Alzheimer's disease (AD) is characterized by the accumulation of amyloid β (Aβ) plaques in the brain, leading to cognitive impairment and other clinical symptoms. The 5XFAD mouse model is commonly used in AD research because it expresses five human transgenes that result in the accumulation of Aβ plaques and cognitive decline at a relatively early age. Behavioral experiments are frequently conducted using this model; however, the effect size has not yet been reported. In this study, we examined basic cognition and locomotion in 5XFAD mice with a C57BL6/J background (5XFAD-J) at 6 months of age, a period in which impairments of cognitive function and locomotion are commonly observed. We analyzed the effect sizes of cognitive and locomotive experiments in the 5XFAD mice compared with those in the wild-type mice. Our results suggest that for long-term memory analysis, the novel object recognition test (p = 0.013, effect size 1.24) required a sample size of at least 12 to obtain meaningful results. Moreover, analysis of general locomotion over total distance with the Laboratory Animal Behavior Observation, Registration and Analysis System (LABORAS) test during the dark phase (p = 0.007, effect size -1.37) needed a sample size of 10 for a statistical power (1-β) of 0.8. In conclusion, we can conduct more ethical and scientifically rigorous animal experiments using 5XFAD mice based on the effect and sample sizes suggested in this study.
Keywords: 5XFAD-J; Alzheimer’s disease; LABORAS; behavior; novel object recognition test; sample size.