This study used quantitative volumetric magnetic resonance imaging techniques to explore the neuroanatomic correlates of chronic, combat-related posttraumatic stress disorder (PTSD) in seven Vietnam veterans with PTSD compared with seven nonPTSD combat veterans and eight normal nonveterans. Both left and right hippocampi were significantly smaller in the PTSD subjects compared to the Combat Control and Normal subjects, even after adjusting for age, whole brain volume, and lifetime alcohol consumption. There were no statistically significant group differences in intracranial cavity, whole brain, ventricles, ventricle:brain ratio, or amygdala. Subarachnoidal cerebrospinal fluid was increased in both veteran groups. Our finding of decreased hippocampal volume in PTSD subjects is consistent with results of other investigations which utilized only trauma-unexposed control groups. Hippocampal volume was directly correlated with combat exposure, which suggests that traumatic stress may damage the hippocampus. Alternatively, smaller hippocampi volume may be a pre-existing risk factor for combat exposure and/or the development of PTSD upon combat exposure.

Declarative memory impairment is a frequent complaint of patients suffering from posttraumatic stress disorder (PTSD). We assessed memory, attention, visual spatial skills, and executive function in Vietnam combat veterans with (n = 19) and without (n = 13) PTSD. Although PTSD subjects demonstrated a "generalized impairment" relative to non-PTSD subjects on a majority of tasks, only attention and memory provided unique and independent prediction of PTSD versus non-PTSD status. Our findings suggest that memory functioning represents a neurocognitive domain of specific relevance to the development of PTSD in trauma-exposed individuals, which can be distinguished from generalized attentional impairment as well as the effects of trauma exposure severity, IQ, comorbid depression, history of alcohol use, and history of developmental learning problems.

Neuropsychological deficits have been reported among trauma survivors with posttraumatic stress disorder (PTSD). It is often assumed that these cognitive difficulties are toxic consequences of trauma exposure. Alternatively, they may reflect preexisting characteristics that contribute to the likelihood of developing PTSD. To address this possibility, the authors evaluated cognitive performance in monozygotic twin pairs who were discordant for combat exposure. Pairs were grouped according to whether the combat-exposed brother developed PTSD. The combat-unexposed cotwins of combat veterans with PTSD largely displayed the same performance as their brothers, which was significantly lower than that of non-PTSD combat veterans and their brothers. The results support the notion that specific domains of cognitive function may serve as premorbid risk or protective factors in PTSD.