PTSD, depression, and their comorbidity in relation to suicidality: cross-sectional and prospective analyses of a national probability sample of women.

Background: A growing body of literature implicates major depressive disorder (MDD) and posttraumatic stress disorder (PTSD) as risk factors for suicidal ideation (SI) and suicide attempts (SA), though research has not adequately examined their differential contributions to increasing suicide risk prospectively or cross-sectionally.
Methods: The contribution of these disorders and their comorbidity to SI and SA was examined using a national household probability sample of women (N=3,085) and covarying for trauma history, substance abuse, and demographic variables.
Results: Cross-sectional analyses indicated that lifetime comorbidity of MDD and PTSD were associated with much higher prevalence of SI than either diagnosis alone; prevalence of SI was elevated and comparable for PTSD and MDD only. Comorbid diagnosis and PTSD only groups displayed greater prevalence of SA than those with MDD only. Lastly, a 2-year prospective analysis indicated that PTSD only at baseline was predictive of greater subsequent SI risk than MDD only, though comorbid diagnosis did not differ from either PTSD only or MDD only.
Conclusions: PTSD appears to be a particularly strong predictor of SI and SA. Overall, only 16% of women with lifetime SA did not have a history of MDD or PTSD, highlighting the importance of assessing these variables when assessing suicide risk.