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MRS of PTSD Research
Magnetic resonance spectroscopy (MRS) of the hydrogen atom is a noninvasive technique related to MRI for the in vivo measurement of the concentration of various metabolites in the human brain. One compound of great interest is N-acetylaspartate (NAA), which is only found in neurons in the adult brain. Loss of the NAA signal in the MRS spectrum (Figure 1) is typically accepted as a measure of neuronal loss or damage. In collaboration with Dr. Tom Freeman in the Department of Psychiatry and the Veteran's Hospital, Drs. Richard Komoroski and Diana Lindquist are using MRS to measure the concentration of NAA (relative to Cr) in the medial temporal lobe (MTL), including hippocampus, of patients with PTSD and matched control subjects. The MRI scans in Figure 2 show the typical location of the volume element, or voxel, from which the MRS data is taken. In our first study1, we found that the ratio NAA/Cr was reduced in the right MTL of Vietnam combat veterans with PTSD, relative to both left MTL for those same veterans and right MTL for control veterans (Figure 3). In a more recent study2 of POWs with and without PTSD, we found that NAA/Cr did not differ between POWs with PTSD and POW controls without PTSD for either right or left MTL. However, NAA/Cr in both right and left MTL for PTSD subjects correlated with re-experiencing symptoms as measured with the Clinician Administered PTSD Scale (CAPS-2).
 Figure 2. Coronal (a) and sagittal (b) MRI scans of a patient with PTSD showing a typical location in the MTL, including the hippocampus, of the 2x2x3 cm3 voxel used to acquire the MRS spectrum.  Figure 3. Plot of the individual results for the peak-area ratio NAA/Cr for right and left MTLs in patients with PTSD and controls.
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Posttraumatic Stress Disorder Introduction
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