Hippocampal Volume, PTSD, and Alcoholism in Combat Veterans

Abstract

Studies imposing rigorous control over lifetime alcohol intake have usually not found smaller hippocampal volumes in persons with posttraumatic stress disorder. Because the majority of negative studies have used adolescent samples, it has been suggested that chronicity is a necessary condition for such findings. To test the hypothesis that a smaller hippocampus in PTSD is unrelated to comorbid alcoholism or to chronicity, this study estimated hippocampal volume in a relatively large group (N=99) of combat veterans in which PTSD, lifetime alcohol abuse/dependence, and Vietnam versus Gulf War service were crossed. In subjects with histories of alcoholism, unadjusted hippocampal volume was 9% smaller in persons with PTSD than in those without PTSD. In nonalcoholic subjects, the PTSD-related difference in hippocampal volume was 3%. The failure to observe a strong association between PTSD and hippocampal volume in nonalcoholic subjects was not ascribable to younger age, reduced PTSD chronicity, or lower PTSD symptom severity. The possibility that smaller hippocampal volume is limited to groups in which PTSD is compounded by comorbid alcoholism is not necessarily incompatible with results suggesting a smaller hippocampus is predispositional to PTSD. Further examination of the role of alcoholism and other comorbid conditions in studies of brain structure and function in PTSD appears warranted.

Effects of traumatic brain injury and posttraumatic stress disorder on development of Alzheimer's disease in Vietnam Veterans using the Alzheimer's Disease Neuroimaging Initiative: Preliminary report

“…Hippocampal atrophy has been associated with PTSD in some studies [66, 97-99], but not others [100-103]. Hippocampal atrophy is typically found in AD dementia, but is not specific for this condition [104].…”

Altered inflammatory activity associated with reduced hippocampal volume and more severe posttraumatic stress symptoms in Gulf War veterans

“…Numerous structural magnetic resonance imaging (MRI) studies have reported reduced hippocampal volume in patients with PTSD relative to controls (Bremner et al, 1995; Vermetten, Vythilingam, Southwick, Charney, & Bremner, 2003; Wang et al, 2010; Woodward et al, 2006), and in individuals exposed to trauma who do not develop PTSD (Karl et al, 2006; Vythilingam et al, 2002). However, effect sizes are generally small and not all studies have replicated the effect of reduced hippocampal volume in PTSD (Mohlenhoff, Chao, Buckley, Weiner, & Neylan, 2014; Schuff et al, 2001).…”

Smaller Hippocampal Volume in Posttraumatic Stress Disorder: A Multisite ENIGMA-PGC Study: Subcortical Volumetry Results From Posttraumatic Stress Disorder Consortia

“…In addition to the main analysis of PTSD diagnosis, we performed separate analyses examining variables that have been hypothesized to influence the relationship between PTSD and subcortical volume, including gender effects (25), civilian versus military samples, childhood trauma (37), and alcohol use disorder (AUD) (38). …”