The Journals of Gerontology: Series A

Background: Mitochondrial dysfunction is a hallmark of ageing and is implicated in the pathogenesis of sarcopenia. Genetically confirmed mitochondrial disease provides a biologically definitive model of impaired oxidative phosphorylation against which novel functional assessments can be validated. We investigated whether a brief, submaximal, non-ischaemic intermittent isometric handgrip exercise protocol combined with Near Infra-Red Spectroscopy (NIRS) could detect distinct muscle oxygenation signatures in mitochondrial disease and sarcopenia. Methods: Adults with genetically confirmed mitochondrial disease (n=10, 7 female) and group-matched controls (n=19, 11 female), underwent assessment of maximal grip force, handgrip relaxation kinetics and a 3-minute intermittent submaximal isometric handgrip test (40% maximal voluntary contraction, 1Hz contraction/relaxation) with continuous force recording at 2000Hz and simultaneous NIRS. Findings were compared with 23 community-dwelling older adults from the Muscle Ageing and Sarcopenia Study (MASS) Lifecourse cohort (n=23, 13 female) including seven with probable or confirmed sarcopenia according to European Working Group on Sarcopenia in Older People (EWGSOP2) criteria. Results: Participants with mitochondrial disease demonstrated an attenuated reduction in tissue saturation index (TSI) during exercise compared with controls (TSI % {middle dot} s150-180s: -59.9 {+/-} 94.5 vs -175.1 {+/-} 128.4; p=0.02). Total haemoglobin (THb) responses did not differ between groups (p=0.10). In contrast, participants with probable or confirmed sarcopenia showed exaggerated reduction in TSI compared with non-sarcopenic participants (TSI % {middle dot} s150-180s: -256.5 {+/-} 146.0 vs -121.2 {+/-} 95.2; p=0.05), while THb responses remained similar. The association between sarcopenia and TSI differed by sex (interaction coefficient -240, p=0.016), with greater TSI reductions observed in males with sarcopenia. Differences in TSI between mitochondrial disease and control groups were independent of age and sex. No statistically significant associations were observed between THb responses and age, sex or force production. Conclusions: A brief, non-ischaemic handgrip exercise protocol combined with NIRS identified divergent muscle oxygenation responses in mitochondrial disease and sarcopenia. The attenuated TSI response observed in genetically confirmed mitochondrial disease is consistent with impaired oxygen utilisation secondary to defective oxidative phosphorylation, whereas the exaggerated TSI reduction observed in sarcopenia suggests a distinct physiological mechanism, potentially involving impaired oxygen delivery, reduced muscle efficiency, or both. This portable and non-invasive approach has significant potential as a physiological biomarker for mechanistic studies and clinical trials in ageing and neuromuscular disease. More broadly, our findings demonstrate how biologically defined rare diseases can provide a powerful framework for interpreting mechanisms in common heterogeneous age-related conditions.

Biological aging, the decline in physiological resilience that increases our vulnerability to disease and death as we grow older, can be measured from standard clinical-laboratory panels. Measurement of biological aging from laboratory data embedded in electronic health records (EHRs) could enhance precision healthcare. However, suitability of EHR-embedded laboratory records for this purpose is uncertain. We evaluated feasibility of EHR biological age measurement in a cohort of n=4,313 cardiothoracic-surgery patients at a large US Hospital and tested whether measured biological aging was associated with patient outcomes. Patients who were biologically older prior to surgery more often died or experienced adverse outcomes as compared to those measured to be biologically younger. Postoperative biological-aging trajectories were associated with length of intensive-care-unit (ICU) stays and in-hospital death. EHR laboratory data provide an opportunity for scalable implementation of biological aging measurement within healthcare systems, with potential to enhance patient monitoring and risk stratification.

Despite recent evidence of the ability of systemic and organ-specific proteomic aging clocks to predict a large range of age-related diseases, their utility in cancer research remains largely underexplored. In this study, we evaluated the predictive ability of systemic and organ-specific proteomic aging clocks for (i) all-cause mortality, (ii) cancer-related mortality, and (iii) cancer incidence in a sample of Finnish twins (N = 401, mean age at baseline 62.3 years) with Olink proteomic data. Participants were followed for a mean of 10.6 years (SD +- 1.6), with estimates from four systemic and 18 organ-specific proteomic aging clocks calculated at baseline. Cox proportional hazards regression models adjusted for sex and age at baseline identified 15 proteomic aging clocks as significant predictors of all-cause mortality (Ncases = 28) after multiple testing correction (FDR < 0.05), with 11 remaining significant after lifestyle adjustment (Ncases = 27). For several clocks, effect sizes were large, with hazard ratios (HR) approximately doubling per one standard deviation (SD) increase in clock estimates. In predicting cancer-related deaths among participants without a prior cancer diagnosis at baseline (Ncases = 9), only the Immune clock showed a significant positive association after multiple testing correction in basic (HR = 2.94, 95% CI: 1.88-4.59) and lifestyle-adjusted models (HR = 3.31, 95% CI: 1.78-6.17). No associations with cancer incidence (Ncases = 34 basic, Ncases = 31 adjusted) survived multiple testing correction, although several nominal associations were observed. In conclusion, our findings suggest that proteomic aging clocks are strong predictors of all-cause and cancer-specific mortality, independent of lifestyle factors. Proteomic aging clocks may further serve as valuable tools for stratifying cancers by mortality risk.

Background: Frailty is a prominent risk factor for dementia. Early detection of at-risk individuals may enable intervention to prevent or slow dementia pathology. Blood-based biomarker discovery could offer a path for early detection of frailty and cognitive decline. Methods: Older adults at risk of dementia underwent comprehensive multi-disciplinary assessment at the Healthy Brain Ageing (HBA) clinic, including geriatric, neurophysiological and mood evaluations, in addition to providing a fasted blood sample. Clinical data were used to calculate a deficit accumulation frailty index (FI) score. Additional cohorts attended either one (n=118) or two (n=73) subsequent visits over an average period of 4 years. Untargeted metabolomics was performed on plasma samples, and metabolites were clustered by similarity. Linear regression was used to assess association of clusters with FI. Finally, change in plasma abundance over time was assessed. Results: At assessment, participants had a mean (SD) age of 68.10 (8.07) years; 72.2% were female. Hierarchical clustering identified 10 clusters of metabolites, of which 6 were significantly associated with FI (p<0.05) at baseline and contained similar classes of metabolite. Differential abundance analysis found unique temporal regulation of metabolite abundance in each cluster, but across clusters severity of frailty impacted direction of change in plasma abundance over time. Conclusions: Frailty index was associated with carboxylic acids and derivatives, fatty acyls and organooxygen compounds across multiple clusters, and a large number of lipids were linked to frailty score, potentially implicating dysregulation of energy metabolism in the pathophysiology of frailty and forming a panel of predictive biomarkers of at risk patients.

Frailty reflects declining physiological reserve across multiple organ systems with aging, yet the underlying biological mechanisms contributing to frailty remain poorly understood. We tested whether somatic mutations in the blood were associated with incident frailty and faster progression in 730,088 participants from UK Biobank, All of Us, BioVU and the Womens Health Initiative. We found that clonal hematopoiesis of indeterminate potential (CHIP) and autosomal mosaic chromosomal alterations showed strong associations with frailty, whereas mosaic loss of chromosome X or Y did not. Findings were consistent across survey-based, directly measured and clinically assessed frailty, as well as healthspan phenotypes. A Tet2 mouse model demonstrated multisystem frailty-like functional decline and T-cell remodeling. In humans, T-cell activation-related proteins directly mediated the association between clonal hematopoiesis and frailty. Collectively, these findings support a model in which clonal hematopoiesis accelerates biological aging through immunosenescence.

Background Attentional control declines with normal aging, yet the role of modifiable lifestyle factors in accelerating this decline remains incompletely characterised in large, diverse populations. We examined associations between four modifiable risk factors (smoking intensity, alcohol binge drinking, social satisfaction and blood pressure) and sustained attention performance in 13,866 adults drawn from the All of Us Research Program. Methods Cognitive performance was assessed using the Gradual-Onset Continuous Performance Task (GradCPT). A composite cognitive efficiency score was derived via principal component analysis of four GradCPT metrics: d' (perceptual sensitivity), response criterion, median reaction time and reaction time variability. Associations between cognitive efficiency and each risk factor were examined using multiple linear regression adjusted for age, sex and race/ethnicity. Effect sizes were expressed as age-equivalent years of cognitive aging (age-equivalent years = regression coefficient for the risk factor divided by the regression coefficient for age) to aid clinical interpretation. Results GradCPT performance declined progressively with age (p < 0.001). Social satisfaction emerged as the strongest lifestyle predictor: low social satisfaction was associated with approximately 5.8 additional age-equivalent years of cognitive aging relative to high social satisfaction. Smoking showed a dose-response pattern, with heavy smokers (> 20 cigarettes/day) exhibiting an approximately 5-year age-equivalent deficit versus never-smokers. Stage 2 hypertension showed a modest, non-significant negative association. Binge drinking showed limited significant associations, likely complicated by survivor and abstainer biases. Bootstrapped analyses of combined exposures showed that combinations of risk factors, particularly those involving low social satisfaction, produced larger cognitive deficits than expected under an additive model. Conclusions These findings support an interactive rather than a purely additive model of lifestyle-related cognitive vulnerability and highlight the GradCPT as a subclinical measure of attention-based cognitive risk in non-clinical populations. Keywords Cognitive aging, Sustained attention, GradCPT, Modifiable risk factors, Social isolation, Smoking, Hypertension, All of Us Research Program

Recent lifespan frameworks of aging theorize that pubertal development and cellular aging are governed by overlapping pathways, but the time lag between adolescence and older adulthood complicates the study of shared molecular mechanisms. Here we compare a DNA-methylation-based epigenetic index of pubertal development to epigenetic clocks, which were designed to measure biological aging, as a putative biomarker of adult aging and health in two adult cohorts: 3,642 older Americans in the Health and Retirement Study (HRS; age range, 56 to 100 years; 2,106 females) and 18,676 adults from Generation Scotland (GS; age range, 18 to 98 years; 10,974 females). Epigenetic puberty was correlated with chronological age in both cohorts, moderately in the older HRS sample (r = 0.51 in females, r = 0.51 in males) and strongly across the wider adult age range of GS (r = 0.82 in females, r = 0.86 in males). In both cohorts, age-residualized epigenetic puberty was associated with accelerated biological aging as measured by epigenetic clocks and other aging biomarkers (standardized coefficients: HRS, 0.13 to 0.47, all P < 0.005; GS, 0.05 to 0.40, all P < 0.001). Epigenetic puberty was linked with multiple health outcomes: mortality in HRS in both sexes (ORs, 1.39 and 1.46, both P [&le;] 0.001) and in GS among females (HR, 1.12, P = 0.003); 10-year onset of diabetes, any cancer and lung disease in GS (HRs, 1.12 to 1.19, all P < 0.005); and with multimorbidity, functional limitations and BMI in females in HRS (standardized coefficients, 0.10 to 0.16, all P < 0.001). It also accounted for a unique, albeit smaller, proportion of variance in aging-related outcomes beyond that explained by epigenetic clocks. These findings indicate that the epigenetic puberty index reflects pro-aging underlying biology, showing overlapping molecular pathways between pubertal development and cellular aging, and support a lifespan-based approach to studying biological aging.

INTRODUCTION: Dementia research in sub-Saharan Africa remains limited despite rapid population aging and substantial ancestral, environmental, and vascular diversity. The Study of Ancestry, Health, Environment, and Late-Life Neurodegeneration (SAHEL) characterizes late-life cognitive decline and neurodegeneration in north-eastern Nigeria. METHODS: SAHEL comprises community and hospital cohorts of adults aged 55 years or older in Yobe and Borno States. Participants undergo cognitive, functional, environmental, cardiovascular, metabolic, neuropsychiatric, and neurological assessments. Blood is collected for clinical profiling and biobanking, and consenting hospital participants provide skin biopsies for induced pluripotent stem cell generation. Planned analyses will integrate gut microbiota profiling, retinal imaging, and brain magnetic resonance imaging to investigate biological pathways and markers associated with healthy aging and cognitive outcomes. RESULTS: From August 2025 through February 2026, 1,044 community participants were screened (mean age, 69.4 years; 56.4% female); 379 (36.3%) screened positive for cognitive concern and entered longitudinal follow-up. The hospital cohort enrolled 102 participants (mean age, 73.5 years; 57.8% male), including participants with Alzheimers disease, vascular dementia, mixed dementia, and mild cognitive impairment. Blood was collected from 809 community participants and all hospital participants. The cohort includes Kanuri, Fulani, Hausa, Babur/Bura, and Shuwa Arab participants. DISCUSSION: SAHEL has established a large, deeply characterized aging and dementia research platform in north-eastern Nigeria. Its linked clinical, environmental, biomarker, genomic, imaging, microbiome, and cellular resources will enable investigation of population-specific risk and resilience mechanisms and strengthen dementia research and precision medicine in African populations.

BackgroundClonal hematopoiesis of indeterminate potential (CHIP) is associated with ageing and atherosclerotic coronary artery disease (CAD), but evidence has largely come from peripheral blood. Whether somatic mutational profiles differ between arterial tissue and blood, and whether hematopoietic clones are represented in arterial tissue, remain poorly understood. MethodsWe performed deep whole-exome sequencing on 302 blood granulocytes and 263 arterial tissues from patients undergoing coronary artery bypass graft surgery, including 221 matched blood-tissue pairs, with mean sequencing depths of 130.5X and 120.8X, respectively. Somatic variants were identified using Mutect2. Associations with age and CAD complexity, assessed using SYNTAX score, were evaluated using multivariable regression. Primary analyses focused on variants with variant allele fractions of 10-25%. ResultsCHIP was detected in 24/302 (7.9%) blood granulocytes, predominantly involving DNMT3A, TET2, and ASXL1. In contrast, somatic mutations in CHIP-associated genes in arterial tissues showed a distinct profile dominated by CALR, SETDB1, and PDSS2. Somatic mutation carrier status increased with age in blood ({beta} = 0.07, p = 0.02) and arterial tissues ({beta} = 0.06, p = 0.04). Blood CHIP was associated with lower SYNTAX score ({beta} = -1.05, p = 2.66 x 10-3), partly driven by DNMT3A carriers ({beta} = -1.06, p = 0.04), whereas arterial CALR mutations were associated with higher SYNTAX score ({beta} = 1.14, p = 0.03). Among 221 matched pairs, only four identical variants, involving CHEK2, DNMT3A, GNB1, and SRSF1, were detected in both compartments. Genome-wide analyses showed compartment specificity, with bile acid metabolism enriched among arterial tissue-specific mutations (PAdj = 0.038). ConclusionBlood and arterial tissues in CAD harbour distinct somatic mutational landscapes with limited cross-compartment sharing. These findings suggest that cardiovascular somatic mutations may reflect both hematopoietic and arterial tissue-associated processes and motivate cell-resolved and spatial studies to define their origins and roles in cardiovascular ageing.

Hallmarks of biological ageing are closely interconnected with neurodegenerative diseases. Deoxyribonucleic acid methylation (DNAm) clocks quantify biological age and may serve as peripheral biomarkers of neurodegenerative diseases. This systematic review and meta-analysis aim to examine associations between DNAm-based biological age metrics and neurodegenerative diseases. Six databases were systematically searched from 1st January 2011 to 15th April 2026 for studies reporting associations between DNAm-based ages and neurodegenerative diseases including all-cause dementia, Parkinson's Disease, Multiple Sclerosis, and Amyotrophic Lateral Sclerosis. Correlated-and-hierarchical-effects meta-analyses were fitted using restricted maximum likelihood with Knapp-Hartung adjustment. Of 42,023 records screened, 37 observational studies (n=46365; 60.5% female; median of mean age 69.4 years [IQR 62.5-73.3)) and seven Mendelian randomization studies met inclusion criteria. In longitudinal meta-analyses, higher GrimAge epigenetic age acceleration (EAA) was significantly associated with higher dementia risk (HR per SD 1.11 [95% CI 1.02-1.20]; I^2 = 0.0%; p = 0.018), whereas Horvath1 EAA, Hannum EAA, PhenoAge EAA, and DunedinPACE were not significantly associated with dementia risk. Evidence for other neurodegenerative diseases were heterogeneous across clock generations and study designs. Mendelian randomization provided limited evidence for causality. Higher GrimAge EAA was the only DNAm age measure consistently predictive of higher all-cause dementia risk. Overall, however, DNAm age clocks show limited and inconsistent associations with neurodegenerative diseases, providing insufficient support for their use as disease biomarkers. These findings highlight the need to develop and independently validate disease-specific DNAm clocks and undertake pathway analyses to identify methylation changes associated with neurodegeneration and the biological processes they reflect.

Individuals with Down syndrome (DS) exhibit accelerated biological aging and unique patterns in disease prevalence. However, empirical characterizations of relative risk and age at onset of disease in this population are not common. Here we aimed to quantify the difference in risk and timing of age-related conditions between individuals with DS when compared to typically developing (TD) matched controls. We used semiparametric Cox proportional hazards models and Restricted Mean Event-Free Age (RMEA) to estimate differences in risk and approximate average age at onset of cataracts, cognitive decline, death, menopause, and osteoporosis. Individuals with DS were at higher risk of all age-related conditions or events and experienced these events at younger ages, excluding menopause. We observed a 24.5-fold higher risk of cognitive decline in individuals with DS (p<0.001), and between a 2- and 4-fold higher risk of the other age-related events or conditions (p<0.01). Cognitive decline and death occurred more than 14 years earlier in individuals with DS and were more likely to co-occur (p<0.001) compared to in TD individuals. These findings have important implications for tailored screening and prevention efforts in aging individuals with DS, as this population experiences a distinct cadence of age-related events.

Background: Blood-based biomarkers (BBMs) may facilitate early detection of Alzheimers disease (AD), yet data in Latino populations remain limited. We examined associations of plasma biomarkers with cognition and depressive symptoms in Spanish-speaking Latino older adults enrolled in the Boston Latino Aging Study (BLAST). Methods: Baseline data from 122 older adults without dementia were analyzed. Plasma AB42/40, brain-derived phosphorylated tau (p-tau) 217, neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) were measured using NULISA. Cognition was assessed with the Latin American Spanish version of the Preclinical Alzheimers Cognitive Composite (LAS-PACC5) and depressive symptoms with the Geriatric Depression Scale (GDS). Regression models were adjusted for age, sex, and education. Results: Cognitively impaired participants had higher p-tau217 and GFAP than cognitively normal participants. Higher p-tau217 and GFAP were associated with poorer LAS-PACC5 performance, while higher NfL was associated with greater depressive symptoms. AB42/40 showed no significant associations. Conclusions: Distinct biomarker associations with cognitive and emotional functioning support further longitudinal evaluation of BBMs for risk characterization in Latino older adults and potential disease monitoring applications.

Apolipoprotein E (APOE) genotype is theorised to influence dementia risk partly through effects on blood-brain barrier (BBB) function, but clinical studies examining APOE effects on BBB biomarkers report inconsistent results. Therefore, this systematic review and meta-analysis quantified associations between APOE genotype and two commonly used fluid biomarkers of CNS barrier function: cerebrospinal fluid (CSF)/serum albumin quotient (Q-Alb), and soluble platelet-derived growth factor receptor beta (sPDGFRB). Ovid MEDLINE, Embase, and Web of Science were searched on 30th June, 2026. Eligible peer-reviewed human studies reported Q-Alb or blood or CSF sPDGFRB; by APOE genotype. Risk of bias was assessed using the Joanna Briggs Institute checklist. Twenty-eight studies involving 5,375 participants were included: 17 assessed Q-Alb and 11 assessed sPDGFRB. Random-effects meta-analyses determined that APOE e2 carriage was associated with higher Q-Alb (g = 0.29, 95% CI 0.11 to 0.46). APOE e4 carriage was not associated with Q-Alb overall (g = .13, 95% CI -.17 to .43) or sPDGFRB overall (g = .10, 95% CI -.21 to .40). Genotype-specific Q-Alb analyses suggested medium positive but non-significant effects among e4/e4 and e2/e4 carrier subgroups. For sPDGFRB, exploratory subgroup analysis revealed effect estimates near zero in cognitively unimpaired participants, and a small positive non-significant effect in cognitively impaired participants. Larger effects were also observed in samples with an older mean age, although this was not statistically significant. Overall, evidence for APOE e4-associated alterations in Q-Alb and sPDGFRB remained inconclusive, highlighting the need for further study across the spectrum of cognitive ageing and dementia. In contrast, APOE e2 carriage was associated with greater barrier dysfunction as indexed by Q-Alb, broadening the predominant focus on APOE e4 and identifying e2 as a potentially important but understudied contributor to altered neurovascular function.

INTRODUCTION: Whether APOE e4 modifies relationships between subclinical cardiac phenotypes and brain structure is unknown. METHODS: In Framingham Heart Study Offspring participants, we related antecedent echocardiographic remodeling (Examinations 4-6) to repeated brain MRI, and cardiac magnetic resonance phenotypes to regional cortical morphometry, testing cardiac x APOE e4 interactions with false-discovery-rate (FDR) correction and permutation testing of the regional screen. RESULTS: APOE e4 modified the association between antecedent left atrial (LA) remodeling and subsequent lateral ventricular expansion (beta=-0.00858, P=1.45 x 10^-4, q=0.0023; N=1,305; 3,787 MRI observations), the only FDR-significant result of 16 longitudinal tests, including with participant-specific MRI-time slopes (q=0.034); it weakened when intracranial volume x MRI time was modeled. Four regional ventricular cardiac x APOE e4 interactions met within-family FDR criteria, but their number was consistent with chance (permutation P=0.70). Maximum LA volume index showed an APOE e4-dependent association with left middle-occipital cortical-thickness variability (whole-brain q=0.017; permutation P=0.041) that persisted after ventricular adjustment. Cardiac phenotypes and trajectories showed no FDR-significant APOE e4-dependent associations with plasma Abeta42/40, p-tau181, GFAP, or NfL, and adjustment for these biomarkers changed the regional interactions by at most 3.2%. Allen Human Brain Atlas data showed cholesterol-biosynthesis enrichment in the right superior frontal cortex, implicated by the LV end-systolic volume interaction, but without convergent pathway evidence. DISCUSSION: APOE e4 modified atrial-brain relationships, with the strongest evidence linking antecedent atrial remodeling to later ventricular expansion. Replication with prespecified models is needed.

Background: Current recommendations limit the use of menopausal hormone therapy (MHT) principally to the management of menopausal symptoms, largely because of concerns regarding increased breast cancer (BC) risk. The impact of MHT use on systemic biological aging and blood methylome and its overlap with that of menopause timing remains incompletely understood. Methods: In females (N=78,209) of the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial, we used Cox models to assess the associations of menopause timing (ordinal age at menopause; binary early-M [<45 years] vs non-early-M [[&ge;]45 years]) and MHT use with BC incidence, mortality, and survival. In a nested case-control subset with blood DNA methylome (DNAm; 758 cases, 745 controls), we related both exposures to epigenetic clocks and DNAm-based telomere length (DNAmTL) and used polygenic instruments to test both causal directions. Results: Ever MHT use was associated with higher BC incidence (aHR 1.17, 95% CI 1.10-1.24), particularly for hormone-receptor positive (HR+) subtypes (1.19, 1.11-1.27), whereas early-M was associated with lower HR+ incidence (0.88, 0.81-0.96) but not with overall incidence after adjustment (0.94, 0.88-1.01). However, ev-er MHT use was associated with lower BC mortality (0.72, 0.62-0.83) and better overall survival (0.87, 0.81-0.95). In the DNAm subset, non-early-M was associated with slower epigenetic aging and longer DNAmTL par-ticularly in cases. Higher cumulative aging and pace-of-aging markers predicted worse survival and partially mediated the early-M associations. Genetic analyses supported shared polygenic architecture between meno-pause timing and DNAm aging biomarkers rather than simple causation. MHT showed no broad epigenetic age acceleration and its profound methylome and immune-marker signatures largely did not overlap with those of menopause timing. Conclusions: Ever MHT use was associated with lower BC mortality and better overall survival despite higher BC incidence. Systemic aging detected more than a decade after menopausal transition correlates with early menopause. MHT use shows molecular signatures distinct to those seen for menopause timing.

Importance: Long-term exposure to higher average air pollutant concentrations is associated with poorer cognitive health, but annual averages can obscure substantial differences in day-to-day exposure. Whether recurrent high pollution days are associated with long-term cognitive aging trajectories among people with similar overall air pollution exposure is unclear. Objective: To determine whether the annual number of days exceeding World Health Organization daily guideline values for nitrogen dioxide (NO2) and particulate matter (PM2.5 and PM10) is associated with subsequent cognitive decline after accounting for annual mean air pollutant exposure. Design: Prospective cohort study using data from waves 1-10 (2002-03 to 2021-23) of the English Longitudinal Study of Ageing. Setting: Population-based cohort of community-dwelling adults in England. Participants: 12,235 adults aged 50+ years at analytic baseline. Exposures: Number of days exceeding World Health Organization daily guideline values ('exceedance days') for NO2, PM2.5, and PM10, derived from residence-linked environmental estimates during the calendar year preceding the analytic baseline. Main Outcomes and Measures: Baseline cognitive performance and model-estimated 14-year cognitive decline (corresponding to the 75th percentile of follow-up duration) in episodic memory and verbal fluency. Results: Exceedance days were not associated with baseline memory or verbal fluency after adjustment for annual mean air pollutant exposure. More NO2 exceedance days were associated with faster cognitive decline: comparing the 75th percentile with the median of NO2 exceedance days, the difference in 14-year decline was -0.09 SD (95% CI, -0.17 to -0.01; p = 0.02) for memory and -0.10 SD (95% CI, -0.19 to 0.00; p = 0.04) for fluency. PM2.5 and PM10 exceedance days were not associated with cognitive decline. Conclusions and Relevance: In this cohort study of older adults, a higher number of NO2 exceedance days was associated with faster subsequent cognitive decline after adjustment for annual mean air pollutant exposure. This suggests that daily exposure to high NO2 concentrations may be related to accelerated cognitive aging even when offset by lower exposure on other days, potentially providing a new rationale for identifying and prioritizing areas with recurrent high NO2 exposure and the local emission sources contributing to it.

Changes of DNA sequence in the human genome may contribute to human aging, but it has been difficult for the field to define the details of the contribution. Cancer cells have altered ratios of DNA damage and repair pathways, and thus it is inappropriate to utilize them as models for normal cells. Also, somatic mutations from each lineage cannot be clearly identified in cell populations with multiple lineages. Normal human colon crypts are one of the few mini-organ systems where monoclonal cell populations can be found for somatic mutation analysis. In a parallel study, we described complex insertion/deletion (indel) events in normal human colon. Here we focus on simple deletions that lack any nucleotide addition or adjacent base substitutions. We find that ~58% of the simple deletions are consistent with a strand slippage event, and the remainder provide insights into other important repair processes. Among the 4,264 >=2-nucleotide simple deletions, ~71% are most consistent with nonhomologous DNA end joining (NHEJ), with <1.5% of the events being more consistent with alternative end joining (aEJ). The incidence of NHEJ-type simple deletions is ~8-fold more frequent than the complex indels that also show NHEJ features. Similar to the complex indels, the simple deletions show a linear trend of event accumulation (positive slope) with an overall ~10-fold increase in absolute number across the human lifespan, 0.8 months to 90 years old, for individuals with no radiation or chemotherapy treatment. Interestingly, radiation treatment increases non-slippage deletions with little effect on slip deletions.

Background Wearable heart rate (HR) monitors collect minute-level HR continuously across days, yet these data are commonly reduced to scalars such as resting HR (RHR) and heart rate reserve (HRR), defined as the difference between maximum HR and RHR. This discards two dimensions of within-day HR dynamics: how HR range varies across the day and the magnitude and duration of individual HR rises and declines. We introduce diurnal heart rate range (dHRR), a time-of-day-specific measure of HR range across repeated days, and heart rate excursions (HREs), individual HR rises and declines characterized by amplitude and duration. Methods We analyzed minute-level HR from 750 participants in the Baltimore Longitudinal Study of Aging (mean [SD] age, 66 [12] years). We estimated the 5th, 50th, and 95th HR percentiles at each minute of the 24-hour cycle across repeated days, defining diurnal HR (dHR) as the median curve and dHRR as the 95th minus 5th percentile curve. A moving-average algorithm segmented HR into HREs. Function-on-scalar regression modeled dHR and dHRR by age, sex,and BMI across the day; local polynomial regression examined age and sex differences in HRR and HREs. Results Conventional HRR decreased with age, indicating a smaller overall observed HR range. Age-related differences in dHR varied substantially across the day: between ages 40 and 80, fitted dHR was approximately 2 bpm lower at 3:00 AM but 8 bpm lower at 6:00 PM. dHRR showed that this contraction was not uniform across the day: the evening peak near 6:00 PM at younger ages was largely absent by age 70, while the morning peak shifted from approximately 9:00 AM toward noon. At the event level, HREs showed two parallel age-related changes: between ages 40 and 80, mean excursion amplitude decreased from approximately 40 to 32 bpm, while mean excursion duration increased from approximately 90 to 104 minutes. Conclusions Aging was characterized by a smaller global HR range, compression and reorganization of HR range across the day, and smaller, longer-lasting HREs. dHRR and HREs provide complementary views of the diurnal organization and event-level dynamics of wearable HR and are implemented in the open-source ihr R package.

Background Emerging evidence has linked frailty to individual chronic diseases, but whether it predicts a broad disease spectrum and accelerates multimorbidity accumulation over time remains unknown. This study aimed to systematically evaluate the associations of physical frailty with the burden of incident disease across a wide range of chronic conditions, and with the long-term rates of multimorbidity accumulation. Methods In this prospective cohort study of 466,864 UK Biobank participants , frailty status was assessed using the Fried frailty phenotype and categorized as robust, pre-frailty, or frailty. Chronic diseases were defined based on International Classification of Diseases (ICD)-10 codes, and disease patterns were identified using network analysis. Cox proportional hazards models were used to examine the associations of frailty status with incident chronic diseases, and linear mixed models were used to assess the annual rate of chronic disease accumulation. Results During a median follow-up of 13.8 years (IQR: 13.1-14.5), 536 incident chronic diseases across multiple systems were recorded. Physical frailty was associated with a significantly increased risk of 458 incident diseases (Bonferroni-corrected P < 0.05/536). In the overall cohort, compared with robust participants, those with pre-frailty ({beta} = 0.266, 95% confidence interval [CI]: 0.264-0.267) and frailty ({beta} = 0.941, 95% CI: 0.936-0.946) exhibited significantly faster rates of multimorbidity accumulation. This accelerated multimorbidity accumulation was consistently observed across strata of baseline disease burden, including participant with 0 ({beta} = 0.644, 95% CI: 0.635-0.653), 1 ({beta} =0.748, 95% CI: 0.727-0.768), [&ge;] 2 ({beta} =0.940, 95% CI: 0.933-0.947) chronic conditions at baseline. Similar associations were also found across distinct disease patterns, including neurodegenerative, metabolic, and psychiatric patterns. Conclusions Physical frailty predicts a broad range of incident diseases and is associated with accelerated multimorbidity accumulation. Incorporating frailty assessment into prevention strategies may help mitigate the growing burden of multimorbidity.

The effects of older age on the oxidation of energy substrates (carbohydrates, fats) over 24 hr and during activities of daily living (ADL) may have substantial implications for metabolic health. To examine this issue, we evaluated age-related differences in substrate oxidation for 24 hr and periods of sleep, ADLs, and a 30-min treadmill walk (30MTW, 1.3m{middle dot}s^-1) in 17 young (29 {+/-} 5 yr, mean {+/-} SD, 6F) and 16 older (72 {+/-} 5, 8F) healthy active adults. Oxygen consumption (&VdotO2) and carbon dioxide production were measured using a 32,500 L room calorimeter to quantify substrate oxidation, which was normalized to body mass (kJ{middle dot}kg^-1) and total energy expenditure (%). Separately, &VdotO2peak was measured during an incremental treadmill test to exhaustion. &VdotO2peak (ml{middle dot}kg^-1{middle dot}min^-1) was lower in older adults compared with young adults. Older adults oxidized fewer carbohydrates than young over 24 hr (kJ{middle dot}kg^-1, %), sleep (kJ{middle dot}kg^-1), and ADLs (kJ{middle dot}kg^-1, %); and fat oxidation was greater in older than young over 24 hr (kJ{middle dot}kg^-1, %) and ADLs (kJ{middle dot}kg^-1, %). Carbohydrate oxidation did not differ by group during the 30MTW (kJ{middle dot}kg^-1, %), but fat oxidation was greater in older (kJ{middle dot}kg^-1) despite their walking at a greater relative intensity. These results indicate that older adults derived oxidative energy differently than young over 24 hr and during daily tasks. The lower carbohydrate and greater fat contribution to daily energy requirements may be meaningful in the development of metabolic disease in older adults.