title: Levodopa and executive performance in Parkinson's disease: a randomized study.
abstract: Parkinson's disease (PD) patients may experience fluctuations in executive performance after oral levodopa (LD). Their relationship with the pharmacokinetic profile of LD and with distinct cognitive processes associated with frontal-basal ganglia circuits is not well understood. In this randomized, double-blind, crossover study we plotted acute cognitive changes in 14 PD patients challenged with faster (immediate-release, IR) versus slower (controlled-release, CR) increases in LD plasma concentrations. We monitored motor status, LD plasma levels, and performance on four tasks of executive function (Wisconsin Card Sorting Test-WCST, Sternberg test, Stroop and Tower of Hanoi), 1 hr before and over +6 hr after IR and CR-LD dose. Analysis of variance demonstrated significant but divergent changes in the Sternberg (6-digit but not 2- and 4-digit) test: improvement after CR-LD and worsening after IR-LD. Marginal improvement (p = .085) was observed with CR-LD in the WCST, while no significant differences were seen for the Stroop or Tower of Hanoi tests. Executive-related performance after LD challenge may differ depending on the LD time-to-peak plasma concentration and specific task demands. A slower rise in LD levels appears to have a more favorable impact on more difficult working memory tests. These results require replication to determine their generalization.
authors.affiliation: Department of Neurology (Movement Disorders Unit) and CIBERNED, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, Spain.
authors.forename: Berta
authors.initials: B
authors.lastname: Pascual-Sedano
authors.forename: Jaime
authors.initials: J
authors.lastname: Kulisevsky
authors.forename: Manel
authors.initials: M
authors.lastname: Barbanoj
authors.forename: Carmen
authors.initials: C
authors.lastname: García-Sánchez
authors.forename: Antonia
authors.initials: A
authors.lastname: Campolongo
authors.forename: Alexandre
authors.initials: A
authors.lastname: Gironell
authors.forename: Javier
authors.initials: J
authors.lastname: Pagonabarraga
authors.forename: Ignasi
authors.initials: I
authors.lastname: Gich