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The article discusses research to evaluate the risk of Parkinson's disease (PD) associated with tea consumption. PD is considered the second most frequent neurodegenerative disease at present, and its prevalence is expected to increase rapidly, given the growing proportion of elderly in many populations. The study found that drinking tea can protect against PD and this protective effect is clearer in Chinese populations.

Our aim was to estimate the pooled risk of current and former smoking for Parkinson's disease (PD).We have reviewed all observational studies that evaluated the association between PD risk and smoking habit. Twenty six studies were identified: 21 case-control, 4 cohort and 1 cross-sectional. The cross-sectional study did not compare former with never smokers. These studies were carried out between 1968 and 2000. There was an obvious protective effect of current smoking in the pooled estimate [risk estimate 0.37 (95% confidence interval 0.33 to 0.41)]. Former versus never smokers had pooled risk estimate of 0.84 (95% confidence interval 0.76 to 0.92). Current and former smoking do not, therefore, exert the same protective effect against PD so that it is unnecessary to postulate a biological mechanism through which smoking protects against PD. The results show that the reverse direction of causation is a more probable explanation, i.e. movement disorders of PD protect against smoking. Another explanation is that failure to develop strong smoking habits in early adult life might be a prodromal symptom of the disease and could perhaps be its first clinical manifestation. [ABSTRACT FROM AUTHOR]

Perhaps one of the most important questions posed by the neurobiology of aging concerns the pathogenic mechanisms in Parkinson's disease (PD). Recently, it was suggested that exposure to pesticides could be the main cause of PD. Another study reported that the environmental endotoxin, lipopolysaccaride produced by Salmonella minnesota, might be a risk factor for PD. An alternative explanation is the genetic component, which has been suggested to be an important risk factor. Epidemiological studies have identified a positive family history of Parkinson as one of the most important risk factors for the disease. However, these studies neither examined nor reviewed the medical records of the family members. The twin study stated that the major factors in the etiology of PD are non-genetic. Meanwhile, epidemiological studies from China have shown that the prevalence of PD is much lower than in the Caucasian population, explained by the low frequency of cytochrome P-450 CYP2D6 debrisoquine hydroxylase gene polymorphism. The etiology of idiopathic PD is still a question for scientists, and calls for further research, especially with the growing proportion of elderly and the rising incidence of PD worldwide. Future research for PD risk factors should consider that multiple interactions occur in PD, resulting in a complex trait, which includes genetic, acquired, and environmental components. [ABSTRACT FROM AUTHOR]