Epigenetic signature of human immune aging in the GESTALT study

Age-associated DNA methylation in blood cells convey information on health status. However, the mechanisms that drive these changes in circulating cells and their relationships to gene regulation are unknown. We identified age-associated DNA methylation sites in six purified blood-borne immune cell types (naive B, naive CD4+ and CD8+ T cells, granulocytes, monocytes, and NK cells) collected from healthy individuals interspersed over a wide age range. Of the thousands of age-associated sites, only 350 sites were differentially methylated in the same direction in all cell types and validated in an independent longitudinal cohort. Genes close to age-associated hypomethylated sites were enriched for collagen biosynthesis and complement cascade pathways, while genes close to hypermethylated sites mapped to neuronal pathways. In silico analyses showed that in most cell types, the age-associated hypo- and hypermethylated sites were enriched for ARNT (HIF1β) and REST transcription factor (TF) motifs, respectively, which are both master regulators of hypoxia response. To conclude, despite spatial heterogeneity, there is a commonality in the putative regulatory role with respect to TF motifs and histone modifications at and around these sites. These features suggest that DNA methylation changes in healthy aging may be adaptive responses to fluctuations of oxygen availability.

Plasma metabolomic signatures of dual decline in memory and gait in older adults

Older adults experiencing dual decline in memory and gait have greater dementia risk than those with memory or gait decline only, but mechanisms are unknown. Dual decline may indicate specific pathophysiological pathways to dementia which can be reflected by circulating metabolites. We compared longitudinal changes in plasma metabolite biomarkers of older adults with and without dual decline in the Baltimore Longitudinal Study of Aging (BLSA). Participants were grouped into 4 phenotypes based on annual rates of decline in verbal memory and gait speed: no decline in memory or gait, memory decline only, gait decline only, and dual decline. Repeated measures of plasma metabolomics were measured by biocrates p500 kit during the same time of memory and gait assessments. In BLSA, 18 metabolites differed across groups (q-value < 0.05). Metabolites differentially abundant were enriched for lysophosphatidylcholines (lysoPC C18:0,C16:0,C17:0,C18:1,C18:2), ceramides (d18:2/24:0,d16:1/24:0,d16:1/23:0), and amino acids (glycine) classes. Compared to no decline, the dual decline group showed greater declines in lysoPC C18:0, homoarginine synthesis, and the metabolite module containing mostly triglycerides, and showed a greater increase in indoleamine 2,3-dioxygenase (IDO) activity. Metabolites distinguishing dual decline and no decline groups were implicated in metabolic pathways of the aminoacyl-tRNA biosynthesis, valine, leucine and isoleucine biosynthesis, histidine metabolism, and sphingolipid metabolism. Older adults with dual decline exhibit the most extensive alterations in metabolic profiling of lysoPCs, ceramides, IDO activity, and homoarginine synthesis. Alterations in these metabolites may indicate mitochondrial dysfunction, compromised immunity, and elevated burden of cardiovascular and kidney pathology.

A Gentle Introduction to Bayesian Network Meta-Analysis Using an Automated R Package

Network meta-analysis is an extension of standard meta-analysis. It allows researchers to build a network of evidence to compare multiple interventions that may have not been compared directly in existing publications. With a Bayesian approach, network meta-analysis can be used to obtain a posterior probability distribution of all the relative treatment effects, which allows for the estimation of relative treatment effects to quantify the uncertainty of parameter estimates, and to rank all the treatments in the network. Ranking treatments using both direct and indirect evidence can provide guidance to policy makers and clinicians for making decisions. The purpose of this paper is to introduce fundamental concepts of Bayesian network meta-analysis (BNMA) to researchers in psychology and social sciences. We discuss several essential concepts of BNMA, including the assumptions of homogeneity and consistency, the fixed and random effects models, prior specification, and model fit evaluation strategies, while pointing out some issues and areas where researchers should use caution in the application of BNMA. Additionally, using an automated R package, we provide a step-by-step demonstration on how to conduct and report the findings of BNMA with a real dataset of psychological interventions extracted from PubMed.

DNA methylation GrimAge version 2

We previously described a DNA methylation (DNAm) based biomarker of human mortality risk DNAm GrimAge. Here we describe version 2 of GrimAge (trained on individuals aged between 40 and 92) which leverages two new DNAm based estimators of (log transformed) plasma proteins: high sensitivity C-reactive protein (logCRP) and hemoglobin A1C (logA1C). We evaluate GrimAge2 in 13,399 blood samples across nine study cohorts. After adjustment for age and sex, GrimAge2 outperforms GrimAge in predicting mortality across multiple racial/ethnic groups (meta P=3.6x10^-167 versus P=2.6x10^-144) and in terms of associations with age related conditions such as coronary heart disease, lung function measurement FEV1 (correlation= -0.31, P=1.1x10^-136), computed tomography based measurements of fatty liver disease. We present evidence that GrimAge version 2 also applies to younger individuals and to saliva samples where it tracks markers of metabolic syndrome. DNAm logCRP is positively correlated with morbidity count (P=1.3x10^-54). DNAm logA1C is highly associated with type 2 diabetes (P=5.8x10^-155). DNAm PAI-1 outperforms the other age-adjusted DNAm biomarkers including GrimAge2 in correlating with triglyceride (cor=0.34, P=9.6x10^-267) and visceral fat (cor=0.41, P=4.7x10^-41). Overall, we demonstrate that GrimAge version 2 is an attractive epigenetic biomarker of human mortality and morbidity risk.

Association between walking energy utilisation and longitudinal cognitive performance in older adults

BACKGROUND

Human motor function is optimised for energetic efficiency, however, age-related neurodegenerative changes affects neuromotor control of walking. Energy utilisation has been associated with motor performance, but its association with cognitive performance is unknown.

METHODS

The study population included 979 Baltimore Longitudinal Study of Aging participants aged $\ge$50 years (52% female, mean age: 70$\pm$10.2 years) with a median follow-up time of 4.7 years. Energy utilisation for walking was operationalised as a ratio of the energy cost of slow walking to peak walking energy expenditure during standardised tasks ('cost-ratio'). Cognitive functioning was measured using the Trail Making Tests, California Verbal Learning Test, Wechsler Adult Intelligence Scale (WAIS), letter and category fluency and card rotation tests. Linear mixed models adjusted for demographics, education and co-morbidities assessed the association between baseline cost-ratio and cognitive functioning, cross-sectionally and longitudinally. To investigate the relationship among those with less efficient energy utilisation, subgroup analyses were performed.

RESULTS

In fully adjusted models, a higher cost-ratio was cross-sectionally associated with poorer performance on all cognitive tests except WAIS (P < 0.05 for all). Among those with compromised energy utilisation, the baseline cost-ratio was also associated with a faster decline in memory (long-delay free recall: β = -0.4, 95% confidence interval [CI] = [-0.8, -0.02]; immediate word recall: β = -1.3, 95% CI = [-2.7, 0.1]).

CONCLUSIONS

These findings suggest cross-sectional and longitudinal links between energy utilisation and cognitive performance, highlighting an intriguing link between brain function and the energy needed for ambulation. Future research should examine this association earlier in the life course to gauge the potential for interventive mechanisms.

Disparities in place of death from prostate cancer revealed by disaggregation of Asian race

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Background: Place of death (PoD) is a surrogate determinant of health care inequity in patients with cancer. Aggregation of Asian Americans, a diverse group, may mask significant health disparities in end-of-life care. Methods: De-identified death certificate data were obtained via the National Center for Health Statistics. All adult (> 18 years of age) prostate cancer deaths from 2018 to 2019 were included. Multinomial logistic regression was used to test for differences in place of death associated with sociodemographic variables. Results: From 2018 through 2019, 81,292 adults died from prostate cancer. Overall, most Asians were less likely to die at home (p < 0.05) or nursing facility (p < 0.05) compared to White patients. Significant differences in nursing facility use was noted in disaggregated analysis, with Samoan patients 12.44 times more likely to die in a hospice facility compared to hospital (CI 2.89, 53.6; p < 0.001) and Chinese patients 100 times less likely to die in a hospice facility (CI 0.01, 0.02; p < 0.001) to give two notable examples. Chinese (OR 0.26), Guamanian (OR 0.2), and Vietnamese race (OR 0.05) had the lowest likelihood of dying at home, with odds ratio lower than Black race (OR 0.3) (Table). Conclusions: Increased attention to PoD over recent years has highlighted issues around equity in end-of-life care. Overall, our data underscore important differences among Asian subpopulations and possible barriers to quality end of life care that would otherwise be masked with data aggregation. It is well known that resources are needed to allow death at home or at a nursing facility. Further qualitative work is planned to investigate culture differences contributing to PoD differences for patients with cancer through the lens of the social determinants of health.

A computational solution for bolstering reliability of epigenetic clocks: Implications for clinical trials and longitudinal tracking

Epigenetic clocks are widely used aging biomarkers calculated from DNA methylation data, but this data can be surprisingly unreliable. Here we show technical noise produces deviations up to 9 years between replicates for six prominent epigenetic clocks, limiting their utility. We present a computational solution to bolster reliability, calculating principal components from CpG-level data as input for biological age prediction. Our retrained principal-component versions of six clocks show agreement between most replicates within 1.5 years, improved detection of clock associations and intervention effects, and reliable longitudinal trajectories in vivo and in vitro. This method entails only one additional step compared to traditional clocks, requires no replicates or prior knowledge of CpG reliabilities for training, and can be applied to any existing or future epigenetic biomarker. The high reliability of principal component-based clocks is critical for applications to personalized medicine, longitudinal tracking, in vitro studies, and clinical trials of aging interventions.

Epigenetic Age Acceleration and Hearing: Observations From the Baltimore Longitudinal Study of Aging

Objectives: Age-related hearing loss (ARHL) is highly prevalent among older adults, but the potential mechanisms and predictive markers for ARHL are lacking. Epigenetic age acceleration has been shown to be predictive of many age-associated diseases and mortality. However, the association between epigenetic age acceleration and hearing remains unknown. Our study aims to investigate the relationship between epigenetic age acceleration and audiometric hearing in the Baltimore Longitudinal Study of Aging (BLSA).

Methods: Participants with both DNA methylation and audiometric hearing measurements were included. The main independent variables are epigenetic age acceleration measures, including intrinsic epigenetic age acceleration—“IEAA,” Hannum age acceleration—“AgeAccelerationResidualHannum,” PhenoAge acceleration—“AgeAccelPheno,” GrimAge acceleration—“AgeAccelGrim,” and methylation-based pace of aging estimation—“DunedinPoAm.” The main dependent variable is speech-frequency pure tone average. Linear regression was used to assess the association between epigenetic age acceleration and hearing.

Results: Among the 236 participants (52.5% female), after adjusting for age, sex, race, time difference between measurements, cardiovascular factors, and smoking history, the effect sizes were 0.11 995% CI: (–0.00, 0.23), p = 0.054] for Hannum’s clock, 0.08 [95% CI: (–0.03, 0.19), p = 0.143] for Horvath’s clock, 0.10 [95% CI: (–0.01, 0.21), p = 0.089] for PhenoAge, 0.20 [95% CI: (0.06, 0.33), p = 0.004] for GrimAge, and 0.21 [95% CI: (0.09, 0.33), p = 0.001] for DunedinPoAm.

Discussion: The present study suggests that some epigenetic age acceleration measurements are associated with hearing. Future research is needed to study the potential subclinical cardiovascular causes of hearing and to investigate the longitudinal relationship between DNA methylation and hearing.

Understanding the Human Aging Proteome Using Epidemiological Models

Human aging is a complex multifactorial process associated with a decline of physical and cognitive function and high susceptibility to chronic diseases, influenced by genetic, epigenetic, environmental, and demographic factors. This chapter will provide an overview on the use of epidemiological models with proteomics data as a method that can be used to identify factors that modulate the aging process in humans. This is demonstrated with proteomics data from human plasma and skeletal muscle, where the combination with epidemiological models identified a set of mitochondrial, spliceosome, and senescence proteins as well as the role of energetic pathways such as glycolysis, and electron transport pathways that regulate the aging process.

Prevalence of Concurrent Functional Vision and Hearing Impairment and Its Association with Dementia

Vision and hearing impairment are common and independently linked to dementia risk. Adults with concurrent vision and hearing impairment (dual sensory impairment, DSI) may be particularly at-risk. Data were from the National Health and Aging Trends Study (NHATS) (2011–2018, N=7,562). Functional sensory impairments were self-reported (no impairment, vision only, hearing only, and DSI). We calculated age-specific prevalence of sensory impairments. Discrete time proportional hazards model with a complementary log-log link were used to assess 7-year dementia risk. Of 7,562 participants, overall prevalence of functional vision, hearing and DSI was 5.4%, 18.9% and 3.1%, respectively. DSI prevalence increased with age, impacting 1 in 7 adults ≥90 years. DSI was associated with a 50% increased 7-year dementia risk (adjusted hazard ratio 1.50; 95% confidence interval, 1.12–2.02) compared to no impairment. Sensory rehabilitative interventions for multiple impairments may be an avenue for consideration in efforts to reduce dementia risk.

Longitudinal Profiling in Phenotypic Metric of Aging: Insights From the Baltimore Longitudinal Study of Aging

It remains challenging to quantify the pace of aging across lifespan due to lack of comprehensive longitudinal measurements across wide range of age. In Baltimore Longitudinal Study of Aging, we have measured the longitudinal trajectories of more than 30 phenotypes across four pre-identified domain - body composition, energy regulation, homeostatic mechanisms and neurodegeneration/neuroplasticity, among participants with age between 20+ and 90+. We implemented a two-stage approach to summarize the longitudinal trajectories of these phenotypes across four domains into a summarized score. We demonstrated that higher summarized score (denoting for slower longitudinal phenotypic decline) is associated with slower decline in both cognitive and physical functions, across different stages of adulthood. Our results imply that deep longitudinal profiling contains rich information and may potentially replace diseases as an early endpoint in trials targeting at aging. Further, understanding the underpinning of longitudinal phenotypic trajectories may provide clues to the biological mechanisms of aging.

Fatigability: An Early Marker of Diminished Renal Function?

Renal function declines markedly with age due to normal aging and/or disease processes and impacts multiple systems. Diminished renal function may manifest as low exercise tolerance and fatigue threshold. Using data on 951 well-functioning (usual gait speed &gt;.67m/s and no difficulty walking ¼ mile) men and women (51%) aged 60-89 years in the Baltimore Longitudinal Study of Aging, we evaluated the cross-sectional association between perceived fatigability (Rating Perceived Exertion after 5-minute treadmill walk at 1.5mph) categorized as 6-7, 8-9, 10-11 and 12+ and GFR using Cockcroft-Gault. For each fatigability increment, likelihood of suboptimal (GFR=75-89, 21%), diminished (GFR=60-74, 26%) and poor renal function (GFR=15-59, 30%) relative to GFR≥90 was respectively OR(95%CI)p-value 1.51(1.16-1.96).002, 1.38(1.04-1.83).027 and 1.68(1.22-2.31).002 adjusted for demographics, weight, height, smoking, exercise and anemia. Findings were similar for men and women. Perceived fatigability may facilitate identification of apparently well-functioning older adults on the precipice of suboptimal to poor renal function.

Activity Fractionation Moderates the Relationship of Gait Speed With Alzheimer’s Disease Risk

Older adults with slow gait have a modestly elevated risk of Alzheimer’s disease (AD). Whether strategies to maintain function, such as interlacing periods of activity and rest, modify this relationship is unknown. We analyzed 577 initially cognitively normal participants aged 50+(53%women,26%Black) who had baseline data on gait speed and fractionation via ActiHeart. Diagnoses of mild cognitive impairment (MCI)/AD were adjudicated during an average 7.3years follow-up. We examined gait speed, fractionation, and their interaction with MCI/AD risk using Cox proportional-hazards models, adjusted for demographics and APOE-e4. Each 0.2m/sec faster gait speed was associated with 24% lower risk of MCI/AD(p=0.04). Fractionation was not associated with MCI/AD risk(p>0.05). There was a significant gait*fractionation interaction(p=0.013). At high fractionation, gait was not predictive of MCI/AD. Slow gait speed is less predictive of future MCI/AD in individuals who fractionate their activity to maintain function, possibly indicating brain function that drives such compensatory strategy is still conserved.

Association of Hearing Impairment With Higher Level Physical Functioning and Walking Endurance

The longitudinal associations between hearing impairment and higher-level functional measures and the potential confounding role of vestibular function have not been assessed. We investigated these associations in 831 participants of the Baltimore Longitudinal Study of Aging (2012–2019). Hearing was measured using pure-tone audiometry and categorized using WHO standards. Physical function was assessed with the Health Aging and Body Composition Physical Performance Battery (HABCPPB, higher=better) and walking endurance with time to walk 400 meters. Multivariable regression models tested the hypotheses that participants with hearing impairment have poorer physical outomes. In a subset, we further adjusted for vestibular function. Hearing impairment was associated with decrements in higher-level physical performance and walking endurance, and faster decline over time, regardless of vestibular function. Among participants with any hearing impairment, hearing aid users were faster in the 400-m walk. Early screening for higher-level functional loss among older adults with hearing loss is warranted.

Links of Sleep Duration with Biomarkers of Accelerated Aging: the Baltimore Longitudinal Study of Aging

Sleep disorders and sleep deprivation have been linked to markers of biological aging, including methylation change and increases in white blood cell and neutrophil counts. However, little is known regarding the association of sleep duration with biological markers of aging. We investigated links of self-reported sleep duration with biological aging markers in 615 participants in the Baltimore Longitudinal Study of Aging (BLSA) aged ≥50 years (mean = 71.0 ± 11.2, 49.6% women, 68.8% white) with data on self-reported sleep duration in hours (i.e., ≤6 (n=131), &gt;6 to 7 (n=234), &gt;7 (n=250)), demographics, and genetic and methylation data (mDNA). Our aging biomarker outcomes were four epigenetic clocks (Horvath, Hannum, PhenoAge, and GrimAge), mDNA-estimated PAI1, and estimated granulocyte count. After adjustment for age, sex, and race, compared to those sleeping ≤6 hours, those reporting &gt;7 hours of sleep had faster biological aging according to Hannum age-acceleration, PhenoAge, GrimAge, mDNA-estimated PAI1, and granulocyte count. In addition, sleep duration interacted with age, such that compared to individuals reporting ≤6 hours of sleep, individuals reporting &gt;6 to 7 hours showed lower GrimAge with increasing age, and with sex, such that males with longer sleep duration (&gt;6 to 7 and &gt;7 hours) showed a lower granulocyte count compared to females. Findings suggest that both short and long sleep duration are associated with and may contribute to accelerated aging. Prospective studies in larger samples are needed to examine whether changes in sleep duration precede changes in aging biomarkers.

Longitudinal trajectories and determinants of human fungiform papillae density

Tongue fungiform papillae contain taste buds crucial for taste and hormone-producing taste receptor cells; therefore, they may be considered as endocrine organs and have important age-associated physiological implications. We examine the cross-sectional and longitudinal trajectories of fungiform papillae density in 1084 participants from the Baltimore Longitudinal Study of Aging using linear regression models and mixed effects models. At baseline, the mean age was 67.86 ± 14.20 years, with a mean follow-up time among those with repeat visits of 4.24 ± 1.70 years. Women (53%) were younger (66.85 ± 13.78 vs. 69.04 ± 14.61 years, p < 0.001) and had a higher fungiform papillae density than men (16.14 ± 9.54 vs. 13.77 ± 8.61 papillae/cm², p < 0.001). Whites (67%) had a lower fungiform papillae density than non-Whites after adjusting for age and sex. Factors cross-sectionally associated with a lower fungiform papillae density included a higher waist-hip ratio (β = −8.525, p = 0.029), current smoking status (β = −5.133, p = 0.014), and alcohol use within the past 12 months (β = −1.571, p = 0.025). Longitudinally, fungiform papillae density decreased linearly with follow-up time (β = −0.646, p < 0.001). The rate of decline was not affected by sex, race, BMI, waist-hip ratio, smoking, or alcohol use. The longitudinal decline of fungiform papillae density over time needs to be explored further in order to identify other possible age-associated physiological determinants.

The Relationship of APOE ε4, Race, and Sex on the Age of Onset and Risk of Dementia

Objective: To investigate whether APOE ε4 genotype—an established risk factor for dementia—is associated with earlier age at diagnosis in addition to increased risk overall and in secondary analysis by race and sex.

Methods: We followed up 13,782 dementia-free individuals (n = 10,137 White, n = 3,645 Black, baseline age 60–66 years) in the Atherosclerosis Risk in Communities study for up to 30 years. Dementia was operationalized using standardized algorithms incorporating longitudinal cognitive change, proxy report, and hospital or death certificate dementia codes. We used a mixture of generalized gamma distributions to simultaneously estimate time to dementia, time to dementia-free death, and the proportion of individuals with dementia, by APOE ε4 status (≥1 vs. no alleles).

Results: Median age of dementia onset among APOE ε4 carriers was 81.7 (Blacks) and 83.3 years (Whites) compared with 82.6 (Blacks) and 85.7 years (Whites) in non-APOE ε4 carriers (p > 0.05 Blacks; p < 0.01 Whites). Age of dementia diagnosis did not differ by sex in ε4 carriers, but among non-carriers, average age was earlier in males than females regardless of race. APOE ε4 carriers had on average a higher proportion of diagnoses; results did not differ by race or sex.

Conclusions:APOE ε4 carrier status is associated with earlier age of dementia diagnosis with differences across race and sex. These findings clarify the causal role of APOE in dementia etiology, which could help better identify at-risk subgroups and may help facilitate better research trial recruitment and design.

Association of Combined Slow Gait and Low Activity Fragmentation With Later Onset of Cognitive Impairment

IMPORTANCE

Among older people, slow walking is an early indicator of risk for Alzheimer disease (AD). However, studies that have assessed this association have not considered that slow walking may have different causes, some of which are not necessarily associated with higher AD risk.

OBJECTIVE

To evaluate whether low activity fragmentation among older adults with slow gait speed indicates neurological causes of slow walking that put these individuals at higher risk of AD.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study performed survival analyses using data from the Baltimore Longitudinal Study of Aging. Participants included 520 initially cognitively normal persons aged 60 years or older. New diagnoses of mild cognitive impairment (MCI) or AD were adjudicated during a mean (SD) follow-up of 7.3 (2.7) years. Initial assessment of gait speed and activity fragmentation occurred from January 3, 2007, to May 11, 2015, with follow-up completed on December 31, 2020. Data were analyzed from February 1 to May 15, 2021.

EXPOSURES

Gait speed for 6 m and activity fragmentation assessed by accelerometry.

MAIN OUTCOMES AND MEASURES

Associations of gait speed, activity fragmentation, and their interaction with incident MCI/AD were evaluated using Cox proportional hazards models, adjusted for covariates.

RESULTS

Among the 520 participants (265 women [51.0%]; 125 Black participants [24.0%]; 367 White participants [70.6%]; mean [SD] age, 73 [8] years), MCI/AD developed in 64 participants. Each 0.05-m/s slower gait was associated with a 7% increase in risk of developing MCI/AD (hazard ratio [HR], 1.07 [95% CI, 1.00-1.15]; P = .04). Activity fragmentation alone was not associated with MCI/AD risk (HR, 0.83 [95% CI, 0.56-1.23]; P = .35), but there was a significant interaction between gait speed and activity fragmentation (HR, 0.92 [95% CI, 0.87-0.98]; P = .01). At low activity fragmentation (-1 SD), each 0.05-m/s slower gait speed was associated with a 19% increase in hazard of developing MCI/AD (HR, 1.19 [95% CI, 1.07-1.32]), whereas at higher activity fragmentation (+1 SD), gait speed was not associated with MCI/AD (HR, 1.01 [95% CI, 0.93-1.10]). Among participants with slow gait, higher activity fragmentation was associated with higher odds of having lower extremity osteoarthritis (odds ratio, 1.31 [95% CI, 1.01-1.69]) and less decline in pegboard dominant hand performance (β = 0.026 [SE, 0.009]; P > .05).

CONCLUSIONS AND RELEVANCE

These findings suggest that frequent rests among older adults with slow gait speed are associated with lower risk of future MCI/AD and that this behavioral strategy is associated with a lower likelihood of subclinical neurological impairment.

Functional stability of CFTR depends on tight binding of ATP at its degenerate ATP-binding site

Opening of the cystic fibrosis transmembrane conductance regulator (CFTR) channel is coupled to the motion of its two nucleotide-binding domains: they form a heterodimer sandwiching two functionally distinct ATP-binding sites (sites 1 and 2). While active ATP hydrolysis in site 2 triggers rapid channel closure, the functional role of stable ATP binding in the catalysis-incompetent (or degenerate) site 1, a feature conserved in many other ATP-binding cassette (ABC) transporter proteins, remains elusive. Here, we found that CFTR loses its prompt responsiveness to ATP after the channel is devoid of ATP for tens to hundreds of seconds. Mutants with weakened ATP binding in site 1 and the most prevalent disease-causing mutation, F508del, are more vulnerable to ATP depletion. In contrast, strengthening ligand binding in site 1 with N⁶ -(2-phenylethyl)-ATP, a high-affinity ATP analogue, or abolishing ATP hydrolysis in site 2 by the mutation D1370N, helps sustain a durable function of the otherwise unstable mutant channels. Thus, tight binding of ATP in the degenerate ATP-binding site is crucial to the functional stability of CFTR. Small molecules targeting site 1 may bear therapeutic potential to overcome the membrane instability of F508del-CFTR. KEY POINTS: During evolution, many ATP-binding cassette transporters - including the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel, whose dysfunction causes cystic fibrosis (CF) - lose the ability to hydrolyse ATP in one of the two ATP-binding sites. Here we show that tight ATP binding at this degenerate site in CFTR is central for maintaining the stable, robust function of normal CFTR. We also demonstrate that membrane instability of the most common CF-causing mutant, F508del-CFTR, can be rescued by strengthening ATP binding at CFTR's degenerate site. Our data thus explain an evolutionary puzzle and offer a potential therapeutic strategy for CF.

Genome-wide association studies identify 137 genetic loci for DNA methylation biomarkers of aging

BACKGROUND

Biological aging estimators derived from DNA methylation data are heritable and correlate with morbidity and mortality. Consequently, identification of genetic and environmental contributors to the variation in these measures in populations has become a major goal in the field.

RESULTS

Leveraging DNA methylation and SNP data from more than 40,000 individuals, we identify 137 genome-wide significant loci, of which 113 are novel, from genome-wide association study (GWAS) meta-analyses of four epigenetic clocks and epigenetic surrogate markers for granulocyte proportions and plasminogen activator inhibitor 1 levels, respectively. We find evidence for shared genetic loci associated with the Horvath clock and expression of transcripts encoding genes linked to lipid metabolism and immune function. Notably, these loci are independent of those reported to regulate DNA methylation levels at constituent clock CpGs. A polygenic score for GrimAge acceleration showed strong associations with adiposity-related traits, educational attainment, parental longevity, and C-reactive protein levels.

CONCLUSION

This study illuminates the genetic architecture underlying epigenetic aging and its shared genetic contributions with lifestyle factors and longevity.

Association of Age-Related Hearing Impairment With Physical Functioning Among Community-Dwelling Older Adults in the US

IMPORTANCE

Hearing impairment, a common treatable condition, may contribute to poorer physical function with aging.

OBJECTIVE

To assess whether hearing impairment is associated with poorer physical function, reduced walking endurance, and faster decline in physical function.

DESIGN, SETTING, AND PARTICIPANTS

In this cohort study, cross-sectional and longitudinal analyses were performed using data from the 2011 to 2019 period of the Atherosclerosis Risk in Communities study, a population-based study of community-dwelling adults at 4 sites in the US.

EXPOSURES

Hearing thresholds (per 10 dB) assessed with pure tone audiometry and categorized as normal hearing or mild, moderate, or severe hearing impairment.

MAIN OUTCOMES AND MEASURES

Physical function was assessed using the short physical performance battery (SPPB), with composite scores ranging from 0 to 12. A composite score of 6 or less and a score for each component (balance, gait speed, and chair stands) of 2 or less indicated poor performance. Walking endurance was assessed using a 2-minute fast-paced walk test. Tobit regression models adjusted for sociodemographic factors and medical history were used to calculate the mean differences in SPPB composite scores; logistic regression models, to estimate the odds ratios (ORs) of low SPPB composite and component scores; and linear mixed-effects models, to estimate the mean rate of change in SPPB composite scores over time.

RESULTS

Of the 2956 participants (mean [SD] age, 79 [4.6] years) who attended study visit 6 between 2016 and 2017, 1722 (58.3%) were women, and 2356 (79.7%) were White. As determined by pure tone audiometry, 973 (33%) participants had normal hearing, 1170 (40%) had mild hearing impairment, 692 (23%) had moderate hearing impairment, and 121 (4%) had severe hearing impairment. In the Tobit regression model, severe hearing impairment was associated with a lower mean SPPB score (β, -0.82; 95% CI, -0.34 to -1.30) compared with normal hearing. In fully adjusted logistic regression models, hearing impairment was associated with higher odds of low physical performance scores (severe impairment vs normal hearing: OR for composite physical performance, 2.51 [95% CI, 1.47-4.27]; OR for balance, 2.58 [95% CI, 1.62-4.12]; OR for gait speed, 2.11 [95% CI, 1.03-4.33]). Over time (2 to 3 visits; maximum, 8.9 years), participants with hearing impairment had faster declines in SPPB compared with those with normal hearing (moderate hearing impairment × time interaction, -0.34 [-0.52 to -0.16]). In adjusted models for walking endurance, participants with moderate or severe hearing impairment walked a mean distance of -2.81 m (95% CI, -5.45 to -0.17 m) and -5.31 m (95% CI, -10.20 to -0.36 m) than those with normal hearing, respectively, during the 2-minute walk test.

CONCLUSIONS AND RELEVANCE

In this cohort study, hearing impairment was associated with poorer performance, faster decline in physical function, and reduced walking endurance. The results of the longitudinal analysis suggest that hearing impairment may be associated with poorer physical function with aging. Whether management of hearing impairment could delay decline in physical function requires further investigation.

Proteomics and Epidemiological Models of Human Aging

Human aging is associated with a decline of physical and cognitive function and high susceptibility to chronic diseases, which is influenced by genetics, epigenetics, environmental, and socio-economic status. In order to identify the factors that modulate the aging process, established measures of aging mechanisms are required, that are both robust and feasible in humans. It is also necessary to connect these measures to the phenotypes of aging and their functional consequences. In this review, we focus on how this has been addressed from an epidemiologic perspective using proteomics. The key aspects of epidemiological models of aging can be incorporated into proteomics and other omics which can provide critical detailed information on the molecular and biological processes that change with age, thus unveiling underlying mechanisms that drive multiple chronic conditions and frailty, and ideally facilitating the identification of new effective approaches for prevention and treatment.

Association of hearing impairment with higher level physical functioning and walking endurance: Results from the Baltimore Longitudinal Study of Aging (BLSA)

BACKGROUND

Although hearing impairment (HI) is linked to poorer physical functioning, the longitudinal associations between HI and higher-level functional measures are unclear.

METHODS

Data is from the Baltimore Longitudinal Study of Aging (2012-2019). Using pure-tone audiometry, we categorized hearing into normal, mild, and moderate or greater HI. Physical function was assessed with the expanded Short Physical Performance Battery (eSPPB) and walking endurance with time to walk 400m. Multivariable and mixed-effects linear models tested the hypotheses that participants with HI, at baseline, have poorer physical performance and walking endurance, and faster decline over time (up to six measurements). In a subset (n=526), we further adjusted for vestibular function. Among participants with HI, we evaluated the differences in eSPPB scores and walking endurance between hearing aid users and nonusers.

RESULTS

Of 831 participants 26% had mild, and 17% moderate or greater HI. Adjusting for demographics and medical history, moderate or greater impairment vs. normal hearing, was associated with poorer function (0.17 [95% CI: 0.09, 0.26] lower eSPPB score, and 13.3 [95% CI: 3.31, 23.4] seconds slower 400m time) and faster decline in these parameters over 6 years. Adjustment for vestibular function did not attenuate these associations. Hearing aid users walked 400m 24 seconds faster than nonusers (p=0.001).

CONCLUSION

Moderate or greater HI is associated with poorer initial and greater decline in higher-level physical performance. The observation that hearing aid users had better walking endurance suggests that screening for and treatment of HI may delay or slow progression of hearing-related functional decline.

Association between walking energetics and fragmented physical activity in mid-to-late life

BACKGROUND

Physical activity becomes increasingly fragmented with age, which may be an early marker of functional decline. Energetic cost of walking and energy capacity are also linked with functional decline, but their associations with activity fragmentation, and the potential modifying roles of total daily physical activity and age, remains unclear.

METHODS

493 participants (50-93 years) from the Baltimore Longitudinal Study of Aging underwent measures of: energetic cost of usual-paced overground walking (ml/kg/m), energy demand during slow walking (ml/kg/min) on a treadmill (0.67 m/s, 0% grade),m/s, 0% grade), and average peak walking energy expenditure (ml/kg/min) during a fast-paced 400-m walk. A ratio of slow walking to peak walking energy expenditure ("cost-to-capacity ratio") was calculated. Activity fragmentation was quantified as an active-to-sedentary transition probability (ASTP) using Actiheart accelerometer data. Linear regression models with ASTP as the dependent variable were used to test whether poorer energy cost and capacity were associated with higher ASTP and whether the associations differed by daily physical activity or age.

RESULTS

After adjusting for demographics, body composition, comorbidities and daily physical activity, every 10% higher cost-to-capacity ratio was associated with 0.4% greater ASTP (p=0.005). This association was primarily driven by the least active participants (pinteraction=0.023). Peak walking energy expenditure was only associated with ASTP among participants aged ≥70 years.

CONCLUSIONS

Higher cost-to-capacity ratio and lower energy capacity may manifest as more fragmented physical activity, especially among those less active or aged ≥70 years. Future studies should examine whether an increasing cost-to-capacity ratio or declining energy capacity predicts subsequent activity fragmentation.

Impact of obstructive sleep apnea on assisted ventilation in children with asthma exacerbation

OBJECTIVE

To determine the impact of obstructive sleep apnea (OSA) on asthma exacerbation severity in children hospitalized for asthma exacerbation.

HYPOTHESIS

OSA is associated with greater use of invasive mechanical ventilation (IMV) and noninvasive mechanical ventilation (NIMV) in children hospitalized for asthma exacerbation.

STUDY DESIGN

A retrospective cohort study.

PATIENT-SUBJECT SELECTION

Hospitalization records of children aged 2-18 years admitted for acute asthma exacerbation were obtained for 2000, 2003, 2006, 2009, and 2012 from the Kids' Inpatient Database.

METHODOLOGY

The primary exposure was OSA, the primary outcome was IMV, and secondary outcomes were NIMV, length of hospital stay (LOS), and inflation-adjusted cost of hospitalization. Multivariable logistic regression, negative binomial, and linear regression were conducted to ascertain the impact of OSA on primary and secondary outcomes. Exploratory analyses investigated the impact of obesity on primary and secondary outcomes.

RESULTS

Among 564,467 hospitalizations for acute asthma exacerbation, 4209 (0.75%) had OSA. Multivariable regression indicated that OSA was associated with IMV (adjusted odds ratio [OR], 5.33 [95% confidence interval, CI: 4.35-6.54], p < .0001), NIMV (adjusted OR, 8.30 [95% CI: 6.56-10.51], p < .0001), longer LOS (adjusted incidence rate ratio, 1.34 [95% CI 1.28-1.43], p < .0001), and greater inflation-adjusted cost of hospitalization (adjusted β, 0.38 [95% CI: 0.33-0.43], p < .0001). Obesity was also significantly associated IMV, NIMV, longer LOS, and greater inflation-adjusted cost of hospitalization. There was no interaction between OSA and obesity.

CONCLUSION

OSA is an independent risk factor for IMV, NIMV, longer LOS, and elevated inflation-adjusted costs of hospitalization in children hospitalized for asthma exacerbation.

The burden of obstructive sleep apnea in pediatric sickle cell disease: a Kids' inpatient database study

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is associated with cardiovascular and cerebrovascular morbidity. Patients with sickle cell disease (SCD) are at increased risk for both neurologic complications (NC) and OSA. However, the relationship between OSA and SCD complications is unclear. We hypothesized that there would be an association between OSA diagnosis and SCD complications.

METHODS

Hospital discharge records of patients with SCD aged < 19 years were obtained for the years 1997, 2000, 2003, 2006, 2009, and 2012 from the Kid's Inpatient Database. The primary outcome, NC, a composite of stroke, transient ischemic attack, and seizures. Secondary outcomes included acute chest syndrome (ACS), vaso-occlusive crisis, length of hospital stay, and inflation-adjusted cost of hospitalization. Multivariable regression was conducted to ascertain the association of OSA with primary and secondary outcomes. Analyses were adjusted for the use of noninvasive mechanical ventilation (NIMV) to determine its role as NC risk modifier.

RESULTS

There were 203,705 SCD discharges included in the analysis, of which 2,820 (1.4%) and 4,447 (2.2%) also included OSA and NC diagnoses. Multivariable logistic regression indicated that OSA was associated with NC (adjusted odds ratio [OR], 1.50 [95% CI 1.02-2.21], p = 0.039) and ACS (OR, 1.34 [95% CI 1.08-1.67], p = 0.009) in children with SCD. In the multivariable analysis adjusted for NIMV, the significant association between OSA and NC was no longer observed (OR, 1.39 [95% CI 0.94-2.05], p = 0.100).

CONCLUSIONS

OSA is associated with a 50% increase of odds of NC in children with SCD in this nationwide dataset. The use of NIMV to treat OSA may modify the risk of OSA-associated NC.

Frailty as a predictor of outcomes for patients undergoing carotid artery stenting

OBJECTIVE

The concept of frailty has been proposed to capture the vulnerability resulting from aging and has been implemented for the prediction of perioperative outcomes. Carotid artery stenting (CAS) is considered an appropriate minimally invasive procedure for patients considered to high risk to undergo carotid endarterectomy. Recently, the predictive accuracy for perioperative outcomes using the five-item modified frailty index (5mFI) has been reported to be relatively poor for cardiovascular surgery compared with other surgeries. The effects of functional status and the 5mFI on the outcomes after CAS remain unknown. Thus, in the present study, we investigated the relationship between 5mFI, functional status, and perioperative outcomes.

METHODS

All the patients who had undergone CAS in the Vascular Quality Initiative from November 15, 2016 to December 31, 2018 were included. Good functional status was defined as the ability to perform all predisease activities without restriction using a new variable added to the Vascular Quality Initiative from November 15, 2016 onward. The 5mFI was calculated using functional status and a history of diabetes, chronic obstructive pulmonary disease, congestive heart failure, and hypertension. The perioperative outcomes included in-hospital stroke or death within 30 days after CAS, a prolonged postoperative stay (≥2 days), and non-home discharge. The associations between functional status, 5mFI, and perioperative outcomes were examined using univariate and multivariable logistic regression, adjusting for sex, age, race, degree of stenosis, symptomatic status, and the usage of preoperative medications. An analysis stratified by functional status was also performed.

RESULTS

Of the 7836 patients, 188 (2.4%) had experienced perioperative stroke or death, 765 (9.8%) had required a non-home discharge, and 2584 (33.0%) had required a prolonged postoperative stay. A higher (≥0.6 vs <0.6) 5mFI score was associated with greater odds of perioperative stroke or death (adjusted odds ratio [aOR], 2.75; 95% confidence interval [CI], 1.42-5.28; P = .003), non-home discharge (aOR, 2.70; 95% CI, 1.89-3.85; P < .001), and a prolonged postoperative length of stay (aOR, 1.96; 95% CI, 1.56-2.46; P < .001). For the predictive accuracy of the perioperative outcomes, the 5mFI model had an area under the curve for in-hospital stroke or death, non-home discharge, and prolonged postoperative length of stay of 0.714, 0.767, and 0.668, respectively. The functional status model was not inferior to the 5mFI model for any of these outcomes. In the subgroup analysis, of the asymptomatic patients, a higher 5mFI score was associated with greater odds of perioperative stroke or death (aOR, 7.08; 95% CI, 2.02-24.48; P = .002), non-home discharge (aOR, 5.87; 95% CI, 2.45-13.90; P < .001), and a prolonged postoperative stay (aOR, 2.60; 95% CI, 1.82-3.71; P < .001).

CONCLUSIONS

Frailty, as measured using the 5mFI, and functional status were independent predictors of perioperative stroke or death, non-home discharge, and an increased length of stay for patients undergoing CAS. These results were greatly pronounced in asymptomatic patients. The results from the present study, thus, caution against the use of CAS for asymptomatic frail patients.

The impact of obstructive sleep apnea on bronchiolitis severity in children with Down syndrome

OBJECTIVES

Acute bronchiolitis commonly causes respiratory failure in children ≤2 years, and is particularly severe in those with Down syndrome (DS). Obstructive sleep apnea (OSA), common in DS, is also associated with respiratory complications. However, it is unknown whether OSA is associated with worse outcomes in children with and without DS, hospitalized with bronchiolitis. We hypothesized that in children with bronchiolitis, OSA is associated with worse outcomes in those with DS, independent of DS-related comorbidities.

METHODS

Hospital discharge records of children with bronchiolitis aged ≤2 years were obtained for 1997-2012 from the Kid's Inpatient Database. The primary outcome was invasive mechanical ventilation (IMV), and secondary outcomes were non-invasive mechanical ventilation (NIMV), length of hospital stay, and inflation-adjusted cost of hospitalization (IACH). Multivariable regression was conducted to ascertain the associations between OSA and primary and secondary outcomes accounting for DS-associated comorbidities.

RESULTS

There were 928,961 hospitalizations for bronchiolitis. The DS group with bronchiolitis (n = 8697) was more likely to have OSA [241 (2.77%) vs 1293 (0.14%), p < 0.001] compared to the non-DS group (n = 920,264). Multivariable logistic regression showed that OSA was associated with IMV (adjusted odds ratio [OR], 3.32 [95% CI 2.54-4.35], p < 0.0001) in all children with bronchiolitis; and in those with DS, it was associated with IMV (adjusted OR, 2.34 [95% CI 1.38-3.97], p = 0.002), NIMV (adjusted OR, 8.21 [95% CI 4.48-15.04], p < 0.0001) and IACH (adjusted β, 0.18 [95% CI 0.02-0.34], p = 0.031).

CONCLUSIONS

OSA is independently associated with assisted ventilation in all children hospitalized with bronchiolitis, regardless of DS-associated comorbidities in those with DS. The severity of bronchiolitis in children with DS may be driven by the high prevalence of OSA.

Analysis of Hearing Loss and Physical Activity Among US Adults Aged 60-69 Years

IMPORTANCE

Hearing loss may be a modifiable factor associated with decreased physical activity in older adults.

OBJECTIVE

To examine the association of hearing loss with objectively measured physical activity, including moderate-to-vigorous physical activity, light-intensity physical activity, sedentary behavior, and pattern of physical activity (physical activity fragmentation).

DESIGN, SETTING, AND PARTICIPANTS

This population-based cross-sectional study used National Health and Nutrition Examination Survey (NHANES) data collected in the 2003 to 2004 cycle and analyzed in 2017 to 2020. Participants aged 60 to 69 years with complete audiometry, physical activity, and comorbidity data were included in the analysis. Data analysis was performed from January 2017 to December 2020.

EXPOSURES

Hearing defined by the pure tone average (PTA; range, 0.5-4 kHz) in the better ear, with normal PTA defined as less than 25 dB hearing loss, mild hearing loss defined as PTA 25 to less than 40 dB hearing loss, and moderate or greater hearing loss defined as a PTA greater than or equal to 40 dB hearing loss.

MAIN OUTCOMES AND MEASURES

The primary outcomes were comprehensive metrics of objectively measured physical activity, including time spent in moderate-to-vigorous physical activity, light-intensity physical activity, and sedentary behavior, and physical activity fragmentation. Linear regression was used to model the association between hearing loss and physical activity.

RESULTS

Of the 291 participants (mean [SD] age, 64.53 [2.96] years), 139 (47.8%) were male, 48 (16.5%) had mild hearing loss, and 22 (7.6%) had moderate or greater hearing loss. After adjusting for age, sex, education, race/ethnicity, and comorbidities, hearing loss (vs normal hearing) was significantly associated with less time spent in moderate-to-vigorous physical activity by 5.53 minutes per day (95% CI, -10.15 to -0.90 minutes per day), less time spent in light-intensity physical activity by 28.55 minutes per day (95% CI, -53.07 to -4.02 minutes per day), more time spent in sedentary behaviors by 34.07 minutes per day (95% CI, 8.32 to 59.82 minutes per day), and more fragmented physical activity pattern by 0.38 SD higher in active-to-sedentary transition probability (95% CI, to 0.10 to 0.65). The magnitude of the association of hearing loss (vs normal hearing) with physical activity metrics was equivalent to 7.28 years (95% CI, 3.19 to 11.37 years) of accelerated age for moderate-to-vigorous physical activity, 5.84 years (95% CI, 1.45 to 10.23 years) of accelerated age for light-intensity physical activity, and 10.53 years (95% CI, 2.89 to 18.16 years) of accelerated age for degree of physical activity fragmentation.

CONCLUSIONS AND RELEVANCE

These findings suggest that hearing loss is associated with a worse physical activity profile. Whether interventions to address hearing loss in adults could improve physical activity profiles will require further study.

Prevalence of Concurrent Functional Vision and Hearing Impairment and Association With Dementia in Community-Dwelling Medicare Beneficiaries

IMPORTANCE

Impairments in vision or hearing are common and have been independently linked to higher risk of dementia in older adults. There is a limited understanding of the prevalence of concurrent functional vision and hearing impairment (dual sensory impairment) and its contribution to dementia risk.

OBJECTIVE

To examine the age-specific prevalence of functional dual sensory impairment among older adults, and to investigate the cross-sectional and 7-year longitudinal associations between functional dual sensory impairment and dementia.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study of 7562 older adults used data from the US National Health and Aging Trends Study (NHATS), a nationally representative cohort study of community-dwelling, Medicare beneficiaries aged 65 years and older in the US. Participants in the study with complete data on hearing, vision, and dementia were included in analysis. Data were collected between 2011 and 2018, and between March 2018 and May 2020.

EXPOSURES

Self-reported functional sensory impairments (ie, no sensory impairment, functional vision impairment only, functional hearing impairment only, and functional dual sensory impairment).

MAIN OUTCOMES AND MEASURES

Age-specific prevalence of functional sensory impairments was calculated. Generalized linear regression with a complementary log-log link and a discrete time proportional hazards model with a complementary log-log link were used to assess the cross-sectional and 7-year longitudinal hazard of dementia.

RESULTS

Of 7562 participants, 3073 (40.7%) were ages 80 years or older and 4411 (58.3%) were women. Overall, 5.4% (95% CI, 4.7%-6.1%) of participants reported functional vision impairment only, 18.9% (95% CI, 18.9%-17.8%) reported functional hearing impairment only, and 3.1% (95% CI, 2.7%-3.5%) reported functional dual sensory impairment (prevalence estimates are weighted). Participants reporting sensory impairments were older (no impairment: age ≥90 years, 2.12% [95% CI, 1.79%-2.46%] vs functional dual sensory impairment: age ≥90 years, 20.06% [95% CI, 16.02%-24.10%]), had lower education (no impairment: <high school, 19.05% [95% CI, 17.27%-20.83%] vs functional dual sensory impairment: <high school, 46.15% [95% CI, 38.38%-53.92%]), and greater disease burden (eg, heart disease: no impairment, 15.30% [95% CI, 14.04%-16.55%] vs functional dual sensory impairment, 25.49% [95% CI, 19.96%-31.02%]). Compared with no impairment, functional vision impairment (adjusted hazard ratio [aHR], 1.89; 95% CI, 1.57-2.28), functional hearing impairment (aHR, 1.14; 95% CI, 1.00-1.31), and functional dual sensory impairment (aHR, 2.00; 95% CI, 1.57-2.53) were associated with a higher cross-sectional hazard of dementia. Over 7 years, functional vision impairment (aHR, 1.40; 95% CI, 1.12-1.74), functional hearing impairment (aHR, 1.09; 95% CI, 0.95-1.24), and functional dual sensory impairment (aHR, 1.50; 95% CI, 1.12-2.02) were associated with a higher hazard of incident dementia compared with no impairment.

CONCLUSIONS AND RELEVANCE

In this cohort study of US Medicare beneficiaries, dual sensory impairment was prevalent in older adults and associated with increased risk of dementia. These findings suggest that sensory rehabilitative interventions for multiple impairments may be an additional resource in efforts to reduce dementia risk.

Longitudinal Association Between Energy Regulation and Fatigability in Mid-to-Late Life

BACKGROUND

Deficits in energy production and utilization have been linked to higher fatigue and functional decline with aging. Lesser known is whether individuals with a combination of low peak energy capacity and high energy costs for mobility (eg, impaired energy regulation) are more likely to experience the onset and progression of high fatigability with aging.

METHODS

Participants in the Baltimore Longitudinal Study of Aging (n = 651, 49.0% male, mean age 71.9, range 50-94) with ≥2 visits who completed fatigability (Borg rating of perceived exertion [RPE] after a 5-minute 1.5 mph treadmill walk), slow walking energy expenditure (VO2 mL/kg/min), and peak walking energy expenditure (VO2 mL/kg/min), testing between 2007 and 2018. The longitudinal association between each measure of energy expenditure, a ratio of energy cost-to-capacity, and perceived fatigability was modeled using mixed effects models adjusted for age, body composition, and comorbidities. Time to higher perceived fatigability (RPE ≥ 10) was modeled using Cox proportional hazards models.

RESULTS

In continuous analyses, higher slow walking energy expenditure (p < .05) and a higher cost ratio (p ≤ .001) were associated with greater perceived fatigability over time. Cox proportional hazards models using tertiles of the cost ratio suggest that, compared to those in the lowest tertile, those in the middle and highest tertiles had 1.89 (95% confidence interval [CI]: 1.57-5.16) and 2.85 (95% CI: 1.05-3.40) times greater risk of developing higher fatigability, respectively.

CONCLUSION

Findings suggest that strategies to prevent fatigability should consider methods to improve energy regulation by targeting both the independent and combined effects of declining peak capacity and rising energy costs for mobility with aging.

Poor Mitochondrial Health and Systemic Inflammation? Testing of a Classical Hypothesis

Chronic low-grade inflammation often occurs with aging and has been associated with negative health outcomes. Despite extensive research on the origins of “inflammaging”, the causative mechanisms remain unclear. However, a connection between poor mitochondrial health and chronic inflammation has been hypothesized, with decreasing mitochondrial function occurring with age and precipitating an increase in reactive oxygen species and other pro-inflammatory macromolecules such as mitochondrial DNA. We tested this hypothesis on a population of 619 subjects from the Baltimore Longitudinal Study of Aging, measuring muscle mitochondrial oxidative capacity in vivo by phosphorus magnetic resonance spectroscopy (P-MRS), and plasma interleukin (IL)-6, the most widely used biomarker of inflammaging. The P-MRS-derived post-exercise phosphocreatine recovery time constant tau-PCr, a measure of oxidative capacity, was expressed as a categorical variable through assignment to quintiles. Participants in the first quintile of tau-PCr (best mitochondrial function) were taken as reference and compared to the others using linear regression analysis adjusted for sex, age, lean and fat body mass, and physical activity. Those participants with the lowest oxidative capacity had significantly higher log(IL-6) levels as compared to the reference group. However, data from the other quintiles was not significantly different from the reference values. In conclusion, severe impairment of oxidative capacity is associated with increased inflammation. This study design does not provide conclusive evidence of whether increased inflammation and impaired bioenergetic recovery are both caused by underlying poor health status, or whether mitochondrial deficits lead directly to the observed inflammation; we anticipate addressing this important question with longitudinal studies.

Impact of Fear of Falling on Future Falls and Changes in Physical Activity in Older Adults With Glaucoma

To understand how Fear of falling (FoF) alters mobility, FoF was evaluated annually in 243 older adults (median age=70) with varying degrees of visual field loss from glaucoma, and Rasch-analyzed FoF scores associated with the likelihood of falling in the following year (judged by prospective calendar data) and changes in physical activity (Judged by annual accelerometer trials). At lower FoF levels, each one-unit worsening in FoF was associated with a 2.73-fold higher odds of reporting a fall in the next year (95% CI:1.55,4.81) but not with average daily steps taken (p = 0.44). At higher FoF levels, inter-year changes in FoF were not significantly associated with a fall in the next year (p = 0.78); but were associated with 407 fewer daily steps taken per one-unit change in FoF (95% CI:-743,-71). FoF is an important driver of mobility; the specific aspects of mobility affected varies by the degree of FoF.

The Association Between Hearing and Physical Functioning in the Atherosclerosis Risk in Communities Study

Hearing loss is highly prevalent among older adults and has deleterious effects on health. However, its association with physical functioning is not well defined. We investigated the cross-sectional association between hearing and physical function in 3,339 community-dwelling participants (mean age: 79 years, 59% women) of the Atherosclerosis Risk in Communities Study (ARIC). Hearing was measured by pure-tone average ([dB]) of 4 frequencies [0.5,1,2,4 kHz] and physical function was measured using the short physical performance battery (SPPB), which consisted of 3 performance-based tests (balance, gait speed, and chair stands) each scored ranging from 0-4, resulting in a total possible score of 0-12 (higher scores indicating better physical function). We estimated the association between hearing and physical function using continuous scores for each component of the battery, and the overall SPPB score categorized into high [10-12], intermediate [7-9], and low [≤6]) using ordinal logistic regression models. The SPPB scores were reversed for an easier interpretation of the odds ratios (OR). The category with better physical functions was the reference group for each model. After adjustment for demographics and comorbidities, poorer hearing (+10 dB in PTA) was associated with worse physical functioning: OR for lower balance score=1.17, 95% CI [1.08, 1.26]; OR for lower gait speed score=1.15, 95%CI [1.06, 1.25]; OR for lower chair stand score=1.07, 95% CI [1.04, 1.11]; and OR for lower overall SPPB category=1.15, 95%CI [1.07, 1.24]. Hearing loss is associated with poorer physical functioning, highlighting the potentially negative impact of hearing loss on mobility at older ages.

Changes in the place of death for older adults with cancer: Reason to celebrate or a risk for unintended disparities?

BACKGROUND

Place of death is important to patients and caregivers, and often a surrogate measure of health care disparities. While recent trends in place of death suggest an increased frequency of dying at home, data is largely unknown for older adults with cancer.

METHODS

Deidentified death certificate data were obtained via the National Center for Health Statistics. All lung, colon, prostate, breast, and pancreas cancer deaths for older adults (defined as >65 years of age) from 2003 to 2017 were included. Multinomial logistic regression was used to test for differences in place of death associated with sociodemographic variables.

RESULTS

From 2003 through 2017, a total of 3,182,707 older adults died from lung, colon, breast, prostate and pancreas cancer. During this time, hospital and nursing home deaths decreased, and the rate of home and hospice facility deaths increased (all p < 0.001). In multivariable regression, all assessed variables were found to be associated with place of death. Overall, older age was associated with increased risk of nursing facility death versus home death. Black patients were more likely to experience hospital death (OR 1.7) and Hispanic ethnicity had lower odds of death in a nursing facility (OR 0.55). Since 2003, deaths in hospice facilities rapidly increased by 15%.

CONCLUSION

Hospital and nursing facility cancer deaths among older adults with cancer decreased since 2003, while deaths at home and hospice facilities increased. Differences in place of death were noted for non-white patients and older adults of advanced age.

Longitudinal Changes in Resting Metabolic Rates with Aging Are Accelerated by Diseases

Resting metabolic rate (RMR) declines with aging and is related to changes in health status, but how specific health impairments impact basal metabolism over time has been largely unexplored. We analyzed the association of RMR with 15 common age-related chronic diseases for up to 13 years of follow-up in a population of 997 participants to the Baltimore Longitudinal Study of Aging. At each visit, participants underwent measurements of RMR by indirect calorimetry and body composition by DEXA. Linear regression models and linear mixed effect models were used to test cross-sectional and longitudinal associations of RMR and changes in disease status. Cancer and diabetes were associated with higher RMR at baseline. Independent of covariates, prevalent COPD and cancer, as well as incident diabetes, heart failure, and CKD were associated with a steeper decline in RMR over time. Chronic diseases seem to have a two-phase association with RMR. Initially, RMR may increase because of the high cost of resiliency homeostatic mechanisms. However, as the reserve capacity becomes exhausted, a catabolic cascade becomes unavoidable, resulting in loss of total and metabolically active mass and consequent RMR decline.

Assessment of Racial Differences in Rates of Autopsy in the US, 2008-2017

This cohort study assesses the racial differences in rates of autopsy in groups of decedents older than 18 years from 2008 to 2017 in the US Centers for Disease Control and Prevention Wide-Ranging Online Data for Epidemiologic Research database.

Poor mitochondrial health and systemic inflammation? Test of a classic hypothesis in the Baltimore Longitudinal Study of Aging

Although a persistent inflammatory state has long been associated with aging and negative health outcomes, the underlying mechanisms remain unclear. Mitochondrial dysfunction has been proposed as a cause of inflammaging, but evidence of an association in humans is lacking. In this study, we analyzed the cross-sectional association between inflammatory biomarkers and mitochondrial oxidative capacity in skeletal muscle, assessed as post-exercise phosphocreatine recovery time constant by phosphorus magnetic resonance spectroscopy, in a population of 669 adults (mean age 67 years) from the Baltimore Longitudinal Study of Aging. We observed that participants with lower mitochondrial oxidative capacity exhibited hallmarks of inflammation, specifically markedly higher levels of interleukin-6 and C-reactive protein, as well as increased erythrocyte sedimentation rate when compared with participants with better oxidative capacity, independent of age and sex. We speculate that this association reflects the observation that products of damaged mitochondria, such as mitochondrial DNA, activate multiple pathways that lead to inflammation. Furthermore, excess production of oxidative species (ROS) by dysfunctional mitochondria could trigger inflammation either directly via NF-κB or through oxidative damage to proteins, lipids, and nucleic acids. Longitudinal studies are necessary to ascertain whether and through which mechanisms mitochondrial dysfunction activate inflammation or whether both these phenomena derive from a common root.

Characterizing the Impact of Fear of Falling on Activity and Falls in Older Adults with Glaucoma

OBJECTIVE

Fear of falling (FoF) may alter mobility in older adults, especially among those with visual impairment. Using a longitudinal prospective cohort of older glaucoma patients, we investigated whether and how FoF is associated with future falls and physical activity.

DESIGN

Prospective observational cohort study.

SETTING

Hospital-based single-center recruitment.

PARTICIPANTS

Individuals with glaucoma or suspected glaucoma.

MEASUREMENTS

FoF was measured annually over a 3-year period using the University of Illinois at Chicago FoF Questionnaire, with lower Rasch-analyzed FoF scores (in logit units) indicating less fear. Participants recorded falls prospectively over the 3-year period using monthly mail-in calendars. Daily steps were collected annually over 7 days using an accelerometer. Visual field (VF) sensitivity was derived by combining sensitivities from monocular VF results. Participants completed questionnaires to determine other demographic/health characteristics. Multivariate random effects models evaluated within-participant changes in fall rates and physical activity across study years.

RESULTS

At lower FoF levels (FoF≤0), each one-unit worsening in FoF score across study years was associated with 2.73 times higher odds of reporting at least one fall in the next year (95% confidence interval [CI] = 1.55-4.81) but was not associated with average daily steps (P = .44). Similar results were seen when fall rates were normalized by number of steps taken (P = .97). At higher FoF levels (FoF > 0), inter-year changes in FoF scores were not significantly associated with reporting a fall in the following year (P = .78) but were associated with 407 fewer average daily steps per one-unit change in FoF (95% CI = -743 to -71).

CONCLUSION

FoF is an important psychological factor associated with mobility in glaucoma patients, although specific aspects of mobility (fall rates vs activity levels) affected vary by the degree of FoF. Our findings suggest that customizing behavioral interventions for older adults based on their levels of FoF may be an important strategy for fall prevention and activity promotion. J Am Geriatr Soc 68:1847-1851, 2020.

Active-to-Sedentary Behavior Transitions, Fatigability, and Physical Functioning in Older Adults

BACKGROUND

With aging, daily physical activity (PA) becomes less frequent and more fragmented. Accumulation patterns of daily PA-including transitions from active-to-sedentary behaviors-may provide important insights into functional status in older, less active populations.

METHODS

Participants of the Baltimore Longitudinal Study of Aging (n = 680, 50% male, aged 27-94 years) completed a clinical assessment and wore an Actiheart accelerometer. Transitions between active and sedentary states were modeled as a probability (Active-to-Sedentary Transition Probability [ASTP]) defined as the reciprocal of the average PA bout duration. Cross-sectional associations between ASTP and gait speed (m/s), fatigability (rating-of-perceived-exertion [RPE]), 400 m time (seconds), and expanded short physical performance battery score were modeled using linear and logistic regression, adjusted for chronic conditions. Further analyses explored the utility of ASTP over-and-above total daily PA.

RESULTS

In continuous models, each 0.10-unit higher ASTP was associated slower gait (β = -0.06 m/s, SE = 0.01), higher fatigability (β = 0.60 RPE, SE = 0.12), slower 400 m time (β = 16.31 s, SE = 2.70), and lower functioning (β = -0.13 expanded short physical performance battery score, SE = 0.03; p < .001). In categorical analyses, those in the highest tertile of ASTP were >2 times more likely to have high fatigability (rating of perceived exertion ≥10), slow 400 m time (>300 seconds) and reduced functional performance (expanded short physical performance battery score < 3.07) than those in the lowest tertile (p < .01). Further analyses demonstrated ASTP provided additional insight into functional outcomes beyond total daily PA.

CONCLUSION

Fragmented daily PA-as measured by ASTP-is strongly linked with measures of health and functional status and may identify those at risk of high fatigability and reduced functional performance over and above traditional PA metrics.

LONGITUDINAL RELATIONSHIP BETWEEN ENERGY UTILIZATION AND PHYSICAL AND COGNITIVE PERFORMANCE AS A FUNCTION OF AGE

Energy utilization, which becomes more inefficient with age and is measured by a ratio of energy-cost-to-energy-capacity (“cost-ratio”), has been associated with functional decline. However, the interplay between longitudinal changes in energy efficiency and physical/cognitive functioning remains unclear. We investigated this relationship in 1020 participants of the Baltimore Longitudinal Study of Aging (baseline age: 68.9 (IQR: 59.8, 80.5), male: 44.7%). In linear mixed effects models adjusted for baseline age, sex, and height, an increasing cost-ratio was associated with faster decline in usual gait speed among those aged 50-64 years (beta = -0.20 m/s, p = 0.003), and >=65 years (beta = -0.16 m/s, p less than 0.001), but not those less than 50 years (beta = -0.22 m/s, p = 0.178). In models adjusted for baseline age, sex, race, and years of education, higher cost-ratio was associated with faster declines in executive function, as measured by time to finish Trail B, among those aged >=65 years (beta = 22.96 seconds, p = 0.020), but not <50 years (beta = -13.65 seconds, p = 0.557) or 50-64 years (beta = -15.61 seconds, p = 0.353). Together, these results suggest that energy utilization becomes more inefficient in the two to three decades prior to change in physical and cognitive functioning, implying it may act as an early marker of physiological aging. Further research is needed to understand the drivers of energy inefficiency, which may shed light on the biological mechanisms contributing to these declines.

THE RELATIONSHIP OF APOE ε4 TO THE RELATIVE TIMES AND HAZARDS OF DEMENTIA

Although APOE ε4 is an established risk factor for dementia, it is unclear whether it is associated with elevated risk or earlier symptom onset. Longitudinal study of 10,400 white-race individuals in the ARIC cohort followed from age 60 to incident dementia diagnosis, death, or censoring. All-cause dementia was defined using standardized algorithms incorporating longitudinal cognitive change, proxy report, and hospital or death certificate dementia codes. Death was ascertained via the National Death Index and death certificates. We used a parametric mixture of generalized gamma distributions to simultaneously estimate the distribution of event times and the proportion of individuals who experience each outcome (i.e., dementia and its competing risk, dementia-free death) by APOE ε4 status (≥ 1 allele vs. no alleles). Age-adjustment was through use of age as the time scale. APOE ε4 carrier status was associated with a doubling of the overall frequency of dementia incidence to 25% compared to 13% (p < 0.001) in non- ε4 carriers. The distributions of time to dementia was modified by APOE ε4 status (p=0.007): median time to dementia onset among APOE ε4 carriers was 81.9 years compared to 83.3 years in non-APOE ε4 carriers (p = 0.005). No differences in results were found by sex. APOE ε4 carrier status is associated with both elevated risk and earlier time to dementia onset. These findings clarify the causal role of APOE in dementia etiology, could help better identify at-risk subgroups, and may help facilitate better research recruitment.

ASSOCIATION BETWEEN WALKING ENERGETICS AND FRAGMENTED PHYSICAL ACTIVITY IN MID-TO-LATE LIFE

Physical activity becomes increasingly fragmented with age, and may be an early marker of functional decline. Energy regulation has been linked with functional decline, yet whether the energy needed for walking, a common type of physical activity, is related to fragmentation of physical activity remains unknown. The study population included 493 participants aged 50-93 years from the Baltimore Longitudinal Study of Aging. Energetic measures included the energetic cost of usual-paced overground walking (ml/kg/m), the average energy expended (ml/kg/min) during a rapid-paced 400-m walk, and a cost-to-capacity ratio between the energy expended during 5-min treadmill walk (0.67 m/s, 0% grade) and the energy expended during the 400-m walk. Activity fragmentation was extracted from accelerometer data collected over ≥3 valid days and quantified via an active-to-sedentary transition probability (ASTP). Associations between the energetic measures and ASTP were assessed using multivariate linear regression models. Interactions between energetics and total daily physical activity, quantified as total log-transformed activity counts (TLAC), were also assessed. After adjusting for TLAC, demographics, body composition and comorbidity, higher cost-to-capacity ratio was associated with 3.51% greater fragmented physical activity (p=0.005). Energetics by TLAC interactions revealed that lower rapid-paced walking energy expenditure and higher cost-to-capacity ratio were only significantly associated with greater fragmentation in the most sedentary participants (p<0.01 for both). Our results suggest that deterioration of walking efficiency may manifest as a more fragmented physical activity profile, especially among sedentary adults. Future longitudinal studies to understand whether declining walking efficiency predicts the onset and progression of activity fragmentation are warranted.

TRAJECTORIES OF PHENOTYPIC MARKERS OF AGING AS PRECURSORS TO FUNCTIONAL CHANGE

Delineating trajectories of aging phenotypes is essential to understanding mechanisms of clinical disease and disability. We investigated longitudinal changes in measures of body composition, energy expenditure, and brain volumes in >900 participants (age 67.0 (IQR: 57-77) years, 48.1% male) of the Baltimore Longitudinal Study of Aging using mixed effects regression models. Computed tomography-derived thigh muscle cross-sectional area declined 754.2 cm2 per decade at age 60 years (p<0.001) and 1294.3 cm2 at 75 years (p<0.001). Energy reserves, defined as a ratio of energy-cost-to-energy-capacity measured using indirect calorimetry, decreased 11.2% per decade at 60 years (p<0.001), and 16.8% at 75 years (p<0.001). MRI-derived measures of total brain volumes declined 41.6 cm3 per decade at 60 years (p<0.001) and 44.9 cm3 at 75 years (p<0.001). Linking these findings to biological and clinical measures of aging may contribute to more accurate assessment of phenotypic age.

ANALYTICAL CONSIDERATIONS OF DEVELOPING A PHENOTYPIC AGING MEASURE: THE CONCEPTUAL FRAMEWORK MUST COME FIRST!

We propose a latent structural model framework where phenotypic aging is a latent variable influenced by chronological age, genes and environment. Within this framework, phenotypic age influences aging-related outcomes and is reflected by latent domains of aging (body composition, energetics, homeostasis, and neural functioning) reflected by biomarkers. First, we validate the framework by selecting age-associated domain-specific biomarkers and assessing internal consistency and convergent construct validity (Cronbach’s alpha). Using data from the Baltimore Longitudinal Study of Aging, within-domain Cronbach’s alphas ranged from 0.80 to 0.92, supporting convergent construct validity. Second, we evaluate two broad methods for combining biomarkers into one phenotypic age measure customized to different objectives: 1) confirmatory factor analysis of chronological age-adjusted biomarkers to create a measure to identify pleiotropic genetic and environmental mechanisms, and 2) machine-learning methods to create a measure optimizing predictive and concurrent criterion validity. This framework will enable evaluation of candidate biological mechanisms of aging.

Association of Total Daily Physical Activity and Fragmented Physical Activity With Mortality in Older Adults

Importance

Fragmented daily physical activity may be a sign of physiological decline that provides more powerful insight into impending mortality than total daily activity.

Objective

To compare and contrast the association between total daily activity and activity fragmentation, which encompasses activity bouts and duration, and mortality risk.

Design, Setting, and Participants

In this cohort study, accelerometer data from 2007 through 2015 and mortality data from 2007 through 2017 were collected from 548 adults aged 65 years and older participating in the Baltimore Longitudinal Study of Aging. The dates of analysis were November 2016 to June 2019, with data collected through December 31, 2017. Using Cox proportional hazards regression, the association between accelerometer-derived patterns of physical activity and mortality was estimated after adjusting for demographic characteristics, lifestyle factors, and comorbidities.

Exposures

Minute-by-minute physical activity data were collected over a 24-hour, 7-day period (excluding times between 11:00 pm and 4:59 am) using an accelerometer. Each minute was labeled either active or sedentary, and 5 features of accelerometer data were extracted: total daily activity (defined as any activity performed throughout the day), activity fragmentation (defined as an active-to-sedentary transition probability), and 3 measures of activity bouts (<5, 5-10, and ≥10 active minutes).

Main Outcomes and Measures

All-cause mortality.

Results

Among 548 well-functioning older adults (mean [SD] age, 75.8 [7.2] years; 262 [47.8%] women), 61 participants (11.1%) died. Total daily physical activity was not associated with mortality risk (hazard ratio [HR], 0.90 [95% CI, 0.75-1.08]; P = .28). However, more fragmented physical activity patterns were associated with greater mortality risk (HR, 1.49 [95% CI, 1.02-2.19]; P = .04) after adjusting for age, sex, race/ethnicity, body mass index, smoking history, employment, self-reported health, grip strength, usual gait speed, comorbidities, and device wear time. In addition, more frequently engaging in activity bouts lasting less than 5 minutes was associated with greater mortality risk (HR, 1.28 [95% CI, 1.01-1.61]; P = .04), whereas activity bouts of 5 to 10 minutes (HR, 0.99 [95% CI, 0.58-1.69]; P = .97) and 10 minutes or longer (HR, 0.81 [95% CI, 0.65-1.01]; P = .06) were not associated with mortality risk.

Conclusions and Relevance

In this cohort study of well-functioning adults aged 65 years and older, fragmented daily physical activity, particularly activity bouts lasting less than 5 minutes, was associated with greater mortality risk. These findings suggest that activity fragmentation in older adults may precede declines in functional capability and overall physical activity that typically indicate impending mortality.