Lower risk of Parkinson's disease in an admixed population of European and Indian origins

We studied whether the occurrence of Parkinson's disease (PD) in the Anglo-Indians, an admixed population of European and Asian Indian origin, differs from Indians living in the same environment. Epidemiological studies show considerably higher prevalence of PD amongst white compared to non-white populations. Normal Indians contain a similar to40% lower number of melanized nigral neurons compared to Caucasians from the UK. Anglo-Indians are an admixed population of European and Indian origin. We used the UK Parkinson's Disease Society Brain Bank clinical diagnostic criteria (steps 1 and 2) to diagnose PD in 84 of 493 residents (Indians, 409; Anglo-Indians, 84) living in elderly homes in Bangalore, India. Of these 84, 80 were Indians (19.5%) and 4 were Anglo-Indians (4.8%). Occurrence of PD is nearly five times higher amongst Indians compared to the Anglo-Indians (odds ratio, 3.9; 95% confidence interval, 1.3-12.9). We conclude that an admixture population of European and Indian origins, rather than averaging, might result in reduced occurrences of PD. Hence, studying an admixed population could provide crucial insights into understanding genetic mechanisms in the etiopathogenesis of PD. (C) 2003 Movement Disorder Society.