Parkinson's disease research in a prospective cohort in China

China has the largest population of Parkinson's disease (PD) patients; however few etiological studies of PD have been conducted in China.

The Shanghai Women's Health Study recruited 74,941 women in urban Shanghai, aged 40 to 70, from 1996 to 2000. Self-reported PD cases were invited for a neurological examination and diagnoses were made by a movement disorder specialist.

This cohort had very few smokers (2.7%), alcohol drinkers (2.3%), and post-menopausal hormone users (4.3%); however, tea drinking (29.9%) and exposure to tobacco smoke from husbands (61.8%) were common. A total of 301 participants reported PD diagnosis during the follow-up. The diagnosis was confirmed in 76 (57%) of the 133 clinically examined patients. An additional 19 (53%) PD cases were identified out of 36 participants who self-confirmed the diagnosis and provided a history on PD symptoms and treatments. As expected, increasing age was strongly associated with PD risk. Further, PD risk appears to be inversely associated with exposures to second-hand tobacco smoke from husbands and tea drinking, and positively with education, although none of these reached statistical significance. The age-adjusted odds ratio (OR) was 0.7 (95% confidence interval: 0.4-1.1) for participants whose husbands were current smokers at baseline and 0.8 (0.5-1.3) for ever tea-drinkers. Compared with primary education or lower, the age-adjusted OR was 1.3 (0.7-2.4) for middle school and 1.6 (1.0-2.7) for high school or above.

PD research in this unique cohort is feasible and, with extended follow-up, will allow for prospective PD etiological research in China.