Genetic influences on life span and survival among elderly African-Americans, Caribbean Hispanics, and Caucasians

The accelerated aging phenotype: The role of race and social determinants of health on aging

The pursuit to discover the fundamental biology and mechanisms of aging within the context of the physical and social environment is critical to designing interventions to prevent and treat its complex phenotypes. Aging research is critically linked to understanding health disparities because these inequities shape minority aging, which may proceed on a different trajectory than the overall population. Health disparities are characteristically seen in commonly occurring age-associated diseases such as cardiovascular and cerebrovascular disease as well as diabetes mellitus and cancer. The early appearance and increased severity of age-associated disease among African American and low socioeconomic status (SES) individuals suggests that the factors contributing to the emergence of health disparities may also induce a phenotype of 'premature aging' or 'accelerated aging' or 'weathering'. In marginalized and low SES populations with high rates of early onset age-associated disease the interaction of biologic, psychosocial, socioeconomic and environmental factors may result in a phenotype of accelerated aging biologically similar to premature aging syndromes with increased susceptibility to oxidative stress, premature accumulation of oxidative DNA damage, defects in DNA repair and higher levels of biomarkers of oxidative stress and inflammation. Health disparities, therefore, may be the end product of this complex interaction in populations at high risk. This review will examine the factors that drive both health disparities and the accelerated aging phenotype that ultimately contributes to premature mortality.

A Comparison of Variances in Age Cohorts to Understand Longevity in African Americans

BACKGROUND

African American life expectancy at age 65 is about 2 years less than that of Caucasians, but by age 85, African Americans may have a longevity advantage. One possible explanation for this cross-over effect is that African Americans who make it to the oldest ages have done so by handling stressful contextual and health disadvantages. The purpose of this study was to examine possible within group cohort differences that lead to exceptional longevity among older African Americans.

METHODS

Data came from three cohorts of older African Americans: the Carolina African American Twin Study of Aging (CAATSA), the Baltimore Study of Black Aging-Patterns of Cognitive Aging (BSBA-PCA), and the Study of Longevity and Stress in African American Families (SOLSAA). Of the 533 participants, we compared two age cohorts (60-79 and 80+) with an average age of 73.2 (SD = 8.33) and 26.3% are men. Variables included measures of stress, depression, coping, cognition, and health indicators.

RESULTS

The variance for depression and average peak expiratory flow (APEF) was significantly larger for the older cohort but after controlling for demographic factors, the measure of depressive symptoms was not. The Alpha Span test showed a significant difference with the older cohort having larger variances after controlling for demographic factors.

CONCLUSIONS

The findings suggest that there are changes in the characteristics of who makes it to later life, but counter to our hypothesis, there was greater variability in the oldest group relative to the younger.

Regional Distribution of Longevity Population and Elements in Drinking Water in Jiangjin District, Chongqing City, China

In order to determine the spatial variation of longevity population and elements contained in the drinking water of longevity region in Jiangjin and investigate the relationship between the elements in drinking water and longevity, population censuses on township level and 98 drinking water samples from Jiangjin District, Chongqing City in West China were collected and analyzed. Population statistics on township level showed that the number of centenarians per 100,000 inhabitants (OC), centenarity index (CI), and number of centenarians per 10,000 over 65-year-old subjects (UC) present obvious geographic distribution properties, generally Central region > Northern region > Southern region (Kruskal-Wallis test, p < 0.05). Moderate hard water (150 mg/L < total hardness (TH) = 156.17 mg/L < 300 mg/L) was mainly found in drinking water from longevity township (OC > 7.5) in Jiangjin District, whereas soft water (75 mg/L < TH = 111.23 mg/L < 150 mg/L) was mostly in non-longevity township (OC < 7.5). The mean concentration of strontium (Sr) (0.73 mg/L) in drinking water from the longevity township was apparently higher than that of non-longevity township (0.44 mg/L) (Mann-Whitney U test, p = 0.019 < 0.05). The concentrations of Ba, Li, Mn, Ni, and Se in drinking water from longevity township were also higher than those of non-longevity township (Mann-Whitney U test, p < 0.05). The research indicates that exercising strict control over the concentrations of TH, Sr, Ba, Li, Mn, Ni, and Se in drinking water might be good for the health and prolong people's life.

Expression patterns of cardiac aging in Drosophila

Aging causes cardiac dysfunction, often leading to heart failure and death. The molecular basis of age-associated changes in cardiac structure and function is largely unknown. The fruit fly, Drosophila melanogaster, is well-suited to investigate the genetics of cardiac aging. Flies age rapidly over the course of weeks, benefit from many tools to easily manipulate their genome, and their heart has significant genetic and phenotypic similarities to the human heart. Here, we performed a cardiac-specific gene expression study on aging Drosophila and carried out a comparative meta-analysis with published rodent data. Pathway level transcriptome comparisons suggest that age-related, extra-cellular matrix remodeling and alterations in mitochondrial metabolism, protein handling, and contractile functions are conserved between Drosophila and rodent hearts. However, expression of only a few individual genes similarly changed over time between and even within species. We also examined gene expression in single fly hearts and found significant variability as has been reported in rodents. We propose that individuals may arrive at similar cardiac aging phenotypes via dissimilar transcriptional changes, including those in transcription factors and micro-RNAs. Finally, our data suggest the transcription factor Odd-skipped, which is essential for normal heart development, is also a crucial regulator of cardiac aging.

Regional distribution of longevity population and chemical characteristics of natural water in Xinjiang, China

Xinjiang Province, China is recognized for the longevity of its inhabitants. To study the temporal and spatial variation of longevity region and chemical characteristics of natural water of longevity region in Xinjiang, three population censuses on county-level and 51 natural water samples from Hotan Prefecture, Xinjiang were collected and analyzed. 103 natural water samples were collected from the public papers. Population statistics on county-level showed that the number of centenarians per 100,000 inhabitants (OC) in Southern Xinjiang was 7.4(year 1990), 4.9(year 2000) and 2.1 times (year 2010) more than that of Northern Xinjiang, respectively. And distribution of the longevity index (LI%), centenarity index (CI%) and number of centenarians per 10,000 over 65 year-old subjects (UC) on county-level decreased from south to north. Natural water in Northern Xinjiang was mainly fresh soft water, and it was mainly fresh hard water and brackish hard water in Southern Xinjiang. Water quality of natural water in Northern Xinjiang was superior compare to that of Southern Xinjiang, while number of centenarians 65 year-old & over per 10,000 subjects in Northern Xinjiang were less than that of Southern Xinjiang before 2010. The research indicates that keeping on drinking water with high total hardness (TH) and Mg/Ca ratio might be good for the health.

Parental brevity linked to cardiometabolic risk in diabetic descendants

BACKGROUND

Non-diabetic offspring from long-lived parents benefit from lowered CV risk. No study investigated the effects of parental lifespan on their progeny when offspring have T2DM. This study assessed CV and metabolic features of T2DM offspring according to parental lifespan.

PATIENTS & METHODS

558 T2DM patients were questioned on parental longevity (paternal and/or maternal lifespan ≥ 80 years); mean age 66 (11) years; male:female 66:34; divided into 6 groups: long-lived father [LLF] (n = 143); short-lived father [SLF] (n = 262); long-lived mother [LLM] (n = 229); short-lived mother [SLM] (n = 176); long-lived father and long-lived mother [LLF & LLM] (n = 82); and short-lived father and/or short-lived mother [SLF &/or SLM] (n = 323).

RESULTS

Age was similar in [LLF & LLM] and [SLF &/or SLM]. Diabetes duration was longer in [SLF &/or SLM] (p 0.0073). Body composition, hypertension, hepatic steatosis and metabolic syndrome (MetS) were similar in both groups, [SLF &/or SLM] having a higher MetS score: 3.79 (1.12) vs. 3.48 (1.12) (p 0.0257). Fasting insulinemia was higher in [SLF &/or SLM] (p 0.0001), who were more insulin resistant (+10%: p 0.0440). HbA1c was higher (+0.36%) in [SLF &/or SLM] (p 0.0138). LDL-C; non-HDL-C; and apoB100 were similar in both groups, whereas HDL-C and apoA-I were higher in [LLF & LLM] (p 0.0233 and p 0.0179). Prevalence and severity of atherogenic dyslipidemia were raised in [SLF &/or SLM], by 53% (prevalence) and 13% (log[TG]/HDL-C) (p 0.0172 and p 0.0067).

CONCLUSION

Bilateral reductions in parental longevity are linked to unfavorable cardiometabolic phenotype in T2DM descendants, with worsened insulin resistance and atherogenic dyslipidemia among 1st-degree offspring.

Genome wide association and linkage analyses identified three loci-4q25, 17q23.2, and 10q11.21-associated with variation in leukocyte telomere length: the Long Life Family Study

Leukocyte telomere length is believed to measure cellular aging in humans, and short leukocyte telomere length is associated with increased risks of late onset diseases, including cardiovascular disease, dementia, etc. Many studies have shown that leukocyte telomere length is a heritable trait, and several candidate genes have been identified, including TERT, TERC, OBFC1, and CTC1. Unlike most studies that have focused on genetic causes of chronic diseases such as heart disease and diabetes in relation to leukocyte telomere length, the present study examined the genome to identify variants that may contribute to variation in leukocyte telomere length among families with exceptional longevity. From the genome wide association analysis in 4,289 LLFS participants, we identified a novel intergenic SNP rs7680468 located near PAPSS1 and DKK2 on 4q25 (p = 4.7E-8). From our linkage analysis, we identified two additional novel loci with HLOD scores exceeding three, including 4.77 for 17q23.2, and 4.36 for 10q11.21. These two loci harbor a number of novel candidate genes with SNPs, and our gene-wise association analysis identified multiple genes, including DCAF7, POLG2, CEP95, and SMURF2 at 17q23.2; and RASGEF1A, HNRNPF, ANF487, CSTF2T, and PRKG1 at 10q11.21. Among these genes, multiple SNPs were associated with leukocyte telomere length, but the strongest association was observed with one contiguous haplotype in CEP95 and SMURF2. We also show that three previously reported genes-TERC, MYNN, and OBFC1-were significantly associated with leukocyte telomere length at p empirical < 0.05.

The search for longevity and healthy aging genes: insights from epidemiological studies and samples of long-lived individuals

Genetic factors clearly contribute to exceptional longevity and healthy aging in humans, yet the identification of the underlying genes remains a challenge. Longevity is a complex phenotype with modest heritability. Age-related phenotypes with higher heritability may have greater success in gene discovery. Candidate gene and genome-wide association studies (GWAS) for longevity have had only limited success to date. The Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium conducted a meta-analysis of GWAS data for longevity, defined as survival to age 90 years or older, that identified several interesting associations but none achieved genome-wide significance. A recent GWAS of longevity conducted in the Leiden Longevity Study identified the ApoE E4 isoform as deleterious to longevity that was confirmed in an independent GWAS of long-lived individuals of German descent. Notably, no other genetic loci for longevity have been identified in these GWAS. To examine the conserved genetic mechanisms between the mouse and humans for life span, we mapped the top Cohorts for Heart and Aging Research in Genomic Epidemiology GWAS associations for longevity to the mouse chromosomal map and noted that eight of the ten top human associations were located within a previously reported mouse life-span quantitative trait loci. This work suggests that the mouse and human may share mechanisms leading to aging and that the mouse model may help speed the understanding of how genes identified in humans affect the biology of aging. We expect these ongoing collaborations and the translational work with basic scientists to accelerate the identification of genes that delay aging and promote a healthy life span.

Biological V. Social Definitions of Race: Implications for Modern Biomedical Research

Misconceptions concerning the concordance of biological and social definitions of race are ongoing in American society. This problem extends beyond that of the lay public into the professional arena, especially that of biomedical research. This continues, in part, because of the lack of training of many biomedical practitioners in evolutionary thinking. This essay reviews the biological and social definitions of race, examining how understanding the evolutionary mechanisms of disease is crucial to addressing ongoing health disparities. Finally it concludes by laying bear the fallacies of “race-specific” medicine.

Interactive association of heat shock protein 70 genes variants with natural longevity in Xinjiang Hetian Uygur ethnicity

Mounting evidence suggests that all organisms at the cellular level respond to stress by synthesizing heat shock proteins at the expense of other proteins, and the ability of human cells to respond to heat stress decreases with aging. We thus investigate the association of 3 variants (A1267G in HSPA1B, G190C in HSPA1A, and T2437C in HSPA1L) in the heat shock protein 70 (Hsp70) family with natural longevity in a Xinjiang Hetian Uygur population. A case-control study was conducted in 191 healthy individuals greater than 90 years of age, and 53 naturally died persons 65-70 years of age. Promoter activity was evaluated by luciferase reporter assays. The data were analyzed using an EH/EH+ program for haplotype prediction and MDR software for gene-gene interaction. All studied variants satisfied the Hardy-Weinberg equilibrium in each group. In single-locus analysis, no significant differences were found between long-lived people and short-lived people in the genotype/allele distributions of all variants. In contrast, haplotype analysis indicated that haplotypes A-G-C and A-C-T were more prevalent in long-lived people than short-lived people (P=0.026 and 0.017), and the analysis conferred a 3.46- and 4.51-fold increased tendency for longevity, respectively (P=0.025 and 0.016). The haplotype results were strengthened by interaction analysis, which suggests an optimal model in which G190C and T2437C exert an interacting effect on longevity. No functional significance was observed between 190G and 190C alleles in both control and heat-inducible A549 cells (P>0.05). Taken together, our findings suggested that common genetic variants in Hsp70 family might contribute interactively to longevity the Xinjiang Hetian Uygur population.

Genetic epidemiology in aging research

Over the last two decades, aging research has expanded to include not only age-related disease models, and conversely, longevity and disease-free models, but also focuses on biological mechanisms related to the aging process. By viewing aging on multiple research frontiers, we are rapidly expanding knowledge as a whole and mapping connections between biological processes and particular age-related diseases that emerge. This is perhaps most true in the field of genetics, where variation across individuals has improved our understanding of aging mechanisms, etiology of age-related disease, and prediction of therapeutic responses. A close partnership between gerontologists, epidemiologists, and geneticists is needed to take full advantage of emerging genome information and technology and bring about a new age for biological aging research. Here we review current genetic findings for aging across both disease-specific and aging process domains. We then highlight the limitations of most work to date in terms of study design, genomic information, and trait modeling and focus on emerging technology and future directions that can partner genetic epidemiology and aging research fields to best take advantage of the rapid discoveries in each.

Comparison of short scales to measure depressive symptoms in elders with diabetes

Depression is the most common mental health problem among American elders and it is also prevalent among those with diabetes. The 20-item Center for Epidemiological Studies Depression Scale (CES-D) is commonly used to measure depressive symptoms in elders, but its length is potentially burdensome. Twelve short forms of the CES-D (4 to 16 items) exist, but they have not been tested with elders with diabetes. This study compared reliability and validity estimates across the 12 short forms and investigated similarities in classifying elders with diabetes as clinically depressed using standardized cut scores. Beck's theory provides a framework for identifying the affective, cognitive, behavioral, and somatic symptoms that are measured by the CES-D. Data were merged from two studies, which yielded 80 elders with diabetes who completed the CES-D items during structured interviews. Cronbach's alpha was .87 for the CES-D; it ranged from .60 (5 items) to .84 (16 items) for shorter forms. Correlations of the full CES-D and short forms ranged from .82 (4 items) to .98 (16 items). Using the CES-D cut score, 14% of the elders with diabetes had clinically significant depressive symptoms: 21% men, 11% women, 17% African Americans, and 13% Caucasians. A 5-item scale overestimated 29% as clinically depressed: 33% men, 27% women, 25% African Americans, and 29% Caucasians. The findings suggest that shortened scales to measure depressive symptoms may be potentially useful with elders with diabetes. Further psychometric studies of the CES-D short forms are recommended with elders with chronic conditions.

Analysis of common polymorphisms in angiotensin-converting enzyme and apolipoprotein e genes and human longevity in Colombia

BACKGROUND

Genetic analysis of human longevity may be useful for the understanding of molecular mechanisms implicated in age-related diseases. The molecular genetics of human longevity is largely unexplored in Latin American populations and other developing countries.

METHODS

To explore the possibility of an association of common polymorphisms in two candidate genes and longevity in Colombia, we analyzed two polymorphisms in apolipoprotein E (APOE) and angiotensin-converting enzyme (ACE) genes in a sample of 538 Colombian subjects (18-106 years), using previously validated PCR-based methodologies.

RESULTS

We found a significant decrease in ACE DD genotype (24 vs. 16%) between young and old subject groups (mean age: 45 vs. 77 years) (p = 0.03). The ACE DD genotype and D allele decrease was significant only in women. There were no differences for APOE polymorphism between young and old subjects.

CONCLUSIONS

Our results are compatible with the expected age-related decrease of ACE DD genotype. Future studies examining functional single nucleotide polymorphisms (SNPs) in the ACE gene and its correlation with serum ACE activity in the older subjects and their younger relatives in this sample are warranted.

Gene regulation for the senescence marker protein DHEA-sulfotransferase by the xenobiotic-activated nuclear pregnane X receptor (PXR)

Dehydroepiandrosterone (DHEA)-sulfotransferase (SULT2A1) is a phase II metabolizing/detoxifying enzyme with substrate preference for physiological hydroxysteroids, diverse drugs and other xenobiotics. The first-pass tissues (liver and intestine) express SULT2A1 at high levels. In senescent male rodents, Sult2A1 gene transcription in the liver is markedly enhanced and calorie restriction retards this increase. Age-associated loss of the liver expression of androgen receptor in part explains the up-regulation of Sult2A1 expression at late life, since androgen receptor is a negative regulator of this gene. In line with its role in xenobiotic metabolism, the Sult2A1 gene is induced by the pregnane X receptor (PXR). PXR is a xenosensing nuclear receptor that is activated by endobiotic (natural steroids) and xenobiotic (therapeutic drugs and environmental chemicals) molecules. An inverted-repeat arrangement (IR0) of the consensus half site binding sequence for nuclear receptors mediates the xenobiotic induction of the Sult2A1 promoter. The IR0 element is a specific binding site for PXR and its heterodimer partner retinoid X receptor (RXR-alpha) and it directs PXR-mediated induction of a heterologous promoter. In contrast to the loss of androgen receptor expression, PXR and RXR-alpha mRNA expression is invariant during aging. Repression by the androgen receptor and induction by PXR may act coordinately to cause the senescence associated and xenobiotic mediated stimulation of Sult2A1 transcription. Increased Sult2A1 expression appears to be an adaptive response to ensure optimal metabolism of Sult2A1 substrates at old age.