Understanding retirement: the promise of life-span developmental frameworks.
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ABSTRACT:
SUBMITTER: Lockenhoff CE
PROVIDER: S-EPMC5549194 | biostudies-other | 2012 Sep
REPOSITORIES: biostudies-other
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Project description:Evidence from different sources shows that spouses' retirement decisions are correlated. Retirement policies affecting individuals in couples are therefore also likely to affect behavior of their spouses. It is therefore important to account for joint features in modeling retirement. This paper studies a structural collective model of labor supply and retirement of both partners in a couple with interdependent preferences, imperfect knowledge of preferences of the spouse, and subjective expectations about the future. We propose a novel method to estimate preferences and the intra-household bargaining process, which relies on stated preferences data collected in the Health and Retirement Study. Respondents were asked to choose between hypothetical retirement trajectories describing the retirement ages and replacement rates of both spouses from three perspectives: considering their own preferences only, the preferences of their spouse only, or the most likely decision for the household. With these data, all model parameters are identified and potential sources of joint retirement can be disentangled. Our results suggest that males misperceive their wives' preferences, overestimating their disutility of work. Our estimates correct for this. We find strong positive correlations between preferences for joint leisure (leisure complementarity) of the two partners. Counterfactual simulations with stylized retirement paths suggest that the leisure complementarities explain a substantial part of joint retirement, much more than correlation in unobserved heterogeneity or potential wage rates.
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Project description:Integration/differentiation of mental processes is major mechanism of development. Developmental theories ascribe intellectual development to it. In psychometric theory, Spearman's law of diminishing returns postulates that increasing g allows increasing differentiation of cognitive abilities, because increased mental power allows variable investment in domain-specific learning. Empirical evidence has been inconsistent so far, with some studies supporting and others contradicting this mechanism. This state of affairs is due to a developmental phenomenon: Both differentiation and strengthening of relations between specific processes and g may happen but these changes are phase-specific and ability-specific, depending upon the developmental priorities in the formation of g in each phase. We present eight studies covering the age span from 4 to 85 years in support of this phenomenon. Using new powerful modeling methods we showed that differentiation and binding of mental processes in g occurs in cycles. Specific processes intertwine with g at the beginning of cycles when they are integrated into it; when well established, these processes may vary with increasing g, reflecting its higher flexibility. Representational knowledge, inductive inference and awareness of it, and grasp of logical constraints framing inference are the major markers of g, first intertwining with in their respective cycles and differentiating later during the periods of 2-6, 7-11, and 11-20 years, respectively. The implications of these findings for an overarching cognitive developmental/differential theory of human mind are discussed.
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Project description:ABSTRACT MAGWIRE, MICHAEL MAHLON. Mutations Increasing Drosophila melanogaster Life Span. (Under the direction of Trudy F. C. Mackay.) Better living conditions and advances in medicine have made it possible for humans to live considerably longer than before. This has uncovered many health problems associated with age. By identifying genes involved in the limitation of life span, we may better understand the processes that lead to aging. In model organisms, we can use mutagenesis to discover mutations that increase life span, and hence infer that the wild-type allele limits life span by some means. We have assessed longevity in a collection of 1332 co-isogenic gene-trap P-element insertion lines and determined changes in life span of each insert line relative to the corresponding control line. Significant lines were determined via two different methods of analysis: A 95% confidence interval was established based on deviations of the mutant life spans from the controls and Dunnett’s two tailed t-tests were used to examine differences between mutant and control in each individual block. Based on the 95% confidence interval, 139 inserts displayed an increase in life span and 194 inserts a decrease. Using Dunnett’s, 70 lines increased in life span, while 270 decreased in life span. An additional 48 increased longevity lines were close enough to meeting Dunnett’s criteria to be considered for additional investigation. Combining these two analyses, we chose 83 inserts associated with increased life span for a secondary screen using an additional twelve replicates. 58 of these lines remained significant. We have determined the P-element insertion site for 50 of these lines. Starvation resistance, chill coma recovery time and climbing activity were measured on the lines remaining significant after the the secondary screen to identify pleiotropic effects. A positive correlation was found for males between life span and starvation resistance as well as between life span and chill coma recovery. Females only displayed a correlation between life span and chill coma recovery, which was negative. None of the lines indicated increased fitness for all phenotypes, indicating there may be some type of trade-off. There also appears to be a lot of pleiotropic variation depending on background and sex. Ten of the lines, all with the same parental background, were chosen for a half-diallel cross to identify epistasis between the mutants. There were substantial epistatic interactions between all ten lines. Furthermore, males and females displayed vastly different patterns of epistasis, again indicating major differences in life span regulation between the sexes. Finally, a subset of seven of the lines used in the epistatic study, in addition to the corresponding parental control, were chosen for microarray analysis to look for possible pathways and novel genes involved in increasing life span. 1,996 probe sets were significant at a false discovery rate q-value threshold of q < 0.0001. Tukeys tests were carried out for these probe sets to determine how each of the seven mutant backgrounds differed compared to the control and each other. In addition, each mutant background was compared individually with the control to identify any changes in expression. Gene ontologies were determined for each of the lines to identify over-represented biological functions which would indicate possible longevity pathways. Dozens of pathways were suggested, including several novel pathways. Keywords: Genetic (P-element insertion) modification and comparison to control line
2008-08-01 | GSE8775 | GEO
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Project description:It remains unclear whether retirement circumstances are associated with better or worse post-retirement health. This is partly due to confounding between measures of retirement circumstances and a tendency to account only for covariates around retirement age. The present study examined the contributions of both retirement age and retirement type, independently, to post-retirement health around age 77 years. It also examined whether these contributions remain once earlier life-course factors - social class, cognitive ability and education - were accounted for. Our sample was 742 Scottish people who took part in the Scottish Mental Survey 1947. In a path model including life-course predictors, retirement type (reason), but not age, significantly predicted post-retirement health, with ill-health retirement associated with poorer physical (β = 0.455, 95% CI [0.313, 0.597], p < 0.001) and mental health (β = 0.339, 95% CI [0.191, 0.486], p < 0.001), and redundancy retirement associated with poorer physical health only (β = 0.200, 95% CI [0.069, 0.331], p = 0.004). Of the life-course predictors, higher adult social class was associated with later retirement (β = 0.115, 95% CI [0.034, 0.196], p = 0.006) and higher childhood cognitive ability was associated with increased odds of voluntary retirement (OR = 1.054, 95% CI [1.005, 1.105], p = 0.032), but no indirect contribution to health (mediated by retirement circumstances) was significant. At the same time, higher childhood cognitive ability directly predicted better post-retirement physical health (β = -0.110, 95% CI [-0.216, -0.004], p = 0.041), independently of retirement circumstances. This study demonstrates the importance of considering retirement circumstances beyond age, and of accounting for confounding between retirement circumstances and earlier life-course factors.
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Project description:In the present study, we tested the antioxidant activity of phycoerythrin (PE, an oligomeric light harvesting protein isolated from Lyngbya sp. A09DM) to curtail aging effects in Caenorhabditis elegans. Purified PE (100 ?g/ml) dietary supplement was given to C. elegans and investigated for its anti-aging potential. PE treatment improved the mean life span of wild type (N2)-animals from 15?±?0.1 to 19.9?±?0.3 days. PE treatment also moderated the decline in aging-associated physiological functions like pharyngeal pumping and locomotion with increasing age of N2 worms. Moreover, PE treatment also enhanced the stress tolerance in 5-day-aged adults with increase in mean survival rate from 22.2?±?2.5 to 41.6?±?2.5% under thermo stress and from 30.1?±?3.2 to 63.1?±?6.4% under oxidative (hydrogen peroxide)-stress. PE treatment was also noted to moderate the heat-induced expression of human amyloid-beta(A?1-42) peptide and associated paralysis in the muscle tissues of transgenic C. elegans CL4176 (Alzheimer's disease model). Effectiveness of PE in expanding the life span of mutant C. elegans, knockout for some up (daf-2 and age-1)- and down (daf-16)-stream regulators of insulin/IGF-1 signaling (IIS), shows the independency of PE effect from DAF-2-AGE-1-DAF-16 signaling pathway. Moreover, the inability of PE in expanding the life span of hsf-1 knockout C. elegans(sy441) suggests the dependency of PE effect on heat shock transcription factor (HSF-1) controlling stress-induced gene expression. In conclusion, our results demonstrated a novel anti-aging activity of PE which conferred increased resistance to cellular stress resulting in improved life span and health span of C. elegans.
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2008-06-19 | E-GEOD-2110 | biostudies-arrayexpress
Project description:Both developmental nutrition and adult nutrition affect life-history traits; however, little is known about whether the effect of developmental nutrition depends on the adult environment experienced. We used the fruit fly to determine whether life-history traits, particularly life span and fecundity, are affected by developmental nutrition, and whether this depends on the extent to which the adult environment allows females to realize their full reproductive potential. We raised flies on three different developmental food levels containing increasing amounts of yeast and sugar: poor, control, and rich. We found that development on poor or rich larval food resulted in several life-history phenotypes indicative of suboptimal conditions, including increased developmental time, and, for poor food, decreased adult weight. However, development on poor larval food actually increased adult virgin life span. In addition, we manipulated the reproductive potential of the adult environment by adding yeast or yeast and a male. This manipulation interacted with larval food to determine adult fecundity. Specifically, under two adult conditions, flies raised on poor larval food had higher reproduction at certain ages - when singly mated this occurred early in life and when continuously mated with yeast this occurred during midlife. We show that poor larval food is not necessarily detrimental to key adult life-history traits, but does exert an adult environment-dependent effect, especially by affecting virgin life span and altering adult patterns of reproductive investment. Our findings are relevant because (1) they may explain differences between published studies on nutritional effects on life-history traits; (2) they indicate that optimal nutritional conditions are likely to be different for larvae and adults, potentially reflecting evolutionary history; and (3) they urge for the incorporation of developmental nutritional conditions into the central life-history concept of resource acquisition and allocation.
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