Increased pineal Fdopa uptake is related to severity of Parkinson's disease - A PET study

We investigated regional L-3,4-dihydroxy-6-[F-18]fluoro-phenylalanine (Fdopa) uptake within the pineal gland using co-registration of Fdopa PET and MRI images. Data from 12 early Parkinson's disease (PD) and 9 advanced PD patients were compared with those from 13 age-matched healthy controls. We found a significant increase of Fdopa influx constants: (K,) and relative Fdopa tracer activity in the pineal gland of PD patients. Additionally, significant correlations were found between Ki and the Hoehn and Yahr (H&Y) scores. and between the relative Fdopa activity and the parameters disease duration, H&Y disease score and Unified Parkinson's Disease Rating Scale (UPDRS). Our studies in patients with PD indicate a participation of extrastriatal dopaminergic structures within the scope of pathophysiological processes in PD. The result may be explained as a compensatory upregulation of monoaminergic transmitter systems outside the basal ganglia. Increased Fdopa uptake in the pineal gland may reflect pineal dysfunction in PD patients.