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Unit cohesion during deployment and post-deployment mental health: is cohesion an individual- or unit-level buffer for combat-exposed soldiers?

  • Laura Campbell-Sills (a1), Patrick J. Flynn (a2), Karmel W. Choi (a3) (a4) (a5) (a6), Tsz Hin H. Ng (a7) (a8), Pablo A. Aliaga (a7) (a8), Catherine Broshek (a7) (a8), Sonia Jain (a9), Ronald C. Kessler (a10), Murray B. Stein (a1) (a9) (a11), Robert J. Ursano (a7) and Paul D. Bliese (a12)...



Unit cohesion may protect service member mental health by mitigating effects of combat exposure; however, questions remain about the origins of potential stress-buffering effects. We examined buffering effects associated with two forms of unit cohesion (peer-oriented horizontal cohesion and subordinate-leader vertical cohesion) defined as either individual-level or aggregated unit-level variables.


Longitudinal survey data from US Army soldiers who deployed to Afghanistan in 2012 were analyzed using mixed-effects regression. Models evaluated individual- and unit-level interaction effects of combat exposure and cohesion during deployment on symptoms of post-traumatic stress disorder (PTSD), depression, and suicidal ideation reported at 3 months post-deployment (model n's = 6684 to 6826). Given the small effective sample size (k = 89), the significance of unit-level interactions was evaluated at a 90% confidence level.


At the individual-level, buffering effects of horizontal cohesion were found for PTSD symptoms [B = −0.11, 95% CI (−0.18 to −0.04), p < 0.01] and depressive symptoms [B = −0.06, 95% CI (−0.10 to −0.01), p < 0.05]; while a buffering effect of vertical cohesion was observed for PTSD symptoms only [B = −0.03, 95% CI (−0.06 to −0.0001), p < 0.05]. At the unit-level, buffering effects of horizontal (but not vertical) cohesion were observed for PTSD symptoms [B = −0.91, 90% CI (−1.70 to −0.11), p = 0.06], depressive symptoms [B = −0.83, 90% CI (−1.24 to −0.41), p < 0.01], and suicidal ideation [B = −0.32, 90% CI (−0.62 to −0.01), p = 0.08].


Policies and interventions that enhance horizontal cohesion may protect combat-exposed units against post-deployment mental health problems. Efforts to support individual soldiers who report low levels of horizontal or vertical cohesion may also yield mental health benefits.


Corresponding author

Author for correspondence: Laura Campbell-Sills, E-mail:


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Unit cohesion during deployment and post-deployment mental health: is cohesion an individual- or unit-level buffer for combat-exposed soldiers?

  • Laura Campbell-Sills (a1), Patrick J. Flynn (a2), Karmel W. Choi (a3) (a4) (a5) (a6), Tsz Hin H. Ng (a7) (a8), Pablo A. Aliaga (a7) (a8), Catherine Broshek (a7) (a8), Sonia Jain (a9), Ronald C. Kessler (a10), Murray B. Stein (a1) (a9) (a11), Robert J. Ursano (a7) and Paul D. Bliese (a12)...


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