Two large studies of twins with Parkinson's disease confirmed the relative unimportance of genes as a primary cause in both studies, the pairwise concordance rate for identical twins was relatively low-6% and 17%-and in neither study, the rate differed significantly from the rate for the fraternal twins. Genes include SNCA, LRRK2, PRKN, PINK1, and GRA and account for only approximately 5% of cases, many of which manifest before the age of 60. It is known that genes as a primary cause are less important for Parkinson's disease than for many other diseases. Given this increase, it is important to ask what we know about the causes of Parkinson's disease. Part of the increase is due to the aging population, but demographics alone cannot explain the dramatic rise. The increase in cases, which has been called a “Parkinson pandemic”, has been most marked in wealthier European nations and in China. We believe such studies should be supported.Ī 2018 editorial in Lancet Neurology reported that “the prevalence, burden of disability, and number of deaths associated with Parkinson's disease all more than doubled between 19”. A search of Parkinsonian research studies currently funded by the US National Institutes of Health, Parkinson's Foundation, and the Michael J Fox Foundation yielded no studies on mercury. However, studies of patients are relatively few, and the need for research is clear. Published studies suggest some promising leads in the relationship between mercury exposure and Parkinson's disease. Relatively few studies have assessed mercury in parkinsonian patients, but almost all reported a statistically significant association.

It can also produce neurochemical and neuropathological changes similar to those found in Parkinson's disease, including the loss of dopamine neurons, degeneration of tubulin and axons, dysfunction of mitochondria, and the aggregation of alpha-synuclein. Mercury toxicity can produce tremors and other Parkinsonian clinical symptoms. It remains in the brain for many years and is known to produce permanent neuropsychological deficits. In both cases, mercury is known to get into the brain in utero and at all ages. For most people, our contemporary exposure to mercury comes from dental amalgam tooth restorations and from eating fish contaminated with mercury. We therefore undertook a review of this association, focusing especially on peer-reviewed articles to avoid the bias inherent in much of the literature regarding mercury. In reviewing the literature on heavy metals known to be toxicants, we noted several recent studies on mercury suggesting a possible role in the etiology of some cases of this disease. Environmental toxicants are thought to play a major role in the pathogenesis of Parkinson's disease.

Salmon and mercury poisoning