Association of plasma high-density lipoprotein cholesterol level with risk of incident dementia: a cohort study of healthy older adults

Association between abdominal obesity and cognitive decline among Chinese middle-aged and older adults: a 10-year follow-up from CHARLS

Introduction

The relationship between abdominal obesity and cognitive decline has controversial results, and the mediating effect of high-density lipoprotein cholesterol (HDL-C) between them remains uncertain. This study aims to explore the association between abdominal obesity and cognitive decline in middle-aged and older adults, including dose-response relationship and age differences, as well as the mediating effect of HDL-C.

Methods

Data were obtained from the China Health and Retirement Longitudinal Study (CHARLS), involving 3,807 participants aged 45 and above from 2010 to 2020. The TICS-10 was used to assess cognitive function, and the group-based trajectory model (GBTM) was used to explore the potential heterogeneity of cognitive changes. Abdominal obesity was measured by baseline waist circumference (WC) and a sequentially adjusted unordered multinomial logistic regression was used to investigate the association between abdominal obesity and cognitive decline in middle-aged and older adults. Restricted cubic spline (RCS) model was adopted to analyze the dose-response relationship between WC and risk of cognitive decline. HDL-C was used as a mediator to examine the potential causal chain between abdominal obesity and cognitive decline.

Results

Among the 3,807 participants, a total of 1,631 individuals (42.84%) had abdominal obesity. The GBTM identified 3 cognitive function trajectories: rapid decline (11.0%), slow decline (41.1%) and stable groups (47.9%). After controlling for confounders, participants with abdominal obesity were less likely to experience rapid decline (OR: 0.67, 95%CI: 0.51-0.8) and slow decline (OR: 0.81, 95%CI: 0.69-0.95) of cognitive function, compared to those with normal WC. RCS analysis showed a decreased risk of cognitive decline with increasing WC. In the age subgroup analysis, the protective effect was significant only in the population aged 50 and above. HDL-C mediated 19.15% (P < 0.05) of the relationship between abdominal obesity and cognitive decline.

Conclusion

Abdominal obesity had a significant protective effect on cognitive decline in Chinese middle-aged and older adults, with HDL-C playing a mediating role in the relationship between abdominal obesity and cognitive decline.

Longitudinal Association of Remnant Cholesterol With Cognitive Decline Varies by Lipid-Lowering Drugs: A Population-Based Cohort Study

BACKGROUND

Although the association between remnant cholesterol (RC) and cognitive impairment has been reported, the association of RC with cognitive decline remains scarce. Also, the role of lipid-lowering therapy in the association is unclear. The study aimed to examine the longitudinal associations of RC with cognitive decline by lipid-lowering drug use during follow-up.

METHODS AND RESULTS

The study used data from Wave 2 (2004-2005) to Wave 8 (2016-2017) of the ELSA (English Longitudinal Study of Ageing). Global cognitive functions at baseline (Wave 2) and during the follow-up (Waves 3-8) were assessed by integrating 3 cognitive domains: memory capacity, semantic fluency, and orientation. Multivariate-adjusted linear mixed models were employed to examine the longitudinal associations, with results presented as β (95% CI) in SD/year. Of the 5053 participants ultimately included, 55.4% were female and the mean age (SD) was 65.7 (9.3) years. Per 1 mmol/L increment in RC was significantly associated with a faster rate of cognitive decline (β=-0.010 SD/year [95% CI -0.019 to -0.001]). Furthermore, we observed that association pattern between RC and cognitive decline only in the non-lipid-lowering drug group (β=-0.019 SD/year [95% CI, -0.031 to -0.007]) but not in the lipid-lowering drug group (β=0.007 SD/year [95% CI, -0.006 to 0.020]), with a significant interaction (P=0.015). Similar findings were observed for the 3 cognitive domains.

CONCLUSIONS

Higher baseline RC levels were associated with steeper cognitive decline. The use of lipid-lowering drugs might mitigate this decline. These findings underscore the importance of early RC monitoring and proactive management with lipid-lowering drugs in clinical practice.

Age-related hearing loss associated with cognitive impairment in the Polish cohort of the PURE study

Background

Currently, dementia is estimated to be the seventh most common cause of death and one of the leading causes of disability and dependency among older people worldwide. The main aim of this study is to analyze the association of presbycusis and cognitive impairment in the study population. Secondary aim is to identify the risk and prevalence of presbycusis taking into account bio- socio-demographic factors among the residents of Wrocław and surrounding villages.

Methods

Data from 891 participants (559 women and 332 men; mean age: 60.7 years; range: 39-81) in the Polish cohort of the PURE study who met the inclusion criteria for the PURE MIND sub-study and who had a cognitive and functional assessment completed (MoCA test, DSST test, TMT parts A and B, CES-D, SAGE test).

Results

Hearing loss was a significant risk factor for cognitive impairment as assessed using the MoCA, DSST, TMT A and TMT B tests. Mild cognitive impairment (MoCA < 26 score) was present in nearly half of those with hearing loss compared to 26.0 per cent of those without hearing loss (p = 0.036). Hearing loss increased the chance of MCI almost 1.5-fold [OR 1.34; CI 0.93-1.93]. Multivariate regression analysis showed that those with hearing loss, hypertension and diabetes scored significantly lower (worse) on the MoCA test (by -0.52 points [95% CI -0.99 to -0.06]; -0.48 points [95% CI -0.96 to -0.01] and -0.69 points [95% CI -1.16 to 0.23], respectively). Excessive body weight and diabetes increased the chance of developing hearing loss by more than 1.5-fold [OR 1.64; CI 1.03-2.68; OR 1.59; CI 1.04-2.41, respectively]. Hearing loss was significantly more common among men (22.3%), irrespective of level of education. The MCI was more common among rural residents (54.8% vs. 34.8%) and in participants with lower levels of education.

Conclusion

Age-related hearing loss is a modifiable risk factor for dementia, emphasizing the importance of routine hearing assessments and timely interventions. Integrating hearing loss management with strategies targeting vascular and metabolic health can help mitigate cognitive decline.

Triglycerides, high-density lipoprotein and cognitive function in middle-aged and older adults: a cross-sectional analysis

As China's population continues to age, addressing cognitive decline related to aging has become increasingly important. Simultaneously, rapid economic development has led to rising concerns about lipid metabolism disorders, particularly those involving blood lipids. Identifying modifiable risk factors early is critical to enhancing cognitive function in older adults. Thus, this study focuses on the relationship between triglycerides (TG), high-density lipoprotein (HDL), and cognitive performance to investigate potential mechanisms. A cross-sectional study was conducted using data from the 2015 China Health and Retirement Longitudinal Study (CHARLS) survey. Cognitive function was assessed across three domains: global cognition, episodic memory, and mental status. Fasting blood samples were analyzed for triglycerides and high-density lipoprotein (HDL) levels. The relationship between triglycerides, HDL, and cognitive function was examined using restricted cubic spline (RCS) analysis, multivariate linear regression, and mediation analysis. The analysis identifies a non-linear, inverse U-shaped relationship between triglycerides and both global cognition and episodic memory, with significant inflection points at a triglyceride (TG) level of 202.65 for global cognition and 115.04 for episodic memory. No non-linear relationship was observed between High-Density Lipoprotein (HDL) and cognitive outcomes, including global cognition, episodic memory, or mental status (p > 0.05). Linear mixed models indicate that HDL has a positive association with episodic memory, as shown by HDLQ1 (B = 0.0033, 95% CI: 0, 0.569), HDLQ2 (B = 0.039, 95% CI: 0.051, 0.594), and HDLQ3 (B = 0.033, 95% CI: 0.004, 0.556) compared to HDLQ4. A combined analysis of TG and HDL on episodic memory further demonstrated that the ''High-TG-low-HDL'' group (B = 0.036, 95% CI: 0.043, 0.578) had a significantly positive effect compared to the "High-HDL-low-TG" group. Mediation analysis revealed that Body Mass Index (BMI) indirectly mediated the HDL-episodic memory relationship, with a mediation effect size of 22.2%. In conclusion, this study explored the interplay between triglyceride levels, high-density lipoprotein cholesterol (HDL-C) levels, and cognitive function among middle-aged and elderly individuals in China. The findings reveal a U-shaped inverse relationship between triglyceride concentrations and cognitive ability, underscoring the need to maintain optimal triglyceride levels for cognitive health. Additionally, lower HDL levels (HDLQ1-Q3) were found to positively affect cognitive function, particularly in overall cognition and episodic memory, compared to higher HDL levels (HDLQ4). Importantly, body mass index (BMI) mediated the influence of HDL on episodic memory, with an effect size of 22.2%.

The nonlinear association of ratio of total cholesterol to high density lipoprotein with cognition ability: evidence from a community cohort in China

Background

Cholesterol is a critical component of the human body, particularly within the brain, where it plays an essential role in maintaining cellular structure and function. In addition, the blood lipid profile has been recognized as a significant factor influencing cognitive performance. However, the association between the ratio of total cholesterol (TC) to high-density lipoprotein cholesterol (HDL-C) and cognitive function remains unclear.

Methods

This community-based, cross-sectional study was conducted using data from middle-aged and older adults (aged ≥45 years) participating in the China Health and Retirement Longitudinal Study (CHARLS). The primary exposure of interest was the ratio of TC to HDL-C, while the main outcome was cognitive function, assessed using cognition scores. The association between the TC-HDL-C ratio and cognitive performance was examined using multiple linear regression analyses and restricted cubic spline modeling to assess potential nonlinear relationships.

Results

A total of 8,914 participants were included in the analysis. Within a certain range, a higher TC-HDL-C ratio was significantly associated with improved cognitive scores (p < 0.05) among middle-aged and older adults. This relationship remained significant even after adjusting for sociodemographic and health-related factors. Moreover, restricted cubic spline analyses revealed a significant nonlinear association (p for nonlinearity <0.05) between the TC-HDL-C ratio and cognition scores. Subgroup analyses further highlighted differential effects of the TC-HDL-C ratio across specific population subgroups. Sensitivity analyses consistently supported the robustness of the observed relationship between the TC-HDL-C ratio and cognitive function.

Conclusion

Our findings confirm a significant nonlinear relationship between the TC-HDL-C ratio and cognitive performance in middle-aged and elderly individuals, even after adjusting for sociodemographic factors. These results underscore the potential importance of maintaining an appropriate TC-HDL-C ratio to support cognitive health in aging populations.

Cardiometabolic Trajectories Preceding Dementia in Community-Dwelling Older Individuals

Importance

Poor cardiometabolic health is a risk factor associated with cognitive impairment in later life, but it remains unclear whether cardiometabolic trajectories can serve as early markers associated with dementia.

Objective

To compare cardiometabolic trajectories that precede dementia diagnosis with those among individuals without dementia.

Design, Setting, and Participants

This case-control study analyzed a sample drawn from community-dwelling participants in the Aspirin in Reducing Events in the Elderly (ASPREE) study. Recruitment through primary care physicians occurred between March 2010 and December 2014, with participants followed up for a maximum of 11 years. Dementia cases were matched on sociodemographic characteristics and time of diagnosis to dementia-free controls. Data analysis was performed between February and June 2024.

Exposures

Body mass index (BMI), waist circumference, systolic and diastolic blood pressure, glucose levels, high- and low-density lipoprotein (HDL and LDL) and total cholesterol levels, and triglyceride levels were measured repeatedly between 2010 and 2022.

Main Outcomes and Measures

Dementia (Diagnostic and Statistical Manual of Mental Disorders [Fourth Edition] criteria) was adjudicated by an international expert panel.

Results

Among 5390 participants (mean [SD] age, 76.9 [4.8] years; 2915 women [54.1%]), there were 2655 individuals (49.3%) with less than 12 years of education. The study included 1078 dementia cases and 4312 controls. Up to a decade before diagnosis, dementia cases compared with controls had lower BMI for all years from -7 years (marginal estimate, 27.52 [95% CI, 27.24 to 27.79] vs 28.00 [95% CI, 27.86 to 28.14]; contrast P = 002) to 0 years (marginal estimate, 26.09 [95% CI, 25.81 to 26.36] vs 27.22 [95% CI, 27.09 to 27.36]; contrast P < .001) and lower waist circumference for all years from -10 years (marginal estimate, 95.45 cm [95% CI, 94.33 to 96.57 cm] vs 97.35 cm [95% CI, 96.79 to 97.92 cm]; contrast P = .003) to 0 years (marginal estimate, 93.90 [95% CI, 93.15 cm to 94.64 cm] vs 96.67 cm [95% CI, 96.30 to 97.05 cm]; contrast P < .001); cases also had a faster decline in BMI (linear change β, -0.13 [95% CI, -0.19 to -0.08]) and waist circumference (linear change β, -0.30 cm [95% CI, -0.51 to -0.08 cm]). Compared with controls, cases generally had higher HDL levels, in particular from 5 years (marginal estimate, 62.57 mg/dL [95% CI, 61.59 to 63.56 mg/dL] vs 60.84 mg/dL [95% CI, 60.35 to 61.34 mg/dL]; contrast P = .002) to 3 years (marginal estimate, 62.78 mg/dL [95% CI, 61.82 to 63.74 mg/dL] vs 61.08 mg/dL [95% CI, 60.60 to 61.56 mg/dL]; contrast P = .002) before dementia but with a decline in levels just before diagnosis (linear change β, -0.47 mg/dL [95% CI, -0.86 to -0.07 mg/dL]). Dementia cases had lower systolic blood pressure and triglyceride levels in the decade before diagnosis and higher LDL and total cholesterol levels, but these were not significantly different from controls.

Conclusions and Relevance

In this study of older individuals, decline in BMI, waist circumference, and HDL occurred up to a decade before dementia diagnosis. These findings provide insights into cardiometabolic changes preceding dementia and the potential for early monitoring and intervention.

Independent associations of high-density lipoprotein cholesterol and triglyceride levels with Alzheimer's disease and related dementias

INTRODUCTION

We evaluated the independent associations between high-density lipoprotein cholesterol (HDL-C) and triglyceride (TG) levels with Alzheimer's disease and related dementias (ADRD).

METHODS

Among 177,680 members of Kaiser Permanente Northern California who completed a survey on health risks, we residualized TGs and HDL-C conditional on age, sex, and body mass index. We included these residuals individually and concurrently in Cox models predicting ADRD incidence.

RESULTS

Low (hazard ratio [HR] 1.06, 95% confidence interval [CI] 1.02-1.10) and high quintiles (HR 1.07, 95% CI 1.03-1.12) of HDL-C residuals were associated with an increased risk of ADRD compared to the middle quintile. Additional adjustment for TGs attenuated the association with high HDL-C (HR 1.03, 95% CI 0.99-1.08). Low TG residuals were associated with an increased ADRD risk (HR 1.10, 95% CI 1.06-1.15); high TG residuals were protective (HR 0.92, 95% CI 0.88-0.96). These estimates were unaffected by HDL-C adjustment.

DISCUSSION

Low HDL-C and TG levels are independently associated with increased ADRD risk. The correlation with low TG level explains the association of high HDL-C with ADRD.

HIGHLIGHTS

Strong correlations between lipid levels are important considerations when investigating lipids as late-life risk factors for Alzheimer's disease and related dementias (ADRD). Low levels of high-density lipoprotein cholesterol (HDL-C) and triglycerides (TGs) were independently associated with an increased risk of ADRD. We found no evidence for an association between high HDL-C and increased ADRD risk after adjustment for TGs. High levels of TGs were consistently associated with a decreased risk of ADRD. There may be interaction between TG and HDL-C levels, where both low HDL-C and TG levels increase the risk of ADRD compared to average levels of both.

The association of cholesterol levels with memory and memory change over a 14-year period in a US national cohort

INTRODUCTION

The impact of cholesterol on late-life cognition remains controversial. We investigated the association of high-density lipoprotein cholesterol (HDL-C) and non-HDL-C with memory in a nationally representative cohort.

METHODS

Health and Retirement Study (HRS) participants (N = 13,258) aged 50+ (mean age: 67.2 years) followed from 2006 to 2020 provided cholesterol measures every 4 years and cognitive assessments biennially. Linear mixed models predicted memory scores using both baseline and time-updated cholesterol values.

RESULTS

Higher baseline HDL-C (mean: 53.9 mg/dL) predicted better memory scores (β: 0.05, 95% confidence interval [CI]: 0.03 to 0.08), but not memory change. Baseline non-HDL-C (mean: 143 mg/dL) predicted poorer memory scores (β: -0.01, 95% CI: -0.02 to 0.00), but not memory change. Time-updated HDL-C predicted better memory (β: 0.02, 95% CI: 0.00 to 0.04), but non-HDL-C showed no such associations.

DISCUSSION

While higher peripheral HDL-C is linked to better memory, the small effect sizes and absence of associations of HDL-C and non-HD-CL with memory change suggests that peripheral cholesterol has a small effect on the variation of memory scores.

Highlights

Higher HDL-C levels predict better memory scores but not memory change across 14 years of follow-up.Baseline higher LDL-C levels predict poorer memory scores across time, but not memory change.The small effects and absence of consistent association between cholesterol levels and memory change suggest that cholesterol plays a minor role in cognitive decline.

Elevated blood glucose levels are associated with the progression of brain hypometabolism, and HDL-C and APOE4 add to this association

Background

Brain glucose hypometabolism has consistently been found in neurodegenerative disorders, including Alzheimer's disease (AD). High blood glucose and HDL cholesterol (HDL-C) levels have also been linked to neurodegeneration and AD. However, there is limited understanding of the relationships between dementia-related risk factors in the brain and blood.

Methods

A linear mixed model was used to examine the relationship between blood glucose and HDL-C levels and the progression of brain hypometabolism, adjusting for APOE4 and other clinical covariates. The hypometabolic convergence index (HCI) was measured by fluorodeoxyglucose-18 (FDG) positron emission tomography (PET) in participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Data visualizations were generated to understand the joint effects of plasma glucose, HDL-C, and APOE4 on HCI.

Results

There were 336 individuals (781 observations), of whom 22.62% had AD. The majority were male (63.98%) and of white race, and 48.51% were carriers of APOE4. Over time, high blood glucose level was associated with the progression of brain glucose hypometabolism (β=0.33, 95% CI: 0.02, 0.64, p<0.05). A high plasma HDL-C level (β=1.22, 95% CI: 0.09, 2.35, p<0.05), more study visits (β=1.67, 95% CI: 1.37, 1.98, p<0.001), and being an APOE4 allele carrier (β=1.29, 95% CI: 0.15, 2.42, p<0.05) were also significant predictors of brain hypometabolism progression. APOE4 carrier status and number of visits account for the largest proportion of the variance from the fixed effects model. Random effects due to participant characteristics and fixed effects together accounted for 95.2% of the model variance. Subgroup analysis revealed that these effects were observed only in those without AD.

Conclusion

High plasma glucose levels facilitated the progression of brain hypometabolism. The effect was more prominent in the APOE4 double-carriers with elevated HDL-C. Elevated blood glucose may reflect systemic insulin resistance, which could impair brain glucose uptake, resulting in brain hypometabolism. Controlling blood glucose and HDL-C levels in APOE4 carriers may improve brain metabolism, potentially delaying the onset of dementia.

Cognitive impairment and depression precede increased HDL-C levels in middle-aged and older Chinese adults: cross-lagged panel analyses

BACKGROUND

High-density lipoprotein cholesterol (HDL-C) is widely recognized for its protective effects against cognitive decline. However, recent studies have presented conflicting results, with some suggesting no significant cognitive benefits or even an increased risk of dementia associated with high HDL-C levels. For those who suffer from depression, the cognitive benefits of HDL-C may be diminished or reversed. The purpose of this study is to investigate the associations between HDL-C, cognitive ability, and depressive symptoms in middle-aged and older Chinese adults.

METHODS

The datasets utilized were sourced from the China Health and Retirement Longitudinal Study (CHARLS) for the years 2011 and 2015, comprising 4,302 participants. Cross-lagged models were employed to explore the temporal sequence between cognitive performance and HDL-C levels, and to examine the interplay among depression, cognition, and HDL-C. Confounding factors such as sociodemographic characteristics, sleep conditions, and history of chronic diseases were controlled for.

RESULTS

The analysis revealed unidirectional effects of baseline impaired cognition and greater severity of depression on increased HDL-C levels at follow-up (β =  - 0.036 and β = 0.028, respectively, P < 0.05). However, higher baseline HDL-C levels did not significantly predict cognitive performance or depression 4 years later (β =  - 0.008 and β = 0.023, respectively, P > 0.05). Depressive symptoms and cognition were found to have a significant bidirectional association (β =  - 0.026 and β =  - 0.053, respectively, P < 0.05).

CONCLUSIONS

Cognitive impairment and depression are associated with higher HDL-C levels, whereas higher HDL-C levels do not appear to protect against cognitive decline or depressive symptoms. These findings underscore the importance of preserving cognitive and mental health, which may lower the likelihood of cardiovascular disease and dementia. Future studies should validate these findings and develop targeted interventions tailored to specific populations.

Reevaluating elevated HDL cholesterol levels in healthy older persons as a risk factor for various disease states

This article reviews the role of high-density lipoprotein cholesterol (HDL-C) in the elderly population, questioning the established view that advocates the ubiquitous health benefits of HDL cholesterol. High levels of HDL-C have been found to be associated with an increased risk of debilitating fractures, dementia, and cardiovascular disease, predominantly affecting older men, through the use of large population-based studies such as the ASPREE trial and the UK Biobank. Possible mechanisms are closely linked to cholesterol crystallization and altered HDL particle function. These findings call for a refinement of the understanding of high-density lipoprotein cholesterol (HDL-C), which implies adjustments to clinical guidelines and risk assessment strategies in older populations.