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

Laura Campbell-Sills; Patrick J Flynn; Karmel W Choi; Tsz Hin H Ng; Pablo A Aliaga; Catherine Broshek; Sonia Jain; Ronald C Kessler; Murray B Stein; Robert J Ursano; Paul D Bliese

doi:10.1017/S0033291720001786

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

Psychol Med. 2022 Jan;52(1):121-131. doi: 10.1017/S0033291720001786. Epub 2020 Jun 10.

Authors

Laura Campbell-Sills¹, Patrick J Flynn², Karmel W Choi^{3

4

5

6}, Tsz Hin H Ng^{7

8}, Pablo A Aliaga^{7

8}, Catherine Broshek^{7

8}, Sonia Jain⁹, Ronald C Kessler¹⁰, Murray B Stein^{1

9

11}, Robert J Ursano⁷, Paul D Bliese¹²

Affiliations

¹ Department of Psychiatry, University of California San Diego, La Jolla, CA, USA.
² Department of Management, Innovation, and Entrepreneurship, Poole College of Management, North Carolina State University, Raleigh, NC, USA.
³ Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA.
⁴ Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
⁵ Psychiatric and Neurodevelopmental Genetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.
⁶ Stanley Center for Psychiatric Research, Broad Institute, Boston, MA, USA.
⁷ Department of Psychiatry, Center for the Study of Traumatic Stress, Uniformed Services University of the Health Sciences, Bethesda, MD, USA.
⁸ Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA.
⁹ Department of Family Medicine and Public Health, University of California San Diego, La Jolla, CA, USA.
¹⁰ Department of Health Care Policy, Harvard Medical School, Boston, MA, USA.
¹¹ VA San Diego Healthcare System, San Diego, CA, USA.
¹² Department of Management, Darla Moore School of Business, University of South Carolina, Columbia, SC, USA.

Abstract

Background: 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.

Methods: 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.

Results: 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].

Conclusions: 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.

Keywords: Depression; military personnel; multilevel analysis; post-traumatic stress disorder; protective factors; psychological resilience; risk factors; suicidal ideation.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, N.I.H., Extramural

MeSH terms

Afghan Campaign 2001-
Humans
Mental Health
Military Personnel* / psychology
Risk Factors
Stress Disorders, Post-Traumatic* / psychology
Suicidal Ideation

Grants and funding

U01 MH087981/MH/NIMH NIH HHS/United States