*2.4. Body Weight, Mouse Clinical Frailty Index Assessment, and Survival*

After the behavioral assessment, the body weight was recorded. Frailty was assessed using an adaptation of the MCFI [31], including 30 "clinically" assessed non-invasive items. For 29 of these items, mice were given a score 0 if not presented, 0.5 if there was a mild deficit, and 1 for severe deficit. Weight was scored based on the number of standard deviations from a reference mean. The clinical evaluation included the integument, the physical/musculoskeletal system, the vestibulocochlear/auditory systems, the ocular and nasal systems, the digestive system, the urogenital system, the respiratory system, signs of discomfort, and body weight. Survival was recorded continuously with a daily cadence.
