Proton MR spectroscopy of the brain in 14 patients with Parkinson disease.

PURPOSE To determine whether the proton spectra from patients with clinically diagnosed Parkinson disease differ from the spectra of age-matched healthy subjects with respect to the major cerebral metabolite resonances as well as lactate. METHODS Fourteen patients with Parkinson disease (38 to 81 years of age) and 13 healthy control subjects (37 to 81 years of age) were studied using image-guided, single-voxel (27-cm3 volume) proton MR spectroscopy of the occipital lobe. RESULTS The peak area ratios of N-acetyl aspartate to creatine and N-acetyl aspartate to choline for Parkinson patients did not show a statistically significant difference from the corresponding ratios for control subjects. There was a very significant increase in the ratio of lactate to N-acetyl aspartate for patients with Parkinson disease, with the greatest increase (threefold) manifested by the subgroup (n = 4) with dementia. The difference in N-acetyl aspartate to choline between women (n = 7) with Parkinson disease and healthy women (n = 9) approached significance. No dependence of the peak ratios on age, duration of Parkinson disease, or medication (L-dopa) regimen was found. CONCLUSION Preliminary results indicating an increase in cerebral lactate in patients with Parkinson disease support the hypothesis that Parkinson disease is a systemic disorder characterized by an impairment of oxidative energy metabolism. The larger increases for Parkinson patients with dementia may be diagnostically useful in assessing clinical course and in differentiating Parkinson disease from other causes of dementia. Additional studies are needed, though, to quantitate lactate changes and identify potential contributions from lipid resonances better.