Dissertations, Theses, and Capstone Projects

Date of Degree

9-2026

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy

Program

Psychology

Advisor

Laura Reigada

Advisor

Nicholas Sibrava

Committee Members

Deborah Walder

Regina Miranda

Adriana Espinosa

Subject Categories

Clinical Psychology

Keywords

Depression, cognition, behavior, race, gender

Abstract

Major depressive disorder is prevalent, chronic, and heterogeneous, including cognitive- affective (e.g., maladaptive beliefs or thinking patterns and sad mood) and somatic (e.g., fatigue, appetite, or sleep changes) symptom domains. While depression domains have been long theorized, research examining psychological mechanisms underlying this distinction is limited. Preliminary research suggests cognitive-affective symptoms relate more strongly to cognitive mechanisms (cognitive bias, perseverative thought), somatic symptoms relate more strongly to behavioral mechanisms (behavioral inhibition/activation), and gender, race, and ethnicity moderate these relationships. This study examined whether cognitive-affective and somatic symptom domains differentially relate to cognitive and behavioral mechanisms, and whether these relationships are moderated by gender, race, and ethnicity, both cross-sectionally and prospectively (4-week follow up). Adult community and student participants (N = 433) completed online self-report measures of perseverative thought, cognitive bias (following a negative mood induction), behavioral inhibition/activation, and depressive symptoms. Associations between mechanisms and symptom domains were tested with bootstrapped ridge regression. Moderation by gender, race, and ethnicity was tested using ridge interaction and OLS moderation. Cognitive and behavioral mechanisms were associated with both symptom domains, with no evidence of domain-specific associations cross-sectionally or prospectively. Ridge regression interaction models showed no sociodemographic moderation; however, OLS moderation revealed unexpected racial and ethnic differences, with mechanism-domain associations generally stronger for White than Black individuals, and several reversed associations among Black, Latinx, and other racial/ethnic groups. These findings suggest cognitive and behavioral mechanisms may operate similarly across depressive symptom domains. However, racial and ethnic differences in mechanism-domain associations raise concerns about the equivalence of questionnaires validated in predominantly White samples and may support culturally specific assessment and treatment. Future research should extend these preliminary findings using clinical, more diverse, and larger samples with improved symptom measurement.

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