Electronic Thesis and Dissertation Repository


Doctor of Philosophy




Dr. David Dozois


Major Depression and anxiety disorders are prevalent, costly, and comorbid disorders. These emotional disorders also share some vulnerability factors, making them good candidates for transdiagnostic or simultaneous prevention. The current study is a double-blind, primary prevention study that focuses on preventing emotional disorders in at risk, first and second year undergraduate students. Three internet-delivered preventative programs were compared: a Cognitive Behavioural Therapy (CBT) intervention (MoodGYM), an attentional bias modification program (Dandeneau & Baldwin, 2004), and an active attentional control. Participants (n = 354) completed symptom measurement pre- and post- a six-week intervention and again at a four-month follow-up, when they were also administered a structured diagnostic interview. Participants in the CBT condition showed more rapid and continuous depressive symptom improvement between baseline and follow-up than did participants in the other two conditions. In addition, significantly fewer individuals in the CBT condition met diagnostic criteria for Major Depression at follow-up than in the other conditions. By contrast, anxiety all groups demonstrated a similar and significant level of improvement over time. No significant differences were found in the frequency of anxiety disorders across conditions. Additionally, the attentional training and control conditions performed identically, consistent with recent research on internet-delivered attentional training. These results demonstrate the clear benefit of MoodGYM for reducing the symptom severity and frequency of depression, and suggest this intervention may also hold some benefit for reducing anxiety symptoms. These results are discussed in the context of future prevention research and implementation.