The problem of genotype and sex differences in life expectancy in transgenic AD mice.

The lifespan of mice shows genotype, sex and laboratory effects, but little is known about genotype or sex differences in life expectancy of mouse models of Alzheimer's disease (AD). This paper examines the lifespan of males and females of different mouse models of AD and their wildtype strains. Genotype and sex dependent differences in longevity have important implications for designing experiments with Alzheimer's mouse models, comparing genotype and sex differences in aging mouse models, designing drug treatment regimes and the translation of mouse data to human clinical studies. We conclude that the concept of aging and age-related disorders in mice must be reconsidered based on genotype and sex differences in mouse life expectancy data. Use of concepts such as relative age, prospective lifespan and proportion of lifespan remaining should be included in studies of age-related changes in mouse brains and behavior. Finally, measures such as the Frailty Index, which is independent of chronological age might be used to determine a common scale of aging for all mouse strains.