Cognitive and Hippocampal Abnormalities in Posttraumatic Stress Disorder
Tu, Tiffany O.
- Objective: To determine whether cognitive and hippocampal abnormalities found in PTSD are familial vulnerability factors or acquired characteristics. Design: Cross-sectional twin paradigm including monozygotic twins discordant for combat exposure. Participants: Male combat-exposed veterans with PTSD (n=13) and their combat-unexposed co-twins (n=13), as well as combat-exposed veterans without PTSD ... read more(n=14) and their combat-unexposed co-twins (n=14). Main Outcome Measures: We used neurocognitive tests to measure declarative verbal learning, verbal fluency, and visuospatial copying ability. We used magnetic resonance imaging, positron emission tomography, and fluorodeoxyglucose-18 to examine hippocampal morphology, resting regional cerebral metabolic rate for glucose, and activation during a recognition memory task. Results: We found that PTSD twin pairs showed impaired initial encoding during a declarative verbal memory task compared to Control twin pairs. PTSD symptom severity in combat-exposed twins correlated negatively with verbal declarative memory performance in unexposed co-twins. We found no significant abnormalities in visuospatial copying ability, verbal fluency, or hippocampal structure or function. Conclusion: Impairment in initial encoding of verbal declarative memory seems to represent a familial vulnerability factor for developing PTSD after exposure to psychological trauma.read less