Association Between Variation in Red Cell Size and Multiple Aging-Related Outcomes

Elevated mtDNA content in RBCs promotes oxidative stress may be responsible for faster senescence in men

BACKGROUND

Both we and others have found that RBC counts are significantly lower in older compared to younger. However, when gender is factored in, a significant age-related decrease of RBC counts is observed only in men but not in women.

METHODS

qPCR and confocal microscopy were used to detect the presence of mtDNA in RBCs. Flow cytometry and specific inhibitors were used to determine how RBCs uptake cf-mtDNA. The peripheral blood was collected from 202 young adults and 207 older adults and RBC and plasma were isolated. The levels of TLR9+RBCs and apoptotic RBCs after uptake of cf-mtDNA by RBCs were measured by flow cytometry. The kit detects changes in SOD and MDA levels after cf-mtDNA uptake by RBCs. Young RBCs (YR) and old RBCs (OR) from single individuals were separated by Percoll centrifugation.

RESULTS

We found a significant decrease in RBC counts and a significant increase in the RDW with aging only in men. We also found that significantly elevated mtDNA content in RBCs was observed only in men during aging and was not found in women. Further studies demonstrated that RBCs could take up cf-mtDNA via TLR9, and the uptake of mtDNA might lead to a decrease in the RBC number and an increase in RDW due to an increase of oxidative stress.

CONCLUSIONS

The RBC mtDNA content might be a potential marker of RBC aging and the elevated RBC mtDNA content might be the cause of faster senescence in males than females.

A biological age model based on physical examination data to predict mortality in a Chinese population

Biological age could be reflective of an individual's health status and aging degree. Limited estimations of biological aging based on physical examination data in the Chinese population have been developed to quantify the rate of aging. We developed and validated a novel aging measure (Balanced-AGE) based on readily available physical health examination data. In this study, a repeated sub-sampling approach was applied to address the data imbalance issue, and this approach significantly improved the performance of biological age (Balanced-AGE) in predicting all-cause mortality with a 10-year time-dependent AUC of 0.908 for all-cause mortality. This mortality prediction tool was found to be effective across different subgroups by age, sex, smoking, and alcohol consumption status. Additionally, this study revealed that individuals who were underweight, smokers, or drinkers had a higher extent of age acceleration. The Balanced-AGE may serve as an effective and generally applicable tool for health assessment and management among the elderly population.

Association of hemoglobin-to-red blood cell distribution width ratio and depression in older adults: A cross sectional study

BACKGROUND

The association between hemoglobin-to-red blood cell distribution width ratio (HRR) and the depression in old adults was not clear.

METHODS

We extracted data on depression, general characteristics, lifestyle, medical history, drug use, and blood indicators from the National Health and Nutrition Examination Survey 2005-2018 to investigate the relationship between HRR and depression.

RESULTS

A total of 4141 individuals were evaluated, among whom 266 (6.4 %) were identified as having depression. HRR was significantly lower in the low depression group, and Spearman correlation analysis revealed an inverse association between HRR and depression scores (r = -0.148, P < 0.001). Multiple linear regression showed that HRR was associated with depression after adjusted for general characteristics, life style, medical history, drug use and blood indicators (P = 0.010). ROC analysis demonstrated that in participants with depression, the area under the curve (AUC) for HRR was 0.612, surpassing both Hb(0.586) and RDW(0.401). These findings were statistically significant (P < 0.05).

LIMITATIONS

Only participants aged 65-79 years are selected for this study and this was a cross-sectional study that can only represent an association between HRR and depression, but not a cause-and-effect relationship.

CONCLUSIONS

HRR, being more potent than Hb or RDW, emerges as an independent risk factor for depression. It has the potential to facilitate early depression detection, aiding in the prevention of clinical deterioration or relapses, and could also serve as a viable treatment target.

Lower haemoglobin-to-red blood cell distribution width ratio is independently associated with frailty in community-dwelling older adults: a cross-sectional study

OBJECTIVES

The importance of blood cell markers in frailty has been studied. However, research on haemoglobin-to-red blood cell distribution width ratio (HRR) and frailty in older persons is still limited. We investigated the association between HRR and frailty in older adults.

DESIGN

Cross-sectional population-based study.

SETTING

Community-dwelling older adults older than 65 years were recruited from September 2021 to December 2021.

PARTICIPANTS

A total of 1296 community-dwelling older adults (age ≥65 years) in Wuhan were included in the study.

MAIN OUTCOME MEASURES

The main outcome was the presence of frailty. The Fried Frailty Phenotype Scale was used to evaluate the frailty status of the participants. Multivariable logistic regression analysis was performed to determine the relationship between HRR and frailty.

RESULTS

A total of 1296 (564 men) older adults were included in this cross-sectional study. Their mean age was 70.89±4.85 years. Receiver operating characteristic curve analysis showed that HRR is a good predictor of frailty in older people, the area under the curve (AUC) was 0.802 (95% CI: 0.755 to 0.849), and the highest sensitivity was 84.5% and the specificity was 61.9% with the optimal critical values 9.97 (p<0.001). Multiple logistic regression analysis indicated that lower HRR (<9.97) (OR: 3.419, 1.679 to 6.964, p=0.001) is independently associated with frailty in older people, even after adjusting confounding factors.

CONCLUSION

Lower HRR is closely associated with an increased risk of frailty in older people. Lower HRR may be an independent risk factor for frailty in community-dwelling older adults.

Promising applications of red cell distribution width in diagnosis and prognosis of diseases with or without disordered iron metabolism

Many indicators, including red cell distribution width (RDW) and iron metabolism, are sensitive to a variety of risk factors, and are associated with the pathological alterations and disease onset. RDW reflects the degree of heterogeneous volumes of peripheral red blood cells (RBCs). It has been well-known that increased RDW indicates iron deficiency anemia, hemolytic anemia, ineffective erythropoiesis, and shorten lifespan of RBCs. Increased RDW is also prevalent in various non-anemic pathological conditions and diseases. We here review the factors affecting RDW, particularly disordered iron metabolism, chronic inflammation, and oxidative stress, and recapitulate the interplays among these factors. Furthermore, we review the application of increased RDW together with disordered iron homeostasis and the deregulations of hepcidin expression and ferritin levels in the diagnoses and prognosis of anemic and nonanemic diseases. RDW is inexpensive and readily available and may be valuable in adding to the diagnosis and monitoring of many pathological conditions. RDW combined with other indicators, for example, hepcidin and ferritin levels, should be utilized more frequently in clinical practice.

Red cell distribution width and mortality in older patients with frailty in the emergency department

BACKGROUND

The red cell distribution width (RDW) reflects the degree of heterogeneity of red blood cells. Elevated RDW is associated both with frailty and with increased mortality in hospital-admitted patients. In this study we evaluate whether high RDW values are associated with mortality in older emergency department (ED) patients with frailty, and if the association is independent of the degree of frailty.

METHODS

We included ED patients with the following criteria: ≥ 75 years of age, Clinical Frailty Scale (CFS) score of 4 to 8, and RDW % measured within 48 h of ED admission. Patients were allocated to six classes by their RDW value: ≤ 13%, 14%, 15%, 16%, 17%, and ≥ 18%. The outcome was death within 30 days of ED admission. Crude and adjusted odds ratios (OR) with 95% confidence intervals (CI) for a one-class increase in RDW for 30-day mortality were calculated via binary logistic regression analysis. Age, gender and CFS score were considered as potential confounders.

RESULTS

A total of 1407 patients (61.2% female), were included. The median age was 85 with an inter-quartile range (IQR) of 80-89, median CFS score 6 (IQR: 5-7), and median RDW 14 (IQR: 13-16). Of the included patients, 71.9% were admitted to hospital wards. A total of 85 patients (6.0%) died during the 30-day follow-up. Mortality rate was associated with RDW increase (p for trend < .001). Crude OR for a one-class increase in RDW for 30-day mortality was 1.32 (95% CI: 1.17-1.50, p < .001). When adjusted for age, gender and CFS-score, OR of mortality for one-class RDW increase was still 1.32 (95% CI: 1.16-1.50, p < .001).

CONCLUSION

Higher RDW values had a significant association with increased 30-day mortality risk in frail older adults in the ED, and this risk was independent of degree of frailty. RDW is a readily available biomarker for most ED patients. It might be beneficial to include it in risk stratification of older frail ED patients to identify those who could benefit from further diagnostic assessment, targeted interventions, and care planning.

Joint inference of physiological network and survival analysis identifies factors associated with aging rate

We describe methodology for joint reconstruction of physiological-survival networks from observational data capable of identifying key survival-associated variables, inferring a minimal physiological network structure, and bridging this network to the Gompertzian survival layer. Using synthetic network structures, we show that the method is capable of identifying aging variables in cohorts as small as 5,000 participants. Applying the methodology to the observational human cohort, we find that interleukin-6, vascular calcification, and red-blood distribution width are strong predictors of baseline fitness. More important, we find that red blood cell counts, kidney function, and phosphate level are directly linked to the Gompertzian aging rate. Our model therefore enables discovery of processes directly linked to the aging rate of our species. We further show that this epidemiological framework can be applied as a causal inference engine to simulate the effects of interventions on physiology and longevity.

The Association Between Red Cell Distribution Width and Grip Strength in Older Adults

Background The red cell distribution width (RDW), an index of variation of erythrocyte volume (anisocytosis), has traditionally been used in the differential diagnosis of anemia. However, recent studies reported that increased RDW may be associated with adverse aging-related health outcomes. Methods The present cross-sectional study analyzed data from the National Health and Nutrition Examination Survey to examine the association between RDW categories (≤ 13.0%, 13.1 - 14.0%, 14.1 - 15.0%, ≥ 15.1%) and maximum grip strength (GS) (kg) in a nationally representative sample of adults aged 60 years and older. Anemia was defined according to the WHO criteria as a hemoglobin concentration of < 13 g/dl in men and < 12 g/dl in women. Results A total of 2,955 participants with a mean age of 69.3 years represented the study sample. General linear models demonstrated that men and women with RDW ≥ 15.1% were 3.2 kg and 1.4 kg weaker than their counterparts with RDW ≤ 13.0%, respectively. Notably, non-anemic older men in the highest RDW category had a mean GS 3.9 kg lower than those in the lowest RDW category. In contrast, this association was attenuated in women without anemia. Conclusion RDW was inversely associated with GS, particularly in older men. Moreover, this association remained unchanged even among men without anemia.

Cellular enlargement - A new hallmark of aging?

Years of important research has revealed that cells heavily invest in regulating their size. Nevertheless, it has remained unclear why accurate size control is so important. Our recent study using hematopoietic stem cells (HSCs) in vivo indicates that cellular enlargement is causally associated with aging. Here, we present an overview of these findings and their implications. Furthermore, we performed a broad literature analysis to evaluate the potential of cellular enlargement as a new aging hallmark and to examine its connection to previously described aging hallmarks. Finally, we highlight interesting work presenting a correlation between cell size and age-related diseases. Taken together, we found mounting evidence linking cellular enlargement to aging and age-related diseases. Therefore, we encourage researchers from seemingly unrelated areas to take a fresh look at their data from the perspective of cell size.

Red cell distribution width, anemia, and lower-extremity physical function among rural-dwelling older adults

BACKGROUND

Elevated red cell distribution width (RDW) has been associated with degenerative conditions in aging.

AIMS

We aimed to evaluate the associations of RDW and anemia with lower-extremity physical function among rural-dwelling older adults.

METHODS

This population-based cross-sectional study included 5093 rural residents (age ≥ 60 years, 57.3% women) who participated in the MIND-China Study in Shandong. Data were collected via face-to-face interviews, clinical examinations, and laboratory tests. RDW was categorized according to quartiles and the lower-extremity physical function was assessed using the Short Physical Performance Battery (SPPB), RESULTS: Multiple linear regression analyses suggested that the fourth quartile of RDW (vs. first quartile) was associated with lower SPPB summary score (β-coefficient - 0.38; 95% CI - 0.58 to - 0.18) and lower scores in balance test (- 0.09; - 0.17 to - 0.01), chair stand test (- 0.17; - 0.27 to - 0.07), and walking speed test (- 0.12; - 0.19 to - 0.05). Anemia was associated with a multiple-adjusted β-coefficient of - 0.34 (- 0.52 to - 0.16) for SPPB summary score. Stratified analysis by anemia showed that there was a linear association between RDW and SPPB in individuals without anemia but a J-shaped association in individuals with anemia.

DISCUSSION

This large-scale population-based study revealed the associations of high RDW and anemia with poor lower-extremity physical function among rural-dwelling Chinese older adults. These findings suggest that an elevated RDW might be a biochemical marker for poor lower-extremity physical function among older adults.

CONCLUSIONS

Anemia and an elevated RDW are associated with poor performance in lower-extremity physical function among rural-dwelling Chinese older adults.

Red Cell Distribution Width and Dementia Among Rural-Dwelling Older Adults: The MIND-China Study

BACKGROUND

Evidence has emerged that anemia is associated with dementia, but data on the relationships of red blood cell distribution width (RDW) with dementia and cognitive function in older adults are sparse.

OBJECTIVE

We sought to investigate the associations of RDW with dementia and global cognitive performance among rural-dwelling Chinese older adults and further to examine their associations by anemia status.

METHODS

This population-based cross-sectional study included 5,115 participants (age≥65 years, 57.0%women) in the baseline examination (March-September 2018) of the Multimodal Interventions to Delay Dementia and Disability in rural China (MIND-CHINA). We collected data through face-to-face interviews, clinical examinations, and laboratory tests. Global cognitive function was evaluated using the Mini-Mental State Examination (MMSE). We defined dementia, Alzheimer's disease (AD), and vascular dementia (VaD) following the respective international criteria. Data were analyzed using multinomial logistic and general linear regression models.

RESULTS

Of all participants, 300 were diagnosed with dementia, including 195 with AD and 95 VaD. The multiple-adjusted odds ratio of dementia associated with quartiles of RDW were 1.45 (95%CI: 0.87-2.44), 1.00 (reference), 1.77 (1.07-2.93), and 2.28 (1.40-3.72). Similar J-shaped patterns existed for the association of RDW with odds ratio of AD and VaD. Anemia was not significantly associated with dementia. The J-shaped associations of RDW with dementia and subtypes were statistically evident only among participants without anemia. There was an inverted J-shaped relationship between RDW quartiles and β-coefficients of MMSE score.

CONCLUSION

There is a J-shaped association between RDW level and likelihood of dementias among rural-dwelling Chinese older adults, especially among people without anemia.