Sloppy Headlines on Parkinson's Disease

Here's a catchy headline that's guaranteed to get your attention: "Smoking and Caffeine May Protect Against Parkinson's Disease."

It was written by the good folks at the Duke University press office. But it does a disservice to anyone who has Parkinson's disease, or cares for or loves someone with the neuro-degenerative condition.

To make matters worse, it gave journalists permission to use similarly dumb headlines for their copy, like this one from the Miami Herald: "Study: Cigarettes, coffee may help ward off Parkinson's."

How sloppy is the Duke press release on Parkinson's disease? Let me count the ways:

1. Regular readers of The Health Media Watch should pick up right away on the "Mighty May" in this title. Whenever you read the word "may" in a health article (or press release) you should always add the phrase "or may not" to the sentence. In other words, "Smoking and Caffeine May or May Not Protect Against Parkinson's Disease."

2. The risk picture is incomplete. "Individuals with Parkinson's disease were half as likely to report ever smoking and a third as likely to report current smoking compared with unaffected relatives," according to the press release. No clue what the absolute risk is of developing Parkinson's disease in one's lifetime as to compared to, oh let's say, LUNG CANCER.

Instead we get just the following dutiful sentence: "Smoking cigarettes and consuming copious amounts of caffeine carry their own risks and should not be taken up in an attempt to avoid developing Parkinson's disease, cautions study investigator Burton L. Scott, M.D., Ph.D., associate professor of medicine."

For the record, about 1 in 100 (or 1%) of people develop Parkinson's disease at some point in their LIFETIME, according to data from the Centers for Disease Control.

But a 68 year-old man who has smoked two packs per day for 50 years and continues to smoke has a 15% chance of developing lung cancer in just the NEXT TEN YEARS (Bach PB, et al. Journal of the National Cancer Institute, 2003).

3. An association does not prove causation. Maybe the folks with Parkinson's were less likely to have smoked because they have less addictive personalities. In that case, smoking would be a side effect of whatever genetic predisposition made you less likely to develop Parkinson's disease. Or maybe, as Maggie Fox of Reuters pointed out in her article, people who are predisposed to developing Parkinson's disease just don't like coffee as much as their counterparts.

Vitamins Reduce Cancer Risk--Relatively Speaking

A new study shows that women who take multivitamins and folic acid during pregnancy reduce the chance that their baby will develop some childhood cancers by almost 50%. Your first question on reading this should be "50% of what?"

In other words, you want to know what the absolute risk of developing pediatric cancer is. Then you can figure out whether a 50% reduction (the so-called relative risk) is a lot or a little.

Fortunately, the overall risk of childhood cancer--such as leukemia or neuroblastoma--is very low. Joseph Hall of the Toronto Star, for example, characterizes the absolute risk of neuroblastoma this way: "the disease affects about one in every 6,500 children under five years in North America."

Do the math and you realize that he's talking about a 0.015% chance of developing neuroblastoma. A 50% reduction in relative risk means that the real-world chance of developing a neuroblastoma has dropped from 0.015% to less than 0.008%.

Such a slight decrease is not a bad thing--especially when you consider how easy it is to take vitamin supplements during pregnancy and how devastating neuroblastoma can be. But most health stories in the popular media focus on relative risk and ignore absolute risk, giving you an incomplete picture.

Women and Heart Disease

You've got to understand risk if you want to stay healthy. Why do women fear breast cancer more than heart disease? As a group, women have a 4% chance of dying from breast cancer vs. a 38% chance of dying from heart disease. But because women are less likely than men to develop heart disease in their 40s, they (and their doctors) often assume they don't need to worry too much about cardiac problems.

So, the American Heart Association has come up with new guidelines on preventing heart disease that emphasize a woman's lifetime risk. The idea is for women to understand their real risks better and, hopefully, to motivate them to exercise more and adopt a healthier diet. Indeed, there's probably more you can do to prevent heart disease than to prevent breast cancer anyway.