title: Coenzyme Q10 for Parkinson's disease.
abstract: BACKGROUND
  A number of preclinical studies in both in vitro and in vivo models of Parkinson's disease have demonstrated that coenzyme Q10 can protect the nigrostriatal dopaminergic system. Some clinical trials have looked at the neuroprotective effects of coenzyme Q10 in patients with early and midstage Parkinson's disease.
  
  
  OBJECTIVE
  To assess the evidence from randomized controlled trials on the efficacy and safety of treatment with coenzyme Q10 compared to placebo in patients with early and midstage Parkinson's disease.
  
  
  METHODS
  We searched the Cochrane Movment Disorders Group Trials Register, CENTRAL (The Cochrane Library 2009, Issue 4), MEDLINE (January 1966 to March 2011), and EMBASE (January 1985 to March 2011). We handsearched the references quoted in the identified trials, congress reports from the most important neurological association and movement disorder societies in Europe and America (March 2011), checked reference lists of relevant studies and contacted other researchers.
  
  
  METHODS
  We included randomized controlled trials (RCTs) that compared coenzyme Q10 to placebo for patients who suffered early and midstage primary Parkinson's disease. Studies in which the method of randomization or concealment were unknown were included. Cross-over studies were excluded.
  
  
  METHODS
  Two review authors independently assessed trial quality and extracted data. All disagreements were resolved by consensus between authors and were explained. We attempted to contact the authors of studies for further details if any data were missing and to establish the characteristics of unpublished trials through correspondence with the trial coordinator or principal investigator. Adverse effects information was collected from the trials.
  
  
  RESULTS
  Four randomized, double-blind, placebo-controlled trials with a total of 452 patients met the inclusion criteria and were included in the review. In overall, there were improvements in activities of daily living (ADL) UPDRS (WMD -3.12, 95% CI -5.88 to -0.36) and Schwab and England (WMD 4.43, 95% CI 0.05 to 8.81) for coenzyme Q10 at 1200 mg/d for 16 months versus placebo.In safety outcomes, only the risk ratios (RR) of pharyngitis (RR 1.04, 95% CI 0.18 to 5.89) and diarrhea (RR 1.39, 95% CI 0.62 to 3.16) are mild elevated between coenzyme Q10 therapy and placebo and there were no differences in the number of withdrawals due to adverse effects (RR 0.61, 95% CI 0.23 to 1.62).
  
  
  CONCLUSIONS
  Coenzyme Q10 therapy with 1200 mg/d for 16 months was well tolerated by patients with Parkinson's disease. The improvements in ADL UPDRS and Schwab and England were positive, but it need to be further confirmed by larger sample. For total and other subscores of UPDRS, the effects of coenzyme Q10 seemed to be less clear.
authors.affiliation: Department of Geriatric Neurology, Chinese PLA General Hospital, Fuxinglu 28, Beijing, China, 100853.
authors.forename: Jia
authors.initials: J
authors.lastname: Liu
authors.forename: Luning
authors.initials: L
authors.lastname: Wang
authors.forename: Si-Yan
authors.initials: SY
authors.lastname: Zhan
authors.forename: Yinyin
authors.initials: Y
authors.lastname: Xia
mesh_terms: D000203:Activities of Daily Living; D003967:Diarrhea / Q000139:chemically induced; D006801:Humans; D018696:Neuroprotective Agents / Q000009:adverse effects / Q000627:therapeutic use*; D010300:Parkinson Disease / Q000188:drug therapy*; D010612:Pharyngitis / Q000139:chemically induced; D016032:Randomized Controlled Trials as Topic; D014451:Ubiquinone / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D014815:Vitamins / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D018696:Neuroprotective Agents; D014815:Vitamins; D014451:Ubiquinone; C024989:coenzyme Q10