ABNORMAL CEREBRAL METABOLITE CONCENTRATIONS IN PATIENTS WITH PROBABLEALZHEIMER-DISEASE

To establish whether recently described abnormalities of peak ratios a re the result of changes in metabolite concentrations, quantitative H- 1 magnetic resonance spectroscopy was performed in 10 patients with Al zheimer disease (AD) and seven normal elderly. CSF volumes, metabolite T-1 and T-2 relaxation rates, ratios and concentrations of N-acetyl r esidues, creatine, choline residues, myo-inositol, glutamine plus glut amate (Glx), and glucose were obtained. Difference spectroscopy and qu antitative assays showed a 50% increase in myo-inositol (6.4-9.8 mM; P < 0.005) and a decrease in N-acetyl in occipital gray matter. A reduc tion in beta,gamma-Glx and a significant increase in intracerebral [gl ucose], greater than attributable to CSF, were defined. Choline concen tration increased with age, but was not elevated above normal in AD pa tients. These findings indicate the need for quantitative H-1 MRS to s ubstantiate metabolite ratios. The increased myo-inositol concentratio n in AD is demonstrated by these studies.