Differential effect of caffeine intake in subjects with genetic susceptibility to Parkinson's Disease.

We examined if caffeine intake has a differential effect in subjects with high and low genetic susceptibility to Parkinson's disease (PD), a common neurodegenerative disorder. A case control study involving 812 subjects consisting of PD and healthy controls were conducted. Caffeine intake assessed by a validated questionnaire and genotyping of PD gene risk variant (LRRK2 R1628P) was carried out. Compared to caffeine takers with the wild-type genotype (low genetic susceptibility), non-caffeine takers with R1628P variant (high genetic susceptibility) had a 15 times increased risk of developing PD (OR = 15.4, 95% CI = (1.94, 122), P = 0.01), whereas caffeine takers with R1628P (intermediate susceptibility) had a 3 times risk (OR = 3.07, 95% CI = (2.02, 4.66), P < 0.001). Caffeine intake would significantly reduce the risk of PD much more in those with high genetic susceptibility compared to those with low genetic susceptibility.