Early Event-Related Potential Changes During Working Memory Activation Predict Rapid Decline in Mild Cognitive Impairment

Background. The conversion of mild cognitive impairment (MCI) to Alzheimer's disease is associated with substantial compromise of neocortical circuits subserving rapid cognitive functions such as working memory. Event-related potential (ERP) analysis is a powerful tool to identify early impairment of these circuits, yet research for an electrophysiological marker of cognitive deterioration in MCI is scarce. Using a "2-back” activation paradigm, we recently described an electrophysiological correlate of working memory activation (positive-negative working memory [PNwm] component) over parietal electrodes. Methods. Ours was a longitudinal study of 24 MCI patients with ERP analysis at inclusion and neuropsychological follow-up after 1 year. We used ERP waveform subtraction analysis between the n-back and control tasks. Analysis of variance (ANOVA) was used to compare electroencephalograph latencies between progressive MCI (PMCI) and stable MCI (SMCI), and univariate regression was used to assess the relationship between neuropsychological measures at baseline and clinical outcome. Results. Thirteen (54%) MCI patients showed PMCI, and 11 (46%) remained stable (SMCI). In SMCI, a PNwm component with significantly larger density compared to baseline was identified when subtracting the detection task for both the 1- and 2-back tasks. In contrast, in PMCI, the PNwm component was absent in both 1-back and 2-back conditions. Neuropsychological variables and n-back test performance at inclusion did not predict cognitive deterioration 1 year later. Conclusions. In conjunction with recent functional imaging data, the present results support the notion of an early dysfunction of neural generators within the parietal cortex in MCI. They also reveal that the absence of the PNwm component may provide an easily applicable qualitative predictive marker of rapid cognitive deterioration in MC

Tempo and its Tribulations

Bongaarts and Feeney offer alternatives to period life expectancy with a set of demographic measures equivalent to each other under a Proportionality Assumption. Under this assumption, we show that the measures are given by exponentially weighted moving averages of earlier values of period life expectancy. They are indices of mortality conditions in the recent past. The period life expectancy is an index of current mortality conditions. The difference is a difference between past and present, not a ``tempo distortion'' in the present. In contrast, the Bongaarts-Feeney tempo-adjusted Total Fertility Rate is a measure of current fertility conditions, which can be understood in terms of a process of birth-age standardization.demographic translation, life expectancy, standardization, tempo, TFR

Individual fecundity dynamically predicts remaining life expectancy in medflies

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Old age mortality : a state of the art

This Phd research report aims to obtain a better understanding of the recent changes in mortality of the elderly population in developed countries. It's essence will be a critical thinking, without performing empirical work, which means that the analysis and concepts of the actual demographic literature will form the main body of this work. There are two central questions: Which age and cause specific mortality trends caused these recent changes in the life expectancy?Did the increase in life expectancy of the elderly population accelerate, continue or decline in recent years?"Aquesta memòria de recerca de doctorat té com a objectiu obtenir una millor comprensió dels recents canvis de mortalitat de la població més vella en els països desenvolupats. L'essència d'aquest treball és més bé teòric que empíric, per tant l'anàlisis i conceptes de la recent literatura demogràfica formaran el cos principal d'aquest treball. Hi ha dues qüestions principals: Quines edats i causes de mort provoquen aquests canvis recents de l'esperança de vida ? L 'augment de l' esperança de vida de la població més vella s' accelera, accelerar, es manté o disminueixr en aquests darrers anys

Redistribution and Insurance: Mandatory Annuitization with Mortality Heterogeneity

This paper examines the distributional implications of mandatory longevity insurance when there is mortality heterogeneity in the population. Previous research has demonstrated the significant financial redistribution that occurs under alternative annuity programs in the presence of differential mortality across groups. This paper embeds that analysis into a life cycle framework that allows for an examination of distributional effects on a utility-adjusted basis. It finds that the degree of redistribution that occurs from the introduction of a mandatory annuity program is substantially lower on a utility-adjusted basis than when evaluated on a purely financial basis. In a simple life-cycle model with no bequests, complete annuitization is welfare enhancing even for those individuals with much higher-than-average expected mortality rates, so long as administrative costs are sufficiently low. These findings have implications for policy toward annuitization, particularly as part of a reformed Social Security system.