The study, based on data from 36 million Medicare recipients, is both the first to produce any significant information on patterns of Parkinson's disease in minorities and to show geographic clusters for the condition.
"Finding clusters in the Midwest and the Northeast is particularly exciting," says lead author Allison Wright Willis, M.D., assistant professor of neurology at Washington University School of Medicine in St. Louis. "These are the two regions of the country most involved in metal processing and agriculture, and chemicals used in these fields are the strongest potential environmental risk factors for Parkinson's disease that we've identified so far."
The results appear online in the journal Neuroepidemiology.
Parkinson's disease is a common neurodegenerative condition that causes tremor, stiffness, slowness, mood and behavioral disorders, sleep problems and other symptoms. The disease is characterized by loss of dopamine, a compound involved in communication between brain cells.
According to Willis, genetic factors explain only a small percent of cases. Environmental factors are likely more common contributors and may include prolonged exposures to herbicides and insecticides used in farming or to metals such as copper, manganese and lead.
For the new study, Willis analyzed data on more than 450,000 cases of Parkinson's disease per year over six years, 1995 and 2000-2005. Collectively, that data included information from more than 98 percent of all Americans 65 and older.
Willis found Asians and blacks developed Parkinson's disease at half the rate of whites and Hispanics.
"We are going to try to learn more about why this is the case," says Willis. "It could be that those with Asian or African ancestry have genes that help protect them from exposure to environmental factors that cause Parkinson's disease, or they may have fewer exposures to those factors."
Epidemiologists have long debated whether Parkinson's disease is more prevalent in rural or urban areas, with some studies showing higher rates in cities and some in the countryside. Willis found the condition is more common in urban areas but concluded the comparison between the two rates offered little potential for insight into the disease.
"It's always been an open question as to how to best define the terms 'urban' and 'rural,'" she says. "Urban and rural is defined in many different and relatively arbitrary ways, and we came away convinced by our results that these distinctions have little to do with what is causing the disease."
Willis and her colleagues plan further studies of how exposure to single or combined environmental factors influences disease risk.
"This was the largest descriptive epidemiological study yet to be conducted of Parkinson's disease in the United States, and it has both given us some interesting new leads for the future research and reinforced some ideas we already had," she says.
Wright Willis A, Evanoff BA, Lian M, Criswell SR, Racette BA. Geographic and ethnic variation in Parkinson disease: a population-based study of US Medicare beneficiaries. Neuroepidemiology, 2010;34:143-151
Funding from the National Institute for Environmental Health Science, the National Institute of Neurological Disorders and Stroke, and the National Center for Research Resources supported this research.
Washington University School of Medicine's 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked third in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is linked to BJC HealthCare.
Michael C. Purdy | EurekAlert!
Europe’s Demographic Future. Where the Regions Are Heading after a Decade of Crises
10.08.2017 | Berlin-Institut für Bevölkerung und Entwicklung
Scientists reveal source of human heartbeat in 3-D
07.08.2017 | University of Manchester
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).
The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
16.08.2017 | Physics and Astronomy
16.08.2017 | Materials Sciences
16.08.2017 | Interdisciplinary Research