Date of Award

Spring 5-31-2019

Document Type


Degree Name

Doctor of Philosophy in Clinical Psychology (PhD)


Clinical Psychology

First Advisor/Committee Member

Lynette H. Bikos

Second Advisor/Committee Member

David G. Stewart

Third Advisor/Committee Member

Kate Comtois

Fourth Advisor/Committee Member

Keyne Law


Adolescent Posttraumatic Stress Disorder (PTSD) is a multifaceted, debilitating disorder that if left untreated has been shown to lead to problematic internalizing and externalizing behaviors including suicidal ideation and substance use. Little is known about the course of PTSD in adolescents and less is known about the individual effects of PTSD symptom clusters. Furthermore, there is a dearth in the literature studying the predictive effects of PTSD, substance use and suicidality in adolescent samples. Participants were a clinical sample of adolescents referred from inpatient and outpatient clinics in the Pacific Northwest as part of a larger study. Ages of participants ranged from 13 to 19 (M=15.70) and were primarily white and female. This sample reported high rates of trauma exposure (M = 3.4) and subclinical but prevalent PTSD symptoms. Additionally, substance use was uncommon but moderately severe and prevalent but infrequent suicidal ideation (M = 7.06). We investigated the indirect effect of substance use on the relationship between the four symptom clusters of PTSD and suicidal ideation in this correlational study. We found significant correlations between trauma exposure and substance use (r(75) = .239, p ≤ .05), PTSD symptom clusters and suicidal ideation (Intrusion r(75) = .431, p ≤ .01; Avoidance r(75) = .324, p ≤ .01; NACM r(75) = .423, p ≤ .01; Arousal r(75) = .429, p ≤ .05). We did not find support that the four symptom clusters individually predicted suicidal ideation in regression analyses. Ancillary analysis results showed that total PTSD symptoms were predictive of suicidal ideation (b = .48, t(75) = 4.43, p = <.01). However, substance use did not mediate the relationship in any model. This study suggests that subclinical levels of cluster symptoms of PTSD is not predictive of suicidal ideation in adolescents and moreover substance use may not mediate the relationship. Total PTSD symptoms and trauma exposure were predictive of suicidal ideation and substance use respectively, suggesting that clinicians should assess and treat substance use and suicidal ideation when working with trauma exposed youth. Future investigation should focus on larger samples of non-clinical adolescents and use longitudinal measurements to make causal inferences.