To illustrate the differences in total negative affectivity between groups, mean stacked symptom severity scores on the STAI (trait), BDI, and ASI for nonexposed and trauma-exposed control groups and single-trauma and multiple-trauma PTSD groups are illustrated in the bottom panel. In the top panel, mean duration of PTSD (i.e., disorder chronicity) in years for single-trauma and multiple-trauma PTSD groups are plotted, showing that broad negative affectivity and chronicity demonstrate concurrent increases. ASI, Anxiety Sensitivity Index; BDI, Beck Depression Inventory; PTSD, post-traumatic stress disorder; STAI, State Trait Anxiety Inventory.