence of cognitive impairment varies in different regions. However, data on cognitive impairment in the Chinese population is still lacking. The goal of this study was to assess the prevalence of cognitive impairment among the elderly in a region of China and explore the associated risk factors.

METHODS

We performed a population-based cross-sectional survey from April to June 2022. Residents come from three villages and six urban communities in the county-level city of Liuyang in southern China (N = 3233) and the coverage rate of our study population reached 73%. Participants were assessed with a series of clinical examinations and neuropsychological measures. A total of 2598 participants were selected after filtering out those under 60 years old or with incomplete data. Patients with cognitive impairment included those with mild cognitive impairment (MCI) or dementia who met standard diagnostic criteria.

RESULTS

The prevalence of cognitive impairment, MCI, and dementia among participants aged 60 years and older were 21.48% (95% CI, 19.90-23.10), 15.70% (95% CI, 14.30-17.10), and 5.77 (95% CI, 4.90-6.70), respectively. And residents in villagers were more likely to have cognitive impairment than in urban communities (p < 0.001). Age growth and education level were independent influencing factors for cognitive impairment in all populations (p < 0.001). For lifestyles factors, both smoking and drinking reduced the risk of cognitive impairment (p < 0.05), but when further quantified, the link disappeared. Moreover, having cerebrovascular disease and severe vision impairment were risk factors (p < 0.05).

CONCLUSION

A representative prevalence of cognitive impairment, MCI, and dementia was found in the elderly Han Chinese population in Southern China. And we further explored the role of known risk factors, particularly in physical activity, smoking, and alcohol consumption.

Dementia literacy and familiarity with term dementia: An exploratory study from a psychiatry outpatient setting

Objectives

Dementia, often misperceived as an inherent facet of aging, is, in fact, a progressive neurodegenerative condition. It carries a significant stigma due to its associated psychological and behavioral manifestations, leading to neglect and abuse within households. Studies reveal an alarming 90% treatment gap for dementia in India, largely due to limited knowledge about symptom recognition and accessing services. Thus, enhancing dementia literacy becomes crucial for early diagnosis and proper management. This study aims to assess dementia literacy and familiarity with the term "dementia" in a North Indian tertiary health-care setting.

Materials and Methods

This cross-sectional study used a case vignette method among patients and their attendants at psychiatry outpatient setting in a tertiary care hospital. A validated Hindi-translated case vignette depicting a dementia patient was employed. The study gathered sociodemographic data, the case vignette, and three related questions. Participants read the vignette and provided answers. The analysis included 200 responses collected in 1 month.

Results

Respondents predominantly associated the case's condition with memory issues, mental illness, and psychosocial factors. They suggested social support, a nurturing family environment, communal living, and consulting a doctor for the protagonist. Familiarity with "dementia" was at a mere 24%.

Conclusion

Dementia literacy and awareness of "dementia" are notably low in our sample. Urgent efforts are required to enhance dementia awareness to facilitate timely prevention, early detection, and effective management.

Socioeconomic status, lifestyle and risk of incident dementia: a prospective cohort study of 276730 participants

Healthy lifestyle might alleviate the socioeconomic inequities in health, but the extent of the joint and interactive effects of these two factors on dementia are unclear. This study aimed to detect the joint and interactive associations of socioeconomic status (SES) and lifestyle factors with incident dementia risk, and the underlying brain imaging alterations. Cox proportional hazards analysis was performed to test the joint and interactive associations. Partial correlation analysis was performed to reflect the brain imaging alterations. A total of 276,730 participants with a mean age of 55.9 (±8.0) years old from UK biobank were included. Over 8.5 (±2.6) years of follow-up, 3013 participants were diagnosed with dementia. Participants with high SES and most healthy lifestyle had a significantly lower risk of incident dementia (HR=0.19, 95% CI=0.14 to 0.26, P<2×10-16), Alzheimer's disease (AD, HR=0.19, 95% CI=0.13 to 0.29, P=8.94×10-15), and vascular dementia (HR=0.24, 95% CI=0.12 to 0.48, P=7.57×10-05) compared with participants with low SES and an unhealthy lifestyle. Significant interactions were found between SES and lifestyle on dementia (P=0.002) and AD (P=0.001) risks; the association between lifestyle and dementia was stronger among those of high SES. The combination of high SES and healthy lifestyle was positively associated with higher volumes in brain regions vulnerable to dementia-related atrophy. These findings suggest that SES and lifestyle significantly interact and influence dementia with its related brain structure phenotypes.

Relationship between Pain and Dementia: The Mediating Effect of Depression among Chinese Elderly

BACKGROUND

Chronic pain poses a significant problem for older adults and may potentially impact cognitive function. This study aimed to examine the cross-sectional relationship between pain severity and cognitive function in elderly individuals residing in the community. Additionally, this study sought to examine the mediating effect of depression on the relationship between pain and dementia.

METHODS

The study sample was derived from the 2018 China Health and Aging Longitudinal Study (CHARLS), comprising cross-sectional data from 4559 community residents aged 65 years or older. The primary outcome assessed was the occurrence of dementia, while the main independent variable was pain severity (none, little, somewhat, quite a bit, very). Depression score served as the mediating factor. Chi-square and binary logistic regression analyses were performed to examine the relationship between depression and the occurrence of pain and dementia. An intermediate model was constructed by stepwise regression.

RESULTS

The study indicates a significant association between cognitive impairment and both chronic pain and depressive symptoms in older adults living in China. Individuals who frequently report experiencing pain exhibit a higher likelihood of developing dementia when compared to those who do not report any pain (odds ratio (OR) = 1.72, p < 0.001). Moreover, depressive symptoms significantly mediate the relationship between pain and dementia, with the mediating effect accounting for 65.25%.

CONCLUSIONS

Chronic pain not only directly impacts patients' cognitive function but also indirectly exacerbates cognitive impairment through depressive symptoms as a mediating variable. For elderly individuals experiencing depressive symptoms, it is important to provide appropriate psychological treatment in conjunction with pain management strategies.

Highly accurate blood test for Alzheimer's disease is similar or superior to clinical cerebrospinal fluid tests

With the emergence of Alzheimer's disease (AD) disease-modifying therapies, identifying patients who could benefit from these treatments becomes critical. In this study, we evaluated whether a precise blood test could perform as well as established cerebrospinal fluid (CSF) tests in detecting amyloid-β (Aβ) plaques and tau tangles. Plasma %p-tau217 (ratio of phosporylated-tau217 to non-phosphorylated tau) was analyzed by mass spectrometry in the Swedish BioFINDER-2 cohort (n = 1,422) and the US Charles F. and Joanne Knight Alzheimer Disease Research Center (Knight ADRC) cohort (n = 337). Matched CSF samples were analyzed with clinically used and FDA-approved automated immunoassays for Aβ42/40 and p-tau181/Aβ42. The primary and secondary outcomes were detection of brain Aβ or tau pathology, respectively, using positron emission tomography (PET) imaging as the reference standard. Main analyses were focused on individuals with cognitive impairment (mild cognitive impairment and mild dementia), which is the target population for available disease-modifying treatments. Plasma %p-tau217 was clinically equivalent to FDA-approved CSF tests in classifying Aβ PET status, with an area under the curve (AUC) for both between 0.95 and 0.97. Plasma %p-tau217 was generally superior to CSF tests in classification of tau-PET with AUCs of 0.95-0.98. In cognitively impaired subcohorts (BioFINDER-2: n = 720; Knight ADRC: n = 50), plasma %p-tau217 had an accuracy, a positive predictive value and a negative predictive value of 89-90% for Aβ PET and 87-88% for tau PET status, which was clinically equivalent to CSF tests, further improving to 95% using a two-cutoffs approach. Blood plasma %p-tau217 demonstrated performance that was clinically equivalent or superior to clinically used FDA-approved CSF tests in the detection of AD pathology. Use of high-performance blood tests in clinical practice can improve access to accurate AD diagnosis and AD-specific treatments.

Amyloid-β prediction machine learning model using source-based morphometry across neurocognitive disorders

Previous studies have developed and explored magnetic resonance imaging (MRI)-based machine learning models for predicting Alzheimer's disease (AD). However, limited research has focused on models incorporating diverse patient populations. This study aimed to build a clinically useful prediction model for amyloid-beta (Aβ) deposition using source-based morphometry, using a data-driven algorithm based on independent component analyses. Additionally, we assessed how the predictive accuracies varied with the feature combinations. Data from 118 participants clinically diagnosed with various conditions such as AD, mild cognitive impairment, frontotemporal lobar degeneration, corticobasal syndrome, progressive supranuclear palsy, and psychiatric disorders, as well as healthy controls were used for the development of the model. We used structural MR images, cognitive test results, and apolipoprotein E status for feature selection. Three-dimensional T1-weighted images were preprocessed into voxel-based gray matter images and then subjected to source-based morphometry. We used a support vector machine as a classifier. We applied SHapley Additive exPlanations, a game-theoretical approach, to ensure model accountability. The final model that was based on MR-images, cognitive test results, and apolipoprotein E status yielded 89.8% accuracy and a receiver operating characteristic curve of 0.888. The model based on MR-images alone showed 84.7% accuracy. Aβ-positivity was correctly detected in non-AD patients. One of the seven independent components derived from source-based morphometry was considered to represent an AD-related gray matter volume pattern and showed the strongest impact on the model output. Aβ-positivity across neurological and psychiatric disorders was predicted with moderate-to-high accuracy and was associated with a probable AD-related gray matter volume pattern. An MRI-based data-driven machine learning approach can be beneficial as a diagnostic aid.

Cognition is selectively impaired in males with spinal pain: A retrospective analysis of data from the Longitudinal Study of Ageing Danish Twins

Cognitive decline and spinal pain (back pain [BP] and neck pain [NP]) represent a major public health challenge, yet the potential relationship between them remains elusive. A retrospective analysis of the Longitudinal Study of Ageing Danish Twins was performed to determine any potential relationships between BP/NP and cognitive function adjusting for age, sex, educational and socioeconomic status. A total of 4731 adults (2788 females/1943 males) aged 78 ± 6 (SD) years were included in the analysis. We observed a 1-month prevalence of 25% with BP, 21% with NP and 11% for combined BP/NP. While there were no differences in cognition scores for males and females reporting combined BP/NP, compared to those without combined BP/NP (34.38 points [95% confidence interval (CI) = 31.88, 36.88] vs. 35.72 points [95% CI = 35.19, 36.26]; P = 0.180; and 35.72 points [95% CI = 35.19, 36.26] vs. 35.85 points [95% CI = 35.39, 36.31]; P = 0.327; for male and females, respectively), an adjusted analysis revealed that males with combined BP/NP presented with lower cognitive scores compared to males without combined BP/NP (81.26 points [95% CI = 73.80, 88.72] vs. 79.48 points [95% CI = 70.31, 88.66]; P = 0.043). The findings of this hypothesis-generating study may highlight a potential sex-specific association between spinal pain and later-life neurodegeneration.

The spatial distribution of coupling between tau and neurodegeneration in amyloid-β positive mild cognitive impairment

Synergies between amyloid-β (Aβ), tau, and neurodegeneration persist along the Alzheimer's disease (AD) continuum. This study aimed to evaluate the extent of spatial coupling between tau and neurodegeneration (atrophy) and its relation to Aβ positivity in mild cognitive impairment (MCI). Data from 409 participants were included (95 cognitively normal controls, 158 Aβ positive (Aβ+) MCI, and 156 Aβ negative (Aβ-) MCI). Florbetapir PET, Flortaucipir PET, and structural MRI were used as biomarkers for Aβ, tau and atrophy, respectively. Individual correlation matrices for tau load and atrophy were used to layer a multilayer network, with separate layers for tau and atrophy. A measure of coupling between corresponding regions of interest (ROIs) in the tau and atrophy layers was computed, as a function of Aβ positivity. Fewer than 25% of the ROIs across the brain showed heightened coupling between tau and atrophy in Aβ+ , relative to Aβ- MCI. Coupling strengths in the right rostral middle frontal and right paracentral gyri, in particular, mediated the association between Aβ burden and cognition in this sample.

Glycemic control and dementia risk in patients aged above and below 75 years

Background

There is a lack of data about the treatment effect of glycemic control on incident dementia in patients with advanced age.

Methods

In a nationwide Korean cohort of 79,076 diabetic patients 75 years or older and a representative cohort of 74,672 diabetics aged 50 to 74 years, multivariable-adjusted incidence of overt dementia was estimated across yearly-averaged on-treatment fasting blood glucose (FBG) levels.

Results

During 9-year follow-up, overt dementia was noted in 24,710 (31.2%) patients 75 years or older and in 5237 (7.0%) patients aged 50 to 74 years. For dementia risk, J-shaped associations were observed across on-treatment FBG levels (80-99, 100-109, 110-125, 126-139, 140-159, 160-179, and 180-900 mg/dl) in patients 75 years or older (respective incidence: 49.3, 45.7, 45.9, 45.7, 48.5, 51.5, and 57.9 per 1000 person-years) and in those aged 50 to 74 years (respective incidence: 8.9, 8.3, 7.7, 7.6, 8.0, 8.6, and 10.6 per 1000 person-years) with a significant interaction of FBG level and age group (P = 0.001). For all-cause mortality, the J-shaped association curve was left-shifted in patients 75 years or older (respective incidence: 64.9, 59.1, 57.6, 60.4, 64.0, 70.9, and 90.4 per 1000 person-years) relative to that in patients aged 50 to 74 years (respective incidence: 15.7, 13.4, 12.3, 12.2, 13.4, 15.7, and 21.8 per 1000 person-years; P < 0.001 for interaction).

Conclusion

The achieved glycemic level with the lowest risk for dementia and mortality was lower in older patients, and absolute risk increase related to poorly controlled glucose was greater in the elderly compared with younger patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13340-023-00684-4.

Biomarker-based staging of Alzheimer disease: rationale and clinical applications

Disease staging, whereby the spatial extent and load of brain pathology are used to estimate the severity of Alzheimer disease (AD), is pivotal to the gold-standard neuropathological diagnosis of AD. Current in vivo diagnostic frameworks for AD are based on abnormal concentrations of amyloid-β and tau in the cerebrospinal fluid or on PET scans, and breakthroughs in molecular imaging have opened up the possibility of in vivo staging of AD. Focusing on the key principles of disease staging shared across several areas of medicine, this Review highlights the potential for in vivo staging of AD to transform our understanding of preclinical AD, refine enrolment criteria for trials of disease-modifying therapies and aid clinical decision-making in the era of anti-amyloid therapeutics. We provide a state-of-the-art review of recent biomarker-based AD staging systems and highlight their contributions to the understanding of the natural history of AD. Furthermore, we outline hypothetical frameworks to stage AD severity using more accessible fluid biomarkers. In addition, by applying amyloid PET-based staging to recently published anti-amyloid therapeutic trials, we highlight how biomarker-based disease staging frameworks could illustrate the numerous pathological changes that have already taken place in individuals with mildly symptomatic AD. Finally, we discuss challenges related to the validation and standardization of disease staging and provide a forward-looking perspective on potential clinical applications.

Changing profiles of the burden of Alzheimer's disease and other dementias attributable to smoking in the belt and road initiative countries: A secondary analysis of global burden of disease 2019

Objectives

This study was aimed at analyzing the burden and trend of Alzheimer's disease and other dementias attributed to smoking (SADD) in the Belt and Road Initiative (BRI) countries during 1990-2019.

Methods

Data from The 2019 Global Burden of Disease Study was used to extract information on the burden of SADD in terms of the numbers and age-standardized rate of mortality (ASMR) and disability-adjusted life years (ASDALR) in the BRI countries for 1990-2019. The average annual percent change (AAPC) was used to analyze the temporal trends of ASDALR from 1990 to 2019 and in the final decade by Joinpoint regression analysis.

Results

The DALYs of SADD were the highest in China, India, and the Russian Federation in 1990 and in Lebanon, Montenegro and Bosnia, and Herzegovina in 2019. From 1990 to 2019, the ASDALR in China had increased from 55.50/105 to 66.18/105, but decreased from 2010 to 2019, while that of India had declined from 32.84/105 to 29.35/105, but increased from 2010 to 2019. The ASDALR showed the fastest increase in the Russian Federation, with AAPC of 1.97% (95% confidence interval [CI]: 1.77%, 2.16%), and the fastest decline in Sri Lanka, with AAPC of -2.69% (95% CI: 2.79%, -2.59%). ASMR and ASDALR from SADD showed a substantial decline during 1990-2019 both globally and in the different socio-demographic index (SDI) regions (all P < 0.05, except for the high-middle-SDI region). Compared to the rates in males, the AAPC in ASDALR of females was significantly greater in 20 countries(all P < 0.05). In the age group of 20-54 years, the DALYs rate showed a decreasing trend only in 13 members in the low-SDI region (all P < 0.05).

Conclusion

Under the premise of eliminating the differences, mobilizing resources in the country itself, the BRI organization, and globally will help reduce the global SADD burden and achieve healthy and sustainable development.

Mechanisms with network pharmacology approach of Ginsenosides in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by memory loss, cognitive disorder, language dysfunction, and mental disability. The main neuropathological changes in AD mainly include amyloid plaque deposition, neurofibrillary tangles, synapse loss, and neuron reduction. However, the current anti-AD drugs do not demonstrate a favorable effect in altering the pathological course of AD. Moreover, long-term use of these drugs is usually accompanied with various side effects. Ginsenosides are the major active constituents of ginseng and have protective effects on AD through various mechanisms in both in vivo and in vitro studies. In this review, we focused on discussing the therapeutic potential effects and the mechanisms of pharmacological activities of ginsenosides in AD, to provide new insight for further research and clinical application of ginsenosides in the future. Recent studies on the pharmacological effects and mechanisms of ginsenosides were retrieved from Chinese National Knowledge Infrastructure, National Science and Technology Library, Wanfang Data, Elsevier, ScienceDirect, PubMed, SpringerLink, and the Web of Science database up to April 2023 using relevant keywords. Network pharmacology and bioinformatics analysis were used to predict the therapeutic effects and mechanisms of ginsenosides against AD. Ginsenosides presented a wide range of therapeutic and biological activities, including alleviating Aβ deposition, decreasing tau hyperphosphorylation, regulating the cholinergic system, resisting oxidative stress, modulating Ca2+ homeostasis, as well as anti-inflammation and anti-apoptosis in neurons, respectively. For further developing the therapeutic potential as well as clinical applications, the network pharmacology approach was combined with a summary of published studies.

Resting heart rate and risk of dementia: a Mendelian randomization study in the international genomics of Alzheimer's Project and UK Biobank

Background

Observational studies have demonstrated that a higher resting heart rate (RHR) is associated with an increased risk of dementia. However, it is not clear whether the association is causal. This study aimed to determine the causal effects of higher genetically predicted RHR on the risk of dementia.

Methods

We performed a two-sample Mendelian randomization analysis to investigate the causal effect of higher genetically predicted RHR on Alzheimer's disease (AD) using summary statistics from genome-wide association studies. The generalized summary Mendelian randomization (GSMR) analysis was used to analyze the corresponding effects of RHR on following different outcomes: 1) diagnosis of AD (International Genomics of Alzheimer's Project), 2) family history (maternal and paternal) of AD from UK Biobank, 3) combined meta-analysis including these three GWAS results. Further analyses were conducted to determine the possibility of reverse causal association by adjusting for RHR modifying medication.

Results

The results of GSMR showed no significant causal effect of higher genetically predicted RHR on the risk of AD (βGSMR = 0.12, P = 0.30). GSMR applied to the maternal family history of AD (βGSMR = -0.18, P = 0.13) and to the paternal family history of AD (βGSMR = -0.14, P = 0.39) showed the same results. Furthermore, the results were robust after adjusting for RHR modifying drugs (βGSMR = -0.03, P = 0.72).

Conclusion

Our study did not find any evidence that supports a causal effect of RHR on dementia. Previous observational associations between RHR and dementia are likely attributed to the correlation between RHR and other cardiovascular diseases.

Quality of life of family carers of people living with dementia: review of systematic reviews of observational and intervention studies

INTRODUCTION

Family members are the primary source of support for the growing number of people living with dementia (PLWD) worldwide. However, caring for a person living with dementia can have detrimental impacts on the carer quality of life (QoL). This review of systematic reviews explored the factors associated with the QoL of family carers of PLWD and interventions aimed at improving their QoL.

SOURCES OF DATA

Several health-related databases (PUBMED, Psychinfo, Google Scholar and COCHRANE) were consulted in November 2022. Nineteen systematic reviews were included, and their methodological quality was assessed via AMSTAR-2.

AREAS OF AGREEMENT

Better carer physical and mental health, provision of formal support, relationship quality between carers and PLWD, as well as positive psychological traits were associated with better carer QoL. There is no one-size-fits-all intervention that can improve the QoL of all carers, but promising results were found in most of the interventions.

AREAS OF CONTROVERSY

There is inconsistency in evidence on the association between the carer age and QoL. The use of a wide range of QoL measures, particularly generic QoL scales, has contributed to inconsistencies when comparing the efficacy of interventions.

GROWING POINTS

Evidence suggests the need for a person-centred approach to improving carer QoL, considering individual and contextual needs as well as the continuum and progressive nature of dementia care.

TIMELY AREAS FOR DEVELOPING RESEARCH

Future research should be focused on understanding how to best implement and measure person-centred care approaches to carer QoL, including cost-effectiveness. More qualitative studies are necessary to explore carer negative and positive experiences of QoL.

Sleep features and long-term incident neurodegeneration: a polysomnographic study

STUDY OBJECTIVES

Sleep is altered early in neurodegenerative diseases (NDDs) and may contribute to neurodegeneration. Long-term, large sample-size studies assessing NDDs association with objective sleep measures are scant. We aimed to investigate whether video-polysomnography (v-PSG)-based sleep features are associated with long-term NDDs incidence.

METHODS

Retrospective cohort study of patients referred 2004-2007 to the Sleep Disorders Unit, Neurology, Medical University Innsbruck, Austria. All patients ≥ 18 years undergoing v-PSG and without NDDs at baseline or within 5 years were included. Main outcome was NDDs diagnosis ≥5 years after v-PSG.

RESULTS

Of 1454 patients assessed for eligibility, 999 (68.7%) met inclusion criteria (68.3% men; median age 54.9 (IQR 33.9-62.7) years). Seventy-five patients (7.5%) developed NDDs and 924 (92.5%) remained disease-free after a median of 12.8 (IQR 9.9-14.6) years. After adjusting for demographic, sleep, and clinical covariates, a one-percentage decrease in sleep efficiency, N3-, or rapid-eye-movement (REM)-sleep was associated with 1.9%, 6.5%, or 5.2% increased risk of incident NDDs (HR 1.019, 1.065, and 1.052). One-percentage decrease in wake within sleep period time represented a 2.2% reduced risk of incident NDDs (HR 0.978). Random-forest analysis identified wake, followed by N3 and REM-sleep percentages, as the most important feature associated with NDDs diagnosis. Additionally, multiple sleep features combination improved discrimination of incident NDDs compared to individual sleep stages (concordance-index 0.72).

CONCLUSIONS

These findings support contribution of sleep changes to NDDs pathogenesis and provide insights into the temporal window during which these differences are detectable, pointing to sleep as early NDDs marker and potential target of neuroprotective strategies.

Dementia prevalence among hospitalized older patients: a multicenter study in Iran

Dementia poses a significant societal and health challenge in the 21st century, with many hospitalized patients experiencing dementia without a documented diagnosis.

Objective

To evaluate the prevalence of dementia and its associated risk factors among older patients admitted to hospitals.

Methods

The study included older patients (≥ 60 years) admitted to medical departments of a general hospital in three major Iranian cities. Researchers utilized the Activities of Daily Living-Instrumental Activities of Daily Living (ADL-IADL) scale, the Geriatric Depression Scale (GDS), the Mini-Cog test, the 4 A's test (4AT), and the Abbreviated Mental Test Score (AMTS). Among the 420 recruited older inpatients, 228 (54.3%) were female.

Results

The mean age of participants was 71.39 years (standard deviation ±7.95), with 30.7% diagnosed with major neurocognitive disorder (dementia). The likelihood of dementia exhibited statistically significant correlations with gender, age, number of children, and occupation.

Conclusions

Screening older individuals for cognitive impairment upon hospital admission holds the potential to prevent adverse outcomes and enhance the quality of treatment for patients concurrently dealing with dementia.

Logotherapy-Based Interventions for Chinese Family Caregivers of Older Adults with Dementia Through Online Groups: A Mixed-Methods Study

Chinese family caregivers of people with dementia (PWD) can suffer from physical and psychological burden. This study aimed to examine the effects of logotherapy-based interventions on Chinese family caregivers of older adults with dementia to decrease caregiver burden. This mixed-methods study used a pre-experimental design with pre-posttests and semi-structured interviews. A purposive sample of 13 family caregivers from a suburban district in Shanghai was enrolled with (1) caregiver burden and (2) access and capability to use smart devices. Participants received eight online group logotherapy sessions with a focus on hope and meaning construction. Participants completed the Zarit Burden Interview, a 22-item measure of caregiver burden, before and after the intervention, and a 30-min semi-structured interview post-intervention. From the quantitative data, dementia caregivers reported severe caregiving burdens at the baseline (M = 54.77, SD = 9.33). Caregiver burden significantly decreased after the logotherapy-based intervention (M = 52.15, SD = 8.80, p < .001). Two themes pertaining to participants' experiences in intervention emerged from the qualitative data: (1) improved attitudes toward suffering, and (2) enhanced sense of meaning in life and hope. The cultural relevance of logotherapy to Chinese familism and Confucianism may further enhance its feasibility in the Chinese context.

Accelerating P300-based neurofeedback training for attention enhancement using iterative learning control: a randomised controlled trial

Objective. Neurofeedback (NFB) training through brain-computer interfacing has demonstrated efficacy in treating neurological deficits and diseases, and enhancing cognitive abilities in healthy individuals. It was previously shown that event-related potential (ERP)-based NFB training using a P300 speller can improve attention in healthy adults by incrementally increasing the difficulty of the spelling task. This study aims to assess the impact of task difficulty adaptation on ERP-based attention training in healthy adults. To achieve this, we introduce a novel adaptation employing iterative learning control (ILC) and compare it against an existing method and a control group with random task difficulty variation.Approach. The study involved 45 healthy participants in a single-blind, three-arm randomised controlled trial. Each group underwent one NFB training session, using different methods to adapt task difficulty in a P300 spelling task: two groups with personalised difficulty adjustments (our proposed ILC and an existing approach) and one group with random difficulty. Cognitive performance was evaluated before and after the training session using a visual spatial attention task and we gathered participant feedback through questionnaires.Main results. All groups demonstrated a significant performance improvement in the spatial attention task post-training, with an average increase of 12.63%. Notably, the group using the proposed iterative learning controller achieved a 22% increase in P300 amplitude during training and a 17% reduction in post-training alpha power, all while significantly accelerating the training process compared to other groups.Significance. Our results suggest that ERP-based NFB training using a P300 speller effectively enhances attention in healthy adults, with significant improvements observed after a single session. Personalised task difficulty adaptation using ILC not only accelerates the training but also enhances ERPs during the training. Accelerating NFB training, while maintaining its effectiveness, is vital for its acceptability by both end-users and clinicians.

Toxoplasma gondii seropositivity and cognitive functioning in older adults: an analysis of cross-sectional data of the National Health and Nutrition Examination Survey 2011-2014

OBJECTIVES

This study sought to examine the relationship between Toxoplasma gondii seropositivity and cognitive function in older adults.

DESIGN

An observational cross-sectional study.

SETTING

The National Health and Nutrition Examination Survey (NHANES) study took place at participants' homes and mobile examination centres.

PARTICIPANTS

A total of 2956 older adults aged 60 and above from the NHANES from 2011 to 2014 were included in the study. Exposure of interest: participants had serum Toxoplasma gondii antibody analysed in the laboratory. A value>33 IU/mL was categorised as seropositive for Toxoplasma gondii infection; <27 IU/mL was categorised as seronegative for Toxoplasma gondii infection.

PRIMARY AND SECONDARY OUTCOME MEASURES

Cognitive tests included the Consortium to Establish a Registry for Alzheimer's Disease Word Learning subtest (CERAD-WL) for immediate and delayed memory, the Animal Fluency Test (AFT), and the Digit Symbol Substitution Test (DSST).

RESULTS

About half of the 2956 participants (mean age 70.0) were female (51.0%), non-Hispanic White (48.3%), and completed some college or above (48.3%). A total of 703 participants were positive for Toxoplasma gondii infection (23.8%). Adjusted linear regression showed that compared with participants with negative Toxoplasma gondii infection, those with positive Toxoplasma gondii infection had lower CERAD-WL immediate memory (beta (β) -0.16, 95% CI -0.25 to -0.07), CERAD-WL delayed memory (β -0.15, 95% CI -0.24 to -0.06), AFT (β -0.15, 95% CI -0.24 to -0.06), DSST (β -0.34, 95% CI -0.43 to -0.26), and global cognition (β -0.24, 95% CI -0.32 to -0.16) z-scores after controlling for the covariates.

CONCLUSIONS

Toxoplasma gondii seropositivity is associated with worse immediate and delayed verbal learning, language proficiency, executive functioning, processing speed, sustained attention, working memory, as well as global cognition in older adults. Public health measures aiming at preventing Toxoplasma gondii infection may help preserve cognitive functioning in older adults.

A causal relationship between panic disorder and risk of alzheimer disease: a two-sample mendelian randomization analysis

BACKGROUND

Observational studies have suggested a link between panic disorder (PD) and Alzheimer disease (AD). This study aimed to identify the underlying association of PD with the risk of AD using Mendelian randomization.

METHODS

Genetic instrumental variables (IVs) were retrieved in the genome-wide association study between PD and AD. Then, five different models, namely inverse variance weighting (IVW), weighted median, weighted mode, MR-Egger and MR-robust adjusted profile scores (MR-RAPS), were used for MR Analysis. Finally, the heterogeneity and pleiotropy of identified IVs were verified by multiple sensitivity tests.

RESULTS

The Cochran's Q test based on MR Egger and IVW showed that no evidence of heterogeneity was found in the effects of instrumental variables, so a fixed-effect model was used. IVW analysis (OR 1.000479, 95% CI [1.000147056, 1.000811539], p = 0.005) indicated that PD was associated with an increased risk of AD, and a causal association existed between them. Meanwhile, weighted median (OR 1.000513373, 95% CI [1.000052145, 1.000974814], p = 0.029) and MR-RAPS (OR 1.000510118, 95% CI [1.000148046, 1.00087232], p = 0.006) also showed the similar findings. In addition, extensive sensitivity analyses confirmed the robustness and accuracy of these results.

CONCLUSION

This investigation provides evidence of a potential causal relationship between PD and the increased risk of AD. Based on our MR results, when diagnosing and treating patients with PD, clinicians should pay more attention to their AD-related symptoms to choose therapeutic measures or minimize comorbidities. Furthermore, the development of drugs that improve both PD and AD may better treat patients with these comorbidities.

Association of periodontal disease treatment with mortality in patients with dementia: a population-based retrospective cohort study (2002-2018)

Dementia is one of the leading causes of death worldwide. In this study, we analyzed the association of periodontal treatment with the risk of death in patients with dementia. The analyzed data were obtained by linking the National Health Insurance Corporation claims data between 2002 and 2018 to the Statistics Korea death registry. In total, 1,131,406 patients with dementia aged ≥ 65 years had undergone dental treatment during the study period. Time-dependent Cox proportional hazards model was performed. The mortality rate was approximately 10% among the patients with dementia. The 17-years cumulative survival rates for patients who received periodontal treatment and their untreated counterparts were 83.5% and 71.5%, respectively. The crude hazard ratio of the periodontal group was approximately twice as high as that of the non-periodontal group (1.99; P < 0.001). Furthermore, in the regression model that was adjusted for socio-demographic variables and systematic chronic diseases, the risk of death in the non-periodontal group was approximately 1.83 times higher than that of the periodontal group (P < 0.00). These findings suggest that preventive periodontal treatment may decrease mortality risk in older people with dementia.

Prospective cohort study evaluating the association between influenza vaccination and neurodegenerative diseases

The effect of influenza vaccination (FluVac) on the risk of neurodegenerative diseases has not been well evaluated in prospective populations. We aimed to assess the association between FluVac and the risk of dementia and Parkinson's disease (PD) in people aged 60 years or older through a prospective population-based cohort from the UK Biobank. A time-varying Cox regression model adjusted for baseline and repeatedly measured covariates was used to estimate the hazard ratio (HR) and 95% confidence interval (CI) of the association between influenza vaccination and risk of dementia/PD. We took into account 70,938 participants in the cohort, including 38,328 participants who got vaccinated. During a median follow-up period of 12.2 years, 2087 incident dementia cases occurred, including 281 cases who received FluVac and 1806 cases who were not vaccinated. In addition, 742 incident PD cases occurred, among whom 131 cases received FluVac and 611 PD cases did not receive FluVac. FluVac was associated with reduced dementia risk with an HR of 0.83 (95% CI, 0.72-0.95) but was not associated with PD incidence (HR = 1.07; 95% CI, 0.87-1.32) after controlling baseline and repeatedly measured covariates. Further, among all dementia cases, there were 733 Alzheimer's disease (AD) (94 vaccinated cases and 639 non-vaccinated cases), 307 vascular dementia (VD) (34 vaccinated cases and 273 non-vaccinated cases), and 1047 cases with other dementias (OD) (153 vaccinated cases and 894 non-vaccinated cases). The HRs for the associations between FluVac and AD, VD, and OD were 0.79 (95% CI, 0.63-1.00), 0.58 (95% CI, 0.39-0.86), and 0.94 (95% CI, 0.78-1.14) respectively. A dose-response relationship was found in the association between FluVac and dementia but not in the association with PD. A major limitation of the study is the low accuracy in the diagnosis of dementia subtypes, namely AD, VD, and OD. However, Results of sensitivity analyses were consistent with the primary analyses. In conclusion, influenza vaccination is significantly associated with a reduced risk of incident dementia but not PD in community-dwelling adults in the UK Biobank population.

Periodontitis and brain magnetic resonance imaging markers of Alzheimer's disease and cognitive aging

INTRODUCTION

We examined the association of clinical, microbiological, and host response features of periodontitis with MRI markers of atrophy/cerebrovascular disease in the Washington Heights Inwood Columbia Aging Project (WHICAP) Ancillary Study of Oral Health.

METHODS

We analyzed 468 participants with clinical periodontal data, microbial plaque and serum samples, and brain MRIs. We tested the association of periodontitis features with MRI features, after adjusting for multiple risk factors for Alzheimer's disease/Alzheimer's disease-related dementia (AD/ADRD).

RESULTS

In fully adjusted models, having more teeth was associated with lower odds for infarcts, lower white matter hyperintensity (WMH) volume, higher entorhinal cortex volume, and higher cortical thickness. Higher extent of periodontitis was associated with lower entorhinal cortex volume and lower cortical thickness. Differential associations emerged between colonization by specific bacteria/serum antibacterial IgG responses and MRI outcomes.

DISCUSSION

In an elderly cohort, clinical, microbiological, and serological features of periodontitis were associated with MRI findings related to ADRD risk. Further investigation of causal associations is warranted.

Variability in Alzheimer's disease mortality from European vital statistics, 2012-2020

OBJECTIVE

Data regarding the trends in Alzheimer's disease (AD) mortality in the modern European Union (EU-27) member states are lacking. We assess the sex- and age-specific trends in AD mortality in the EU-27 member states between years 2012 and 2020.

METHODS

Data on cause-specific deaths and population numbers by sex for each country of the EU-27 were retrieved through publicly available European Statistical Office (EUROSTAT) dataset from 2012 to 2020. AD-related deaths were ascertained when the ICD-10 code G30 was listed as the primary cause of death in the medical death certificate. To calculate annual trends, we assessed the average annual percent change (AAPC) with relative 95% confidence intervals (CIs) using Joinpoint regression.

RESULTS

During the study period, 751,493 deaths (1.7%, 233,271 males and 518,222 females) occurred in the EU-27 because of AD. Trends in the proportion of AD-related deaths per 1000 total deaths slightly increased from 16.8% to 17.5% (p for trend <0.001). The age-adjusted mortality rate was higher in women over the entire study period. Joinpoint regression analysis revealed a stagnation in age-adjusted AD-related mortality from 2012 to 2020 among EU-27 Member States (AAMR: -0.1% [95% CI: -1.8-1.79], p = 0.94). Stratification by Country showed relevant regional disparities, especially in the Northern and Eastern EU-27 member states.

CONCLUSIONS

Over the last decade, the age-adjusted AD-related mortality rate has plateaued in EU-27. Important disparities still exist between Western and Eastern European countries.

In silico and in vitro analyses of a novel FoxO1 agonist reducing Aβ levels via downregulation of BACE1

AIMS

FoxO1 is an important target in the treatment of Alzheimer's disease (AD). However, FoxO1-specific agonists and their effects on AD have not yet been reported. This study aimed to identify small molecules that upregulate the activity of FoxO1 to attenuate the symptoms of AD.

METHODS

FoxO1 agonists were identified by in silico screening and molecular dynamics simulation. Western blotting and reverse transcription-quantitative polymerase chain reaction assays were used to assess protein and gene expression levels of P21, BIM, and PPARγ downstream of FoxO1 in SH-SY5Y cells, respectively. Western blotting and enzyme-linked immunoassays were performed to explore the effect of FoxO1 agonists on APP metabolism.

RESULTS

N-(3-methylisothiazol-5-yl)-2-(2-oxobenzo[d]oxazol-3(2H)-yl) acetamide (compound D) had the highest affinity for FoxO1. Compound D activated FoxO1 and regulated the expression of its downstream target genes, P21, BIM, and PPARγ. In SH-SY5Y cells treated with compound D, BACE1 expression levels were downregulated, and the levels of Aβ1-40 and Aβ1-42 were also reduced.

CONCLUSIONS

We present a novel small-molecule FoxO1 agonist with good anti-AD effects. This study highlights a promising strategy for new drug discovery for AD.

An Early and Unequal Decline: Life Course Trajectories of Cognitive Aging in the United States

Objectives: Cognitive aging is a lifelong process with implications for Alzheimer's disease and dementia. This study aims to fill major gaps in research on the natural history of and social disparities in aging-related cognitive decline over the life span. Methods: We conducted integrative data analysis of four large U.S. population-based longitudinal studies of individuals aged 12 to 105 followed over two decades and modeled age trajectories of cognitive function in multiple domains. Results: We found evidence for the onset of cognitive decline in the 4th decade of life, varying gender differences with age, and persistent disadvantage among non-Hispanic Blacks, Hispanics, and those without college education. We further found improvement in cognitive function across 20th century birth cohorts but widening social inequalities in more recent cohorts. Discussion: These findings advance an understanding of early life origins of dementia risk and invite future research on strategies for promoting cognitive health for all Americans.

Relationship between mortality and vitality in patients with mild cognitive impairment/dementia: An 8-year retrospective study

AIM

The study aimed to investigate the association of vitality, as measured using the vitality index (Vix), with the survival outcomes of older adults with mild cognitive impairment (MCI) or dementia.

METHODS

We analyzed data from 3731 patients in the National Center for Geriatrics and Gerontology - Life Stories of Individuals with Dementia cohort from July 2010 to September 2018. The main focus was to correlate Vix scores with the time from the initial visit to death. Vix was categorized into "moderately to severely impaired" (0-7 points), "mildly impaired" (8-9 points), and "normal" (10 points) groups. Survival outcomes were assessed using a Cox proportional hazards model, adjusted for various factors. We conducted a mediation analysis to evaluate the effect of body mass index (BMI), instrumental activities of daily living (IADL), and basic activities of daily living (BADL) on the association between vitality and mortality. Stratified analysis was also conducted for the Mini-Mental State Examination groups.

RESULTS

We included 2740 patients with an average follow-up of 1315 days. The mortality rate was 15.7%. The Vix distribution was 16% at 0-7 points; 40%, 8-9 points; and 44%, 10 points. Patients in the "moderately to severely impaired" category, characterized by lower Vix scores, exhibited notably higher mortality rates. Mediation effects emphasized the significant roles of BMI, IADL, and BADL in influencing survival outcomes.

CONCLUSIONS

Vitality significantly influences patient survival rates. The association between vitality and mortality seems to be mediated by IADL and BADL, which has significant clinical implications. Geriatr Gerontol Int 2024; 24: 221-228.

The prevalence of mild cognitive impairment and dementia among rural dwellers: A systematic review and meta-analysis

The mild cognitive impairment (MCI) and dementia in rural areas are increasingly attracting public attention. However, their prevalence is still unclear. This study aims to reveal the distribution of MCI and dementia in rural areas. We systematically searched PubMed, Web of Science, Embase, and PsycINFO up to June 2023 for cohort and cross-sectional studies. Meta-analysis was conducted using random-effects models to evaluate the prevalence of MCI and dementia. Thirty-five studies with 16,936 participants met the inclusion criteria. The pooled prevalence of MCI and dementia was 27 % (n = 12, 95 %CI = 0.21-0.32, I2 = 99.5 %, P < 0.001) and 7 % (n = 27, 95 %CI = 0.05-0.08, I2 = 99.30 %, P < 0.001), respectively. Subgroup analyses revealed that aged 60 years or older [(MCI: 29 %, 95 %CI = 0.20-0.38, I2 = 99.7 %, P < 0.001), (dementia: 9 % (95 %CI = 0.06-0.12, I2 = 99 %, P < 0.001)], female [(MCI: 29 %, 95 %CI = 0.19-0.40, I2 = 99.3 %, P < 0.001), (dementia: 7 %, 95 % CI = 0.04-0.12, I2 = 98.66 %, P < 0.001)], a-MCI (19 %, 95 %CI = 0.12-0.26, I2 = 97.62 %, P < 0.001) and AD (4 %, 95 %CI = 0.02-0.05, I2 = 98.60 %, P < 0.001) showed higher prevalence. The prevalence of MCI and dementia in rural China was 23 % (95 %CI = 0.18-0.29, I2 = 99.5 %, P < 0.001) and 6 % (95 %CI = 0.04-0.08, I2 = 99.6 %, P < 0.001), respectively. Implementing cognitive impairment screening and intervention measures is necessary to improve the cognitive function of the rural population.

Comorbidity and household income as mediators of gender inequalities in dementia risk: a real-world data population study

BACKGROUND

Low household income (HI), comorbidities and female sex are associated with an increased risk of dementia. The aim of this study was to measure the mediating effect of comorbidity and HI on the excess risk due to gender in relation to the incidence and prevalence of dementia in the general population.

METHODS

A retrospective and observational study using real-world data analysed all people over 60 who were registered with the Basque Health Service in Gipuzkoa. The study measured HI level, the Charlson comorbidity index (CCI), age and sex. The prevalence and incidence of dementia were analysed using logistic regression and Poisson regression models, respectively, adjusted by HI, sex, comorbidity and age. We estimated the combined mediation effect of HI and comorbidity on the prevalence of dementia associated with gender.

RESULTS

Of the 221,777 individuals, 3.85% (8,549) had a diagnosis of dementia as of 31 December 2021. Classification by the CCI showed a gradient with 2.90% in CCI 0-1, 10.60% in CCI 2-3 and 18.01% in CCI > 3. Both low HI and gender were associated with a higher crude prevalence of dementia. However, in the CCI-adjusted model, women had an increased risk of dementia, while HI was no longer statistically significant. The incidence analysis produced similar results, although HI was not significant in any model. The CCI was significantly higher for men and for people with low HI. The mediation was statistically significant, and the CCI and HI explained 79% of the gender effect.

CONCLUSIONS

Comorbidity and low HI act as mediators in the increased risk of dementia associated with female sex. Given the difference in the prevalence of comorbidities by HI, individual interventions to control comorbidities could not only prevent dementia but also reduce inequalities, as the risk is greater in the most disadvantaged population.