Outcome age-based prediction of successful cognitive aging by total cholesterol

Exploration for the reference interval of C-reactive protein in the Chinese longevity people over 90 years of age

BACKGROUND

Older individuals tend to develop chronic inflammation. As a commonly used nonspecific inflammatory marker, C-reactive protein (CRP) can predict metabolic syndrome, cardiovascular diseases, etc. However, little is known about CRP levels in longevity people.

OBJECTIVES

Investigate the distribution and correlates of CRP and provide a reference for the establishment of normal interval values in Chinese longevity people over 90 years of age.

METHODS

We performed a correlation analysis to evaluate the correlation between CRP levels and longevity based on the basic demographic characteristics, anthropometric measurements and blood data of 4,418 participants in the 2015 China Health and Retirement Longitudinal Study and 636 participants in an ongoing longitudinal study of natural longevity people in Guangxi. On this basis, the CRP reference interval for longevity was explored.

RESULTS

The CRP concentration was significantly different among the three age groups, with a median of 3.80 mg/L for those older than 90 years, which was significantly higher than that for those aged 45-64 years (median 1.20 mg/L, p < 0.001) and 65-89 years (median 1.30 mg/L, p < 0.001). Body mass index, waist circumference, the waist-to-height ratio, systolic blood pressure, diastolic blood pressure, and fasting and postprandial blood glucose, triglyceride, total cholesterol and low-density lipoprotein cholesterol levels were positively correlated with CRP levels, while fasting high-density lipoprotein cholesterol was negatively correlated with CRP levels. The CRP reference interval (RI) value in longevity people was 0.25-9.22 mg/L.

CONCLUSION

The concentrations of CRP increased with advancing age, and the CRP reference interval was different between older and younger adults.

Total Cholesterol and APOE-Related Risk for Alzheimer's Disease in the Alzheimer's Disease Neuroimaging Initiative

BACKGROUND

APOEɛ4 allele confers greatest genetic risk for Alzheimer's disease (AD), yet mechanisms underlying this risk remain elusive. APOE is involved in lipid metabolism, and literature suggest relationships between high total cholesterol, APOE, and AD. Further investigation is needed to elucidate the potential role of total cholesterol in AD risk.

OBJECTIVE

To investigate the relationship between total cholesterol and APOE-related AD risk in the Alzheimer's Disease Neuroimaging Initiative.

METHODS

Participants (N = 1,534) were classified as controls (cognitively normal; N = 404), early mild cognitive impairment (MCI; N = 294), late MCI (N = 539), or AD (N = 297). Total cholesterol levels were compared across APOE genotype and diagnosis. Mendelian randomization was performed to examine causality between total cholesterol and AD risk using APOE as a genetic instrument.

RESULTS

Total cholesterol was higher in APOE4+ compared to APOE3 and APOE2+ (ps < 0.04) carriers. Those with AD and late MCI (ps < 0.001) had higher total cholesterol than the control group. Comparing APOE4+ to APOE3 carriers, the predicted odds ratios per mg/dL greater total cholesterol were 1.11 for MCI (95% confidence interval, 1.04-7.32), 1.05 for early MCI (1.01-3.22), 1.13 for late MCI (1.05-11.70), 1.21 for AD (1.09-54.05), and 1.13 for composite dementia (MCI or AD; 1.06-11.59) (ps < 0.05, F-statistics > 10).

CONCLUSION

Higher total cholesterol may be a significant contributor to AD risk, particularly in APOE4 carriers who, based on existing literature, tend to have impaired cholesterol metabolism. Our findings highlight a possible mechanism by which APOE confers AD risk and indicate potential for AD risk modification through maintenance of healthy total cholesterol levels.

Variability in Cardiometabolic and Inflammatory Parameters and Cognitive Decline

INTRODUCTION

The relationship between variability in cardiometabolic and inflammatory parameters and cognitive changes is unknown. This study investigates the association of visit-to-visit variability in BMI, mean arterial pressure, total cholesterol, triglycerides, HbA1c, high-sensitivity C-reactive protein, ferritin, and fibrinogen with cognitive decline.

METHODS

This population-based cohort study included 2,260 individuals (mean age=63.0 [SD=7.5] years) free of cognitive diseases who underwent ≥3 clinical measurements from 2004 to 2019. Variability was expressed as variability independent of the mean across visits. Participants were divided on the basis of quartiles of variability score, a scoring system generated to explore the composite effect of parameter variability (range=0-24), where 0 points were assigned for Quartile 1, 1 point was assigned for Quartile 2, 2 points were assigned for Quartile 3, and 3 points were assigned for Quartile 4, each for the variability of 8 parameters measured as variability independent of the mean. Linear mixed models evaluated the longitudinal associations with cognitive decline in memory and verbal fluency. All analyses were conducted in 2020-2021.

RESULTS

Higher BMI, mean arterial pressure, total cholesterol, HbA1c, and ferritin variability were linearly associated with cognitive decline irrespective of their mean values. In addition, participants in the highest quartile of variability score had a significantly worse cognitive decline rate in memory (-0.0224 points/year, 95% CI= -0.0319, -0.0129) and verbal fluency (-0.0088 points/year, 95% CI= -0.0168, -0.0008) than those in the lowest quartile.

CONCLUSIONS

A higher variability in cardiometabolic and inflammatory parameters was significantly associated with cognitive decline. Stabilizing these parameters may serve as a target to preserve cognitive functioning.

What have we learned from cognition in the oldest-old

PURPOSE OF REVIEW

People over 90 are the fastest growing segment of the population with the highest rates of dementia. This review highlights recent findings that provide insight to our understanding of dementia and cognition at all ages.

RECENT FINDINGS

Risk factors for Alzheimer's disease (AD) and dementia differ by age, with some factors, like the development of hypertension, actually becoming protective in the oldest-old. At least half of all dementia in this age group is due to non AD pathologies, including microinfarcts, hippocampal sclerosis and TDP-43. The number of pathologic changes found in the brain is related to both risk and severity of dementia, but many people in this age group appear to be 'resilient' to these pathologies. Resilience to Alzheimer pathology, in part, may be related to absence of other pathologies, and imaging and spinal fluid biomarkers for AD have limited utility in this age group.

SUMMARY

Studies of dementia in the oldest-old are important for our understanding and eventual treatment or prevention of dementia at all ages.

Trends in Prevalence of Dementia for People Accessing Aged Care Services in Australia

BACKGROUND

Studies in some high-income countries have reported a potential decline in the prevalence of dementia. Improvements in cardiovascular health may be contributing to this decline. The objective was to examine trends in prevalence of dementia and survival with dementia for people accessing aged care in Australia.

METHODS

A retrospective study of older people who accessed long-term care 2008-2014 (n = 348,311) and home care 2005-2014 (n = 188,846) in Australia was developed. The age- and sex-standardized prevalence for dementia by year of access to aged care was determined using direct standardization. Generalized linear models were used to determine change in the prevalence of dementia over time and change in 1-year mortality for people who accessed long-term care.

RESULTS

The age- and sex-standardized prevalence (95% confidence interval) of dementia declined from 50.0% (49.6, 50.5) in 2008 to 46.6% (46.0, 47.2) in 2014 for people accessing long-term care (absolute change 2008-2014: -3.8 [-4.6, -3.1]) and for people accessing home care from 25.9% (25.0, 26.5) in 2005 to 20.9% (20.2, 21.7) in 2014 (absolute change 2005-2014: -5.2 [-6.2, -4.1]). This decline in dementia occurred in concurrence with a decline in cerebrovascular disease in long-term care but despite the prevalence of hypertension, diabetes, high cholesterol, malnutrition, obesity, depression, and head injury increasing. For people accessing long-term care, 1-year mortality remained stable over time.

CONCLUSIONS

The decline in prevalence of dementia for people accessing aged care services in Australia is critical to future projection estimates and for planning of services. Further research to determine contributing factors to the decline is needed.

Associations of hemoglobin A1c with cognition reduced for long diabetes duration

Introduction

Associations of some risk factors with poor cognition, identified prior to age 75, are reduced or reversed in very old age. The Protected Survivor Model predicts this interaction due to enhanced survival of those with extended risk factor duration. In a younger sample, this study examines the association of cognition with the mean hemoglobin A1c risk factor over the time at risk, according to its duration.

Methods

The interaction of mean hemoglobin A1c (average = 9.8%), evaluated over duration (average = 116.8 months), was examined for overall cognition and three cognitive domains in a sample of 150 “young-old” veterans (mean age = 70) with type 2 diabetes.

Results

The predicted interactions were significant for overall cognition and attention, but not executive functions/language and memory.

Discussion

Findings extend the Protected Survivor Model to a “young-old” sample, from the very old. This model suggests focusing on individuals with good cognition despite prolonged high risk when seeking protective factors.