Addicted smokers, drinkers less likely to get Parkinson's, study finds
People who are addicted to cigarettes, alcohol or coffee may have a significantly lower risk of developing Parkinson's disease, according to new research.
Doctors in the Netherlands have discovered that a higher consumption of addictive substances can reduce by up to 50% the likelihood of developing the disease, which typically causes tremors and rigidity in older people.
The findings will be presented at the American Academy of Neurology's annual meeting in San Diego today.
Drinking even one cup of coffee per day reduces the chance of getting Parkinson's by 10%, said Dr. Patricia Willems-Giesbergen, lead author of the study. Increasing the number of daily cups of coffee further reduces the risk, she said.
Smoking can decrease the likelihood of getting the crippling disease by 50%, the researchers found.
Doctors had previously made a link between smoking and Parkinson's, but did not know what ingredient, if any, was responsible. They now believe the key may be the release of a chemical in the brain, known as dopamine, which is triggered by addiction to smoking or other substances.
"We knew from previous work that smokers have a lower risk of Parkinson's disease, but we never knew what the reason was -- whether smoking itself protects [people] from getting Parkinson's disease or whether something else is going on that [means] people with Parkinson's disease just don't smoke," she said.
The study says people with addictions or "novelty-seeking" behaviour (for example, people who go on drinking binges) have high dopamine levels. The moment healthy people smoke or drink, neurons in their brain release a surge of dopamine, giving them a rewarding feeling that compels them to repeat the action.
Animals release dopamine every time something novel or new is placed before them -- such as food or a mate. Preliminary evidence suggests pathological gamblers experience dopamine rushes.
People who have Parkinson's, however, usually do not experience the same rewarding sensation when they take addictive agents. The progressive neurological disorder degenerates dopamine-containing cells in their brains.
"We don't think the agent itself protects them, but that there is something else going on in the brains of people with Parkinson's disease that prevents them from getting addicted to [substances]," said Dr. Willems-Giesbergen who works at the Erasmus Medical Center in Rotterdam.
Dopamine, a chemical messenger, is similar to adrenaline. It affects brain processes that control movement, emotional response and ability to experience pleasure and pain.
Dr. Willems-Giesbergen's 10-year study was based on research on 8,000 people, aged 55 and older, living in the suburbs of Rotterdam.
The research throws the widespread notion that nicotine or another ingredient in cigarettes is the key into doubt because of the disease's relationship with other addictive agents.
The study will continue indefinitely as long as the subjects are willing to take part, she said.
Up to 100,000 Canadians are affected by the disease.