Long-term trajectories of depressive symptoms by military affiliation.

Objectives: Using a national sample of Americans, this study estimated and compared patterns of depressive symptom trajectories stratified by military service. This study then examined associations between sociodemographic factors theorized to shape entry into military service and trajectory patterns.

Method: Data came from the National Longitudinal Study of Adolescent to Adult Health, a nationally representative study that followed participants from adolescence (1994-1995) through midlife (2016-2018). Latent growth mixture modeling was used to estimate depressive symptom trajectories among civilians ( = 17,644) and participants who served in the military ( = 1266). Associations between trajectory membership and sociodemographic factors were tested with multinomial regression.

Results: Trajectories were best represented by 4-class linear models. "Low" was the largest class, representing 74.4% of civilians and 70.4% of those who served. The second largest class, "low then increasing," was comprised of 13.6% of civilians and 19.6% of service members. The third smallest class, "high then decreasing" class, included 8.8% of civilians and 4.5% of service members. An "increasing" class emerged with high depressive symptoms by midlife, comprised of 3.2% of civilians and 5.5% of those who served. Gender and family structure had robust associations with trajectory membership.

Discussion: A larger percentage of those who served were in the "increasing" trajectory characterized by concerningly high depressive symptoms by midlife, underscoring the need for continued screening in depressive symptoms throughout the life course. Associations between family structure and gender on depressive symptoms support calls for conceptualizing family structure as a social determinant of health and continued investment in women's health.