Previous studies have shown that tea drinking is associated with a reduced of risk for Parkinson's disease (PD). Green tea polyphenols (GTPs), the major components of green tea, have been shown to protect against neuronal loss both in cultures and pre-clinical models after exposed to toxins that selectively damage dopaminergic neurons. The goal of the project is to assess the ability of GTPs to slow the disease progression and its safety and tolerability in patients with early PD in a randomized, double-blind, placebo-control, multi-center study in China.
Approximately 400 PD patients will be investigated. The groups receiving different doses of the active drug will continue their assigned therapy for the full 12 months. Controls will receive placebo for the first six months of therapy, followed by GTPs for a full six months to 'catch up' to the other groups.
If the GTPs are neuroprotective, the groups receiving active drug for the full 12 months should maintain their 'head start,' and thus there should still be a difference in change of UPDRS and disability at the end of 12 months.
To evaluate the safety, tolerability and efficacy of green tea polyphenols (GTPs) in slowing disease progression in patients with early PD, the team carried out a multi-center, double-blind, randomized, placebo-controlled, delayed-start study in 32 Chinese Parkinson Study Group (CPSG) sites. Study enrollees were 410 untreated PD patients with disease duration of less than five years and Hoehn & Yahr stage below 3 who were not heavy tea drinkers. Participants were randomized to one of three doses of GTP (0.4, 0.8 or 1.2 grams daily given in two equal oral doses) or matching placebo. After six months, placebo was switched to 1.2 grams daily of GTP. All patients were treated for 12 months.
The change in total UPDRS score from randomization to six months was significantly improved in GTP-treated groups as compared to the placebo group, but this was not observed at 12 months. In the delayed-start group, the change in UPDRS from six months (the start of active GTP) to 12 months was significantly improved. Insomnia was slightly increased in GTP-treated patients, but there were no other significant differences in adverse effects. GTP is well tolerated and appears to provide, at least, a mild symptomatic benefit in early untreated PD.