Parkinson's, Dementia & Mental Health
New Report Confirms Chemical Exposure Linked to Parkinson’s Disease
National Institutes of Health study finds trichloroethylene (TCE) and perchloroethylene (PERC) are culprits
Nov. 14, 2011 - A research report being published today confirms previous
evidence that occupational exposure to certain
chemical solvents increases the risk of Parkinson’s disease. The disease, for example, was nine times more common in a twin exposed to
trichloroethylene (TCE) and perchloroethylene (PERC) than one who was not. It most often strikes senior citizens.
Researchers analyzed the occupational histories of twins in which one of the pair developed the neurodegenerative
disorder, and assessed that twin's likelihood of exposure to six chemicals previously linked to Parkinson's.
Of the six chemicals investigated, researchers concluded that two common chemical solvents, trichloroethylene (TCE) and
perchloroethylene (PERC), are significantly linked to development of this disease.
This study, supported in part by the National Institute of Neurological Disorders and Stroke (NINDS), a part of the
National Institutes of Health, appears in the Nov. 14, 2011 issue of Annals of Neurology.
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More archived
news reports about Parkinson's disease below news story.
Read the latest news on
Alzheimer's, Dementia & Mental Health |
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Parkinson's disease is a movement disorder caused by the loss of brain cells that produce a molecule called dopamine. The
primary symptoms of Parkinson's are tremor, stiffness, slowed movement and impaired balance, and as these symptoms progress, patients may also
develop difficulty walking, speaking or completing other activities of daily living.
Genes play a role in Parkinson’s disease, but fewer than 10 percent of cases are due to a single gene mutation, and not
all people with these mutations develop Parkinson’s, suggesting that environmental factors also contribute to the likelihood of developing the
disease.
The researchers, led by Samuel Goldman, M.D., M.P.H. and Caroline Tanner, M.D., Ph.D. at the Parkinson's Institute in
Sunnyvale, Calif., collected the histories of 99 pairs of twins in which one of the pair developed Parkinson’s and the other twin did not.
Since twins are so genetically similar, twin studies are especially useful in identifying environmental influences in
disease. The twins were identified through the National Academy of Sciences/National Research Council World War II Veteran Twins Registry.
Of the 99 pairs, half were genetically identical twins, and half were fraternal twins.
The study team assessed the twins' lifetime work and hobby activities, specifically inquiring about occupational tasks
such as electrical work, industrial machinery repair, and dry cleaning, which would potentially expose people to chemicals previously linked
to Parkinson's. The researchers also collected information on head injuries, which are suspected to increase Parkinson’s risk, and smoking
history, which is reported to decrease Parkinson’s risk.
Expert evaluators, unaware of which study subjects had Parkinson's, reviewed this information and calculated lifelong
exposure to six chemicals: TCE, PERC, carbon tetrachloride, n-hexane, xylene and toluene. Of these, TCE and PERC posed a notable risk for
developing Parkinson's.
"The potential importance is great, since both solvents persist in the environment and are commonly used," said Dr.
Goldman,
"Parkinson's was sixfold more common in twins exposed to TCE, and ninefold more common in twins exposed to TCE or PERC."
There was also a trend toward a tenfold increase in Parkinson’s disease in twins exposed to PERC alone.
In this study researchers looked only at occupational chemical exposure, and the association with job categories tended
toward significance only for the industrial machinery repairer and industrial worker categories.
However, the chemicals evaluated here are found outside industrial settings as well. PERC is the leading chemical used in
garment dry cleaning. TCE is the most frequently reported organic groundwater contaminant, was once used as general anesthetic and coffee
decaffeinating agent, and is still used widely as a metal degreasing agent.
TCE has also been linked to Parkinson's by other research groups. Researchers at the University of Kentucky, Lexington,
and the Kangwon National University in South Korea have reported an association between TCE and Parkinson’s in highly-exposed industrial
workers, and have also demonstrated that TCE causes neurodegeneration in animal models.
The analysis described in this report expands on preliminary findings presented at the 2010 American Academy of Neurology
meeting. The new paper quantifies the individuals' exposures to the chemicals in terms of successive years and cumulative exposure over their
lifetime.
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About Parkinson’s Disease
Parkinson's disease is a disorder
that affects nerve cells, or neurons, in a part of the brain that controls muscle movement. In Parkinson's, neurons that make a
chemical called dopamine die or do not work properly. Dopamine normally sends signals that help coordinate your movements. No one
knows what damages these cells. Symptoms of Parkinson's disease may include
● Trembling of hands, arms,
legs, jaw and face
● Stiffness of the arms, legs
and trunk
● Slowness of movement
● Poor balance and
coordination
As symptoms get worse, people
with the disease may have trouble walking, talking or doing simple tasks. They may also have problems such as depression, sleep
problems or trouble chewing, swallowing or speaking.
Parkinson's usually begins around
age 60, but it can start earlier.
It is more common in men than in
women. There is no cure for Parkinson's disease. A variety of medicines sometimes help symptoms dramatically.
>>
Parkinson's Disease
(National Institute of Neurological Disorders and Stroke)
>>
Parkinson's Disease-Interactive Turotial
(Patient Education Institute) |
Dr. Tanner notes that while the association between chemical exposure and Parkinson's is strong, one limitation of the
research is the small number of individuals studied. "It will be important to replicate these results in additional populations with
well-characterized exposure histories,” she commented.
Wendy Galpern, M.D., Ph.D., program director at NINDS, agreed that replication of these results is necessary. "This
epidemiologic study is a noteworthy addition to our growing understanding of the association between environmental exposures and Parkinson's
disease," Dr. Galpern said.
"The identification of specific chemicals linked to this neurodegenerative disorder may have implications for disease
prevention and an improved understanding of how Parkinson's develops."
The research was supported by NINDS/NIH, The Michael J. Fox Foundation for Parkinson's Research, New York, Parkinson's
Unity Walk, Kingston, N.J., The Valley Foundation, Los Gatos, Calif., and James and Sharron Clark.
For more information about Parkinson's Disease, visit the Parkinson's Disease fact sheet on the NINDS website:
www.ninds.nih.gov/PD
NINDS is the nation's leading funder of research on the brain and nervous system. The NINDS mission is to reduce the burden of
neurological disease — a burden borne by every age group, by every segment of society, by people all over the world.
About the National Institutes of Health (NIH):
NIH, the nation's medical research agency, includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting
basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases.
For more information about NIH and its programs, visit
www.nih.gov.
Links to Archived News Reports About
Parkinson's Disease
Seniors, Other Parkinson Patients Gain from Deep
Brain Stimulation but Take Serious Risk
Few previous randomized trials comparing treatments,
most excluded senior citizens - watch video - Jan. 7, 2009
Physical Activity Slows the Progress of Parkinson’s
in Study
U. of Michigan programs promote strengthening and
conditioning of patients
Aug. 11, 2008
Parkinson's Community Steps Out to Find a Cure at
the 14th Annual Parkinson's Unity Walk
Second most common chronic neurological disorder in
senior citizens after Alzheimer's
April 23, 2008
Parkinson’s Patients Play Nintendo to Test Occupational Therapy
Foul ball and improved walking ability brings a cheer
for Ingrid Bell
April 7, 2008
Researchers Claim Omega-3 Fatty Acids Protect Brain
from Parkinson's
Protection may come from DHA omega-3 eating up
dangerous omega-6 fatty acid in brain
Nov. 26, 2007
PET Scans Show
Gene Therapy Normalizes Brain Function in Parkinson’s
Study focuses on power of modern brain scans
to show that gene therapy altered brain activity in a favorable
way
Nov. 20, 2007
It's How Amyloid Fiber is Built that May Set Stage
for Alzheimer's, Parkinson's
Study of bacteria’s role in forming fibers leads to
new theory
July 13, 2007
Exelon Patch is First Approved by FDA to Treat
Alzheimer’s Disease
Patch also approved to treat Parkinson's disease
dementia
July 9, 2007
New Treatment in Battle Against Parkinson’s May Come
from Discovery
New protein appears to protect and rescue damaged
dopamine neurons
July 5, 2007
Parkinson’s Disease Risks Lower with High Levels of
Urate in Blood
Large Harvard study finds potent antioxidant works
against oxidative stress
June 22, 2007
Parkinson’s Disease Treatment with Gene Therapy
Shows Promise
First such clinical trial may lead to effective
management of disease that hits mostly senior citizens
June 22, 2007
Engineers Say They Now Know How Brain Pacemakers
Help Parkinson’s Patients
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at Molecular Level
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Researchers find 'Probable Cause' for Parkinson's,
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