The TAR DNA-binding protein 43 (TDP-43) pathology characterizes the disease spectrum of amyotrophic lateral sclerosis–frontotemporal dementia (ALS-FTD). TDP-43 studies have used mouse models to assess behavioral, motor, and cognitive symptoms. Our study investigates the relationship between mouse behavior and the wild-type (WT) and TDP-43 mutated genotypes. Generally, study results are analyzed using analysis of variance (ANOVA) methods. However, common ANOVA methods are limited in their ability to capture complex relationships within the data. We propose a multivariate hierarchical Bayesian regression model with cyclic splines to model the relationship between behavioral time and genotype. Posterior predictive checks show that our proposed Bayesian model is able to describe the data accurately, unlike common ANOVA methods.