From the Service Hospitalier Frederic Joliot CEA, Departement de Biologie, Orsay, t and the Clinique de

SUMMARY Using the '8f-fluoro-2-deoxy-d-glucose technique and positron emission tomography (PET), the local cerebral glucose utilisation (lCMRGlc) was measured in four non-demented patients with early-onset, bilateral Parkinson's disease characterised by the predominance of akinesia. The study was done twice, first in the untreated condition, and then after levodopa had been resumed. Despite a marked clinical improvement, we found no alteration in lCMRGlc between the first and second studies in any of the brain structure analysed. Compared to control values, lCMRGlc in the basal ganglia was moderately increased in both studies. These essentially negative findings agree with most previous human or animal studies, and indicate that the func-tional alterations in the central dopaminergic systems of patients with Parkinson's disease have metabolic correlates that are too small to be demonstrated by current PET devices. The typical symptomatic triad of Parkinson's dis-ease, that is akinesia, rigidity, and tremor, implies that functional alterations take place in certain cere-bral structures. Since energy metabolism in the brain has been shown to be coupled to function, ' change