Simple movement sequences better correlate to levodopa plasma levels than complex ones

Instrumental assessment of movements with a computer based device reflect the clinical response of patients with Parkinson's disease (PD) to dopaminergic stimulation. We investigated associations between levodopa plasma levels, scored motor symptoms of upper limbs and instrumental test outcomes after dopaminergic stimulation. Clinical rating scores, test outcomes for simple and complex motion series significantly improved after oral application of 250 mg of a water soluble, fast absorbed levodopa/benserazide preparation, which induced a significant increase of levodopa in plasma during a two hour interval. There was a significant association between the computed area under the curve-values of levodopa plasma concentrations and test results for simple-, but not for complex movement sequences. Performance of complex motion series additionally ask for concomitant cognitive efforts with consecutive hypothetical involvement of extranigral non dopaminergic systems. In contrast, practice of simple movements is more directly associated to the predominantly dopamine regulated motor system.