Association between the triglyceride-glucose index and cognitive impairment in China: a community population-based cross-sectional study.

INTRODUCTION: Insulin resistance (IR) is a feature of metabolic syndrome and plays an important role in cognitive impairment (CI). The triglyceride-glucose (TyG) index is a convenient and cost-effective surrogate for assessing IR. This study aimed to assess the association between the TyG index and CI. METHODS: This community population-based cross-sectional study used a cluster-sampling methodology. All participants underwent the education-based Mini-Mental State Examination (MMSE), and those with CI were identified using standard thresholds. The fasting blood triglyceride and glucose levels were measured in the morning, and the TyG index was calculated as ln (½ fasting triglyceride level [mg/dL] × fasting blood glucose level [mg/dL]). Multivariable logistic regression and subgroup analysis were used to assess the relationship between the TyG index and CI. RESULTS: This study included 1484 subjects, of which 93 (6.27%) met the CI criteria. Multivariable logistic regression showed that CI incidence increased by 64% per unit increase in the TyG index (odds ratio [OR] = 1.64, 95% confidence interval [CI]: 1.02-2.63, p = 0.042). CI risk was 2.64-fold higher in the highest TyG index quartile compared to the lowest TyG index quartile (OR = 2.64, 95% CI: 1.19-5.85, p = 0.016). Finally, interaction analysis showed that sex, age, hypertension, and diabetes did not significantly affect the association between the TyG index and CI. CONCLUSION: The present study suggested that an elevated TyG index was associated with a higher CI risk. Subjects with a higher TyG index should manage and treat at an early stage to alleviate the cognitive decline.

Associations among Body Mass Index, Waist-to-Hip Ratio, and Cognitive Impairment Tend to Follow an Opposite Trend and Are Sex Specific: A Population-Based Cross-Sectional Study in a Rural Area of Xi'an, China.

INTRODUCTION: The relationship between obesity and cognitive impairment (CI) is highly heterogeneous in previous studies, which may be due to insufficient consideration of anthropometric indicators and sex. This study compared the cross-sectional relationships among body mass index (BMI), waist-to-hip ratio (WHR), and CI among people aged ≥40 years, and sex-specific relationships were also considered. METHODS: This was a population-based cross-sectional study with a cluster sampling design. CI was defined as a Mini-Mental State Examination score lower than the cutoff value. Multivariate logistic regression was used. BMI and WHR were fitted as both restricted cubic splines and categorical data. Stratified analysis and interaction analysis were performed to explore the sex-specific relationship. RESULTS: A total of 1,792 subjects (40.5% male) were analyzed, and 230 were confirmed to have CI. The relationships among BMI, WHR, and CI were significant (poverall = 0.023, pnonlinear = 0.097; poverall = 0.017, pnonlinear = 0.078, respectively) but exhibited an opposite trend in the total population in the analyses with BMI and WHR as restricted cubic splines. Further categorical analyses showed that subjects with a BMI <23 kg/m2 tended to have a higher risk of CI than those with BMI ≥23 kg/m2 (16.2% vs. 11.8%, p = 0.017; OR = 1.366 [0.969-1.926], p = 0.075), and subjects with a WHR >0.92 had a significantly higher risk of CI than those with a WHR ≤0.92 (11.7% vs. 16.2%, p = 0.011; OR = 1.619 [1.161-2.258], p = 0.005). In addition, the relationship between a low BMI and CI was more significant in males (p = 0.034), while the relationship between a high WHR and CI was more significant in females (p = 0.002). Further studies are needed to confirm the sex differences because of the marginal significance result in the interaction analysis (p = 0.051 for interaction term BMI × sex; p = 0.056 for interaction term WHR × sex). CONCLUSION: The relationships among BMI, WHR, and CI exhibit an opposite trend. A low BMI or high WHR was positively associated with CI, which was more prominent in males for a low BMI and females for a high WHR.

The relationship between blood lipids and plasma amyloid beta is depend on blood pressure: a population-based cross-sectional study.

BACKGROUND: It is believed that deposition of amyloid beta (Aß) in the brain is the central pathological changes of Alzheimer's disease (AD), which triggers a series of pathological processes. However, the relationship between dyslipidemia and AD is uncertain. Considering the peripheral Aß levels are related to brain Aß deposition, we explore the relationships between blood lipids and plasma Aß. METHODS: Participants who lived in the selected village of Xi'an for more than 3 years were enrolled, aged 40-85 years (n = 1282, 37.9% male). Fasting blood lipid, plasma Aß levels, basic information and living habits were measured. Multiple linear regressions were used. RESULTS: In total population, blood lipids were not associated with plasma Aß. After stratified by blood pressure, serum total cholesterol (TC) and low-density lipoprotein (LDL-c) were positively associated with plasma Aß42 levels (ßTC = 0.666, PTC = 0.024; ßLDL-c = 0.743, PLDL-c = 0.011, respectively) in normal blood pressure. LDL-c was negatively associated with plasma Aß40 levels (ß = - 0.986, P = 0.037) in high blood pressure. CONCLUSION: Elevated plasma Aß42 levels are associated with higher TC and LDL-c in normal blood pressure. Elevated plasma Aß40 levels are associated with lower LDL-c in high blood pressure. This indicated that the relationships between blood lipids and plasma Aß were confounded by blood pressure.

Nonlinear relationship between pulse pressure and risk of cognitive impairment: A 4-year community-based cohort study in Xi'an, China.

OBJECTIVES: It has been known that pulse pressure (PP) is a risk factor for cardiovascular disease and stroke, however, the relationship between PP and cognitive impairment is unclear. METHODS: This was a community-based cohort study. Participates were followed-up for 4 years and new-onset cognitive impairment was diagnosed. Multivariable logistic regression and restricted cubic spline (RCS) were used to investigate the relationship between PP and cognitive impairment. Propensity score matching (PSM) and sensitivity analysis among ApoEε4 non-carriers were performed to confirm the results. RESULTS: 1462 participants were included at baseline and 1173 completed the follow-up. There were 42 (3.5%) new-onset cognitive impairment of whom 31 were diagnosed with MCI and 11 with dementia during the follow-up. Multivariable logistic regression analysis showed that PP was positively associated with cognitive impairment (OR = 2.853, 95% CI 1.079-7.548, p = 0.035), and RCS suggested a non-linear relationship (Pnon-linear = 0.034). The risk of cognitive impairment merely changed when the PP was below about 46.7 mmHg and increased rapidly thereafter. After the covariates were well balanced using PSM (standardized mean differences <0.1 for all covariates), logistic regression analysis revealed the risk of cognitive impairment was still higher for those with high PP (OR = 3.369, 95% CI 1.202-9.441, p = 0.021). Sensitivity analysis showed consistent results with primary analysis. CONCLUSION: PP is associated with cognitive impairment in a non-linear manner among middle-aged and elderly. The risk of cognitive impairment increases rapidly when PP exceeds about 46.7 mmHg, which may be informative for subsequent research of PP control ranges.

The Association of Plasma Amyloid-ß and Cognitive Decline in Cognitively Unimpaired Population.

Purpose: This study investigates the relationship between baseline plasma Aß and cognitive decline during follow-up in cognitively unimpaired population. Materials and Methods: Cognitively unimpaired population was selected from people who lived in the suburbs of Xi'an, China. The levels of plasma Aß1-42 and Aß1-40 were tested using commercial enzyme-linked immunosorbent assay (ELISA). The mini-mental state examination (MMSE) and neuropsychological battery were used to assess cognition. Two years later, MMSE was tested again, and significant cognitive decline was defined as a decrease in MMSE scores ≥5 points. Logistic regression analysis was performed to analyze the relationship between baseline plasma Aß and cognitive change during the two-year follow-up. Results: A total of 1144 participants completed the study, among whom 59 subjects (5.2%) presented significant cognitive decline. The high plasma Aß1-42 level group had more significant cognitive decline (P = 0.023). Multivariable logistic regression analysis showed that significant cognitive decline was associated with the high levels of baseline plasma Aß1-42 (OR = 1.043, 95% CI: 1.005-1.083, P = 0.026). However, significant cognitive decline was not associated with baseline plasma Aß1-40 levels and Aß1-42 /Aß1-40 ratio. Conclusion: Population with high level of baseline plasma Aß1-42 manifested significant cognitive decline over 2 years; however, further investigation on the dynamics of plasma Aß and long-term follow-up are needed.

Peripheral Transport Proteins Were Associated with 4-Year Cognitive Decline in APOE ɛ4 Non-Carriers: A Longitudinal, Population-Based Study.

BACKGROUND: Soluble low-density lipoprotein receptor-related protein-1 (sLRP1) and soluble receptor of advanced glycation end products (sRAGE) play major roles in peripheral clearance of amyloid-ß (Aß). OBJECTIVE: To determine the relationship between baseline sLRP1/sRAGE and early cognitive decline in a longitudinal study and explore the possible effect of apolipoprotein E (APOE) on their association. METHODS: Cognitively normal subjects were followed-up for 4 years. The baseline plasma levels of sLRP1 and sRAGE were measured using commercial ELISA kits. Global cognition was evaluated by Mini-Mental State Examination (MMSE), and cognitive decline was defined as a ≥2-point decrease of MMSE after 4 years. The association between baseline sLRP1/sRAGE and 4-year cognitive decline were analyzed using logistic regression analysis. Interaction analysis was performed to discover the potential effect of APOE genotype on the relationship. RESULTS: 769 participants were included in the final analysis, with 122 subjects (15.86%) were cognitive decline. Baseline sLRP1/sRAGE levels were not associated with 4-year cognitive decline after multivariable adjustments in the total cohort. However, there was significant interaction effect between sRAGE and APOE genotype on cognitive decline (adjusted odds ratio [OR] = 2.09, 95% confidence interval [CI]: 1.13-3.86, p = 0.019). Lower levels of sRAGE were associated with increased risk of cognitive decline among APOE ɛ4 non-carriers (adjusted OR = 1.60, 95% CI: 1.04-2.48, p = 0.034). CONCLUSION: Individuals with lower levels of sRAGE had an increased risk of 4-year cognitive decline in APOE ɛ4 non-carriers, indicating that the association between sRAGE and cognitive decline might depend on the APOE genotype. However, the specific mechanisms need to be further elucidated.

Pulse Pressure Is Associated with Rapid Cognitive Decline over 4 Years: A Population-Based Cohort Study.

Aiming to investigate the relationship between pulse pressure (PP) and cognitive decline, cognitively normal subjects from a community-based longitudinal cohort were followed-up for 4 years. The Mini-Mental State Examination (MMSE) was used to evaluate global cognitive function, and a ≥2-point decrease in the MMSE score from baseline was defined as cognitive decline. Restricted cubic spline, multivariable linear regression and logistic regression were used to investigate the relationship between PP and cognitive decline. A total of 1173 participants completed the follow-up, and 205 (17.5%) met the criteria for cognitive decline. Restricted cubic splines showed no nonlinear relationship between PP and ΔMMSE (Poverall = 0.037, Pnon-linear = 0.289) or cognitive decline (Poverall = 0.003, Pnon-linear = 0.845). Multivariable linear regression analysis showed that PP was positively related to ΔMMSE (b = 0.021, p = 0.020). Multivariable logistic regression analysis showed that PP was positively associated with cognitive decline (OR = 1.020, p = 0.023). A stratified analysis found an association between PP and cognitive decline in participants who were aged ≤65 years, male, and APOEε4 noncarriers and who had school education ≤6 years or hypertension. A sensitivity analysis after propensity-score matching did not alter our findings. These findings highlight that elevated PP is associated with rapid cognitive decline, particularly in males, middle-aged, low-educated, hypertensive individuals and APOEε4 noncarriers.

Blood Pressure Level Is Associated With Changes in Plasma Aß1 -40 and Aß1-42 Levels: A Cross-sectional Study Conducted in the Suburbs of Xi'an, China.

Objectives: Amyloid-ß (Aß) deposition in the brain is the hallmark of Alzheimer's disease (AD) pathology. Hypertension is a risk factor for AD, but the effects of hypertension on Aß deposition are not fully determined. Considering peripheral Aß closely relates to Aß deposition in the brain, we investigated the relationships between blood pressure (BP) level and plasma Aß concentrations. Methods: One-thousand and sixty-nine participants (age above 45) from a village in the suburbs of Xi'an, China were enrolled. Questionnaires and validated Chinese versions of the Mini-Mental State Examination (MMSE) were used to collect information about vascular risk factors and assess cognition function. The apolipoprotein E (ApoE) genotype was detected using PCR and sequencing. Plasma Aß levels were measured using ELISA. The associations between BP and plasma Aß levels were analyzed by using multivariate linear regression. Results: Plasma Aß1-40 level was higher in high BP group than that in normal BP group (53.34 ± 8.50 pg/ml vs. 51.98 ± 8.96 pg/ml, P = 0.013), in high SBP group than that in normal SBP group (53.68 ± 8.69 pg/ml vs. 51.88 ± 8.80 pg/ml, P = 0.001) and in high MABP group than that in normal MABP group (54.05 ± 8.78 pg/ml vs. 52.04 ± 8.75 pg/ml, P = 0.001). After controlling for the confounding factors, SBP (b = 0.078, P < 0.001), DBP (b = 0.090, P = 0.008) and MABP (b = 0.104, P < 0.001) correlated with plasma Aß1-40 level positively in ApoE ε4 non-carriers, but not ApoE ε4 carriers. Conclusions: Elevated BP levels were associated with increased plasma Aß1-40 levels in middle-aged and elderly ApoE ε4 non-carriers.