Background The extent to which adult height, a biomarker of the interplay of genetic endowment and early-life experiences, is related to risk of chronic diseases in adulthood is uncertain.
Methods We calculated hazard ratios (HRs) for height, assessed in increments of 6.5 cm, using individual–participant data on 174 374 deaths or major non-fatal vascular outcomes recorded among 1 085 949 people in 121 prospective studies.
Results For people born between 1900 and 1960, mean adult height increased 0.5–1 cm with each successive decade of birth. After adjustment for age, sex, smoking and year of birth, HRs per 6.5 cm greater height were 0.97 (95% confidence interval: 0.96–0.99) for death from any cause, 0.94 (0.93–0.96) for death from vascular causes, 1.04 (1.03–1.06) for death from cancer and 0.92 (0.90–0.94) for death from other causes. Height was negatively associated with death from coronary disease, stroke subtypes, heart failure, stomach and oral cancers, chronic obstructive pulmonary disease, mental disorders, liver disease and external causes. In contrast, height was positively associated with death from ruptured aortic aneurysm, pulmonary embolism, melanoma and cancers of the pancreas, endocrine and nervous systems, ovary, breast, prostate, colorectum, blood and lung. HRs per 6.5 cm greater height ranged from 1.26 (1.12–1.42) for risk of melanoma death to 0.84 (0.80–0.89) for risk of death from chronic obstructive pulmonary disease. HRs were not appreciably altered after further adjustment for adiposity, blood pressure, lipids, inflammation biomarkers, diabetes mellitus, alcohol consumption or socio-economic indicators.
Conclusion Adult height has directionally opposing relationships with risk of death from several different major causes of chronic diseases.
Height; cardiovascular disease; cancer; cause-specific mortality; epidemiological study; meta-analysis
Molluscum contagiosum (MC) is diagnosed by its distinct appearance. Parental diagnosis of MC may reduce anxiety and lead to reductions in healthcare consultations, and may be particularly useful in large-scale epidemiological studies. However, there are currently no published, validated tools allowing parental diagnosis of MC.
To develop and validate a tool for parental diagnosis of MC.
Design and setting
The Molluscum Contagiosum Diagnostic Tool for Parents (MCDTP) was developed and its diagnostic accuracy was compared with GP diagnosis in 12 GP surgeries in South Wales.
Following development, which involved three phases with dermatologists, nurses, GPs, and parents, parents completed the MCDTP (index test) in the practice waiting room, and rated their confidence in their diagnosis. A GP then examined their child for MC (reference test). Test characteristics were calculated for all responders and for those who expressed being confident or very confident in their diagnosis.
A total of 203 parents completed the MCDTP. The MCDTP showed a sensitivity of 91.5% (95% confidence intervals (CI) = 81.3 to 97.2) and a specificity of 88.2% (95% CI = 81.8 to 93.0) in all parents and a sensitivity of 95.8% (95% CI = 85.7 to 99.5) and a specificity of 90.9% (95% CI = 83.9 to 95.6) in parents who were confident or very confident in their diagnosis. The positive predictive value was 76.1% (95% CI = 64.5 to 85.4) and negative predictive value was 96.2% (95% CI = 91.4 to 98.8) for all parents.
The MCDTP performed well compared with GP diagnosis and is suitable for clinical use by parents and in population-based studies.
dermatology; diagnostic tool; epidemiology; general practice; molluscum contagiosum; paediatrics
The value of measuring levels of glycated hemoglobin (HbA1c) for the prediction of first cardiovascular events is uncertain.
To determine whether adding information on HbA1c values to conventional cardiovascular risk factors is associated with improvement in prediction of cardiovascular disease (CVD) risk.
DESIGN, SETTING, AND PARTICIPANTS
Analysis of individual-participant data available from 73 prospective studies involving 294 998 participants without a known history of diabetes mellitus or CVD at the baseline assessment.
MAIN OUTCOMES AND MEASURES
Measures of risk discrimination for CVD outcomes (eg, C-index) and reclassification (eg, net reclassification improvement) of participants across predicted 10-year risk categories of low (<5%), intermediate (5%to <7.5%), and high (≥7.5%) risk.
During a median follow-up of 9.9 (interquartile range, 7.6-13.2) years, 20 840 incident fatal and nonfatal CVD outcomes (13 237 coronary heart disease and 7603 stroke outcomes) were recorded. In analyses adjusted for several conventional cardiovascular risk factors, there was an approximately J-shaped association between HbA1c values and CVD risk. The association between HbA1c values and CVD risk changed only slightly after adjustment for total cholesterol and triglyceride concentrations or estimated glomerular filtration rate, but this association attenuated somewhat after adjustment for concentrations of high-density lipoprotein cholesterol and C-reactive protein. The C-index for a CVD risk prediction model containing conventional cardiovascular risk factors alone was 0.7434 (95% CI, 0.7350 to 0.7517). The addition of information on HbA1c was associated with a C-index change of 0.0018 (0.0003 to 0.0033) and a net reclassification improvement of 0.42 (−0.63 to 1.48) for the categories of predicted 10-year CVD risk. The improvement provided by HbA1c assessment in prediction of CVD risk was equal to or better than estimated improvements for measurement of fasting, random, or postload plasma glucose levels.
CONCLUSIONS AND RELEVANCE
In a study of individuals without known CVD or diabetes, additional assessment of HbA1c values in the context of CVD risk assessment provided little incremental benefit for prediction of CVD risk.
Cathie Sudlow and colleagues describe the UK Biobank, a large population-based prospective study, established to allow investigation of the genetic and non-genetic determinants of the diseases of middle and old age.
Statins increase the risk of new-onset type 2 diabetes mellitus. We aimed to assess whether this increase in risk is a consequence of inhibition of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), the intended drug target.
We used single nucleotide polymorphisms in the HMGCR gene, rs17238484 (for the main analysis) and rs12916 (for a subsidiary analysis) as proxies for HMGCR inhibition by statins. We examined associations of these variants with plasma lipid, glucose, and insulin concentrations; bodyweight; waist circumference; and prevalent and incident type 2 diabetes. Study-specific effect estimates per copy of each LDL-lowering allele were pooled by meta-analysis. These findings were compared with a meta-analysis of new-onset type 2 diabetes and bodyweight change data from randomised trials of statin drugs. The effects of statins in each randomised trial were assessed using meta-analysis.
Data were available for up to 223 463 individuals from 43 genetic studies. Each additional rs17238484-G allele was associated with a mean 0·06 mmol/L (95% CI 0·05–0·07) lower LDL cholesterol and higher body weight (0·30 kg, 0·18–0·43), waist circumference (0·32 cm, 0·16–0·47), plasma insulin concentration (1·62%, 0·53–2·72), and plasma glucose concentration (0·23%, 0·02–0·44). The rs12916 SNP had similar effects on LDL cholesterol, bodyweight, and waist circumference. The rs17238484-G allele seemed to be associated with higher risk of type 2 diabetes (odds ratio [OR] per allele 1·02, 95% CI 1·00–1·05); the rs12916-T allele association was consistent (1·06, 1·03–1·09). In 129 170 individuals in randomised trials, statins lowered LDL cholesterol by 0·92 mmol/L (95% CI 0·18–1·67) at 1-year of follow-up, increased bodyweight by 0·24 kg (95% CI 0·10–0·38 in all trials; 0·33 kg, 95% CI 0·24–0·42 in placebo or standard care controlled trials and −0·15 kg, 95% CI −0·39 to 0·08 in intensive-dose vs moderate-dose trials) at a mean of 4·2 years (range 1·9–6·7) of follow-up, and increased the odds of new-onset type 2 diabetes (OR 1·12, 95% CI 1·06–1·18 in all trials; 1·11, 95% CI 1·03–1·20 in placebo or standard care controlled trials and 1·12, 95% CI 1·04–1·22 in intensive-dose vs moderate dose trials).
The increased risk of type 2 diabetes noted with statins is at least partially explained by HMGCR inhibition.
The funding sources are cited at the end of the paper.
Background. Haptoglobin acts as an antioxidant by limiting peroxidative tissue damage by free hemoglobin. The haptoglobin gene allele Hp2 comprises a 1.7 kb partial duplication. Relative to allele Hp1, Hp2 carriers form protein multimers, suboptimal for hemoglobin scavenging. Objective. To examine the association of haptoglobin genotype with a range of phenotypes, with emphasis on vitamin C and hemoglobin levels. Methods. We applied a quantitative PCR assay for the duplication junction to two population cohorts including 2747 British women and 1198 British men. We examined the association of haptoglobin duplicon copy number with hemoglobin and vitamin C and used the copy number to complete a phenome scan. Results. Hemoglobin concentrations were greater in those with Hp2,2 genotype, in women only (Hp1,1 13.45 g/dL, Hp1,2 13.49 g/dL, Hp2,2 13.61 g/dL; P = 0.002), though statistically there was no evidence of a difference between the sexes (z value = 1.2, P = 0.24). Haptoglobin genotype was not associated with vitamin C or any other phenotype in either cohort. Conclusions. Our results do not support association of haptoglobin genotype with vitamin C or with other phenotypes measured in two population cohorts. The apparent association between haptoglobin genotype and hemoglobin in the women's cohort merits further investigation.
Objective measures of physical capability are being used in a growing number of studies as biomarkers of healthy ageing. However, very little research has been done to assess the impact of physical capability on subsequent positive mental wellbeing, the maintenance of which is widely considered to be an essential component of healthy ageing. We aimed to test the associations of grip strength and walking, timed get up and go and chair rise speeds (assessed at ages 53 to 82 years) with positive mental wellbeing assessed using the Warwick Edinburgh Mental Wellbeing Scale (WEMWBS) five to ten years later. Data were drawn from five British cohorts participating in the HALCyon research collaboration. Data from each study were analysed separately and then combined using random-effects meta-analyses. Higher levels of physical capability were consistently associated with higher subsequent levels of wellbeing; for example, a 1SD increase in grip strength was associated with an age and sex-adjusted mean difference in WEMWBS score of 0.81 (0.25, 1.37), equivalent to 10% of a standard deviation (3 studies, N=3,096). When adjusted for body size, health status, living alone, socioeconomic position and neuroticism the associations remained albeit attenuated. The finding of these consistent modest associations across five studies, spanning early and later old age, highlights the importance of maintaining physical capability in later life and provides additional justification for using objective measures of physical capability as markers of healthy ageing.
physical capability; positive mental wellbeing; grip strength; walking speed; chair rise time
Alzheimer's disease is a common debilitating dementia with known heritability, for which 20 late onset susceptibility loci have been identified, but more remain to be discovered. This study sought to identify new susceptibility genes, using an alternative gene-wide analytical approach which tests for patterns of association within genes, in the powerful genome-wide association dataset of the International Genomics of Alzheimer's Project Consortium, comprising over 7 m genotypes from 25,580 Alzheimer's cases and 48,466 controls.
In addition to earlier reported genes, we detected genome-wide significant loci on chromosomes 8 (TP53INP1, p = 1.4×10−6) and 14 (IGHV1-67 p = 7.9×10−8) which indexed novel susceptibility loci.
The additional genes identified in this study, have an array of functions previously implicated in Alzheimer's disease, including aspects of energy metabolism, protein degradation and the immune system and add further weight to these pathways as potential therapeutic targets in Alzheimer's disease.
Eleven susceptibility loci for late-onset Alzheimer’s disease (LOAD) were identified by previous studies; however, a large portion of the genetic risk for this disease remains unexplained. We conducted a large, two-stage meta-analysis of genome-wide association studies (GWAS) in individuals of European ancestry. In stage 1, we used genotyped and imputed data (7,055,881 SNPs) to perform meta-analysis on 4 previously published GWAS data sets consisting of 17,008 Alzheimer’s disease cases and 37,154 controls. In stage 2,11,632 SNPs were genotyped and tested for association in an independent set of 8,572 Alzheimer’s disease cases and 11,312 controls. In addition to the APOE locus (encoding apolipoprotein E), 19 loci reached genome-wide significance (P < 5 × 10−8) in the combined stage 1 and stage 2 analysis, of which 11 are newly associated with Alzheimer’s disease.
Insulin-like growth factors are peptide hormones that have an endocrine role in the development, growth and repair of human tissues including the respiratory tract. To date, only one population study exists which found positive cross-sectional associations with IGF-I and higher lung volumes. We hypothesised that higher IGF-I, IGF-II, IGFBP-3 and IGF molar ratio would be associated with better cross-sectional and longitudinal lung function. We examined cross-sectional (n=843) and prospective associations (n=717) between IGF-I, IGF-II, IGFBP-3 and IGF molar ratio with lung function in the Caerphilly Prospective Study (CaPS) from blood samples obtained around 1986, with spirometry (forced expiratory volume in one second (FEV1) and forced vital capacity (FVC)) performed in the same year and around 2003. Higher IGF molar ratio was associated with improved FEV1/FEV ratio cross-sectionally in both simple (0.007, 95% CI 0.001-0.013, P=0.02) and fully adjusted (0.001, 95% CI 0.001-0.012, P=0.03) models. With the exception of IGFBP-3 and FEV1/FVC in the simple model (0.009, 95% CI 0.001-0.018, P=0.04) all prospective associations between IGF and spirometric measures were consistent with chance. In this study of men, higher IGF molar ratio was associated with improved cross-sectional lung function, although these findings were not replicated prospectively. Further work is required with repeat IGF sampling during follow up to see if IGF levels play any role in predicting future lung function through the life course.
Insulin-like growth factors; cohort study; spirometry; lung function
Previous studies on the association between adiposity and mood disorder have produced contradictory results, and few have used measurements other than body mass index (BMI). We examined the association between probable major depression and several measurements of adiposity: BMI, waist circumference (WC), waist-hip-ratio (WHR), and body fat percentage (BF%).
We conducted a cross-sectional study using baseline data on the sub-group of UK Biobank participants who were assessed for mood disorder. Multivariate logistic regression models were used, adjusting for potential confounders including: demographic and life-style factors, comorbidity and psychotropic medication.
Of the 140,564 eligible participants, evidence of probable major depression was reported by 30,145 (21.5%). The fully adjusted odds ratios (OR) for obese participants were 1.16 (95% confidence interval (CI) 1.12, 1.20) using BMI, 1.15 (95% CI 1.11, 1.19) using WC, 1.09 (95% CI 1.05, 1.13) using WHR and 1.18 (95% CI 1.12, 1.25) using BF% (all p < 0.001). There was a significant interaction between adiposity and gender (p = 0.001). Overweight women were at increased risk of depression with a dose response relationship across the overweight (25.0-29.9 kg/m2), obese I (30.0-34.9 kg/m2), II (35.0-39.9 kg/m2) and III (≥40.0 kg/m2) categories; fully adjusted ORs 1.14, 1.20, 1.29 and 1.48, respectively (all p < 0.001). In contrast, only obese III men had significantly increased risk of depression (OR 1.29, 95% CI 1.08, 1.54, p = 0.006).
Adiposity was associated with probable major depression, irrespective of the measurement used. The association was stronger in women than men. Physicians managing overweight and obese women should be alert to this increased risk.
Adiposity; Obesity; Depression; Mental health; Mood disorder; UK Biobank
The built environment in which older people live plays an important role in promoting or inhibiting physical activity. Most work on this complex relationship between physical activity and the environment has excluded people with reduced physical function or ignored the difference between groups with different levels of physical function. This study aims to explore the role of neighbourhood green space in determining levels of participation in physical activity among elderly men with different levels of lower extremity physical function.
Using data collected from the Caerphilly Prospective Study (CaPS) and green space data collected from high resolution Landmap true colour aerial photography, we first investigated the effect of the quantity of neighbourhood green space and the variation in neighbourhood vegetation on participation in physical activity for 1,010 men aged 66 and over in Caerphilly county borough, Wales, UK. Second, we explored whether neighbourhood green space affects groups with different levels of lower extremity physical function in different ways.
Increasing percentage of green space within a 400 meters radius buffer around the home was significantly associated with more participation in physical activity after adjusting for lower extremity physical function, psychological distress, general health, car ownership, age group, marital status, social class, education level and other environmental factors (OR = 1.21, 95% CI 1.05, 1.41). A statistically significant interaction between the variation in neighbourhood vegetation and lower extremity physical function was observed (OR = 1.92, 95% CI 1.12, 3.28).
Elderly men living in neighbourhoods with more green space have higher levels of participation in regular physical activity. The association between variation in neighbourhood vegetation and regular physical activity varied according to lower extremity physical function. Subjects reporting poor lower extremity physical function living in neighbourhoods with more homogeneous vegetation (i.e. low variation) were more likely to participate in regular physical activity than those living in neighbourhoods with less homogeneous vegetation (i.e. high variation). Good lower extremity physical function reduced the adverse effect of high variation vegetation on participation in regular physical activity. This provides a basis for the future development of novel interventions that aim to increase levels of physical activity in later life, and has implications for planning policy to design, preserve, facilitate and encourage the use of green space near home.
Green space; Lower extremity physical function; Physical activity; Elderly men
Individual participant time-to-event data from multiple prospective epidemiologic studies enable detailed investigation into the predictive ability of risk models. Here we address the challenges in appropriately combining such information across studies. Methods are exemplified by analyses of log C-reactive protein and conventional risk factors for coronary heart disease in the Emerging Risk Factors Collaboration, a collation of individual data from multiple prospective studies with an average follow-up duration of 9.8 years (dates varied). We derive risk prediction models using Cox proportional hazards regression analysis stratified by study and obtain estimates of risk discrimination, Harrell's concordance index, and Royston's discrimination measure within each study; we then combine the estimates across studies using a weighted meta-analysis. Various weighting approaches are compared and lead us to recommend using the number of events in each study. We also discuss the calculation of measures of reclassification for multiple studies. We further show that comparison of differences in predictive ability across subgroups should be based only on within-study information and that combining measures of risk discrimination from case-control studies and prospective studies is problematic. The concordance index and discrimination measure gave qualitatively similar results throughout. While the concordance index was very heterogeneous between studies, principally because of differing age ranges, the increments in the concordance index from adding log C-reactive protein to conventional risk factors were more homogeneous.
C index; coronary heart disease; D measure; individual participant data; inverse variance; meta-analysis; risk prediction; weighting
Healthy lifestyles based on non-smoking, an acceptable BMI, a high fruit and vegetable intake, regular physical activity, and low/moderate alcohol intake, are associated with reductions in the incidence of certain chronic diseases, but to date there is limited evidence on cognitive function and dementia.
In 1979 healthy behaviours were recorded on 2,235 men aged 45–59 years in Caerphilly, UK. During the following 30 years incident diabetes, vascular disease, cancer and death were recorded, and in 2004 cognitive state was determined.
Men who followed four or five of the behaviours had an odds ratio (OR) and confidence intervals (CI) for diabetes, corrected for age and social class, of 0.50 (95% CI: 0.19, 1.31; P for trend with increasing numbers of healthy behaviours <0.0005). For vascular disease the OR was 0.50 (95% CI: 0.30, 0.84; P for trend <0.0005), and there was a delay in vascular disease events of up to 12 years. Cancer incidence was not significantly related to lifestyle although there was a reduction associated with non-smoking (OR: 0.65; 95% CI: 0.54, 0.79). All-cause mortality was reduced in men following four or five behaviours (OR 0.40; 95% CI: 0.24, 0.67; P for trend <0.005).
After further adjustment for NART, the OR for men following four or five healthy behaviours was 0.36 (95% CI: 0.12, 1.09; P for trend <0.001) for cognitive impairment, and 0.36 (95% CI: 0.07, 1.99; P for trend <0.02) for dementia.
The adoption of a healthy lifestyle by men was low and appears not to have changed during the subsequent 30 years, with under 1% of men following all five of the behaviours and 5% reporting four or more in 1979 and in 2009.
A healthy lifestyle is associated with increased disease-free survival and reduced cognitive impairment but the uptake remains low.
UK Biobank is a landmark cohort of over 500,000 participants which will be used to investigate genetic and non-genetic risk factors for a wide range of adverse health outcomes. This is the first study to systematically assess the prevalence and validity of proposed criteria for probable mood disorders within the cohort (major depression and bipolar disorder).
This was a descriptive epidemiological study of 172,751 individuals assessed for a lifetime history of mood disorder in relation to a range of demographic, social, lifestyle, personality and health-related factors. The main outcomes were prevalence of a probable lifetime (single) episode of major depression, probable recurrent major depressive disorder (moderate), probable recurrent major depressive disorder (severe), probable bipolar disorder and no history of mood disorder (comparison group). Outcomes were compared on age, gender, ethnicity, socioeconomic status, educational attainment, functioning, self-reported health status, current depressive symptoms, neuroticism score, smoking status and alcohol use.
Prevalence rates for probable single lifetime episode of major depression (6.4%), probable recurrent major depression (moderate) (12.2%), probable recurrent major depression (severe) (7.2%) and probable bipolar disorder (1.3%) were comparable to those found in other population studies. The proposed diagnostic criteria have promising validity, with a gradient in evidence from no mood disorder through major depression and probable bipolar disorder in terms of gender distribution, socioeconomic status, self-reported health rating, current depressive symptoms and smoking.
The validity of our proposed criteria for probable major depression and probable bipolar disorder within this cohort are supported by these cross-sectional analyses. Our findings are likely to prove useful as a framework for a wide range of future genetic and non-genetic studies.
Background: studies have shown that milk and dairy consumption in adulthood have beneficial effects on health.
Methods: we examined the impact of childhood and adult diet on physical performance at age 63–86 years. The Boyd Orr cohort (n = 405) is a 65-year prospective study of children who took part in a 1930's survey; the Caerphilly Prospective Study (CaPS; n = 1,195) provides data from mid-life to old age. We hypothesised that higher intakes of childhood and adult milk, calcium, protein, fat and energy would be associated with a better performance.
Results: in fully adjusted models, a standard deviation (SD) increase in natural log-transformed childhood milk intake was associated with 5% faster walking times from the get-up and go test in Boyd Orr (95% CI: 1 to 9) and 25% lower odds of poor balance (OR: 0.75; 0.55 to 1.02). Childhood calcium intake was positively associated with walking times (4% faster per SD; 0 to 8) and a higher protein intake was associated with lower odds of poor balance (OR: 0.71; 0.54 to 0.92). In adulthood, protein intake was positively associated with walking times (2% faster per SD; 1 to 3; Boyd Orr and CaPS pooled data).
Conclusion: this is the first study to show positive associations of childhood milk intake with physical performance in old age.
diet; physical performance; walking speed; standing balance; older people
Few studies have examined the impact of the built environment configuration upon mental health. The study examines the impact of objectively assessed land use and street network configuration upon psychological distress and whether this association is moderated by the natural environment and area-level deprivation.
In a community sample of 687 older men from the Caerphilly Prospective Study, built environment morphological metrics (morphometrics) were related to differences in psychological distress as measured by the General Health Questionnaire. Cross-sectional data were taken from the most recent (5th) phase. A multi-level analysis with individuals nested within census-defined neighbourhoods was conducted. Environmental measures comprised GIS-constructed land use and street network metrics, slope variability and a satellite derived measure of greenness.
Reduced psychological distress was associated with residing in a terraced dwelling (OR = 0.48, p = 0.03), higher degrees of land-use mix (OR = 0.42, p = 0.03 for the high tertile) and having higher local-level street-network accessibility (‘movement potential’) (OR = 0.54, p = 0.03). Hillier topography with higher slope variability was associated with increased risks of psychological distress (OR = 1.38, p = 0.05).
The findings support our hypothesis that built environment configuration is independently associated with psychological distress. The study underscores the need for effective intervention in the planning and design of residential built environment to achieve the goal of health-sustaining communities.
Psychological distress; GHQ; Older adults; Built environment configuration; Space syntax; Random effects; Runmlwin
Telomeres are involved in cellular ageing and shorten with increasing age. If telomere length is a valuable biomarker of ageing, then telomere shortening should be associated with worse physical performance, an ageing trait, but evidence for such an association is lacking. The purpose of this study was to examine whether change in telomere length is associated with physical performance.
Using data from four UK adult cohorts (ages 53–80 years at baseline), we undertook cross-sectional and longitudinal analyses. We analysed each study separately and then used meta-analytic methods to pool the results. Physical performance was measured using walking and chair rise speed, standing balance time and grip strength. Telomere length was measured by quantitative real-time polymerase chain reaction (PCR) in whole blood at baseline and follow-up (time 1, time 2).
Total sample sizes in meta-analyses ranged from 1,217 to 3,707. There was little evidence that telomere length was associated with walking speed, balance or grip strength, though weak associations were seen with chair rise speed and grip strength at baseline (p = 0.02 and 0.01 respectively). Faster chair rise speed at follow-up, was associated with a smaller decline in telomere length between time 1 and time 2 (standardised coefficient per SD increase 0.061, 95% CI 0.006, 0.115, p = 0.03) but this was consistent with chance (p = 0.08) after further adjustment.
Whereas shortening of leukocyte telomeres might be an important measure of cellular ageing, there is little evidence that it is a strong biomarker for physical performance.
Objective measures of physical capability are being used in a growing number of studies as biomarkers of healthy ageing. However, very little research has been done to assess the impact of physical capability on subsequent positive mental wellbeing, the maintenance of which is widely considered to be an essential component of healthy ageing. We aimed to test the associations of grip strength and walking, timed get up and go and chair rise speeds (assessed at ages 53 to 82 years) with positive mental wellbeing assessed using the Warwick–Edinburgh Mental Wellbeing Scale (WEMWBS) 5 to 10 years later. Data were drawn from five British cohorts participating in the Healthy Ageing across the Life Course research collaboration. Data from each study were analysed separately and then combined using random-effects meta-analyses. Higher levels of physical capability were consistently associated with higher subsequent levels of wellbeing; for example, a 1SD increase in grip strength was associated with an age and sex-adjusted mean difference in WEMWBS score of 0.81 (0.25, 1.37), equivalent to 10 % of a standard deviation (three studies, N = 3,096). When adjusted for body size, health status, living alone, socioeconomic position and neuroticism the associations remained albeit attenuated. The finding of these consistent modest associations across five studies, spanning early and later old age, highlights the importance of maintaining physical capability in later life and provides additional justification for using objective measures of physical capability as markers of healthy ageing.
Electronic supplementary material
The online version of this article (doi:10.1007/s11357-013-9553-8) contains supplementary material, which is available to authorized users.
Physical capability; Positive mental wellbeing; Grip strength; Walking speed; Chair rise time
To investigate the associations of body mass index (BMI) and grip strength with objective measures of physical performance (chair rise time, walking speed and balance) including an assessment of sex differences and non-linearity.
Cross-sectional data from eight UK cohort studies (total N = 16 444) participating in the Healthy Ageing across the Life Course (HALCyon) research programme, ranging in age from 50 to 90+ years at the time of physical capability assessment, were used. Regression models were fitted within each study and meta-analysis methods used to pool regression coefficients across studies and to assess the extent of heterogeneity between studies.
Higher BMI was associated with poorer performance on chair rise (N = 10 773), walking speed (N = 9 761) and standing balance (N = 13 921) tests. Higher BMI was associated with stronger grip strength in men only. Stronger grip strength was associated with better performance on all tests with a tendency for the associations to be stronger in women than men; for example, walking speed was higher by 0.43 cm/s (0.14, 0.71) more per kg in women than men. Both BMI and grip strength remained independently related with performance after mutual adjustment, but there was no evidence of effect modification. Both BMI and grip strength exhibited non-linear relations with performance; those in the lowest fifth of grip strength and highest fifth of BMI having particularly poor performance. Findings were similar when waist circumference was examined in place of BMI.
Older men and women with weak muscle strength and high BMI have considerably poorer performance than others and associations were observed even in the youngest cohort (age 53). Although causality cannot be inferred from observational cross-sectional studies, our findings suggest the likely benefit of early assessment and interventions to reduce fat mass and improve muscle strength in the prevention of future functional limitations.
Gene-environment interaction studies offer the prospect of robust causal inference through both gene identification and instrumental variable approaches. As such they are a major and much needed development. However, conducting these studies using traditional methods, which require direct participant contact, is resource intensive. The ability to conduct gene-environment interaction studies remotely would reduce costs and increase capacity.
To develop a platform for the remote conduct of gene-environment interaction studies.
A random sample of 15,000 men and women aged 50+ years and living in Cardiff, South Wales, of whom 6,012 were estimated to have internet connectivity, were mailed inviting them to visit a web-site to join a study of successful ageing. Online consent was obtained for questionnaire completion, cognitive testing, re-contact, record linkage and genotyping. Cognitive testing was conducted using the Cardiff Cognitive Battery. Bio-sampling was randomised to blood spot, buccal cell or no request.
A heterogeneous sample of 663 (4.5% of mailed sample and 11% of internet connected sample) men and women (47% female) aged 50–87 years (median = 61 yrs) from diverse backgrounds (representing the full range of deprivation scores) was recruited. Bio-samples were donated by 70% of those agreeing to do so. Self report questionnaires and cognitive tests showed comparable distributions to those collected using face-to-face methods. Record linkage was achieved for 99.9% of participants.
This study has demonstrated that remote methods are suitable for the conduct of gene-environment interaction studies. Up-scaling these methods provides the opportunity to increase capacity for large-scale gene-environment interaction studies.
The association between functioning of the hypothalamic pituitary adrenal (HPA) axis and physical performance at older ages remains poorly understood. We carried out meta-analyses to test the hypothesis that dysregulation of the HPA axis, as indexed by patterns of diurnal cortisol release, is associated with worse physical performance. Data from six adult cohorts (ages 50–92 years) were included in a two stage meta-analysis of individual participant data. We analysed each study separately using linear and logistic regression models and then used meta-analytic methods to pool the results. Physical performance outcome measures were walking speed, balance time, chair rise time and grip strength. Exposure measures were morning (serum and salivary) and evening (salivary) cortisol. Total sample sizes in meta-analyses ranged from n = 2146 for associations between morning Cortisol Awakening Response and balance to n = 8448 for associations between morning cortisol and walking speed. A larger diurnal drop was associated with faster walking speed (standardised coefficient per SD increase 0.052, 95% confidence interval (CI) 0.029, 0.076, p < 0.001; age and gender adjusted) and a quicker chair rise time (standardised coefficient per SD increase −0.075, 95% CI −0.116, −0.034, p < 0.001; age and gender adjusted). There was little evidence of associations with balance or grip strength. Greater diurnal decline of the HPA axis is associated with better physical performance in later life. This may reflect a causal effect of the HPA axis on performance or that other ageing-related factors are associated with both reduced HPA reactivity and performance.
HPA axis; Physical capability; Healthy ageing
Socioeconomic influences over a lifetime impact on health and may contribute to poor physical functioning in old age.
We examined the impact of both childhood and adulthood socioeconomic factors on locomotor function at 63-86 years (measured with the get up and go timed walk and flamingo balance test), in the UK-based Boyd Orr (n=405) and Caerphilly (n=1,196) prospective cohorts.
There was a marked reduction in walking speed and balance time with increasing age. Each year of age was associated with a 1.7% slower walk time and a 14% increased odds of poor balance. Participants who moved from a low socioeconomic position in childhood to a high socioeconomic position in adulthood had walking times 3% slower (95% CI: -2%, 8%) than people with high socioeconomic position in both periods. Participants who moved from a high socioeconomic position in childhood to a low adulthood socioeconomic position had walking times 5% slower (95% CI: -2%, 12%). Participants with a low socioeconomic position in both periods had walking times 10% slower (95% CI: 5%, 16%; P for trend <0.001).
In Boyd Orr, low socioeconomic position in childhood was associated with poor balance in old age (OR per worsening category = 1.26; 95% CI 1.01, 1.57; P=0.043), as was socioeconomic position in adulthood (OR = 1.71; 95% CI 1.20, 2.45; P=0.003). Similar associations were not observed in Caerphilly.
Accumulating socioeconomic disadvantage from childhood to adulthood is associated with slower walking time in old age, with mixed results for balance ability.
Aged; Gait; Physical performance; Social Class; Socioeconomic Factors