Is Parkinson's disease acquired? Evidence from a geographic comparison with multiple sclerosis.

In the coterminous United States, MS mortality rates demonstrate a north-south gradient, which is confirmed by more sophisticated--and more expensive--prevalence studies. Mortality rates from idiopathic Parkinson's disease show a similar north-south gradient, and they correlate significantly with the MS mortality and prevalence data. This demonstration that Parkinson's disease may be place-related provides support for the hypothesis that Parkinson's disease, like MS, is an acquired, environmental illness.