The top 10 health stories of 2009, Part 2

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Top 10 health stories, Part 2

Part of the challenge for health-conscious individuals is to determine which health news items are based on strong research and worth taking to heart, and which are not. The editors of the Harvard Health Letter, in consultation with the doctors on its editorial board, offer their choices for the top 10 health stories of each year. Last week's issue of HEALTHbeat covered the editors' first five selections. Here are the stories that made numbers 6 through 10 on the list.

6. These micros are major

Messenger RNA reads the DNA of our genes and uses that code to assemble proteins, the building blocks of all forms of life. In the mid-1990s, researchers discovered small bits of RNA, now known as microRNA, that attach to the messenger version and switch it off, so the protein doesn't get made.

Already microRNAs are playing an important role in helping cancer doctors make more accurate diagnoses and prognoses and choose more effective treatments. Promising results for macular degeneration and respiratory syncytial virus infection have been reported in humans, and successful treatments using microRNAs have been achieved in mice.

Compared to drugs, microRNAs are easy and cheap to manufacture. For cancer, they would mean treatment targeted at the root cause of the disease: mutated genes promulgating wayward proteins. And researchers have high hopes that microRNA medicine will yield pinpoint control, so only diseased cells would be affected. But there's also reason to mix in some caution with the optimism. MicroRNA research is, after all, in the beginning stages and has a good ways to go before maturing into full clinical reality.

7. Blood sugar levels: Seeking the sweet spot

High blood sugar levels aren't just a problem for people with diabetes. Elevated blood sugar is associated with worse outcomes for heart attack and stroke patients and, in fact, for hospital patients of all kinds. Tight blood sugar control, accomplished with intravenous infusions of insulin, are a priority in ICUs throughout the country.

Now it's looking like those guidelines may need to be revised again. Results from a large randomized trial showed that the death rate for tightly controlled patients was higher than it was for patients controlled to more conventional levels.

Overdoing blood sugar control in the ICU might be harmful for several reasons. Low targets result in more episodes of extremely low blood sugar, or hypoglycemia, which can trigger a cascade of events with mortal consequences. The insulin used to achieve low blood sugar may have negative effects. Blood sugar control doesn't make the sugar disappear; it goes into cells. That surge of sugar may disrupt normal cell functions that wind up affecting the heart and other vital organs.

Doctors aren't going to completely abandon controlling the blood sugar of ICU patients. But to paraphrase one commentator on the trial results, they'll now be looking for the "sweet spot" between control that is too tight and too loose.

8. CRP: Ready to make an entrance?

Late in 2008, results from the industry-funded JUPITER trial showed that people with normal LDL cholesterol (or "good" cholesterol) levels (less than 130 mg/dL) but relatively high CRP levels (2 mg/L or higher) could cut their risk of having a heart attack or stroke in half by taking a high dose (20 mg) of a powerful statin drug, rosuvastatin (Crestor). CRP stands for C-reactive protein, a chemical in the blood that's a good indicator of inflammation. Statin drugs are taken primarily to lower LDL levels, but this was added proof that they also calm inflammation.

That first round of JUPITER results made a big splash, but it left room for debate about how CRP testing and lowering should fit into cardiovascular care. People in the trial who reached a very low LDL level (less than 70 mg/dL) cut their risk of having a cardiovascular "event" (heart attack, stroke, and so on) by 55%. But those who achieved a sub-70 LDL and a CRP of less than 2 mg/L lowered their risk by 65%. And reaching a CRP of less than 1 mg/L lowered it by 79%.

Many unanswered questions remain. What are the long-term consequences of taking high doses of potent statins like rosuvastatin? Might changes in diet, or increased physical activity, achieve the same thing?

Still, the JUPITER results add to the evidence showing that cardiovascular disease is fundamentally an inflammatory process. The official LDL-centric guidelines haven't changed, but many doctors are going ahead and ordering CRP tests for their patients with cardiac risk factors, even if their LDL levels are normal.

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9. Weighing the effectiveness of screening tests

Fresh doubts emerged this year about the screening tests for breast and prostate cancers. A provocative analysis in The Journal of the American Medical Association (JAMA) came to the conclusion that the past 20 years of screening mammography for breast cancer and prostate-specific antigen (PSA) testing for prostate cancer have led to detection and treatment of many cancers that pose minimal risk, while achieving only modest reductions in the number of more advanced cases.

The U.S. Preventive Services Task Force came out with new mammography guidelines that said most women should not start getting mammograms before age 50 (the old guidelines said 40) and that it's best for the tests to be done every two years, instead of every year. A huge controversy ensued, which shows, if nothing else, that screening mammography is far from a settled issue.

10. Do your friends make you fat?

A new wave of research is showing that weight gain and a variety of other health-related behaviors have a social dimension, spreading through social networks as if they were contagious. Social networks are the vast webs of relationships we find ourselves in: friends and relatives; their friends and relatives; the friends and relatives of those friends and relatives, and so on.

Network analysis has roots in sociology, anthropology, mathematics, and several other disciplines. Dr. Nicholas Christakis, a Harvard Medical School professor, and James Fowler, a University of California political scientist, have applied the techniques from those fields to health-related issues. They started by painstakingly mapping out a social network based on information supplied by participants in the famous Framingham Heart Study.

Their work has piqued people's interest partly because of some unexpected twists. For example, their obesity study found that your friend's obese friend may increase your chances of becoming obese, even if your friend is not heavy.

How behavior could follow infectious patterns is uncertain, although Christakis and Fowler say subtle social messages of acceptance may get passed along from one person to another. Some say social network researchers are leveraging interesting correlations into causation. A related criticism is that network research has dressed up the time-honored observation that in social matters, like attracts like: clusters of behavior form because we are favorably disposed toward people who behave like we do. Regardless, viewing health-related behavior as a collective phenomenon is fascinating and opens up new avenues for research and experiments in intervention.