race. In preliminary interviews, the researchers asked the kids or their caregivers about PTSD symptoms and hyperarousal symptoms like difficulty sleeping, irritability, and trouble concentrating, to name just a few. Then they did an MRI and checked each kid’s salivary cortisol four times a day. Once the brain scans were in, they looked at the size of each child’s hippocampus by measuring the volume in 3-D. They found that the more symptoms a kid had, the higher his cortisol levels were and the smaller the volume of his hippocampus.
