How do we know if a medical treatment works? The best studies randomly split people into two or more groups. People in one group get the treatment being tested, and the others get comparison treatments. Often the comparison is an inactive placebo pill, although it could be another drug, or even something else completely, like an exercise regime or education program.
An alternative type of medical trial is the observational study. If you're interested in ibuprofen, for example, you could ask people how often they've been taking it each week for the past few years. You then compare people who took it regularly with people who didn't. That's what researchers did in a new study, and they came to the conclusion that ibuprofen is linked to a lower risk of developing Parkinson's disease.
So, does the study mean that ibuprofen is worth taking to ward off Parkinson's? At this stage, the answer is: probably not.
Apart from potential problems with bias, the effect was fairly small. People taking ibuprofen had a risk of Parkinson's that was around 40 percent lower. While this sounds like a lot, the amount of difference it makes would depend on your overall risk of developing Parkinson's. During the study, around 21 in 10,000 people developed Parkinson's. A 40 percent drop would reduce that to 13 in 10,000. That's a difference of just 8 in 10,000--a pretty small difference in risk for any one individual.
Second, ibuprofen has side effects. It irritates the stomach lining, which can lead to stomach ulcers and bleeding in the stomach. Higher doses taken for a long time slightly increase the risk of a heart attack or stroke.
Given uncertainty about the findings, and the side effects of long-term ibuprofen use, it's too soon for doctors to recommend ibuprofen as a way of preventing Parkinson's.
A good point of comparison is the research done on hormone replacement therapy (HRT) for menopause. Observational studies originally suggested HRT helped to prevent heart problems, but high-quality randomized trials eventually found that HRT actually increased the risk of heart disease or a stroke.
What you need to know. It's possible that ibuprofen could reduce the risk of Parkinson's disease, perhaps by reducing inflammation in the brain. But we need more research to know for sure, and the side effects of ibuprofen might outweigh any benefits.
--Philip Wilson, patient editor, BMJ Group
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