The Health, Aging, and Body Composition (Health ABC) Study-Ground-Breaking Science for 25 Years and Counting

BACKGROUND

The Health, Aging, and Body Composition Study is a longitudinal cohort study that started just over 25 years ago. This ground-breaking study tested specific hypotheses about the importance of weight, body composition, and weight-related health conditions for incident functional limitation in older adults.

METHODS

Narrative review with analysis of ancillary studies, career awards, publications, and citations.

RESULTS

Key findings of the study demonstrated the importance of body composition as a whole, both fat and lean mass, in the disablement pathway. The quality of the muscle in terms of its strength and its composition was found to be a critical feature in defining sarcopenia. Dietary patterns and especially protein intake, social factors, and cognition were found to be critical elements for functional limitation and disability. The study is highly cited and its assessments have been widely adopted in both observational studies and clinical trials. Its impact continues as a platform for collaboration and career development.

CONCLUSIONS

The Health ABC provides a knowledge base for the prevention of disability and promotion of mobility in older adults.

Weight variability, physical functioning and incident disability in older adults

BACKGROUND

This study aimed to determine if greater variability in body mass index (BMI) is associated with declines in physical functioning and incident disability in older adults.

METHODS

Included were participants from the Health, Aging and Body Composition Study who had semi-annual BMI data during the first 3 years of follow-up. Participants were categorized into quintiles of BMI variability, using two methods. The first method used average successive variability, whereas the second method adjusted these values to remove the variability due to net change in BMI over the 3-year period. Linear regression was used to assess the relationship between the two measures of BMI variability and net changes in BMI, fat mass index, appendicular lean mass index, and Health, Aging and Body Composition Physical Performance Score during the first 3 years of the study. Cox proportional hazard models were used to assess the relationship of BMI variability with the subsequent incidence of new disability, adjusting for confounding factors.

RESULTS

Among 2121 participants, those in the highest BMI variability quintile were more likely to lose both body mass (β: -0.086 [95% confidence interval, CI: -0.133, -0.040], P < 0.01) and fat mass (β: -0.059 [95% CI: -0.117, -0.002], P = 0.04) and had greater declines in physical performance score (β: -0.094 [95% CI: -0.162, -0.026], P < 0.01) compared to participants with the least variability in BMI. Participants with high BMI variability also had higher rates of incident disability (hazard ratio: 1.36 [95% CI: 1.07, 1.72], P = 0.01), independent of net BMI change.

CONCLUSIONS

BMI variability in older adults is associated with decline in physical performance and incident disability. This relationship cannot be explained by net weight loss alone, supporting it as an independent feature of frailty.

Circulating serum microRNAs including senescent miR-31-5p are associated with incident fragility fractures in older postmenopausal women with type 2 diabetes mellitus

Fragility fractures are an important hallmark of aging and an increasingly recognized complication of Type 2 diabetes (T2D). T2D individuals have been found to exhibit an increased fracture risk despite elevated bone mineral density (BMD) by dual x-ray absorptiometry (DXA). However, BMD and FRAX-scores tend to underestimate fracture risk in T2D. New, reliable biomarkers are therefore needed. MicroRNAs (miRNAs) are secreted into the circulation from cells of various tissues proportional to local disease severity. Serum miRNA-classifiers were recently found to discriminate T2D women with and without prevalent fragility fractures with high specificity and sensitivity (AUC > 0.90). However, the association of circulating miRNAs with incident fractures in T2D has not been examined yet. In 168 T2D postmenopausal women in the AGES-Reykjavik cohort, miRNAs were extracted from baseline serum and a panel of 10 circulating miRNAs known to be involved in diabetic bone disease and aging was quantified by qPCR and Ct-values extracted. Unadjusted and adjusted Cox proportional hazard models assessed the associations between serum miRNAs and incident fragility fracture. Additionally, Receiver operating curve (ROC) analyses were performed. Of the included 168 T2D postmenopausal women who were on average 77.2 ± 5.6 years old, 70 experienced at least one incident fragility fracture during the mean follow-up of 5.8 ± 2.7 years. We found that 3 serum miRNAs were significantly associated with incident diabetic fragility fracture: while low expression of miR-19b-1-5p was associated with significantly lower risk of incident fragility fracture (HR 0.84 (95% CI: 0.71-0.99, p = 0.0323)), low expression of miR-203a and miR-31-5p was each significantly associated with a higher risk of incident fragility fracture per unit increase in Ct-value (miR-203a: HR 1.29 (95% CI: 1.12-1.49), p = 0.0004, miR-31-5p HR 1.27 (95% CI: 1.06-1.52), p = 0.009). Hazard ratios of the latter two miRNAs remained significant after adjustments for age, body mass index (BMI), areal bone mineral density (aBMD), clinical FRAX or FRAXaBMD. Women with miR-203a and miR-31-5p serum levels in the lowest expression quartiles exhibited a 2.4-3.4-fold larger fracture risk than women with miR-31-5p and miR-203a serum expressions in the highest expression quartile (0.002 ≤ p ≤ 0.039). Women with both miR-203a and miR-31-5p serum levels below the median had a significantly increased fracture risk (Unadjusted HR 3.26 (95% CI: 1.57-6.78, p = 0.001) compared to those with both expression levels above the median, stable to adjustments. We next built a diabetic fragility signature consisting of the 3 miRNAs that showed the largest associations with incident fracture (miR-203a, miR-31-5p, miR-19b-1-5p). This 3-miRNA signature showed with an AUC of 0.722 comparable diagnostic accuracy in identifying incident fractures to any of the clinical parameters such as aBMD, Clinical FRAX or FRAXaBMD alone. When the 3 miRNAs were combined with aBMD, this combined 4-feature signature performed with an AUC of 0.756 (95% CI: 0.680, 0.823) significantly better than aBMD alone (AUC 0.666, 95% CI: 0.585, 0.741) (p = 0.009). Our data indicate that specific serum microRNAs including senescent miR-31-5p are associated with incident fragility fracture in older diabetic women and can significantly improve fracture risk prediction in diabetics when combined with aBMD measurements of the femoral neck.

A Metabolite Composite Score Attenuated a Substantial Portion of the Higher Mortality Risk Associated With Frailty Among Community-Dwelling Older Adults

BACKGROUND

Frailty is more prevalent among black versus white older Americans. We previously identified 37 metabolites associated with the vigor to frailty spectrum using the Scale of Aging Vigor in Epidemiology (SAVE) among older black men from the Health, Aging, and Body Composition (Health ABC) study. Here, we sought to develop a metabolite composite score based on the 37 SAVE-associated metabolites and determine whether the composite score predicts mortality and whether it attenuates the association between frailty and mortality among older black men.

METHODS

Plasma metabolites were measured using liquid chromatography-mass spectrometry. Most of the 37 metabolites were organic acids/derivatives or lipids. Metabolites were ranked into tertiles: tertiles associated with more vigorous SAVE scores were scored 0, mid-tertiles were scored 1, and tertiles associated with frailer SAVE scores were scored 2. Composite scores were the sum of metabolite tertile scores. We examined mortality associations using Cox regression. Percent attenuation estimated the extent to which metabolites attenuated the association between frailty and mortality.

RESULTS

One standard deviation frailer SAVE was associated with 30% higher mortality, adjusting for age and site (p = .0002); this association was attenuated by 56% after additionally adjusting for the metabolite composite score. In this model, one standard deviation higher metabolite composite score was associated with 46% higher mortality (p < .0001). Metabolite composite scores also predicted mortality (p = .045) in a validation sample of 120 older adults (40% men, 90% white).

CONCLUSION

These metabolites may provide a deeper characterization of the higher mortality that is associated with frailty among older adults.

Publisher Correction: A meta-analysis of genome-wide association studies identifies multiple longevity genes

A Correction to this paper has been published: https://doi.org/10.1038/s41467-021-22613-2

Computed tomography-based skeletal muscle and adipose tissue attenuation: Variations by age, sex, and muscle

OBJECTIVE

This study aimed to investigate how skeletal muscle attenuation and adipose tissue (AT) attenuation of the quadriceps, hamstrings, paraspinal muscle groups and the psoas muscle vary according to the targeted muscles, sex, and age.

DESIGN

Population-based cross-sectional study.

SETTING

Community-dwelling old population in Reykjavik, Iceland.

SUBJECTS

A total of 5331 older adults (42.8% women), aged 66-96 years from the Age, Gene/Environment Susceptibility (AGES)- Reykjavik Study, who participated in the baseline visit (between 2002 and 2006) and had valid thigh and abdominal computed tomography (CT) scans were studied.

METHODS

Muscle attenuation and AT attenuation of the quadriceps, hamstrings, paraspinal muscle groups and the psoas muscle were determined using CT. Linear mixed model analysis of variance was performed for each sex, with skeletal muscle or AT attenuation as the dependent variable.

RESULTS

Muscle attenuation decreased, and AT attenuation increased with age in both sexes, and these differences were specific for each muscle, although not in all age groups. Age-related differences in muscle and AT attenuation varied with specific muscle. In general, for both sexes, skeletal muscle attenuation of the hamstrings declined more than average with age. Men and women displayed a different pattern in the age differences in AT attenuation for each muscle.

CONCLUSIONS

Our data support the hypotheses that skeletal muscle attenuation decreases, and AT attenuation increases with aging. In addition, our data add new evidence, supporting that age-related differences in skeletal muscle and AT attenuation vary between muscles.

A Meta-Analysis of the Transferability of Bone Mineral Density Genetic Loci Associations From European to African Ancestry Populations

Genetic studies of bone mineral density (BMD) largely have been conducted in European populations. We therefore conducted a meta-analysis of six independent African ancestry cohorts to determine whether previously reported BMD loci identified in European populations were transferable to African ancestry populations. We included nearly 5000 individuals with both genetic data and assessments of BMD. Genotype imputation was conducted using the 1000G reference panel. We assessed single-nucleotide polymorphism (SNP) associations with femoral neck and lumbar spine BMD in each cohort separately, then combined results in fixed effects (or random effects if study heterogeneity was high, I2 index >60) inverse variance weighted meta-analyses. In secondary analyses, we conducted locus-based analyses of rare variants using SKAT-O. Mean age ranged from 12 to 68 years. One cohort included only men and another cohort included only women; the proportion of women in the other four cohorts ranged from 52% to 63%. Of 56 BMD loci tested, one locus, 6q25 (C6orf97, p = 8.87 × 10-4 ), was associated with lumbar spine BMD and two loci, 7q21 (SLC25A13, p = 2.84 × 10-4 ) and 7q31 (WNT16, p = 2.96 × 10-5 ), were associated with femoral neck BMD. Effects were in the same direction as previously reported in European ancestry studies and met a Bonferroni-adjusted p value threshold, the criteria for transferability to African ancestry populations. We also found associations that met locus-specific Bonferroni-adjusted p value thresholds in 11q13 (LRP5, p < 2.23 × 10-4 ), 11q14 (DCDC5, p < 5.35 × 10-5 ), and 17p13 (SMG6, p < 6.78 × 10-5 ) that were not tagged by European ancestry index SNPs. Rare single-nucleotide variants in AKAP11 (p = 2.32 × 10-2 ), MBL2 (p = 4.09 × 10-2 ), MEPE (p = 3.15 × 10-2 ), SLC25A13 (p = 3.03 × 10-2 ), STARD3NL (p = 3.35 × 10-2 ), and TNFRSF11A (p = 3.18 × 10-3 ) were also associated with BMD. The majority of known BMD loci were not transferable. Larger genetic studies of BMD in African ancestry populations will be needed to overcome limitations in statistical power and to identify both other loci that are transferable across populations and novel population-specific variants. © 2020 American Society for Bone and Mineral Research (ASBMR).

Olfaction and Changes in Body Composition in a Large Cohort of Older U.S. Adults

BACKGROUND

Poor sense of smell in older adults may lead to weight loss, which may further contribute to various adverse health outcomes. However, empirical prospective evidence is lacking. We aimed to longitudinally assess whether poor olfaction is associated with changes in body composition among older adults.

METHODS

A total of 2,390 participants from the Health ABC Study had their olfaction assessed using the Brief Smell Identification Test in 1999-2000. Based on the test score, olfaction was defined as poor (0-8), moderate (9-10), or good (11-12). Total body mass, lean mass, and fat mass were measured by dual-energy X-ray absorptiometry annually or biennially from 1999 to 2007.

RESULTS

At baseline, compared to participants with good olfaction, those with poor olfaction weighed on average 1.67 kg less (95% CI: -2.92, -0.42) in total mass, 0.53 kg less (95% CI: -1.08, 0.02) in lean mass, and 1.14 kg less (95% CI: -1.96, -0.31) in fat mass. In longitudinal analyses, compared to participants with good olfaction, those with poor olfaction had a greater annual decline in both total mass (-234 g, 95% CI: -442, -26) and lean mass (-139 g, 95% CI: -236, -43). They also tended to have a greater annual loss of fat mass (-113 g, 95% CI: -285, 59), but the difference was not statistically significant.

CONCLUSIONS

Our results indicate poor olfaction is associated with lower body weight and greater weight loss in older adults. It is imperative for future studies to investigate potential underlying mechanisms and associated adverse health consequences.

A Noncoding Variant Near PPP1R3B Promotes Liver Glycogen Storage and MetS, but Protects Against Myocardial Infarction

CONTEXT

Glycogen storage diseases are rare. Increased glycogen in the liver results in increased attenuation.

OBJECTIVE

Investigate the association and function of a noncoding region associated with liver attenuation but not histologic nonalcoholic fatty liver disease.

DESIGN

Genetics of Obesity-associated Liver Disease Consortium.

SETTING

Population-based.

MAIN OUTCOME

Computed tomography measured liver attenuation.

RESULTS

Carriers of rs4841132-A (frequency 2%-19%) do not show increased hepatic steatosis; they have increased liver attenuation indicative of increased glycogen deposition. rs4841132 falls in a noncoding RNA LOC157273 ~190 kb upstream of PPP1R3B. We demonstrate that rs4841132-A increases PPP1R3B through a cis genetic effect. Using CRISPR/Cas9 we engineered a 105-bp deletion including rs4841132-A in human hepatocarcinoma cells that increases PPP1R3B, decreases LOC157273, and increases glycogen perfectly mirroring the human disease. Overexpression of PPP1R3B or knockdown of LOC157273 increased glycogen but did not result in decreased LOC157273 or increased PPP1R3B, respectively, suggesting that the effects may not all occur via affecting RNA levels. Based on electronic health record (EHR) data, rs4841132-A associates with all components of the metabolic syndrome (MetS). However, rs4841132-A associated with decreased low-density lipoprotein (LDL) cholesterol and risk for myocardial infarction (MI). A metabolic signature for rs4841132-A includes increased glycine, lactate, triglycerides, and decreased acetoacetate and beta-hydroxybutyrate.

CONCLUSIONS

These results show that rs4841132-A promotes a hepatic glycogen storage disease by increasing PPP1R3B and decreasing LOC157273. rs4841132-A promotes glycogen accumulation and development of MetS but lowers LDL cholesterol and risk for MI. These results suggest that elevated hepatic glycogen is one cause of MetS that does not invariably promote MI.

Multi-Ancestry Genome-wide Association Study Accounting for Gene-Psychosocial Factor Interactions Identifies Novel Loci for Blood Pressure Traits

Psychological and social factors are known to influence blood pressure (BP) and risk of hypertension and associated cardiovascular diseases. To identify novel BP loci, we carried out genome-wide association meta-analyses of systolic, diastolic, pulse, and mean arterial BP taking into account the interaction effects of genetic variants with three psychosocial factors: depressive symptoms, anxiety symptoms, and social support. Analyses were performed using a two-stage design in a sample of up to 128,894 adults from 5 ancestry groups. In the combined meta-analyses of Stages 1 and 2, we identified 59 loci (p value <5e-8), including nine novel BP loci. The novel associations were observed mostly with pulse pressure, with fewer observed with mean arterial pressure. Five novel loci were identified in African ancestry, and all but one showed patterns of interaction with at least one psychosocial factor. Functional annotation of the novel loci supports a major role for genes implicated in the immune response (PLCL2), synaptic function and neurotransmission (LIN7A, PFIA2), as well as genes previously implicated in neuropsychiatric or stress-related disorders (FSTL5, CHODL). These findings underscore the importance of considering psychological and social factors in gene discovery for BP, especially in non-European populations.

Sex-dimorphic genetic effects and novel loci for fasting glucose and insulin variability

Differences between sexes contribute to variation in the levels of fasting glucose and insulin. Epidemiological studies established a higher prevalence of impaired fasting glucose in men and impaired glucose tolerance in women, however, the genetic component underlying this phenomenon is not established. We assess sex-dimorphic (73,089/50,404 women and 67,506/47,806 men) and sex-combined (151,188/105,056 individuals) fasting glucose/fasting insulin genetic effects via genome-wide association study meta-analyses in individuals of European descent without diabetes. Here we report sex dimorphism in allelic effects on fasting insulin at IRS1 and ZNF12 loci, the latter showing higher RNA expression in whole blood in women compared to men. We also observe sex-homogeneous effects on fasting glucose at seven novel loci. Fasting insulin in women shows stronger genetic correlations than in men with waist-to-hip ratio and anorexia nervosa. Furthermore, waist-to-hip ratio is causally related to insulin resistance in women, but not in men. These results position dissection of metabolic and glycemic health sex dimorphism as a steppingstone for understanding differences in genetic effects between women and men in related phenotypes.

Association between 25-Hydroxyvitamin D and Metabolic Syndrome in Older Adults: The Health, Aging and Body Composition Study

OBJECTIVE

Low 25-hydroxyvitamin D (25[OH]D) levels and metabolic syndrome (MetS) are prevalent among older adults; however, longitudinal studies examining 25(OH)D status and MetS are lacking. We explore the association of 25(OH)D levels with prevalent and incident MetS in white and black older adults. Research Design and Methods. A total of 1620 white and 1016 black participants aged 70-79 years from the Health ABC cohort with measured 25(OH)D levels and data on MetS and covariates of interest were examined. The association between 25(OH)D levels and prevalent MetS at baseline and incident MetS at 6-year follow-up was examined in whites and blacks separately using logistic regression adjusting for demographics, lifestyle factors, and renal function.

RESULTS

At baseline, 635 (39%) white and 363 (36%) black participants had prevalent MetS. In whites, low 25(OH)D levels were associated with prevalent MetS (adjusted OR (95% CI), 1.85 (1.47, 2.34)) and 1.96 (1.46, 2.63) for 25(OH)D of 20-<30 and <20 vs. ≥30 ng/ml, respectively). The association was attenuated after adjustment for BMI but remained significant. No association was found between 25(OH)D levels and prevalent MetS in blacks. Among those without MetS at baseline (765 whites, 427 blacks), 150 (20%) whites and 87 (20%) blacks had developed MetS at 6-year follow-up. However, 25(OH)D levels were not associated with incident MetS in whites or blacks.

CONCLUSION

In older adults, low 25(OH)D levels were associated with increased odds of prevalent MetS in whites but not in blacks. No association was observed between 25(OH)D levels and incident MetS in either whites or blacks.

Discovery of rare variants associated with blood pressure regulation through meta-analysis of 1.3 million individuals

Genetic studies of blood pressure (BP) to date have mainly analyzed common variants (minor allele frequency > 0.05). In a meta-analysis of up to ~1.3 million participants, we discovered 106 new BP-associated genomic regions and 87 rare (minor allele frequency ≤ 0.01) variant BP associations (P < 5 × 10-8), of which 32 were in new BP-associated loci and 55 were independent BP-associated single-nucleotide variants within known BP-associated regions. Average effects of rare variants (44% coding) were ~8 times larger than common variant effects and indicate potential candidate causal genes at new and known loci (for example, GATA5 and PLCB3). BP-associated variants (including rare and common) were enriched in regions of active chromatin in fetal tissues, potentially linking fetal development with BP regulation in later life. Multivariable Mendelian randomization suggested possible inverse effects of elevated systolic and diastolic BP on large artery stroke. Our study demonstrates the utility of rare-variant analyses for identifying candidate genes and the results highlight potential therapeutic targets.

Genetic Studies of Leptin Concentrations Implicate Leptin in the Regulation of Early Adiposity

Leptin influences food intake by informing the brain about the status of body fat stores. Rare LEP mutations associated with congenital leptin deficiency cause severe early-onset obesity that can be mitigated by administering leptin. However, the role of genetic regulation of leptin in polygenic obesity remains poorly understood. We performed an exome-based analysis in up to 57,232 individuals of diverse ancestries to identify genetic variants that influence adiposity-adjusted leptin concentrations. We identify five novel variants, including four missense variants, in LEP, ZNF800, KLHL31, and ACTL9, and one intergenic variant near KLF14. The missense variant Val94Met (rs17151919) in LEP was common in individuals of African ancestry only, and its association with lower leptin concentrations was specific to this ancestry (P = 2 × 10^-16, n = 3,901). Using in vitro analyses, we show that the Met94 allele decreases leptin secretion. We also show that the Met94 allele is associated with higher BMI in young African-ancestry children but not in adults, suggesting that leptin regulates early adiposity.

Cigarette Smoking Is Associated With Lower Quadriceps Cross-sectional Area and Attenuation in Older Adults

INTRODUCTION

In addition to well-established links with cardiovascular and respiratory diseases, cigarette smoking may affect skeletal muscle; however, associations with quadriceps atrophy, density, and function are unknown. This study explored the associations of current and former smoking with quadriceps muscle area and attenuation as well as muscle force (assessed as knee extension peak torque) and rate of torque development-a measure of muscle power in older adults.

METHODS

Data from 4469 older adults, aged 66-95 years at baseline in the Age, Gene/Environment Susceptibility-Reykjavik Study with measurements of thigh computed tomography, isometric knee extension testing, self-reported smoking history, and potential covariates were analyzed.

RESULTS

Sex differences were observed in these data; therefore, our final analyses are stratified by sex. In men, both former smokers and current smokers had lower muscle area (with β= -0.10, 95% confidence interval [CI] = -0.17 to -0.03 and β = -0.19, 95% CI = -0.33 to -0.05, respectively) and lower muscle attenuation (ie, higher fat infiltration, β = -0.08, 95% CI = -0.16 to -0.01 and β = -0.17, 95% CI = -0.34 to -0.01, respectively) when compared with never smokers. Smoking status was not associated with male peak torque or rate of torque development. In women, current smoking was associated with lower muscle attenuation (β = -0.24, 95% CI = -0.34 to -0.13) compared to never smoking. Among female smokers (current and former), muscle attenuation and peak torque were lower with increasing pack-years.

CONCLUSIONS

Results suggest that cigarette smoking is related to multiple muscle properties at older age and that these relationships may be different among men and women.

IMPLICATIONS

This article presents novel data, as it examined for the first time the relationship between smoking and computed tomography-derived quadriceps muscle size (cross-sectional area) and attenuation. This study suggests that current cigarette smoking is related to higher muscle fat infiltration, which may have significant health implications for the older population, because of its known association with poor physical function, falls, and hip fractures.

Multi-ancestry GWAS of the electrocardiographic PR interval identifies 202 loci underlying cardiac conduction

The electrocardiographic PR interval reflects atrioventricular conduction, and is associated with conduction abnormalities, pacemaker implantation, atrial fibrillation (AF), and cardiovascular mortality. Here we report a multi-ancestry (N = 293,051) genome-wide association meta-analysis for the PR interval, discovering 202 loci of which 141 have not previously been reported. Variants at identified loci increase the percentage of heritability explained, from 33.5% to 62.6%. We observe enrichment for cardiac muscle developmental/contractile and cytoskeletal genes, highlighting key regulation processes for atrioventricular conduction. Additionally, 8 loci not previously reported harbor genes underlying inherited arrhythmic syndromes and/or cardiomyopathies suggesting a role for these genes in cardiovascular pathology in the general population. We show that polygenic predisposition to PR interval duration is an endophenotype for cardiovascular disease, including distal conduction disease, AF, and atrioventricular pre-excitation. These findings advance our understanding of the polygenic basis of cardiac conduction, and the genetic relationship between PR interval duration and cardiovascular disease.

Smoking-by-genotype interaction in type 2 diabetes risk and fasting glucose

Smoking is a potentially causal behavioral risk factor for type 2 diabetes (T2D), but not all smokers develop T2D. It is unknown whether genetic factors partially explain this variation. We performed genome-environment-wide interaction studies to identify loci exhibiting potential interaction with baseline smoking status (ever vs. never) on incident T2D and fasting glucose (FG). Analyses were performed in participants of European (EA) and African ancestry (AA) separately. Discovery analyses were conducted using genotype data from the 50,000-single-nucleotide polymorphism (SNP) ITMAT-Broad-CARe (IBC) array in 5 cohorts from from the Candidate Gene Association Resource Consortium (n = 23,189). Replication was performed in up to 16 studies from the Cohorts for Heart Aging Research in Genomic Epidemiology Consortium (n = 74,584). In meta-analysis of discovery and replication estimates, 5 SNPs met at least one criterion for potential interaction with smoking on incident T2D at p<1x10-7 (adjusted for multiple hypothesis-testing with the IBC array). Two SNPs had significant joint effects in the overall model and significant main effects only in one smoking stratum: rs140637 (FBN1) in AA individuals had a significant main effect only among smokers, and rs1444261 (closest gene C2orf63) in EA individuals had a significant main effect only among nonsmokers. Three additional SNPs were identified as having potential interaction by exhibiting a significant main effects only in smokers: rs1801232 (CUBN) in AA individuals, rs12243326 (TCF7L2) in EA individuals, and rs4132670 (TCF7L2) in EA individuals. No SNP met significance for potential interaction with smoking on baseline FG. The identification of these loci provides evidence for genetic interactions with smoking exposure that may explain some of the heterogeneity in the association between smoking and T2D.

Plasma Soluble αKlotho, Serum Fibroblast Growth Factor 23, and Mobility Disability in Community-Dwelling Older Adults

CONTEXT

αKlotho is a hormone and co-receptor for fibroblast growth factor 23 (FGF23), a hormone that downregulates active vitamin D synthesis and promotes phosphate excretion. Low αKlotho and high FGF23 occur in chronic kidney disease (CKD).

OBJECTIVE

We aimed to assess the relationships of αKlotho and FGF23 with mobility disability in community-dwelling older adults.

DESIGN AND SETTING

We estimated associations of plasma-soluble αKlotho and serum FGF23 concentrations with mobility disability over 6 years. Additional analyses was stratified by CKD.

PARTICIPANTS

Participants included 2751 adults (25.0% with CKD), aged 71 to 80 years, from the 1998 to 1999 Health, Aging, and Body Composition Study visit.

MAIN OUTCOME MEASURES

Walking disability and stair climb disability were defined as self-reported "a lot of difficulty" or an inability to walk a quarter mile and climb 10 stairs, respectively.

RESULTS

Median (interquartile range [IQR]) serum FGF23 and plasma soluble αKlotho concentrations were 46.6 (36.7, 60.2) pg/mL and 630.4 (478.4, 816.0) pg/mL, respectively. After adjustment, higher αKlotho concentrations were associated with lower walking disability rates (Rate Ratio [RR] highest vs. lowest tertile = 0.74; 95% confidence interval l [CI] = 0.62, 0.89; P = 0.003). Higher FGF23 concentrations were associated with higher walking disability rates (RR highest vs. lowest tertile = 1.24; 95%CI = 1.03, 1.50; P = 0.005). Overall, higher αKlotho combined with lower FGF23 was associated with the lowest walking disability rates (P for interaction = 0.023). Stair climb disability findings were inconsistent. No interactions with CKD were statistically significant (P for interaction > 0.10).

CONCLUSIONS

Higher plasma soluble αKlotho and lower serum FGF23 concentrations were associated with lower walking disability rates in community-dwelling older adults, particularly those without CKD.

Associations between novel jump test measures, grip strength, and physical performance: the Osteoporotic Fractures in Men (MrOS) Study

BACKGROUND/AIMS

Weight-bearing jump tests measure lower extremity muscle power, velocity, and force, and may be more strongly related to physical performance than grip strength. However, these relationships are not well described in older adults.

METHODS

Participants were 1242 older men (mean age 84 ± 4 years) in the Osteoporotic Fractures in Men (MrOS) Study. Jump peak power (Watts/kg body weight), force (Newton/kg body weight) at peak power, and velocity (m/s) at peak power were measured by jump tests on a force plate. Grip strength (kg/kg body weight) was assessed by hand-held dynamometry. Physical performance included 400 m walk time (s), 6 m usual gait speed (m/s), and 5-repeated chair stands speed (#/s).

RESULTS

In adjusted Pearson correlations, power/kg and velocity moderately correlated with all performance measures (range r = 0.41-0.51; all p < 0.001), while correlations for force/kg and grip strength/kg were weaker (range r = 0.20-0.33; all p < 0.001). Grip strength/kg moderately correlated with power/kg (r = 0.44; p < 0.001) but not velocity or force/kg. In adjusted linear regression with standardized βs, 1 SD lower power/kg was associated with worse: 400 m walk time (β = 0.47), gait speed (β = 0.42), and chair stands speed (β = 0.43) (all p < 0.05). Associations with velocity were similar (400 m walk time: β = 0.42; gait speed: β = 0.38; chair stands speed: β = 0.37; all p < 0.05). Force/kg and grip strength/kg were more weakly associated with performance (range β = 0.18-0.28; all p < 0.05).

CONCLUSIONS/DISCUSSION

Jump power and velocity had stronger associations with physical performance than jump force or grip strength. This suggests lower extremity power and velocity may be more strongly related to physical performance than lower extremity force or upper extremity strength in older men.

Mortality in Relation to Changes in a Healthy Aging Index: The Health, Aging, and Body Composition Study

BACKGROUND

Baseline scores on a Healthy Aging Index (HAI), including five key physiologic domains, strongly predict health outcomes. This study aimed to characterize 9-year changes in a HAI and explore their relationship to subsequent mortality.

METHODS

Data are from the Health, Aging, and Body Composition study of well-functioning adults aged 70-79 years. A HAI, which ranges from 0 to 10, was constructed at years 1 and 10 of the study including systolic blood pressure, forced expiratory volume, digit symbol substitution test, cystatin C, and fasting glucose. The relationships between the HAI at years 1 and 10 and the change between years and subsequent mortality until year 17 were estimated from Cox proportional hazards models.

RESULTS

Two thousand two hundred sixty-four participants had complete data on a HAI at year 1, of these 1,122 had complete data at year 10. HAI scores tended to increase (i.e. get worse) over 9-year follow-up, from (mean [SD]) 4.3 (2.1) to 5.7 (2.1); mean within-person change 1.5 (1.6). After multivariable adjustment, HAI score was related to mortality from year 1 (hazard ratio [95% confidence interval] = 1.17 [1.13-1.21] per unit) and year 10 (1.20 [1.14-1.27] per unit). The change between years was also related to mortality (1.08 [1.02-1.15] per unit change).

CONCLUSIONS

HAI scores tended to increase with advancing age and stratified mortality rates among participants remaining at year 10. The HAI may prove useful to understand changes in health with aging.

Greater Bone Marrow Adiposity Predicts Bone Loss in Older Women

Bone marrow adiposity (BMA) is associated with aging and osteoporosis, but whether BMA can predict bone loss and fractures remains unknown. Using data from the Age Gene/Environment Susceptibility (AGES)-Reykjavik study, we investigated the associations between ¹ H-MRS-based measures of vertebral bone marrow adipose tissue (BMAT), annualized change in bone density/strength by quantitative computed tomography (QCT) and DXA, and secondarily, with incident clinical fractures and radiographic vertebral fractures among older adults. The associations between BMAT and annualized change in bone density/strength were evaluated using linear regression models, adjusted for age, body mass index (BMI), diabetes, estradiol, and testosterone. Cox proportional hazards models were used to evaluate the associations between baseline BMAT and incident clinical fractures, and logistic regression models for incident vertebral fractures. At baseline, mean ± SD age was 80.9 ± 4.2 and 82.6 ± 4.2 years in women (n = 148) and men (n = 150), respectively. Mean baseline BMAT was 55.4% ± 8.1% in women and 54.1% ± 8.2% in men. Incident clinical fractures occurred in 7.4% of women over 2.8 years and in 6.0% of men over 2.2 years. Incident vertebral fractures occurred in 12% of women over 3.3 years and in 17% of men over 2.7 years. Each 1 SD increase in baseline BMAT was associated with a 3.9 mg² /cm⁴ /year greater loss of spine compressive strength index (p value = .003), a 0.9 mg/cm³ /year greater loss of spine trabecular BMD (p value = .02), and a 1.2 mg/cm³ /year greater loss of femoral neck trabecular BMD (p value = .02) in women. Among men, there were no associations between BMAT and changes in bone density/strength. There were no associations between BMAT and incident fractures in women or men. In conclusion, we found greater BMAT is associated with greater loss of trabecular bone at the spine and femoral neck, and greater loss of spine compressive strength, in older women. © 2019 American Society for Bone and Mineral Research.

Childhood overweight and obesity and the risk of depression across the lifespan

BACKGROUND

Obesity has been longitudinally associated with depression but only few studies take a life course approach. This longitudinal study investigates whether being overweight or obese at age 8 and 13 years is associated with depressive symptoms more than 60 years later and whether this association is independent of late-life body mass index (BMI). We also investigated the association of being overweight/obese at age 8 or 13 years with ever having major depressive disorder (lifetime MDD).

METHOD

This analysis is based on a sub-sample of 889 AGES-Reykjavik participants with measured BMI data from early life. Late-life depressive symptoms were measured with the Geriatric Depression Scale (GDS) and lifetime MDD was assessed at late-life using the Mini International Neuropsychiatric Interview. Logistic regression analysis was used to estimate the relationships between BMI (continuous and categorical) at age 8 or 13 years, and late-life depressive symptoms (measured as GDS ≥ 5) or lifetime MDD, adjusted for sex, education, physical activity, smoking status and alcohol use. In a separate model, additional adjustments were made for late-life BMI.

RESULTS

One hundred and one subjects (11%) had depressive symptoms at late-life (GDS ≥ 5), and 39 subjects (4.4%) had lifetime MDD. Being overweight or obese at age 8 or 13 years was not associated with higher depressive symptoms during late-life, irrespective of late-life BMI. Being overweight or obese at age 8 years, but not age 13 years was associated with an increased risk of lifetime MDD (Odds Ratio (OR) (95% confidence interval [CI]) for age 8 = 4.03[1.16-13.96]P = 0.03 and age 13 = 2.65[0.69-10.26] P = 0.16, respectively).

CONCLUSION

Being overweight in childhood was associated with increased odds of lifetime MDD, although the magnitude of the risk is uncertain given the small numbers of participants with lifetime MDD. No clear association was observed between childhood and adolescent overweight/obesity and late-life depressive symptoms irrespective of late life BMI.

Chronic kidney disease and peripheral nerve function in the Health, Aging and Body Composition Study

BACKGROUND

Chronic kidney disease (CKD) is associated with poor mobility. Peripheral nerve function alterations play a significant role in low mobility. We tested the hypothesis that early CKD is associated with altered sensory, motor and autonomic nerve function.

METHODS

Participants in the Health, Aging and Body Composition cohort who had kidney function measures in Year 3 (1999-2000) and nerve function measurements at Year 4 (2000-01) were analyzed (n = 2290). Sensory (vibration threshold, monofilament insensitivity to light and standard touch), motor [compound motor action potentials (CMAPs), nerve conduction velocities (NCVs)] and autonomic (heart rate response and recovery after a 400-m walk test) nerve function as well as participant characteristics were compared across cystatin C- and creatinine-based estimated glomerular filtration rate categorized as ≤60 (CKD) or >60 mL/min/1.73 m2 (non-CKD). The association between CKD and nerve function was examined with logistic regression adjusted for covariates.

RESULTS

Participants with CKD (n = 476) were older (77 ± 3 versus 75 ± 3 years; P < 0.05) and had a higher prevalence of diabetes (20.6% versus 13.1%; P < 0.001). CKD was associated with higher odds for vibration detection threshold {odds ratio [OR] 1.7 [95% confidence interval (CI) 1.1-2.7]} and light touch insensitivity [OR 1.4 (95% CI 1.1-1.7)]. CMAPs and NCVs were not significantly different between CKD and non-CKD patients. In adjusted analyses, participants with CKD had higher odds of an abnormal heart rate response [OR 1.6 (95% CI 1.1-2.2)] and poor heart rate recovery [OR 1.5 (95% CI 1.1-2.0)].

CONCLUSIONS

CKD is associated with changes in sensory and autonomic nerve function, even after adjustment for demographics and comorbidities, including diabetes. Longitudinal studies in CKD are needed to determine the contribution of nerve impairments to clinically important outcomes.

Genome-wide meta-analysis of variant-by-diuretic interactions as modulators of lipid traits in persons of European and African ancestry

Hypertension (HTN) is a significant risk factor for cardiovascular morbidity and mortality. Metabolic abnormalities, including adverse cholesterol and triglycerides (TG) profiles, are frequent comorbid findings with HTN and contribute to cardiovascular disease. Diuretics, which are used to treat HTN and heart failure, have been associated with worsening of fasting lipid concentrations. Genome-wide meta-analyses with 39,710 European-ancestry (EA) individuals and 9,925 African-ancestry (AA) individuals were performed to identify genetic variants that modify the effect of loop or thiazide diuretic use on blood lipid concentrations. Both longitudinal and cross-sectional data were used to compute cohort-specific interaction results, which were then combined through meta-analysis in each ancestry. These ancestry-specific results were further combined through trans-ancestry meta-analysis. Analysis of EA data identified two genome-wide significant (p < 5×10⁻⁸) loci with single nucleotide variant (SNV)-loop diuretic interaction on TG concentrations (including COL11A1). Analysis of AA data identified one genome-wide significant locus adjacent to BMP2 with SNV-loop diuretic interaction on TG concentrations. Trans-ancestry analysis strengthened evidence of association for SNV-loop diuretic interaction at two loci (KIAA1217 and BAALC). There were few significant SNV-thiazide diuretic interaction associations on TG concentrations and for either diuretic on cholesterol concentrations. Several promising loci were identified that may implicate biologic pathways that contribute to adverse metabolic side effects from diuretic therapy.

Patterns of Physical Activity and Sedentary Behavior for Older Adults with Alzheimer's Disease, Mild Cognitive Impairment, and Cognitively Normal in Hong Kong

BACKGROUND

Alzheimer's disease (AD) is the most common form of dementia, and mild cognitive impairment (MCI) is a transitional phase between healthy cognition and dementia. Physical activity (PA) has protective effects on cognitive decline. However, few studies have examined how PA and sedentary behavior is structured throughout the day in older adults across varied cognitive status in Hong Kong.

OBJECTIVE

This study aimed to compare patterns of PA and sedentary behavior among individuals with AD, MCI, or normal cognition living in Hong Kong.

METHODS

Participants in the MrOs and MsOs Hong Kong cohort study and the Hong Kong AD biomarker study (n = 810) wore a wrist-worn accelerometer for 7 days in free-living environment. Patterns of PA in wake time and in-bed time, and detailed analysis of sedentary bouts were compared between groups using analysis of covariance adjusting for covariates.

RESULTS

Participants with MCI and low MoCA only did not differ from their cognitively normal peers in PA and sedentary behavior. Nevertheless, when comparing to the others, participants with AD exhibited significantly lower average daily counts per minute during the day (p < 0.05), and tended to start their activity later in the morning. AD participants spent a larger proportion of time in sedentary behavior (p < 0.05) and had more sedentary bouts≥30 minutes (p < 0.05).

CONCLUSIONS

The pattern of PA and sedentary behavior was different between individuals with AD and the others. Cognitive status may alter the purpose and type of PA intervention for AD individuals.

Genome-Wide Association Transethnic Meta-Analyses Identifies Novel Associations Regulating Coagulation Factor VIII and von Willebrand Factor Plasma Levels

BACKGROUND

Factor VIII (FVIII) and its carrier protein von Willebrand factor (VWF) are associated with risk of arterial and venous thrombosis and with hemorrhagic disorders. We aimed to identify and functionally test novel genetic associations regulating plasma FVIII and VWF.

METHODS

We meta-analyzed genome-wide association results from 46 354 individuals of European, African, East Asian, and Hispanic ancestry. All studies performed linear regression analysis using an additive genetic model and associated ≈35 million imputed variants with natural log-transformed phenotype levels. In vitro gene silencing in cultured endothelial cells was performed for candidate genes to provide additional evidence on association and function. Two-sample Mendelian randomization analyses were applied to test the causal role of FVIII and VWF plasma levels on the risk of arterial and venous thrombotic events.

RESULTS

We identified 13 novel genome-wide significant ( P≤2.5×10^-8) associations, 7 with FVIII levels ( FCHO2/TMEM171/TNPO1, HLA, SOX17/RP1, LINC00583/NFIB, RAB5C-KAT2A, RPL3/TAB1/SYNGR1, and ARSA) and 11 with VWF levels ( PDHB/PXK/KCTD6, SLC39A8, FCHO2/TMEM171/TNPO1, HLA, GIMAP7/GIMAP4, OR13C5/NIPSNAP, DAB2IP, C2CD4B, RAB5C-KAT2A, TAB1/SYNGR1, and ARSA), beyond 10 previously reported associations with these phenotypes. Functional validation provided further evidence of association for all loci on VWF except ARSA and DAB2IP. Mendelian randomization suggested causal effects of plasma FVIII activity levels on venous thrombosis and coronary artery disease risk and plasma VWF levels on ischemic stroke risk.

CONCLUSIONS

The meta-analysis identified 13 novel genetic loci regulating FVIII and VWF plasma levels, 10 of which we validated functionally. We provide some evidence for a causal role of these proteins in thrombotic events.

Multi-ancestry sleep-by-SNP interaction analysis in 126,926 individuals reveals lipid loci stratified by sleep duration

Both short and long sleep are associated with an adverse lipid profile, likely through different biological pathways. To elucidate the biology of sleep-associated adverse lipid profile, we conduct multi-ancestry genome-wide sleep-SNP interaction analyses on three lipid traits (HDL-c, LDL-c and triglycerides). In the total study sample (discovery + replication) of 126,926 individuals from 5 different ancestry groups, when considering either long or short total sleep time interactions in joint analyses, we identify 49 previously unreported lipid loci, and 10 additional previously unreported lipid loci in a restricted sample of European-ancestry cohorts. In addition, we identify new gene-sleep interactions for known lipid loci such as LPL and PCSK9. The previously unreported lipid loci have a modest explained variance in lipid levels: most notable, gene-short-sleep interactions explain 4.25% of the variance in triglyceride level. Collectively, these findings contribute to our understanding of the biological mechanisms involved in sleep-associated adverse lipid profiles.

Sleep duration is associated with an adverse lipid profile. Here, the authors perform genome-wide gene-by-sleep interaction analysis and find 49 previously unreported lipid loci when considering short or long total sleep time.

A NOVEL METABOLITE COMPOSITE SCORE EXPLAINS THE HIGHER MORTALITY ASSOCIATED WITH FRAILTY AMONG OLDER BLACK MEN

Frailty is more prevalent among black versus white older Americans. We previously sought to better characterize frailty among 287 black men ages 70-81 by identifying 37 plasma metabolites associated with vigor to frailty using the scale of aging vigor in epidemiology (SAVE). Using this information, we developed a metabolite score to determine if it explained the frailty-associated higher mortality. The Human Metabolome Database classified the metabolites as organic acids/derivatives (m=14), lipids/lipid-like molecules (m=12), organoheterocyclic compounds (m=4), benzenoids (m=3), organic nitrogen compounds (m=2), organic oxygen compounds (m=1), and nucleosides/nucleotides/analogues (m=1). Values for each were ranked into tertiles. The metabolite tertile associated with more vigorous SAVE scores was given a score of 0, the metabolite mid-tertile a score of 1, and the metabolite tertile associated with frailer SAVE scores a score of 2. The metabolite composite score was calculated as the sum of the metabolite tertile scores. One standard deviation frailer SAVE was associated with 30% higher mortality (p=0.0002), adjusting for age and study site. The association between frailty and mortality was attenuated by 56% after additionally adjusting for the metabolite score, where organic acids/derivatives and lipids/lipid-like molecules (mostly amino acids, glycerophospholipids, sphingolipids) accounted for most of the attenuation. In this model, one standard deviation higher metabolite score was associated with 46% higher mortality (p&lt;0.0001). The metabolite score also predicted mortality among 48 community-dwelling (96% white) older men (p=0.03). These metabolites provide a deeper characterization of frailty that reproducibly explains a substantial portion of the vulnerability to death in these older men.

The Adiponectin Paradox in the Elderly: Associations With Body Composition, Physical Functioning, and Mortality

Background

To determine if adiponectin levels are associated with weight loss, low muscle mass, and physical functioning among the elderly and to determine independent associations with incident disability and death.

Methods

Included were 3,044 participants from the Health, Aging and Body Composition Study, who had whole-body dual energy absorptiometry performed to evaluate appendicular lean mass index (ALMI, kg/m2) and fat mass index (FMI, kg/m2), computed tomography measures of thigh muscle density, weight histories, estimates of physical functioning, and adiponectin levels at enrollment. Associations between adiponectin levels and body composition, weight loss, and physical functioning were assessed in multivariable linear regression models. Associations between adiponectin and incident disability and mortality were assessed in mediation analyses, adjusting for other factors.

Results

Greater adiponectin at baseline was independently associated with low FMI Z-score, lower waist circumference, low ALMI Z-score, low muscle density, a history of weight loss, and poor physical functioning (all p < .05). Greater adiponectin levels (per SD) were associated with incident disability [HR: 1.14 (1.08, 1.20), p < .001] and greater mortality [HR: 1.17 (1.10, 1.25), p < .001] in models adjusting for demographic factors, adiposity, and comorbid conditions. The association was completely attenuated and no longer significant (all p > 0.05) when adjusting for body composition, muscle density, weight loss, and physical functioning at baseline.

Conclusions

Greater serum adiponectin levels are associated with historical weight loss, low skeletal muscle mass, low muscle density, and poor physical functioning. High adiponectin is associated with a greater risk of incident disability and death, but not independently of these factors.

Associations of autozygosity with a broad range of human phenotypes

In many species, the offspring of related parents suffer reduced reproductive success, a phenomenon known as inbreeding depression. In humans, the importance of this effect has remained unclear, partly because reproduction between close relatives is both rare and frequently associated with confounding social factors. Here, using genomic inbreeding coefficients (FROH) for >1.4 million individuals, we show that FROH is significantly associated (p < 0.0005) with apparently deleterious changes in 32 out of 100 traits analysed. These changes are associated with runs of homozygosity (ROH), but not with common variant homozygosity, suggesting that genetic variants associated with inbreeding depression are predominantly rare. The effect on fertility is striking: FROH equivalent to the offspring of first cousins is associated with a 55% decrease [95% CI 44-66%] in the odds of having children. Finally, the effects of FROH are confirmed within full-sibling pairs, where the variation in FROH is independent of all environmental confounding.

Metabolites Associated With Risk of Developing Mobility Disability in the Health, Aging and Body Composition Study

Background

Metabolic pathways that give rise to functional decline and mobility disability in older adults are incompletely understood.

Methods

To identify metabolic perturbations that may affect functional decline, nontargeted metabolomics was used to measure 350 metabolites in baseline plasma from 313 black men in the Health ABC Study (median age 74 years). Usual gait speed was measured over 20 m. Cross-sectional relationships between gait speed and metabolites were explored with partial correlations adjusted for age, study site, and smoking status. Risk of incident mobility disability (two consecutive reports of severe difficulty walking quarter mile or climb 10 stairs) over 13 years of follow-up was explored with Cox regression models among 307 men who were initially free of mobility disability. Significance was determined at p ≤ .01 and q (false discovery rate) ≤ 0.30.

Results

Two metabolites were correlated with gait speed: salicylurate (r = -.19) and 2-hydroxyglutarate (r = -.18). Metabolites of amino acids and amino acid degradation (indoxy sulfate; hazard ratio [HR] = 1.48, 95% confidence interval [CI] = 1.09-2.03, symmetric dimethylarginine; HR = 3.58, 95% CI = 1.57-8.15, N-carbamoyl beta-alanine; HR = 1.91, 95% CI = 1.16-3.14, quinolinate; HR = 2.56, 95% CI = 1.65-3.96) and metabolites related to kidney function (aforementioned symmetric dimethylarginine and indoxy sulfate as well as creatinine; HR = 5.91, 95% CI = 2.06-16.9, inositol; HR = 2.70, 95% CI = 1.47-4.97) were among the 23 metabolites associated with incident mobility disability.

Conclusions

This study highlights the potential role of amino acid derivatives and products and kidney function early in the development of mobility disability and suggests metabolic profiles could help identify individuals at risk of functional decline.

Metabolite Profiles of Healthy Aging Index Are Associated With Cardiovascular Disease in African Americans: The Health, Aging, and Body Composition Study

Background

Metabolic dysfunction is a hallmark of differential aging, specifically in African Americans. Investigation of systemic metabolic state, multiorgan aging, and long-term cardiovascular outcome in African Americans has not been reported.

Methods

We studied 291 African American males in the Health, Aging, and Body Composition (Health ABC) study to identify circulating metabolites related to the Newman healthy aging index (HAI; a multiparametric score comprised of blood pressure, blood glucose, neurocognitive function, creatinine, and forced vital capacity). We examined the relationship of selected metabolites differential abundant at the extremes of HAI with long-term survival from cardiovascular mortality.

Results

The median age was 73 years. We identified 19 metabolites differentially expressed in blood in 86 study participants at the extremes of HAI (HAI 0-3: N = 30 vs 8-10: N = 56). At a median follow-up of 10 years, 78 participants (27 per cent) died from cardiovascular causes. After adjustment for age, body mass index, presence of prevalent cardiovascular disease, creatinine, and HAI, six of these 19 metabolites were associated with long-term cardiovascular mortality. Although several metabolites had been previously reported in Caucasians (eg, isocitrate), we identified several metabolites with unreported association with cardiac disease. Metabolites associated with HAI and cardiac death in African Americans specified pathways relevant to nitric oxide, oxidative stress, mitochondrial function, urea cycle, and gut microbial metabolism.

Conclusions

Metabolite profiling in African Americans identified known and novel metabolic pathways linked to HAI and cardiovascular death. Further investigation in larger patient cohorts is required to uncover race-based signatures of cardiovascular disease with aging.

Target genes, variants, tissues and transcriptional pathways influencing human serum urate levels

Elevated serum urate levels cause gout and correlate with cardiometabolic diseases via poorly understood mechanisms. We performed a trans-ancestry genome-wide association study of serum urate in 457,690 individuals, identifying 183 loci (147 previously unknown) that improve the prediction of gout in an independent cohort of 334,880 individuals. Serum urate showed significant genetic correlations with many cardiometabolic traits, with genetic causality analyses supporting a substantial role for pleiotropy. Enrichment analysis, fine-mapping of urate-associated loci and colocalization with gene expression in 47 tissues implicated the kidney and liver as the main target organs and prioritized potentially causal genes and variants, including the transcriptional master regulators in the liver and kidney, HNF1A and HNF4A. Experimental validation showed that HNF4A transactivated the promoter of ABCG2, encoding a major urate transporter, in kidney cells, and that HNF4A p.Thr139Ile is a functional variant. Transcriptional coregulation within and across organs may be a general mechanism underlying the observed pleiotropy between urate and cardiometabolic traits.

Cross-Sectional Associations of Neighborhood Perception, Physical Activity, and Sedentary Time in Community-Dwelling, Socioeconomically Diverse Adults

Background: Little is known about the role of perceived neighborhood environment as a determinant of physical activity (PA) and sedentary time (ST) in understanding obesity-related health behaviors. We focus on a biracial, socioeconomically diverse population using objectively measured ST, which is under-represented in the literature.

Methods: We examined the association between self-reported neighborhood perception (Likert-scale questions), PA using the Baecke questionnaire, and both non-sedentary time and ST using accelerometry from wave 4 of the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study (n = 2,167). After applying exclusion criteria, the sample size was n = 1,359 for analyses of self-reported PA and n = 404 for analyses of accelerometry data. Factor analysis identified key neighborhood characteristics to develop a total neighborhood perception score (NPS). Higher NPS indicated less favorable neighborhood perception. Linear regression was used to determine the relationship between NPS, PA, non-sedentary time, and ST.

Results: Complete data were available for n = 1,359 [age 56.6(9.0) years, 59.5% female, 62.2% African American] for whom we identified four neighborhood perception factors: (1) concern about crime, (2) physical environment, (3) location of violent crime, and (4) social environment. Worsening perception of the overall neighborhood [β = −0.13 (SE = 0.03); p = 0.001], the physical environment [−0.11 (0.05); p = 0.03], and the social environment [−0.46 (0.07); p < 0.0001] were associated with decreased PA. Worsening perception of the overall neighborhood [1.14 (0.49); p = 0.02] and neighborhood social environment [3.59 (1.18); p = 0.003] were associated with increased ST over the day. There were no interactions for race, sex, poverty status, or economic index.

Conclusion: Poor overall neighborhood perception, perceived social environment, and perceived neighborhood physical environment are associated with PA and ST in a multi-racial, socioeconomically diverse cohort of urban adults.

Clinical Trial Registration: The HANDLS study is registered at ClinicalTrials.gov as NCT01323322.

Genome-wide association meta-analyses and fine-mapping elucidate pathways influencing albuminuria

Increased levels of the urinary albumin-to-creatinine ratio (UACR) are associated with higher risk of kidney disease progression and cardiovascular events, but underlying mechanisms are incompletely understood. Here, we conduct trans-ethnic (n = 564,257) and European-ancestry specific meta-analyses of genome-wide association studies of UACR, including ancestry- and diabetes-specific analyses, and identify 68 UACR-associated loci. Genetic correlation analyses and risk score associations in an independent electronic medical records database (n = 192,868) reveal connections with proteinuria, hyperlipidemia, gout, and hypertension. Fine-mapping and trans-Omics analyses with gene expression in 47 tissues and plasma protein levels implicate genes potentially operating through differential expression in kidney (including TGFB1, MUC1, PRKCI, and OAF), and allow coupling of UACR associations to altered plasma OAF concentrations. Knockdown of OAF and PRKCI orthologs in Drosophila nephrocytes reduces albumin endocytosis. Silencing fly PRKCI further impairs slit diaphragm formation. These results generate a priority list of genes and pathways for translational research to reduce albuminuria.

Associations of Quadriceps Torque Properties with Muscle Size, Attenuation, and Intramuscular Adipose Tissue in Older Adults

Background

Atrophy and fatty infiltration of muscle with aging are associated with fractures and falls, however, their direct associations with muscle function are not well described. It was hypothesized that participants with lower quadriceps muscle attenuation, area, and greater intramuscular adipose tissue (IMAT) will exhibit slower rates of torque development (RTD) and lower peak knee extension torques.

Methods

Data from 4,842 participants (2,041 men, 2,801 women) from the Age Gene/Environment Susceptibility Reykjavik Study (mean age 76 ± 0.1 years) with complete thigh computed tomography and isometric knee testing. Regression models were adjusted for health, behavior, and comorbidities. Muscle attenuation was further adjusted for muscle area and IMAT; muscle area adjusted for IMAT and attenuation; and IMAT adjusted for muscle area and attenuation. Standardized betas (β) indicate association effect sizes.

Results

In the fully-adjusted models, attenuation (men β = 0.06, 95% CI: 0.01, 0.11; women β = 0.07, 95% CI: 0.03, 0.11) and muscle area (men β = 0.13, 95% CI: 0.07, 0.19; women β = 0.10, 95% CI: 0.06, 0.15) were associated with knee RTD. Attenuation (men β = 0.12, 95% CI: 0.08, 0.16; women β = 0.12, 95% CI: 0.09, 0.16) and muscle area (men β = 0.38, 95% CI: 0.33, 0.43; women β = 0.33, 95% CI: 0.29, 0.37) were associated with peak torque.

Conclusions

These data suggest that muscle attenuation and area are independently associated with RTD and peak torque; and that area and attenuation demonstrate similar contributions to RTD.

Hyperuricemia is associated with intermittent hand joint pain in a cross sectional study of elderly females: The AGES-Reykjavik Study

Background

The debate whether "asymptomatic hyperuricemia" should be treated is still ongoing. The objective of this cross-sectional study was to analyze whether hyperuricema in the elderly is associated with joint pain.

Methods and findings

Participants in the population-based AGES-Reykjavik Study (males 2195, females 2975, mean age 76(6)) answered standardized questions about joint pain. In addition they recorded intermittent hand joint pain by marking a diagram of the hand. In males, no association was found between hyperuricemia and pain. Females however, showed a positive association between hyperuricemia and joint pain at many sites. After adjustment for age, BMI and hand osteoarthritis however, only intermittent hand joint pain (OR 1.30(1.07–1.58), p = 0.008) and intermittent pain in ≥10 hand joints (OR 1.75(1.32–2.31), p<0.001) remained significant. The best model for describing the relationship between serum uric acid levels (SUA) and intermittent hand joint pain in ≥10 joints was non-linear with a cut-off at 372 μmol/L. The attributable surplus number of symptomatic females with SUA ≥372 μmol/L was approximately 2.0% of the study population for those reporting pain in ≥10 hand joints. Next after having severe hand osteoarthritis, SUA ≥372 was an independent predictive factor of intermittent pain in ≥10 hand joints. Intermittent hand joint pain was also an independent risk factor for worse general health description.

Conclusion

Results from this population based study indicate that hyperuricemia in elderly females may be a rather frequent cause of intermittent hand joint pain, often in many joints. The most likely explanation relates to low-grade urate crystal induced inflammation. Our data do not allow for assessment of the severity of symptoms or whether they merit specific treatment, but intermittent hand joint pain was an independent predictor of worse general health. These findings may be an important contribution to the debate on whether hyperuricemia should be treated.

Physical Activity Patterns and Mortality: The Weekend Warrior and Activity Bouts

PURPOSE

This study aimed to examine how accelerometer-assessed physical activity accumulation patterns (e.g., is activity performed daily or only 1 or 2 d·wk or is activity accrued in bouts) may affect the association with mortality.

METHODS

Adults (N = 3438), age 40 yr and older, who wore an accelerometer (ActiGraph 7164), were drawn from the longitudinal follow-up of the National Health and Nutritional Examination Survey (2003-2006), a population-based survey of the United States. Accelerometer-assessed moderate-to-vigorous physical activity (MVPA) was described by activity patterns. Participants engaging in the majority of their activity on only 1 or 2 d·wk· were classified as "weekend warriors." Activity bouts were defined as a period of at least moderate intensity lasting at least 10 min. Bout characteristics included bout frequency and length. Mortality was assessed through National Death Index matching through 2013. Mortality rates were compared among groups with different activity patterns.

RESULTS

Over an average follow-up of 77.4 months, 394 deaths occurred. Compared to participants with <37.5 min of MVPA per week, those with greater amounts of activity had a 60% to 69% mortality rate reduction after adjusting for relevant covariables. Similar risk reductions were found when contrasting weekend warriors with those who were more frequently active. An increase of one MVPA bout per week was associated with a 13% increased mortality rate. Bout duration was not associated with mortality.

CONCLUSION

Physical activity is associated with decreased mortality rate, even among those who are active 1 or 2 d·wk.

A meta-analysis of genome-wide association studies identifies multiple longevity genes

Human longevity is heritable, but genome-wide association (GWA) studies have had limited success. Here, we perform two meta-analyses of GWA studies of a rigorous longevity phenotype definition including 11,262/3484 cases surviving at or beyond the age corresponding to the 90th/99th survival percentile, respectively, and 25,483 controls whose age at death or at last contact was at or below the age corresponding to the 60th survival percentile. Consistent with previous reports, rs429358 (apolipoprotein E (ApoE) ε4) is associated with lower odds of surviving to the 90th and 99th percentile age, while rs7412 (ApoE ε2) shows the opposite. Moreover, rs7676745, located near GPR78, associates with lower odds of surviving to the 90th percentile age. Gene-level association analysis reveals a role for tissue-specific expression of multiple genes in longevity. Finally, genetic correlation of the longevity GWA results with that of several disease-related phenotypes points to a shared genetic architecture between health and longevity.

Oral Health, Disability and Physical Function: Results From Studies of Older People in the United Kingdom and United States of America

OBJECTIVES

Studies examining the associations between oral health and disability have limited oral health measures. We investigated the association of a range of objectively and subjectively assessed oral health markers with disability and physical function in older age.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional analyses were based on the British Regional Heart Study (BRHS) comprising men aged 71 to 92 years (n = 2147) from 24 British towns, and the Health, Aging, and Body Composition (HABC) Study comprising men and women aged 71 to 80 years (n = 3075) from the United States. Assessments included oral health (periodontal disease, tooth count, dry mouth, and self-rated oral health), disability, and physical function (grip strength, gait speed, and chair stand test).

RESULTS

In the BRHS, dry mouth, tooth loss, and cumulative oral health problems (≥3 problems) were associated with mobility limitations and problems with activities of daily living and instrumental activities of daily living; these remained significant after adjustment for confounding variables (for ≥3 dry mouth symptoms, odds ratio (OR) 2.68, 95% confidence interval (CI) 1.94-3.69; OR 1.76, 95% CI 1.15-2.69; OR 2.90, 95% CI 2.01, 4.18, respectively). Similar results were observed in the HABC Study. Dry mouth was associated with the slowest gait speed in the BRHS, and the weakest grip strength in the HABC Study (OR 1.75, 95% CI 1.22, 2.50; OR 2.43, 95% CI 1.47-4.01, respectively).

CONCLUSIONS AND IMPLICATIONS

Markers of poor oral health, particularly dry mouth, poor self-rated oral health, and the presence of more than 1 oral health problem, were associated with disability and poor physical function in older populations. Prospective investigations of these associations and underlying pathways are needed.

A genome-wide association study identifies genetic loci associated with specific lobar brain volumes

Brain lobar volumes are heritable but genetic studies are limited. We performed genome-wide association studies of frontal, occipital, parietal and temporal lobe volumes in 16,016 individuals, and replicated our findings in 8,789 individuals. We identified six genetic loci associated with specific lobar volumes independent of intracranial volume. Two loci, associated with occipital (6q22.32) and temporal lobe volume (12q14.3), were previously reported to associate with intracranial and hippocampal volume, respectively. We identified four loci previously unknown to affect brain volumes: 3q24 for parietal lobe volume, and 1q22, 4p16.3 and 14q23.1 for occipital lobe volume. The associated variants were located in regions enriched for histone modifications (DAAM1 and THBS3), or close to genes causing Mendelian brain-related diseases (ZIC4 and FGFRL1). No genetic overlap between lobar volumes and neurological or psychiatric diseases was observed. Our findings reveal part of the complex genetics underlying brain development and suggest a role for regulatory regions in determining brain volumes.

A multi-ancestry genome-wide study incorporating gene-smoking interactions identifies multiple new loci for pulse pressure and mean arterial pressure

Elevated blood pressure (BP), a leading cause of global morbidity and mortality, is influenced by both genetic and lifestyle factors. Cigarette smoking is one such lifestyle factor. Across five ancestries, we performed a genome-wide gene-smoking interaction study of mean arterial pressure (MAP) and pulse pressure (PP) in 129 913 individuals in stage 1 and follow-up analysis in 480 178 additional individuals in stage 2. We report here 136 loci significantly associated with MAP and/or PP. Of these, 61 were previously published through main-effect analysis of BP traits, 37 were recently reported by us for systolic BP and/or diastolic BP through gene-smoking interaction analysis and 38 were newly identified (P < 5 × 10-8, false discovery rate < 0.05). We also identified nine new signals near known loci. Of the 136 loci, 8 showed significant interaction with smoking status. They include CSMD1 previously reported for insulin resistance and BP in the spontaneously hypertensive rats. Many of the 38 new loci show biologic plausibility for a role in BP regulation. SLC26A7 encodes a chloride/bicarbonate exchanger expressed in the renal outer medullary collecting duct. AVPR1A is widely expressed, including in vascular smooth muscle cells, kidney, myocardium and brain. FHAD1 is a long non-coding RNA overexpressed in heart failure. TMEM51 was associated with contractile function in cardiomyocytes. CASP9 plays a central role in cardiomyocyte apoptosis. Identified only in African ancestry were 30 novel loci. Our findings highlight the value of multi-ancestry investigations, particularly in studies of interaction with lifestyle factors, where genomic and lifestyle differences may contribute to novel findings.

The impact of APOE genotype on survival: Results of 38,537 participants from six population-based cohorts (E2-CHARGE)

BACKGROUND

Apolipoprotein E is a glycoprotein best known as a mediator and regulator of lipid transport and uptake. The APOE-ε4 allele has long been associated with increased risks of Alzheimer's disease and mortality, but the effect of the less prevalent APOE-ε2 allele on diseases in the elderly and survival remains elusive.

METHODS

We aggregated data of 38,537 individuals of European ancestry (mean age 65.5 years; 55.6% women) from six population-based cohort studies (Rotterdam Study, AGES-Reykjavik Study, Cardiovascular Health Study, Health-ABC Study, and the family-based Framingham Heart Study and Long Life Family Study) to determine the association of APOE, and in particular APOE-ε2, with survival in the population.

RESULTS

During a mean follow-up of 11.7 years, 17,021 individuals died. Compared with homozygous APOE-ε3 carriers, APOE-ε2 carriers were at lower risk of death (hazard ratio,95% confidence interval: 0.94,0.90-0.99; P = 1.1*10-2), whereas APOE-ε4 carriers were at increased risk of death (HR 1.17,1.12-1.21; P = 2.8*10-16). APOE was associated with mortality risk in a dose-dependent manner, with risk estimates lowest for homozygous APOE-ε2 (HR 0.89,0.74-1.08), and highest for homozygous APOE-ε4 (HR 1.52,1.37-1.70). After censoring for dementia, effect estimates remained similar for APOE-ε2 (HR 0.95,0.90-1.01), but attenuated for APOE-ε4 (HR 1.07,1.01-1.12). Results were broadly similar across cohorts, and did not differ by age or sex. APOE genotype was associated with baseline lipid fractions (e.g. mean difference(95%CI) in LDL(mg/dL) for ε2 versus ε33: -17.1(-18.1-16.0), and ε4 versus ε33: +5.7(4.8;6.5)), but the association between APOE and mortality was unaltered after adjustment for baseline LDL or cardiovascular disease. Given the European ancestry of the study population, results may not apply to other ethnicities.

CONCLUSION

Compared with APOE-ε3, APOE-ε2 is associated with prolonged survival, whereas mortality risk is increased for APOE-ε4 carriers. Further collaborative efforts are needed to unravel the role of APOE and in particular APOE-ε2 in health and disease.

Exome-Derived Adiponectin-Associated Variants Implicate Obesity and Lipid Biology

Circulating levels of adiponectin, an adipocyte-secreted protein associated with cardiovascular and metabolic risk, are highly heritable. To gain insights into the biology that regulates adiponectin levels, we performed an exome array meta-analysis of 265,780 genetic variants in 67,739 individuals of European, Hispanic, African American, and East Asian ancestry. We identified 20 loci associated with adiponectin, including 11 that had been reported previously (p < 2 × 10^-7). Comparison of exome array variants to regional linkage disequilibrium (LD) patterns and prior genome-wide association study (GWAS) results detected candidate variants (r² > .60) spanning as much as 900 kb. To identify potential genes and mechanisms through which the previously unreported association signals act to affect adiponectin levels, we assessed cross-trait associations, expression quantitative trait loci in subcutaneous adipose, and biological pathways of nearby genes. Eight of the nine loci were also associated (p < 1 × 10^-4) with at least one obesity or lipid trait. Candidate genes include PRKAR2A, PTH1R, and HDAC9, which have been suggested to play roles in adipocyte differentiation or bone marrow adipose tissue. Taken together, these findings provide further insights into the processes that influence circulating adiponectin levels.

Insulin Resistance Exacerbates Genetic Predisposition to Nonalcoholic Fatty Liver Disease in Individuals Without Diabetes

The accumulation of excess fat in the liver (hepatic steatosis) in the absence of heavy alcohol consumption causes nonalcoholic fatty liver disease (NAFLD), which has become a global epidemic. Identifying metabolic risk factors that interact with the genetic risk of NAFLD is important for reducing disease burden. We tested whether serum glucose, insulin, insulin resistance, triglyceride (TG), low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, body mass index (BMI), and waist-to-hip ratio adjusted for BMI interact with genetic variants in or near the patatin-like phospholipase domain containing 3 (PNPLA3) gene, the glucokinase regulatory protein (GCKR) gene, the neurocan/transmembrane 6 superfamily member 2 (NCAN/TM6SF2) gene, and the lysophospholipase-like 1 (LYPLAL1) gene to exacerbate hepatic steatosis, estimated by liver attenuation. We performed association analyses in 10 population-based cohorts separately and then meta-analyzed results in up to 14,751 individuals (11,870 of European ancestry and 2,881 of African ancestry). We found that PNPLA3-rs738409 significantly interacted with insulin, insulin resistance, BMI, glucose, and TG to increase hepatic steatosis in nondiabetic individuals carrying the G allele. Additionally, GCKR-rs780094 significantly interacted with insulin, insulin resistance, and TG. Conditional analyses using the two largest European ancestry cohorts in the study showed that insulin levels accounted for most of the interaction of PNPLA3-rs738409 with BMI, glucose, and TG in nondiabetic individuals. Insulin, PNPLA3-rs738409, and their interaction accounted for at least 8% of the variance in hepatic steatosis in these two cohorts. Conclusion: Insulin resistance, either directly or through the resultant elevated insulin levels, more than other metabolic traits, appears to amplify the PNPLA3-rs738409-G genetic risk for hepatic steatosis. Improving insulin resistance in nondiabetic individuals carrying PNPLA3-rs738409-G may preferentially decrease hepatic steatosis.

Publisher Correction: Protein-altering variants associated with body mass index implicate pathways that control energy intake and expenditure in obesity

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Publisher Correction: Multiancestry genome-wide association study of 520,000 subjects identifies 32 loci associated with stroke and stroke subtypes

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Body fat distribution on computed tomography imaging and prostate cancer risk and mortality in the AGES-Reykjavik study

BACKGROUND

The World Cancer Research Fund classifies as "strong evidence" the link between obesity and the risk of advanced prostate cancer. In light of the different hormonal profiles associated with where adipose is stored, this study investigated the role of objectively measured body fat distribution and the risk of clinically relevant prostate cancer.

METHODS

This was a prospective study of 1832 men in the Age, Gene/Environment Susceptibility-Reykjavik study. From 2002 to 2006, participants underwent baseline computed tomography imaging of fat deposition, bioelectric impedance analysis, and measurement of body mass index (BMI) and waist circumference. Men were followed through linkage with nationwide cancer registries for the incidence of total (n = 172), high-grade (Gleason grade ≥8; n = 43), advanced (≥cT3b/N1/M1 at diagnosis or fatal prostate cancer over follow-up; n = 41), and fatal prostate cancer (n = 31) through 2015. Cox regression was used to evaluate the association between adiposity measures and prostate cancer outcomes.

RESULTS

Among all men, visceral fat (hazard ratio [HR], 1.31 per 1-standard deviation [SD] increase; 95% confidence interval [CI], 1.00-1.72) and thigh subcutaneous fat (HR, 1.37 per 1-SD increase; 95% CI, 1.00-1.88) were associated with risk of advanced and fatal disease, respectively. Among men who were leaner based on BMI, visceral fat was associated with both advanced and fatal disease. BMI and waist circumference were associated with a higher risk of advanced and fatal disease. No adiposity measures were associated with total or high-grade disease.

CONCLUSIONS

Specific fat depots as well as BMI and waist circumference were associated with the risk of aggressive prostate cancer, which may help to elucidate underlying mechanisms and target intervention strategies.