A new US study on families with a higher than usual prevalence of Parkinson’s suggests that members who develop the disease are less likely to smoke and drink large amounts of coffee than those who do not.

The research is reported in the Archives of Neurology and was conducted by a team of scientists from the Center for Human Genetics, Duke University Medical Center, Durham, North Carolina.

Parkinson’s disease is a chronic, progressive disorder that results in speech impairment, muscle rigidity, tremors, and slowing of physical movement. The disease is degenerative and caused by a lack of dopamine in the brain. It affects about 1 in 100 people over the age of 65.

The researchers wanted to assess the link between Parkinson’s Disease (PD) and smoking, caffeine (in coffee, tea and soft drinks), and nonsteroidal anti-inflammatory drugs (NSAIDs, for instance aspirin and ibuprofen).

They examined 356 people with PD (average age 66.1 years) and 317 family members without PD (average age 63.7 years) who self-reported on a range of environmental exposures such as current and past dosage, frequency and duration of smoking, and consumption of coffee, caffeine, and NSAIDs.

The patients were based at an academic medical center clinic and were either self-referred or referred by their doctor. Over half of the group with PD were male, while over half of the the group without PD were female. The results were controlled for age and sex.

The findings showed:

— Patients with PD were 40 per cent less likely to say they had ever smoked compared to relatives without PD.
— A significant inverse association between smoking and PD.
— More coffee drinking was inversely associated with PD, measured on both dosage and intensity.
— No significant associations between NSAIDs and PD.

The researchers concluded that “Inverse associations of smoking and caffeine were corroborated using families with PD, thus emphasizing smoking and caffeine as important covariates to consider in genetic studies of PD”.

Speculating about what the results might mean, the researchers were uncertain about how smoking and caffeine affects the brain in relation to PD.

This research does not prove that smoking and caffeine prevents PD, only that people with PD in their families who did not get PD were less likely to be non -smokers and low caffeine consumers.

Parkinson’s disease is mostly idiopathic, of unknown origin, and a small proportion of cases are likely to have genetic cause.

The researchers say that this research simply means that when looking at the genetics of PD, it is also important to consider environmental factors, such as smoking and caffeine exposure, because there seems to be a strong connection.

It could be that people with low levels of dopamine, who go on to develop PD, are for some reason also less likely to smoke and drink large amounts of caffeine.

“Smoking, Caffeine, and Nonsteroidal Anti-inflammatory Drugs in Families With Parkinson Disease.”
Dana B. Hancock; Eden R. Martin; Jeffrey M. Stajich; Rita Jewett; Mark A. Stacy; Burton L. Scott; Jeffery M. Vance; William K. Scott.
Arch Neurol. 2007;64:576-580.

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Click here for Parkinson’s Disease Society (UK).

Written by: Catharine Paddock
Writer: Medical News Today