In vivo proton nuclear magnetic resonance (NMR) spectroscopy studies of scrapie in a mouse model have shown the appearance of an abnormal peak in the brain early in the incubation period. This abnormal peak was detected weeks before the detection of a protease-resistant form of a membrane protein and vacuolar histopathology in vitro, and several months before clinical signs, and the signal increased in intensity as the disease progressed. In the chronic stage of the disease, a reduction in N-acetyl aspartate levels was observed using in vivo and in vitro proton NMR spectroscopy.