Parkinson’s Disease, Pesticides and a Sense of Smell – Two New Studies

Parkinson’s disease (PD) and its uncontrollable tremors has long been suspected to have both a genetic and environmental cause. 

For the first time in this study, from Duke University Medical Center and the University of Miami Miller School of Medicine,  researchers have found those exposed to pesticides and insecticides had a 1.6 times higher risk of developing Parkinson’s when compared to their relatives with low exposure.

Researchers interviewed 319 Parkinson’s patients and their relatives, who presumably had a similar genetic makeup, about their level of exposure to herbicides and insecticides such as organochlorides and organophosphates.

The study finds that overall, people with PD were more likely to report direct pesticide application than their relatives who did not have PD.

"Previous studies have shown that individuals with Parkinson's disease are over twice as likely to report being exposed to pesticides as unaffected individuals, but few studies have looked at this association in people from the same family or have assessed associations between specific classes of pesticides and Parkinson's disease," study author Dana Hancock said in a prepared statement. 

Parkinson’s disease affects about 1 million people in the U.S.. While a rare genetic defect is believed to account for a small proportion of those with the disease, that leaves unanswered the question as to what causes the majority of cases of Parkinson’s.

Pesticide exposure has long been associated with neurological impairment and reduced male fertility.

The study is published in the open-access journal BMC Neurology.

In another study released today in the Annals of Neurology,  2,267 men were given olfactory tests in the 1990s. That is a test for the ability to identify and distinguish smells. The men were followed for eight years.  35 of the men developed Parkinson’s disease.

In those men, the inability to identify odors preceded the development of Parkinson’s by at least four years. 

Even after eliminating other complicating factors such as smoking, aging and less cognitive function, those who could not smell as well had a five times greater risk of developing Parkinson’s –indicating that may be  an early sign that one is on the road to developing Parksinson’s two to seven years down the road.

Why?   It could be that abnormal clumps of proteins, which are a marker for the disease, form in the olfactory areas of Parkinson’s patients.  That confirms earlier research that found from brain dissection of Parkinson’s patients showing their olfactory brain regions were most affected by degeneration. 

An impaired sense of smell could be an early sign of Parkinson’s disease as is constipation, sleep disturbances, aging, smoking, more coffee consumption, a reduced cognitive function and excessive daytime sleepiness.

The authors conclude that smell tests could be identify individuals who might want to enroll in drug trials looking for medication to stop or slow progress of the disease.

At present there is no cure for PD but several drug provide relief from its symptoms and deep brain stimulation (DBS)  from a surgically implanted ”pacemaker” in the brain, is providing some people with significant relief.

And last week researchers at Sloan Kettering Institute reported progress in using cloned mice cells to repair the damage in brain cells. #