The relation of putamen and caudate nucleus F-18-Dopa uptake to motor and cognitive performances in Parkinson's disease

The contribution of striatal (caudate nucleus-putamen) dopaminergic deficie ncy to the severity of motor signs is well established in Parkinson's disea se (PD), while its role in the occurrence of cognitive and mood changes rem ains unresolved. We therefore measured in 27 non-demented PD patients and 1 0 age-matched controls striatal uptake of [F-18]-6-fluoro-L-Dopa (F-Dopa) w ith PET, and mood (Beck depression), memory (Grober-Buschke), frontal execu tive functions (verbal fluency and Wisconsin card sorting), and attentional processing of sensory stimuli (N2-P3 auditory event-related potentials - E RPs). Locomotor disability of patients was assessed by Hoehn and Yahr score and Unified Parkinson's Disease Rating Scale (UPDRS), ANOVA showed that me mory, but neither frontal lobe functions nor ERPs, was significantly altere d in PD patients, whereas indices of depression were found only in advanced PD. The F-Dopa rate constant K-i was significantly reduced in the striatum , more in putamen than caudate nucleus, and inversely correlated with disea se duration. A significant inverse correlation was found between both putam en and caudate nucleus Ki and Hoehn and Yahr score, and between putamen - b ut not caudate nucleus K-i - and UPDRS motor score, Principal components an alysis (PCA) of PD patients K-i values and mood, cognitive and ERP paramete rs gave a three-factor solution. Variables contributing to factor 1 were me mory score and N2-P3 ERP latencies, those to factor 2 were striatal K-i val ues, and those to factor 3 frontal executive performances. Depression did n ot segregate with any variable. Our findings suggest that unlike locomotor disability, cognitive abilities and mood state of non-demented PD patients are for the most part unrelated to striatal dopaminergic depletion and may result from dysfunction of extra-striatal dopaminergic or from non-dopamine rgic systems. (C) 1999 Elsevier Science B.V. All rights reserved.