The Effect of Alzheimer’s Disease-Associated Genetic Variants on Longevity

Human longevity is influenced by the genetic risk of age-related diseases. As Alzheimer’s disease (AD) represents a common condition at old age, an interplay between genetic factors affecting AD and longevity is expected. We explored this interplay by studying the prevalence of AD-associated single-nucleotide-polymorphisms (SNPs) in cognitively healthy centenarians, and replicated findings in a parental-longevity GWAS. We found that 28/38 SNPs that increased AD-risk also associated with lower odds of longevity. For each SNP, we express the imbalance between AD- and longevity-risk as an effect-size distribution. Based on these distributions, we grouped the SNPs in three groups: 17 SNPs increased AD-risk more than they decreased longevity-risk, and were enriched for β-amyloid metabolism and immune signaling; 11 variants reported a larger longevity-effect compared to their AD-effect, were enriched for endocytosis/immune-signaling, and were previously associated with other age-related diseases. Unexpectedly, 10 variants associated with an increased risk of AD and higher odds of longevity. Altogether, we show that different AD-associated SNPs have different effects on longevity, including SNPs that may confer general neuro-protective functions against AD and other age-related diseases.

Underestimating Lifespans? Why Longevity Risk Exists in Retirement Planning and Superannuation Policy

<p>The pace of increasing life expectancy in recent decades came as a surprise to demographers, as mortality rates unexpectedly improved at the oldest ages in developed countries. The most common policy response, although one not yet planned for New Zealand, is to increase eligibility age for the public pension. Given the complexity and uncertainty of processes driving mortality improvement, future lifespans cannot be known. However, it is questionable whether policy makers and individuals understand the extent of past and likely future lifespan increase. Available evidence suggests individuals tend to underestimate how long they may live. Population mortality forecasts are generally conservative and poorly explain longevity uncertainties. Longevity risk - the possibility that future lifespans will be longer than anticipated - threatens individuals' pre-retirement financial planning and public pension policy. This thesis examines the extent of longevity risk, its causes, significance and remedies, in these two domains, for New Zealand. The theoretical existence of longevity risk has been acknowledged, but has not been subject to critical analysis in New Zealand or elsewhere. Here, a unique generalisable methodology exploiting insights available from international mortality comparisons is designed, combining actuarial and demographic theory. After assessing the flaws in the time-dependent or period approach to measurement of life expectancy that are known in theory but underexplored in practice, the method emphasises the lifecourse or cohort approach. The three factors that determine longevity risk - plausible population lifespan prospects, the lifespan assumptions used by policy makers and individuals' subjective lifespan expectations - are identified and the relationships between them analysed for New Zealand. An interpretation of the consistency of New Zealand's past mortality trends and future projections with those of other British settler countries, supplemented by a review of the consequences of mortality variance within New Zealand, shows that plausible lifespans in New Zealand are likely to be higher than those in the official projections on which policy makers rely. The first survey to ask how long New Zealanders think they will live shows that collectively, New Zealanders are more likely to underestimate future lifespan than not, based on a variety of beliefs about mortality that are not consistent with the evidence on increasing lifespans. Longevity risk from underestimation of future lifespans is revealed in New Zealand policy making and in individual New Zealanders' retirement plans. The most likely cause is the repeated misuse of life expectancy indicators in an environment lacking public discourse about increasing longevity. A remedy would be switching from using flawed period life expectancy indicators to using cohort life expectancy or modal age at death. Using plausible estimates for future lifespans based on more optimistic estimates than the official projections most often referenced would be important but mitigate longevity risk to a lesser extent. A more extensive public debate than has been held so far about eligibility age for New Zealand's public pension would itself, if using appropriate indicators for future lifespans, provide an opportunity to address longevity risk.</p>

Underestimating Lifespans? Why Longevity Risk Exists in Retirement Planning and Superannuation Policy

<p>The pace of increasing life expectancy in recent decades came as a surprise to demographers, as mortality rates unexpectedly improved at the oldest ages in developed countries. The most common policy response, although one not yet planned for New Zealand, is to increase eligibility age for the public pension. Given the complexity and uncertainty of processes driving mortality improvement, future lifespans cannot be known. However, it is questionable whether policy makers and individuals understand the extent of past and likely future lifespan increase. Available evidence suggests individuals tend to underestimate how long they may live. Population mortality forecasts are generally conservative and poorly explain longevity uncertainties. Longevity risk - the possibility that future lifespans will be longer than anticipated - threatens individuals' pre-retirement financial planning and public pension policy. This thesis examines the extent of longevity risk, its causes, significance and remedies, in these two domains, for New Zealand. The theoretical existence of longevity risk has been acknowledged, but has not been subject to critical analysis in New Zealand or elsewhere. Here, a unique generalisable methodology exploiting insights available from international mortality comparisons is designed, combining actuarial and demographic theory. After assessing the flaws in the time-dependent or period approach to measurement of life expectancy that are known in theory but underexplored in practice, the method emphasises the lifecourse or cohort approach. The three factors that determine longevity risk - plausible population lifespan prospects, the lifespan assumptions used by policy makers and individuals' subjective lifespan expectations - are identified and the relationships between them analysed for New Zealand. An interpretation of the consistency of New Zealand's past mortality trends and future projections with those of other British settler countries, supplemented by a review of the consequences of mortality variance within New Zealand, shows that plausible lifespans in New Zealand are likely to be higher than those in the official projections on which policy makers rely. The first survey to ask how long New Zealanders think they will live shows that collectively, New Zealanders are more likely to underestimate future lifespan than not, based on a variety of beliefs about mortality that are not consistent with the evidence on increasing lifespans. Longevity risk from underestimation of future lifespans is revealed in New Zealand policy making and in individual New Zealanders' retirement plans. The most likely cause is the repeated misuse of life expectancy indicators in an environment lacking public discourse about increasing longevity. A remedy would be switching from using flawed period life expectancy indicators to using cohort life expectancy or modal age at death. Using plausible estimates for future lifespans based on more optimistic estimates than the official projections most often referenced would be important but mitigate longevity risk to a lesser extent. A more extensive public debate than has been held so far about eligibility age for New Zealand's public pension would itself, if using appropriate indicators for future lifespans, provide an opportunity to address longevity risk.</p>

Valuing Life as an Asset, as a Statistic, and at Gunpoint

Rationalizing the stark differences between the Human Capital (HK) and the Statistical Values (VSL) of a human life is complicated by the absence of common foundations. We solve a human capital investment model with longevity risk to characterize the HK. The associated indirect utility yields the willingness to pay (WTP) against mortality; the marginal WTP solves the VSL. Indifference between life and certain death characterizes the limiting WTP and provides a Gunpoint Value (GPV). A structural estimation reveals similar HK (300 K$) and GPV (251 K$) and explains a much larger VSL (4.98 M$) by a strongly concave WTP.

Is Longevity Acceleration Sustainable? An Entropy-Based Trial of the Population of Spain vs. Japan

Longevity risk is a major concern for governments around the world as they have to address social benefits, whether in the form of pensions, healthcare, or caring for dependents and providing long-term care, and so forth, which directly impact countries’ budgets. This paper uses a single entropy index to measure this type of risk. This methodology is clearly different from the one traditionally used in the literature, which is nearly entirely based on measuring the evolution of mathematical life expectancy. The authors used the longest-living populations in the world, Japan and Spain, to create a database in order to analyse the virtue of the indicator. The aim was to establish whether the longevity of those populations is accelerating or decelerating, compared by sex, and whether that occurs at the same intensity at different stages of a person’s life in each case. If the indicator showed differences in intensity, it would be a benchmark for the insurance and financial industry, providing it with information to market different products.