title: Smaller hippocampal volume predicts pathologic vulnerability to psychological trauma.
abstract: In animals, exposure to severe stress can damage the hippocampus. Recent human studies show smaller hippocampal volume in individuals with the stress-related psychiatric condition posttraumatic stress disorder (PTSD). Does this represent the neurotoxic effect of trauma, or is smaller hippocampal volume a pre-existing condition that renders the brain more vulnerable to the development of pathological stress responses? In monozygotic twins discordant for trauma exposure, we found evidence that smaller hippocampi indeed constitute a risk factor for the development of stress-related psychopathology. Disorder severity in PTSD patients who were exposed to trauma was negatively correlated with the hippocampal volume of both the patients and the patients' trauma-unexposed identical co-twin. Furthermore, severe PTSD twin pairs-both the trauma-exposed and unexposed members-had significantly smaller hippocampi than non-PTSD pairs.
authors.affiliation: Research Service, Veterans Administration Medical Center, 718 Smyth Road, Manchester, New Hampshire 03104, USA. mark.gilbertson@med.va.gov
authors.forename: Mark W
authors.initials: MW
authors.lastname: Gilbertson
authors.forename: Martha E
authors.initials: ME
authors.lastname: Shenton
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Ciszewski
authors.forename: Kiyoto
authors.initials: K
authors.lastname: Kasai
authors.forename: Natasha B
authors.initials: NB
authors.lastname: Lasko
authors.forename: Scott P
authors.initials: SP
authors.lastname: Orr
authors.forename: Roger K
authors.initials: RK
authors.lastname: Pitman
mesh_terms: D000437:Alcoholism / Q000453:epidemiology; D003130:Combat Disorders / Q000453:epidemiology / Q000473:pathology; D015897:Comorbidity; D006624:Hippocampus / Q000002:abnormalities*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013313:Stress Disorders, Post-Traumatic / Q000453:epidemiology* / Q000473:pathology*; D019966:Substance-Related Disorders / Q000453:epidemiology; D014430:Twins, Monozygotic