This is a no-brainer. Hope someone with PD insists their doctor try this.
The FDA can't possibly object.

http://www.neurores.org/index.php/ne...rticle/155/156

Note that our PD patients improved dramatically in a short time with thiamine supplements. Days after thiamine treatment, they smiled and walked normally with longer steps, and increased arm swings, and no tremors or sialorrhea was reported. Three patients did not receive carbidopa plus levodopa and cessation of those medications did not effect on their movements. The most effective treatment for PD is levodopa in combination with a peripheral decarboxylase inhibitor (carbidopa or benserazide). In a murine model, dopamine has been reported to suppress mouse-killing aggression (muricide) induced by a thiamine-deficient (TD) diet [8]. This suppressive effect can be potentiated with carbidopa [9]. Patients with PD who have undergone levodopa therapy have significantly higher cerebrospinal fluid (CSF) levels of thiamine diphosphate (TDP) and total thiamine than those patients who were not treated with this drug [1]. Moreover, thiamine deficiency can decrease the concentration of dopamine in the striatum, whereas animals fed on a diet that contained 5% ethanol exhibit increased dopamine turnover [10]. In an experimental TD study, a region-specific vesicular dysfunction (i.e., decreased levels of dopaminergic metabolites) was observed [11]. Dopamine release ii induced by intrastriatal administration of TPP or TDP (up to 1400% and 249% of the basal levels, respectively), reduced dopamine levels in the striatum may occur in cases of thiamine deficiency [12].