CRHR2 and Anxiety: However, the mice in this study are the same strain as reported with increased anxiety by Bale et al.[50] and an anxious phenotype was described for both group- [50] and singly [51] housed CRFR2-null mice from 9 [40] to 24 [50] weeks of age, but not at 16 weeks [62], meaning that these factors are unlikely to explain the inconsistency.