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

• Published in: Depression and anxiety Vol. 32; no. 5; pp. 307 - 315
• Main Authors: Kimbrel, Nathan A., Hauser, Michael A., Garrett, Melanie, Ashley-Koch, Allison, Liu, Yutao, Dennis, Michelle F., Klein, Rebecca C., Beckham, Jean C.
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.05.2015
• Subjects: Afghan Campaign 2001; African Americans - genetics; African Americans - psychology; African Americans - statistics & numerical data; Alleles; APOE; Apolipoprotein E4 - genetics; comorbidity; depression; European Continental Ancestry Group - genetics; European Continental Ancestry Group - psychology; European Continental Ancestry Group - statistics & numerical data; Female; Gene-Environment Interaction; genetic; Humans; Iraq War, 2003-2011; Male; PTSD; Self Report; Stress Disorders, Post-Traumatic - genetics; Stress Disorders, Post-Traumatic - psychology; veteran; Veterans - psychology; Veterans - statistics & numerical data; Warfare; PTSD; genetic; comorbidity; APOE; depression; veteran
• ISSN: 1091-4269; 1520-6394
• DOI: 10.1002/da.22348

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.