No change in striatal glutamate in Huntington's disease measured by proton magnetic resonance spectroscopy

The combined caudate head and anterior putamen of six patients with Huntington's disease (HD) was studied by quantitative magnetic resonance spectroscopy (MRS) and the spectra compared with those from a group of six age-matched normal subjects. The concentrations of the three major metabolites, choline, creatine and N-acetylaspartate (NAA), were quantified using tissue water as an internal concentration reference. Glutamate concentration was assessed as the (glutamate+glutamine)/creatine peak area ratio (Glx/Cre). In normal subjects the mean (+/-SD) concentrations of the three metabolites were 1.8+/-0.4mumol/g wet weight for choline, 11.9+/-1.4 for creatine and 14.1+/-2.4 for NAA. The ratio Glx/Cre was 1.3+/-0.3. The concentrations of both creatine and NAA were significantly lower in the striatum of patients with HD, 8.9+/-1.5 and 12.1+/-1.5 respectively. There was, however, no difference in choline concentration or in the Glx/Cre ratio, 1.7+/-0.4 and 1.6+/-0.5 respectively. The results are discussed in relation to the mechanism of neuronal loss in HD.