Doctoral Dissertations

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Public Health

Major Professor

Jennifer M. Jabson Tree

Committee Members

Kristina Kintziger, Jiangang Chen, Julia Jaekel


Given the nature of the wars in Iraq and Afghanistan, and the ever-growing number of military service members (SMs) and veterans exposed to military-related trauma, mental illnesses among SMs and their negative impacts continue to be a focal point. However, several studies found that the majority of SMs, even those returning from combat, do not suffer from mental health issues. Therefore, the current study sought to address this discrepancy between previous research and actual military mental health statistics. The purpose of the study was to identify factors that placed SMs both at risk for and protected against depressive symptoms in adulthood.

Complete data for 14,660 respondents, including 1,024 SMs, were drawn from the fourth wave of the ongoing National Longitudinal Study of Adolescent to Adult Health (Add Health). The primary independent variable was timing of military entry, and the dependent variable was depressive symptoms measured in adulthood. Background characteristics and military-related characteristics and exposures were included as potential confounders and effect modifiers.

Early entrants (SMs who entered the military before age 21) had significantly lower depressive symptom scores in adulthood than civilians, even after controlling for background characteristics (β = -0.54, p < 0.01). Furthermore, biological sex, race, SES indicators in childhood, and adolescent depressive symptom scores significantly influenced depressive symptom scores in adulthood. In the military-only sample, current military service was found to protect against depressive symptoms (β = -0.65, p < 0.05), while serving one to 36 months on active duty (AD) (β = 1.03, p < 0.05) and seeing an ally wounded, killed, or dead (β = 1.02, p < 0.05) placed SMs at an increased risk. Service in the Air Force and Navy, type of military service experience, and length of time served in a combat zone were all found to modify the relationship between timing of military entry and depressive symptoms in adulthood.

An individual’s unique background, as well as the heterogeneity in their military-experience, impacts their depressive symptoms in adulthood. Understanding what factors place individuals at risk for and protect against mental illness is crucial to clearly understanding the relationship between military service and mental health outcomes. It is imperative to determine what influences military mental health so that public health practitioners and military specialists can effectively target those most at risk.

Available for download on Saturday, May 15, 2027

Files over 3MB may be slow to open. For best results, right-click and select "save as..."