The Danish 1905 cohort: a genetic-epidemiological nationwide survey

Cognitively high-performing oldest old individuals are physically active and have strong motor skills-A study of the Danish 1905 and 1915 birth cohorts

Preserving cognitive function with age or super-aging greatly contributes to successful aging. Super-aging nonagenarians born in Denmark in either year 1905 or 1915 were classified as Cognitively High-Performing Oldest Old individuals with a five item cognitive composite score, equivalent to or better than mean middle-aged subjects. Cognitively high-performers were more physically active and had a better physical performance on e.g., Activity of Daily Living (p-value < 0.01), gait speed (p-value < 0.01) and grip strength (p-value < 0.05) compared with age-matched peers. Cognitive high-performing was also linked to lower depression symptomatology. When comparing super-agers with semi super-agers classified by Mini Mental State Examination > 27, super-agers were still more physically active and had a better physical performance (p-value < 0.05). Results suggests that physical activity is a lifestyle factor strongly associated with both semi and full cognitive super-aging.

Understanding Health Deterioration and the Dynamic Relationship between Physical Ability and Cognition among a Cohort of Danish Nonagenarians

This study aims to determine how demographics, socioeconomic characteristics, and lifestyle affect physical and cognitive health transitions among nonagenarians, whether these transitions follow the same patterns, and how each dimension affects the transitions of the other. We applied a multistate model for panel data to 2262 individuals over a 2-year follow-up period from the 1905 Danish Cohort survey. Within two years from baseline, the transition probability from good to bad physical health-ability to stand up from a chair-was higher than dying directly (29% vs. 25%), while this was not observed for cognition (24% vs. 27%) evaluated with Mini-Mental State Examination-a score lower than 24 indicates poor cognitive health. Probability of dying either from bad physical or cognitive health condition was 50%. Health transitions were associated with sex, education, living alone, body mass index, and physical activity. Physical and cognitive indicators were associated with deterioration of cognitive and physical status, respectively, and with survivorship from a bad health condition. We conclude that physical and cognitive health deteriorated differently among nonagenarians, even if they were related to similar sociodemographic and lifestyle characteristics and resulted dynamically related with each other.

Is Who you Ask Important? Concordance Between Survey and Registry Data on Medication Use Among Self- and Proxy-Respondents in the Longitudinal Study of Aging Danish Twins and the Danish 1905-Cohort Study

Background

This study investigates the accuracy of the reporting of medication use by proxy- and self-respondents, and it compares the prognostic value of the number of medications from survey and registry data for predicting mortality across self- and proxy-respondents.

Methods

The study is based on the linkage of the Longitudinal Study of Aging Danish Twins and the Danish 1905–Cohort Study with the Danish National Prescription Registry. We investigated the concordance between survey and registry data, and the prognostic value of medication use when assessed using survey and registry data, to predict mortality for self- and proxy-respondents at intake surveys.

Results

Among self-respondents, the agreement was moderate (κ = 0.52–0.58) for most therapeutic groups, whereas among proxy-respondents, the agreement was low to moderate (κ = 0.36–0.60). The magnitude of the relative differences was, generally, greater among proxies than among self-respondents. Each additional increase in the total number of medications was associated with 7%–8% mortality increase among self- and 4%–6% mortality increase among proxy-respondents in both the survey and registry data. The predictive value of the total number of medications estimated from either data source was lower among proxies (c-statistic = 0.56–0.58) than among self-respondents (c-statistic = 0.74).

Conclusions

The concordance between survey and registry data regarding medication use and the predictive value of the number of medications for mortality were lower among proxy- than among self-respondents.

Independent Functioning in Nonagenarians Living in a Rural Italian Community: The Mugello Study

Nonagenarians are a fast-growing population deserving specific research. We explored the prevalence and characteristics of functionally independent nonagenarians from a rural community-dwelling Italian population. Data were collected in the Mugello Study; 475 persons aged ≥90 years (median age, 92) underwent a home-based clinical and functional assessment, including psychosocial, clinical, functional, and lifestyle history and status and physical and instrumental examinations. Sixty-eight (15%) persons reported no need for help in basic and instrumental daily living activities. Among variables significantly associated with independent functionality after age- and gender-adjusted cross-sectional analysis, lower body mass index (BMI; p = .034) and depressive symptoms (p = .028), higher current physical activity (p < .001), better cognitive status (p = .033), and lower medication intake (p = .048) were associated with reporting no disability in the logistic regression analysis. Disability was mainly associated with current lifestyle-related potentially modifiable factors. Thus, lifestyle-oriented multidimensional interventions, should be developed and evaluated for their potential effects on functionality, even in the oldest old.

Integration of heterogeneous functional genomics data in gerontology research to find genes and pathway underlying aging across species

Understanding the biological mechanisms behind aging, lifespan and healthspan is becoming increasingly important as the proportion of the world's population over the age of 65 grows, along with the cost and complexity of their care. BigData oriented approaches and analysis methods enable current and future bio-gerontologists to synthesize, distill and interpret vast, heterogeneous data from functional genomics studies of aging. GeneWeaver is an analysis system for integration of data that allows investigators to store, search, and analyze immense amounts of data including user-submitted experimental data, data from primary publications, and data in other databases. Aging related genome-wide gene sets from primary publications were curated into this system in concert with data from other model-organism and aging-specific databases, and applied to several questions in genrontology using. For example, we identified Cd63 as a frequently represented gene among aging-related genome-wide results. To evaluate the role of Cd63 in aging, we performed RNAi knockdown of the C. elegans ortholog, tsp-7, demonstrating that this manipulation is capable of extending lifespan. The tools in GeneWeaver enable aging researchers to make new discoveries into the associations between the genes, normal biological processes, and diseases that affect aging, healthspan, and lifespan.

Trajectories of Nonagenarian Health: Sex, Age, and Period Effects

The US population aged 90 years or more is growing rapidly, and there are limited data on their health. The Cardiovascular Health Study is a prospective study of black and white adults aged ≥65 years recruited in 2 waves (1989-1990 and 1992-1993) from Medicare eligibility lists in Forsyth County, North Carolina; Sacramento County, California; Washington County, Maryland; and Pittsburgh, Pennsylvania. We created a synthetic cohort of the 1,889 participants who had reached age 90 years at baseline or during follow-up through July 16, 2015. Participants entered the cohort at 90 years of age, and we evaluated their changes in health after age 90 years (median duration of follow-up, 3 years (interquartile range, 1.3-5)). Measures of health included cardiovascular events, cognitive function, depressive symptoms, prescription medications, self-rated health, and functional status. The mortality rate was high: 19.0 per 100 person-years (95% confidence interval : 17.8, 20.3) in women and 20.9 per 100 person-years (95% confidence interval: 19.2, 22.8) in men. Cognitive function and all measures of functional status declined with age; these changes were similar by sex. When we isolated period effects, we found that medication use increased over time. These estimates can help inform future research and can help health-care systems meet the needs of this growing population.

The genetic component of human longevity: New insights from the analysis of pathway-based SNP-SNP interactions

In human longevity studies, single nucleotide polymorphism (SNP) analysis identified a large number of genetic variants with small effects, yet not easily replicable in different populations. New insights may come from the combined analysis of different SNPs, especially when grouped by metabolic pathway. We applied this approach to study the joint effect on longevity of SNPs belonging to three candidate pathways, the insulin/insulin‐like growth factor signalling (IIS), DNA repair and pro/antioxidant. We analysed data from 1,058 tagging SNPs in 140 genes, collected in 1825 subjects (1,089 unrelated nonagenarians from the Danish 1905 Birth Cohort Study and 736 Danish controls aged 46–55 years) for evaluating synergic interactions by SNPsyn. Synergies were further tested by the multidimensional reduction (MDR) approach, both intra‐ and interpathways. The best combinations (FDR<0.0001) resulted those encompassing IGF1R‐rs12437963 and PTPN1‐rs6067484, TP53‐rs2078486 and ERCC2‐rs50871, TXNRD1‐rs17202060 and TP53‐rs2078486, the latter two supporting a central role of TP53 in mediating the concerted activation of the DNA repair and pro‐antioxidant pathways in human longevity. Results were consistently replicated with both approaches, as well as a significant effect on longevity was found for the GHSR gene, which also interacts with partners belonging to both IIS and DNA repair pathways (PAPPA,PTPN1,PARK7, MRE11A). The combination GHSR‐MREA11, positively associated with longevity by MDR, was further found influencing longitudinal survival in nonagenarian females (p = .026). Results here presented highlight the validity of SNP‐SNP interactions analyses for investigating the genetics of human longevity, confirming previously identified markers but also pointing to novel genes as central nodes of additional networks involved in human longevity.

Resting Heart Rate Is Not Associated with Cognitive Function

AIMS

In order to examine the hypothesis that elevated resting heart rate (RHR) is associated with impaired cognitive score, we investigated the relationship between RHR and cognitive score in middle-aged, elderly and old Danish subjects from the general population.

METHODS

Composite cognitive scores derived from the result of 5 age-sensitive cognitive tests for a total of 7,002 individuals (Middle-aged Danish twin: n = 4,132, elderly Danish twins: n = 2,104 and Danish nonagenarian: n = 766) divided according to RHR and compared using linear regression models adjusted for sex, age, previous heart conditions and hypertension. RHR was assessed by palpating radial pulse. Genetic and shared environmental confounding was addressed in intrapair analyses of 2,049 twin pairs.

RESULTS

In unadjusted multivariate models and in multivariable models adjusting for age, sex, heart conditions and hypertension, RHR was not associated with cognitive function. Furthermore, the intrapair analyses showed that RHR was not associated with cognitive score testing within twin pairs, as measured by the proportion of twin pairs in which the twin with higher RHR also was the twin with the lowest composite cognitive score (1,049 pairs of 2,049 pairs [51% (95% CI 49-53), p < 0.289]).

CONCLUSION

While elevated RHR has been shown to be associated with adverse health events and poor fitness level, RHR has no relation to cognitive function in the general population.

Investigation of the 5q33.3 longevity locus and age-related phenotypes

A large meta-analysis recently found the 5q33.3 locus to be associated with survival to ≥ 90 years and lower all-cause mortality, thus suggesting it as a third human longevity locus alongside APOE and FOXO3A. The 5q33.3 locus has previously been associated with blood pressure regulation and cardiovascular diseases in middle-aged individuals. However, part of the influence on mortality appears to be independent of cardiovascular phenotypes, and the role of the 5q33.3 locus in longevity and survival is therefore still partly unknown. We investigated the association between the longevity-associated variant rs2149954 on chromosome 5q33.3 and age-related phenotypes in two cohorts of 1,588 and 1,271 long-lived individuals (mean ages 93.1 and 95.9 years, respectively) as well as in 700 middle-aged and 677 elderly individuals (mean ages 52.5 and 78.7 years). Altogether, nominally significant associations between the rs2149954 minor allele and a decreased risk of heart attack and heart failure as well as increased physical functioning were found in the long-lived individuals. In the middle-aged and elderly individuals, rs2149954 minor allele carriers had a lower risk of hypertension. Our results thereby confirm a role of the 5q33.3 locus in cardiovascular health and, interestingly, they also suggest a role in physical functioning.

Life at Age 100: An International Research Agenda for Centenarian Studies

Living a long life is desired by many individuals, and this dream is likely to become reality in more and more industrialized societies. During the past 3 decades, the number of very old individuals has increased significantly, creating a global demographic challenge with consequences at the individual, family, and societal levels. Yet, life in very old age is still poorly understood in terms of its unique characteristics and challenges. Besides specific content areas, very old age represents an understudied field of research. This lack of knowledge may be one reason that the very old also are an underserved population. This special issue introduces an international network of three centenarian studies that describe and compare the life circumstances and characteristics of centenarians across Germany, Portugal, and the United States. Our parallel studies comprehensively assess centenarians' physical, cognitive, social, and psychological functioning to create a knowledge base regarding their capacities and needs. A specific focus lies in the investigation of psychological aspects, social resources, and societal/cultural contexts, factors that may contribute to longevity and successful aging. Determining key characteristics of this very old population and investigating similarities and differences across countries is timely and urgent, both from an applied and a policy standpoint.

Changes in Drug Use and Polypharmacy After the Age of 90: A Longitudinal Study of the Danish 1905 Cohort

OBJECTIVES

To determine the longitudinal development of drug use in very old adults.

DESIGN

Longitudinal cohort study with waves in 1998, 2000, 2002, and 2005.

SETTING

Nationwide study in Denmark.

PARTICIPANTS

All living Danes born in 1905 were approached in 1998; 2,262 responded at baseline.

MEASUREMENTS

Self-reported use of regularly taken drugs. Mean and median number of drugs and growth curve models were used to identify the change in number of drugs as the cohort aged from 92 to 100.

RESULTS

The within-person use of drugs increased with age for women (0.19 per year; 95% confidence interval (CI) = 0.15-0.24) and men (0.15 per year; 95% CI = 0.06-0.24). Persons leaving the study prematurely had higher baseline values and a steeper increase in their annual use of drugs. The population-level mean number of drugs increased from baseline (3.6 drugs) to the first follow-up (4.1 drugs) but thereafter remained stable at approximately 4 drugs. Women used more drugs than men at all waves.

CONCLUSION

In this first longitudinal study of drug use in nonagenarians, individuals used an increasing number of drugs as they aged. This increase is difficult to detect in cross-sectional analyses of the population-level mean. More efforts to understand what is reasonable prescribing at these older ages are needed.

Cognitive Functioning after Surgery in Middle-aged and Elderly Danish Twins

BACKGROUND

Postoperative cognitive dysfunction is common, but it remains unclear whether there are long-term adverse cognitive effects of surgery combined with anesthesia. The authors examined the association between exposure to surgery and level of cognitive functioning in a sample of 8,503 middle-aged and elderly twins.

METHODS

Results from five cognitive tests were compared in twins exposed to surgery, classified as major, minor, hip and knee replacement, or other, with those of a reference group without surgery using linear regression adjusted for sex and age. Genetic and shared environmental confounding was addressed in intrapair analyses of 87 monozygotic and 124 dizygotic same-sexed twin pairs in whom one had a history of major surgery and the other did not.

RESULTS

Statistically significantly lower composite cognitive score was found in twins with at least one major surgery compared with the reference group (mean difference, -0.27; 95% CI, -0.48 to -0.06), corresponding to one tenth of an SD, that is, a negligible effect size. In the intrapair analysis, the surgery-exposed co-twin had the lower cognitive score in 49% (95% CI, 42 to 56%) of the pairs. None of the other groups differed from the reference group except the knee and hip replacement group that tended to have higher cognitive scores (mean difference, 0.35; 95% CI, -0.18 to 0.87).

CONCLUSIONS

A history of major surgery was associated with a negligibly lower level of cognitive functioning. The supplementary analyses suggest that preoperative cognitive functioning and underlying diseases were more important for cognitive functioning in mid- and late life than surgery and anesthesia.

Survival Prognosis in Very Old Adults

OBJECTIVES

To determine whether simple functional indicators are predictors of survival prognosis in very old adults.

DESIGN

In-person survey conducted over a 3-month period in 1998; assessment of survival over a 15-year follow-up period.

SETTING

Denmark.

PARTICIPANTS

All 3,600 Danes born in 1905 and living in Denmark in 1998, were invited to participate regardless of residence and health; 2,262 (63%) participated in the survey: 1,814 (80.2%) in person and 448 (19.8%) through a proxy.

MEASUREMENTS

Socioeconomic factors, medications and diseases, activities of daily living, physical performance, cognition, depression symptomatology, self-rated health, and all-cause mortality, evaluated as average remaining lifespan and chance of surviving to 100 years.

RESULTS

Men aged 92 to 93 had an overall 6.0% chance of surviving to 100 years, whereas the chance for women was 11.4%. Being able to rise without use of hands increased the chance for men to 11.2% (95% confidence interval (CI)=7.7-14.7) and for women to 22.0% (95% CI=18.9-25.1). When combining this with a Mini-Mental State Examination (MMSE) scores from 28 to 30, the chances were 21.7% (95% CI=11.5-31.9) for men and 34.2% (95% CI=24.8-43.5) for women.

CONCLUSION

Chair stand score combined with MMSE score is a quick and easy way to estimate overall chance of survival in very old adults, which is particularly relevant when treatment with potential side effects for nonacute diseases is considered.

No Association between Variation in Longevity Candidate Genes and Aging-related Phenotypes in Oldest-old Danes

In this study we explored the association between aging-related phenotypes previously reported to predict survival in old age and variation in 77 genes from the DNA repair pathway, 32 genes from the growth hormone 1/ insulin-like growth factor 1/insulin (GH/IGF-1/INS) signalling pathway and 16 additional genes repeatedly considered as candidates for human longevity: APOE, APOA4, APOC3, ACE, CETP, HFE, IL6, IL6R, MTHFR, TGFB1, SIRTs 1, 3, 6; and HSPAs 1A, 1L, 14. Altogether, 1,049 single nucleotide polymorphisms (SNPs) were genotyped in 1,088 oldest-old (age 92-93 years) Danes and analysed with phenotype data on physical functioning (hand grip strength), cognitive functioning (mini mental state examination and a cognitive composite score), activity of daily living and self-rated health. Five SNPs showed association to one of the phenotypes; however, none of these SNPs were associated with a change in the relevant phenotype over time (7 years of follow-up) and none of the SNPs could be confirmed in a replication sample of 1,281 oldest-old Danes (age 94-100). Hence, our study does not support association between common variation in the investigated longevity candidate genes and aging-related phenotypes consistently shown to predict survival. It is possible that larger sample sizes are needed to robustly reveal associations with small effect sizes.

Copy number variation associates with mortality in long-lived individuals: a genome-wide assessment

Copy number variants (CNVs) represent a significant source of genetic variation in the human genome and have been implicated in numerous diseases and complex traits. To date, only a few studies have investigated the role of CNVs in human lifespan. To investigate the impact of CNVs on prospective mortality at the extreme end of life, where the genetic component of lifespan appears most profound, we analyzed genomewide CNV data in 603 Danish nonagenarians and centenarians (mean age 96.9 years, range 90.0–102.5 years). Replication was performed in 500 long‐lived individuals from the Leiden Longevity Study (mean age 93.2 years, range 88.9–103.4 years). First, we assessed the association between the CNV burden of each individual (the number of CNVs, the average CNV length, and the total CNV length) and mortality and found a significant increase in mortality per 10 kb increase in the average CNV length, both for all CNVs (hazard ratio (HR) = 1.024, P = 0.002) and for duplications (HR = 1.011, P = 0.005), as well as per 100 kb increase in the total length of deletions (HR = 1.009, P = 0.0005). Next, we assessed the relation between specific deletions and duplications and mortality. Although no genome–wide significant associations were discovered, we identified six deletions and one duplication that showed consistent association with mortality in both or either of the sexes across both study populations. These results indicate that the genome–wide CNV burden, specifically the average CNV length and the total CNV length, associates with higher mortality in long‐lived individuals.

Genetic Variants in KLOTHO Associate With Cognitive Function in the Oldest Old Group

Decline in cognitive abilities is a major concern in aging individuals. A potential important factor for functioning of the central nervous system in late-life stages is the KLOTHO (KL) gene. KL is expressed in various organs including the brain and is involved in multiple biological processes, for example, growth factor signaling. In the present study, 19 tagging gene variants in KL were studied in relation to 2 measures of cognitive function, a 5-item cognitive composite score and the Mini Mental State Examination, in 1,480 Danes 92-100 years of age. We found that heterozygotes for the previously reported KL-VS had poorer cognitive function than noncarriers. Two other variants positioned in the 5' end of the gene, rs398655 and rs562020, were associated with better cognitive function independently of KL-VS, and the common haplotype AG was associated with poorer cognition, consistently across two cognitive measures in two cohort strata. The haplotype effect was stronger than that of KL-VS. Two variants, rs2283368 and rs9526984, were the only variants significantly associated with cognitive decline over 7 years. We discuss an age-dependent effect of KL and the possibility that multiple gene variants in KL are important for cognitive function among the oldest old participants.

Health and function assessments in two adjacent Danish birth cohorts of centenarians: Impact of design and methodology

Using the results from measures of functional ability, cognitive and physical performance from two adjacent birth cohorts of 100-year-old adults, we aimed to elucidate the possible impact of difference in participation rates, design, and interviewer mode. Participants were birth cohort members born in 1910 (DK-1910) and 1911-12 (DK-1911). Both surveys used the same assessment instruments, but the design was different, and data collection was carried out by trained survey agency interviewers in DK-1910 and trained nurses in DK-1911. Participation rate in DK-1911 (49.8 % (251/504)) was lower than in DK-1910 (66.9 % (273/408)) (p < 0.001). The proportion of interviews with the participant answering alone or mainly alone was significantly higher in DK-1911 (77 %) than in DK-1910 (56 %), and the proportion living in nursing home was significantly lower (44 vs. 54 %, respectively). Higher proportions of DK-1911 independently performed all activities of daily living (ADL) compared to DK-1910, but only significantly for toileting, bathing, and feeding (all p < 0.01). Mini-mental state examination (MMSE) score was higher in DK-1911 than in DK-1910 (23.5 vs. 21.0; p < 0.001). Handgrip strength, gait speed, and chair stand were almost similar. DK-1911 participants had significantly better one-year survival than DK-1911 non-participants and DK-1910 participants and non-participants (p = 0.001). These results suggest that lower participation rate entails selection towards healthier participants in terms of ADL and cognitive functioning. Caution is warranted when comparing studies of centenarians with different participation rates, design, and interviewer mode, and further studies of these methodological issues are required.

The APP A673T frequency differs between Nordic countries

A coding gene variant A673T (rs63750847) in the APP gene has recently been recognized as a protective variant of late-onset Alzheimer's Disease in a large Icelandic population and has been observed recurrently in populations from Nordic countries. The variant also was related to longevity in the Icelandic population. However, because of the extreme rarity of A673T in non-Nordic populations, the association with Alzheimer's disease has not yet been formally replicated. Because the variant has not been reported among the Danes, we aimed to study its frequency among healthy middle-age twins and oldest-old singletons and explore the possible effects on longevity and cognitive abilities. Surprisingly, only 1 of 3487 unrelated Danes carried the A673T variant, (0.014% [95% CI 0.000-0.080]), which was significantly lower than in the other Nordic countries averaging to 0.43% (95% CI 0.40-0.46). In conclusion, the A673T variant is rarer in Danes than other Nordic countries, thus precluding assessment of association with longevity or cognitive functioning.

[The NonaSantfeliu study. Baseline assessment and ten years of follow-up]

NonaSantfeliu study: A review is presented of the studies that are part of the initial overall assessment and the studies performed during the 10 years of follow-up of a cohort of nonagenarians. It is a population-based study of 186 subjects, 76.5% women, mean age at baseline of 93.06 years, a quarter (26%) being institutionalized. The mean of baseline Barthel index was 60.8, and the mean for the Lobo's cognitive minimental was 21. Nonagenarian males with low comorbidity had more successful aging criteria than women with high comorbidity quantified with the Charlson Index. The survival rate at 10 years follow-up was very low, and 95.6% of the population had died. This represented an annual mortality rate of 9.5%. A common denominator on assessing all different annual cuts, is that the most important factors associated with mortality are those related to geriatric assessment, such as a function, cognition, dementia, and cumulative comorbidity and multiple medications, compared to more traditional risk factors described in younger populations.

Is the adiposity-associated FTO gene variant related to all-cause mortality independent of adiposity? Meta-analysis of data from 169,551 Caucasian adults

Previously, a single nucleotide polymorphism (SNP), rs9939609, in the FTO gene showed a much stronger association with all-cause mortality than expected from its association with body mass index (BMI), body fat mass index (FMI) and waist circumference (WC). This finding implies that the SNP has strong pleiotropic effects on adiposity and adiposity-independent pathological pathways that leads to increased mortality. To investigate this further, we conducted a meta-analysis of similar data from 34 longitudinal studies including 169,551 adult Caucasians among whom 27,100 died during follow-up. Linear regression showed that the minor allele of the FTO SNP was associated with greater BMI (n = 169,551; 0.32 kg m(-2) ; 95% CI 0.28-0.32, P < 1 × 10(-32) ), WC (n = 152,631; 0.76 cm; 0.68-0.84, P < 1 × 10(-32) ) and FMI (n = 48,192; 0.17 kg m(-2) ; 0.13-0.22, P = 1.0 × 10(-13) ). Cox proportional hazard regression analyses for mortality showed that the hazards ratio (HR) for the minor allele of the FTO SNPs was 1.02 (1.00-1.04, P = 0.097), but the apparent excess risk was eliminated after adjustment for BMI and WC (HR: 1.00; 0.98-1.03, P = 0.662) and for FMI (HR: 1.00; 0.96-1.04, P = 0.932). In conclusion, this study does not support that the FTO SNP is associated with all-cause mortality independently of the adiposity phenotypes.

Do postal health surveys capture morbidity and mortality in respondents aged 65 years and older? A register-based validation study

Aims: Non-response to population surveys is a common problem in epidemiological and public health research. Systematic non-response threatens the validity of results. Researchers rarely evaluate the magnitude of systematic non-response because of limited access to population data. This study explores how well morbidity and mortality in postal survey respondents aged 65 years and older represented that of the target population. Methods: The 2010 Stockholm Public Health Survey and the Swedish Population Register were linked to the Cause of Death Register and the National Patient Register in Sweden. Differences were analysed between the response group and the corresponding population in mortality, hospital admission, days spent in hospital and number of diagnoses. Finally, data were weighted for non-response to see if this improved generalizability. Results: Non-response increased with age, and this increase was more pronounced among women than men. Respondents were marginally less often admitted to hospital, hospitalized fewer days and had slightly fewer diagnoses than the population, in particular after age 80. Significantly fewer women died in the response group than in the population as a whole. In terms of mortality among men and in terms of hospitalizations for most age groups, the respondents represented the population fairly well. Non-response weighting adjustment did not improve generalizability. Conclusions: Postal questionnaires are likely to capture morbidity (hospitalization) among women and men aged 65-80 years old and mortality among men, while morbidity after age 80 and mortality in women are likely to be underestimated.

Association study of FOXO3A SNPs and aging phenotypes in Danish oldest-old individuals

FOXO3A variation has repeatedly been reported to associate with human longevity, yet only few studies have investigated whether FOXO3A variation also associates with aging-related traits. Here, we investigate the association of 15 FOXO3A tagging single nucleotide polymorphisms (SNPs) in 1088 oldest-old Danes (age 92-93) with 4 phenotypes known to predict their survival: cognitive function, hand grip strength, activity of daily living (ADL), and self-rated health. Based on previous studies in humans and foxo animal models, we also explore self-reported diabetes, cancer, cardiovascular disease, osteoporosis, and bone (femur/spine/hip/wrist) fracture. Gene-based testing revealed significant associations of FOXO3A variation with ADL (P = 0.044) and bone fracture (P = 0.006). The single-SNP statistics behind the gene-based analysis indicated increased ADL (decreased disability) and reduced bone fracture risk for carriers of the minor alleles of 8 and 10 SNPs, respectively. These positive directions of effects are in agreement with the positive effects on longevity previously reported for these SNPs. However, when correcting for the test of 9 phenotypes by Bonferroni correction, bone fracture showed borderline significance (P = 0.054), while ADL did not (P = 0.396). Although the single-SNP associations did not formally replicate in another study population of oldest-old Danes (n = 1279, age 94-100), the estimates were of similar direction of effect as observed in the Discovery sample. A pooled analysis of both study populations displayed similar or decreased sized P-values for most associations, hereby supporting the initial findings. Nevertheless, confirmation in additional study populations is needed.

DCAF4, a novel gene associated with leucocyte telomere length

BACKGROUND

Leucocyte telomere length (LTL), which is fashioned by multiple genes, has been linked to a host of human diseases, including sporadic melanoma. A number of genes associated with LTL have already been identified through genome-wide association studies. The main aim of this study was to establish whether DCAF4 (DDB1 and CUL4-associated factor 4) is associated with LTL. In addition, using ingenuity pathway analysis (IPA), we examined whether LTL-associated genes in the general population might partially explain the inherently longer LTL in patients with sporadic melanoma, the risk for which is increased with ultraviolet radiation (UVR).

RESULTS

Genome-wide association (GWA) meta-analysis and de novo genotyping of 20 022 individuals revealed a novel association (p=6.4×10(-10)) between LTL and rs2535913, which lies within DCAF4. Notably, eQTL analysis showed that rs2535913 is associated with decline in DCAF4 expressions in both lymphoblastoid cells and sun-exposed skin (p=4.1×10(-3) and 2×10(-3), respectively). Moreover, IPA revealed that LTL-associated genes, derived from GWA meta-analysis (N=9190), are over-represented among genes engaged in melanoma pathways. Meeting increasingly stringent p value thresholds (p<0.05, <0.01, <0.005, <0.001) in the LTL-GWA meta-analysis, these genes were jointly over-represented for melanoma at p values ranging from 1.97×10(-169) to 3.42×10(-24).

CONCLUSIONS

We uncovered a new locus associated with LTL in the general population. We also provided preliminary findings that suggest a link of LTL through genetic mechanisms with UVR and melanoma in the general population.

Physical and mental decline and yet rather happy? A study of Danes aged 45 and older

OBJECTIVES

Little is known about whether the feeling of happiness follows the age-related decline in physical and mental functioning. The objective of this study was to analyze differences with age in physical and mental functions and in the feeling of happiness among Danes aged 45 years and older.

METHOD

Three Danish population-based surveys including 11,307 participants aged 45+ years, of whom 2411 were in the age group of 90+, were conducted in the period 1995-2001. The participation rate in the three surveys was between 63% and 82% and the same design and the same instrument were used. Self-reported mobility, a cognitive composite score, and a depression symptomatology score including a question about happiness were assessed. T-score metric was used to compare across domains and age groups.

RESULTS

Overall, successively older age groups performed worse than the youngest age group (45-49 years), and the estimated linear decline was greater after age 70 than before age 70. For example, when comparing the oldest age group (90+ years) with the youngest, the T-score differences were found to be the largest for the mobility score (men: 40.2, women: 41.4), followed by the cognitive function (men: 22.0, women: 24.9), and the total depression symptomatology score (men: 15.5, women: 17.4). Conversely, the T-score difference in happiness was small (men: 5.6, women: 6.0).

CONCLUSION

Despite markedly poorer physical and mental functions with increasing age, in this Danish sample age did not seem to affect happiness to a similarly notable extent, although, in this study, cohort and age effects cannot be disentangled.

Birth cohort differences in the prevalence of longevity-associated variants in APOE and FOXO3A in Danish long-lived individuals

Gene variants found to associate with human longevity in one population rarely replicate in other populations. The lack of consistent findings may partly be explained by genetic heterogeneity among long-lived individuals due to cohort differences in survival probability. In most high-income countries the probability of reaching e.g. 100years increases by 50-100% per decade, i.e. there is far less selection in more recent cohorts. Here we investigate the cohort specificity of variants in the APOE and FOXO3A genes by comparing the frequencies of the APOE ε4 allele and the minor alleles of two variants in FOXO3A at age 95+ and 100+ in 2712 individuals from the genetically homogeneous Danish birth cohorts 1895-96, 1905, 1910-11, and 1915. Generally, we find a decrease in the allele frequencies of the investigated APOE and FOXO3A variants in individuals from more recent birth cohorts. Assuming a recessive model, this negative trend is significant in 95+ year old individuals homozygous for the APOE ε4 allele (P=0.026) or for the FOXO3A rs7762395 minor allele (P=0.048). For the APOE ε4 allele, the significance is further strengthened when restricting to women (P=0.006). Supportive, but non-significant, trends are found for two of the three tested variants in individuals older than 100years. Altogether, this indicates that cohort differences in selection pressure on survival to the highest ages are reflected in the prevalence of longevity gene variants. Although the effect seems to be moderate, our findings could have an impact on genetic studies of human longevity.

Adjustment for smoking does not alter the FOXO3A association with longevity

Human longevity is a multifactorial phenotype influenced by both genetic and environmental factors. Despite its heritability of 25-32 %, the genetic background of longevity is as yet largely unexplained. Apart from APOE status, variation in the FOXO3A gene is the only confirmed genetic contributor to survival into old age. On the other hand, FOXO3A activity is known to be downregulated in various cancers, and the gene was recently identified as a novel deletion hotspot in human lung adenocarcinoma. In view of the strong association between smoking and lung cancer, we set out to explore whether smoking modifies the known association between FOXO3A variation and longevity. To this end, we conducted a case-control study in two different populations, drawing upon extensive collections of old-aged individuals and younger controls available to us (1,613 German centenarians/nonagenarians and 1,104 controls; 1,088 Danish nonagenarians and 736 controls). In the German sample, 21 single nucleotide polymorphisms (SNPs) from the FOXO3A gene region were genotyped, whereas 15 FOXO3A SNPs were analyzed in the Danish sample. Eight SNPs were typed in both populations. Logistic regression analysis revealed that adjustment for smoking does not systematically alter the association between FOXO3A variation and longevity in neither population. Our analysis therefore suggests that the said association is not largely due to the confounding effects of lung cancer.

Health status and 6 years survival of 552 90+ Italian sib-ships recruited within the EU Project GEHA (GEnetics of Healthy Ageing)

In a scenario of increasing life expectancy worldwide, it is mandatory to identify the characteristics of a healthy aging phenotype, including survival predictors, and to disentangle those related to environment/lifestyle versus those related to familiarity/genetics. To this aim we comprehensively characterised a cohort of 1,160 Italian subjects of 90 years and over (90+, mean age 93 years; age range 90-106 years) followed for 6 years survival, belonging to 552 sib-ships (familiar longevity) recruited (2005-2008) within the EU-funded GEHA project in three Italian geographic areas (Northern, Central and Southern Italy) different for urban/rural and socio-economical characteristics. On the whole, the following factors emerged as significant predictors of survival after 90 years of age: absence of cognitive impairment and physical disability, high hand grip strength scores and body mass index (BMI) values, "excellent/good" self-reported health, high haemoglobin and total cholesterol levels and low creatinine levels. These parameters, excluding BMI values, were also significantly associated within sib-ships, suggesting a strong familial/genetic component. Geographical micro-heterogeneity of survival predictors emerged, such as functional and physical status being more important in Southern than in Central and Northern Italy. In conclusion, we identified modifiable survival predictors related to specific domains, whose role and importance vary according to the geographic area considered and which can help in interpreting the genetic results obtained by the GEHA project, whose major aim is the comprehensive evaluation of phenotypic and genetic data.

Human longevity and variation in DNA damage response and repair: study of the contribution of sub-processes using competitive gene-set analysis

DNA-damage response and repair are crucial to maintain genetic stability, and are consequently considered central to aging and longevity. Here, we investigate whether this pathway overall associates to longevity, and whether specific sub-processes are more strongly associated with longevity than others. Data were applied on 592 SNPs from 77 genes involved in nine sub-processes: DNA-damage response, base excision repair (BER), nucleotide excision repair, mismatch repair, non-homologous end-joining, homologous recombinational repair (HRR), RecQ helicase activities (RECQ), telomere functioning and mitochondrial DNA processes. The study population was 1089 long-lived and 736 middle-aged Danes. A self-contained set-based test of all SNPs displayed association with longevity (P-value=9.9 × 10(-5)), supporting that the overall pathway could affect longevity. Investigation of the nine sub-processes using the competitive gene-set analysis by Wang et al indicated that BER, HRR and RECQ associated stronger with longevity than the respective remaining genes of the pathway (P-values=0.004-0.048). For HRR and RECQ, only one gene contributed to the significance, whereas for BER several genes contributed. These associations did, however, generally not pass correction for multiple testing. Still, these findings indicate that, of the entire pathway, variation in BER might influence longevity the most. These modest sized P-values were not replicated in a German sample. This might, though, be due to differences in genotyping procedures and investigated SNPs, potentially inducing differences in the coverage of gene regions. Specifically, five genes were not covered at all in the German data. Therefore, investigations in additional study populations are needed before final conclusion can be drawn.

Indoor mobility-related fatigue and muscle strength in nonagenarians: a prospective longitudinal study

BACKGROUND AND AIMS

Mobility-related fatigue is an important indicator of functional decline in old age, however, very little is known about fatigue in the oldest old population segment. The aim of this study was to examine the association between indoor mobility-related fatigue and muscle strength decline in nonagenarians.

METHODS

The study is based on a prospective longitudinal study of all Danes born in 1905 and assessed in 1998, 2000 and 2003, and includes 92- to 93-year-old persons who were independent of help in basic indoor mobility at baseline (n = 1,353). Fatigue was assessed at baseline and defined as a subjective feeling of fatigue when transferring or walking indoors. The outcome measure, maximum grip strength, was measured at each measurement point.

RESULTS

Grip strength declined throughout the study in participants with and without fatigue, but those reporting fatigue had significantly (P < .001) lower muscle strength during the entire study period. Longitudinal analyses indicated slightly slower decline in muscle strength among participants with fatigue compared to those without; however, observed selective dropout of participants with fatigue and poor performance at baseline needs to be considered when interpreting the results. Accordingly, participants without fatigue had significantly higher chances of being alive and having muscle strength above gender-specific median at first (RR 1.32, 95 % CI 1.07-1.58), second (RR 1.51, 1.06-1.96) and third (RR 1.39, 1.01-1.97) measurement points.

CONCLUSIONS

Indoor mobility-related fatigue in advanced later life should not merely be considered as an unpleasant symptom, but rather an indicator of physical impairment, and consequently declined physiological reserve.

Best lung function equations for the very elderly selected by survival analysis

We evaluated which equations best predicted the lung function of a cohort of nonagenarians based on which best accounted for subsequent survival. In 1998, we measured lung function, grip strength and dementia score (Mini Mental State Examination (MMSE)) in a population-based sample of 2262 Danes born in 1905. Mortality was registered to 2011 when only five (0.2%) subjects were alive. In half the cohort, we recorded forced expiratory volume in 1 s (FEV1). Complete data were available in 592 subjects with results expressed as standardised residuals (SR) using various prediction equations. Cox proportional hazard regression found lower FEV1SR was a predictor of mortality having controlled for MMSE, grip strength and sex. The US National Health and Nutrition Examination Survey (NHANES) III (1999) equations gave a better spread of median survival by FEV1SR quartile: 3.94, 3.65, 3.51 and 2.61 years with a hazard ratio for death of 1, 1.16, 1.32 and 1.60 respectively, compared with equations derived with the inclusion of elderly subjects. We conclude that extrapolating from NHANES III equations to predict lung function in nonagenarians gave better survival predictions from spirometry than when employing equations derived using very elderly subjects with possible selection bias. These findings can help inform how future lung function equations for the elderly are derived.

The Mugello study, a survey of nonagenarians living in Tuscany: design, methods and participants' general characteristics

BACKGROUND

Previous studies on nonagenarians have widely investigated functional and cognitive decline, falls, predictors of mortality, inflammation and aging genetics. However, some intriguing domains, such as body composition, daily energy expenditure, sleep quality and physical activity, as well as endothelial progenitor cells and "omics" fields, such as proteomics or metabolomics, have been poorly explored. In this preliminary paper we report design, methods and characteristics of participants in the Mugello Study, a survey of nonagenarians aimed at filling these gaps.

METHODS

475 non selected nonagenarians, 130 men and 345 women, mean age 92.6 years ± SD 2.6, received a visit by a trained physician at their residence. Along with the assessment of social, functional and cognitive status, reported in this paper, participants also underwent instrumental examinations, including body impedance assessment and continuous direct calorimetry, and were administered a series of validated questionnaires. Further, 385 participants accepted to undergo blood withdrawal.

RESULTS

In 52 cases the visit was conducted in nursing homes. Among the 423 home-living participants, 91 lived alone and 77 were not looked after by any caregiver. Altogether, 154 participants over 475 were free from disabilities and 266 showed Mini Mental State Examination raw scores ≥ 21. Men showed less disability and cognitive impairment (p<0.001, for both).

CONCLUSIONS

As a whole, our findings are comparable to those reported in other surveys. Future studies, by using the Mugello Study database and biologic bank, that will be available to all researchers, will shed some more light on the aging process in nonagenarians.

CLU genetic variants and cognitive decline among elderly and oldest old

The CLU gene is one of the prime genetic candidates associated with Alzheimers disease. In the present study CLU genotypes and haplotypes were associated with baseline cognition and the rate of cognitive decline in two cohorts, the Danish 1905 birth cohort (93 years of age in 1998) and the Longitudinal Study of Aging Danish twins (LSADT) (73-83 year old twins in 1997). Both Mini Mental State Examination (MMSE) and a cognitive composite score was attained up to six times for up to 10 years and analysed using random effects models and vital status. The rs11136000 T allele was associated with better baseline cognitive performance both in the LSADT (effect on intercept: 0.41 95% CI [-0.04; 0.87]) and the 1905 birth cohort (effect on intercept: 0.28 95% CI [0.01; 0.55]), although it did not reach significance in the LSADT cohort. However, the rs11136000 T allele was significantly associated with a steeper decline (effect on slope: -0.06 95% CI [-0.11; -0.01]) in the LSADT cohort, but not in the 1905 birth cohort. Haplotype analyses revealed that carriers of the common rs11136000, rs1532278 and rs9331888 TTC haplotype (36%) in the CLU gene performed cognitively better than non-carriers in the 1905 birth cohort (effect on intercept: 0.50 95% CI [0.12; 0.91]) and carriers of a rare TCC haplotype (1%) performed worse on the cognitive composite score (effect on intercept: -1.51 95% CI [-2.92; -0.06]). The association between the TTC haplotype and better cognitive composite score was higher among those surviving past the age of 98 (p = 0.014), and among these the TTC haplotype was borderline associated with a steep decline (effect on slope: -0.13 95% CI [-0.27; 0.00]). In summery CLU genetic variants associate with cognition in two cohorts, but the genetic effect of CLU seems to regress toward the mean when aging.

Optimism and survival: does an optimistic outlook predict better survival at advanced ages? A twelve-year follow-up of Danish nonagenarians

BACKGROUND AND AIMS

Studies examining predictors of survival among the oldest-old have primarily focused on objective measures, such as physical function and health status. Only a few studies have examined the effect of personality traits on survival, such as optimism. The aim of this study was to examine whether an optimistic outlook predicts survival among the oldest-old.

METHODS

The Danish 1905 Cohort Survey is a nationwide, longitudinal survey comprising all individuals born in Denmark in 1905. At baseline in 1998, a total of 2,262 persons aged 92 or 93 agreed to participate in the intake survey. The baseline in-person interview consisted of a comprehensive questionnaire including physical functioning and health, and a question about whether the respondent had an optimistic, neutral or pessimistic outlook on his or her own future.

RESULTS

During the follow-up period of 12 years (1998-2010) there were 2,239 deaths (99 %) in the 1905 Cohort Survey. Univariable analyses revealed that optimistic women and men were at lower risk of death compared to their neutral counterparts [HR 0.82, 95 % CI (0.73-0.93) and 0.81, 95 % CI (0.66-0.99), respectively]. When confounding factors such as baseline physical and cognitive functioning and disease were taken into account the association between optimism and survival weakened in both sexes, but the general pattern persisted. Optimistic women were still at lower risk of death compared to neutral women [HR 0.85, 95 % CI (0.74-0.97)]. The risk of death was also decreased for optimistic men compared to their neutral counterparts, but the effect was non-significant [HR 0.91, 95 % CI (0.73-1.13)].

CONCLUSION

An optimistic outlook appears to be a significant predictor of survival among the oldest-old women. It may also be a significant predictor for men but the sample size is small.

Musculoskeletal pain and physical functioning in the oldest old

BACKGROUND

Little is known about the impact of pain on physical functioning among the oldest-old subjects. In this study, we first examined the associations between the number of painful sites and measures of physical functioning reflecting different stages of the disablement process (physical impairment, functional limitation and disability) among nonagenarians (more than ninety years old persons). Second, we described the effect of painful sites on disability during a 2-year follow-up period.

METHODS

This study is based on baseline (n = 1177) and 2-year follow-up (n = 709) data of the nationwide Danish 1905 cohort study. Musculoskeletal pain was assessed as reported pain in back, hips or knees when moving or resting. Physical performance measures included maximum grip strength and habitual walking speed. Disability in performing activities of daily living was defined as the need for assistive device or personal help in transferring, dressing, washing, using toilet and/or walking indoors.

RESULTS

At baseline, the number of painful sites was significantly associated with measured grip strength and walking speed as well as self-reported disability in a stepwise manner; the more sites with pain, the poorer the physical functioning. The follow-up analyses showed corresponding but slightly weaker stepwise associations between baseline pain and disability level at follow-up, and indicated that although on the whole, single or multi-site pain did not predict the onset of disability, multi-site pain increased the risk of developing severe disability.

CONCLUSIONS

The findings of this study suggest that musculoskeletal pain in nonagenarians is highly prevalent and is associated with poor physical performance and disability.

Is self-rated health still sensitive for changes in disease and functioning among nonagenarians?

OBJECTIVES

With age, there is an increasing gap between relatively stable levels of self-rated health (SRH) and actual health status. This study investigates longitudinal changes in SRH and examines its sensitivity to changes in chronic conditions and functioning among people aged 90 and older.

METHODS

In the Vitality 90+ Study, questionnaires were sent to all people aged 90 years and older living in Tampere, Finland. Included were respondents who provided data on the 2001 measurement and at least one follow-up measurement in 2003, 2007, or 2010 (N = 334). Generalized Estimating Equations analyses examined longitudinal change in SRH and the predictive value of number of chronic conditions and a functioning score based on 5 activities.

RESULTS

Within 2 years, most people (56.3%) had unchanged SRH, but declined SRH (22.3%) was associated with worse baseline functioning and declined functioning. Clear declines in SRH after 6 and 9 years were associated with increased chronic conditions (odds ratio [OR] = 1.23) and decreased functioning (OR = 1.28). The impact of chronic conditions and functioning was smaller among institutionalized people (chronic conditions OR = 0.90; functioning OR = 1.18) than among people living independently (chronic conditions OR = 1.30; functioning OR = 1.44).

DISCUSSION

SRH among nonagenarians was sensitive to changes in the number of chronic conditions and functioning although more pronounced on the longer than on the shorter term.

A novel permutation test for case-only analysis identifies epistatic effects on human longevity in the FOXO gene family

Genetic interactions or epistasis could make a substantial contribution to variation in human complex traits including longevity. However, detecting epistatic interactions in high dimensional datasets is difficult due to various reasons including multiple testing of correlated tests. We introduce a novel permutation strategy to the case-only analysis of gene-by-gene interaction using multiple SNPs. The method is applied to genes coding for Forkhead box O transcription factors which recently have been associated with human longevity across different populations hypothesizing that epistatic interaction in the regulation and expression of the FOXO gene family could contribute to the human longevity phenotype. Genotype data were collected from 1088 individuals from the Danish 1905 birth cohort aged over 92-93 years with 12 SNPs in the FOXO1a and 15 SNPs in the FOXO3a genes. Our analysis detected a joint effect between rs9486902 in FOXO3a and rs2701858 in FOXO1a that highly significantly contributes to human longevity (OR = 3.23, 95% CI: 2.93-3.53) which is consistent in both males and females. Our results were compared with published studies, and importance of our novel method and findings was discussed.

Evidence from case-control and longitudinal studies supports associations of genetic variation in APOE, CETP, and IL6 with human longevity

In this study, we investigated 102 single-nucleotide polymorphisms (SNPs) covering the common genetic variation in 16 genes recurrently regarded as candidates for human longevity: APOE; ACE; CETP; HFE; IL6; IL6R; MTHFR; TGFB1; APOA4; APOC3; SIRTs 1, 3, 6; and HSPAs 1A, 1L, 14. In a case-control study of 1,089 oldest-old (ages 92-93) and 736 middle-aged Danes, the minor allele frequency (MAF) of rs769449 (APOE) was significantly decreased in the oldest-old, while the MAF of rs9923854 (CETP) was significantly enriched. These effects were supported when investigating 1,613 oldest-old (ages 95-110) and 1,104 middle-aged Germans. rs769449 was in modest linkage equilibrium (R (2)=0.55) with rs429358 of the APOE-ε4 haplotype and adjusting for rs429358 eliminated the association of rs769449, indicating that the association likely reflects the well-known effect of rs429358. Gene-based analysis confirmed the effects of variation in APOE and CETP and furthermore pointed to HSPA14 as a longevity gene. In a longitudinal study with 11 years of follow-up on survival in the oldest-old Danes, only one SNP, rs2069827 (IL6), was borderline significantly associated with survival from age 92 (P-corrected=0.064). This advantageous effect of the minor allele was supported when investigating a Dutch longitudinal cohort (N=563) of oldest-old (age 85+). Since rs2069827 was located in a putative transcription factor binding site, quantitative RNA expression studies were conducted. However, no difference in IL6 expression was observed between rs2069827 genotype groups. In conclusion, we here support and expand the evidence suggesting that genetic variation in APOE, CETP, and IL6, and possible HSPA14, is associated with human longevity.

Cardiovascular diseases are largely underreported in Danish centenarians

BACKGROUND

the substantial decline in oldest old mortality has led to more people surviving to very old age. As morbidity and disability generally increases with age epidemiological research in ageing has focused on the health of oldest olds. However, most studies are based on self-reported or physician-reported information, not objective health information.

OBJECTIVE

to estimate and compare the prevalence of cardiovascular diseases (CVDs) in Danish centenarians using three different sources of information: self-reported, physician-reported and objective data.

DESIGN

the population-based clinical-epidemiological study of 100-year-old Danes.

METHODS

all eligible participants were interviewed (self-report) in their domicile and offered a clinical examination, including an electrocardiogram (ECG) and blood pressure measurement. Further health information was retrieved from general practitioners' medical files and the Danish National Discharge Register (physician report).

RESULTS

out of 276 eligible, 207 (75%) participated. Blood pressure and ECG were measured in 76 and 69%, respectively. There was poor agreement between self-reported and physician-reported CVDs, and between physician-reported CVDs and clinical objective CVD diagnoses. Only angina pectoris reached a Kappa value of 0.5. ECG revealed twice as many cases of myocardial infarction and ischaemia compared with physician-reported. Using both physician-reported and ECG 95 (46%) of the centenarians suffered from at least one of the diseases myocardial infarction, angina pectoris or atrial fibrillation. Adding physician-reported heart failure and hypertension increased the prevalence of CVD to 80%.

CONCLUSION

self-reported information largely underestimates the CVD life-time prevalence in Danish centenarians. Objective clinical examinations are necessary to evaluate true disease prevalence in oldest old.

Identifying the genomic determinants of aging and longevity in human population studies: progress and challenges

Human lifespan variation is mainly determined by environmental factors, whereas the genetic contribution is 25–30% and expected to be polygenic. Two complementary fields go hand in hand in order to unravel the mechanisms of biological aging: genomic and biomarker research. Explorative and candidate gene studies of the human genome by genetic, transcriptomic, and epigenomic approaches have resulted in the identification of a limited number of interesting positive linkage regions, genes, and pathways that contribute to lifespan variation. The possibilities to further exploit these findings are rapidly increasing through the use of novel technologies, such as next-generation sequencing. Genomic research is progressively being integrated with biomarker studies on aging, including the application of (noninvasive) deep phenotyping and omics data – generated using novel technologies – in a wealth of studies in human populations. Hence, these studies may assist in obtaining a more holistic perspective on the role of the genome in aging and lifespan regulation.

Effects of the APOE ε2 allele on mortality and cognitive function in the oldest old

Some studies indicate that the APOE ε2 allele may have a protective effect on mortality and mental health among the elderly adults. We investigated the effect of the APOE ε2 allele on cognitive function and mortality in 1651 members of the virtually extinct Danish 1905 birth cohort. We found no protective effect of the APOE ε2 allele on mortality compared with the APOE ε3 allele. The point estimates indicated an increased protection against cognitive decline over time for persons with the APOE ε2 allele. Cognitive score did not significantly modify the mortality risk of the various APOE genotypes. We did not find a protective effect of the APOE ε2 allele on mortality among the oldest old, but in agreement with our previous findings, we found a 22% increased mortality risk for APOE ε4 carriers. The APOE ε2 allele may be protective on cognitive decline among the oldest old.

AKT1 fails to replicate as a longevity-associated gene in Danish and German nonagenarians and centenarians

In addition to APOE and FOXO3, AKT1 has recently been suggested as a third consistent longevity gene, with variants in AKT1 found to be associated with human lifespan in two previous studies. Here, we evaluated AKT1 as a longevity-associated gene across populations by attempting to replicate the previously identified variant rs3803304 as well as by analyzing six additional AKT1 single-nucleotide polymorphisms, thus capturing more of the common variation in the gene. The study population was 2996 long-lived individuals (nonagenarians and centenarians) and 1840 younger controls of Danish and German ancestry. None of the seven SNPs tested were significantly associated with longevity in either a case-control or a longitudinal setting, although a supportive nominal indication of a disadvantageous effect of rs3803304 was found in a restricted group of Danish centenarian men. Overall, our results do not support AKT1 as a universal longevity-associated gene.

Analyzing age-specific genetic effects on human extreme age survival in cohort-based longitudinal studies

The analysis of age-specific genetic effects on human survival over extreme ages is confronted with a deceleration pattern in mortality that deviates from traditional survival models and sparse genetic data available. As human late life is a distinct phase of life history, exploring the genetic effects on extreme age survival can be of special interest to evolutionary biology and health science. We introduce a non-parametric survival analysis approach that combines population survival information with individual genotype data in assessing the genetic effects in cohort-based longitudinal studies. Our approach is characterized by non-parametric analysis of late age survival to capture the observed pattern of mortality deceleration and frailty modeling to account for individual heterogeneity in unobserved frailty. The method is applied to ApoE genotype data in the Danish 1905 birth cohort to estimate effect of the e4 allele. Our results revealed an age-specific relative risk of the allele that increases nonlinearly with age and non-proportional patterns in hazard of death for carriers and non-carriers of the allele, suggesting that the e4 mutation preserves its deleterious effect that progressively affect human survival even at extreme ages.

UCP3 polymorphisms, hand grip performance and survival at old age: association analysis in two Danish middle aged and elderly cohorts

An efficient uncoupling process is generally considered to have a protective effect on the aging muscle by slowing down its age-related decay. Genetic polymorphisms in the Uncoupling Protein 3 (UCP3) gene, whose product is mainly expressed in skeletal muscle, were suggested to be associated with hand grip (HG) performances in elderly populations. Considering the population specificity of the quality of aging, we aimed to add further support to this evidence by analyzing the association between four SNPs in the UCP3 gene and relative haplotypes in two large cohorts of middle aged (N=708) and oldest old Danes (N=908). We found that the variability at rs1685354 and rs11235972 was associated with HG levels both at single and haplotypic level in both cohorts. Furthermore, taking advantage of large cohort and period survival data of the oldest cohort, we tested the association of each SNP with survival at 10years from the baseline visit. Interestingly, we found that allele A at rs11235972, associated in this cohort with lowest HG scores, influences also the survival patterns, with people carrying this allele showing higher mortality rates. On the whole, our work supports the role of UCP3 gene in functional status and survival at old age.

Fatigability in basic indoor mobility in nonagenarians

OBJECTIVES

To evaluate the prevalence and associated health factors of indoor mobility-related fatigability in nonagenarians.

DESIGN

A cross-sectional observational study of all Danes born in 1905 and assessed in 1998.

SETTING

Community, sheltered housing and nursing homes.

PARTICIPANTS

Individuals aged 92 and 93 (N = 1,181) who were independent of help in basic indoor mobility.

MEASUREMENTS

Fatigability in basic indoor mobility was defined as a subjective feeling of fatigue when transferring or walking indoors. Other standardized assessments include self-report measures of medical history and performance-based assessments of walking speed and maximum handgrip strength.

RESULTS

Twenty-six percent of participants reported fatigability when transferring or walking indoors; fatigability was more common in participants living in sheltered housing (32%) than in those living independently (23%, P < .001). Cardiovascular diseases, musculoskeletal pain, medications, walking speed, and depressive symptoms were independently associated with fatigability.

CONCLUSION

Fatigability in basic everyday mobility is common in nondisabled nonagenarians. The results also indicate important associations between fatigability and potentially modifiable health factors.

Frailty phenotypes in the elderly based on cluster analysis: a longitudinal study of two Danish cohorts. Evidence for a genetic influence on frailty

Frailty is a physiological state characterized by the deregulation of multiple physiologic systems of an aging organism determining the loss of homeostatic capacity, which exposes the elderly to disability, diseases, and finally death. An operative definition of frailty, useful for the classification of the individual quality of aging, is needed. On the other hand, the documented heterogeneity in the quality of aging among different geographic areas suggests the necessity for a frailty classification approach providing population-specific results. Moreover, the contribution of the individual genetic background on the frailty status is still questioned. We investigated the applicability of a cluster analysis approach based on specific geriatric parameters, previously set up and validated in a southern Italian population, to two large longitudinal Danish samples. In both cohorts, we identified groups of subjects homogeneous for their frailty status and characterized by different survival patterns. A subsequent survival analysis availing of Accelerated Failure Time models allowed us to formulate an operative index able to correlate classification variables with survival probability. From these models, we quantified the differential effect of various parameters on survival, and we estimated the heritability of the frailty phenotype by exploiting the twin pairs in our sample. These data suggest the presence of a genetic influence on the frailty variability and indicate that cluster analysis can define specific frailty phenotypes in each population.

Genetic variation in TERT and TERC and human leukocyte telomere length and longevity: a cross-sectional and longitudinal analysis

Telomerase is of key importance for telomere maintenance, and variants of the genes encoding its major subunits, telomerase reverse transcriptase (TERT) and telomerase RNA component (TERC), are candidates for interindividual variation in telomere length. Recently, the two SNPs rs3772190 and rs12696304 in the TERC locus were reported to be associated with leukocyte telomere length (LTL) in two genome-wide association studies, while one haplotype of TERT (rs2853669, rs2736098, rs33954691, and rs2853691) has been reported to be associated with both LTL and longevity in a candidate gene study. In this study, we investigated the two TERC and four TERT SNPs in middle-aged, old, and oldest-old Danes (58-100 years) and their association with LTL (n = 864) and longevity (n = 1069). Furthermore, data on 11 TERT tagging SNPs in 1089 oldest-old and 736 middle-aged Danes were investigated with respect to longevity. For all SNPs, the association with longevity was investigated using both a cross-sectional and a longitudinal approach. Applying an additive model, we found association of LTL with the minor TERC alleles of rs3772190 (A) and rs12696304 (G), such that a shorter LTL was seen in rs3772190 A carriers (regression coefficient = -0.08, P = 0.011) and in male rs12696304 G carriers (regression coefficient = -0.13, P = 0.014). No TERT variations showed association. Moreover, the A allele of rs3772190 (TERC) was found to be associated with longevity [hazard rate (AG + AA) = 1.31, P = 0.006]. No associations with longevity were observed for the TERT SNPs or haplotypes. Our study, thus, indicates that TERC is associated with both LTL and longevity in humans.