In a series of cross-sectional studies analyzing the non-motor behaviors of adult and aged, male and female GPR37 KO mice and their wild-type littermates, it was found that aged GPR37 KO female mice exhibited mild improvements in olfactory function, whereas anxiety- and depression-like behaviors appeared to be significantly increased, demonstrating that deletion of the GPR37 receptor may exert neuroprotective effects in an age- and sex-dependent manner. The gene discussed is GPR37; the disease is major depressive disorder.