Study finds that the pesticides rotenone and paraquat are associated with Parkinson’s disease


National Institutes of Health research shows a link between use of two pesticides, rotenone and paraquat, and Parkinson’s disease. People who used either pesticide developed Parkinson’s disease approximately 2.5 times more often than non-users.

The study was a collaborative effort conducted by researchers at the National Institute of Environmental Health Sciences (NIEHS), which is part of the National Institutes of Health, and the Parkinson’s Institute and Clinical Center in Sunnyvale, Calif.

“Rotenone directly inhibits the function of the mitochondria, the structure responsible for making energy in the cell,” said Freya Kamel, Ph.D., a researcher in the intramural program at NIEHS and co-author of the paper appearing online in the journal Environmental Health Perspectives. “Paraquat increases production of certain oxygen derivatives that may harm cellular structures. People who used these pesticides or others with a similar mechanism of action were more likely to develop Parkinson’s disease.

The authors studied 110 people with Parkinson’s disease and 358 matched controls from the Farming and Movement Evaluation (FAME) Study (http://www.niehs.nih.gov/research/atniehs/labs/epi/studies/fame/index.cfm) to investigate the relationship between Parkinson’s disease and exposure to pesticides or other agents that are toxic to nervous tissue. FAME is a case-control study that is part of the larger Agricultural Health Study (http://www.niehs.nih.gov/research/atniehs/labs/epi/studies/ahs/index.cfm), a study of farming and health in approximately 90,000 licensed pesticide applicators and their spouses. The investigators diagnosed Parkinson’s disease by agreement of movement disorder specialists and assessed the lifelong use of pesticides using detailed interviews.

There are no home garden or residential uses for either paraquat or rotenone currently registered. Paraquat use has long been restricted to certified applicators, largely due to concerns based on studies of animal models of Parkinson’s disease. Use of rotenone as a pesticide to kill invasive fish species is currently the only allowable use of this pesticide.

“These findings help us to understand the biologic changes underlying Parkinson’s disease. This may have important implications for the treatment and ultimately the prevention of Parkinson’s disease,” said Caroline Tanner, M.D., Ph.D., clinical research director of the Parkinson’s Institute and Clinical Center, and lead author of the article.

The NIEHS supports research to understand the effects of the environment on human health and is part of NIH. For more information on environmental health topics, visit www.niehs.nih.gov. Subscribe to one or more of the NIEHS news lists (www.niehs.nih.gov/news/releases/newslist/index.cfm) to stay current on NIEHS news, press releases, grant opportunities, training, events, and publications.

The National Institutes of Health (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. It is the primary federal agency for conducting and supporting basic, clinical and translational medical research, and it investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.


Reference: Tanner CM, Kamel F, Ross GW, Hoppin JA, Goldman SM, Korell M, Marras C, Bhudhikanok GS, Kasten M, Chade AR, Comyns K, Richards MB, Meng C, Priestly B, Fernandez HH, Cambi F, Umbach DM, Blair A, Sandler DP, Langston JW. 2011. Rotenone, paraquat and Parkinson’s disease. Environ Health Perspect; doi:10.1289/ehp.1002839 [Online 26 January 2011].

What is Parkinson’s Disease?

Source: the National Institute of Neurological Disorders and Stroke – NINDS

Parkinson’s disease (PD) belongs to a group of conditions called motor system disorders, which are the result of the loss of dopamine-producing brain cells. The four primary symptoms of PD are tremor, or trembling in hands, arms, legs, jaw, and face; rigidity, or stiffness of the limbs and trunk; bradykinesia, or slowness of movement; and postural instability, or impaired balance and coordination. As these symptoms become more pronounced, patients may have difficulty walking, talking, or completing other simple tasks. PD usually affects people over the age of 50.  Early symptoms of PD are subtle and occur gradually.  In some people the disease progresses more quickly than in others.  As the disease progresses, the shaking, or tremor, which affects the majority of PD patients may begin to interfere with daily activities.  Other symptoms may include depression and other emotional changes; difficulty in swallowing, chewing, and speaking; urinary problems or constipation; skin problems; and sleep disruptions.  There are currently no blood or laboratory tests that have been proven to help in diagnosing sporadic PD.  Therefore the diagnosis is based on medical history and a neurological examination.  The disease can be difficult to diagnose accurately.   Doctors may sometimes request brain scans or laboratory tests in order to rule out other diseases.

 

Is there any treatment?

At present, there is no cure for PD, but a variety of medications provide dramatic relief from the symptoms.  Usually, patients are given levodopa combined with carbidopa.  Carbidopa delays the conversion of levodopa into dopamine until it reaches the brain.  Nerve cells can use levodopa to make dopamine and replenish the brain’s dwindling supply.  Although levodopa helps at least three-quarters of parkinsonian cases, not all symptoms respond equally to the drug. Bradykinesia and rigidity respond best, while tremor may be only marginally reduced. Problems with balance and other symptoms may not be alleviated at all.  Anticholinergics may help control tremor and rigidity.  Other drugs, such as bromocriptine, pramipexole, and ropinirole, mimic the role of dopamine in the brain, causing the neurons to react as they would to dopamine.  An antiviral drug, amantadine, also appears to reduce symptoms.  In May 2006, the FDA approved rasagiline to be used along with levodopa for patients with advanced PD or as a single-drug treatment for early PD. 

In some cases, surgery may be appropriate if the disease doesn’t respond to drugs. A therapy called deep brain stimulation (DBS) has now been approved by the U.S. Food and Drug Administration. In DBS, electrodes are implanted into the brain and connected to a small electrical device called a pulse generator that can be externally programmed. DBS can reduce the need for levodopa and related drugs, which in turn decreases the involuntary movements called dyskinesias that are a common side effect of levodopa. It also helps to alleviate fluctuations of symptoms and to reduce tremors, slowness of movements, and gait problems. DBS requires careful programming of the stimulator device in order to work correctly.

For more information about Parkinson’s Disease