Introduction This study examines the reciprocal relationship between social support and depressive symptoms among military cadets in Taiwan, a population facing unique academic and military pressures. While emerging adults are prone to mental health challenges, they encounter additional stressors such as strict hierarchies and separation from family. Social support is known to be a protective factor, yet its long-term effects and bidirectional relationship with depression remain underexplored, particularly in collectivist military cultures where mental health may be stigmatised. Using a cross-lagged panel model with three waves of data, this study also explores whether this relationship varies by gender.

Methods A secondary analysis of longitudinal data was conducted from the “Career Development of Military Academy Students” project, which surveyed all Taiwanese military academy students from the 111th class across three waves (W1–W3). The final sample consisted of 898 students (73.2% male, average age=20.9) from six military academies. To analyse the bidirectional relationship between social support and depression, autoregressive cross-lagged panel analysis using structural equation modelling (SEM) was employed. Multigroup SEM was used to assess gender difference.

Results The cross-lagged panel model revealed reciprocal effects between social support and depression in the overall sample, evident only between W1 and W2. From W2 to W3, depression influenced perceived social support, with a stronger effect observed in males than females. These results underscore the unique dynamics of social support and depression in military contexts, particularly for females, where the relationship appears more complex.

Conclusions The findings highlight the need for both systemic support structures and individualised interventions in military settings, considering gender differences and the evolving nature of mental health challenges. By addressing these factors, military leaders and mental health professionals can better support cadets in managing stress and depression, fostering a more resilient and mentally healthy military community.