CASP9 and post-traumatic stress disorder: In Past PTSD > 5 y, the negative correlation between CASP-9 and Problem-Focused Coping (Rho = −0.29; Figure 4A) demonstrates that despite decreasing CASP-9 levels (2.0–26.91 ng/mL), active coping remains impaired, possibly reflecting learned helplessness or persistent negative alterations in cognition (Criterion D).