We appreciate the thoughtful comments from Drs Horstink and van Engelen and Dr Hunter on our study of the effects of CoQ10 on patients with early PD.
Drs Horstink and van Engelen raise the question regarding whether the effect on the total UPDRS score that we found in our study could have been due to a symptomatic effect of CoQ10.They provide data from their study of 12 patients with PD who received 1000 mg/d of CoQ10 for 3 months and then 1500 mg/d for an additional 3 months, which they consider to indicate a minor clinical improvement. We find it difficult to agree with the interpretation that their data demonstrate a symptomatic effect of CoQ10 for several reasons. First, the study was open label. Second, the study lacked a placebo control group; a placebo effect in studies of PD is well recognized.1 Third, their analysis of the variables revealed that "none improved when analyzed using multiple comparisons techniques."
Shults CW, Haas R, Oakes D, et al. The Effect of Coenzyme Q10 Therapy in Parkinson Disease Could Be Symptomatic—Reply. Arch Neurol. 2003;60(8):1172–1173. doi:10.1001/archneur.60.8.1172
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