ABNORMAL CEREBRAL METABOLITE CONCENTRATIONS IN PATIENTS WITH PROBABLE ALZHEIMER-DISEASE

To establish whether recently described abnormalities of peak ratios are the result of changes in metabolite concentrations, quantitative H-1 magnetic resonance spectroscopy was performed in 10 patients with Alzheimer disease (AD) and seven normal elderly. CSF volumes, metabolite T-1 and T-2 relaxation rates, ratios and concentrations of N-acetyl residues, creatine, choline residues, myo-inositol, glutamine plus glutamate (Glx), and glucose were obtained. Difference spectroscopy and quantitative 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 reduction in beta,gamma-Glx and a significant increase in intracerebral [glucose], greater than attributable to CSF, were defined. Choline concentration increased with age, but was not elevated above normal in AD patients. These findings indicate the need for quantitative H-1 MRS to substantiate metabolite ratios. The increased myo-inositol concentration in AD is demonstrated by these studies.