Traumatic Stress Induces Brain Change in Children

STANFORD, Calif., March 5 -- Children with post-traumatic stress disorder, similar to adults, show physical changes in the brain, according to researchers here.

In a pilot study of 15 children, higher PTSD scores and higher cortisol levels were significantly (P<0.05) correlated with relative decreases over time in the volume of the right hippocampus, reported Victor Carrion, M.D., of Stanford, and colleagues, reported in the March issue of Pediatrics.

On the other hand, there was no correlation with changes in the left hippocampal volume, Dr. Carrion and colleagues found.

In adults, PTSD is associated with lower hippocampal volumes compared with adults who do not have stress disorder, Dr. Carrion and colleagues noted, but such a relation hasn't been shown in children.

Because animal studies show that the stress hormone cortisol can be neurotoxic to the hippocampus, the researcher hypothesized that children with high levels of cortisol at the beginning of a 12- to 18-month study period would show changes in hippocampal volume.

They enrolled 15 children (nine girls) with an average age of 10.4 and a PTSD score of 12 or greater on the PTSD Reaction Index. The children's stress scores -- including hyperarousal -- were evaluated using the Clinician-Administered PTSD Scale for Children and Adolescents.

The children were suffering from PTSD after undergoing physical, emotional or sexual abuse, witnessing violence, or experiencing lasting separation and loss, Dr. Carrion said.

"We're not talking about the stress of doing your homework or fighting with your dad," Dr. Carrion said. "We're talking about traumatic stress. These kids feel like they're stuck in the middle of a street with a truck barreling down at them."

Cortisol was measured by taking saliva swabs four times a day for three days at the beginning of the study, Dr. Carrion and colleagues said, and hippocampal volume was measured at the beginning and end of the study using magnetic resonance imaging.

The researchers calculated hippocampal volume changes both as a simple subtraction of the end volume from the beginning volume and adjusted to account for maturation and sex. The changes were then examined for possible correlation with severity of PTSD, hyperarousal, and initial cortisol levels.

Analysis found:

• None of the PTSD markers was associated with the left hippocampal volume.
• PTSD scores and cortisol levels were correlated with simple hippocampal volume changes at P<0.05, and hyperarousal was correlated at P<0.01.
• All three markers were correlated with the adjusted hippocampal volume change at P<0.05.

Dr. Carrion said the study is "a snapshot" of the effect of PTSD on the young brain, and cannot say anything about functional changes in memory processing and emotion.

"One common treatment for PTSD is to help a sufferer develop a narrative of the traumatic experience," he said. "But if the stress of the event is affecting areas of the brain responsible for processing information and incorporating it into a story, that treatment may not be as effective."

He said future research may find better ways to help children with PTSD, as well as uncovering the reasons that some children are more resilient than others.