In vivo proton magnetic resonance spectroscopy of the medial temporal lobes of subjects with combat-related posttraumatic stress disorder.

Recent findings using volumetric MRI techniques have revealed that patients with combat-related and noncombat-related posttraumatic stress disorder (PTSD) have reductions in right hippocampal volume. Twenty-one veterans with PTSD and eight age-matched control veterans were studied using proton magnetic resonance spectroscopy to test the hypothesis that the N-acetyl-L-aspartic acid/creatine (NAA/Cr) ratio would be decreased in the right medial temporal lobe structures of patients with PTSD compared to controls. Patients with PTSD displayed significantly lower NAA/Cr ratio for the right medial temporal lobe relative to the left (P < or = 0.011). Patients with PTSD also had lower NAA/Cr in right medial temporal lobe (P < or = 0.013) and lower choline/Cr in left medial temporal lobe (P < or = 0.030) compared to control subjects. Because NAA is regarded as an indicator of neuronal density, this finding suggests that the neuronal density of right-sided medial temporal structures in patients with combat-related PTSD may be decreased.