APPROVAL SHEET Title of Thesis: “Changes in Cognitive-Behavioral Constructs Across Treatment Modalities for Seasonal Affective Disorder: Cognitive-Behavioral Therapy, Light Therapy, and their Combination” Name of Candidate:

Title of Thesis: Changes in Cognitive-Behavioral Constructs Across Treatment Modalities for Seasonal Affective Disorder: Cognitive-Behavioral Therapy, Light Therapy, and Their Combination Kathryn Tierney Lindsey, Master of Science, 2003 Thesis directed by: Kelly J. Rohan, Ph.D. Assistant Professor Department of Medical and Clinical Psychology Changes in cognitive and behavioral factors have been examined as potential mechanisms of change behind depression’s therapeutic response. This study examines cognitive-behavioral factor change across treatments for seasonal affective disorder (SAD). Participants diagnosed with Major Depression, Recurrent, with Seasonal Pattern and a current SAD episode (N = 35) were randomly assigned to light therapy (LT), group cognitive-behavioral therapy (CBT), or a combination treatment (CBT+LT). Participants completed the Automatic Thoughts Questionnaire, Dysfunctional Attitudes Scale, Response Styles Questionnaire, and the Pleasant Events Schedule at preand posttreatment. Regardless of treatment group, participants’ negative automatic thoughts and dysfunctional attitudes improved across treatment, and rumination trended toward improvement. Pleasant event frequency, enjoyment, and derived reinforcement did not change for any group across treatment. Initial dysfunctional attitudes levels did not predict post-treatment depressive symptoms or remission rates. Although differential mechanisms of change between groups were not revealed, cognitive processes appear to change over SAD treatment.