Defense Date


Document Type


Degree Name

Master of Science



First Advisor

Roseann E. Peterson, Ph.D.

Second Advisor

Amanda Elswick Gentry, Ph.D.

Third Advisor

LaMont Cannon, Ph.D.

Fourth Advisor

Allison Johnson, Ph.D.


Major depression is considered a complex trait influenced by both polygenic risk factors and environmental exposures, such as childhood trauma. This study applied statistical genetic methods to calculate aggregate genetic risk for major depression to predict depressive symptoms scores in a college student sample. Data were from the Spit for Science (S4S) study in which college students from a large urban university self-reported interpersonal trauma (IPT) exposure prior to college and depressive symptoms from the past month (N = 7502; ancestry group: 20% African [AFR], 12% Admixed Americas [AMR], 10% East Asian [EAS], 49% European [EUR], 8% South Asian [SAS]). Major depression-PRS were created using PRS-CSx with summary statistics from large-scale genome-wide association studies (GWAS) of major depression in EUR, AFR, and EAS ancestry cohorts. Mean depressive symptoms scores and rates of IPT exposure were statistically significantly higher in female participants (μscore = 9.50, prop.IPT = 0.42) than in males (μscore = 8.21, prop.IPT = 0.32, all �� < 0.001). In the phenotypic-only model, symptoms of depression were associated with IPT exposure (�� = 1.48, �� = 8.2110-22) and sex (�� = 1.05, �� = 4.3810-21), but there was no evidence of statistical interaction between them (�� = 0.218). In the fixed effects meta-analysis across ancestry groups, major depression-PRS were significantly associated with depressive symptoms (�� = 0.209, �� = 1.1410-4), accounting for a small proportion of the variance (R2 range: 0.0003 - 0.004). Sex (�� = 1.091, �� = 1.5910-22) and IPT exposure (�� = 1.320, �� = 4.5910-5) were strongly associated with depressive symptoms, but statistical interactions between major depression-PRS and IPT exposure were not found (�� = 0.251). When inspecting results by ancestry groups, major depression-PRS were only statistically significant with depressive symptoms scores in the European (�� = 0.277, �� = 3.9110-4) and Admixed Americas (�� = 0.454, �� = 6.1010-3) ancestry groups. In every model, biological sex and IPT exposure had significant main effects on depressive symptoms scores. Further study is needed as more large-scale GWAS become available to increase the predictive ability of PRS across the ancestry spectrum in the pursuit of health equity in precision psychiatry.


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