Exploring Trauma's Cerebral Side
Bower, Bruce, Science News
New studies suggest that people who fall prey to a severe stress reaction following military combat or sexual abuse have an unusually small hippocampus, a brain structure that helps to regulate memory. But scientists cannot say yet whether severe trauma causes the hippocampus to shrink or whether a small hippocampus somehow contributes to vulnerability to trauma.
In a brain scan investigation directed by Murray B. Stein of the University of California, San Diego, 22 women who cited repeated childhood sexual abuse displayed hippocampal volumes smaller by 5 percent than those of 20 women who reported no sexual abuse and no psychiatric disorders. Similar findings appeared last year (SN: 6/3/95, p. 340).
Sixteen of these sexually abused women suffered from post-traumatic stress disorder (PTSD). Hippocampal volume was lowest in those reporting the most severe dissociation, Stein asserts. Dissociation includes feelings of detachment from one's self and other alterations of consciousness. Women abused as young children performed better on short-term memory tasks than those abused at later ages. The brains of young children may have more resilience to trauma than those of teenagers or adults, Stein theorizes.
Another study, directed by Tamara V. Gurvits of the Veterans Affairs Medical Center in Manchester, N.H., found a 24 percent smaller hippocampal size in seven Vietnam combat veterans suffering from PTSD, compared to seven Vietnam combat veterans free of PTSD and eight men who did not serve in the military. …