Smaller hippocampal volume predicts pathologic vulnerability to psychological trauma.
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.
Gilbertson
Mark W
MW
Research Service, Veterans Administration Medical Center, 718 Smyth Road, Manchester, New Hampshire 03104, USA. mark.gilbertson@med.va.gov
Shenton
Martha E
ME
Ciszewski
Aleksandra
A
Kasai
Kiyoto
K
Lasko
Natasha B
NB
Orr
Scott P
SP
Pitman
Roger K
RK
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