*3.1. Survival*

Survival, from birth to 16 months of age, of an initial sample of fifty-nine mice (29 NTg, 17 males, 12 females; 30 3xTg-AD, 16 males; 14 females) is illustrated in Figure 1A. Log-rank analyses show an overall difference in survival curves over the four groups (χ2(3) = 10.634, *p* = 0.014). There was no significant difference between the curves for NTg male and female mice, but female 3xTg-AD mice had a shorter lifespan than male 3xTg-AD mice (χ2(1) = 5.168, *p* = 0.023). Pairwise comparisons in the survival curve confirmed the effect of sex factor with females' worse survival, independently of the genotype (χ2(1) = 8.224, *p* = 0.004). Both groups of females exhibited an early 10% mortality rate before young adulthood (2 months of age), and their mean life expectancy was achieved at late adulthood (459 days or 15.1 months in NTg females, 493 days or 16.2 months in 3xTg-AD females). However, they differed in the temporal course of mortality, with a young adulthood and late adulthood mortality pattern in NTg and 3xTg-AD mice, respectively. In this cohort, the drop of survival for male NTg mice was at middle age (12 months), and at the end of the experiment (16 months), their survival rate was 62%. In contrast, the survival of male 3xTg-AD mice was 92%. Rates of censored data for each group ranged from 93.8 to 50%. Thirty-six animals started the experimental design, 17 NTg (10 males, seven females) mice, and 19 3xTg-AD (10 males, nine females). During the experimental research, three NTg males, two NTg females, and four 3xTg-AD females died.

## *3.2. HPA Axis Endocrine Status*

A sex effect was observed with increased levels of corticosterone in the plasma of females (Sex (S), Factorial analysis (F) (1,27) = 30.015, *p <* 0.001) as compared to respective male counterparts (post hoc test, *p <* 0.006). This effect was more notorious in the NTg groups, leading to an overall genotype difference as well (Figure 1B) (G, F (1,27) = 4.634, *p* = 0.042).

**Figure 1.** Survival, hypothalamic–pituitary–adrenal (HPA) axis endocrine status and physical health. (**A**) Survival; (**B**) corticosterone levels; physical health: (**C**) body weight, and (**D**) frailty scores of 14-month-old mice. Results are expressed as the mean ± SEM. Initial sample size: NTg, male *n* = 10, female *n* = 7; 3xTg-AD, male *n* = 10, female *n* = 9. Bars illustrate the genotype groups, as indicated in the abscissae. Symbols are used to illustrate individual values of males (black, left panel) and females (red, right panel). In green: the no-survivors. Statistics: 2 × 2 factorial ANOVA analysis design: genotype (G), sex (S) and genotype × sex (G×S) interaction effects, \* *p* < 0.05, \*\* *p* < 0.01, \*\*\* *p* < 0.001 (above line). Student *t*-test comparisons: \* *p* < 0.05, \*\* *p* < 0.01, \*\*\* *p* < 0.001 vs. the corresponding NTg group; ## *p* < 0.01, ### *p* < 0.001 vs. the corresponding male group.
