GAD1 and post-traumatic stress disorder: Beard and Björgvinsson (2014) examined the factor structure of the GAD-7 using heterogeneous psychiatric samples (i.e., each AD, MDD, bipolar disorder, and borderline personality disorder) and showed that a two-dimensional factor model provided the best fit for each AD (GAD, PTSD, SAD, and PD). However, given that Kroenke et al. (2007) showed that participants with each type of AD had moderate levels of depressive and somatic symptoms, it is necessary to know whether the GAD-7 has the same factor structure in these various populations.