Fascinating podcast on Australia's Sept. 10 2005 All in the Mind program on Children, Teenagers and Anxiety. Natasha Mitchell interviewed Duke's Michael De Bellis about some brain imaging he'd done with PTSD & non-PTSD kids.
Turns out PTSD kids' brains are larger than "normal" kids' brains in some areas and smaller in others. For example, the "superior temple" is larger, which is where facial & social perception occurs; the hippocampus is also larger, which is where memory of time & place are stored. The PTSD kids had "smaller brains, smaller cerebral cortex, smaller cerebellums."
Although the interview doesn't indicate how De Bellis measured the brains, this podcast seem show how theoretical cognitive psychology can have some practical applications.
The link above goes to the transcript, but the ABC Radio National's main page includes links to a Real Audio stream, and mp3 file, and the podcast. Check out the other shows, too -- they're generally more applied psychology than cognitive, but they're pretty well done.