Effect of the APOE ε4 allele and combat exposure on PTSD among Iraq/Afghanistan-era veterans

Nathan A. Kimbrel, Michael A. Hauser, Melanie Garrett, Allison Ashley-Koch, Yutao Liu, Michelle F. Dennis, Rebecca C. Klein, Jean C. Beckham

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)307-315
Number of pages9
JournalDepression and Anxiety
Issue number5
StatePublished - May 1 2015
Externally publishedYes


  • APOE
  • PTSD
  • comorbidity
  • depression
  • genetic
  • veteran

ASJC Scopus subject areas

  • Clinical Psychology
  • Psychiatry and Mental health


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