High-sensitivity C-reactive protein and mobility disability in older adults

Inflammatory Biomarkers and Gait Impairment in Older Adults: A Systematic Review

Peripheral inflammation and gait speed alterations are common in several neurological disorders and in the aging process, but the association between the two is not well established. The aim of this systematic literary review is to determine whether proinflammatory markers are a positive predictor for gait impairments and their complications, such as falls in older adults, and may represent a risk factor for slow gait speed and its complications. The systematic review was performed in line with the Preferred Report Items for Systematic Review and Meta-Analyses (PRISMA). A protocol for literature searches was structured a priori and designed according to the International Perspective Register of Systemic Review (PROSPERO: CRD42023451108). Peer-reviewed original articles were identified by searching seven electronic databases: Excerpta Medica Database (EMBASE), SciVerse (ScienceDirect), Scopus, PubMed, Medline, Web of Science, and the Cochrane Library. The search strategy was formulated based on a combination of controlled descriptors and/or keywords related to the topic and a manual search was conducted of the reference lists from the initially selected studies to identify other eligible studies. The studies were thoroughly screened using the following inclusion criteria: older adults, spatiotemporal gait characteristics, and proinflammatory markers. A meta-analysis was not performed due to the heterogeneity of the studies, and the results were narratively synthesized. Due to the clinical and methodological heterogeneity, the studies were combined in a narrative synthesis, grouped by the type of biomarkers evaluated. A standardized data extraction form was used to collect the following methodological outcome variables from each of the included studies: author, year, population, age, sample size, spatiotemporal gait parameters such as gait velocity, and proinflammatory markers such as TNF-α, high sensitivity C-reactive (CRP) proteins, and IL-6. We included 21 out of 51 studies in our review, which examined the association between inflammatory biomarkers and gait impairment. This review highlights the role of TNF-α, CRP, and IL-6 in gait impairment. Biomarkers play an important role in the decision-making process, and IL-6 can be an effective biomarker in establishing the diagnosis of slow gait speed. Further longitudinal research is needed to establish the use of molecular biomarkers in monitoring gait impairment.

Determinants and indicators of successful aging as a multidimensional outcome: a systematic review of longitudinal studies

Background

Successful aging (SA) has been coined as a term to describe the multidimensional aspects associated with achieving optimal combination of physical and mental health along with social well-being health, mental and social well-being at older age. In recent years there has been an increased interest in understanding the role of determinants of SA, such as demographic, biological, behavioral, psychological and social factors. To synthesize the recent evidence, we conducted a systematic review of longitudinal studies on a range of determinants and indicators of SA defined as a multidimensional outcome.

Methods

A systematic search of PubMed, MEDLINE and Web of Science for finding eligible papers published between August 2016 and June 2023 was conducted following the Preferred Reporting Items for a Systematic Review and Meta-Analysis (PRISMA) guidelines. The review protocol was registered in PROSPERO International Prospective Register of Systematic Reviews (Registration number: CRD42021250200). The web-based automated screening tool-Rayyan-was used for title and abstract screening. The study quality was assessed using the Quality in Prognosis Studies (QUIPS) tool.

Results

A total of 3,191 records were initially identified using the predefined search strategy. Out of 289 articles selected for full text screening, 22 were found eligible and included in the review. A variety of factors have been explored in relation to SA, ranging from socio-demographic factors, nutrition, lifestyle, biological pathways, psychological health, and well-being. Overall, the results of recent studies have confirmed the role of metabolic health, adherence to healthy dietary patterns, such as the Mediterranean diet, physical activity, non-smoking, and higher socio-economic status as main factors associated with higher odds for SA. Emerging research highlights the role of psycho-social factors and early life health as determinants of SA.

Conclusion

In summary, this review highlights the importance of healthy living and monitoring metabolic risk along with sustaining psychological well-being in adult life as major determinants of SA. Further methodological and research work on SA would pave the way toward development of adequate health promotion policies in aging societies.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021250200, CRD42021250200.

CRP, but not fibrinogen, is associated with gait speed as early as middle age, in females but not males

Low grade systemic inflammation and age-related gait speed decline are known to be related in older adults, but their relations in the early stages of the aging process are yet to be fully described. The aim of this study was to examine the relationship between gait speed and two inflammation markers-c-reactive protein (CRP) and fibrinogen-in a cohort of middle-aged adults in Israel. 326 healthy, middle-aged, Muslim-Arabs from three villages in northern Israel participated in this cross-sectional study. Serum CRP and fibrinogen were measured via blood tests, and gait speed was assessed with the 6-min walk test (6MWT). After adjusting for sex, age, height, BMI, systolic blood pressure, fasting blood glucose and triglycerides, executive function, smoking status and aerobic physical activity, gait speed was negatively and significantly associated with CRP (b = - 0.01, p = 0.029). When stratifying by gender, this link remained significant only among females (b = - 0.012, p = 0.041), such as that an increase of one SD unit of CRP was associated with a 0.047 m/s decrease in gait speed. No significant link was found between fibrinogen levels and gait speed. Blood CRP levels are associated with a slower walking speed already in middle age, independent of age, executive function and cardio-metabolic factors, among female Arab-Muslims in Israel. Future studies should examine this relationship longitudinally and investigate a broader array of inflammation markers. Systemic inflammation may serve as an early marker for people at risk of decreased walking or accelerated aging; Early identification and intervention among at-risk individuals may help prevent or slow gait speed decline, and promote healthier aging.

Association between levels of high-sensitivity C-reactive protein in plasma and freezing of gait in Parkinson's disease

This study explored the potential relationship between levels of high-sensitivity C-reactive protein (hs-CRP) in plasma and freezing of gait (FOG) in Parkinson's disease (PD) in China. A total of 72 healthy subjects, 62 PD patients with FOG, and 83 PD patients without FOG from our center were enrolled in this prospective study. Patients with FOG showed significantly higher hs-CRP levels than controls, but patients without FOG did not. Binary logistic regression analysis identified levels of hs-CRP in plasma to be an independent risk factor for FOG among the patients in our cohort (OR 6.371, 95% CI 2.589-15.678, p < 0.001). In fact, a cut-off level of 0.935 mg/L distinguished patients with or without FOG [area under the ROC curve (AUC) = 0.908, sensitivity 87.1%, specificity 89.2%]. Our study suggests that high levels of hs-CRP in plasma are associated with the occurrence of FOG in PD. The pooled data combined with a previous study carried out in Spain also indicate a positive association between plasma hs-CRP levels and FOG in PD. However, more research is still needed to verify the plasma hs-CRP as a potential biomarker of FOG.

Physical exercise is associated with a reduction in plasma levels of fractalkine, TGF-β1, eotaxin-1 and IL-6 in younger adults with mobility disability

Mobility disability (MD) refers to substantial limitations in life activities that arise because of movement impairments. Although MD is most prevalent in older individuals, it can also affect younger adults. Increasing evidence suggests that inflammation can drive the development of MD and may need to be targeted for MD prevention. Physical exercise has anti-inflammatory properties and has been associated with MD prevention. However, no studies to date have examined whether exercise interventions affect the peripheral inflammatory status in younger adults with MD. To this end, we used blood samples from young and middle-aged adults with MD (N = 38; median age = 34 years) who participated in a 12-week intervention that included aerobic and resistance exercise training. A pre-post assessment of inflammatory biomarkers was conducted in plasma from two timepoints, i.e., before the exercise trial and at follow-up (3–7 days after the last exercise session). We successfully measured 15 inflammatory biomarkers and found that exercise was associated with a significant reduction in levels of soluble fractalkine, transforming growth factor beta 1 (TGF-β1), eotaxin-1 and interleukin (IL) 6 (corrected α = 0.004). We also found significant male-specific effects of exercise on (i) increasing IL-16 and (ii) decreasing vascular endothelial growth factor-A (VEGF-A). In line with our results, previous studies have also found that exercise can reduce levels of TGF-β1, eotaxin-1 and IL-6. However, our finding that exercise reduces plasma levels of fractalkine in younger adults with MD, as well as the sex-dependent findings, have not been previously reported and warrant replication in larger cohorts. Given the suggested role of inflammation in promoting MD development, our study provides additional support for the use of physical exercise as a treatment modality for MD.

Influences of dopaminergic system dysfunction on late-life depression

Deficits in cognition, reward processing, and motor function are clinical features relevant to both aging and depression. Individuals with late-life depression often show impairment across these domains, all of which are moderated by the functioning of dopaminergic circuits. As dopaminergic function declines with normal aging and increased inflammatory burden, the role of dopamine may be particularly salient for late-life depression. We review the literature examining the role of dopamine in the pathogenesis of depression, as well as how dopamine function changes with aging and is influenced by inflammation. Applying a Research Domain Criteria (RDoC) Initiative perspective, we then review work examining how dopaminergic signaling affects these domains, specifically focusing on Cognitive, Positive Valence, and Sensorimotor Systems. We propose a unified model incorporating the effects of aging and low-grade inflammation on dopaminergic functioning, with a resulting negative effect on cognition, reward processing, and motor function. Interplay between these systems may influence development of a depressive phenotype, with an initial deficit in one domain reinforcing decline in others. This model extends RDoC concepts into late-life depression while also providing opportunities for novel and personalized interventions.

Inflammatory biomarkers and motoric cognitive risk syndrome: Multicohort survey

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Raised IL-6 and CRP levels are associated with increased odds of MCR.

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IL-6 and CRP are involved in overlapping inflammatory, vascular, and neurological pathology.

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Establishing these pathways can guide interventions to prevent progression of MCR to dementia.

Background

Inflammation may play a role in Motoric Cognitive Risk (MCR) syndrome, a pre-dementia syndrome comprised of slow gait and cognitive complaints. Our objective was to examine associations of inflammatory biomarkers with MCR.

Methods

We examined association of interleukin-6 (IL-6) and C-reactive protein (CRP) with prevalent MCR using logistic regression in 3,101 older adults (52% female) from five cohorts (National Center for Geriatrics & Gerontology Study of Geriatric Syndromes [NCGG-SGS], Central Control of Mobility in Aging [CCMA], Tasmanian Study of Cognition and Gait [TASCOG], LonGenity, and Einstein Aging Study [EAS]). Associations were reported as odds ratios adjusted for sex, age, education, depressive symptoms, body mass index, and vascular diseases (aOR) with 95% confidence intervals (CI). Meta-analysis and analyses stratified by vascular disease were also done.

Results

Although associations between higher (worse) CRP and IL-6 tertiles and MCR were only seen in three out of the five cohorts (EAS, TASCOG, and LonGenity), when a pooled meta-analysis was performed, a robust association was demonstrated. In meta-analysis, highest tertiles of IL-6 (aOR 1.57, 95%CI 1.01- 2.44) and CRP (aOR 1.65, 95%CI 1.09–2.48) was associated with MCR versus lowest tertiles in the pooled sample. Higher CRP was associated with MCR among those with vascular disease in TASCOG and LonGenity cohorts, and among those without vascular disease in EAS.

Conclusions

IL-6 and CRP levels are associated with MCR in older adults, and this association varies by presence of vascular disease.

Elevated IL-6 and CRP levels are associated with incident self-reported major mobility disability: A pooled analysis of older adults with slow gait speed

BACKGROUND

Elevated Interleukine-6 (IL-6) and C-reactive protein (CRP) are associated with aging-related reductions in physical function, but little is known about their independent and combined relationships with major mobility disability (MMD), defined as the self-reported inability to walk a quarter-mile.

METHODS

We estimated the absolute and relative effect of elevated baseline IL-6, CRP, and their combination on self-reported MMD risk among older adults (≥68 years; 59% female) with slow gait speed (<1.0m/s). Participants were MMD-free at baseline. IL-6 and CRP were assessed using a central laboratory. The study combined a cohort of community dwelling high-functioning older adults (Health ABC) with two trials of low-functioning adults at risk of MMD (LIFE-P, LIFE). Analyses utilized Poisson regression for absolute MMD incidence and proportional hazards models for relative risk.

RESULTS

We found higher MMD risk per unit increase in log IL-6 [HR=1.26 (95% CI 1.13 to 1.41)]. IL-6 meeting pre-determined threshold considered to be high (>2.5 pg/mL) was similarly associated with higher risk of MMD [HR=1.31 (95% CI: 1.12 to 1.54)]. Elevated CRP (CRP >3.0 mg/L) was also associated with increased MMD risk [HR=1.38 (95% CI: 1.10 to 1.74)]. The CRP effect was more pronounced among participants with elevated IL-6 [HR=1.62 (95% CI: 1.12 to 2.33)] compared to lower IL-6 levels [HR=1.19 (95% CI: 0.85 to 1.66)].

CONCLUSIONS

High baseline IL-6 and CRP were associated with increased risk of MMD among older adults with slow gait speed. A combined biomarker model suggests CRP was associated with MMD when IL-6 was elevated.

Improving gait efficiency to increase movement and physical activity - The impact of abnormal gait patterns and strategies to correct

Increasing daily steps is important to maintain health and prevent both initial and subsequent cardiovascular (CV) disease (CVD) events. Even 5000 steps have been associated with reduced risk of CVD, however many adults and those with CVD walk fewer than 5000 daily steps. Reduced gait speed is a precursor to decreased physical engagement and is associated with biomarker changes linked to higher risk of CVD. Gait speed is decreased in those with CVD, which may be from changes in biomechanics including reduced step length and increased gait variability. Changes in gait and daily steps are often most discernable post-stroke, which may be from limitations of the CV system in meeting the metabolic demands of walking and the nervous system in exciting motoneuron pools to generate muscle force. This leads to gait asymmetries and decreased speed. Information regarding the effects of rehabilitation interventions (e.g., physical therapy) to increase physical activity (PA) in stroke survivors is limited. Current interventions include high intensity gait training and ischemic conditioning to improve walking speed and fatigability. Given the potential benefits of increased PA and daily steps following stroke, there is a need for more research investigating optimal dosage of daily steps and interventions to improve PA.

The Relation of Inflammaging With Skeletal Muscle Properties in Elderly Men

Aging is associated with a progressive decline of muscle mass and/or the qualitative impairment of the muscle tissue. There is growing evidence of the prominent role of low-grade chronic inflammation in age-related changes in the neuromuscular system. The purpose of the study was to identify the inflammatory mediators responsible for deficit in functional fitness and to explain whether inflammation is related to changes in body composition and the decline of muscle strength in older men. Thirty-three old-aged males (73.5 ± 6.3 years) and twenty young-aged males (21.2 ± 1.3 years) participated in the study. The body composition (bioelectrical impedance analysis), functional capacity (6-min walking test) and knee extension strength (isokinetic test) were estimated. In serum, circulating inflammatory markers H₂O₂, IL-1β, TNFα, and hsCRP as well as growth factors IGF-I and PDGF^BB concentrations were determined (immunoenzymatic methods). The concentrations of H₂O₂, IL-1β, TNFα, and hsCRP were significantly higher in older than young men. The growth factors IGF-I and PDGF^BB were twofold lower and related to high levels of IL-1β and TNFα in the elderly. The changes in cytokines and growth factors levels were correlated with age and peak torque (TQ at 60°/s and 180°/s) in the knee extension. The result of the 6-min walking test was inversely correlated with fat mass index (FMI, r = −.983; p < .001). The generation of inflammatory mediators in older men was related to changes in body composition, maximum strength muscle, and age-related changes in skeletal muscle properties responsible for deficit in functional fitness.

Motoric cognitive risk syndrome: Integration of two early harbingers of dementia in older adults

Dementia is characterized by a long preclinical phase that may last years to decades before the onset of mild cognitive impairment. Slow gait speed and subjective memory complaint commonly co-occur during this preclinical phase, and each is a strong independent predictor of cognitive decline and dementia. Motoric cognitive risk (MCR) syndrome is a pre-dementia syndrome that combines these two early harbingers of dementia. The risk of cognitive decline or dementia is stronger for MCR than for either slow gait speed or subjective memory complaint alone. Slow gait speed and subjective memory complaint have several common risk factors: cardiovascular disease, diabetes mellitus, abnormal cortisol profiles, low vitamin D levels, brain atrophy with decreased hippocampal volume, and increased deposition of beta-amyloid in the brain. The underlying pathogenesis of MCR remains poorly understood. Metabolomics and proteomics have great potential to provide new insights into biological pathways involved in MCR during the long preclinical phase preceding dementia.

Longitudinal Relationship Between Interleukin-6 and Perceived Fatigability Among Well-Functioning Adults in Mid-to-Late Life

BACKGROUND

Chronically elevated interleukin-6 (IL-6) levels contribute to fatigue and functional decline via multiple pathways that often lead to frailty. Lesser known is the contribution of IL-6 to fatigue in relation to a standardized workload (fatigability), a precursor to functional decline. Therefore, the purpose of this study was to examine the longitudinal relationship between IL-6 and fatigability.

METHODS

About 985 participants from the Baltimore Longitudinal Study of Aging (mean age: 70 ± 10 years) were evaluated every 1-4 years. IL-6 was measured in fasting serum samples at each visit and log-transformed for analyses. Perceived fatigability (PF) was defined as self-reported exertion (rate of perceived exertion; RPE) after a 5-min, 0.67 m/s, 0% grade treadmill walk. Continuous and categorical associations between IL-6 (baseline and repeated measures) and PF were assessed using generalized estimating equations, adjusting for demographics, behavioral factors, and comorbid conditions.

RESULTS

In fully adjusted continuous models, twofold higher baseline IL-6 was associated with a 0.28 higher RPE (p = .03). This relationship tended to remain constant annually (baseline log IL-6 by time interaction p = .29). To provide clinical relevance, the sample median (3.7 pg/mL) was used to examine high versus low IL-6 levels. Over time, the high group reported an average 0.25 higher RPE (p = .03) than the low group. Annual change in logged IL-6 was not associated with annual change in PF (p = .48).

CONCLUSION

Findings suggest that elevated IL-6 is a biomarker of physiological dysregulation associated with greater fatigability, but there is no longitudinal association between IL-6 and fatigability. Future studies should evaluate whether interventions that aim to reduce inflammation also attenuate fatigability.

Association of 10-Year C-Reactive Protein Trajectories With Markers of Healthy Aging: Findings From the English Longitudinal Study of Aging

Background

Elevated systematic inflammation is a hallmark of aging, but the association of long-term inflammation trajectories with subsequent aging phenotypes has been little examined. We assessed inflammatory marker C-reactive protein (CRP) repeatedly over time and examined whether long-term changes predicted aging outcomes.

Methods

A total of 2,437 men and women aged 47–87 years at baseline (1998–2001) who were participants in the English Longitudinal Study of Ageing had CRP measured on two or three occasions between 1998 and 2009. Inflammation trajectories were computed using latent-class growth mixture modeling and were related to aging outcomes measured in 2012/2013: physical functioning, cardiometabolic, respiratory, mental health, and a composite “healthy aging” outcome.

Results

Four CRP trajectories were identified as follows: “stable-low” (71 per cent of the sample) with baseline mean 1.33 mg/L remaining <3 mg/L; “medium-to-high” (14 per cent) with baseline 2.7 mg/L rising to 5.3 mg/L; “high-to-medium” (10 per cent) with baseline 6.6 mg/L decreasing to 2.4 mg/L; and “stable-high” (5 per cent) with levels from 5.7 to 7.5 mg/L. Relative to the stable-low trajectory, individuals in the medium-to-high had a higher risk of limitations in basic activities of daily living (ADL, odds ratio; 95% confidence interval: 2.09; 1.51, 2.88), instrumental ADL (1.62; 1.15, 2.30), impaired balance (1.59; 1.20, 2.11) and walking speed (1.61; 1.15, 2.24), arthritis (1.55; 1.16, 2.06), hypertension (1.57; 1.21, 2.04), obesity (1.95; 1.36, 2.80), poor respiratory function (1.84; 1.36, 2.50), and depression (1.55; 1.13, 2.12). A lower odds of healthy aging was observed in people in the medium-to-high (0.57; 0.40, 0.79) and stable-high (0.50; 0.27, 0.91) trajectories.

Conclusions

Older people who displayed an elevation in CRP levels over a decade experienced an increased risk of adverse aging outcomes.

High ultrasensitive serum C-reactive protein may be related to freezing of gait in Parkinson's disease patients

C-reactive protein (CRP) is a biomarker of systemic inflammation that has been linked to accelerated decline in walking speed in older adults. The aim of the present study was to compare the CRP levels of PD patients with vs patients without freezing of gait (FOG). Patients and controls participating in the COPPADIS-2015 study that performed blood extraction for determining molecular serum biomarkers were included. Patients with FOG were identified as those with a score of 1 or greater on item-3 of the Freezing of Gait Questionnaire (FOG-Q). Immunoassay was used for determining ultrasensitive CRP (US-CRP) level (mg/dL). In the PD group (n = 225; 61.8 ± 9.5 years old, 61.8% males), 32% of the patients presented FOG but none in the control group (n = 65; 60.3 ± 6.1 years old, 56.9% males) (p < 0.0001). Differences in US-CRP level were significant in patients with FOG vs patients without FOG and vs controls (0.31 ± 0.52 vs 0.16 ± 0.21 vs 0.21 ± 0.22; p = 0.04). Significant differences were also observed between patients with vs without FOG (p = 0.001) but not between patients and controls (p = 0.163). US-CRP level was related to FOG (OR = 4.369; 95% CI 1.105-17.275; p = 0.036) along with H&Y (OR = 2.974; 95% CI 1.113-7.943; p = 0.030) and non-motor symptoms burden (NMSS total score; OR = 1.017; 95% CI 1.005-1.029; p = 0.006) after adjusting for age, gender, disease duration, equivalent daily levodopa dose, number of non-antiparkinsonian drugs per day, motor fluctuations, cognition, motor phenotype, and chronic use of anti-inflammatory drugs. The present study suggests that serum US-CRP level is related to FOG in PD patients. Inflammation could be linked to FOG development.

The urine albumin-creatinine ratio is a predictor for incident long-term care in a general population

Background

Several types of cardiovascular diseases (CVDs) impair the physical and mental status. The purpose of this study was to assess the predictive ability of several cardiovascular biomarkers for identifying the incidence of disability as future recipients of public long-term care (LTC) service.

Methods

The subjects of this study were community-dwelling elderly individuals ≥ 65 years of age without a history of CVD (n = 5,755; mean age, 71 years). The endpoint of this study was official certification as a recipient of LTC. The cohort was divided into quartiles (Qs) based on the levels of three CVD biomarkers: the urinary albumin-creatinine ratio (UACR), plasma B-type natriuretic peptide concentration (BNP), and serum high-sensitivity C-reactive protein concentration (hsCRP). A time-dependent Cox proportional hazard model was used to determine the multi-adjusted relative hazard ratios (HRs) for incident LTC among the quartiles of each biomarker.

Results

During the follow-up (mean 5.6 years), 710 subjects were authorized as recipients of LTC. The HR was only significantly increased in the higher Qs of UACR (Q3, p < 0.01; Q4, p < 0.001). However, other biomarkers were not significantly associated with the endpoint. The risk predictive performance for the incidence of LTC as evaluated by an essential model (i.e. age- and sex-adjusted) was significantly improved by incorporating the UACR (net reclassification improvement = 0.084, p < 0.01; integrated discrimination improvement = 0.0018, p < 0.01).

Conclusions

These results suggest that an increased UACR is useful for predicting physical and cognitive dysfunction in an elderly general population.

Association of Family History of Exceptional Longevity With Decline in Physical Function in Aging

Background

Although many genetic and nongenetic factors interact to determine an individual's physical phenotype, there has been limited examination of the contribution of family history of exceptional parental longevity on decline in physical function in aging.

Methods

The LonGenity study recruited a relatively genetically homogenous cohort of Ashkenazi Jewish adults age 65 and older, who were defined as either offspring of parents with exceptional longevity ([OPEL]: having at least one parent who lived to age 95 or older) or offspring of parents with usual survival ([OPUS]: neither parent survived to age 95). Decline in performance on objective measures of strength (grip strength), balance (unipedal stance), and mobility (gait speed) as well as a composite physical function measure, the Short physical performance battery (SPPB), were compared between the two groups over a median follow-up of 3.2 years, accounting for age, sex, education, and comorbidities.

Results

Of the 984 LonGenity participants (mean age 76, 55% women), 448 were OPEL and 536 were OPUS. Compared to OPUS, OPEL had slower decline on measures of unipedal stance (-0.03 log-units/year, p = .026), repeated chair rise (0.13 s/year, p = .020) and SPPB (-0.11 points/year, p = .002). OPEL women had slower decline on chair rise and SPPB scores compared to OPUS women, although OPEL men had slower decline on unipedal stance compared to OPUS men.

Conclusion

Our findings provide evidence that variation in late-life decline in physical function is associated with familial longevity, and may vary for men and women.

C-reactive protein is associated with disability independently of vascular events: the Northern Manhattan Study

Background

High-sensitivity C-reactive protein (CRP) has been associated with cardiovascular events and mortality, but the association of CRP with functional status is not well defined. We hypothesised that serum levels of high-sensitivity CRP are associated with long-term trajectories of functional status independently of vascular risk factors and stroke and myocardial infarction (MI) occurring during follow-up.

Design

Prospective, population-based.

Setting

Northern Manhattan Study.

Participants

Stroke-free participants aged ≥40 years.

Measurements

Annual assessments of disability with the Barthel index (BI) for a median of 13 years. BI was analysed as a continuous variable (range 0–100). Baseline demographics, risk factors and laboratory studies were collected, including CRP (n = 2,240). Separate generalised estimating equation models estimated standardised associations between CRP and (i) baseline functional status and (ii) change in function over time, adjusting for demographics, vascular risk factors, social variables, cognition, and depression measured at baseline, and stroke and MI occurring during follow-up.

Results

Mean age was 69 (SD 10) years, 36% were male, 55% Hispanic, 75% hypertensive and 21% diabetic; 337 MIs and 369 first strokes occurred during follow-up. Mean CRP level was 5.24 mg/l (SD 8.86). logCRP was associated with baseline BI (−0.34 BI points per unit logCRP, 95% confidence interval −0.62, −0.06) but not with change over time.

Conclusions

In this large population-based study, higher serum CRP levels were associated with higher baseline disability, even when adjusting for baseline covariates and stroke and MI occurring during follow-up. Systemic inflammation may contribute to disability independently of clinical vascular events.

Peripheral brain-derived neurotrophic factor is related to cardiovascular risk factors in active and inactive elderly men

Regular exercise plays an important preventive and therapeutic role in heart and vascular diseases, and beneficially affects brain function. In blood, the effects of exercise appear to be very complex and could include protection of vascular endothelial cells via neurotrophic factors and decreased oxidative stress. The purpose of this study was to identify the age-related changes in peripheral brain-derived neurotrophic factor (BDNF) and its relationship to oxidative damage and conventional cardiovascular disease (CVD) biomarkers, such as atherogenic index, C-reactive protein (hsCRP) and oxidized LDL (oxLDL), in active and inactive men. Seventeen elderly males (61-80 years) and 17 young males (20-24 years) participated in this study. According to the 6-min Åstrand-Rhyming bike test, the subjects were classified into active and inactive groups. The young and elderly active men had a significantly better lipoprotein profile and antioxidant status, as well as reduced oxidative damage and inflammatory state. The active young and elderly men had significantly higher plasma BDNF levels compared to their inactive peers. BDNF was correlated with VO2max (r=0.765, P<0.001). In addition, we observed a significant inverse correlation of BDNF with atherogenic index (TC/HDL), hsCRP and oxLDL. The findings demonstrate that a high level of cardiorespiratory fitness reflected in VO2max was associated with a higher level of circulating BDNF, which in turn was related to common CVD risk factors and oxidative damage markers in young and elderly men.

Associations Between Inflammation and Physical Function in African Americans and European Americans with Prevalent Cardiovascular Risk Factors

OBJECTIVES

To examine associations between inflammation and physical function and potential mediation by white matter hyperintensities (WMHs) in African Americans (AAs) and European Americans (EAs).

DESIGN

Cross-sectional analysis using linear and logistic models with generalized estimating equations to account for family clustering, reporting results as regression coefficients (β) and odds ratios (ORs) adjusted for education, alcohol, exercise, body mass index, hypertension, diabetes mellitus, heart disease, cognition, ankle-brachial index, race (site), and supported interactions.

SETTING

Genetic Epidemiology Network of Arteriopathy-Genetics of Microangiopathic Brain Injury Study cohort.

PARTICIPANTS

AA and EA sibships with two or more siblings with hypertension before age 60 (N = 1,960; 65% female, 51% AA, aged 26-91, 50% obese, 72% hypertensive).

MEASUREMENTS

Inflammation (C-reactive protein (CRP), interleukin-6 (IL6), soluble tumor necrosis factor receptors (sTNFRs) 1 and 2, WMH volume (cm(3) ) according to magnetic resonance imaging), walking speed (cm/s) over 25 feet, and mobility difficulty (any self-reported difficulty walking half a mile).

RESULTS

In separate models, inflammatory markers were associated with walking speed (sTNFR1: β = -2.74, P < .001; sTNFR2: β = -1.23, P = .03; CRP: β = -1.95, P = .001; IL6: β = -1.24, P = .03) and mobility difficulty (sTNFR1: OR = 1.36, P = .001; sTNFR2: OR = 1.25, P = .005; CRP: OR = 1.22, P = .005; IL6: OR = 1.18, P = .02); the association between WMH volume and sTNFR1 in AA (β = 0.07, P = .06) did not reach typical statistical thresholds. WMH volume was associated with walking speed in AA (β = -3.17, P = .02) but not with mobility difficulty (OR = 1.10, P = .54). Adjusting for WMH did not change associations.

CONCLUSION

In young, middle-aged, and older adults with prevalent cardiovascular risk factors, multiple inflammatory biomarkers were associated with slower walking speed independent of microvascular disease in the brain. There was little evidence of mediation by brain WMH volume. Inflammation may contribute to physical function impairments through pathways other than brain microvascular disease, particularly in AAs.

Increased follistatin associated with decreased gait speed among old adults

BACKGROUND

Low gait speed is associated with inflammation and muscle strength. Follistatin, a glycosylated plasma protein, is involved in inflammatory diseases, bone metabolism, muscle strength and cognition. However, research regarding the relationship between follistatin and gait speed in elderly individuals is limited. In this study, we aimed to examine the association between follistatin and gait speed in older adults.

METHODS

This cross-sectional, observational study included 205 ambulatory individuals aged ≥ 65 years. The baseline measures included 15-foot walking time, a structured questionnaire, grip strength and biomarkers, including follistatin and myostatin levels. Multiple linear regression was used to determine the change in gait speed for each 1 pg/mL increase in serum follistatin level. An extended model approach with a quartile-based analysis of serum follistatin levels was conducted.

RESULTS

In the linear regression model, the β coefficient, representing the change in gait speed for each 1 pg/mL increase in serum follistatin level, was -0·308 (P < 0·001). After additional adjustment for relevant covariates, the β coefficient changed slightly, although the negative correlation remained (all P ≤ 0·001). After controlling for multiple covariates, participants in the highest serum follistatin level quartile had a significantly lower gait speed than those in the lowest quartile (all P for trend < 0·001).

CONCLUSIONS

A higher follistatin level was independently associated with lower gait speed in community-dwelling elderly individuals; this suggests that serum follistatin level may be an indicator of mobility in elderly persons and may more particularly represent lower extremity function.

Biomarkers of oxidative stress are associated with frailty: the Framingham Offspring Study

Cardiovascular disease and frailty frequently occur together. Both are associated with inflammation, which may be partially triggered by oxidative stress, especially in cardiovascular disease. We investigated whether inflammatory and oxidative stress biomarkers linked to cardiovascular disease were associated with frailty and the related outcome of gait speed. We report cross-sectional associations of biomarkers and frailty assessed at Framingham Offspring Study cycle eight. Participants ≥60 years were eligible if they had information on frailty and at least one of the following: C-reactive protein, interleukin-6, tumor necrosis factor receptor 2, 8-epi-FGFα isoprostanes (isoprostanes), lipoprotein phospholipase A2 (LpPLA2) mass or activity, osteoprotegerin, intracellular adhesion molecule-1, monocyte chemoattractant protein-1 or P-selectin. Stepwise logistic models were utilized for frailty and stepwise linear models for gait speed. Covariates included age, sex, body mass index, smoking, and co-morbidities. Odds ratios (ORs) and slope estimates (B) are reported per standard deviation increase of loge-transformed biomarker. Of the 1919 participants, 142 (7 %) were frail. In a stepwise model, frailty odds increased with higher interleukin-6 (OR 1.90, 95 % CI 1.51, 2.38), isoprostanes (OR 1.46, 95 % CI 1.12, 1.92), and LpPLA2 mass (OR 1.29, 95 % CI 1.00, 1.65). Stepwise regression found that slower gait speeds were associated with interleukin-6 (B = -0.025 m/s, 95 % CI 0.04, -0.01), isoprostanes (B = -0.019, 95 % CI -0.03, -0.008), LpPLA2 mass (B = -0.016, 95 % CI -0.03, -0.004), and osteoprotegerin (B = -0.015, 95 % CI -0.03, -0.002, all p < 0.05). Interleukin-6, isoprostanes, and LpPLA2 mass were associated with greater frailty odds and slower gait speeds. Oxidative stress may be a mechanism contributing to frailty.

Successful aging: Advancing the science of physical independence in older adults

The concept of 'successful aging' has long intrigued the scientific community. Despite this long-standing interest, a consensus definition has proven to be a difficult task, due to the inherent challenge involved in defining such a complex, multi-dimensional phenomenon. The lack of a clear set of defining characteristics for the construct of successful aging has made comparison of findings across studies difficult and has limited advances in aging research. A consensus on markers of successful aging is furthest developed is the domain of physical functioning. For example, walking speed appears to be an excellent surrogate marker of overall health and predicts the maintenance of physical independence, a cornerstone of successful aging. The purpose of the present article is to provide an overview and discussion of specific health conditions, behavioral factors, and biological mechanisms that mark declining mobility and physical function and promising interventions to counter these effects. With life expectancy continuing to increase in the United States and developed countries throughout the world, there is an increasing public health focus on the maintenance of physical independence among all older adults.

Younger subjective age is associated with lower C-reactive protein among older adults

Subjective age, or how young or old individuals experience themselves to be, is related to a range of health-related outcomes in old age, including mortality risk. Little is known, however, about its association with markers of systemic inflammation. Using data from the Health and Retirement Study (HRS), the present study examined the relation between subjective age and C-reactive protein (CRP). Participants were 4120 older adults from the 2008 wave of the HRS who provided measures of subjective age, CRP, demographic variables, Body Mass Index (BMI), depression, smoking, physical activity and disease burden. Regression analyses revealed that a younger subjective age was related to lower CRP, controlling for demographic factors. This association was reduced by half but remained significant when health and behavioral covariates were adjusted for, suggesting that BMI, physical activity and disease burden may partially account for lower inflammation in individuals with a younger subjective age. Furthermore, a logistic regression revealed that feeling younger than one's age was associated with reduced risk of exceeding the clinical threshold of CRP, controlling for covariates. The present study provides the first evidence of an association between subjective age and systemic inflammation among older adults. It suggests that individuals' ratings of their subjective age may help identify individuals at greater risk for immune dysfunction related to morbidity and mortality.

Obesity-related inflammation: implications for older adults

The combination of age-related increases in obesity and inflammation can lead to chronic disease, decreased strength, and physical disability. Lifestyle interventions that include moderate caloric restriction along with aerobic and resistance exercise have shown improvements in metabolic outcomes, strength, and physical function in obese older adults. Although few weight loss studies have addressed diet quality, evidence summarized in this review suggests that encouraging intake of antioxidant-rich fruits and vegetables, high-quality protein, low-glycemic index carbohydrates, and omega-3 fatty acids may further ameliorate obesity-related inflammation. Future controlled trials are indicated to examine the effects of incorporating these foods into multimodal weight loss interventions.

C-reactive protein, vitamin D deficiency, and slow gait speed

OBJECTIVES

To evaluate the independent and joint effects of C-reactive protein (CRP) and 25-OH vitamin D (25(OH)D) levels on mobility disability in older persons.

DESIGN

U.S. population-based cross-sectional study.

SETTING

National Health and Nutrition Examination Surveys (2001-2002).

PARTICIPANTS

Individuals aged 50 and older (N = 1,826).

MEASUREMENTS

C-reactive protein (mg/dL), with high CRP defined as ≥ 0.2 mg/dL, and 25(OH)D levels (ng/mL) operationalized as severe deficiency (<10 ng/mL), deficiency (10-19.9 ng/mL), insufficiency (20-29.9 ng/mL), and normal (≥ 30 ng/mL). Mobility disability was operationalized as gait speed of <0.8 m/s while completing a 20-foot walk (6.1 m).

RESULTS

High CRP and low 25(OH)D levels were associated with slow gait speed. Individuals with high CRP levels and severe vitamin D deficiency were more likely to have slow gait speed than were those with neither risk factor (odds ratio = 3.54, 95% confidence interval = 1.42-8.84, P = .007). A significant positive association between vitamin D level and gait speed was found only in those with high CRP in stratified analyses. Whites and blacks showed similar findings as the overall population.

CONCLUSION

These findings provide evidence of a potential joint effect of vitamin D and CRP on gait speed, suggesting that evaluation and correction of vitamin D levels may be especially important in individuals with high CRP levels.