Context: Recent neuroimaging research has revealed functional abnormalities in the anterior cingulate cortex, amygdala, and hippocampus in individuals with posttraumatic stress disorder (PTSD).
Objective: To determine whether resting functional abnormalities found in PTSD are acquired characteristics or familial risk factors.
Design: Cross-sectional design including identical twins discordant for trauma exposure.
Setting: Academic medical center.
Participants: Combat-exposed veterans with PTSD (n = 14) and their identical co-twins not exposed to combat (n = 14) as well as combat-exposed veterans without PTSD (n = 19) and their identical co-twins not exposed to combat (n = 19).
Main outcome measures: We used positron emission tomography and fluorodeoxyglucose 18 to examine resting regional cerebral metabolic rate for glucose (rCMRglu).
Results: Veterans with PTSD and their co-twins had significantly higher resting rCMRglu in the dorsal anterior cingulate cortex/midcingulate cortex (dACC/MCC) compared with veterans without PTSD and their co-twins. Resting rCMRglu in the dACC/MCC in unexposed co-twins was positively correlated with combat exposure severity, PTSD symptom severity, and alcohol use in their exposed twins.
Conclusions: Enhanced resting metabolic activity in the dACC/MCC appears to represent a familial risk factor for developing PTSD after exposure to psychological trauma.