1) de Lau LM, Koudstaal PJ, Hofman A, Breteler MM. Subjective complaints precede Parkinson disease : the Rotterdam study. Arch Neurol 2006 ; 63 : 362-5.
2) Tolosa E, Compta Y, Gaig C. The premotor phase of Parkinson's disease. Parkinsonism Relat Disord 2007 ; 13 : 2-7.
3) Agid Y, Arnulf I, Bejjani P, et al. Parkinson's dis-ease is a neuropsychiatric disorder. Adv Neurol 2003 ; 91 : 365-70.
4) Hubble JP, Cao T, Hassanein RE, et al. Risk factors for Parkinson's disease. Neurology 1993 ; 43 : 1693-7.
5) Yang J, Wu Z, Lou X. A case-control study on risk factors in etiology of Parkinson's disease. Zhonghua Liu Xing Bing Xue Za Zhi 1994 ; 15 : 6-9. [Chinese]