Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2015 May;32(5):307-15.
doi: 10.1002/da.22348. Epub 2015 Feb 24.

EFFECT OF THE APOE ε4 ALLELE AND COMBAT EXPOSURE ON PTSD AMONG IRAQ/AFGHANISTAN-ERA VETERANS

Nathan A Kimbrel  1 , Michael A Hauser, Melanie Garrett, Allison Ashley-Koch, Yutao Liu, Michelle F Dennis, Rebecca C Klein; Veterans Affairs Mid-Atlantic Mental Illness Research, Education, and Clinical Center Workgroup; Jean C Beckham
Collaborators, Affiliations

EFFECT OF THE APOE ε4 ALLELE AND COMBAT EXPOSURE ON PTSD AMONG IRAQ/AFGHANISTAN-ERA VETERANS

Nathan A Kimbrel et al. Depress Anxiety. 2015 May.

Abstract

Background: The apolipoprotein E (APOE) ε4 allele has been implicated in a range of neuropsychiatric conditions. The present research examined if the ε4 allele of the APOE gene moderated the effect of combat exposure on posttraumatic stress disorder (PTSD) among Iraq/Afghanistan-era veterans.

Method: Participants included 765 non-Hispanic White (NHW) and 859 non-Hispanic Black (NHB) Iraq/Afghanistan-era veterans. A structured interview established psychiatric diagnoses. Combat exposure and PTSD symptom severity were assessed via self-report.

Results: The most common lifetime diagnoses were depression (39.2%), PTSD (38.4%), and alcohol dependence (24.38%). After correcting for multiple comparisons, no significant effects were observed on any of the outcomes among the NHW sample; however, within the NHB sample, significant gene × environment (G × E) interactions were observed for lifetime PTSD (P = .0029) and PTSD symptom severity (P = .0009). In each case, the APOE ε4 allele had no effect on the outcomes when combat exposure was low; however, when combat exposure was high, an additive effect was observed such that ε4 homozygotes exposed to high levels of combat reported the highest rates of PTSD (92%) and the worst symptom severity scores on the Davidson Trauma Scale (M = 79.5).

Conclusions: Although preliminary, these findings suggest that the APOE ε4 allele, in conjunction with exposure to high levels of combat exposure, may increase veterans' risk for developing PTSD.

Keywords: APOE; PTSD; comorbidity; depression; genetic; veteran.

PubMed Disclaimer

Conflict of interest statement

The authors have no conflicts of interest to declare.

Figures

Figure 1
Figure 1
Plot of the APOE x combat exposure interaction on lifetime PTSD diagnosis (p = .0029) among the non-Hispanic Black (NHB) sample (n = 859). For each additional ε4 allele, the odds of having lifetime PTSD increased by 1.61, but only among those with high combat exposure (p = 0.0077).
Figure 2
Figure 2
Plot of the APOE x combat exposure interaction on PTSD symptom severity (p = 0.0009) among the non-Hispanic Black (NHB) sample (n = 859). As the number of ε4 alleles increased, the mean severity score on the Davidson Trauma Scale increased by 10.25 points, but only among those with high combat exposure (p = 0.0011).
Figure 3
Figure 3
Plot of the APOE x combat exposure interaction effect on lifetime psychiatric comorbidity (p = 0.0065) among the non-Hispanic Black (NHB) sample (n = 859). For each additional ε4 allele, the odds of having a greater number of lifetime psychiatric disorders increases by 1.55, but only among those with high combat exposure (p = 0.0053).
See this image and copyright information in PMC

References

    1. Hoge CW, Castro CA, Messer SC, et al. Combat duty in Iraq and Afghanistan, mental health care problems, and barriers to care. N Engl J Med. 2004;351:13–22. - PubMed
    1. Lapierre CB, Schwegler AF, Labauve BJ. Posttraumatic stress and depression symptoms in soldiers returning from combat operations in Iraq and Afghanistan. J Trauma Stress. 2007;20(6):933–943. - PubMed
    1. Elbogen EB, Wagner HR, Johnson SC, et al. Are Iraq and Afghanistan veterans using mental health services? New data from a national random-sample survey. Psychiatr Serv. 2013;64(2):134–141. - PMC - PubMed
    1. Smith TC, Ryan MA, Wingard DL, et al. New onset and persistent symptoms of post-traumatic stress disorder self reported after deployment and combat exposures: Prospective population based US military cohort study. BMJ. 2008;336:366–371. - PMC - PubMed
    1. Morissette SB, Woodward M, Kimbrel NA, et al. Deployment-related TBI, persistent postconcussive symptoms, PTSD, and depression in OEF/OIF veterans. Rehabil Psychol. 2011;56(4):340–350. - PMC - PubMed

Publication types

MeSH terms

Substances